Coordination of 1-methyl-1,3-dihydro-2-benzimidazole-2-selone to zinc and cadmium: Monotonic and non-monotonic bond length variations for [H(sebenzim)]MCl complexes (M = Zn, Cd, Hg).

The reactions of 1-methyl-1,3-dihydro-2-benzimidazole-2-selone, H(sebenzim), towards the zinc and cadmium halides, MX (M = Zn, Cd; X = Cl, Br, I), afford the adducts, [H(sebenzim)]MX, which have been structurally characterized by X-ray diffraction. The halide ligands of each of these complexes participate in hydrogen bonding interactions with the imidazole N-H moieties, although the nature of the interactions depends on the halide. Specifically, the chloride and bromide derivatives, [H(sebenzim)]ZnX and [H(sebenzim)]CdX (X = Cl, Br), exhibit two intramolecular N-H•••X interactions, whereas the iodide derivatives, [H(sebenzim)]ZnI and [H(sebenzim)]CdI, exhibit only one intramolecular N-H•••I interaction.

Reactivity of the carbodiphosphorane, (PhP)C, towards main group metal alkyl compounds: coordination and cyclometalation.

The carbodiphosphorane, (Ph3P)2C, reacts with Me3Al and Me3Ga to afford the adducts, [(Ph3P)2C]AlMe3 and [(Ph3P)2C]GaMe3, which have been structurally characterized by X-ray diffraction. (Ph3P)2C also reacts with Me2Zn and Me2Cd to generate an adduct but the formation is reversible on the NMR time scale. At elevated temperatures, however, elimination of methane and cyclometalation occurs to afford [κ2-Ph3PC{PPh2(C6H4)}]ZnMe and [κ2-Ph3PC{PPh2(C6H4)}]CdMe.

Zerovalent Nickel Compounds Supported by 1,2-Bis(diphenylphosphino)benzene: Synthesis, Structures, and Catalytic Properties.

Zerovalent nickel compounds which feature 1,2-bis(diphenylphosphino)benzene (dppbz) were obtained via the reactivity of dppbz towards Ni(PMe), which affords sequentially (dppbz)Ni(PMe) and Ni(dppbz). Furthermore, the carbonyl derivatives (dppbz)Ni(PMe)(CO) and (dppbz)Ni(CO) may be obtained via the reaction of CO with (dppbz)Ni(PMe). Other methods for the synthesis of these carbonyl compounds include (i) the formation of (dppbz)Ni(CO) by the reaction of Ni(PPh)(CO) with dppbz and (ii) the formation of (dppbz)Ni(PMe)(CO) by the reaction of (dppbz)Ni(CO) with PMe.

Flexibility of the Carbodiphosphorane, (PhP)C: Structural Characterization of a Linear Form.

X-ray diffraction studies demonstrate that crystals of the carbodiphosphorane, (PhP)C, obtained from solutions in benzene, exhibit a linear P-C-P interaction. This observation is in contrast to the highly bent structures that have been previously reported for this molecule, thereby providing experimental evidence that the coordination geometry at zerovalent carbon may be very flexible. Density functional theory calculations support the experimental observations by demonstrating that the energy of (PhP)C varies relatively little over the range 130-180°.

Tris(2-mercaptoimidazolyl)hydroborato Cadmium Thiolate Complexes, [Tm]CdSAr: Thiolate Exchange at Cadmium in a Sulfur-Rich Coordination Environment.

A series of cadmium thiolate compounds that feature a sulfur-rich coordination environment, namely [Tm]CdSAr, have been synthesized by the reactions of [Tm]CdMe with ArSH (Ar = CH-4-F, CH-4-Bu, CH-4-OMe, and CH-3-OMe). In addition, the pyridine-2-thiolate and pyridine-2-selenolate derivatives, [Tm]CdSPy and [Tm]CdSePy have been obtained via the respective reactions of [Tm]CdMe with pyridine-2-thione and pyridine-2-selone. The molecular structures of [Tm]CdSAr and [Tm]CdEPy (E = S or Se) have been determined by X-ray diffraction and demonstrate that, in each case, the [CdS] motif is distorted tetrahedral and approaches a trigonal monopyramidal geometry in which the thiolate ligand adopts an equatorial position; [Tm]CdSPy and [Tm]CdSePy, however, exhibit an additional long-range interaction with the pyridyl nitrogen atoms.

Crystal structure of di-μ-chlorido-bis-[chlorido-bis-(1,2-dimethyl-5-nitro-1-imidazole-κ)copper(II)] acetonitrile disolvate.

1,2-Dimethyl-5-nitro-imidazole (dimetridazole, dimet) is a compound that belongs to a class of nitro-imidazole drugs that are effective at inhibiting the activity of certain parasites and bacteria. However, there are few reports that describe structures of compounds that feature metals complexed by dimet. Therefore, we report here that dimet reacts with CuCl·HO to yield a chloride-bridged copper(II) dimer, [CuCl(CHNO)] or [Cu(μ-Cl)Cl(dimet)].

Synthesis, structure and reactivity of [Tm(Bu(t))]ZnH, a monomeric terminal zinc hydride compound in a sulfur-rich coordination environment: access to a heterobimetallic compound.

The first terminal zinc hydride complex that features a sulfur-rich coordination environment, namely the tris(2-mercapto-1-tert-butylimidazolyl)hydroborato compound, [Tm(Bu(t))]ZnH, has been synthesized via the reaction of [Tm(Bu(t))]ZnOPh with PhSiH3. The Zn-H bond of [Tm(Bu(t))]ZnH is subject to insertion of CO2 and facile protolytic cleavage, of which the latter provides access to heterobimetallic [Tm(Bu(t))]ZnMo(CO)3Cp.

Phenylselenolate Mercury Alkyl Compounds, PhSeHgMe and PhSeHgEt: Molecular Structures, Protolytic Hg-C Bond Cleavage and Phenylselenolate Exchange.

The phenylselenolate mercury alkyl compounds, PhSeHgMe and PhSeHgEt, have been structurally characterized by X-ray diffraction, thereby demonstrating that both compounds are monomeric with approximately linear coordination geometries; the mercury centers do, nevertheless, exhibit secondary Hg•••Se intermolecular interactions that serve to increase the coordination number in the solid state. The ethyl derivative, PhSeHgEt, undergoes facile protolytic cleavage of the Hg-C bond to release ethane at room temperature, whereas PhSeHgMe exhibits little reactivity under similar conditions. Interestingly, the cleavage of the Hg-C bond of PhSeHgEt is also more facile than that of the thiolate analogue, PhSHgEt, which demonstrates that coordination by selenium promotes protolytic cleavage of the mercury-carbon bond.

Crystal structure of metronidazolium tetra-chlorido-aurate(III).

Metronidazole (MET) [systematic names: 1-(2-hy-droxy-eth-yl)-2-methyl-5-nitro-1H-imidazole and 2-(2-methyl-5-nitro-1H-imidazol-1-yl)ethanol] is a medication that is used to treat infections from a variety of anaerobic organisms. As with other imidazole derivatives, metronidazole is also susceptible to protonation. However, there are few reports of the structures of metronidazolium derivatives.

Exchange of Alkyl and Tris(2-mercapto-1--butylimidazolyl)hydroborato Ligands Between Zinc, Cadmium and Mercury.

The (2-mercaptoimidazolyl)hydroborato ligand, [Tm ], has been used to investigate the exchange of alkyl and sulfur donor ligands between the Group 12 metals, Zn, Cd and Hg. For example, [Tm ]Zn reacts with MeZn to yield [Tm ]ZnMe, while [Tm ]CdMe is obtained readily upon reaction of [Tm ]Cd with MeCd. Ligand exchange is also observed between different metal centers.

Synthesis and structures of cadmium carboxylate and thiocarboxylate compounds with a sulfur-rich coordination environment: carboxylate exchange kinetics involving tris(2-mercapto-1-t-butylimidazolyl)hydroborato cadmium complexes, [Tm(Bu(t))]Cd(O2CR).

A series of cadmium carboxylate compounds in a sulfur-rich environment provided by the tris(2-tert-butylmercaptoimidazolyl)hydroborato ligand, namely, [Tm(Bu(t))]CdO2CR, has been synthesized via the reactions of the cadmium methyl derivative [Tm(Bu(t))]CdMe with RCO2H. Such compounds mimic aspects of cadmium-substituted zinc enzymes and also the surface atoms of cadmium chalcogenide crystals, and have therefore been employed to model relevant ligand exchange processes. Significantly, both (1)H and (19)F NMR spectroscopy demonstrate that the exchange of carboxylate groups between [Tm(Bu(t))]Cd(κ(2)-O2CR) and the carboxylic acid RCO2H is facile on the NMR time scale, even at low temperature.