In Search of Fulminate Analogues: LnM≡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(equivalent to CBr)(CO)(2)(Tp*)] (Tp*=hydrotris(dimethylpyrazolyl)borate) withnBuLi and ClP=NMes* (Mes*=C(6)H(2)tBu(3)-2,4,6) afforded mixtures of the complexes [Mo(equivalent to CPnBuNHMes*)(CO)(2)(Tp*)] and traces of the bimetallic products [Mo-2{mu(2)-C2P2O(NHMes)(2)}(CO)(4)(Tp*)(2)] and [Mo-2(mu(2)-C(2)PNHMes)(CO)(4)(Tp*)(2)]. The reaction of [W(equivalent to CBr)(CO)(2)(Tp*)] withnBuLi and ClP=NMes* afforded predominantly the mononuclear carbyne [W{equivalent to CP(=NMes*)nBu(2)})(CO)(2)(Tp*)] and traces of the binuclear complex [W-2(mu-C(2)PNHMes)(CO)(4)(Tp*)(2)] which is also obtained whentBuLi is used. Although not isolable, the intended complexes [M(equivalent to CPNMes*)(CO)(2)(Tp*)] could be generated in situ and spectroscopically characterized via the reactions of the stannyl carbynes [M(equivalent to CSnnBu(3))(CO)(2)(Tp*)] and ClP=NMes*. The preceding observations are mechanistically interpreted with reference to a computational interrogation of the model complex [Mo(equivalent to CP=NCH3)(CO)(2)(Tp*)], the LUMO of which has considerable phosphorus character.