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Dinuclear and Heteropolynuclear Complexes Containing Mo24+ Units

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posted on 22.01.2001, 00:00 by Rodolphe Clérac, F. Albert Cotton, Kim R. Dunbar, Carlos A. Murillo, Xiaoping Wang
The quadruply bonded compound Mo2(DpyF)4 (1), where DpyF- is the anion of N,N-di(2-pyridyl)formamidine, has been prepared by ligand substitution reactions of Mo2(OOCCF3)4 and either the neutral ligand, HDpyF, at ambient temperature or its lithium salt, LiDpyF, under refluxing conditions. An X-ray structural analysis shows that 1 has a paddlewheel structure with a MoMo distance of 2.1108(6) Å. Reaction of 1 with CoCl2 in methanol produces the paramagnetic compound [Mo2Co(DpyF)4][CoCl4]·2MeOH (2). The Co(II) atom in the cation [Mo2Co(DpyF)4]2+ resides on a low-spin hexacoordinate environment (S = 1/2) with a Co···Mo separation of 2.979(6) Å, suggesting there is no direct bonding interaction between the Co and Mo atoms. The Mo−Mo distance of 2.1096(5) Å is similar to that in 1. Reaction of 1 and CuCl in methanol yields [Mo2Cu4(DpyF)4Cl2][CuCl2]2·2MeOH·Et2O (3). In the cation there are two copper atoms on each side of the Mo2 core. Each is coordinated to two pyridyl nitrogen atoms of the cis DpyF- ligands and loosely bridged to the other by a chloride ion. As a result, the Cu(I) atoms are not aligned with the Mo2 unit. The Cu to Mo separations are in the range 3.003(1)−3.015(1) Å, and the Mo−Mo distance of 2.127(1) Å is comparable to those in 1 and 2.