摘要:
Reaction of Mo(CO)(6) with excess N,N'-di(3-methoxyphenyl)formamidine (HDmAniF) in o-dichlorobenzene afforded the yellow complex Mo-2(DmAniF)(4), 1. The structure of 1 reveals that the ligands bridge the two metal centers through the two nitrogen atoms, forming two s-cis, s-trans and two s-trans, s-trans conformations. Reaction of 1 with Me3OBF4 in CH3CN gave cis-[Mo-2(DmA-niF)(2)(CH3CN)(4)][BF4](2), 2, which crystallized in two different forms. The first form, 2 center dot CH2Cl2 center dot CH3CN, 2a, showing one BF4- anion coordinating to the axial positions of the Mo-Mo bond [Mo center dot center dot center dot F = 2.685(4) angstrom], contains two cis DmAniF(-) ligands which adopt the same s-cis, s-trans conformation. The other form, 2 center dot 0.5CH(2)Cl(2)center dot 0.5CH(3)CN, 2b, involves two independent molecules. While one [Mo-Mo = 2.1432(8) angstrom] of the two molecules shows axial interaction by CH3CN [Mo center dot center dot center dot N = 2.692(8) angstrom] and the two cis DmAniF(-) ligands adopt the same s-cis, s-trans conformation, the other one [Mo-Mo = 2.1317(9) angstrom] shows no axial interaction and the two cis DmAniF(-) ligands adopt different conformations, which are s-cis, s-trans and s-cis, s-cis, respectively. The Mo-Mo distance of 2a, 2.1281(6) angstrom, is the shortest among the compounds having Mo-2(mu(2)-L)(2)(CH3CN)(4) core, where L is the anionic, cationic or neutral form of a formamidine ligand. Reaction of 2 with NaOCH3 in CH3OH produced the tetranuclear complex cis-(Mo-2(DmAniF)(2)](2)(mu-OCH3)(4), 3. The molecule of 3 bears four bridging CH3O- groups that link two quadruply bonded moieties and the ligands adopts the s-trans, s-trans conformation. (C) 2008 Published by Elsevier B.V.