A new family of C2B3-bridged tetradecker sandwich complexes, having cymene rather than cyclopentadienyl end rings, has been synthesized via reactions of metal ions with nido-(p-CHMe(2)C(6)H(4)Me)Ru(Et(2)C(2)B(3)H(3)-5-Y)(-) anions that are iso electronic analogues of the nido-(eta(5)-C(5)Me(5))Co(Et(2)C(2)B(3)H(3)-5-Y)(-)synthons employed in earlier work. Bridge-deprotonation of CyRu(Et(2)C(2)B(3)H(4)-5-Y) (Cy = p-isopropyltoluene; 3, Y = Me; 6, Y = Cl), followed by treatment with CoCl2 in THF and separation of the products on silica in air, afforded the tetradecker sandwiches [CyRu(2,3-Et(2)C(2)B(3)H(2)-5-Y)]Co-2 (8a, Y = Me; 8b, Y = Cl) as the major products, isolated as air-stable paramagnetic green crystals in 40% and 55% yield, respectively. In addition, the minor products CyRu(Et(2)C(2)B(3)H(2)-5-Me)Co(Et(2)C(2)B(3)H(2)-5-Et)RuCy (8c) and CyRu-(Et(2)C(2)B(3)H(2)-5-Cl)Co(Et(2)C(2)B2B(3)H(3))RuCY (8d) were obtained. The formation of 8b proceeds via a cobalt-protonated diamagnetic complex [CyRu(2,3-Et(2)C(2)B(3)H(2)-5-Cl)]2CoH (7b) which was isolated and characterized; 8a is assumed to form via an analogous intermediate 7a although this species was not isolated. A similar reaction of 3(-) with NiCl2 gave moderately air-stable, diamagnetic [CyRu(2,3-Et(2)C(2)B(3)H(2)-5-Me)]Ni-2 (9). Reactions of the anion of the B(4,5,6)-trimethyl complex CYRu(Et(2)C(2)B(3)Me(3)H(2)) with CoCl2 and NiCl2 generated the corresponding tetradecker products [CyRu(2,3-Et(2)C(2)B(3)Me(3))]Co-2 (10) and [CyRu(2,3-Et(2)C(2)B(3)Me(3))]Ni-2 (11) in low yields. The new compounds were characterized via H-1 and/or C-13 NMR, IR, UV-visible, and mass spectra, supported by X-ray crystal structure determinations on 8a, 8c, and 9, which established the tetradecker sandwich geometry. The proton NMR spectrum of paramagnetic 8a was completely assigned via the technique of correlated spectroscopy, involving generation of the diamagnetic anion 8a(-) via stepwise reduction of the neutral compound. Crystal data for 8a: Ru2CoClC34.5B6H59, space group <P(1)over bar> (triclinic); a = 13.631(5) Angstrom, b = 16.447(5) Angstrom, c = 9.008(3) alpha = 100.07(3)degrees, beta = 108.12(3)degrees, gamma 94.03(3)degrees; Z = 2; R = 0.038 for 5527 independent reflections. Crystal data for 8c: Ru2Co2C35B6H60, space group P2(1)/n (monoclinic); a = 12.781(3) Angstrom, b = 11.120(4) Angstrom, c = 26.214(4) Angstrom, beta = 96.71 degrees; Z = 4; R = 0.031 for 3052 observed reflections. Crystal data for 9: Ru2NiC34B6H58, space group <P(1)over bar> (triclinic); a = 12.577(7) Angstrom, b = 14.330(6) Angstrom, c = 11.671(7) Angstrom, alpha = 113.24(4)degrees, beta = 111.71(4)degrees, gamma = 83.24(4)degrees; Z = 2; R = 0.028 for 4073 independent reflections.
