Synthesis and Reactivity of a Cyclooctatetraene‐Like Polyphosphorus Ligand Complex [Cyclo‐P<sub>8</sub>]
Christoph Riesinger, Fabian Dielmann, Robert Szlosek, A.V. Virovets, Manfred Scheer
Abstract
Abstract The thermolysis of Cp′′′Ta(CO) 4 with white phosphorus (P 4 ) gives access to [{Cp′′′Ta} 2 (μ,η 2 : 2 : 2 : 2 : 1 : 1 ‐P 8 )] ( A ), representing the first complex containing a cyclooctatetraene‐like (COT) cyclo ‐P 8 ligand. While ring sizes of n >6 have remained elusive for cyclo ‐P n structural motifs, the choice of the transition metal, co‐ligand and reaction conditions allowed the isolation of A . Reactivity investigations reveal its versatile coordination behaviour as well as its redox properties. Oxidation leads to dimerization to afford [{Cp′′′Ta} 4 (μ 4 ,η 2 : 2 : 2 : 2 : 2 : 2 : 2 : 2 : 1 : 1 : 1 : 1 ‐P 16 )][TEF] 2 ( 4 , TEF=[Al(OC{CF 3 } 3 ) 4 ] − ). Reduction, however, leads to the fission of one P−P bond in A followed by rapid dimerization to form [K@[2.2.2]cryptand] 2 [{Cp′′′Ta} 4 (μ 4 ,η 2 : 2 : 2 : 2 : 2 : 2 : 2 : 2 : 1 : 1 : 1 : 1 ‐P 16 )] ( 5 ), which features an unprecedented chain‐type P 16 ligand. Lastly, A serves as a P 2 synthon, via ring contraction to the triple‐decker complex [{Cp′′′Ta} 2 (μ,η 6 : 6 ‐P 6 )] ( B ).