Reaction of the butterfly cluster nido-Ru4(CO)13(mu3-PPh) (1) with 1,3-diynes RC=CC=CR (R = Ph, Me, SiMe3) occurs under thermal conditions affording, as the first-formed products, the 62-electron clusters nido-RU4(CO)10(mu-CO)2{mu4-eta1,eta1,eta2-P(Ph)C(C=CR)CR} (R = Ph, 2a; R = SiMe3,2b; R = Me, 2c). Formation of 2a-c involves facile P-C bond formation retaining the 62-cluster valence electron count (CVE) associated with the butterfly skeletal framework. Coordination of a single acetylenic triple bond of the 1,3-diyne fragment in 2a-c affords an overall six electron donor P(Ph)C(C=CR)CR fragment. A single-crystal X-ray structure determination of 2c was carried out: 2c crystallizes as monoclinic crystals, space group P2(1)/n with unit cell dimensions a = 9.800(2) angstrom, b = 25.364(7) angstrom, c = 12.722(4) angstrom, beta = 98.50(2)-degrees, V = 3127.6(15) angstrom3, and Z = 4. The structure was solved and refined to R and R(w) values of 0.0235 and 0.0337, respectively, on the basis of 4670 observed (F greater-than-or-equal-to 6.0sigma(F)) data. The structure of 2c revealed that the acetylene was bonded in a mu3-eta2-manner to the Ru2P open triangle of the Ru3P square base reinforcing the view that the phosphinidene fragment behaves as an integral part of the skeletal framework. These addition reactions have been spectroscopically shown to proceed with high regiospecificity. Clusters 2a-c undergo a facile skeletal transformation concomitant with loss of a single carbon monoxide molecule to afford the 62-electron clusters closo-Ru4-(CO) 10(mu-CO) (mu4-PPh) 1mu4-eta1,eta1,eta2,eta2-(RC=C)C=CR}(R = Ph, 3a; R = SiMe3, 3b; R = Me, 3c). This skeletal rearrangement involves P-C bond cleavage and transfer of the mu3-PPh vertex originally basal to an apical position, adopting its more familiar role as a mu4-cluster stabilizing fragment. We determined that the transformations 2a to 3a and 2c to 3c occurred with opposite regiochemistry of rearrangement, a feature confirmed via single-crystal X-ray structures of both 3a and 3c. Crystals of 3a are triclinic, space group P1BAR, a = 9.255(1) angstrom, b = 9.677(1) angstrom, c = 20.531(2) angstrom, alpha = 80.47(1)-degrees, beta = 79.72(1)-degrees, gamma = 75.84(1)-degrees, V = 1739.9(3) angstrom3, and Z = 2; for 3c, monoclinic, space group Cc, a = 11.873(2) angstrom, b = 14.974(2) angstrom, c = 16.293(3) angstrom, beta = 106.15(1)-degrees, V = 2782.1(8) angstrom3, and Z = 4. The structures were solved and refined to the following R and R(w) values: 3a, R = 0.0291 and R(w) = 0.0459 on 6565 observed (F greater-than-or-equal-to 6.0sigma(F)) data; 3c, R = 0.0203 and R(w) = 0.0255 on 3112 observed (F greater-than-or-equal-to 6.0sigma(F)) data. The cluster core geometries of 3a-c are based on a closo pentagonal bipyramidal arrangement of Ru4PC2 atoms, consistent with current bonding theories (eight skeletal electron pairs, seven vertices). Of clusters 3a-C only 3a and 3b undergo further thermal transformation. These clusters decarbonylate smoothly to form the decacarbonyl clusters Ru4(CO)10(mu4-PPh)(mu4-eta1, eta1, eta3, eta3-RC=CC=CR) (R = Ph, 4a; R = SiMe3, 4b) in reasonable yields. A single-crystal X-ray structure determination of 4b revealed a square planar arrangement of metal atoms on which both acetylenic multiple bonds were coordinated, affording a novel 8e donor four carbonhydrocarbyl ligand for which a bis-mu3-(alkylidyne) dicarbide description is appropriate. A cluster electron count of 64 electrons is in accord with the effective atomic number rule and the presence of four M-M bonds. Crystals of 4b are orthorhombic, space group Pnma, a = 21.727(3) angstrom, b = 13.954(2) angstrom, c = 11.462(1) angstrom, V = 3475.0(8) angstrom3, and Z = 4. The structure was solved and refined to R = 0.0299 and R(w) = 0.0334 on 3979 observed (F greater-than-or-equal-to 6.0sigma(F)) data. Cluster 2a reacts with dihydrogen thermally (90-degrees-C n-heptane 60 min, 4 mol equiv) resulting in elimination of the corresponding trans monoene and formation of the known cluster H2Ru4(CO)12(mu3-PPh) 5.
