Synthesis, Structural Characterization, and Reactivity of Lanthanacarboranes Incorporating “Carbons-Adjacent” nido- and arachno-Carborane Anions of the C₂B₁₀ System

Group 1 salts of “carbons-adjacent” carborane anions of the C 2 B 10 system are useful synthons for the production of other metallacarboranes. Treatment of [{ μ -1,2-[ o -C 6 H 4 (CH 2 ) 2 ]-1,2-C 2 B 10 H 10 } 2 Na 4 (THF) 6 ] n ( 2 ) with 2 equiv of LnCl 3 gave the novel half-sandwich lanthanacarboranes [ η 6 -{ μ -1,2-[ o -C 6 H 4 (CH 2 ) 2 ]-1,2-C 2 B 10 H 10 }Yb(NC 5 H 5 ) 3 {Na(NC 5 H 5 ) 2 } 0.5 ] 2 ( μ -Cl) ( 4 ) and [ η 6 -{ μ -1,2-[ o -C 6 H 4 (CH 2 ) 2 ]-1,2-C 2 B 10 H 10 }]LnCl(THF) 3 (Ln = Nd ( 5 ), Er ( 6 ), Y ( 7 )), which represent the first lanthanacarboranes containing a terminal Ln−Cl bond in the C 2 B 10 systems. The chloro group in these complexes can be substituted by other moieties, leading to the isolation of [ η 6 -{ μ -1,2-[ o -C 6 H 4 (CH 2 ) 2 ]-1,2-C 2 B 10 H 10 }]Nd[( μ -H) 3 BH](THF) 3 ( 8 ) and [ η 6 -{ μ -1,2-[ o -C 6 H 4 (CH 2 ) 2 ]-1,2-C 2 B 10 H 10 }]Y( η 5 -C 5 H 5 )(THF) ( 9 ), respectively. Reduction of 6 or 7 with excess Li metal afforded the full-sandwich lanthanacarboranes { η 6 -[ μ -1,2-[ o -C 6 H 4 (CH 2 ) 2 ]-1,2-C 2 B 10 H 10 ] 2 Ln}{Li 5 (THF) 10 } (Ln = Er ( 11 ), Y ( 12 )). Treatment of 6 with excess Na metal generated the full-sandwich lanthanacarborane cluster [{ η 6 -[ μ -1,2-[ o -C 6 H 4 (CH 2 ) 2 ]-1,2-C 2 B 10 H 10 ] 2 Er}{Na 5 (THF) 6 }] 4 ( 13 ). These full-sandwich complexes were also prepared from the reaction of [{ μ -1,2-[ o -C 6 H 4 (CH 2 ) 2 ]-1,2-C 2 B 10 H 10 }Li 4 (THF) 6 ] 2 ( 3 ) with LnCl 3 . Their Gd analogue { η 6 -[ μ -1,2-[ o -C 6 H 4 (CH 2 ) 2 ]-1,2-C 2 B 10 H 10 ] 2 Gd}{Li 5 (THF) 9 } ( 10 ) was prepared via a “one-pot” interaction between μ -1,2-[ o -C 6 H 4 (CH 2 ) 2 ]-1,2-C 2 B 10 H 10 ( 1 ), excess Li metal, and GdCl 3 . All complexes were fully characterized by various spectroscopic data and elemental analyses. Complexes 4, 6, 8, 10, 11, and 13 were subjected to single-crystal X-ray analyses.