187Os, 31P and 17O NMR study of carbonylated and alkylated (p-cymene)OsI (L)PR3 complexes

Article abstract of DOI:10.1016/S0022-328X(97)00376-8

Series of complexes of the types [(p-cymene)OsI(CO)PR₃][PF₆], (p-cymene)OsI(phenylethynyl)PR₃, (p-cymene)OsI(alkyl)PR₃ have been prepared and investigated by ¹⁸⁷Os, ³¹P and ¹⁷O NMR spectroscopy. The structures of (p-cymene)OsI(C=CPh)PMe₃ (3a) and (p-cymene)OsI(C=CPh)PⁱPr₃ (3c) have been determined by X-ray diffraction. A mechanistic study of the formation of the metallacycle 8A formed by intramolecular trans-alkylation from (p-cymene)OsI₂PⁱPr₃ (1c) in the presence of Al₂Me₆ is presented. As shown by time-dependent ³¹P NMR, (p-cyrnene)OsI(Me)PⁱPr₃ (6c) is formed as an intermediate. ¹⁸⁷Os,¹³C coupling constants in Cp- and Cp*Os(CO)₂Me (14 and 15) have been determined from ¹³C-filtered (¹H,¹⁸⁷Os)-HMQC correlation spectra and are interpreted in comparison with the ⁵⁷Fe,¹³C data of the corresponding iron complexes.