Effect of free and chelating phosphine coordination environments on the NiS2P2 chromophore:: synthesis, NMR and other spectral studies.: Crystal and molecular structures of (N,N-dipropyldithiocarbamato)di(triphenylphosphine)nickel(II) perchlorate and (N,N-dipropyldithiocarbamato)1,2-bis((diphenylphosphino)ethane)nickel(II) tetraphenylborate

Planar [Ni(dnpdtc)(PPh3)(2)] ClO4 . PPh3 (1) and [Ni(dnpdtc)(dppe)]BPh4 . H2O (2) (dnpdtc = N,N-dipropyldithiocarbamate, dppe = 1,2-bis(diphenylphosphino)ethane) complexes were prepared and characterized by elemental analysis, electronic, IR and NMR spectra and their structures were determined by single crystal X-ray crystallography. Both the complexes were diamagnetic. IR spectra of the two compounds show isobidentate coordination of the dithiocarbamate moiety. The important stretching mode characteristic of the thioureide bond occurs at 1536 and 1526 cm(-1) for 1 and 2, respectively. The BVS data support the highly covalent nature of the Ni-S interaction. NMR spectra of the complexes show very large (similar to20 ppm) 31 p chemical shifts in both compounds. The most important N-13 CS2 chemical shifts appear at 199.17 and 201.88 ppm for 1 and 2, respectively. Structural implications are very large for 2 compared to 1 when free phosphines are replaced by chelating dppe with the P-Ni-P angle shrinking to approximately 12degrees. (C) 2003 Elsevier Ltd. All rights reserved.