Synthesis, structure, and reactivity of organolanthanide carboranyl compounds and lanthanacarboranes derived from a versatile ligand, Me2C(C5H5)(C2B10H11)

The compound Me2C(C5H5)(C2B10H11) (I) could be conveniently converted into the monoanion [Me2C(C5H4)(C2B10H11)]- (I-1) and the dianion [Me2C(C5H4)(C2B10H10)](2-) (I-2) by treatment with excess NaH and 2 equiv of n-BuLi, respectively. The monoanion I-1 could be further converted into the trianion [Me2C(C5H4)(nido-C2B10H11)](3-) (I-3) by reaction with 2 equiv of Na metal in THF and into the pentaanion [Me2C(C5H4)(arachno-C2B10H11)](5-) in the presence of LnCl(3) and excess Na metal in THF. Reactions of LnCl(3) with the monoanion I-1 in molar ratios of 1:1, 1:2, and 1:3 generated the mono-, bis-, and tris-ligated organolanthanide compounds [eta(5)-Me2C(C5H4)(C2B10H11)]LnCl(2)(S)(n) ((S)(n) = (THF)(3), Ln = Er (1), Sm (2); (S)(n) = (DME)(2), Ln = Nd (3)), [eta(5)-Me2C(C5H4)(C2B10H11)](2)SmCl(THF)(2) (4), and [eta(5)-Me2C(C5H4)-(C2B(10)H(11))](3)Sm . 0.5C(7)H(8) (5), respectively. Reaction of LnCl(3) with 1 or 2 equiv of the dianion I-2 gave the same compound, [{eta(5):sigma-Me2C(C5H4)(C2B10H10)}(2)Ln][Li(DME)(3)] (Ln = Sm (6), Yb (7)). 6 could also be prepared by treatment of 2 with 1 equiv of the dianion I-2. Reaction of YbI2 with 1 equiv of 1-2, followed by treatment with 1 equiv of I-1, also gave compound 7. However, YbI2 reacted with 2 equiv of I-1 to afford the organoytterbium(II) compound [eta(5)-Me2C(C5H4)(C2B10H11)](2)Yb(THF)(2) (8). Interaction of SmI2 with 2 equiv of I-1 yielded two compounds, the redox product [eta(5):eta(6)-Me2C(C5H4)(C2B10H11)]Sm(THF)(2) (9) and the tris-ligated compound 5. The compound [eta(5):eta(6)-Me2C( C5H4)(C2B10H11)]Er(THF)(2) (10), an analogue of 9, was prepared by treatment of 1 with 2 equiv of Na metal or by reaction of ErCl3 with 1 equiv of I-3. Treatment of 10 with excess Na metal gave the first organolanthanide compound containing a eta(7)-carboranyl ligand, [{[eta(5):eta(7)-Me2C(C5H4)(C2B10H11)]Er}(2){Na-4(THF)(9)}](n) (11). Its Dy analogue, [{[eta(5):eta(7)-Me2C(C5H4)(C2B10H11)]Dy}(2){Na-4(THF)(9)}](n) (12), could also be prepared by a "one-pot" reaction of DyCl3, I-1, and excess Na metal. Treatment of 11 with 2 equiv of ErCl3 in THF gave the novel tetranuclear cluster [{eta(5):eta(7)-Me2C(C5H4)(C2B10H11)}Er-2(mu-Cl)-(THF)(3)](2) (13), in which the Er3+ ions replace all Na+ ions in 11. All of these compounds were fully characterized by various spectroscopic data and elemental analyses. The solid-state structures of compounds 4-11 and 13 have been confirmed by single-crystal X-ray analyses.