Significant advantages result from combining the disparate hydrogen release pathways for ammonia-borane (AB) dehydrogenation using ionic liquids (ILs) and transition metal catalysts. With the RuCl(2)(PMe(3))(4) catalyst precursor, AB dehydrogenation selectivity and extent are maximized in an IL with a moderately coordinating ethylsulfate anion.

The syntheses and structural characterizations of the first extensive series of Group 9 (Co, Rh, and Ir) tricarbadecaboranyl halfsandwich complexes are reported. The carbonyl complexes 1,1-(CO) 2 -2-Ph-closo-1,2,3,4-MC 3 B 7 H 9 , M = Co (1), Rh (2), and 8,8,8-(CO) 3 -9-Phnido-8,7,9,10-IrC 3 B 7 H 9 (3) were obtained by the reactions of Li + (6-Phnido-5,6,9-C 3 B 7 H 9 ) − with Co(CO) 4 I, [Rh(CO) 2 Cl] 2 , and Ir(CO) 3 Cl, respectively. Further reactions of 1, 2, and 3 with 1,2-bis(diphenylphosphino)ethane (dppe) yielded the 1,1-dppe-2-Ph-closo-1,2,3,4-MC 3 B 7 H 9 , M = Co (4), Rh (5), and 8-CO-8,8-dppe-9-Ph-nido-8,7,9,10-IrC 3 B 7 H 9 (6) derivatives with their crystallographic determinations showing that 1 and 2 contain the η 6 -2-Ph-2,3,4-C 3 B 7 H 9 1− ligand with the metallatricarbadecaboranyl cluster fragments having closo-octadecahedral geometries, while 3 has a slipped-cage η 4 -9-Ph-7,9,10-C 3 B 7 H 9 1− coordination and a nido-cluster framework. The reaction of Li + (6-Ph-nido-5,6,9-C 3 B 7 H 9 ) − with [Rh(COD)Cl] 2 and [Ir(COD)Cl] 2 produced the COD coordinated complexes 1,1-COD-2-Ph-closo-1,2,3,4-MC 3 B 7 H 9 , M = Rh (7), Ir (8), with η 6 -2-Ph-2,3,4-C 3 B 7 H 9 1− ligands and closo-cluster structures. On the other hand, slipped-cage structures with η 4 -9-Ph-7,9,10-C 3 B 7 H 9 1− coordination were achieved by the reactions of 1, 3, or 8 with an excess of the stronger donor tert-butyl isocyanide to give 8,8,8-(CN t Bu) 3 -9-Ph-nido-8,7,9,10-MC 3 B 7 H 9 , M = Co (9), Ir (10), respectively, or by the reaction of 8 with 1 equiv of tert-butyl isocyanide to give 8,8-COD-8-CN t Bu-9-Ph-nido-8,7,9,10-IrC 3 B 7 H 9 (11). Upon the reaction of 1 with diphenylacetylene, both carbonyls were displaced with subsequent alkyne cyclization to form the tetraphenylcyclobutadienyl complex 1,1-(η 4 -C 4 Ph 4 )-2-Ph-closo-1,2,3,4-CoC 3 B 7 H 9 (12). The crystalline tetramethylcyclobutadienyl derivative 1,1-(η 4 -C 4 Me 4 )-2-Ph-closo-1,2,3,4-CoC 3 B 7 H 9 (13) was synthesized by the reaction of Li + (6-Ph-nido-5,6,9-C 3 B 7 H 9 ) − with (η 4 -C 4 Me 4 )Co(CO) 2 I, and its crystallographic determination confirmed the formation of a complex where a formal Co 3+ ion is sandwiched between η 4 -C 4 Me 4 2− and η 6 -2-Ph-2,3,4-C 3 B 7 H 9 1− ligands.In contrast to the reactions with diphenylacetylene, the reaction of 8 with 3-hexyne resulted in cage deboronation to produce 2,2-COD-10-Ph-closo-2,1,6,10-C 3 B 6 H 8 (14). Neither 7 nor 8 would undergo oxidativeaddition when treated with I 2 . Although 11 reacted with I 2 and perfluoro-1-iodohexane, oxidative-addition products were also not obtained, but instead, iodation of a cage boron occurred to produce 8,8-COD-1-CN t Bu-9-Ph-11-I-nido-8,7,9,10-IrC 3 B 7 H 8 (15).

In contrast to previous reactions carried out in cyclopentane solvent at room temperature that produced 6-TfO-B10H13 (TfO = CF3SO3), the reaction of closo-B10H10(2-) with a large excess of trifluoromethanesulfonic acid in the ionic liquid 1-butyl-3-methylimidazolium trifluoromethanesulfonate (bmimOTf) gave exclusively the previously unknown 5-TfO-B10H13 isomer. Experimental and computational studies demonstrated that the difference in the products of the two reactions is a result of 6-TfO-B10H13 isomerizing to 5-TfO-B10H13 above room temperature in bmimOTf solutions. Reactivity studies showed that 5-TfO-B10H13: (1) is deprotonated by reaction with 1,8-bis(dimethylamino)naphthalene to form the 5-TfO-B10H12(1-) anion; (2) reacts with alcohols to produce 6-RO-B10H13 boryl ethers (R = Me and 4-CH3O-C6H4); (3) undergoes olefin-hydroboration reactions to form 5-TfO-6,9-R2-B10H11 derivatives; and (4) forms a 5-TfO-6,9-(Me2S)2-B10H11 adduct at its Lewis acidic 6,9-borons upon reaction with dimethylsulfide. The 5-TfO-6,9-(Me2S)2-B10H11 adduct was also found to undergo alkyne-insertion reactions to form a range of previously unreported triflate-substituted 4-TfO-ortho-carboranes (1-R-4-TfO-1,2-C2B10H10) and reactions with triethylamine or ammonia to form the first TfO-substituted decaborate [R3NH(+)]2[2-TfO-B10H9(2-)], and [R3NH(+)]2[1-TfO-B10H9(2-)] (R = H, Et) salts.