Journal of Organometallic Chemistry 564 (1998) 277–281 Synthesis and reactivity of cyclopentadienyl chloro, imido and alkylidene tungsten (VI) complexes

This paper describes the synthesis and characterization of alkylidene pentamethylcyclopentadienyl imido tungsten(VI) com-plexes via a-hydrogen abstraction processes from suitable alkyl derivatives. Reaction of WCp*Cl4 with one equivalent of NH2R (R tBu, 2,6-Me2–C6H3), two equivalents of NEt3 and subsequent oxidation with PCl5 affords the pentamethylcyclopentadienyl imido tungsten derivatives, WCp*(NtBu)Cl3 2 and WCp*(N-2,6-(Me2)–C6H3)Cl3 4. Alkylation of complexes 2 and 4 with 1.5 equivalents of ZnMe2 under appropriate conditions yields the trimethyl derivatives WCp*(N tBu)Me3 5 and WCp*(N-2,6-(Me2)– C6H3)Me3 6. Exposure of complex 6 to sun-light leads to the formation of WCp*(N-2,6-(Me2)–C6H3)(CH2)Me 7 through a a-hydrogen abstraction process. Analogously, complex 2 reacts with 1.5 equivalents of Mg(CH2Ph)-(thf)2 or three equivalents of LiCH2SiMe3 to give the alkylidene complexes, WCp*(N tBu)(CHPh)(CH2Ph) 8 and WCp*(NtBu)(CHSiMe3)Cl 9, through a spontaneous a-hydrogen abstraction process in these cases. © 1998 Elsevier Science S.A. All rights reserved