Synthesis and structural characterization of [BseMe]Ni(PPh3)(NO), a nickel complex with a bent nitrosyl ligand

The nickel nitrosyl compound [Bse(Me)]Ni(PPh3)(NO) has been synthesized by the reaction of Ni(PPh3)(2)(NO)Br with potassium bis(2-seleno-1-methylimidazolyl)hydroborate, [Bse(Me)]K. X-ray diffraction studies demonstrate that (i) the B-H group of the [Bse(Me)] ligand interacts with the nickel center and (ii) the nitrosyl ligand is bent, with Ni-N-O bond angles of 149.1(3)degrees and 153.1(3)degrees for the two crystallographically independent molecules. The bent nature of the nitrosyl ligand in [Bse(Me)]Ni(PPh3)(NO) is in marked contrast to the linearity observed for the tris(2-seleno-1-mesitylimidazolyl)hydroborato counterpart [Tse(Mes)]NiNO (180.0 degrees). Density functional theory geometry optimization calculations demonstrate that the Ni center dot center dot center dot H-B interaction is not responsible for causing the nitrosyl ligand to bend, but rather the difference between [Tse(Mes)]NiNO and [Bse(Me)]Ni(PPh3)(NO) is due to the [Tse(Mes)] ligand allowing the former molecule to adopt a structure with C-3 symmetry. In contrast, the steric and electronic asymmetry of [Se2P] donor array of the [Bse(Me)] and PPh3 ligand combination prevents [Bse(Me)]Ni(PPh3)(NO) from having C-3 symmetry and the nitrosyl ligand bends to stabilize the occupied M-N sigma* antibonding orbital. (c) 2007 Elsevier Ltd. All rights reserved.