Organotransition-metal Metallacarboranes 12

Alternative Title

Arene-metal-carborane triple-decker sandwiches. Designed synthesis of homo- and heterobimetallic complexes of cobalt, iron, ruthenium, and osmium


This paper describes the systematic preparation and characterization of new families of triple-decker sandwich complexes incorporating formal cyclo-Et2C2B3H3 4- bridging ligands, including the first species of this class containing second- or third-row transition metals. Complexes of general formula (L)M(Et2C2B3H3)M′(L) (M = Ru, Os; M′ = Co, Ru; L = cymene [p-isopropyltoluene], Cp, or C5Me5) were obtained in stepwise fashion via (1) synthesis of closo-(L)M(Et2C2B4H4) metallacarboranes, (2) “decapitation” (apex BH removal) of these complexes to give nido-(L)M(Et2C2B3H5), (3) bridge deprotonation to form the corresponding mono- or dianion, and (4) reaction of the anion with an arene metal halide to generate the desired triple-decker compound. In addition, the cobalt-iron triple-decker CpCo(Et2C2B3H3)FeCp was prepared via treatment of (η6-C8H10)Fe(Et2C 2B3H4)- with Na+Cp- and CoCl2 followed by air oxidation. The reaction of (CO)3RuCl2 with (C5Me5)-Co(Et2C2B3H 3)2- gave the “pseudo-triple-decker” complex (C5Me5)Co(Et2C2B3H 3)Ru(CO)3. The triple-deckers, especially those containing osmium, are susceptible to chlorination by RuCl3, OsCl3, or dichloromethane, forming exclusively the 4-chloro derivatives. All of the characterized triple-decker complexes are air-stable crystalline solids (except for the osmium-ruthenium species, which are air sensitive) and have been structurally characterized from their 11B and 1H NMR, infrared, visible-UV, and unit- and high-resolution mass spectra, further supported by X-ray crystallographic analyses of (cymene)Ru-(Et2C2B3H3)Ru(cymene) (10) and CpCo(Et2C2B3H3)Ru(cymene) (11a). Crystal data for 10: mol wt 561.13; space group P1; Z = 2; a = 10.409 (3), b = 11.268 (5), c = 12.002 (4) Å; α = 96.16 (3), β = 99.49 (2), γ = 106.69 (3)°; V = 1312 (2) Å3; R = 0.043 for 4777 reflections having Fo 2 > 3σ(Fo 2). Crystal data for 11a: mol wt 476.92; space group P21/c; Z = 4; a = 8.808 (6), b = 17.708 (8), c = 14.194 (8) Å; β = 103.50 (4)°; V = 2153 (4) Å3; R = 0.058 for 3289 reflections having Fo 2 > 3σ(Fo 2). © 1989 American Chemical Society.



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© 1989 American Chemical Society (ACS), All rights reserved.