Chemistry of C-trimethylsilyl-substituted heterocarboranes .20. Synthetic and structural studies on sandwich Ln(III) carborane clusters .2. (Ln(III)=Sm, Gd, Dy, Ho, Er)

The room-temperature reactions of closo-exo-4,5-[(mu-H)(2)Li(TMEDA)]-1-Li(TMEADA)-2,3-(SiMe(3))(2)-2,3-C2B4H4 with anhydrous LnCl(3) (Ln = Sm, Gd, Dy, Ho, Er), in molar ratios of 2:1 in dry benzene (C6H6), produced the sandwich paramagnetic species [Li(TMEDA)(2)][1-Cl-1-(mu-Cl)-2,2',3,3'-(SiMe(3))(4)-5,6-[mu-H)(2)Li(TMEADA)]-4,4',5'-[(mu-H)(3)Li(TMEADA)]-1,1'-commo-Ln(2,3-C2B4H4)2] (Ln = Sm (1), Gd (2), Dy (3), Ho (4), Er (5)) in yields of 65%, 88%, 71%, 90%, and 93%, respectively. The compounds were characterized by IR spectroscopy, magnetic susceptibility measurements, and single-crystal X-ray diffraction studies. Compounds 2 and 3 were further characterized by EPR spectroscopy, and compound 1 was also characterized by H-1, C-13, B-11, and Li-7 NMR spectroscopy. All compounds are bent-sandwich complexes in which a Ln(III) atom is coordinated to two carborane ligands and two chloride ions. The room-temperature magnetic susceptibilities of 1-4 were found to be 1.1, 7.3, 9.4, and 10.1 mu(B) per metal atom, respectively.