A T-Shaped Three-Coordinate Nickel(I) Carbonyl Complex and the Geometric Preferences of Three-Coordinate d<sup>9</sup> Complexes

A three-coordinate diketiminate-nickel(I) complex with a carbonyl ligand has been characterized using EPR and IR spectroscopies and X-ray crystallography. The T geometry (bending from the sterically favored <i>C</i><sub>2</sub><i><sub>v</sub></i> structure) contrasts with that of isosteric d<sup>9</sup> copper(II) complexes. DFT calculations on a truncated model reproduce experimental geometries, implying that the geometric differences are electronic in nature. Analysis of the charge distribution in the complexes shows that the geometry of the three-coordinate d<sup>9</sup> complexes is affected by differential charge donation of the ligands to the metal center.