96427-70-2Relevant academic research and scientific papers
Pentacarbonylvanadates(I-) containing C, N, and group 16 ligands. The relation between IR and 51V NMR shift parameters
Ihmels, Klaus,Rehder, Dieter
, p. 1340 - 1347 (2008/10/08)
The complexes [Et4N][V(CO)5L] with L = CNR, CN-, NCR, NR3, pyridines S(O)R2, OCMe2, SO2, and ER2 (E = O, S, Se, Te) have been prepared by ligand exchange from [V(CO)5THF]- or [V(CO)5Me2SO]- or by UV irradiation of [V(CO)6]- in THF in the presence of L at 195 K. As shown by 51V NMR, substituted pyridines NC5H4R exhibit an ambidentate coordination behavior, ligating via the pyridine N (R = H, 4-CN), NH2 (R = 2-NH2), or the nitrile N (R = 2-CN). 51V chemical shifts δ(51V) relative to VOCl3 span the range of -1339 (L = OPh2) to -1906 ppm (CNCH2CO2Et). Shielding increases as the ligand strength (mainly the π acceptor ability) and the ligand polarizability increase. IR spectroscopic π parameters relative to NEt3 vary from 173 (SO2) to -7 (NHEt2) and σ parameters from -75 (CNCH2CO2Et) to 21 Nm-1 (SPh2). Including data for L = PR3, N2, SnPh3-, and others, a linear correlation (coefficient 0.95) is obtained for δ(51V) vs χ/(6.5 + (π - σ), where χ is the electronegativity of the coordinating ligand function, (π - σ) a measure for the integral ligand strength, and 6.5 an empirical factor.
