Decarbonylation reactions of formic acid by Group VIII halide complexes have been used to prepare new halogenocarbonyl complexes of the form cis-[M(CO)2X4]2– and cis-[M(CO)3X3]–(M = Os or Ru; X = Cl, Br, or l), [Os(CO)X5]3– and [M(CO)3X2]2(M = Os or Ru; X = Cl or Br), [M(CO)X5]2–(M = lr, Rh, or Ru; X = Cl or Br), and [Pt(CO)X3]–(X = Cl or Br). A number of triphenylphosphine derivatives of these products were also made, e.g. M(CO)2X2(PPh3)2(M = Os or Ru; X = Cl or Br). The vibrational spectra of the halogenocarbonyls were measured and assignments of fundamental modes proposed. The spectra of pentahalogeno-carbonyl and -nitrosyl species were compared and 13C and 15N substitution used to confirm the assignments.
