Cluster chemistry: LIII. Preparation and some substitution reactions of bis(arylimido)triruthenium complexes: X-ray structures of Ru 3(μ 3-NPh) (μ 3-NC 6 H 4 F-3) (CO) 9 and Ru 3(μ 3-NPh) 2(CO) 8(L) (L = CNC 6H 3Me 2-2,6 and PPh 3)

Abstract

Azoarenes, ArNNAr′, react with Ru 3(CO) 12 to give Ru 3(μ 3-NAr)(μ 3- NAr′)(CO)9 (Ar = Ph, Ar′ = Ph, C 6H 4Me-3, C 6H 4CF 3-3, C 6H 4F-3 ( 11), C 6H 4F-4; Ar = Ar′= C 6H 4Me-3) in moderate yields; for Ar = Ar′= Ph or C 6H 4Me-3, the mononuclear cyclometallated Ru(C 6H 3RNNC 6H 4R-3) 2(CO) 2 (R = H or Me) were also obtained in low yield. Fe 3(CO) 12 and azobenzene afford Fe 3(μ 3-NPh) 2(CO) 9 in very low yield. An X-ray study of 11 confirms the structural assignments made on the basis of the spectroscopic measurements: an Ru 3 triangle with a non-bonded Ru…Ru vector is capped on both sides by a μ 3-arylimido moiety. Electron transfer-catalysed reactions with isocyanides, tertiary phosphines and phosphites proceed to give CO-substituted products in moderate yields: complexes Ru 3(μ 3- NPh) 2(CO) 8(L) (L = CNC 6H 3Me 2-2,6 ( 15), PPh 3 ( 16), P(OMe) 3), {Ru 3(μ 3- NPh) 2(CO) 8} 2(μ-(PPh 2) 2C 2) and Ru 3(μ 3-NPh) 2(μ-LL)(CO) 7 (LL = dppm, dppe) were obtained. X-ray structural studies of 15 and 16 show that the isocyanide ligand occupies an axial position, whereas the tertiary phosphine takes up an equatorial position, both on a terminal ruthenium atom. Crystals of 11, 15 and 16 crystallize in the monoclinic system with space group P2 1/ n, a 11.496(2), b 14.020(2), c 15.735(2) Å, β 99.43(1)°, Z=4 for 11; space group P2 1/ n, a 11.933(2), b 18.952(2), c 14.370(4) Å, β 100.29(2)°, Z=4 for 15; and space group Pc, a 17.507(3), b 11.657(2), c 19.518(4) Å, β 100.41(2)°, Z = 4 for 16. The structures were refined by least-squares methods and at convergence R = 0.037, R w = 0.048 for 3653 statistically significant reflections for 11; R = 0.041, R w = 0.046 for 3903 reflections for 15; and R = 0.039, R w = 0.047 for 5291 reflections for 16.