Addition von Phosphanen an das Cα-Atom von Allenyliden(pentacarbonyl)chrom und Umlagerung in Phosphan-Komplexe

Article abstract of DOI:10.1016/0022-328X(94)05210-3

The allenylidene(pentacarbonyl)chromium complex (CO)5Cr (1a) adds phosphines PR3 at the C_α atom to give ylide complexes, (CO)5Cr- (PR3 = PMe3 (2), PHPh2 (3), PH2Mes (7) (Mes = C6H2Me3-2,4,6)).At room temperature complex 3 slowly rearranges to the allenylphosphine complex (CO)5CrPPh2 (4).The structure of 4 was established by an X-ray structure analysis.The adduct 7 obtained from 1a and PH2Mes, however, could not be detected.It immediately isomerizes to the alkynylphosphine complex (CO)5CrPH(Mes)C-CH(C6H4NMe2-p)2> (8).At room temperature the ylide complex 5, formed by addition of PHPh2 to the C_α atom of the allenylidene complex (CO)5Cr=C=C=C(o-C6H4)2O (1b), rearranges in CH2Cl2 in the presence of excess PHPh2 to give a binuclear bisphosphine complex (6). 6 corresponds to the product of the chemo-, regio- and stereo-selective dimerization of the allenylphosphine complex analogous to 4. Keywords: Chromium; Phosphane complexes; Allenylidene complexes; Nucleophilic addition; Ylide complexes