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The synthesis and characterization of a series of SPS–Ni(II) pincer complexes with different para-substituted triphenylphosphines has been performed. The molecular structure of [Ni(phPS2)(PPh3)] (1) (phPS2H2 = PhP(C6H4-2-SH)2, bis(phenyl-2-thiol)phenylphosphine) was unequivocally determined by single crystal X-ray diffraction analysis. The metal centre exhibited a slightly distorted square planar geometry. The complexes showed a high catalytic activity in the C S cross-coupling reaction of both alkyl- and aryl-disulfides with iodobenzenes for the production of non-symmetric sulfides. In general, the different para-substituted triphenylphosphine ligands do not affect the catalytic performance of the SPS–Ni(II) complexes. However, activity of the catalyst decreases with the steric hindrance of the different alkyl groups in the disulphide substrates.

Four new stibocanes substituted with cyclic dithiophosphate ligands O(CH2CH2S)2SbS2P(OCH2)2CEt2 (1), O(CH2CH2S)2SbS2P(OCH2)2C(Me)Pr (2), S(CH2CH2S)2SbS2P(OCH2)2CEt2 (3) and S(CH2CH2S)2SbS2P(OCH2)2C(Me)Pr (4) were prepared from the corresponding chloro oxa- and thia-stibocanes and the sodium salt of the dithiophosphoric acids 5,5-diethyl-(2-mercapto-2-thiono-1,3,2-dioxaphosphinane) and 5-methyl-5-propyl-(2-mercapto-2-thiono-1,3,2-dioxaphosphinane) in ethanol. The compounds obtained were characterized by IR, EI-MS and multinuclear NMR (1H, 13C, 31P) spectroscopies. The single-crystal structures of 1 and 2 were determined which show the presence of three types of secondary bonding: i.e. strong Sb- - -O transannular interactions of 2.607(4) and 2.600(4) A, respectively, anisobidentate coordination of the ligand (exocyclic chelation) average Sb- - -S distance 3.355 A and intermolecular interactions that lead to supramolecular associations. The coordination geometry around antimony atom in both 1 and 2 can be described as Ψ tricapped trigonal bipyramidal AB4CD2E. The eight membered ring presents a boat-chair conformation in both compounds and the 1,3,2-dioxaphosphinane ring has the chair conformation, with the stibocane in the axial position.

[D(CH2CH2S)2]M(XCH2CH2Y) 1–8 (M = Ge, Sn; D = O, S; X = Y = S, O and X = S, Y = O) spirocycles were synthesized to analyze the influence of the metal center replacement and the donor atom hardness on the strength of the transannular bond and the hypercoordination phenomena. The compounds were characterized by IR, Raman and NMR (1H, 13C and 119Sn) spectroscopy, E.I. mass spectrometry and elemental analysis. The molecular and crystal structures of compounds 3, 4, 6–8 and Ge(SCH2CH2S)2 (9) were obtained by X-ray diffraction analyses. They all exhibit five-coordinate central atoms due to transannular metal coordination (M ⋯ D) except 4, which displays a dimeric structure formed by the fusion of two five-membered rings resulting in a cyclic-distannoxane unit, {[O(CH2CH2S)2]Sn(SCH2CH2O)}2. The relationship between the nature of the metal center and the differences found between the two germanium and tin series are discussed.

D(CH2CH2S)2MSNH(C6H4) (M = Ge, Sn; D = O, S) spirocycles were synthesized to analyze the influence of the decrease of the radius of the metal and the change of the hardness of donor atom on the strength of the transannular bond and the hypercoordination of group 14 elements. The compounds were characterized by IR, Raman and NMR (1H, 13C and 119Sn) spectroscopy, EI mass spectrometry and elemental analysis. Monocrystal X-ray diffraction analyses were made for the germanium compounds. The germaspirocycles were five-coordinated and had distorted trigonal bipyramid geometry. In contrast with most of the reported analogous germocanes, the transannular bond is stronger when the donor atom is oxygen, rather than sulfur. O(CH2CH2S)2GeSNH(C6H4) exhibits an intramolecular hydrogen bond formation between the amine group and the transannular oxygen. The presence of this hydrogen bond determines whether the sulfur (O⋯Ge–S) or the nitrogen (S⋯Ge–N) of the five-member ring is the axial atom. According to the 119Sn chemical shift, both stannospirocycles were five-coordinated and therefore the presence of the transannular interaction in solution could be suggested.

Condensation of aminoguanidine with 2-formylpyridine, 2-benzoylpyridine and 2,6-diacetylpyridine results in the aminoguanidones, HFogu, HBzgu and H22,6Acgu2, respectively. Reaction of the heterocyclic aminoguanidone in a mixture of hydrochloric acid–ethanol with copper(II) chloride produces the following mixed salts: [H3Fogu][CuCl4], (1), [H3Bzgu]2 [CuCl4]Cl2·H2O, (2), and [H52,6Acgu2][CuCl4]Cl·H2O, (3). Their crystal structures, as well as their ESR and UV spectra, have been obtained. The influence on the geometry of the [CuCl4]2− of the NH⋯ClCu hydrogen bonds, in the context of charged compensation hypothesis, has been evaluated.

The multidentate ligand, 2,6-diacetylpyridine bis(3-hexamethyleneiminylthiosemicarbazone) monohydrate, H22,6Achexim·H2O, crystallizes with one thiosemicarbazone moiety in an intramolecular hydrogen bonded, bifurcated E′ form. The other thiosemicarbazone moiety is E and is not involved in intramolecular hydrogen bonding, but is involved in hydrogen bonding with the hydrate water molecule. The dianion (loss of N3a and N3b hydrogens) of H22,6Achexim acts as a pentadentate ligand, 2,6Achexim, in a planar conformation to a central tin(IV) ion, and as a bridging tetradentate ligand with the two thiosemicarbazone moieties of 2,6Achexim coordinating to different zinc atoms. The tin(IV) is heptacoordinate in a distorted pentagonal dipyramidal configuration, with the five SNNNS donor atoms of 2,6Achexim in the pentagonal plane and the two n-butyl groups in the axial positions. The binuclear zinc complex has two equivalent tetrahedral zinc centers, with the pyridyl nitrogens of the two ligands not coordinated.

Reduction of 2-cyanopyridine by sodium in dry methanol in the presence of N(4)-methylthiosemicarbazide produces 2-pyridineformamide N(4)-methylthiosemicarbazone, HAm4M. Complexes with iron(III), cobalt(II,III) and nickel(II) have been prepared and characterized by molar conductivities, magnetic susceptibilities and spectroscopic techniques. In addition, the crystal structures of HAm4M, [Ni(Am4M)(OAc)], [Fe(Am4M)2]ClO4 and [Co(Am4M)2]ClO4 have been solved. Coordination is via the pyridyl nitrogen, imine nitrogen and thione or thiolato sulfur when coordinating as the neutral and anionic ligand, respectively.

The reaction between [Mn (CO) 5 ] Br and Na [ (OPPh 2 ) 2 N] in argon atmosphere affords the preparation of Mn (CO) 4 [ (OPPh 2 ) 2 N] as a white powder. During attempts to grow X-ray diffraction quality crystals the tetracarbonylmanaganese (I) complex was oxidized and deep purplish-blue crystals were isolated. An X-ray diffractometry analysis has revealed the identity of the new product, i.e. the manganese (III) derivative, Mn [ (OPPh 2 ) 2 N] 3 · CH 2 Cl 2 . The compound crystallizes in the triclinic space group P -1 and the crystal contains discrete, monomeric molecules of Mn [ (OPPh 2 ) 2 N] 3 . The imidodiphosphinato groups are coordinated through both oxygen atoms of a ligand moiety to the central manganese atom. The resulted coordination octahedron exhibits a tetragonally elongated distortion as reflected by the Mn — O bond lengths [av. 2.130 (16) , 1.945 (6) A] and cis O — Mn — O bond angles [endocyclic (av.) 90.5 (0.6) ° ; exocyclic (range) 87.2 (0.1) –92.7 (0.1) °] . The structure of the title compound is compared with those of other monomeric manganese (III) derivatives containing MnO 6 cores with various degrees of distortion.

A new method of synthesis, i.e. the reaction between Li[HN(S)PPh 2 ] and Ph 2 P(O)Cl in a diethyl ether/ n -hexane mixture, was used for the preparation of tetraphenylmonothioimidodiphosphinic acid. Its sodium salt was obtained by reacting the free acid with NaH in THF. The solid state structures of both compounds were determined by X-ray crystallography. (OPPh 2 )(SPPh 2 )NH ( 1 ) contains two independent molecules in the unit cell. Both molecules exhibit an anti conformation of the chalcogen atoms in the OPNPS system. In the crystal the molecules of 1 are associated into polymeric chains through hydrogen bonds involving only the oxygen atoms of each molecule [av. (N )H/3.O 2.09A]. the sodium salt of this acid can be considered to be built up of centrosymmetric dimers [Na(OPPh 2 )(SPPh 2 )N · 2THF] 2 ( 2 ). The O atom of the ligand unit acts as a bridging between the two Na atoms of the dimer [Na(1) O(1) 2.245(9), Na(1) O(1)′ 2.396(9)A]. In addition Na(1) is also coordinated by the S(1)′ atom [Na(1) S(1)′ 2.975(6)A] and the oxygen atoms of the two THF molecules [Na(1) O(2) 2.37(1), Na(1) O(3) 2.35(1)A]. This results in a trigonal bipyramidal geometry around sodium atoms [O(1)′ and O(3) in axial positions for Na(1), O(3) Na(1) O(1)′ 171.5(4)°], and a tricyclic system with a central planar four-membered Na 2 O 2 ring.

Copper(II) and nickel(II) complexes of 2,3-butanedione bis(N(3)-methyl-, bis(N(3)-dimethyl-, bis(pyridyl- and bis(hexamethyleneiminylthiosemicarbazone), (H2Bu3M, H2Bu3DM, H2Bupip and H2Buhexim, respectively) have been prepared and studied spectroscopically. The four thiosemicarbazones have been characterized by their melting points, as well as IR, electronic and NMR (1H, 13C) spectra. The four coordinate copper(II) complexes have been studied by EPR spectroscopy and the copper(II) and nickel(II) complexes by a number of the spectroscopic techniques mentioned above. Upon formation of these complexes, loss of the N(2)H hydrogens occurs and the ligands coordinate to the metal centers as dianionic, tetradentate N2S2 ligands. The crystal structures of H2Bupip and the nickel(II) complex of 2,3-butanedione N3-methyl-phenylthiosemicarbazone, [Ni(Bu3MPh)], have been solved.

A series of N(4)-substituted thiosemicarbazones of isatin were synthesized and their copper(II) complexes prepared from copper(II) chloride. X-ray crystal structures of two of the thiosemicarbazones, isatin 3-(hexamethylenimylthiosemicarbazone) and isatin 3-(N(4)-ethylthiosemicarbazone), have been solved and are compared with a previously published structure of isatin 3-(N(4)- p -tolythiosemicarbazone). The coordination chemistry of the copper(II) complexes of these and other isatin thiosemicarbazones is reported and discussed.

Anions [loss of N(3) hydrogen of 2-acetylpyridine N(4)-dimethylthiosemicarbazone (HAc4DM)] coordinate in a planar conformation to a central palladium(II) through the pyridyl nitrogen, azomethine nitrogen and thiolato sulfur atoms. The fourth coordination site is occupied by either a bromo, chloro or a second Ac4DM ligand bonding via its thiolato sulfur atom. A crystal structure of [Pd(Ac4DM)Br] shows it to be planar, while the structure of [Pd(Ac4DM)2] has the unusual coordination of the two anions bonding differently to the palladium centre. Spectral and structural similarities and differences between these and related nickel(II) and copper(II) complexes are considered.

Three structural forms have been isolated among four 2-formyl- and 2-acetylpyridine N(4)-substituted thiosemicarbazones reported. 2-Formylpyridine N(4)-methylthiosemicarbazone and 2-acetylpyridine N(4)-ethylthiosemicarbazone both exist as nonhydrogen bonding E isomers. 2-Formylpyridine 3-azabicyclo[3.2.2]nonylthiosemicarbazone crystallies as a hydrogen bondung Z isomer. The yellow 2-acetylpyridine 3-hexamethyleneiminylthiosemicarbazone crystallized with a bifurcated hydrogen bonding arrangement in which the N(3) hydrogen is formally positioned at N(2), making it tautomeric to the other two forms. Structures of four-coordinate nickel(II) complexes containing the monoanions of 2-formylpyridine 3-azabicyclo[3.2.2]nonylthiosemicarbazone and acetylpyrazine 3-hexamethyleneiminylthiosemicarbazone are included.

The structure of [Ph3PNPPh3]+[SPh2PNPPh2S]− was determined by single crystal X-ray diffraction. The cation displays the usual bent conformation [PNP 143.0(5)°] and long PN bonds (1.577(3) A). This salt represents the first example of a linear SPh2PNPPh2S− anion (PNP 180°) with short PN bonds [1.554(2) A]. The structures of the bent and linear forms of the [Ph3PNPPh3]+ cation and [SPh2PNPPh2S]− anion can be rationalized in terms of PN single and double bond contributions to the resonance structures describing them.

The title compounds, prepared from X(CH2CH2SNa)2 (X = S, O) and SnCl4 were investigated by X-ray diffraction. In both compounds transannular secondary Sn⋯X interactions in the eight-membered rings produce a distortion of the SnS4 tetrahedron. This consists of an enlargement of SSnS angle [to 126.1° when X = S and 118.9° (118.4°) when X = O] with simultaneous decrease of the opposite tetrahedral angle [to 93.2° when X = S and 94.4° (93.2°) when X = O]. The coordination geometry in both compounds can be described as based upon a bicapped tetrahedron.