Assessing the Metal–Metal Interactions in a Series of Heterobimetallic Nb/M Complexes (M = Fe, Co, Ni, Cu) and Their Effect on Multielectron Redox Properties
journal contributionposted on 20.12.2018 by Brett A. Barden, Gursu Culcu, Jeremy P. Krogman, Mark W. Bezpalko, Gregory P. Hatzis, Diane A. Dickie, Bruce M. Foxman, Christine M. Thomas
Any type of content formally published in an academic journal, usually following a peer-review process.
A one-pot synthetic procedure for a series of bimetallic Nb/M complexes, Cl–Nb(iPrNPPh2)3M–X (M = Fe (2), Ni (4), Cu (5)), is described. A similar procedure aimed at synthesizing a Nb/Co analogue instead affords iPrNNb(iPrNPPh2)2(μ-PPh2)Co–I (3) through cleavage of one phosphinoamide P–N bond under reducing conditions. Complexes 4 and 5 are found to have short Nb-M distances, corresponding to unusual metal–metal bonds between Nb and these first row transition metals. For comparison, a series of heterobimetallic ONb(iPrNPPh2)3M–X complexes (M = Fe (7), Co (8), Ni (9), Cu (10)) was synthesized. In these complexes, the NbV center is engaged in sufficient π-bonding to the terminal oxo ligand to remove the driving force for direct metal–metal interactions. A comparison of the cyclic voltammograms of 2 and 4–10 reveals that the presence of a second metal shifts the redox potentials of both Nb and the late metal center anodically, even when direct metal–metal interactions are not present.