Polycarbon ligands: Synthesis and characterization of the phosphinodiynes Ph(2)PC C-C CR (R=Bu(t), Ph, SiMe(3)), the mu-eta(1),eta(2)(alpha,beta)-butadiynyl complexes Ru-2(CO)(6)(mu-PPh(2))(mu-eta(1),eta(2)(alpha,beta)-C C-C CR), and the molecular structure of a cobalt carbonyl derivative Ru-2(CO)(6)(mu-PPh(2))(mu-eta(1),eta(2)(alpha,beta):mu-eta(2),eta(2)(gamma,delta)-C C-C CBu(t))Co-2(CO)(6)

The phosphino-diynes (PPh(2)C=C-C=CR) (R=Bu(t), Ph, SiMe(3)) are obtained in excellent yield from the corresponding diyne anions RC=C-C=C- by quenching with PPh(2)Cl. Monosubstitution on Ru-3(CO)(12) yields the trinuclear clusters Ru-3(CO)(11)(PPh(2)C=C-C=CR), which upon thermolysis afford the butadiynyl complexes Ru-2(CO)(6)(mu-eta(1), eta(alpha beta)(2)-C=C-C=CR)(mu-PPh(2)) (R=Bu(t), 7a; R=Ph, 7b; R=SiMe(3), 7c) as the major products. The full characterization of the series of 2 compounds (7a-c) Ru-2(CO)(6)(mu-eta(1),eta(alpha,beta)(2)-C=C-C=CR)(mu-PPh(2)) is reported including an X-ray diffraction study of 7a. Crystals of 7a are monoclinic, a=9.849(2), b=9.886(2), c=28.368(9) Angstrom, beta=95.18(2)degrees, space group P2(1)/n, and Z=4; refinement converged to R=0.0243 (R(W)=0.0253). The structure shows that the tetracarbon chain is bonded to the first metal atom by a simple M-C sigma bond and to the second via a dative pi interaction leaving an outer alkyne unit uncoordinated. In the reaction between 7a and cobalt carbonyl, a Co-2(CO)(6) moiety becomes attached to the -CgammaCdelta- bond in a tetrahedral arrangement to give the tetranuclear mixed-metal species Ru-2(CO)(6)(mu-PPh(2))(mu-eta(1),eta(alpha,beta)(2):mu-eta(2),eta(gamma,delta)(2)-C=C-C=Bu(t))CO2(CO)(6) 8, as confirmed by X-ray crystallography: triclinic, a=9.9969(9), b=11.3018(9), c=17.268(1) Angstrom, alpha=90.653(6)degrees, beta=100.911(6)degrees, gamma=110.465(5)degrees,space group <P(1)over bar> and Z=2; refinement converged to R=0.0222(R(W)=0.0264).