In Search of Fulminate Analogues: L n M≡CP=NR

The “CPNR” ligand may be viewed as being isolobal with fulminate, CNO; however, attempts to prepare a complex of such a ligand resulted instead in a range of novel imino and aminophosphinocarbyne complexes. Sequential treatment of [Mo(≡CBr)(CO) 2 (Tp*)] (Tp*=hydrotris(dimethylpyrazolyl)borate) with n BuLi and ClP=NMes* (Mes*=C 6 H 2 t Bu 3 ‐2,4,6) afforded mixtures of the complexes [Mo(≡CP n BuNHMes*)(CO) 2 (Tp*)] and traces of the bimetallic products [Mo 2 {μ 2 ‐C 2 P 2 O(NHMes) 2 }(CO) 4 (Tp*) 2 ] and [Mo 2 (μ 2 ‐C 2 PNHMes)(CO) 4 (Tp*) 2 ]. The reaction of [W(≡CBr)(CO) 2 (Tp*)] with n BuLi and ClP=NMes* afforded predominantly the mononuclear carbyne [W{≡CP(=NMes*) n Bu 2 })(CO) 2 (Tp*)] and traces of the binuclear complex [W 2 (μ‐C 2 PNHMes)(CO) 4 (Tp*) 2 ] which is also obtained when t BuLi is used. Although not isolable, the intended complexes [M(≡CPNMes*)(CO) 2 (Tp*)] could be generated in situ and spectroscopically characterized via the reactions of the stannyl carbynes [M(≡CSn n Bu 3 )(CO) 2 (Tp*)] and ClP=NMes*. The preceding observations are mechanistically interpreted with reference to a computational interrogation of the model complex [Mo(≡CP=NCH 3 )(CO) 2 (Tp*)], the LUMO of which has considerable phosphorus character.