Construction of symmetric and asymmetric Mo/S/Cu clusters from a cluster precursor [Et4N]2[(edt)2Mo2S2(mu-S)2] (edt = ethanedithiolate).

Treatment of [Et 4N] 2[(edt) 2Mo 2S 2(mu-S) 2] ( 1) (edt = ethanedithiolate) with equimolar CuBr afforded an anionic hexanuclear cluster [Et 4N] 2[(edt) 2Mo 2(mu-S) 3(mu 3-S)Cu] 2.2CH 2Cl 2 ( 2.2CH 2Cl 2). 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) 2Mo 2O 2(mu-S) 2Cu 2(dppm) 2] ( 3) and [(edt) 2Mo 2O(mu 3-S)(mu-S) 2Cu 2(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) 2Mo 2(mu-S) 2(mu 3-S) 2Cu 2(dppm)(Py)].Py ( 5.Py). Compounds 2- 5 have been characterized by elemental analysis, UV-vis spectra, IR spectra, (1)H NMR, and X-ray analysis. The structure of the dianion of 2 can be viewed as having a [Mo 4S 8Cu 2] core in which two chemically equivalent [Mo 2(mu-S) 3(mu 3-S)(edt) 2Cu] (-) anions are linked by two extra Cu-S edt bonds. The molecular structure of 3 may be visualized as being built of one [(edt) 2Mo 2X 2(mu-S) 2] (2-) dianion and one [Cu 2(dppm) 2] (2+) dication that are connected by a pair of M-mu-S edt bonds. Compound 4 is formed by the affiliation of two Cu(I) atoms only at one end of the [(edt) 2Mo 2S 2(mu-S) 2] moiety, connecting with the S t atoms and the S edt atom. Cluster 5.Py can be viewed as being constructed from the addition of one Cu atom onto the incomplete cubanelike [Mo 2S 4Cu] 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.