Electron compensating fragmentation of phenylethynyl ferrocenyltelluride in reactions with homoleptic metal carbonyls of Cr, Mo, W, Fe and Ru: Synthesis and structure of Te stabilized clusters

Abstract The alkynyl telluroether (phenylethynyl ferrocenyltelluride) (1) reacts with [M(CO)5(THF)]; (M = Cr, Mo, W) to form the monocoordinated adduct, [M(CO)5(Fc2Te2)] (2-4) and dicoordinated compounds [{M(CO)5}2(Fc2Te2)] (5-7) (Fc = ferrocenyl). Compounds 2-4 readily react with respective [M(CO)5(THF)] to give the corresponding 5-7. In contrast, reaction of 1 with [Fe(CO)5] leads to a scission of the Te-C bond of 1, reaction of the ensuing PhC C fragment and the TeFc fragment with ironcarbonyl to form the unusual fused ferracyclopentenone units, [{Fe(CO)4C(O)C(Ph)=C}2] (8) and the isomeric Fc2Te2 compounds, (9) [Fe2(CO)6(µ-TeFc)2] and 10 [Fe2(CO)6(µ-TeFc)2]. In addition, thermolytic reaction of [Ru3(CO)12] with 1 gives high nuclearity clusters [Ru4(CO)11{μ4-Te-η1:η1:η4-CC(Fc)C6H4}] (11) and [Ru4(CO)10{μ3-Te-η1: η1: η4:η2:η2-CC(Fc)C6H4}] (12) which are formed by Te-C bond breaking, C-C coupling and rearrangement. The easy cleavage of Te-Csp bond also displays the role of ligand for the formation of new clusters. The depth of fragmentation of phenylethynyl ferrocenyltelluride in the resulting complexes depends on the formal electron deficit of the decarbonylated metal fragment. Bonding properties of 11 and 12 have been discussed using the DFT studies.