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Two pseudo-para substituted bis-diimino[2.2]paracyclophane ligands (4,16-bis(picolinaldimine)-[2.2]paracyclophane (BPPc) and 4,16-bis(methyl-picolinaldimine)-[2.2]paracyclophane (BmPPc)) were prepared by the condensation reaction of the appropriate picolinaldimine with 4,16-diamino-[2.2]paracyclophane (2). An improved synthesis of 2 from [2.2]paracyclophane also is reported. BPPc (3a): monoclinic, P2(1)/c, a = 8.2238(11) A, b = 15.336(2) A, c = 8.4532(11) A, beta = 98.578(3) degrees, V = 1054.2(2) A(3), Z = 2. To investigate the binding properties of the bis-diimino[2.2]paracyclophane ligands, binuclear rhenium(I) tricarbonyl chloride complexes [Re(CO)(3)Cl](2)(micro-BPPc) (5a) and [Re(CO)(3)Cl](2)(micro-BmPPc) (5b) were prepared and fully characterized by infrared spectroscopy, (1)H NMR spectroscopy, elemental analysis, UV-visible absorption spectroscopy, and cyclic voltammetry. Two model complexes, Re(tolyl-pyCa)(CO)(3)Cl (4) (tolyl-pyCa = N-(p-tolyl)-2-pyridinecarboxaldimine) and [Re(CO)(3)Cl](2)(micro-PBP) (6) (PBP = p-phenylenebis(picolinaldimine)), also are reported. The dimeric compounds 5 and 6 each undergo two one-electron, predominantly diimine-centered reduction processes. Spectroscopic data and comproportionation constants (5a, 23 +/- 9; 5b, 23 +/- 9; 6, 2750 +/- 540) are consistent with relatively weak interactions between the diimine groups mediated by the paracyclophane bridging group, and these results are consistent with steric and electronic factors.

The diamagnetic square planar d(8) complexes [meso-arylcorrolato]copper(III) become paramagnetic upon warming, indicative of the equilibrium between the [corrolato]copper(III) and the [corrolato](+)* copper(II) forms of the complex. [meso-Triphenylcorrolato]copper(III) was structurally characterized and found to be saddled.

A strategy for designing cooperative outer-sphere two-electron platinum reagents is demonstrated. The novel platinum(II) complex, [Pt(tpy)(pip2NCN)][BF4] (1(BF4-)) (tpy = 2,2':6',2' '-terpyridine, pip2NCN- = 2,6-(CH2N(CH2)5)2-C6H3-), in which the metal is bonded to two pincer type ligands, has been prepared. Treatment of 1 with protic acid results in protonation of the pendant piperdyl groups, allowing for the isolation of [Pt(tpy)(pip2NCNH2)][PF6]3 (2(PF6-)3). 1H NMR spectra of 1 and 2 establish that in each complex the terpyridyl ligand is tridentate, whereas the piperdyl ligand is monodentate, bonded to platinum through the phenyl ring. The structure of the protonated complex was confirmed by an X-ray crystallographic study of crystals of 2(Cl-)3.4H2O. The cyclic voltammagram of 1 exhibits two reversible one-electron reduction waves at E degrees ' = -0.98 V and E degrees ' = -1.50 V (E degrees ' = (Epc + Epa)/2), with a DeltaEp of 65 and 61 mV, respectively. In contrast to other Pt(II) complexes, including 2, this complex also undergoes a nearly reversible two-electron oxidation process at E degrees ' = 0.40 V (DeltaEp = 43 mV, 0.01 V/s). The accumulated data are consistent with the unusual ligand architecture of 1 being capable of stabilizing and allowing for facile interconversion between the Pt(II) and Pt(IV) oxidation states.

The structure of [PPh(3)(benzyl)][B(10)H(11)] was determined at -123 degrees C and 24 degrees C by single-crystal X-ray analyses. The B(10) core of [B(10)H(11)](-) is similar in shape to that of [B(10)H(10)](2)(-). The 11th H atom asymmetrically caps a polar face of the cluster and shows no tendency for disorder in the solid state. Variable temperature multinuclear NMR studies shed light on the dynamic nature of [B(10)H(11)](-) in solution. In addition to the fluxionality of the cluster H atoms, the boron cage is fluxional at moderate temperatures, in contrast to [B(10)H(10)](2)(-). Multiple exchange processes are believed to take place as a function of temperature. Results of ab initio calculations are presented. Crystal data: [PPh(3)(benzyl)][B(10)H(11)] at -123 degrees C, P2(1)/c, a = 9.988(2) A, b = 18.860(2) A, c = 15.072(2) A, beta = 107.916(8) degrees, V = 2701.5(7) A(3), Z = 4; [PPh(3)(benzyl)][B(10)H(11)] at 24 degrees C, P2(1)/c, a = 10.067(5) A, b = 19.009(9) A, c = 15.247(7) A, beta = 107.952(9) degrees, V = 2775(2) A(3), Z = 4.

The Au...Au distance in the title compound, [Au(2)Cl(2)(C(30)H(24)P(2))], is 2.996 (1) A, typical of an Au...Au interaction. The two P-Au-Cl arms 'cross' at the Au centers, with a Cl-Au...Au-Cl torsion angle of -63.92 (7) degrees. Only a small deviation from linearity is observed in the coordination around the Au atoms. Related phosphine-gold(I) chloride structures with intra- and intermolecular Au...Au interactions are surveyed.

A new series of square planar Pt(II) complexes with the mer-coordinating tridentate ligand, pip(2)NCN(-) (pip(2)NCNH = 1,3-bis(piperdylmethyl)benzene), has been prepared: Pt(pip(2)NCN)Cl (2), Pt(pip(2)NCN)Br (3), Pt(pip(2)NCN)I (4), and [Pt(pip(2)NCN)(CH(3)N=C(CH(3))(2))][CF(3)SO(3)] (5). The complexes have been fully characterized by (1)H NMR spectroscopy, elemental analysis, and UV-vis spectroscopy. The X-ray crystal structures of pip(2)NCNBr (1), 2, and 5 are reported. Compound 1: triclinic, P, a = 10.081(1) A, b = 10.153(2) A, c = 10.390(1) A, alpha = 66.05(1) degrees, beta = 79.07(1) degrees, gamma = 64.51(1) degrees, V = 877.1(2) A(3), Z = 2. Complex 2: triclinic, P, a = 9.897(2) A, b = 10.191(2) A, c = 19.174(4) A, alpha = 75.09(3) degrees, beta = 76.14(3) degrees, gamma = 71.00(3) degrees, V = 1741.2(6) A(3), Z = 4. Complex 5: triclinic, P, a = 10.709(2) A, b = 11.2321(10) A, c = 12.447(2) A, alpha = 110.509(8) degrees, beta = 112.417(10) degrees, gamma = 91.066(9) degrees, V = 1276.1(3) A(3), Z = 2. In 77 K 3:1 EtOH/MeOH glassy solution, these colorless complexes exhibit weak red-orange to red emissions originating from a lowest spin-forbidden ligand field excited state.

The molecular structure of the title compound involves a carboxylate group acting as a bidentate ligand to one rhenium atom, while acting as a monodentate ligand to the other rhenium atom. It was prepared in a one-step reaction by treating a THF solution of fac-(dppp)(CO)3ReCO2H with solid KOH.

Pyridylmethylthiourea derivatives coordinate with [(en)2Co(OSO2CF3)2]+ in a tridentate manner resulting in the formation of a hypodentate ethylenediamine ligand. Four ligands were studied: N-(R)phenyl-N′-2-pyridylmethylthiourea (R = H (1a), CH3 (1b), OCH3 (1c)) and N-benzyl-N′-2-pyridylmethylthiourea (2). These bind through the sulfur, a deprotonated exo nitrogen, and the pyridyl nitrogen atoms forming four and five-membered rings, respectively. The ligand also coordinates in a bidentate manner through the sulfur and deprotonated endo or exo nitrogen atoms, forming two additional coordination isomers. The solid state structure (X-ray) of one of the bidentate isomers of Co-1b2+ (endo isomer) shows that the coordinated thiourea sulfur induces a structural trans effect of 0.035 Å on the trans Co–N bond while that of the tridentate isomer of Co-1a3+ confirms the coordination mode of the ligand and the presence of a protonated hypodentate ethylenediamine ligand as suggested by 1H and 13C NMR spectroscopy.

[reaction: see text] Selective excitation of the ketone chromophore in alpha-azidoacetophenones, 1, leads to intramolecular triplet energy transfer to the azido group, which forms the corresponding triplet alkyl nitrene, 2. Azides 1 also undergo alpha-cleavage to form benzoyl and methyl azido radicals in competition with nitrene formation. Thus the major photoproduct, 2-benzoylamino-1-phenylethanone, 3, comes from trapping of 2 with a benzoyl radical. This appears to be the first observation of bimolecular trapping of triplet alkyl nitrenes in solution.

Nickel hydride with a diphosphinite-based ligand catalyzes the highly efficient reduction of CO(2) with catecholborane, and the hydrolysis of the resulting methoxyboryl species produces CH(3)OH in good yield. The mechanism involves a nickel formate, formaldehyde, and a nickel methoxide as different reduced stages for CO(2). The reaction may also be catalyzed by an air-stable nickel formate.

The noteworthy structural feature of the title complex, poly[acetonitriletetra-μ2-thiocyanato-barium(II)digold(I)], {[Au2Ba(SCN)4(CH3CN)]}n, is that the bis(thiocyanato)aurate(I) anion adopts both monomeric and trimeric motifs. The trimer unit has an Au...Au distance of 3.1687 (3) Å. In both the monomeric and trimeric units, the AuI atoms are also bonded to two S atoms. Within the trimeric unit, the AuI atoms exist in differing environments; one Au atom has a T-shaped three-coordinate geometry while the other has a square-planar four-coordinate geometry. The AuI atom of the monomer adopts a linear two-coordinate geometry. The extended structure can be described as a three-dimensional coordination polymer consisting of chains of Ba atoms bridged by thiocyanate N atoms. These chains are cross-linked via the gold monomeric and trimeric units.

C 12 H 3 ClO 11 Os 3 cristallise dans P2 1 /c avec a=8,028, b=17,602, c=13,805 A, β=104,88°, Z=4; affinement jusqu'a R=0,021. La structure moleculaire du compose comprend un triangle O s , doublement ponte sur un cote par un coordinat hydride et un coordinat halogenomethoxy

Ruthenium red is a well known inhibitor of Ca2+ uptake into mitochondria in vitro. However, its utility as an inhibitor of Ca2+ uptake into mitochondria in vivo or in situ in intact cells is limited because of its inhibitory effects on sarcoplasmic reticulum Ca2+ release channel and other cellular processes. We have synthesized a ruthenium derivative and found it to be an oxygen-bridged dinuclear ruthenium amine complex. It has the same chemical structure as Ru360 reported previously (Emerson, J., Clarke, M. J., Ying, W-L., and Sanadi, D. R. (1993) J. Am. Chem. Soc. 115, 11799-11805). Ru360 has been shown to be a potent inhibitor of Ca2+-stimulated respiration of liver mitochondria in vitro. However, the specificity of Ru360 on Ca2+ uptake into mitochondria in vitro or in intact cells has not been determined. The present study reports in detail the potency, the effectiveness, and the mechanism of inhibition of mitochondrial Ca2+ uptake by Ru360 and its specificity in vitro in isolated mitochondria and in situ in isolated cardiac myocytes. Ru360 was more potent (IC50 = 0.184 nM) than ruthenium red (IC50 = 6.85 nM) in inhibiting Ca2+ uptake into mitochondria. 103Ru360 was found to bind to isolated mitochondria with high affinity (Kd = 0.34 nM, Bmax = 80 fmol/mg of mitochondrial protein). The IC50 of 103Ru360 for the inhibition of Ca2+ uptake into mitochondria was also 0.2 nM, indicating that saturation of a specific binding site is responsible for the inhibition of Ca2+ uptake. Ru360, as high as 10 microM, produced no effect on sarcoplasmic reticulum Ca2+ uptake or release, sarcolemmal Na+/Ca2+ exchange, actomyosin ATPase activity, L-type Ca2+ channel current, cytosolic Ca2+ transients, or cell shortening. 103Ru360 was taken up by isolated myocytes in a time-dependent biphasic manner. Ru360 (10 microM) applied outside intact voltage-clamped ventricular myocytes prevented Ca2+ uptake into mitochondria in situ where the cells were progressively loaded with Ca2+ via sarcolemmal Na+/Ca2+ exchange by depolarization to +110 mV. We conclude that Ru360 specifically blocks Ca2+ uptake into mitochondria and can be used in intact cells.

A nickel-based catalytic system has been developed for [2 + 2 + 2] cyclotrimerization of various alkynes, especially ynoates. This catalytic system enables facile construction of substituted aromatic compounds in excellent yields with high regioselectivity.

[Pt(tpy)Cl]ClO4·H2O (1·H2O) changes from red to yellow upon dehydration due to increased Pt···Pt distances. Spectroscopic, diffraction, gravimetric and calorimetric data demonstrate the presence of intermediates during hydration and dehydration which signifies surprising mechanistic complexity in the vapochromic response.

Reaction of known meso-tetraarylporpholactone free bases 3, made from the corresponding porphyrins, with hydrazine produces three products: It converts the lactone functional group into an N-aminolactam moiety, generating porphyrin-like N-aminoporpholactams 8. It also reduces regioselectively the β,β'-double bond of the pyrrolic moiety opposite to the imidazolone in both the starting material and the N-aminoporpholactam, thus forming the chlorin-like chlorolactones 7 and N-aminochlorolactams 9. An equivalent set of reaction products is also derived from the reaction of porpholactones 3 with tosylhydrazide. Reductive N-N cleavage of the N-aminoporpholactams 8 generated the parent porpholactams 10. The molecular structures of all key compounds were shown by single crystal X-ray diffraction to be essentially planar. Porpholactam 10a can be converted in two steps (enolization and halogenation α to the imine, followed by reductive removal of the halogen) to known imidazoloporphyrin 5a, thus constituting the third independent pathway to replace a β-carbon of a tetraphenylporphyrin by a nitrogen. All these transformations show the flexibility of our 'porphyrin breaking and mending' strategy toward the synthesis of novel porphyrin and chlorin analogues incorporating non-pyrrolic heterocycles that carry functionalities at their periphery.

The title complex, C14H11ClN2S2, is an example of a push–pull buta­diene. Typical π-electron delocalization along the buta­diene moiety, influenced by the donor and acceptor groups, is observed.

A series of bis(thiocyanato)gold(I) complexes with Au-Au interactions show luminescence in the range from 500 to 670 nm. The series of salts correlates emission energy with the reciprocal of the Au-Au distance. As the Au-Au distance increases, the emission energy decreases. The ligand system provides no framework for the Au-Au interaction. The emission energy seems totally determined by the Au-Au distance.

The title compound, [Fe([9]­aneS3)2](ClO4)2 or [Fe(C4H8S2)3](ClO4)2, contains an octahedral FeIIS6 core, with the Fe atom located on an inversion center. The asymmetric unit comprises two independent half cations and two anions.

Pincer complexes of the type [2,6-(R(2)PO)(2)C(6)H(3)]NiSC(6)H(4)Z (R = Ph and i-Pr; Z = p-OCH(3), p-CH(3), H, p-Cl, and p-CF(3)) have been synthesized from [2,6-(R(2)PO)(2)C(6)H(3)]NiCl and sodium arylthiolate. X-ray structure determinations of these thiolate complexes have shown a somewhat constant Ni-S bond length (approx. 2.20 Å) but an almost unpredictable orientation of the thiolate ligand. Equilibrium constants for various thiolate exchange (between a nickel thiolate complex and a free thiol, or between two different nickel thiolate complexes) reactions have been measured. Evidently, the thiolate ligand with an electron-withdrawing substituent prefers to bond with "[2,6-(Ph(2)PO)(2)C(6)H(3)]Ni" rather than "[2,6-(i-Pr(2)PO)(2)C(6)H(3)]Ni", and bonds least favourably with hydrogen. The reactions of the thiolate complexes with halogenated compounds such as PhCH(2)Br, CH(3)I, CCl(4), and Ph(3)CCl have been examined and several mechanistic pathways have been explored.

Several linear molecules containing the C alpha, alpha-diphenylglycine residue were prepared as potential anticonvulsants. The conformational preferences of the C alpha, alpha-diphenylglycine residue were assessed in these synthetic derivatives and dipeptides by X-ray diffraction, FTIR absorption and 1H NMR techniques, and by conformational energy computations. Five (out of six) derivatives adopt the fully extended C5 conformation in the crystal state. This intramolecularly H-bonded form is largely populated in chloroform solution in all the derivatives investigated. Conformational energy computations in vacuo support the view that the intramolecularly H-bonded C7-ring form is the most stable structure for these compounds. Only one linear derivative exhibits a (modest) anticonvulsant activity.

The title compound, C13H19Cl2N2+·Cl−, exhibits stereochemical features that are deemed necessary for 5-HT1 subtype serotonin receptor interaction. A distance of 5.69 (1) A is observed between the protonated nitro­gen and the centroid of the phenyl ring. The piperazine ring adopts a chair conformation and the protonated nitro­gen is involved in hydrogen bonding to the chloride counter-ion. The chloro­phenyl moiety is disordered, with the major conformer adopting a trans, trans geometry while the minor conformer is trans, gauche.

The title compound, Ox3H3 or C9H18N4O3, adopts an open extended structure which does not restrict solvent accessibility or metallation reactivity. An intermolecular O—H⋯N hydrogen bond is observed.

The single-crystal X-ray diffraction study of the title mol­ecule, C21H19NS, confirms the twist–boat conformation of the thia­zepine ring. The two phenyl groups are equatorially oriented with respect to the thia­zepine ring.

The reactions of the title ylide with HgX2 (X = Cl, Br or I) lead to the regiospecific binding of the acetyl oxygen to soft Hg(II), producing a chloro complex with (2 + 2) coordination and isostructural dimeric bromo and iodo complexes containing halogen bridges with tetrahedral configurations around the metal centres.

The PF(6)(-) salt of a platinum(II) complex changes from yellow to red and becomes intensely luminescent upon exposure to aqueous ClO(4)(-). The response is remarkably selective. Spectroscopic changes are consistent with anion exchange resulting in shortening of the intramolecular PtPt distances between the square planar cations.

Tris­[2-(benzoyl­amino)­ethyl]­amine [alternatively, N,N′,N′′-(nitrilo­tri­ethyl)­tri­benz­amide], C27H30N4O3, adopts a folded structure, forming a symmetrical cavity with an average depth of 7.3 A and width ranging from 4.1–4.4 A. The folded structure is a result of one intramolecular N—H⋯O hydrogen bond. A linear chain motif along the c axis best describes the extended intermolecular N—H⋯O hydrogen bonding.

The title compound (C9H4Cl3NO2S), commonly known as Folpet, belongs to a group of phthalimides which function as fungicides or can be used in the laboratory as sulfurizing agents. The phthalimide moiety is slightly folded with a dihedral angle of 3.5 (4)°. The molecule participates in C—H⋯O and Cl⋯Cl intermolecular interactions.

The reaction between (μ-H) 2 Os 3 (CO) 10 and (η 5 -C 5 H 5 )Rh(CO) 2 in toluene at 90°C produces (η 5 -C 5 H 5 )RhOs 2 (CO) 9 (I) and (μ-H) 2 (η 5 -C 5 H 5 )RhOs 3 (CO) 10 (II), as the principal products while the pentanuclear cluster (μ-H) 2 (η 5 -C 5 H 5 )RhOs 4 (CO) 13 (III) is obtained in low yield. When added hydrogen is present during the reaction, replacement of the cyclopentadienide ligand by toluene occurs and the principal product is (μ-H) 3 (η 6 -C 6 H 5 CH 3 )RhOs 3 (CO) 9 (VI). Also produced in this reaction are (μ-H) 2 (η 5 -C 5 H 5 ) 2 Rh 2 Os 2 (CO) 7 (IV) and cluster II, but in low yields. In benzene in the presence of H 2 , an analogous reaction occurs. The cyclopentadienide ligand is replaced by benzene to give (μ-H) 3 (η 6 -C 6 H 6 )RhOs 3 (CO) 9 (VII) as the main product and clusters II and (μ-H) 4 (η 5 -C 5 H 5 )RhOs 3 (CO) 9 (V) are formed in small yields. Conversion of clusters I and II to clusters IV and V, respectively, was achieved by bubbling H 2 through toluene solutions of I and II at 90°C. Cluster V is moderately unstable in solution, with significant decomposition occurring during the reaction. The molecular structures of clusters II, III, IV, and VII have been determined by single crystal X-ray diffraction studies. Clusters II, IV, and VII have tetrahedral metal cores, while the pentanuclear cluster III has an Os tetrahedral core which is edge bridged by a Rh atom. For compound II: space group P 2 1 / n , a 8.120(3), b 14.932(3), c 16.277(3) A, β 91.29(4)°, V 1972.9 A 3 , Z = 4, mol wt = 1020.73, ρ calcd 3.434 gm cm −3 , and μ calcd 201.5 cm −1 for Mo- K α ; 3885 independent reflections ⩾ 3σ( I ); 4 ⩽ 2θ ⩽ 55° obtained at −35°C; final R f 5.7%, R wf 7.4%. For compound III: space group P 2 1 / c , a 11.134(2), b 16.649(2), c 14.015(2) A, β 109.98(1)°, V 2441.6 A 3 , Z = 4, mol wt = 1294.95, ρ calcd = 2.773 gm cm −3 , and μ calcd 162.6 cm −1 for Mo- K α ; 5695 independent reflections ⩾ 3σ( I ); 4 ⩽ 2θ ⩽ 50° at −30°C; final R f 2.95%, R wf 4.0%. For compound IV: space group P 2 1 / c , a 8.186(3), b 15.651(5), c 15.723(2) A, β 97.32°, V 1998.25 A 3 , Z = 4, mol wt = 914.49, ρ calcd 3.038 gm cm −3 , and μ calcd 143.34 cm −1 for Mo- K α ; 3619 independent reflections ⩾ 3σ( I ); 4 ⩽ 2θ ⩽ 55° at 25°C; final R f 3.3%, R wf 4.5%. For compound VII: space group R , a = b = c = 10.003(4) A, α = β = γ = 92.16(3)°, V = 998.3 A 3 , Z = 2, mol wt = 1006.5, ρ calcd 3.34 gm cm −3 , and μ calcd 214.8 cm −1 Mo- K α ; 3017 independent reflections ⩾ 3σ( I ); 4 ⩽ 2θ ⩽ 50° at 25°C; Final R f 4.4%, R wf 6.3%.