Synthesis and characterization of the phosphine derivatives of $C_{60}$ -Metal cluster (Triosmium, Trirhenium and Tetrairidium) complexes

Abstract

The present study involves the synthesis, structure, and electrochemical properties of the phosphine derivatives of C₆₀-metal cluster (triosmium, Trirhenium and Tetrairidium) complexes. In chapter 1, study of the new trirhenium-C₆₀ phosphine derivatives has been described. The treatment of $Re₃(μ-H)₃(CO)₉(μ₃-η²:η²:η²-C₆₀)$ (II-1) with 2.2 equiv of $Me₃NO$ in the presence of excess $PMe₃$ in chlorobenzene (CB) gave the bisphosphine-substituted $1,2-Re₃(μ-H)₃(CO)₇(PMe₃)₂(μ₃-η²:η²:η²-C₆₀)$ complex as two diastereomers, II-2a (major, 38 %) and II-2b (minor, 11 %). The corresponding reaction of II-1 with 3.3 equiv of Me3NO, produced the trisphosphine-substituted isomeric product $1,2,3-Re₃(μ-H)₃(CO)₆(PMe₃)₃(μ₃-η²:η²:η²-C₆₀)$ as two diastereomers, II-3a (major, 37 %) and II-3b (minor, 15 %). Complexes II-2a and II-3b have been characterized by spectroscopic methods and elemental analyses. Single crystal X-ray diffraction studies were obtained for II-2a and II-3b, despite their diastereomeric fluxionality. The hydrides were confirmed by 1H NMR spectroscopic method and directly located only for II-3a by X-ray diffraction. The molecular structure of II-2a confirms a face-capping $μ₃-η²:η²:η²-C₆₀$ ligand with one axial and one equatorial $PMe₃$ ligand on adjacent rhenium atoms, whereas that for II-3b exhibits pseudo-Cs symmetry with an additional equatorial $PMe₃$ on the third rhenium atom. Molecular structures for II-2b and II-3a are proposed by axial $PMe₃$ ligand placement and subsequent equatorial $PMe₃$ placement, based on ...