Synthetic Routes to Transition‐Metal‐Substituted Pentadiynylidene Complexes

Sequential reaction of the dimethylamino(ethynyl)carbene complex [(CO) 5 WC(NMe 2 )CCH] (1) with n BuLi, CuI and BrCCSiMe 3 affords the dimethylamino(trimethylsilylbutadiynyl)carbene [(CO) 5 WC(NMe 2 )CCCCSiMe 3 ] (2) . Desilylation of 2 with KF/THF/MeOH gives [(CO) 5 WC(NMe 2 )CCCCH] (3) . The C‐stannylated carbene complex [(CO) 5 WC(NMe 2 )CCCCSnBu 3 ] (4) is obtained by deprotonation of 3 with n BuLi and subsequent reaction with Bu 3 SnCl. Pd‐catalyzed coupling of complex 4 with [ClRu(CO),Cp] affords the heterobimetallic pentadiynylidene complex [(CO) 5 WC(NMe,)CCCCRu‐(CO) 2 Cp] (5) The analogous Fe derivative [(CO),WC(NMe,)CCCCFe(CO) 2 Cp] ( 6 ) is obtained by sequential reaction of 3 with n BuLi and [IFe(CO) 2 Cp] Similarly, treatment of 3 first with n BuLi and then with half an equivalent of HgCl 2 affords the novel C 4 HgC 4 ‐bridged biscarbene complex [(CO) 3 WC(NMe 2 )CCCCHgCCCCC(NMe 2 )W(CO) 5 ]( 7 ) All new compounds are stable at room temperature. Spectroscopic data suggest weak interaction of the metal centers in 5 – 7 .