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Trees allocate C from sources to sinks by way of a series of processes involving carbohydrate transport and utilization. Yet these dynamics are not well characterized in trees, and it is unclear how these dynamics will respond to a warmer world. Here, we conducted a warming and pulse-chase experiment on Eucalyptus parramattensis growing in a whole-tree chamber system to test whether warming impacts carbon allocation by increasing the speed of carbohydrate dynamics. We pulse-labelled large (6-m tall) trees with 13 C-CO2 to follow recently fixed C through different organs by using compound-specific isotope analysis of sugars. We then compared concentrations and mean residence times of individual sugars between ambient and warmed (+3°C) treatments. Trees dynamically allocated 13 C-labelled sugars throughout the aboveground-belowground continuum. We did not, however, find a significant treatment effect on C dynamics, as sugar concentrations and mean residence times were not altered by warming. From the canopy to the root system, 13 C enrichment of sugars decreased, and mean residence times increased, reflecting dilution and mixing of recent photoassimilates with older reserves along the transport pathway. Our results suggest that a locally endemic eucalypt was seemingly able to adjust its physiology to warming representative of future temperature predictions for Australia.

Autotrophic respiration is a major driver of the global C cycle and may contribute a positive climate warming feedback through increased atmospheric concentrations of CO2 . The extent of this feedback depends on plants' ability to acclimate respiration to maintain a constant carbon use efficiency (CUE). We quantified respiratory partitioning of gross primary production (GPP) and CUE of field-grown trees in a long-term warming experiment (+3°C). We delivered a 13 C-CO2 pulse to whole tree crowns and chased that pulse in the respiration of leaves, whole crowns, roots, and soil. We also measured the isotopic composition of soil microbial biomass and the respiration rates of leaves and whole crowns. We documented homeostatic respiratory acclimation of foliar and whole-crown respiration rates; the trees adjusted to experimental warming such that leaf-level respiration rates were not increased. Experimental warming had no detectable impact on respiratory partitioning or mean residence times. Of the 13 C label acquired by the trees, aboveground respiration consumed 10%, belowground respiration consumed 40%, and the remaining 50% was retained. Experimental warming of +3°C did not alter respiratory partitioning at the scale of entire trees, suggesting that complete acclimation of respiration to warming is likely to dampen a positive climate warming feedback.

Atmospheric carbon dioxide enrichment (eCO2) can enhance plant carbon uptake and growth1–5, thereby providing an important negative feedback to climate change by slowing the rate of increase of the atmospheric CO2 concentration6. Although evidence gathered from young aggrading forests has generally indicated a strong CO2 fertilization effect on biomass growth3–5, it is unclear whether mature forests respond to eCO2 in a similar way. In mature trees and forest stands7–10, photosynthetic uptake has been found to increase under eCO2 without any apparent accompanying growth response, leaving the fate of additional carbon fixed under eCO2 unclear4,5,7–11. Here using data from the first ecosystem-scale Free-Air CO2 Enrichment (FACE) experiment in a mature forest, we constructed a comprehensive ecosystem carbon budget to track the fate of carbon as the forest responded to four years of eCO2 exposure. We show that, although the eCO2 treatment of +150 parts per million (+38 per cent) above ambient levels induced a 12 per cent (+247 grams of carbon per square metre per year) increase in carbon uptake through gross primary production, this additional carbon uptake did not lead to increased carbon sequestration at the ecosystem level. Instead, the majority of the extra carbon was emitted back into the atmosphere via several respiratory fluxes, with increased soil respiration alone accounting for half of the total uptake surplus. Our results call into question the predominant thinking that the capacity of forests to act as carbon sinks will be generally enhanced under eCO2, and challenge the efficacy of climate mitigation strategies that rely on ubiquitous CO2 fertilization as a driver of increased carbon sinks in global forests. Carbon dioxide enrichment of a mature forest resulted in the emission of the excess carbon back into the atmosphere via enhanced ecosystem respiration, suggesting that mature forests may be limited in their capacity to mitigate climate change.

Rhizosphere processes are integral to carbon sequestration by terrestrial ecosystems in response to rising concentrations of atmospheric CO2. Yet, the nature and magnitude of rhizosphere responses to elevated CO2, particularly in nutrient and water-limited forest ecosystems, remain poorly understood. We investigated rhizosphere responses (enzyme activities and nutrient availability) to atmospheric CO2 enrichment (ambient +150 μmol CO2 mol−1) in a phosphorus-limited mature eucalypt woodland in south-eastern Australia (the EucFACE experiment). Following 17 months of treatment, the activity of rhizosphere soil exoenzymes related to starch and cellulose degradation decreased between 0 and 10 cm and increased from 10 to 30 cm depth under elevated CO2. This response was concurrent with increases in nitrogen and phosphorus availability and smaller C:P nutrient ratios in rhizosphere soil under elevated CO2. This nutrient-poor eucalypt woodland exhibited rhizosphere responses to atmospheric CO2 enrichment that increased nutrient availability in rhizosphere soil and suggest accelerated rates of soil organic matter decomposition, both of which may, in turn, promote plant growth under elevated CO2 concentrations.

Atmospheric carbon dioxide enrichment (eCO2) can enhance plant carbon uptake and growth1,2,3,4,5, thereby providing an important negative feedback to climate change by slowing the rate of increase of the atmospheric CO2concentration6. While evidence gathered from young aggrading forests has generally indicated a strong CO2fertilization effect on biomass growth3,4,5, it is unclear whether mature forests respond to eCO2in a similar way. In mature trees and forest stands7,8,9,10, photosynthetic uptake has been found to increase under eCO2without any apparent accompanying growth response, leaving an open question about the fate of additional carbon fixed under eCO24, 5, 7,8,9,10,11. Here, using data from the first ecosystem-scale Free-Air CO2Enrichment (FACE) experiment in a mature forest, we constructed a comprehensive ecosystem carbon budget to track the fate of carbon as the forest responds to four years of eCO2exposure. We show that, although the eCO2treatment of ambient +150 ppm (+38%) induced a 12% (+247 gCm-2yr-1) increase in carbon uptake through gross primary production, this additional carbon uptake did not lead to increased carbon sequestration at the ecosystem level. Instead, the majority of the extra carbon was emitted back into the atmosphere via several respiratory fluxes, with increased soil respiration alone contributing ∼50% of the total uptake surplus. Our results call into question the predominant thinking that the capacity of forests to act as carbon sinks will be generally enhanced under eCO2, and challenge the efficacy of climate mitigation strategies that rely on CO2fertilization as a driver of increased carbon sinks in standing forests and afforestation projects.

Experimental evidence from a mature, phosphorous-limited, eucalypt forest finds that aboveground productivity was not significantly stimulated by elevated CO2. Findings suggest that this effect may be limited across much of the tropics. Rising atmospheric CO2 stimulates photosynthesis and productivity of forests, offsetting CO2 emissions1,2. Elevated CO2 experiments in temperate planted forests yielded ∼23% increases in productivity3 over the initial years. Whether similar CO2 stimulation occurs in mature evergreen broadleaved forests on low-phosphorus (P) soils is unknown, largely due to lack of experimental evidence4. This knowledge gap creates major uncertainties in future climate projections5,6 as a large part of the tropics is P-limited. Here, we increased atmospheric CO2 concentration in a mature broadleaved evergreen eucalypt forest for three years, in the first large-scale experiment on a P-limited site. We show that tree growth and other aboveground productivity components did not significantly increase in response to elevated CO2 in three years, despite a sustained 19% increase in leaf photosynthesis. Moreover, tree growth in ambient CO2 was strongly P-limited and increased by ∼35% with added phosphorus. The findings suggest that P availability may potentially constrain CO2-enhanced productivity in P-limited forests; hence, future atmospheric CO2 trajectories may be higher than predicted by some models. As a result, coupled climate–carbon models should incorporate both nitrogen and phosphorus limitations to vegetation productivity7 in estimating future carbon sinks.

Bis(4,4,6-trimethyl-1,3,2-dioxaphosphorinane-2-thione-2-thiolato)cobalt(II) complexes with nitrogen and phosphorus containing Lewis bases of the type, [Co(S2 )*Ln] (where L = pyridine, n = 2; L = 2-picoline, 3-picoline, triphenylphosphine, 2,2′-bipyridine, 1,10-phenanthroline; n = 1) were prepared by the addition of the Lewis base to an aqueous solution of CoCl2 · 6H2O followed by the addition of NH4S2 to yield a greenish-blue solution from which the adduct was extracted by addition of benzene These newly synthesized compounds were characterized by elemental analysis, IR and UV–Vis spectroscopy and magnetic measurements. The results for adducts with pyridine, 2,2′-bipyridine, 1,10-phenanthroline are consistent with distorted octahedral geometry around the central metal atom whereas those with 2-picoline, 3-picoline and triphenylphosphine are consistent with distorted trigonal bipyramidal geometry, as is confirmed by the single crystal X-ray crystal structures of [Co(S2 )2(2-CH3-NC5H4)] and [Co(S2 )2(3-CH3-NC5H4)].

Arsenic(III), antimony(III) and bismuth(III) compounds of the type, [M{S2P(OR)2}3] (where M = As, Sb and Bi; R = o-, m-, p-C6H4Me) were obtained by reactions of MCl3 with ammonium salts of the corresponding O,O′-ditolyl dithiophosphate on refluxing in benzene. These compounds were characterized by elemental analysis, IR, 1H NMR and 31P NMR spectroscopy. The single crystal X-ray structures of three representative compounds were determined. [As{S2P(OC6H4Me-m)2}3]·0.5C6H14 crystallizes as triclinic in the space group P 1 ¯ with a = 10.9396(1), b = 14.1891(2), c = 17.5359(2) A, α = 70.731(1), β = 84.734(1), γ = 74.205(1)°, Z = 4, V = 2472.37(5) A3. [Sb{S2P(OC6H4Me-m)2}3] and [Bi{S2P(OC6H4Me-m)2}3] both crystallize as monoclinic in the space group P21 with a = 12.4520(3), b = 22.8760(5), c = 16.2165(4) A, β = 93.022(1)°, Z = 4, V = 4612.9(2) A3 and with a = 12.4903(2), b = 22.9554(4), c = 16.1032(3) A, β = 92.4300(10)°, Z = 4, V = 4612.96(14) A3, respectively. In all three molecules, the central metal atom is surrounded by all six sulfur atoms of the three chelating anisobidentate O,O′-ditolyl dithiophosphate groups in a pseudo trigonally distorted octahedron with a lone pair positioned on one of the triangular octahedral faces. The three metal sulfur bonds adjacent to the lone pair (capped face) are longer than the three furthest from the lone pair (uncapped face). Inter-ligand angles between the longer bonds are greater than those between the shorter bonds.

Bis(O,O'-ditolyl/dibenzyl dithiophosphato)cobalt(II) complexes with pyridine ligands of the type [Co{S2P(OR)(2)}(2)(C5H5N)(2)] (R = o-, m-, p-C6H4Me, CH2Ph) have been synthesized by the reaction of CoCl2(C5H5N)(2) and the corresponding ammonium salt of O,O'-ditolyl/dibenzyl dithiophosphate in methanol. These newly synthesized adducts were characterized by elemental analysis, IR, UV-Vis spectroscopy, magnetic susceptibility measurements and single crystal X-ray diffraction. These structures confirm that in the pyridine complex the geometry around the cobalt metal centre is distorted octahedral, and in the amine complex it is distorted trigonal bipyramidal. (C) 2008 Elsevier Ltd. All rights reserved.

Bis(O,O-dialkylmonothiophosphato)cobalt(II) complexes of the type [Co{O(S)P(OR)2}2] (where R = Prn, Pri, Bun) were prepared under anhydrous conditions by the reaction of cobalt(II) dichloride hexahydrate with the sodium salts of dialkyl monothiophosphoric acids. The reactions of these blue tetrahedral complexes with nitrogen bases such as pyridine (C5H5N or py) and 2,2-bipyridyl (C10H8N2 or bipy) resulted in the pink/orange octahedral adducts [Co{O(S)P(OPri)2}2(C5H5N)4], [Co{O(S)P(OPrn)2}2(C10H8N2)2] and [Co{O(S)P(OBun)2}2(C10H8N2)2]. These compounds were characterized by elemental analysis, IR spectroscopy, magnetic measurements and the single crystal X-ray diffraction structures of two of the adducts of the monothiophosphate complexes, [Co{O(S)P(OPri)2}2(C5H5N)4] and [Co{O(S)P(OPrn)2}2(C10H8N2)2], which are the first examples of this class of compounds. [Co{O(S)P(OPri)2}2(C5H5N)4] crystallizes as triclinic in the space group P 1 ¯ with the cell parameters a = 9.0515(4) A, b = 10.1629(5) A, c = 11.8468(5) A, α = 88.389(3)°, β = 71.984(4)°, γ = 69.181(3)°, Z = 1, V = 964.57(8) A3 and [Co{O(S)P(OPrn)2}2(C10H8N2)2] crystallizes as monoclinic in the space group C2/c with the cell parameters, a = 8.404(2) A, b = 22.855(5) A, c = 18.913(4) A, β = 97.56(3)°, Z = 4, V = 3601(1) A3. These structures contain a unidentate bonding of the monothiophosphate ligands through oxygen, with the geometry of the CoO2N4 coordination sphere around cobalt being distorted octahedral.

A series of binuclear oxomolybdenum(V) O,O′-ditolyl dithiophosphate complexes, Mo2O3[S2P(OR)2]4 (R = o-, m-, p-C6H4Me) were synthesized by drop wise addition of aqueous solution of the ammonium salt of O,O′-ditolyl dithiophosphoric acid into an acidic solution of sodium molybdate with constant stirring to yield purple solids. Dioxomolybdenum(VI) O,O′-ditolyl dithiophosphate complexes, MoO2[S2P(OR)2]2 (R = o-, m-, p-C6H4Me and CH2C6H5) were also synthesized by reducing Mo2O3[S2P(OR)2]4 with OPPh3 in benzene to yield yellow solids. These complexes were characterized by elemental analysis and IR, 1H and 31P NMR spectroscopy and, in three cases, by X-ray crystallography. In Mo2O3[S2P(OC6H4Me-o)2]4 and Mo2O3[S2P(OC6H4Me-m)2]4, the environment around each molybdenum atom can be described as the expected distorted octahedral, consisting of one terminal and one bridging oxygen along with the four chelating sulfur atoms of the dithio ligands, with one Mo–S distance being significantly longer than the other three. In MoO2[S2P(OC6H4Me-p)2]2 the geometry around the Mo atom is again distorted octahedral with two cis terminal oxygen atoms and two anisobidentate dithiophosphate ligands.

Reactions of Me 2 SiCl 2 in a 1:2 molar ratio with internally functionalized oximes in the presence of Et 3 N in anhydrous benzene afford compounds of the type [Me 2 Si{ON C(R)Ar} 2 ] {where R = Me, Ar = 2-C 5 H 4 N ( 1 ), 2-C 4 H 3 O ( 2 ), 2-C 4 H 3 S ( 3 ); R = H, Ar = 2-C 5 H 4 N ( 4 ), 2-C 4 H 3 O ( 5 ), 2-C 4 H 3 S ( 6 )}. Molecular weight measurements of all these derivatives in freezing benzene and the FAB mass spectral studies of 1 and 6 indicate that these complexes are monomeric. The 1 H and 13 C{ 1 H} NMR spectra suggest that the oximate moieties are monofunctional monodentate in solution. 29 Si{ 1 H} NMR signals appear in the region expected for tetra-coordinated dimethyl silicon atoms. Single crystal X-ray diffraction analysis of [Me 2 Si{ON C(H)C 4 H 3 O-2} 2 ] ( 5 ) confirms the presence of a distorted tetrahedron as the immediate environment around silicon. Secondary weak β-donor bonding is also observed in the solid state, indicating that silicon is in the (4+2) coordination state. The TGA curve of [Me 2 Si{ON C(H)C 4 H 3 O-2} 2 ] shows the high thermal stability and volatile nature of the complex. A comparison of hydrolytic studies of a mixture of [Me 2 Si{ON C(CH 3 )C 4 H 3 O-2} 2 ] and Al(OPr i ) 3 in a 1:2 molar ratio with those of pure Al(OPr i ) 3 under similar conditions by the sol–gel technique suggests the formation of a silicon embedded amorphous powder 7 and γ-alumina 8 , respectively. The variation in specific surface area, total pore volume and pore size indicate formation of mesoporous materials.

Reactions of Ni[S2P(OR)2]2(R = o-, m- and p-C6H4Me) with nitrogen donor ligands, viz. pyridine (C5H5N or py), 2,2?-bipyridyl (C10H8N2 or bipy) and 2,9-dimethyl-1,10-phenanthroline (C14H12N2 or dmphen) were carried out in benzene to yield green paramagnetic solids. These adducts were characterized by UV–visible and IR spectroscopy, magnetic measurements and, in two cases, by X-ray crystallography, to indicate how the number of donor atoms and steric factors affect the Ni–S bonding. The molecular structures of 2,2?-bipyridylbis {O,O?-di(p-tolyl)dithiophosphate}nickel(II), Ni[S2P(OC6H4Me-p)2]2 · C10H8N2 and 2,9-dimethyl-1,10-phenanthrolinebis{O,O?-di(o-tolyl)dithiophosphate}nickel(II), Ni[S2P(OC6H4Me-o)2]2 · C14H12N2 · C6H6 are described. The geometry around nickel in the bipyridyl adduct is distorted octahedral with NiS4N2 coordination, whereas in the 2,9-dimethyl-1,10-phenanthroline adduct it is trigonal bipyramidal with NiS3N2 coordination in which one dithiophosphate moiety is bidentate and the other is monodentate.

New heteroleptic oxovanadium(V) chloro oximato complexes of the type [VO{Cl}3-n{ON=C(CH3)(Ar)}n] (where Ar = C4H3O-2, C4H3S-2, C5H4N-2 and n = 1 or 2) have been synthesized in excellent yields by the reaction of VOCl3 with the sodium salts of corresponding internally functionallized oximes in refluxing anhydrous benzene. The complexes are characterized by elemental analyses and spectroscopic techniques (FT-IR, 1H-, 13C{1H}- and 51V-NMR). FAB mass spectral analysis of one of the derivatives, [VOCl{ON=C(CH3)C4H3S}2] indicates the monomeric nature of the complex. 51V-NMR spectral studies of these complexes suggest tetra-coordination around the vanadium atom in solution. However, the single crystal X-ray diffraction study of a redistribution product [VOCl{ON=C(CH3)(C4H3S-2)}2] · CH3OH obtained on recrystallization of [VOCl2{ON=C(CH3)(C4H3S-2)}] from a methanol-hexane mixture shows the vanadium(V) atom is hepta-coordinated with distorted pentagonal bipyramidal geometry. The oxo-atom occupies the axial position while the weakly coordinated CH3OH group is trans to the V=O atom. The two oximato ligands in the approximate pentagonal plane are bonded to the central vanadium atom in dihapto (η2-N, O) manner with the formation of three-membered rings. The V–Cl bond occupies the fifth position in the approximate plane.

New oxovanadium(V) complexes with internally functionalized oximes of the type VO{OPri}3−n{ON C(CH3)(Ar)}n] (where Ar = C4H3O-2, C4H3S-2 and C5H4N-2 and n = 1–3) have been prepared in quantitative yields by the reaction of VO(OPri)3 with the corresponding oximes in various stoichiometric ratios in refluxing anhydrous benzene. The products have been characterized by elemental analyses and spectroscopic (FT IR, 1H, 13C{1H} and 51V NMR) studies. FAB mass spectral analysis of [VO{OPri}{ON C(CH3)C4H3S}2] indicates the monomeric nature of the complex. 51V NMR values for these complexes suggest the formation of tetra-coordinate species in solution. However, the single crystal X-ray diffraction studies of [VO{ON C(CH3)(C4H3O-2)}3] and [VO{ON C(CH3)(C4H3S-2)}3] · 0.5C6H6 exhibit the presence of vanadium(V) atoms in a unique hepta-coordination state with distorted pentagonal bipyramidal geometry in the solid state. The oxo- atom occupies the axial position while the oximato ligands are bonded in a dihapto (η2-N,O) manner with the formation of three membered rings.

The molecular structure of trans-dibromodioxodimethylformamide molybdenum(VI), MoO2Br2(OCHNMe2)2 has been determined. Crystal data: Triclinic, P-1, a = 12.3005(2), b = 15.8763(4), c = 21.1653(6) A, α = 71.992(1)°, β = 88.966(2)°, γ = 89.999(1)°, V = 3930.1(2) A, Z = 12. Trans-dibromodioxodimethylformamide molybdenum(VI) was obtained by the reaction of sodium molybdate, HBr and dimethylformamide and was characterized by IR, and 1H NMR spectroscopy and elemental analysis.

Organotin(IV) complexes of the type, R2Sn[S2P(OR)2]2 (where R = Me, n-Bu and R = o-, m-, p-C6H4Me) have been obtained by the reaction of Me2SnCl2 or n-Bu2SnCl2 with ammonium salts of the corresponding O,O-ditolyl dithiophosphates on stirring in benzene and have been characterized by elemental analysis and IR, 1H, 13C, 31P and 119Sn NMR spectroscopy. Trends in data are discussed. The crystal structures of Me2Sn[S2P(OC6H4Me-o)2]2 and n-Bu2Sn[S2P(OC6H4Me-o)2]2 are reported. The environment around the tin atom in both molecules may be described as having skew-trapezoid bipyramidal geometry.

A non-Schiff base (Te, N, O) ligand MeOC6 H4TeCH2CH2NHCH(CH3)C6H4–2–OH (LH) having a chiral center and its palladium(II) complex [PdClL]·CH2Cl2 (1) have been synthesized. Both have characteristic 1H and 13C NMR spectra. The single crystal structure of the complex 1 has been determined by X-ray diffraction methods. The monoclinic crystals of 1 (space group P21/n) have a=14.581(5) A, b=13.160(5) A and c=20.249(5) A, β=99.398(5)°. The Te $$\cdots $$ Cl secondary interactions [3.303(2)–3.352(2) A] between two nearly square planar palladium complex molecules results in a bimolecular aggregate having a Pd $$\cdots $$ Pd distance 3.203(1) A. The Pd–Te, Pd–N and Pd–O bond lengths are 2.5005(7)/2.4914(7), 2.060(4)/2.061(4) and 2.054(3)/2.044(3) A, respectively.

Lithium 2-thienyltellurolate, generated from 2-thienyl lithium, reacts at -78 degrees C in THF with chloroethyl ethyl sulfide to give a (Te, S) ligand 1-ethylthio-2-[2-thienyltelluro]ethane (L) as a red oil. The complexes [PdCl2(L)] (1), [PtCl2(L)] (2), [Ag(L)(2)][ClO4] (3) and [CuBr(L)](2) (4) were synthesized. The complex [HgCl2(L)] on crystallization decomposed giving Th2TeCl2 (5) [where Th = 2-thienyl], which was characterized by X-ray diffraction on its single crystals. The ligand L and complexes 1-4 exhibit proton and carbon-13 NMR spectra, which are characteristic. The coordination through Te in 1-4 is indicated by downfield coordination shifts in the position of the TeCH2 signal of L. Complex I was characterized by X-ray diffraction on its single crystals. The geometry around Pd is square planar. The Pd-Te, Pd-S and Pd-Cl bond lengths are 2.5040(4), 2.273(1) and 2.322(1)/2.380(1) angstrom, respectively. There are intermolecular interactions between Te (coordinated to Pd) and Cl, and sulfur and Cl. The Te-Cl and S-Cl distances, 3.401 and 3.488 A, respectively, are shorter than the sum of the van der Waal's radii (3.81 and 3.55 A, respectively). The Pd-Pd distance between the two molecules is 3.4156(6) A, greater than the sum of van der Waal's radii (3.26 A). The structure of 5 is typical of that of a tellurium(IV) compound (saw-horse type). The two Te-Cl bond lengths are identical, 2.480(1) A. The geometry around Te in 5 can be best described as pseudo tetrahedral (trigonal bipyramidal with a lone pair on one corner of the triangle).

Reactions of dibromodioxobis(dimethylsulfoxide)molybdenum(VI) with sodium/potassium salts of N,N'-dialkyl dithiocarbamates or O-alkyl dithiocarbonates in 1:1 molar ratio in dichloromethane yield bromodioxomolybdenum(VI) complexes of the type, MoO2Br(S2CNR2)(OSMe2) (R = Et, Pr-n, Pr-i) or MoO2Br(S2COR)(OSMe2) (R = Et, Pr-n, Pr-i). These newly synthesized complexes were characterized by elemental analysis and IR, UV-Vis and H-1 NMR spectroscopy. Crystals of MoO2,Br-2(OSMe2)(2) and MoO2Br(2)(C12H8N2) • CH2Cl2 both have distorted octahedral environments around molybdenum with two cis-oxygen atoms and two trans-bromine atoms along with two cis-dimethylsulfoxide moieties in the former and 1,10-phenanthroline in the latter.

The (P, S) ligand 1-(ethylthio)-2-(diphenylphosphino) ethane (L) is synthesized by reacting Ph2PLi with CH3CH2SCH2CH2Cl. The yield is good (similar to 85%) and the method of preparation is simpler than the liquid ammonia based one reported earlier. Its complexation with Cu(I), Hg(II) and organometallic species of Ru(II) are explored. All the complexes and the ligand exhibit characteristic proton, carbon-13 and phosphorus-31 NMR spectra. The single crystal structure of the Hg(II) complex has been determined. It is found to be a three coordinate complex. The sum of the bond angles at Hg, viz. P(1)-Hg(1)-Br(1), P(1)-Hg(1)-Br(2) and Br(1)-Hg(1)-Br(2), is approximate to 360 degrees. Thus the geometry around Hg can best be described as essentially trigonal planar. The Hg(1)-P(1) bond length is 2.415(1) angstrom and the Hg-Br bond lengths are 2.5152(6) and 2.5952(6) angstrom. There exists a weak secondary interaction between Hg and the S donor site of the ligand [Hg(1)•••S(1) bond distance 3.063(1) A < sum of van der Waal's radii 3.35 A].

The X-ray structure of the triethyl ammonium salt of O,O′-bis(o-tolyl)dithiophosphate, [Et3NH]+[(2-MeC6H4O)2PS2]−, has been determined. Crystal data: Monoclinic, P21/c, a = 15.4342(6) A, b = 10.1913(4) A, c = 14.0729(6) A, β = 100.855(1)∘, V = 2174.0(2) A−3, Z = 4. The immediate environment around phosphorous is distorted tetrahedral with two sulfur and two oxygen atoms in the coordination sphere, with N–H–S bonding involving only one of the sulfur atoms.

Reactions of Sr(II) and Ba(II) chlorides with 2-hydroxybenzophenone and salicylaldehyde, hydroxyaromatic ketones or β-diketones in 1:1:1 molar ratios have resulted in the formation of mixed ligand complexes of the type [MLL′(H2O)2] (M = Sr(II) or Ba(II); HL = 2-hydroxybenzophenone and HL′ = salicylaldehyde, 2-hydroxyacetophenone, 2-hydroxypropiophenone, pentane-2,4-dione, 1-phenylbutane-1,3-dione or 1,3-diphenylpropane-1,3-dione). These complexes have been characterized by elemental analyses, TLC, IR and 1H NMR spectroscopy.

Purple-coloured, tetra-coordinated Ni(II) complexes, Ni[S2P(OR)2]2 (R = o-, m-, p-OC6H4Me, Ph and CH2Ph) have been obtained by reaction of NiCl2 with salts of corresponding O,O′-diaryl(dibenzyl) dithiophosphates and have been characterized by elemental analysis, UV, IR, 1H, and 31P NMR spectroscopy. Trends in the data are discussed. The crystal structures of Ni[S2P(OC6H4Me-o)2]2, Ni[S2P(OC6H4Me-m)2]2 and Ni[S2P(OCH2Ph)2]2 are also described. Ni[S2P(OC6H4Me-o)2]2 crystallizes as monoclinic in the space group P21/n with cell parameters a = 9.069(2), b = 13.503(2), c = 23.735(4) A, α = 90.00°, β = 90.11(1)°, γ = 90.00°, V = 2906.6(8) A−3, Z = 4, R = 0.0351, Rw = 0.0787, Ni[S2P(OC6H4CH3-m)2]2 as triclinic in the space group P 1 ¯ with cell parameters a = 9.4675(4), b = 12.8568(5), c = 13.1174(6) A, α = 88.810(4)°, β = 83.416(5)°, γ = 73.711(4)°, V = 1522.4(1) A−3,Z = 2, R = 0.0354, Rw = 0.0830, and Ni[S2P(OCH2Ph)2]2 as triclinic in the space group P 1 ¯ with cell parameters a = 10.887(2), b = 14.081(3), c = 16.238(3) A, α = 72.70(3)°, β = 76.57(3)°, γ = 72.76(3)°, V = 2241.4(8) A−3, Z = 2, R = 0.0365, Rw = 0.0785. Each of these has a distorted square-planar geometry around nickel with MS4 coordination environment.

Bis(μ-sulfido)bis[{O,O-dimethyldithiophosphato}oxomolybdenum(V) was prepared by dropwise addition of an ethanolic solution of the ammonium salt of O,O-dimethyldithio-phosphoric acid to a hot aqueous solution of MoCl5. The X-ray structure of Mo2O2(Φ-S2)[S2P(OMe)2]2.C6H6 was determined. Crystal data: Monoclinic, P21/n, a = 6.9788(6), b = 22.616(3), c = 14.633(1) A, β = 101.193(9)°, V = 2265.5(4) A−3, Z = 4. The immediate environment around the two molybdenum atoms is essentially square pyramidal if the Mo—Mo interaction is ignored. The terminal oxygen atoms are in the syn conformation.

Two tellurium ligands 1-(4-methoxyphenyltelluro)-2-[3-(6-methyl-2-pyridyl)propoxy]ethane (L 1) and 1-ethylthio-2-[2-thienyltelluro]ethane (L2) have been synthesized by reacting nucleophiles [4-MeO-C6H4Te~] and [C4H3S-2-Te~] with 2-[3-(6-methyl-2-pyridyl)propoxy]ethylchloride and chloroethyl ethyl sulfide, respectively. Both the ligands react with HgBr2 resulting in complexes of stoichiometry [HgBr2AEL1/L2] (1/4), which show characteristic NMR (1H and 13C{1H}). On crystallization of 1 from acetone-hexane (2:1) mixture, the cleavage of L1 occurs resulting in 4-MeOC6H4HgBr (2) and [RTe+^HgBr2]Br~ (3) (where R = -CH2CH2OCH2CH2CH2-(2-(6-CH3-C5H3N))). The 2 is characterized by X-ray diffraction on its single crystal. It is a linear molecule and is the first such system which is fully characterized structurally. The Hg-C and Hg-Br bond lengths are 2.085(6) and 2.4700(7) A. The distance of four bromine atoms (3.4041(7)-3.546(7) A) around Hg (cis to C) is greater than the sum of van der Waal's radii 3.30 A. This mercury promoted cleavage is observed for an acyclic ligand of RArTe type for the first time and is unique, as there appears to

The reaction of ArTe- (Ar = 4-MeOC6H4) and Te2- generated in situ by borohydride reduction of Ar2Te2 and Te, respectively, with 2-(2-thienyl)ethyl chloride has resulted in 2-[2-(4-methoxyphenyltelluro)ethyl]thiophene (L-1) and bis[2-(2-thienyl)ethyl] telluride (L-2), respectively. Their complexes [AgNO3(L-1)] (1) [PdCl2(L-1)(2)] (2) [PtCl2(L-1)(2)] (3) [HgBr2(L-1)](2) (4) [Ru(p-cymene)Cl-2(L-1)] (5) [Ru(p-cymene)Cl-2(L-2)] (6) and [PdCl2(L-2)(2)] have been synthesized. The ligands and complexes exhibit characteristic H-1 and C-13{H-1} NMR spectra. Both the ligands coordinate only through Te in all the complexes. The single crystals of 2 and 6 are characterized by X-ray diffraction. Compound 2 has square planar geometry around Pd and trans arrangement of ligands. The Pd-Te bond distances 2.5951(7) and 2.5872(7) Angstrom are longer than the values expected due to strong trans influence. The unique intermolecular secondary Te...Cl interaction (distance = 3.450/3.449 Angstrom) between neighbouring molecules has been observed in the crystal structure of 2. The distance between Pd atoms of two neighbouring molecules 3.2143(10) Angstrom has also been found less than the sum of van der Waal's radii 3.26 Angstrom. These secondary interactions in 2 result in the formation of a dimeric species, which remains intact even in the solution. Compound 6 is a half sandwich having three coordination sites occupied by two Cl atoms and the Te atom of L-2 with Ru-Te bond distance of 2.6528(9) Angstrom and Ru-Cl, 2.415(2)/2.422(2) Angstrom.

Acyclic tellurated Schiff base [4-MeOC6H4TeCH2CH2N=C(CH3)C6H4-2-OH ((LH)-H-1)] has been synthesized by reacting 2-(4methoxyphenyltelluro)ethylamine with o-hydroxyacetophenone. The (LH)-H-1 on reaction with Na2PdCl4 forms a complex [PdCl(L-1)] in which the tellurated Schiff base coordinates in a tridentate mode. The proton and carbon-13 NMR spectra of (LH)-H-1 and the complex are characteristic. The single crystal structure of the complex is solved. The Pd-Te, Pd-Cl, Pd-O and Pd-N bond distances are 2.504(1), 2.290(4), 2.03(1) and 2.01(1) Angstrom, respectively.

Reactions of dichlorodioxobis(triphenylphosphine oxide)molybdenum(VI) complexes with ammonium/sodium salts of O; O-dialkyl(alkylene) and diphenyl dithiophosphoric acids in 1:l molar ratio in dichloromethane solution yield dioxomolybdenum complexes of the types. MOO,Cl[S2P(OR)(2)] . OPPh3 (R=Me, Et, i-Pr, Ph) and MoOiCl[S(2)POGO] . OPPh3. (G=-CH2CMe2CH2O-, -OCMe2)CMe2O-). These newly synthesized compounds were characterized by IR, UV-visible and H-1 NMR spectroscopy and elemental analysis. The molecular structure of MoO2Cl2(OSMe2)(2) was determined by single-crystal X-ray diffraction. MOO)Ch(OSMe2)(2) crystallizes as orthorhombic in the space group Pbca with cell parameters a = 13.7235(3) Angstrom, b = 12.2429(2) Angstrom, c = 14.3356(3) Angstrom, V = 2408.60(8) Angstrom(-3), Z = 8, R = 0.0221, R-w = 0.0519. There are two cis oxo ligands, two cis dimethylsulphoxide moieties and two tracts chlorine atoms in a distorted octahedral environment around molybdenum.

Methoxyphenyltelluro)-2-(3-(6 methyl-2 pyridyl)propoxy)ethane (L1) and its complexes (MCl2(L1))2 (M — Pd or Pt) have been synthesized. The single crystal X-ray diffraction of (PtCl2(L1))2 AE 2CHCl3 shows a bimetallic complex of platinum(II) containing a 20-membered metallomacrocycle ring, which remains stable in solution as shown by molecular weight and conductance mea- surements. The Pt-Te and Pt-N bond lengths are 2.5409(3) and 2.087(5) A, respectively. The protons of CH2 linked to Te show a deshielding > 1 ppm on the formation of the two complexes.

Reactions between Me3SbCl2 and K[(SPPh2)2N], using 1:1 and 1:2 molar ratios, have been investigated. In both cases Me-S-PPh2N-PPh2S (1) was isolated, as a result of the migration of a methyl group from antimony to sulfur. The S-Me ester was identified by NMR spectroscopy and its solid-state molecular structure was determined. Reaction of Me3SbCl2 and K[(OPPh2)(SPPh2)N] in 1:2 molar ratio gave Me3Sb[O-PPh2N-PPh2S]2 (2), isolated as a white solid and characterized by IR and NMR (1H, 13C, 31P) spectroscopy. The molecular structure of 2 was investigated by X-ray diffraction. The crystal consists of discrete molecules, with two monothio ligands bound to the metal center only through oxygen atoms, thus resulting in a trigonal bipyramidal C3SbO2 core. The SbC3 unit is planar [Σ(CSbC angles) 360°] and the angle between the axial SbO bonds is 173.4(2)°. The coordination of the monothioimododiphosphinato ligand in the O-monometallic monoconnective mode is unique; such ligands usually exhibiting chelate or bridging coordination through both oxygen and sulfur atoms.

Reactions of bis(N-phenylsalicylideneiminato)aluminium(III)di(mu-isopropoxo)di(isopro poxo) aluminium(III), [C6H4O{CH=N(C6H5)}](2)Al(mu-OPri)(2)Al(OPri)(2) (1) with simple and internally functionallized oximes in 1:1 and 1:2 molar ratios in refluxing anhydrous benzene yield binuclear complexes of the type, [C6H4O{CH=N(C6H5)}](2)Al(mu-OPri)(2)Al(ON=CRR')(OPri) and [C6H4O{CH=N(C6H5)}](2)Al(mu-OPri)(2)Al(ON-CRR')(2) [where R=R'=CH3; R=CH3, R=C4H3S-2, C4H3O-2 and C5H4N-2], respectively containing aluminium(III) atoms in six- and four-coordination sites. All these binuclear complexes are characterised by elemental analysis, molecular weight measurements and spectroscopy [IR and NMR(H-1, C-13 and Al-27)]. Reaction of bis(N-phenylsalicylideneiminato)(isopropoxo)aluminium(III) with 2-acetylthiophenyloxime in 1:1 molar ratio in refluxing anhydrous benzene, yields a novel heteroleptic compound, [C6H4O{CH=N(C6H5)}](2)Al{ON=C(CH3)C4H3S-2} (10). The crystal structure of [C6H4O {CH =N(C6H5)}](2)Al {ON =C(CH3)C4H3S-2} . CH2Cl2 shows five-coordination around the aluminium(III) atom.

Dimethlsulfoxide and dimethylformamide adducts of bis(mu-sulfido)bis[{O,O-dialkyldithiophosphato} oxomolybdenum(V)] of the type Mo2O2(Phi-S-2)[S2P(OR)(2)](2) . L (R=Me, Et and i-Pr; L=Me2SO and Me2NCHO) were prepared by the dropwise addition of a benzene solution of dimethylsulfoxide or dimethylformamide in excess to a 1:2 benzene-n-hexane solution of bis(mu-sulfido)bis[{O,O-dialkyldithiophosphato}oxomolybdenum(V)]. The compounds, Mo2O2(Phi-S-2)[S2P(OR)(2)](2) . L, were characterized by elemental analysis, IR. and H-1 and P-31 NMR spectroscopy. The crystal structures of Mo2O2(Phi-S-2)[S2P(OEt)(2)](2) . Me2SO, Mo2O2(Phi-S-2)[S2P{O(i-Pr)}(2)](2) . Me2SO and Mo2O2(Phi-S-2)[S2P{O(i-Pr)}(2)](2) . NC5H5 were determined. Mo2O2(Phi-S-2)[S2P(OEt)(2)](2) Me2SO crystallizes in the space group P2(1)/n, with cell parameters a=15.319(3) Angstrom, b=8.750(2) Angstrom, c=20.322(4) Angstrom, beta = 108.55(3)degrees, V=2582.5(9) Angstrom(-3), Z=4, R=0.0277 and R-w=0.0329. Mo2O2(Phi-S-2)[S2P{O(i-Pr)}(2)](2) . Me2SO crystallizes in the space group C2/c, with cell parameters a=29.848(6) Angstrom, b=8.566(2) Angstrom, c=12.328(3)Angstrom, beta=110.03(3)degrees, V=2961.2(10)Angstrom(-3), Z=4, R=0.0272 and R-w=0.0299. Mo2O2(Phi-S-2)[S2P{O(i-Pr)}(2)](2) . NC5H5 crystallizes in the space group P2(1)/n, with cell parameters a=9.210(2) Angstrom, b=28.859(6) Angstrom, c=12.421(3) Angstrom, beta=109.01(3)degrees, V=3121.5(11)Angstrom(-3), Z=4, R=0.0643 and R-w=0.1022. If the Mo-Mo interaction is ignored, the immediate environment about one of the Mo atoms in all three compounds is essentially a distorted octahedral with a very long Mo-O or Mo-N bond, while it is square-pyramidal about the other Mo atom. The terminal oxygen atoms are in the syn conformation. The dithiophosphate groups are bidentate in all complexes.

The reaction between Ph3SbBr2 and sodium salt of internally functionalized oximes in 1:2 molar ratio in refluxing anhydrous benzene afforded [Ph3Sb{ON=C(R)Ar}(2)] [R = CH3, Ar = C5H4N-2(1), C4H3S-2(2) C4H3O-2(3); R = H, Ar = C5H4N-2(4), C4H3S-2(5) and C4H3O-2(6)]. Treatment of (1) and (4) with 1 equiv. of Ph3SbBr2 yields the redistribution product [Ph3Sb(Br){ON=C(R)Ar}]. Controlled hydrolysis of (1) and (4) affords a species [Ph3Sb(OH){ON=C(R)Ar}]. All these complexes have been characterized by the elemental analyses, IR and NMR spectroscopic studies and in the case of I by single crystal X-ray diffraction studies. The structure of I features trigonal bipyramidal geometry around the antimony with the axial positions occupied by the two oxygen atoms of the oxime group [O(1)-Sb(1)-O(l)' 172.78(7)degrees] and equatorial positions by the phenyl groups.

Diorganotin(IV) complexes of the type [{R2Sn(ON=C(Me)py)}(2)O](2)(R = Bu-n(1), Pr-n(2), Et (3) and Me (4)) have been synthesized by the condensation reaction of R2SnO with 2-NC5H4(Me)C=NOH (5) in 1:1 molar ratio in refluxing anhydrous benzene-toluene and characterized by elemental analyses and IR and NMR (H-1, C-13 and Sn-119) spectroscopy. Two sets of Sn-119 chemical shifts are observed in the Sn-119-NMR spectra of all of these compounds indicating the presence of two types of environment around the tin atoms in solution. The crystal structures of 1, 3 and 5 have been established by single crystal X-ray diffraction, The bonding in 1 differs from that in 3 but in both structures two different environments around the tin atoms are evident with the geometry around each tin atom being that of a distorted trigonal bipyramid with alkyl groups at the equatorial positions. The structure of 5 consists of chains of molecules arising from intermolecular hydrogen bonding involving the nitrogen atom of the ring.

yThe reactions of N-(2-chloroethyl)benzamide and N-[3-bromopropyl]phthalimide with ArTe- Na+ generated in situ by borohydride reduction of Ar2Te2, have resulted in N-[2-(4-methoxyphenyltelluro)ethyl]benzamide (L-1) and N-[2-(4-methoxyphenyltelluro)propyl] phthalimide (L-2) respectively. The L-1 and L-2 both exhibit characteristic H-1 and C-13 NMR spectra. The single crystal structures of L-1 and L-2, the latter as a mixed crystal with (LH2)-H-2 are determined by X-ray diffraction (XRD). The Te-C(alkyl) bond length is 2.140(8)/2.149(4) Angstrom and longer than Te-C(aryl), 2.107(8)/2.123(5) Angstrom. The complexes having stoichiometries [PdCl2(L-1)] (1), [PtCl2(L-1)](2), [(Phen)Pd(L-1)](ClO4)(2) (3), [(DPPE)Pd(L-1)](ClO4), (4) and [RuCl2(L-2)(2)] (5) were synthesized and characterized by elemental analyses, conductance and molecular weight measurements, NMR (H-1 and C-13) and FT-IR spectra. The deshielding of CH2Te ( similar to 0.2 ppm in H-1 NMR and up to 22 ppm in C-13{H-1} NMR) and NH signals (upto 0.8 ppm in H-1 NMR) of 1 -4, with respect to those of free L-1 indicates that L-1 coordinates with Pd-Pt(II) as a (Te, N) ligand. The CH2Te/CH2N signals in H-1 and C-13 NNIR spectra of 5 appear deshielded (0.8/0.14 and 20/8 ppm, respectively), when compared with those of free L2, indicating ligation of L-2 via Te and N.

Triorganoantimony(V) complexes with internally functionallized oximes of the type [R3Sb{ONC(Me)Ar}2] (1) [R=Me, Pri; Ar=C5H4N, C4H3S, C4H3O] have been prepared by the reaction of R3SbBr2 with the corresponding oximes in 1:2 molar ratio in anhydrous benzene. Treatment of 1 with one equivalent of R3SbX2 afforded a redistribution product [R3Sb(X){ONC(Me)Ar}] (2) [X=(a):Br, (b):OH]. The species, R3Sb(OH)L, may also be obtained by the controlled hydrolysis of 1 (R=Pri; Ar=C5H4N). All of these complexes have been characterized by elemental analyses, and IR and NMR (1H and 13C) spectroscopic studies. Crystal structures of [Me3Sb{ONC(Me)C4H3O-2}2] (3), [Me3Sb{ONC(Me)C4H3S-2}2] (4) 2-OC4H3C(Me)NOH (5) and 2-SC4H3C(Me)NOH (6) are reported. The geometry around the antimony atom in 3 and 4 is distorted trigonal bipyramidal with the carbon atoms of the SbMe3 unit in equatorial positions and the two oxygen atoms of the oxime group occupying axial positions (O(1)SbO(2) 171.67(12) in 3 and 169.14(13) in 4). The free oxime is clearly hydrogen bonded (HN 2.08 A in 6) to essentially form a dimer.

[2-(Me2NCH2)C6H4]Se-S(S)PR2 [R = Ph (1), (OPr)-Pr-i (2)] were prepared by reacting [2-(Me2NCH2)C6H4](2)Se-2 with the appropriate disulfanes, [R2P(S)S](2). The compounds were characterized by multinuclear magnetic resonance (H-1, C-13, P-31). The molecular structures of 1 and 2 were determined by single-crystal X-ray diffraction. Both compounds are monomeric and the nitrogen atom of the pendent CH2NMe2 arm is strongly coordinated to the selenium atom. The organophosphorus ligands are monodentate, thus resulting in a T-shaped coordination geometry around selenium.

[2-(Me2NCH2)C6H4]TeS(S)PR2 [R = Me (2), Et (3), Ph (4), OPr' (5)] were prepared by reacting [2-(Me2NCH2)C6H4](2)Te-2 (1) with the appropriate disulfanes, [R2P(S)S](2), while [2-(Me2NCH2)C6H4]Te-S-PPh2=N-PPh2=S (6) was obtained by metathesis reaction between [2-(Me2NCH2)C6H4]TeBr and potassium tetraphenyldithioimidodiphosphinate. The compounds were characterized by multinuclear NMR (H-1,C-13, P-31). The crystal and molecular structures of 1, 2, 4-6 were determined by single-crystal X-ray diffraction. All compounds are monomeric and the N atom of the pendant CH2NMe2 arm is strongly coordinated to the tellurium atom. The organophosphorus ligands are monodentate, thus resulting in a T-shaped coordination geometry around tellurium.

Sodium telluride (Na2Te), obtained in situ by borohydride reduction of elemental tellurium, reacts with 2-(2-bromoethyl)-1,3-dioxane resulting in bis(2-{1,3-dioxan-2-yl}ethyl) telluride (L), which is isolated as an unstable viscous liquid. The potentially (Te,O-2) type of ligand L is stabilized on the formation of complexes [Ru(p-cymene)Cl2L] (1) and trans-[PdCl2(L)(2)] (2) which are characterized structurally. The Ru-Te bond length in the half sandwich compound I is 2.6559(9) A. The geometry of Pd in 2 is square planar. The Pd-Te bond length in 2 is 2.5873(2) A. 1 and 2 are the first examples of structurally characterized complexes in which potentially (Te,O-2) type ligand molecules are present, of course coordinating through Te only.

O-alkyl monothiocarbonate (monoxanthate) derivatives of tin were obtained by the reaction of a sodium salt of the monothiocarbonic acid with an organotin chloride to give Ph3Sn[SCO2R], Ph2Sn[SCO2R]2, and Me3Sn[SCO2R], where R = Me and i-Pr. The compounds have been characterized by infrared, Raman, 1H NMR, and 13C NMR spectroscopy, as well as mass spectrometry, and in two cases by X-ray crystallography. Ph3Sn[SCO2Me] (1) and Ph3Sn[SCO2(i-Pr)] (2), crystallize in the triclinic space group P[Formula: see text] (no. 2) with cell parameters a = 10.218(4), b = 10.568(6), c = 9.366(7) Å, α = 106.73(5), β = 96.99(5), γ = 85.55(4)°, V = 960(1) Å3, and Z = 2 for 1; and a = 14.793(2), b = 17.856(3), c = 9.813(3) Å, α = 103.86(5), β = 98.36(5), γ = 106.85(4)°, V = 2343(1) Å3, and Z = 2 for 2. The latter has two molecules in the asymmetric unit. The immediate environment about tin in both 1 and 2 is that of the expected distorted tetrahedron. However, the orientation of the monothiocarbonate group is such that there is an Sn-O intramolecular interaction of 3.040(8) for 1 and 3.05(2) Å on average for 2. Thus, the considerable distortion is consistent with a tendency to form a five-coordinate, trigonal bipyramidal species with one of the O-Sn-C angles approaching 180o (153.4(4) for 1 and an average of 157.1(6) for 2). Estimations of the Pauling partial bond orders suggest this weak Sn-O interaction is slightly stronger than the corresponding Ge-O interaction in the analogous germanium derivative, Ph3Ge[SCO2Me].Key words: structure, tin, methyl, phenyl, isopropyl, monothiocarbonates.

Ni[(OPR′2)(SPR2)N]2 complexes were obtained in good yields by reacting NiCl2·6H2O and the alkaline salts of the corresponding tetraorganomonothioimidodiphosphinic acids. All compounds were characterized by elemental analysis and IR. The molecular structure of Ni[(OPPh2)(SPR2)N]2 (R=Ph, Me) has been determined by single-crystal X-ray diffractometry. Ni[(OPPh2)-(SPPh2)N]2 (1) crystallizes in the monoclinic space group P21/c (no. 14), and Ni[(OPPh2)(SPMe2)N]2 (2) crystallizes in the triclinic space group P1 (no. 2). The crystals of both compounds contain discrete mononuclear molecules. The asymmetric ligands act as monometallic biconnective units which results in a tetrahedral NiO2S2 core.

The reaction of chloroform with ArTe− Na+ (Ar=4-MeOC6H4), generated in situ by borohydride reduction of Ar2Te2, results in a high purity sample of bis(4-methoxyphenyltelluro)methane (1) (yield ∼90%). Its single crystal structure has been reported. The TeCTe angle is found to be 117(1)°. The oxidative addition of I2 to 1 results in {4-MeO-C6H4Te(I2)}2CH2 (1a), which is also characterized structurally. The iodine atoms at each Te atom occupy axial positions. The two TeI bonds are longer than the other two. The intermolecular contacts of I(2) and I(4) with the neighbouring Te atoms lead to polymeric links of essentially TeITe′I′ rectangular bridges (angles 89.07(3)–94.68(3)°. The complexes of 1 with Ru(II) viz. cis-[Ru(DMSO)2Cl2(4-MeOC6H4Te)2CH2] (2) and [(p-cymene)Cl2Ru(μ-1)RuCl2(p-cymene)] (2a) are synthesized and characterized structurally. The geometry of Ru(II) in the complex 2 is distorted octahedral. (RuTe 2.5988(5)–2.6727(5) A; Te(1)Ru(1)Te(2)=78.2(2)°; Te(1)Ru(1)Cl(2)=76.6(2)°. The distortions are not shared equally by the two tellurium atoms. The Te(1) displays much larger distortions of cis angles than those involving Te(2). The TeC(aromatic) distances are shorter than TeC(alkyl) bond lengths. The 2a is the first example in which the ligand 1 is shown to coordinate in a bridging mode, i.e. with two Ru atoms (RuTe 2.6381(16)–2.6411(2) A). The Te(1)CTe(2) angle is 119.3(9)°. Similarly 2 is also the first example that has four membered chelate ring containing Ru and two Te atoms.

Manganese(II) compounds of the type Mn[(XPR2)(YPR′2)N]2 (X, Y=O, S; R, R′=Me, Ph), were prepared by metathesis reactions between MnCl2·4H2O and the alkaline salt of the corresponding ligand. IR data are consistent with the coordination of the phosphorus ligand in a deprotonated form. The ESR spectra exhibit resolved hyperfine structure only for the Mn[(OPMe2)(SPPh2)N]2 derivative. The crystal and molecular structures of Mn[(OPPh2)(YPPh2)N]2 (Y=O, S) were determined by X-ray diffractometry. The crystal of the tetraphenylthioimidodiphosphinato derivative contains monomeric, spiro-bicyclic Mn[(OPPh2)(SPPh2)N]2 units, with a distorted tetrahedral MnO2S2 core, as a result of monometallic biconnective phosphorus ligands. By contrast, in the crystal of the tetraphenylimidodiphosphinato analogue distinct [Mn{(OPPh2)2N}2]2 dimers are present, in which the MnO5 core has a trigonal bipyramidal geometry. The coordination pattern of the four imidodiphosphinato ligands differs. Two of them act as monometallic biconnective (chelating) units, leading to six-membered MnO2P2N rings. The other two ligands act as bimetallic triconnective units, which results in a fused tricyclic Mn2O4P4N2 system. The central four-membered Mn2O2 ring is slightly bent [Mn(1)O(5)O(8)/Mn(2)O(5)O(8) dihedral angle 23.9°]. The overall conformation of the [Mn{(OPPh2)2N}2]2 dimer might be described as cis, i.e. with six-membered MnO2P2N rings formed by ligands of the same type placed on the same side of the four-membered Mn2O2 ring.

The immediate environment about tellurium in Ph2Te[S2POCMe2CMe2O]2 (1) and 2Ph2Te[S2POCH2CMe2CH2O]2·2Ph2TeCl2·CS2 (2) is essentially that of a saw-horse structure in which the lone-pair is apparently stereochemically active and occupying an equatorial position in a distorted trigonal bipyramid. However, when the second sulfur atom of the unsymmetrical bidentate ligand is included in the coordination sphere, the arrangement about tellurium in compound 1 is better described as distorted octahedral and that in Ph2Te[S2POCH2CMe2CH2O]2 as distorted pentagonal pyramidal. An intermolecular association involving a chlorine atom of Ph2TeCl2 results in a pentagonal bipyramidal arrangement. Sulfur and chlorine bridges between the Te atoms of Ph2Te[S2POCH2CMe2CH2O]2 and Ph2TeCl2 indicate pseudo dimers or Te2S2Cl cages. The isolation of this mixed species rather than Ph2TeCl[S2POCH2CMe2CH2O] was most unexpected. There is no indication of hydrogen bonding in HS2POCMe2CMe2O (3) and HS2POCH2CMe2CH2O (4); even the shortest S–S internuclear distance, which is in compound 3, is 3.556(2) A. In both acids, the P–SH bond is significantly longer than the PS terminal bond.

Mixed ligand derivatives of Me2TeLL'2, where L = N,N-dialkyl dithiocarbamate or O,O-alkylene dithiophosphate and L' = O-alkyl dithiocarbonate, have been synthesized and characterized by elemental analysis, 1H, 13C, 31P, and 125Te NMR spectroscopy and infrared and Raman spectroscopy, and X-ray crystallography. Me2Te[S2CNMe2][S2COEt], 8: P[Formula: see text] (no. 2), with cell parameters a = 10.073(3) Å, b = 10.139(2) Å, c = 9.108(2) Å, α = 92.36(2)°, β = 115.55(2)°, γ = 111.19(2)°, V = 760.7(4) Å3, Z = 2, R = 0.0343, Rw = 0.0296. Me2Te[S2CNEt2][S2COMe], 9: P21/c (no. 14) with cell parameters a = 9.881(4) Å, b = 17.671(3) Å, c = 10.149(4) Å, β = 113.65(3)°, V = 1623.3(10) Å3, Z = 4, R = 0.0567, Rw = 0.0514. The immediate environment about tellurium in both molecules is essentially that of a saw-horse structure in which the lone pair is apparently stereochemically active and occupying an equatorial position in a distorted trigonal bipyramid. The S-Te-S angles in the two molecules are 166.87(6)° and 162.0(1)° for 8 and 9, respectively. In both molecules, the Te—S bonds to the dithiocarbamate groups are slightly shorter than those to dithiocarbonates. The dithiocarbamate groups are oriented to give secondary interactions involving the apparently terminal sulfur atoms resulting in Te—S distances of 3.205(2) and 3.277(4) Å, respectively, in 8 and 9. However, only in 9 is there a similar Te—S distance of 3.346(5) Å involving the S2COMe group because in 8, the OEt group of S2COEt, rather than the terminal S atom, is oriented toward Te. Key words: structure, tellurium, methyl, dithiocarbamates, dithiocarbonates, dithiophosphates.

On reacting [PbCl4]2- with bis(2-chloroethyl)amine, trans-[PdCl2{NH(CH2CH2Cl)2}2] (1) results selects selectively in high yield (∼80%). The structure of 1 has been solved by X-ray diffraction methods. The immediate environment about palladium is slightly distorted square planar, Pd-Cl bond lengths (2.297(1)/2.999(i)A) are in accordance with the trans-influence of various co-ligands. The Pd-N bond length is intermediate between Pd-NH3 and Pd-NMe2 bond distances. Attempts to substitute the Cl atom of the alkyl chain by nucleophile ArTe-leads to dissociaton of the complex resulting in Pd(TeAr)2 and NH(CH2CH2TeAr)2.

On reacting 1,2-bis(diphenylphosphino)ethanedichloropalladium(II) with equimolar amount of silver perchlorate, a binuclear complex, di-μ-chloro-bis[1,2-bis(diphenylphosphino)ethane-palladium(II)] (1) is formed. The crystal structure of 1 has been solved. It crystallizes with two chloroform molecules. Chloro bridges are symmetrical and normal (Pd-Cl∼2.414(3) A). The immediate environment around palladium is slightly distorted square planar and the P-Pd-P angle is ∼85°. IR bands at 290 and 270cm−1 are observed for the chloro-bridged core of the complex.

Thermolytic reaction of Cp2Mo2Fe2STe(CO)7 and C6H5SH in benzene afforded two isomers of the new compound Cp2Mo2Fe2(μ3-S)(μ3-Te)(μ2-SPh)(μ3-H)(CO)5 in 23 and 21% yields. They were characterised by IR, 1H- and 125Te-NMR spectroscopy. The structure of one isomer was established by single crystal X-ray diffraction method. The structure consists of a Mo2Fe2 tetrahedron with μ3-S and μ3-Te face capping ligands. The Mo–Mo bond is bridged by a SPh group and one MoFe2 face is bridged by a μ-H group. Each Fe atom has two terminal carbonyls and one CO group bridges the Fe–Fe bond., © Elsevier

The compound NH(SPMe2)(SPPh2) was prepared using a new method, i.e. the reaction between Li[HN(S)PPh2] and Me2P(S)Cl in a diethyl ether–n-hexane mixture. The complex [Co{(SPMe2)(SPPh2)N}2] was obtained by the reaction of CoCl2·6H2O and K[(SPMe2)(SPPh2)N] in methanol. The crystal and molecular structure of both the free acid NH(SPMe2)(SPPh2) and its cobalt(II) complex [Co{(SPMe2)(SPPh2)2N}2] were determined using X-ray diffractometry. The acid exhibits an anti conformation of the sulfur atoms in the SPNPS system and dimeric pairs are formed in the crystal through N(1)–H(1)· · ·S(2a) [2.43(9) A] hydrogen bonds, which involve only the sulfur atom of the SPPh2 group of each molecule. The cobalt complex consists of discrete, monomeric molecules, with isobidentate ligands [average Co–S 2.32(1), average P–S 2.031(5) A] and a distorted tetrahedral CoS4 core (S–Co–S range 102.7–117.7°). The structures of both the free acid and its cobalt(II) derivative are discussed in relation with other bis(thiophosphinoyl)amines and metal complexes containing a CoS4 core.