Construction of Symmetric and Asymmetric Mo/S/Cu Clusters from a Cluster Precursor [Et<sub>4</sub>N]<sub>2</sub>[(edt)<sub>2</sub>Mo<sub>2</sub>S<sub>2</sub>(μ-S)<sub>2</sub>] (edt = Ethanedithiolate)
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Treatment of [Et4N]2[(edt)2Mo2S2(μ-S)2] (1) (edt = ethanedithiolate) with equimolar CuBr afforded an anionic hexanuclear cluster [Et4N]2[(edt)2Mo2(μ-S)3(μ3-S)Cu]2·2CH2Cl2 (2·2CH2Cl2). On the other hand, reactions of 1 with 2 equiv of CuBr in the presence of 1,2-bis(diphenylphosphino)methane (dppm) and pyridine (Py) ligands gave rise to two neutral tetranuclear clusters [(edt)2Mo2O2(μ-S)2Cu2(dppm)2] (3) and [(edt)2Mo2O(μ3-S)(μ-S)2Cu2(Py)4] (4), respectively. The reaction of 1 with 2 equiv of CuBr followed by the addition of a mixture of dppm and Py (molar ratio = 1:2) yielded another neutral tetranuclear cluster [(edt)2Mo2(μ-S)2(μ3-S)2Cu2(dppm)(Py)]·Py (5·Py). Compounds 2−5 have been characterized by elemental analysis, UV−vis spectra, IR spectra, 1H NMR, and X-ray analysis. The structure of the dianion of 2 can be viewed as having a [Mo4S8Cu2] core in which two chemically equivalent [Mo2(μ-S)3(μ3-S)(edt)2Cu]− anions are linked by two extra Cu−Sedt bonds. The molecular structure of 3 may be visualized as being built of one [(edt)2Mo2X2(μ-S)2]2− dianion and one [Cu2(dppm)2]2+ dication that are connected by a pair of M−μ-Sedt bonds. Compound 4 is formed by the affiliation of two Cu(I) atoms only at one end of the [(edt)2Mo2S2(μ-S)2] moiety, connecting with the St atoms and the Sedt atom. Cluster 5·Py can be viewed as being constructed from the addition of one Cu atom onto the incomplete cubanelike [Mo2S4Cu] framework through one terminal sulfur and one edt sulfur. Among the four clusters, 3 and 4 have internal mirror symmetry or pseudo mirror symmetry, respectively, while 2 and 5 are asymmetric clusters with racemic formation.
