Structural effects of the chelating rings in trans-[Ni{Ph2P(Se)NPPh2-Se,P}2] and trans-[Ni{Ph2P(Se)NPPh2-Se,P}{Ph2P(Se)N(H)PPh2-Se,P}]Cl·CH2Cl2·H2O complexes
作者:Nikolaos Levesanos、Ioannis Stamatopoulos、Catherine P. Raptopoulou、Vassilis Psycharis、Panayotis Kyritsis
DOI:10.1016/j.poly.2009.05.006
日期:2009.10
The reaction of the monooxidised imidodiphosphinate ligand Ph2P(Se)NHPPh2 with NiCl2 center dot 6H(2)O in the presence of (BuOK)-Bu-t afforded [NiPh2P(Se)NPPh2-Se,P}(2)] (1), which was characterized by UV-Vis, IR and NMR spectroscopies. X-ray crystallographic studies on a single crystal of I revealed the trans Ni(Se,P)(2) arrangement in the solid state, showing a bis-chelating type of coordination. The diamagnetic P-31 NMR peaks of 1 in CDCl3 were interpreted as "deceptive" triplets, due to the conservation of the square-planar trans-isomer of I in solution. The structure of I exhibits a center of symmetry, with the two five-membered Ni-Se-P-N-P rings being equivalent. The higher electronegativity of Se compared to P is considered as the likely cause of the P-N bond length differences observed in the chelating rings of 1. During the reaction between NiCl2 center dot 6H(2)O and the ligand Ph2P(Se)N(S)-CH(CH3)Ph}PPh2, single crystals were obtained, the analysis of which by X-ray crystallography showed the formation of trans-[NiPh2P (Se)NPPh2-Se,P}Ph2P(Se)N(H)PPh2-Se,P}]Cl center dot CH2Cl2 center dot H2O (2). Complex 2 contains one Ni-Se-P-N(H)-P and one Ni-Se-P-N-P ring. Structural comparison between I and 2 makes possible to establish structural effects due to the protonation/deprotonation of the rings at their N atom. (C) 2009 Elsevier Ltd. All rights reserved.