Metal complexes of N-aryl-N-nitrosohydroxylamines: cleavage of N–N bonds to give metal nitrosyl species and organonitrogen compounds, and the crystal structure of [RhCl2{ONN(C6H4Me-p)O}(H2O)(PPh3)]·0.5Me2CO

Abstract

Reaction of [RhCl(PPh₃)₃], [Rh₂(CO)₄Cl₂], [Rh₂(η-C₅Me₅)₂Cl₄], [RuCl₂(PPh₃)₃], and [Pd(Ph)Cl(PPh₃)₂] with Q[ONN(R)O](Q = NH₄ or Ag; R = Ph or C₆H₄Me-p) afforded [RhL₂{ONN(R)O}](L = PPh₃ or CO), [Rh(η-C₅Me₅)Cl{ONN(R)O}], [Ru{ONN(R)O}₂(PPh₃)₂], and [PdPh{ONN(R)O}(PPh₃)]. Reaction of [Rh{ONN(R)O}(PPh₃)₂] with I₂ gave [{Rhl_x[ONN(R)O](PPh₃)₂}_n](R = Ph, x= 2, n= 1; R = C₆H₄Me-p, x= 1, n= unknown), and with CO gave [Rh(CO){ONN(R)O}(PPh₃)]. The latter was also prepared from [Rh(CO)₂{ONN(R)O}] and PPh₃. Treatment of [Rh{ONN(R)O}(PPh₃)₂] and [Ru{ONN(R)O}₂(PPh₃)₂] with RhCl₃ and RuCl₃ afforded [RhCl₂{ONN(R)O}(H₂O)(PPh₃)] and [RuCl{ONN(R)O}₂(PPh₃)₂], respectively. The structure of [RhCl₂{ONN(C₆H₄Me-p)O}(H₂O)(PPh₃)]·0.5Me₂CO was determined crystallographically, and the metal shown to be six-co-ordinate with a chelating N-aryl-N-nitrosohydroxylminato ligand and water. Treatment of [PdPh{ONN(R)O}(PPh₃)], [Rh{ONN(C₆H₄Me-p)O}(PPh₃)₂], and [Ru{ONN(C₆H₄Me-p)O}₂(PPh₃)₂] with HCl gave [Pd₂Cl₄(PPh₃)₂], [RhCl₂(NO)(PPh₃)₂], and [RuCl₃(NO)(PPh₃)₂], respectively, and the organic products obtained from the complexes of Rh and Ru identified by gas chromatography and mass spectrometry as p-MeC₆H₄NO, p-MeC₆H₄NH₂(major component), and C₆H₃Me(NH₂)Cl. A possible mechanism of formation of the nitrosyl complexes and organonitrogen compounds is briefly discussed.