Abstract
The preparation and characterization of a series of divalent 3d transition metal complexes supported by a tridentate planar bis(iminopyridine) ligand are reported. The complexes {2,6-[PhC=N(tBu(2)C(6)H(3))](2)C5H3N}MBr2 (M = Mn, Fe, Co, Ni, Cu, Zn), 1-6, were characterized by single crystal X-ray structural studies revealing complexes with pentacoordinate distorted square pyramidal coordination environments. This assembly of complexes provided a unique array for examining the relationship between experimental structure and computed electronic structure. While experimental structural features basically correlated with the Irving-Williams series, some clear deviations were rationalized through the computational analysis. A balance of bis(imino) pyridine/metal with bonding/antibonding pi interactions was used to explain the divergent directions of Fe(II)-N and Co(II)-N bond lengths. Similarly, orbital details were used to justify the opposing change in Cu-Br-ap and Cu-Br-bas bond lengths. Furthermore, computational analysis provided a unique method to document a surprising low bond order for the M-N bonds of bis(imino) pyridine ligand in this series.