o-Carboranylcarbene and m-carboranylcarbene

Chari, Sarangan; Chiang, Sheau-Hwa; Jones, Maitland

doi:10.1021/ja00375a033

Cited by 23 publications

(10 citation statements)

References 2 publications

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“…The icosahedral carboranes, o-, m-, and p-dicarba-c/oso-dodecaborane(12) (C2B10H12) have attracted industrial attention because of their potential use in high-temperature resistant coatings and as precursors to ceramic materials such as B4C. 2 The ortho isomer, o-C2B10H12, is an orientationally disordered solid at amo-Carborane (1) (2) Obenland, C. O.; Papetti, S. U.S. Patent 3509216, 1970. bient temperature and pressure, and its structural properties have been studied by X-ray diffraction,3,4 differential scanning and adiabatic calorimetry,3,5 and variable-temperature (300-11 K) IR,6'8 Raman,9'11 and *H and nB NMR spectroscopies.12'14 While there is general agreement that an order-disorder phase transition exists for o-carborane at ~270 K, some authors have also reported other phase transitions occurring at lower temperatures, but these claims have been disputed.10,11 It is clear, (3) Baughmann, R. H. J. Chem. Phys.…”

Section: Introductionmentioning

confidence: 99%

“…(14) Reynhardt, E. C.; Watton, A. however, that the structure of this plastically crystalline material is extremely sensitive to its thermal history, regardless of the analytical technique employed. The application of high pressure often produces the same structural changes in a sample that occur upon lowering the temperature.15 Also, although several research groups have apparently examined the variable-temperature IR spectra of o-carborane, surprisingly, only spectral data for the v(BH) region have been reported.6"8 For these reasons, we have now investigated the phase-transition behavior of o-C2B|0Hl2: (1) under high external pressures by using a recently developed micro-Raman spectroscopic technique16 and (2) by variable-temperature FT-IR spectroscopy.…”

Section: Introductionmentioning

confidence: 99%

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Variable-temperature and -pressure vibrational spectra of o-carborane

Paroli¹,

Kawai²,

Lord³

et al. 1989

Inorg. Chem.

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efg tensor exactly coincide with the molecular coordinate system of Figure 1. In the more detailed SCCEHMO calculations they almost coincide.The absolute values of calculated quadrupole splittings for the [II,II] and [II,III] ions are in very good agreement with the observed data (Table III). We notice that the largest efg component is still Vyy, i.e. the component within the pyrazine plane perpendicular to the Ru-N(bridge) direction. The sign of the efg cannot be determined from powder spectra unless the triplet structure of the two components of the spectrum is resolved or, at least, manifests itself in visible asymmetries of the pattern. Such asymmetries begin to become noticeable when the splitting A of the excited state exceeds about 0.5 mm s'1. For [II,II] it is impossible to even guess the sign, while the [II,III] and [III,III] species are just at the limit where the sign of Vyy should become detectable. Owing to additional complications such as axially nonsymmetric efg tensors, unknown preferred orientation of the crystallites in the sample, and anisotropies of the Debye-Waller factor, we have to refrain from drawing any conclusions about

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Variable-temperature and -pressure vibrational spectra of o-carborane

Paroli¹,

Kawai²,

Lord³

et al. 1989

Inorg. Chem.

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“…With the methyl groups syn, favorable interactions overwhelm the steric problem. When charge dispersal in not present, as in carboranylcarbenes, the steric factors prevail …”

Section: Resultsmentioning

confidence: 99%

2-Biphenylenylcarbene¹

Wu¹,

Jones²,

WALTON³

et al. 1998

J. Org. Chem.

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“…The carboranes as an important class in inorganic chemistry are extensively used in coordination compounds [14][15][16][17][18], inorganic pharmaceuticals and biological systems, radiopharmaceuticals [19], polymers [20][21][22] as well as in neutron capture therapy [23]. CB 4 H 8 is a carborane that has a square pyramidal structure, the carbon atom is located in the apex of pyramid and the boron http HOX (X = F, Cl, Br and I).…”

Section: Introductionmentioning

confidence: 99%