A 31P and 199Hg nuclear magnetic resonance and vibrational spectroscopic study of triarylphosphine complexes of HgCl2

Complexes of the type [HgCl 2 P(4-XC 6 H 4 ) 3 ] 2 and HgCl 2 (P(4-XC 6 H 4 ) 3 ) 2 (X = Me 2 N, MeO, Me, H, F, Cl) have been prepared. The tertiary phosphines have similar steric requirements but vary greatly in their basicities. The vibrational spectra of the complexes were measured and each complex was found to have the expected bridging dimeric (1:1) or pseudotetrahedral monomeric (1:2 Hg/P) structure. Their 31 P and 199 Hg nmr parameters were investigated and it was found that 1 J(Hg—P) increases with increasing phosphine basicity, decreasing temperature, and decreasing sample concentration in dichloromethane solution. It is concluded that changes in the hybridisation on the P and Hg atoms may be largely responsible for the increases of 1 J(Hg—P) with increasing phosphine basicity.