59802-90-3Relevant academic research and scientific papers
Linear Co-ordinative Bonding at Oxygen: A Spectroscopic and Structural Study of Phosphine Oxide-Group 13 Lewis Acid Adducts
Burford, Neil,Royan, Bruce W.,Spence, Rupert E. v. H.,Cameron, T. Stanley,Linden, Anthony,Rogers, Robin D.
, p. 1521 - 1528 (1990)
A number of adducts composed of phosphine oxides and Group 13 Lewis acids R3PO*EX3 (R = Ph, NMe2, or PhO; E = B, Al, or Ga; X = F, Cl, or Br) have been spectroscopically characterised by multinuclear n.m.r. spectroscopy.Three isostructural derivatives have been structurally characterised by X-ray crystallography.Crystal data (all hexagonal, space group 3, Z = 6): Ph3PO*AlCl3, a = 13.663(2), c = 18.258(2) Angstroem, R = 0.062; Ph3PO*AlBr3, a = 14.021(6), c = 18.387(3) Angstroem, R = 0.041; Ph3PO*GaCl3, a = 13.753(6), c = 18.345(6) Angstroem, R = 0.079.The structures show a uniquely linear or almost linear P-O-E backbone, which lies on the three-fold axis, in contrast to the bent structures observed for the corresponding BF3 adducts and other related systems.Short Al-O bonds are observed in both aluminium derivatives (E = Al).These compounds have narrow lines in the solution27Al n.m.r. spectra, indicative of a highly symmetric environment for the aluminium centre, and consistent with a linear geometry in solution.The results provide experimental evidence for axially symmetric dative bonding by oxygen, support the triple-bond model for the phosphine oxide unit, and imply the possibility of a delocalised ? interaction over the P-O-E framework.
