title: Unique molecular geometries of reduced 4- and 5-coordinate zinc complexes stabilised by diiminopyridine ligand.
abstract: Stepwise reduction of the diiminopyridine (dimpyr) complex, dimpyrZnCl2, by KC8 leads to molecular zinc compounds dimpyrZnCl (2) and dimpyrZnCl(DMAP) (3, DMAP = 4-dimethylaminopyridine), which were characterized by X-ray diffraction and EPR spectroscopy. Compound 2 shows an unusual nearly square planar geometry of the zinc atom equally ligated by two imine groups. X-ray crystallographic and EPR data suggest significant delocalization of the zinc 4p electron onto the non-innocent dimpyr ligand. The chloride in 2 can also be substituted by a methyl group upon addition of methyl lithium to generate compound 4, dimpyrZnMe. The novel alkylzinc compound displayed approximate square planar geometry around the zinc centre and significant delocalization of electron density onto the dimpyr ligand, as revealed by X-ray crystallographic studies and EPR spectroscopy, akin to 2. Further reduction of 3 leads to compound 5, dimpyrZn(DMAP)2. X-ray diffraction study of 5 revealed an unprecedented see-saw geometry around the four-coordinate zinc center with significant electron density transfer to the dimpyr ligand, supported by DFT calculations.
authors.affiliation: Department of Chemistry, Brock University, 1812 Sir Isaac Brock Way, St Catharines, Ontario, Canada L2S 3A1. gnikonov@brocku.ca.
authors.forename: Terry
authors.initials: T
authors.lastname: Chu
authors.forename: Lee
authors.initials: L
authors.lastname: Belding
authors.forename: Prashanth K
authors.initials: PK
authors.lastname: Poddutoori
authors.forename: Art
authors.initials: A
authors.lastname: van der Est
authors.forename: Travis
authors.initials: T
authors.lastname: Dudding
authors.forename: Ilia
authors.initials: I
authors.lastname: Korobkov
authors.forename: Georgii I
authors.initials: GI
authors.lastname: Nikonov