The first mononuclear η8-coordinated pentalene complex: synthesis and molecular structure of [Ta{η8-C8H4(SiMe3) 2-1,4}Cl3]

Treatment of [TaCl 2 Me 3 ] with Li 2 (cot″) (cot″ = 1,4-bis(trimethylsilyl)cyclooctatetraene] affords [Ta(η-cot″)Me 3 ], which reacts with [NHPr i 2 Et]Cl in dichloromethane to yield the complex [Ta{η 8 -C 8 H 4 (SiMe 3 ) 2 -1,4}Cl 3 ]; X-ray crystallography shows the latter to contain a pentalene ligand bound through all eight carbons to a single tantalum centre.