METALLKOMPLEXE MIT VERBRUECKENDEN DIMETHYLPHOSPHIDOLIGANDEN II. OEFFNUNG DER HYDRIDOBRUECKE IM +-KATION DURCH LEWIS-BASEN UND BILDUNG VON μ-FORMIMIDOYLKOMPLEXEN UEBER HYDRIDO(ISONITRIL)-UND μ-AMINOCARBINVERBINDUNGEN ALS ZWISCHENSTUFEN

Article abstract of DOI:10.1016/0022-328X(86)80063-8

The complex <(C5H5Co)2(μ-PMe2)2(μ-H)>PF6 (IIa) reacts with PMe3.PMe2H or P(OMe)3 in methanol by opening the hydride bridge and formation of PF6 (L = PMe3 (III); L = PMe2H (IV); L = P(OMe)3 (V)).A solution of the dimethylphosphine complex IV in nitromethane gives a mixture of products from which the compounds trans-<2>(PF6)2(VII) and <(C5H5Co)2(μ-PMe2)3>PF6 (VIII) have been isolated.The course of the reaction of IIa with isocyanides CNR (R = Me, Bu^t, Ph) is strongly solvent-dependent.In nitromethane, products of composition cis- and/or trans-<2>(PF6)2 (X, X II, XIV), <t)Co>2(μ-PMe2)>PF6 (XIII) and <(C5H5Co)2(μ-PMe2)2(μ,η²-NO2)>PF6 (XI) have been obtained.Compounds XI is also formed by treating IIa with KNO2 and CF3CO2H in methanol.The reaction of IIa with CNMe in methanol gives in addition to small amounts of cis/trans-X an isomeric mixture of PF6 (XV) and <(C5H5Co)2(μ-PMe2)2(μ-CNHMe)>PF6 (XVI).By varying the temperature, the two isomers can be obtained pure.In the presence of methylamine, the μ-aminocarbyne complex XVI rearranges quantitatively to produce the μ-formimidoyl compound <(C5H5Co)2(μ-PMe2)2(μ-HC=NMe)>PF6 (XX), the structure of which has been determined by X-ray analysis.This result proves for the first time that the formation of formimidoyl ligands by insertion of isocyanides in M-H or M-H-M bonds can occur with μ-aminocarbyne complexes as intermediates.Using methanol as the solvent, the synthesis of BF4 (IX), t)Co(μ-PMe2)2Co(H)C5H5>PF6 (XVII) and <(C5H5Co)2(μ-PMe2)2(μ-HC=NPh)>PF6 (XIX) has been achieved.