Indirect and Direct Grafting of Transition Metals to Siliconoids

Unsaturated charge-neutral silicon clusters (siliconoids) are important as gas-phase intermediates between molecules and the elemental bulk. With stable zirconocene- and hafnocene-substituted derivatives, we here report the first examples containing directly bonded transition-metal fragments that are readily accessible from the ligato-lithiated Si6 siliconoid (1Li) and Cp2 MCl2 (M=Zr, Hf). Charge-neutral siliconoid ligands with pending tetrylene functionality were prepared by the reaction of amidinato chloro tetrylenes [PhC(NtBu)2 ]ECl (E=Si, Ge, Sn) with 1Li, thus confirming the principal compatibility of such low-valent functionalities with the unsaturated Si6 cluster scaffold. The pronounced donor properties of the tetrylene/siliconoid hybrids allow for their coordination to the Fe(CO)4 fragment.