Reactions of toluene-p-sulphonyl azide and isocyanate with low valent transition-metal complexes

Abstract

The reactions of toluene-p-sulphonyl azide (RN₃) with the complexes Pd(PPh₃)₃CO and M(NO)(CO)(PPh₃)₂(M = Rh or Ir) in benzene yield urea derivatives of the type Pd(PPh₃)₂(RNCONR) and M(NO)(PPh₃)₂(RNCONR)(R =p-CH₃C₆H₄SO₂). From Pt(PPh₃)_n(CO)_{4 –n}(n= 2 or 3) and RN₃ however a more complex compound (PPh₃)₂Pt(R₂N₄CO) is obtained, whilst the platinum ureylene complex Pt(PPh₃)₂(RNCONR) can be synthesized by oxidative addition of NN′-ditoluene-p-sulphonyl urea to Pt(PPh₃)₄. The urea complexes have also been prepared by treatment of M(PPh₃)₄(M = Pd or Pt) and M(NO)(PPh₃)₃(M = Rh or Ir) with toluene-p-sulphonyl isocyanate. Similarly RhCl(PPh₃)₂(RNCONR) has been isolated from the reactions of Rh(PPh₃)₃Cl with RNCO or RNHCONHR. In protic solvents such as alcohols R′OH (R′= Me, Et, or Prⁿ) the reactions of RN₃ with complexes Pt(PPh₃)_n(CO)_{4 –n}(n= 2 or 3) lead to different products, as expected. For n= 2, the bis-alkoxycarbonyl derivative trans-Pt(PPh₃)₂(CO₂R′)₂ has been isolated, whereas for n= 3, Pt(PPh₃)₂N₃(–[graphic omitted]–COOR′) is the main product. Treatment of the hydride complex RhH(Ph₂PCH₂CH₂PPh₂)₂ with toluene-p-sulphonyl azide gives a dimeric complex, probably with a di-imide bridge (Ph₂PCH₂CH₂PPh₂)₂Rh(RNNR)Rh(Ph₂PCH₂CH₂PPh₂)₂.