Transition-metal nitrosyl compounds. Part X. A study of olefin rotation in [Os(CO)NO(C2H4)(PPh3)2][PF6]
Abstract
The reaction of [Os(CO)NO(PPh3)2Cl] first with silver hexafluorophosphate and then ethylene leads to formation of the PF6– salt of the cation [Os(CO)NO(C2H4)(PPh3)2]+. This cation is thought to possess a trigonal bipyramidal geometry in which the CO, NO, and C2H4 ligands occupy equatorial positions. Under ambient conditions the ethylene rotates and variable temperature 13C n.m.r. data provide direct experimental evidence that this type of rotation occurs via the metal–olefine bond. The value of ΔG‡Tcwas determined as 9.5 ± 0.2 kcal mol–1.