BIS(PHENYLETHYNYL)HAFNOCENE AS AN ORGANOMETALLIC CHELATE LIGAND

The application of (eta5-C5H4SiMe3)2Hf(C=CPh)2 (1) as an organometallic chelate ligand towards different organometallic building blocks will be discussed. 1 reacts with Ni(CO)4 (2) or Co2(CO)8 (4) to yield {(eta5-C5H4SiMe3)2Hf(C=CPh)2}M(CO) (M=Ni: 3, M=Co: 5) and (eta5-C5H4SiMe3)2Hf(C=CPh) {mu-(eta2-C=CPh)-Co2(CO)6] (6). In 6 one of the two phenylethynyl units is eta2-side-on coordinated to Co2(CO)6 forming a 1, 2-dicobaltatetrahedrane unit. However, the reaction of 1 with Fe2(CO)9 (7) affords (eta5-C5H4SiMe3)2Hf[(eta2-C=CPh)Fe(CO)4]2 (8), a compound, in which both of the phenylethynyl ligands are eta2-side-on coordinated to Fe(CO)4 complex fragments. All new synthesized compounds have been characterized by analytical and spectroscopic data. Additionally, the structure of 3 was established by X-ray diffraction study.