Structural studies on ruthenium carbonyl hydrides. Part 20. Ligand substitution on HRu3(mu-NC5H3CO2Me)(CO)(10) and H2Ru3(mu-NC5H3CO2Me)(2)(CO)(8). Crystal structures of (mu-H)Ru-3(mu-eta(2)-NC5H3CO2Me)(CO)(9)(PPh3) and (mu-H)(2)Ru-3(mu-eta(2)-NC5H3CO2Me)(2)(CO)(7)(PPh3)

Clusters of the series HRu3(mu-NC5H3CO2Me)(CO)(10-n)(PPh3)(n) (n = 0, 1) an d H2Ru3(mu-NC5H3CO2Me)(2)(CO)(8-n)(PPh3)(n) (n = 0, 1) have been prepared. X-ray crystallographic studies of HRu3(mu-NC5H3-5-CO2Me)(CO)(9)(PPh3) and H 2Ru3(mu-NC5H3-5-CO2Me)(2)(CO)(7)(PPh3) have been performed. The regiochemis try of PPh3 substitution in both is consistent with greater cis labilizatio n by the N-donor atom compared with the C-donor atom of the nicotinyl ligan d. The monohydrido-methyl nicotinate derivative, (mu-H)Ru-3(mu-eta(2)-NC5H3CO2 Me)(CO)(9)(PPh3), crystallizes in the orthorhombic space group Pbca (No. 61 ) with a = 22.891(3), b = 12.641(1), c = 24.694(3) Angstrom, V = 7145.6(14) Angstrom(3) and Z = 8. The structure was solved and refined to R = 260% fo r 2191 data with \F-0\ > 6 sigma(F-0). The Ru-3 triangle has interatomic di stances (in increasing order) of Ru(1)-Ru(3) = 2.854(1), Ru(2)-Ru(3) = 2.86 1(1) and Ru(1)-Ru(2) = 2.910(1) Angstrom. The nicotinate ligand bridges the cluster through axial sites on Ru(1) and Ru(2), with Ru(1)-N(1) = 2. 136(6) Angstrom and Ru(2)-C(41) = 2.088(7) Angs trom; the mu-hydride ligand (which was located and refined) also bridges th e Ru(1)-Ru(2) edge, in a diequatorial location, with Ru(1) H(1) = 1.69(5) A ngstrom, Ru(2)-H(1) = 1.72(5) Angstrom and angle Ru(1) H(1)-Ru(2) = 117.5(2 7)degrees. The PPh3 ligand occupies an equatorial site on Ru(1), with Ru(1) -P(1) = 2.365(2) Angstrom and angle Ru(2)-Ru(1)-P(1) = 111.5(1)degrees. The dihydrido-bis(methyl nicotinate) derivative, (mu-H)(2)Ru-3(eta(2)-NC5H3 -5-CO2Me)(2) (CO)(7)(PPh3), crystallizes in the monoclinic space group P2(1 )/c (No. 14) with a = 12.104(4), b = 27.810(7), c = 12.290(3) Angstrom, bet a = 96.55(2)degrees, V = 4110(2) Angstrom(3) and Z = 4. The structure was r efined to R = 7.96% for those 2761 reflections with \F-0\ > 3 sigma(F-0). D istances within the Ru-3 triangle are (in increasing order) Ru(2)-Ru(3)= 2. 846(2), Ru(1)-Ru(3) = 2.914(2) and Ru(1)-Ru(2) = 2.924(2) Angstrom. The nic otinate ligands are involved in diaxial bridges across Ru(1)-Ru(2) (with Ru (1)-N(51) = 2.122(13) and Ru(2)-C(52) = 2.100(16) Angstrom) and Ru(1)-Ru(3) (with Ru(3)-N(61) = 2.129(14) and Ru(1) C(62) = 2.053(16) Angstrom) in suc h a way that N(51) lies trans to C(62) on Ru(1) with angle N(51)-Ru(1)-C(62 ) = 161.5(6)degrees. Hydride ligands bridge the Ru(1)-Ru(2) and Ru(1)-Ru(3) bonds, while the PPh3 ligand occupies an equatorial site on Ru(3), with Ru (3)-P(1)= 2.379(3) Angstrom.