“…[50] Hey-Hawkins and co-workers reported that, in the absence of a stabilizing donor ligand, on dehydrohalogenation of tantalum-complexed primary phosphine [Cp*(Cl 4 )Ta(PH 2 À Is)], the 14-electron phosphinidene complex [Cp*(Cl 2 )Ta=PÀIs] (56, 31 P d = 488.0 ppm) was isolated; no mention was made of intermediate products. [51] Lammertsma and co-workers showed that dehydrohalogenation of primary phosphine complex 48 a with the strong phosphazene base tert-butylimino-tri(pyrrolidino)phosphorane (BTPP, pK b % 26) in the absence of a ligand gave 18-electron complex 57 and one-half equivalent of the dimer [{Cp*IrCl 2 } 2 ] (58, Scheme 17 a). [52] Phosphinidene 57 , as identified by its 31 P NMR spectrum (d = 366 and À126 ppm), and suggests that the first dehydrohalogenation is faster than the second one.…”