Covalent alternatives for the elusive iminophosphonium cation. Crystal structures of PCl(NPri2)2NPh·AlCl3and P(NPri2)2[NPh(SO2CF3)]O
摘要:
Reactions between diaminoiminophosphinic chlorides and the chloride-abstracting agents AlCl3 and Ag(SO3CF3) have been comprehensively examined as potential routes to the three-co-ordinate iminophosphonium cation. However, bis(dialkylamino)(phenylimino)phosphinic chlorides react to give the covalent phosphoryl systems PCl(NR2)2NPh.AlCl3 and P(NR2)2[NPh(SO2CF3)]O respectively, in quantitative yield. The AlCl3 complexes are also prepared quantitatively from the reaction of P(NPr(i)2)2+AlCl4- with PhN3 (Staudinger reaction). All compounds have been comprehensively characterised and the structures of the isopropyl derivatives confirmed by X-ray crystallography. Crystal data: PCl(NPr(i)2)2NPh.AlCl3, space group P2(1), a = 8.719(2), b = 15.553(2), c = 9.509(2) angstrom, beta = 102.73(2)-degrees, Z = 2, R = 0.029; P(NPr(i)2)2[NPh(SO2CF3)]O, space group P2(1)/n, a = 10.594(3), b = 13.222(2), c = 17.084(3) angstrom, beta = 97.71(2)-degrees, Z = 4, R = 0.048. The results indicate that the three-co-ordinate diaminoiminophosphonium cation is thermodynamically unstable with respect to the observed alternative covalent structures, and that steric shielding is responsible for the stability of the analogous diaminomethylenephosphonium cation.
Covalent alternatives for the elusive iminophosphonium cation. Crystal structures of PCl(NPri2)2NPh·AlCl3and P(NPri2)2[NPh(SO2CF3)]O
摘要:
Reactions between diaminoiminophosphinic chlorides and the chloride-abstracting agents AlCl3 and Ag(SO3CF3) have been comprehensively examined as potential routes to the three-co-ordinate iminophosphonium cation. However, bis(dialkylamino)(phenylimino)phosphinic chlorides react to give the covalent phosphoryl systems PCl(NR2)2NPh.AlCl3 and P(NR2)2[NPh(SO2CF3)]O respectively, in quantitative yield. The AlCl3 complexes are also prepared quantitatively from the reaction of P(NPr(i)2)2+AlCl4- with PhN3 (Staudinger reaction). All compounds have been comprehensively characterised and the structures of the isopropyl derivatives confirmed by X-ray crystallography. Crystal data: PCl(NPr(i)2)2NPh.AlCl3, space group P2(1), a = 8.719(2), b = 15.553(2), c = 9.509(2) angstrom, beta = 102.73(2)-degrees, Z = 2, R = 0.029; P(NPr(i)2)2[NPh(SO2CF3)]O, space group P2(1)/n, a = 10.594(3), b = 13.222(2), c = 17.084(3) angstrom, beta = 97.71(2)-degrees, Z = 4, R = 0.048. The results indicate that the three-co-ordinate diaminoiminophosphonium cation is thermodynamically unstable with respect to the observed alternative covalent structures, and that steric shielding is responsible for the stability of the analogous diaminomethylenephosphonium cation.