Phosphite and phosphonate complexes. Part II. Nuclear magnetic resonance spectra of triphenyl phosphite and dialkyl and diphenyl phosphonate complexes of rhodium, palladium, and platinum. An order of trans-influence for ligands in platinum(II) complexes

The parameters from the 31P n.m.r. spectra are reported for the complexes described in the precending paper and for some new complexes of platinum(II) and rhodium(III) which contain both tributylphosphine and triphenyl phos-phite. The coupling constants are examined in terms of an expression derived from the Fermi contact interaction and trends in the phosphrous chemical shifts are noted. The effects of anionic ligands coupling constants are shown to be similar in complexes where they are trans to (PhO)2PO–, Me–, and H–, These results are combined with coupling constants measured previously to derive and order of trans-influence on platinum-phosphrous bonds for uncharged and anionic ligands. It is shown that the ligand NO2 in trans-[PtH(NO2)(Et3P)2] is bonded to platinum through nitrogen in solution and not through oxygen as previously thought.