Metal−Metal Multiple Bonds in Early/Late Heterobimetallics Support Unusual Trigonal Monopyramidal Geometries at both Zr and Co

摘要

The highly polarized metal-metal bonds in early/late heterobimetallicncomplexes present a unique strategy for tuning redoxnpotentials and small molecule activation processes.1 For example,nCasey and co-workers targeted early/late heterobimetallic dihydridesnfeaturing a hydridic early metal hydride and an acidic late metalnhydride as potential small molecule reducing agents.2 While annumber of early/late heterobimetallic complexes have been reported,nthere are few accounts of reactivity in which both metals areninvolved3 and limited reports of metal-metal multiple bondsnbetween early and late transition metals.4,5 Wolczanski and coworkersnreported several alkoxyphosphine-linked heterobimetallicncomplexes, namely Ti(OCMe2CH2PPh2)3Rh and Cp*Zr(OCH2-nPPh2)2RhMe2, featuring triple and double M-Rh bonds, respectively.n4 In light of this, our group has chosen to incorporate morenreactive first row transition metals into new early/late heterobimetallicncomplexes. Herein, we report the synthesis of Co/Zr heterobimetallicncomplexes featuring Co-Zr multiple bonds and thenability of these metal-metal interactions to support coordinativelynunsaturated species, including an unprecedented trigonal monopyramidalnZr complex.