Aryldiazo complexes, [M(CO)2(NNPh)(PPh3)2] [PF6] (M = Os, Ru; Ph = C6H5), have been prepared by allowing diazonium salts to react with M(CO)3(PPh3)2. Infrared spectra of the Ru complex suggest the presence of two isomers both in solution and in the solid state. These complexes react with a variety of coordinating anions (X-), to form MX(CO)2(NNPh)(PPh3)2. The osmium derivatives have ν(NN) near 1455 cm-1, which is the lowest value yet reported for a nonbridging aryldiazo ligand. The first aryldiazo-hydrido complexes, MH(CO)2(NNPh)(PPh3)2 and MH(CO)(NNPh)(PPh3)2, were prepared by deprotonation of the respective phenyldiazene complexes, MH(CO)2(HNNPh)(PPh3)2+ and MH(CO)(HNNPh)(PPh3)3+. The compound OsCl3(NNPh)(PPh3)2 has also been prepared. A large number of the foregoing complexes have been synthesized with selective 2H and 15N labels. Infrared and NMR spectra show MX(CO)2(NNPh)(PPh3)2 and the analogous hydrido complex to be pseudooctahedral with trans phosphine ligands, cis carbonyl ligands, and a doubly bent phenyldiazenido (NNPh-) ligand. Similarly, MH(CO)(NNPh)(PPh3)2 possesses a trigonal-bipyramidal geometry with trans phosphine ligands and an equatorial, singly bent phenyldiazoniumato (NNPh+) ligand. Isotopic substitution of the diazo ligand shows that ν(NN) is often vibrationally coupled with phenyl vibrational modes and that two or three bands sometimes shift upon 15N substitution. Vibrational coupling is also observed in the higher energy region (1850-1900 cm-1) in the compound RuCl3(NNC6D5)(PPh3)2. The wide range in the values of ν(NN), RuCl3(NNPh)(PPh3)2(1882 cm-1), vs. RuCl(CO)2(NNPh)(PPh3)2 (1462 cm-1), indicates that the N-N stretching frequencies are sensitive to the electronic and steric environment of the diazo ligand. The aryldiazo complexes are compared with analogous, isoelectronic nitrosyl complexes of Os and Ru.
ASJC Scopus subject areas
- Physical and Theoretical Chemistry
- Inorganic Chemistry