Coordination of E‒C bonds (E = Zn, Mg, Al) and the Zn‒H Bonds of (C5Me5)ZnH and (C5Me5)ZnZnH across a Quadruply Bonded Dimolybdenum Dihydride Complex

Abstract

Heterobimetallic complexes containing M-C-E linkages (M = transition metal atom; E = main group metal) have been postulated as relevant intermediates in cross-coupling reactions. Despite this, structural data for these species are scarce. In this contribution, we explore the coordination of E-C bonds (E = Zn, Mg, Al) to the Mo atoms of dimolybdenum complexes containing quadruple Mo-Mo bonds. In addition, the reactivity of the bis(hydride) [Mo2(H)2(μ-AdDipp2)2(thf)2] complex (AdDipp2 = HC[N(2,6-iPr2C6H3)]2) with the zincocenes Zn(C5Me5)2 and Zn2(η5-C5Me5)2 reveals the formation of dimolybdenum compounds in which (C5Me5)Zn-H and (C5Me5)ZnZn-H bonds bind to the trans-H-Mo≣Mo-H core. DFT calculations and an NBO analysis disclose a general bonding mechanism for the reported H-Mo≣Mo-E-R rings that is consistent with the penetration indices of the different atom pairs. The bonding comprises three center-two electron Mo-H-E and Mo-R-E bonds supplemented by π-coordination of the Mo≣Mo bond to the electropositive metal E.