A 2,2′-diphosphinotolane as a versatile precursor for the synthesis of P-ylidic mesoionic carbenes reversible C-P bond formation

• Published in: Chemical science (Cambridge) 2021-03, Vol.12 (1), p.3693-371
• Main Authors: Wagner, Hannah K, Wadepohl, Hubert, Ballmann, Joachim
• Format: Article
• ISSN: 2041-6520; 2041-6539
• DOI: 10.1039/d0sc06128j

A metal-templated synthetic route to cyclic (aryl)(ylidic) mesoionic carbenes ( CArY-MIC s) featuring an endocyclic P-ylide is presented. This approach, which requires metal templates with two cis -positioned open coordination sites, is based on the controlled cyclisation of a P , P ′-diisopropyl-substituted 2,2′-diphosphinotolane ( 1 ) and leads to chelate complexes coordinated by a phosphine donor and the CArY-MIC carbon atom. The C-P bond formation involved in the former partial cyclisation of 1 proceeds under mild conditions and was shown to be applicable all over the d-block. In the presence of a third fac -positioned open coordination site, the P-C bond formation was found to be reversible, as shown for a series of molybdenum complexes. DFT modelling studies are in line with an interpretation of the target compounds as CArY-MIC s. A metal-templated synthesis of cyclic (aryl)(ylidic)mesoionic carbene complexes ( CArY-MICs ) is presented. In the case of molybdenum carbonyls, the crucial P-C bond formation, which occurs during CArY-MIC formation, was found to be reversible.