Chemistry of C-trimethylsilyl-substituted heterocarboranes .19. Synthetic and structural studies on trinuclear Ln(III) carborane clusters [Ln(III)=Sm, Gd, Tb, Dy, Ho] .1. Conversion to sandwiched manganese(II) and cobalt(III) carborane complexes

The reaction of closo-exo-4,5-Li(THF)(2)-1-Li(THF)(2)-2,3-(SiMe(3))(2)C2B4H4 with anhydrous LnCl(3) (Ln = Sm, Gd, Tb, Dy, Ho), in a molar ratio of 2:1 in dry benzene (C6H6), produced the sandwiched paramagnetic species {[eta(5)-1-Ln-2,3-(SiMe(3))(2)-2,3-C2B4H4](3)[(mu(2)-1-Li-2,3-(SiMe(3))(2)- 2,3-C2B4H4)(3)(mu(3)-OMe)][mu(2)-Li(C4H8O)](3)(mu(3)-O)} (Ln = Sm (1), Gd (2), Tb (3), Dy (4), Ho (5)) in 59%, 58%, 49%, 52%, and 59% yields, respectively. All compounds were characterized by IR spectroscopy and by single-crystal X-ray diffraction studies; compound 1 was also characterized by H-1, B-11, and C-13 NMR spectroscopy. Compounds 1-5 are isostructural clusters consisting of three half-sandwich lanthanacarboranes, three lithiacarboranes, three bridging lithium atoms, and three THF molecules of solvation. Their structures are such that the nine metal atoms form a tricapped trigonal prism with the lanthanide metals at the capping positions. The reaction of 2 with MnCl2 in benzene, followed by the addition of TMEDA, gave a dinuclear manganacarborane sandwich complex, 4,4',5,5'-Mn(TMEDA)-1,1'-commo-Mn[2,3-(SiMe(3))(2)-2,3-C2B4H4](2) (6) Compound 6 was characterized on the basis of its elemental analysis and IR spectrum and also by X-ray diffraction. The reaction of 1 with CoCl2 in dry benzene, followed by the addition of TMEDA, gave the cobalt(III) sandwich complex, Li(TMEDA)(2){1,1'-commo-Co[2,3-(SiMe(3))(2)-2,3-C2B4H4](2)} (7). Complex 7 was characterized on the basis of H-1, Li-7, B-11, and C-13 NMR spectra and IR spectra and also by X-ray diffraction.