Chemistry of C-Trimethylsilyl-Substituted Heterocarboranes. 20. Synthetic and Structural Studies on Sandwich Ln(III) Carborane Clusters. II (Ln(III) = Sm, Gd, Dy, Ho, Er)

The room-temperature reactions of closo-exo -4,5-[(μ-H) 2 Li(TMEDA)]-1-Li(TMEDA)-2,3-(SiMe 3 ) 2 -2,3-C 2 B 4 H 4 with anhydrous LnCl 3 (Ln = Sm, Gd, Dy, Ho, Er), in molar ratios of 2:1 in dry benzene (C 6 H 6 ), produced the sandwich paramagnetic species [Li(TMEDA) 2 ][1-Cl-1-(μ-Cl)-2,2‘,3,3‘-(SiMe 3 ) 4 -5,6-[(μ-H) 2 Li(TMEDA)]-4,4‘,5‘-[(μ-Η) 3 Li(TMEDA)]-1,1‘- commo -Ln(2,3-C 2 B 4 H 4 ) 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 1 H, 13 C, 11 B, and 7 Li 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 μ B per metal atom, respectively.