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 Cp2MCl2 (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. The first siliconoids containing directly bonded transition‐metal fragments are readily accessible from ligato‐lithiated Si6 siliconoids and dichlorometallocenes (M=Zr, Hf). Charge‐neutral siliconoid ligands were obtained by introduction of a pending tetrylene functionality (E=Si, Ge, Sn). The corresponding Fe(CO)4 complexes were synthesized for proof of concept (silicon atoms shown as pink circles).