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-triangle is capped on one face by the ferrocenyl phosphido moiety acting as an overall six-electron donor. It is bonded to the cluster via one phosphorus atom, one carbon atom from the C5H4 ring, and the iron atom. Two semibridging carbonyls are also present in each structure. Crystals of {mu3-[eta5-C5H4)2Fe]P[(eta3-C5H4)Fe(eta5-C5H5)]-Fe,P,P,C}Os3(CO)9 (5a) are triclinic, a 12.304(1), b 12.336(2), c 10.886(2) angstrom, alpha 115.38(2), beta 92.34(1), gamma 91.76(1)-degrees, Z = 2, space group P1BAR, and those of {mu3-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, space group P1BAR. The structures were solved by heavy atom methods and were 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 3sigma(I), respectively.