ELECTRON-RICH CLUSTER CHEMISTRY - SYNTHESIS AND MOLECULAR AND ELECTRONIC-STRUCTURES OF THE SERIES OF CLUSTERS RU-4(CO)(13)(MU-PR(2))(2) WITH EXPANDED METAL FRAMEWORKS

The reaction of 2 equiv of dialkyl-, diaryl-, dialkoxy- or bis(dialkylamino)chlorophosphines, R(2)PCl (R = Cy, Et, Oft, NPr2i, Ph, Pr-i), with the 60-electron tetrahedral cluster anion [RU(4)(CO)(13)](2-) results in the partial opening of the RU(4) framework and the formation of [RU(4-) (CO)(13)(mu-PR(2))(2)] (1a, R = Ph; 1b, R = Pr-i; 1c, R = OEt; 1d, R = NPr2i; 1e, R = Cy; 1f, R = Et) in varying fields. These 64-electron phosphido-bridged clusters consist of planar RU(4) butterfly polyhedra possessing two normal and three elongated metal-metal bonds. The compounds have been fully characterized by IR and H-1, P-31, and C-13 NMR spectroscopy. Single-crystal X-ray structure determinations of 1a-d are also reported. Crystal data for 1a: RU(4)P(2)O(13)C(37)H(20).2CHCl(3), orthorhombic, space group P2(1)2(1)2, a 11.463(2) Angstrom, b = 15.818(3) Angstrom, c = 13.071(3) Angstrom, Z = 2. The structure was solved and refined to R = 0.0221 and R(w) = 0.0223 on the basis of 3411 observed (F greater than or equal to 6.0 sigma(F)) reflections. Crystal data for 1b: RU(4)P(2)O(13)C(25)H(28).CHCl3, triclinic, space group <P(1)over bar>, a 11.169(1) Angstrom, b = 12.488(2) Angstrom, c 14.040(3) Angstrom, alpha = 82.48(2)degrees, beta = 80.94(1)degrees, gamma = 84.46(1)degrees, Z 2. Refinement converged at R = 0.0225 and R(w) = 0.0263 on the basis of 5765 observed data. Crystal data for 1c: RU(4)P(2)O(1)7C(21)H(20).1/2C(6)H(6), triclinic, space group <P(1)over bar>, a = 9.273(2) Angstrom, b = 11.269(2) Angstrom, c = 17.512(2) Angstrom, alpha = 78.83(2)degrees, beta = 81.89(2)degrees, gamma = 77.23(2)degrees, Z = 2. The final R and R(w) values obtained were 0.0258 and 0.0322, respectively, using 7244 observed reflections. Crystal data for 1d: RU(4)P(2)N(4)O(13)C(37)H(56), monoclinic, space group P2(1)/m, a = 9.889(1) Angstrom, b = 23.913(3) Angstrom, c 10.789(1) Angstrom, beta = 106.96(2)degrees, Z = 2. The structure was solved and refined to R = 0.0243 and R(w) = 0.0259 for 4388 observed data. The clusters 1a-d exhibit significantly different elongation patterns of the Ru-Ru and Ru-P vectors as a consequence of the varying electronic effects of the phosphido bridges, a fact confirmed by EHRIO calculations. AU of the compounds 1a-f have a P-31 NMR resonance which is more shielded than in phosphido bridges across normal ruthenium-ruthenium bonds.