Structural characterization and cage-condensation reactions of the coupled-cage borane 1:2'-[B5H8]2: new routes to higher single-cage boranes and carboranes

Abstract

Rh-S-H are -14.5°in 2). Thus, the hydrogens linked to one metal and to one sulfur remain in close proximity.A CH2C12 solution of 2 under a stream of argon loses 2 mol of H2 (as determined by GC) and transforms into [(triphos)Rh-(M-S)2Rh(triphos)](BPh4)2 (3) (31P|'H| NMR (CD3COCD3, 293 K) 24.02 ppm (/(P-Rh) = 102 Hz, doublet, triphos)). Brown crystals are precipitated by addition of ethanol. A stream of H2 turns a solution of 3 to the original pink color, and the complex 2 is obtained quantitatively in 4 h. A preliminary X-ray analysis on 3 has confirmed the structural formulation given in Scheme I.The ability of 3 to activate homodinuclear molecules shows up in the reaction with oxygen. When 02 is bubbled throughout a CH2C12 solution of 3, red crystals of the µ-SO complex [(triphos)Rh(/u-SO)2Rh(triphos)](BPh4)2 (4) are obtained quantitatively. The crystal structure and characterization of 4, prepared by a different synthetic strategy, have recently been reported by (3) Ghilardi, C.

Click Dehydrogenation of Carbon-Substituted nido-5,6-C2B8H12 Carboranes: A General Route to closo-1,2-C2B8H10 Derivatives

“…The closo-1,2-C 2 B 8 H 10 (2a) carborane, a 10-vertex analogue of the popular o-carborane, was first isolated by Rietz and Schaeffer in 1973, 1 together with its C,C-dimethyl derivative, as a side product from reactions between R 2 C 2 (R = H and Me) alkynes and the hardly available boranes n-B 9 H 15 and B 8 H 12 . The synthesis of 2a 2 and that of its 1,2-Me 2 derivative 3 from other borane 4 and carborane 2 resources were also reported later by other authors, and the structure of 2a was determined by electron diffraction. 5 The 1,2-Ph 2 derivative was also isolated as a side product from the reaction between 4-Me 2 SB 9 H 13 and Ph 2 C 2 .…”

Computational Studies of Nido-8-Vertex Boranes, Carboranes, Heteroboranes, and the Lewis Base Adduct nido-B8H10L

“…B 8 H 10 ·L. Another nido-8-vertex electron-count cluster known experimentally is nido -B 8 H 10 ·L (where L = NEt 3 ), which was characterized by NMR spectroscopy. The originally proposed static structure ( 16 , Figure a) has a ni-8〈V〉 configuration with the Lewis base at the unique boron of the open face.…”

Unusual Closure of the Ten-Vertex Nido Cage via Alkylation: Regiospecific Synthesis of 3-Alkyl Derivatives of closo-1,2-C2B8H10

“…For 4a: m/z (max) calcd 135.17, found 135. 16 (10 mL) was treated with a 2fold excess of sodium hydride (50 mg) under stirring at room temperature. After the hydrogen evolution had ceased, the supernatant NaH was removed by vacuum filtration.…”

“…Despite numerous reports − on the synthesis, reactions and structure of the closo -1,2-R 2 C 2 B 8 H 8 dicarbarboranes, 10-vertex analogs of the popular o -carborane, only the methylation at the C-vertexes via standard LiBu/MeI method and electrophilic halogenation at B9 and B10 sites have been published; no other reports on reactions leading to direct substitution of the carborane cage in compounds 1 have so far been available.…”