CRYSTAL AND MOLECULAR-STRUCTURES OF OS3(CO)9[MU(3)-(C5H4PR)FE(C5H4)] (R = FC OR PH), 2 MOLECULES WITH FE -] OS BONDS

The thermal reaction between Os3(CO)12 and Fe(C5H4)2PPh affords Os3(CO )9[mu3-(C5H4PPh)Fe(C5H4)](5b) (70%) as the only major product. Heating a solution of Os3(CO)11(PFc2Ph) (FcH = (eta-C5H5)2Fe) in octane for 3 h gives the related molecule Os3(CO)9[mu3-(C5H4PFc)Fe(C5H4)] (5a) in low yield (5%). The structures of 5a and 5b have been established by X -ray crystallography, revealing in each case that a closed Os3-triangl e is capped on one face by the ferrocenyl phosphido moiety acting as a n overall six-electron donor. It is bonded to the cluster via one phos phorus atom, one carbon atom from the C5H4 ring, and the iron atom. Tw o semibridging carbonyls are also present in each structure. Crystals of )2Fe]P[(eta3-C5H4)Fe(eta5-C5H5)]-Fe,P,P,C}Os3(CO)9 (5a) are triclin ic, a 12.304(1), b 12.336(2), c 10.886(2) angstrom, alpha 115.38(2), b eta 92.34(1), gamma 91.76(1)-degrees, Z = 2, space group P1BAR, and th ose of u3-eta4-[(eta5-C5H4)2Fe]P(C6H5)]-Fe,P,P,C}OS3(CO)9 . 0.5CH2Cl2 (5b) are also triclinic, a 12.427(2), b 13.061(1), c 9.209(1) angstrom , alpha 96.562(8), beta 91.25(1), gamma 76.956(9)-degrees, Z = 2, spac e group P1BAR. The structures were solved by heavy atom methods and we re refined by full-matrix least-squares procedures to R = 0.036 and 0. 031 for 5884 and 4716 reflections with I greater-than-or-equal-to 3sig ma(I), respectively.