The synthesis of [Ru5C(CO)15] by the carbonylation of [Ru6C(CO)17] and the reactions of the pentanuclear cluster with a variety of small molecules: the X-ray structure analyses of [Ru5C(CO)15], [Ru5C(CO)15(MeCN)], [Ru5C(CO)14(PPh3)], [Ru5C(CO)13(PPh3)2], and [Ru5(µ-H)2C(CO)12{Ph2P(CH2)2PPh2}

Abstract

The hexaruthenium cluster [Ru6C(CO)17] reacts with CO at 70 °C and 80 atm to produce [Ru5C(CO)15](1) and [Ru(CO)5]. Complex (1) crystallises in space group P21/c with a= 16.448(3), b= 14.274(2), c= 20.834(4)Å, β= 91.36(2)°, and Z= 8. The structure was found to be isomorphous with the analogue [Os5C(CO)15], and was refined to R= 0.051 for 3 256 diffractometer data. The five Ru atoms adopt a square-pyramidal geometry with an exposed carbido-atom lying 0.11 (2)Å beneath the basal plane. Reaction of complex (1) with the nitrogen-donor ligand MeCN yields the adduct [Ru5C(CO)15(MeCN)](2) which exhibits a bridged butterfly arrangement of metal atoms with a central carbido-atom. The complex crystallises in space group P21/n with a= 14.116(6), b= 18.167(7), c= 10.276(4)Å, β= 95.14(3)°, and Z= 4; the structure was solved by direct methods and difference techniques and refined to R= 0.047 for 1 604 diffractometer data. Reactions of complex (1) with tertiary phosphine ligands PR3[R = Ph (3) or MePh2(4)] or Ph2P(CH2)nPPh2[n= 1 (5) or 2 (6)] produce the substituted complexes [Ru5C(CO)15-m(PR3)m][m= 1 (3a, 4a), 2 (3b, 4b), or 3 (3c, 4c)] or [Ru5C(CO)13{Ph2P(CH2)nPPh2}][n= 1 (5) or 2 (6)]. The structures of these complexes are closely related to that of (1). Complex (3a) crystallises in space group Pn with a= 9.953(2), b= 12.247(2), c= 14.703(3)Å, β= 91.23(2)°, and Z= 2, (3b) in space group P21/c with a= 15.923(4), b= 12.494(3), c= 25.210(7)Å, β= 93.28(2)°, and Z= 4. Both structures were solved by a combination of direct methods and Fourier techniques and were refined to R= 0.021 for 3 305 reflections (3a) and R= 0.039 for 4 127 reflections (3b), respectively. Hydrogenation of (6) gives the dihydro-complex [Ru5(µ-H)2C(CO)12{Ph2P(CH2)2Ph2}] which crystallises in space group P21 with a= 12.210(4), b= 18.602(6), c= 18.409(6)Å, β= 97.63(2)°, and Z= 4. The structure was solved using the same techniques as the other complexes and refined to R= 0.064 for 3 510 diffractometer data. Treatment of complex (1) with halide ions gives the anionic clusters [Ru5C(CO)15X]–(X = F, Cl, Br, or I) whose structures are similar to that of (2). Protonation of these anions gives the monohydrido-clusters [Ru5H(C)(CO)15X]. With Cl2 and Br2 complex (1) undergoes fragmentation to give dimers [Ru2(CO)6X4](X = Cl or Br); in contrast, reaction with I2 gives [Ru5C(CO)15I2].