Thermal transformations of B10H12(NH3)2, B10H12(C5H5N)2, and B10H12(C9H7N)2

Conclusions For B₁₀H₁₂L₂, where L=NH₃, C₅H₅N, or C₉H₇N, features of thermal transformations in the range 25–850°C and the composition of the pyrolysis products are determined. The latter are x-ray amorphous phases, containing nitride, carbide, boron carbide, boron, and carbon.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 11, pp. 2481–2484, November, 1988.     

Unexpectedly facile isomerisation of [7,10-Ph2-7,10-nido-C2B10H10]2- to [7,9-Ph2-7,9-nido-C2B10H10]2-

The 2e-reduction of 1,12-Ph2-1,12-closo-C(2)B(10)H(10) followed by oxidation or metallation gives products that arise from [7,9-Ph2-7,9-nido-C(2)B(10)H(10)](2-), formed by unexpectedly facile isomerisation of the kinetic 7,10-isomer: the 4,1,6-MC(2)B(10) compounds which result are progressively isomerised to 4,1,8- and 4,1,12-isomers for M = {CpCo} but to an equilibrium mixture of 4,1,8- and 4,1,12-isomers for M = {(arene)Ru}.     

The structures of MeP(C2B10H10)2CH2 and MeAs(C2B10H10)2, compounds containing o-carborane ring carbon atoms in the heterocycle

Conclusions Crystal and molecular structures have been determined for 1-methylphospha-2,3,5,6-bis-o-carboranocyclohexane and 1-methylarsa-2,3,4,5-bis-o-carboranocyclopentane.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 7, pp. 1523–1528, July, 1979.     

Interaction of closo-decaborate anion B10H 10 2− with iminium salts

The interaction of closo-decaborate anions with iminium salts, either formed in situ or introduced into the reaction as individual compounds, has been studied. The reaction leads to products with an exopolyhedral boron-nitrogen bond. The formation of compounds with exopolyhedral boron-chlorine and boron-carbon bonds is also possible. The crystal structures of [NMe₂(CH₂Cl)]₂B₁₀H₈ and 3-CH₃-2,8-[NMe₂(CH₂Cl)]₂-7-ClB₁₀H₆ have been studied.     

New chemistry of 1,2-closo-P2B10H10 and 1,2-closo-As2B10H10; in silico and gas electron diffraction structures, and new metalladiphospha- and metalladiarsaboranes

The molecular structures of 1,2-closo-P(2)B(10)H(10) (1) and 1,2-closo-As(2)B(10)H(10) (2) have been determined by gas electron diffraction and the results obtained compared with those from computation at the MP2/6-31G** level of theory. The level of agreement is good for 2 (root-mean-square [rms] misfit for As and B atoms 0.0297 ?) and very good for 1 (rms misfit for P and B atoms 0.0082 ?). In comparing the structures of 1 and 2 with that of 1,2-closo-C(2)B(10)H(12) (I) it is evident that expansion of the polyhedron from I to 1 to 2 is restricted only to the heteroatom vertices and the B(6) face to which these are bound. Following deboronation (at B3) and subsequent metallation, compounds 1 and 2 have been converted into the new metalladiheteroboranes 3-(η-C(9)H(7))-3,1,2-closo-CoAs(2)B(9)H(9) (4), 3-(η-C(10)H(14))-3,1,2-closo-RuAs(2)B(9)H(9) (5), 3-(η-C(5)H(5))-3,1,2-closo-CoP(2)B(9)H(9) (6), 3-(η-C(9)H(7))-3,1,2-closo-CoP(2)B(9)H(9) (7) and 3-(η-C(10)H(14))-3,1,2-closo-RuP(2)B(9)H(9) (8), the last three constituting the first examples of metalladiphosphaboranes. Together with the known compound 3-(η-C(5)H(5))-3,1,2-closo-CoAs(2)B(9)H(9) (3), compounds 4-8 have been analysed by NMR spectroscopy and (except for 8) single-crystal X-ray diffraction. The (11)B NMR spectra of analogous pairs of metalladiphosphaborane and metalladiarsaborane (6 and 3, 7 and 4, 8 and 5) reveal a consistently narrower (9-10 ppm) chemical shift range for the metalladiarsaboranes, the combined result of a deshielding of the lowest frequency resonance (B6) and an increased shielding of the highest frequency resonance (B8) via an antipodal effect. In crystallographic studies, compounds 3 and 5B (one of two crystallographically-independent molecules) suffer As/B disorder, but in both cases it was possible to refine distinct, ordered, components of the disorder, the first time this has been reported for metalladiarsaboranes. Moreover, whilst the Cp compounds 6 and 3 are disordered, their indenyl analogues 7 and 4 are either ordered or significantly less disordered, a consequence of both the reduced symmetry of an indenyl ligand compared to a Cp ligand and the preference of the former for a distinct conformation relative to the cage heteroatoms. Unexpectedly, whilst this conformation in the cobaltadiphosphaborane 7 is cis-staggered (similar to that previously established for the analogous cobaltadicarborane), in the cobaltadiarsaborane 4 the conformation is close to cis-eclipsed.     

Local electronic structure of dicarba-closo-dodecarboranes C2B10H12

We report nonresonant inelastic X-ray scattering (NRIXS) measurement of core-shell excitations from both B 1s and C 1s initial states in all three isomers of the dicarba-closo-dodecarboranes C2B10H12. First, these data yield an experimental determination of the angular-momentum-projected final local density of states (l-DOS). We find low-energy resonances with distinctive local s- or p-type character, providing a more complete experimental characterization of bond hybridization than is available from dipole-transition limited techniques, such as X-ray absorption spectroscopies. This analysis is supported by independent density functional theory and real-space full multiple scattering calculation of the l-DOS which yield a clear distinction between tangential and radial contributions. Second, we investigate the isomer sensitivity of the NRIXS signal and compare and contrast these results with prior electron energy loss spectroscopy measurements. This work establishes NRIXS as a valuable tool for borane chemistry, not only for the unique spectroscopic capabilities of the technique but also through its compatibility with future studies in solution or in high-pressure environments. In addition, this work also establishes the real-space full multiple scattering approach as a useful alternative to traditional approaches for excited states calculations of aromatic polyhedral boranes and related systems.     

Triple linking of the decaboranyl cluster. Structure of [(SMe2)2B10H10(B10H13)2] as determined by synchrotron X-ray diffraction analysis

In an attempt to find generic routes to multiple inter-cluster sigma-linking, mild thermolysis of [6,9-(SMe2)2-arachno-B10H12] 1 in inert hydrocarbon solution gives the tridecaboranyl species [6,9-(SMe2)2-arachno-B10H(10)-1,5-(6'-nido-B10H13)2] 3 (23%).     

Theoretical study of isoelectronic molecules: B6H10, 2-CB5H9, 2,3-C2B4H8, 2,3,4-C3B3H7, and 2,3,4,5-C4B2H6

Isoelectronic molecules regarding B6H10, 2-CB5H9, 2,3-C2B4H8, 2,3,4-C3B3H7, and 2,3,4,5-C4B2H6 are studied by the density functional B3LYP/6-311G(d,p) method and the electron propagator theory in the partial third-order quasiparticale approximation, as well as the extrapolated calculation with the coupled-cluster CCSD(T) theory. The calculated ionization potentials are in good agreement with the experimental data from photoelectron spectroscopy. Valence structures are characterized with natural orbital bond (NBO) theory, exhibiting the multiple three-center two-electron bonds B-H-B, B-B-B, C-B-B, B-C-B, and C-B-C, and chemical bond rearrangements in the cations.     

Electrophilic substitution in eleven-vertex metallacarborane 1,2,4-CpCoC2B8H10

Bromination and mercuration of cobaltacarborane 1,2,4-CpCoC₂B₈H₁₀ were investigated. Mercuration under mild conditions (Hg(OCOCF₃)₂ in CH₂Cl₂) afforded the only monomercurated complex containing the mercury atom at position 6. Bromination gave rise to 3-mono-, 6-mono-, or 6,9-disubstituted derivatives depending on the reaction conditions. The mercurated derivative was studied by the X-ray diffraction method.