Cluster chemistry: LIII. Preparation and some substitution reactions of bis(arylimido)triruthenium complexes: X-ray structures of Ru3(μ 3-NPh) (μ3-NC6 H4 F-3) (CO)9 and Ru3(μ3-NPh)2(CO)8(L) (L = CNC6H3Me2-2,6 and PPh3)

Abstract Azoarenes, ArNNAr′, react with Ru3(CO)12 to give Ru3(μ3-NAr)(μ3- NAr′)(CO)9 (Ar = Ph, Ar′ = Ph, C6H4Me-3, C6H4CF3-3, C6H4F-3 (11), C6H4F-4; Ar = Ar′= C6H4Me-3) in moderate yields; for Ar = Ar′= Ph or C6H4Me-3, the mononuclear cyclometallated Ru(C6H3RNNC6H4R-3)2(CO)2 (R = H or Me) were also obtained in low yield. Fe3(CO)12 and azobenzene afford Fe3(μ3-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 Ru3 triangle with a non-bonded Ru…Ru vector is capped on both sides by a μ3-arylimido moiety. Electron transfer-catalysed reactions with isocyanides, tertiary phosphines and phosphites proceed to give CO-substituted products in moderate yields: complexes Ru3(μ3- NPh)2(CO)8(L) (L = CNC6H3Me2-2,6 (15), PPh3 (16), P(OMe)3), {Ru3(μ3- NPh)2(CO)8}2(μ-(PPh2)2C2) and Ru3(μ3-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 P21/n, a 11.496(2), b 14.020(2), c 15.735(2) A, β 99.43(1)°, Z=4 for 11; space group P21/n, a 11.933(2), b 18.952(2), c 14.370(4) A, β 100.29(2)°, Z=4 for 15; and space group Pc, a 17.507(3), b 11.657(2), c 19.518(4) A, β 100.41(2)°, Z = 4 for 16. The structures were refined by least-squares methods and at convergence R = 0.037, Rw= 0.048 for 3653 statistically significant reflections for 11; R = 0.041, Rw = 0.046 for 3903 reflections for 15; and R = 0.039, Rw= 0.047 for 5291 reflections for 16.

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