Synthesis and reactivity of an anionic allenylidene complex.

The reaction of [W([triple bond, length as m-dash]CC[triple bond, length as m-dash]CSiMe3)(CO)2(Tp*)] (Tp* = hydrotris(dimethylpyrazolyl)borate) with MeLi generates the first example of an anionic allenylidene complex Li[W([double bond, length as m-dash]C[double bond, length as m-dash]C[double bond, length as m-dash]CMeSiMe3)(CO)2(Tp*)] which reacts with electrophiles (H+, Me+) at the β-carbon to afford vinylcarbyne (allylidyne) complexes [W([triple bond, length as m-dash]CCE[double bond, length as m-dash]CMeSiMe3)(CO)2(Tp*)] (E = H, Me), and with bromine provides the unprecedented binuclear bis(carbyne) complex {C([double bond, length as m-dash]CMeSiMe3)C[triple bond, length as m-dash]W(CO)2(Tp*)}2via oxidative C-C coupling at the β-carbon.