Einkernige Carbonylmetall-Komplexe des Eisens und Rutheniums, M(CO)n[P(C7H7)3] (M=Fe, Ru; n=4,3,2), mit dem mehrzähnigen Liganden Tri(1-cyclohepta-2,4,6-trienyl)phosphan

A series of trigonal-bipyramidal complexes of the type M(CO)n[P(C7H7)3] (M=Fe, Ru; n=4,3,2) has been investigated in which the phosphorus atom of the ligand tri(1-cyclohepta-2,4,6-trienyl)phosphane, P(C7H7)3 (1), is coordinated in an axial position and up to two olefinic side-arms may be used for additional coordination to the metal in equatorial positions. The reaction of either Fe2(CO)9 or Fe3(CO)12 with 1 in THF solution leads to the phosphane complex Fe(CO)4[P(C7H7)3] (4a); the ruthenium analogue 4b is obtained from Ru3(CO)12 under irradiation. Stepwise photo-elimination of two equatorial CO ligands can be used to convert 4a,b through the intermediate M(CO)3[P(C7H7)2(η2-C7H7)] (M=Fe (5a), Ru (5b)) into M(CO)2[P(C7H7)(η2-C7H7)2] (M=Fe (6a), Ru (6b)). In C6D6 solution, the bis(olefinic) complexes 6a,b slowly isomerize to give the orange end-products M(CO)2[P(C7H7)2(η4-C7H7)] (7a,b) in which only one of the three seven-membered rings is coordinated to the metal in the form of a norcaradienyl substituent. The new complexes were characterized by a consistent set of 1H-, 13C- and 31P-NMR spectra, and the molecular geometry of 6a has been determined by a single-crystal structure analysis.