Heterometallic Multiple Bonding: Delocalized Three-Center σ and π Bonding in Chains of 4d and 5d Transition Metals

摘要

Heterotrimetallic compounds Mo_2Ru-(dpa)_4Cl_2 (1) and W_2Ru(dpa)_4Cl_2 (2) are prepared by reactions of M_2(dpa)_4 (M = Mo or W; dpa = 2,2′-dipyridylamide) with [Ru(CO)_3Cl_2]_2. Crystallographic studies reveal short Mo-Ru and W-Ru distances, 2.38 ? (1) and 2.39 ? (2), suggestive of delocalized Mo-Mo-Ru and W-W-Ru bonding. In contrast to the σ bonding found in the corresponding iron compounds, density functional theory calculations reveal both a three-center/two-electron σ bond and two three-center/four-electron π bonds in the M-M-Ru compounds.