Treatment of the triangular [MoSCl(dbbpy)]Cl cluster ([1]Cl) with CuCl produces a novel tetrametallic cuboidal cluster [Mo(CuCl)SCl(dbbpy)][CuCl] ([2][CuCl]), whose crystal structure was determined by X-ray diffraction (dbbpy = 4,4'-di-tert-butyl-2,2'-bipyridine). This species, which contains two distinct types of Cu(I), is the first example of a diimine-functionalized heterometallic MM'S cluster. Kinetics studies on both the formation of the cubane from the parent trinuclear cluster and its dissociation after treatment with halides, supported by NMR, electrospray ionization mass spectrometry, cyclic voltammetry, and density functional theory calculations, are provided.
View Article and Find Full Text PDFA versatile photoreactor was built for studying homogeneous and heterogeneous photochemical reactions using fiber-optic devices. The reactor was designed to allow simultaneous photochemical initiation and online spectrophotometric monitoring of the reaction using independently controlled excitation and detection lamps. The system consists of a CCD spectrophotometer, a thermostated sample holder, two light sources, and standard 1.
View Article and Find Full Text PDFThe aminophosphine ligand (2-aminoethyl)diphenylphosphine (edpp) has been coordinated to the W3(μ-S)(μ-S)3 cluster unit to afford trimetallic complex [W3S4Br3(edpp)3](+) (1(+)) in a one-step synthesis process with high yields. Related [W3S4X3(edpp)3](+) clusters (X = F(-), Cl(-), NCS(-); 2(+)-4(+)) have been isolated by treating 1(+) with the corresponding halide or pseudohalide salt. The structure of complexes 1(+) to 4(+) contains an incomplete W3S4 cubane-type cluster unit, and only one of the possible isomers is formed: the one with the phosphorus atoms trans to the capping sulfur and the amino groups trans to the bridging sulphurs.
View Article and Find Full Text PDFA study, involving kinetic measurements on the stopped-flow and conventional UV/Vis timescales, ESI-MS, NMR spectroscopy and DFT calculations, has been carried out to understand the mechanism of the reaction of [Mo3 S4 (acac)3 (py)3 ][PF6 ] ([1]PF6 ; acac=acetylacetonate, py=pyridine) with two RCCR alkynes (R=CH2 OH (btd), COOH (adc)) in CH3 CN. Both reactions show polyphasic kinetics, but experimental and computational data indicate that alkyne activation occurs in a single kinetic step through a concerted mechanism similar to that of organic [3+2] cycloaddition reactions, in this case through the interaction with one Mo(μ-S)2 moiety of [1](+) . The rate of this step is three orders of magnitude faster for adc than that for btd, and the products initially formed evolve in subsequent steps into compounds that result from substitution of py ligands or from reorganization to give species with different structures.
View Article and Find Full Text PDFReaction of [Mo3(μ3-S)(μ-S)3] clusters with alkynes usually leads to formation of two C-S bonds between the alkyne and two of the bridging sulfides. The resulting compounds contain a bridging alkenedithiolate ligand, and the metal centers appear to play a passive role despite reactions at those sites being well illustrated for this kind of cluster. A detailed study including kinetic measurements and DFT calculations has been carried out to understand the mechanism of reaction of the [Mo3(μ3-S)(μ-S)3(H2O)9](4+) (1) cluster with two different alkynes, 2-butyne-1,4-diol and acetylenedicarboxylic acid.
View Article and Find Full Text PDFInorg Chem
August 2013
Water-soluble [M3S4X3(dhbupe)3](+) diphosphino complexes (dhbupe = 1,2-bis(bis(hydroxybutyl)phosphino)ethane), 1(+) (M = Mo, X = Cl) and 2(+) (M = W; X = Br), have been synthesized by extending the procedure used for the preparation of their hydroxypropyl analogues by reaction of the M3S4(PPh3)3X4(solvent)x molecular clusters with the corresponding 1,2-bis(bishydroxyalkyl)diphosphine. The solid state structure of the [M3S4X3(dhbupe)3](+) cation possesses a C3 symmetry with a cuboidal M3S4 unit, and the outer positions are occupied by one halogen and two phosphorus atoms of the diphosphine ligand. At a basic pH, the halide ligands are substituted by hydroxo groups to afford the corresponding [Mo3S4(OH)3(dhbupe)3](+) (1OH(+)) and [W3S4(OH)3(dhbupe)3](+) (2OH(+)) complexes.
View Article and Find Full Text PDFThe [Mo(3)S(4)Cl(3)(dhprpe)(3)](+) (1(+)) cluster cation has been prepared by reaction between Mo(3)S(4)Cl(4)(PPh(3))(3) (solvent)(2) and the water-soluble 1,2-bis(bis(hydroxypropyl)phosphino)ethane (dhprpe, L) ligand. The crystal structure of [1](2)[Mo(6)Cl(14)] has been determined by X-ray diffraction methods and shows the typical incomplete cuboidal structure with a capping and three bridging sulfides. The octahedral coordination around each metal center is completed with a chlorine and two phosphorus atoms of the diphosphine ligand.
View Article and Find Full Text PDFThe synthesis, crystal structure and solution characterization of the cubane-type [Mo(3)(FeCl)S(4)(dmpe)(3)Cl(3)] (1) (dmpe = 1,2-bis(dimethylphophane-ethane)) cluster are reported and the ligand substitution processes of chloride by thiophenolate investigated. The kinetics and the intimate mechanism of these substitutions reveal that compound 1 undergoes a number of Fe and Mo site specific ligand substitution reactions in acetonitrile solutions. In particular, PhS(-) coordination at the tetrahedral Fe site proceeds in a single resolved kinetic step whereas such substitutions at the Mo sites proceed more slowly.
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