In Search of Fulminate Analogues: L 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) (Tp*)] (Tp*=hydrotris(dimethylpyrazolyl)borate) with nBuLi and ClP=NMes* (Mes*=C H tBu -2,4,6) afforded mixtures of the complexes [Mo(≡CPnBuNHMes*)(CO) (Tp*)] and traces of the bimetallic products [Mo {μ -C P O(NHMes) }(CO) (Tp*) ] and [Mo (μ -C PNHMes)(CO) (Tp*) ]. The reaction of [W(≡CBr)(CO) (Tp*)] with nBuLi and ClP=NMes* afforded predominantly the mononuclear carbyne [W{≡CP(=NMes*)nBu })(CO) (Tp*)] and traces of the binuclear complex [W (μ-C PNHMes)(CO) (Tp*) ] which is also obtained when tBuLi is used. Although not isolable, the intended complexes [M(≡CPNMes*)(CO) (Tp*)] could be generated in situ and spectroscopically characterized via the reactions of the stannyl carbynes [M(≡CSnnBu )(CO) (Tp*)] and ClP=NMes*. The preceding observations are mechanistically interpreted with reference to a computational interrogation of the model complex [Mo(≡CP=NCH )(CO) (Tp*)], the LUMO of which has considerable phosphorus character.