Matrix isolation study of the reaction of diborane with methanol: spectroscopic characterization of methoxyborane, H2B=OCH3

Carpenter, John D.; Ault, Bruce S.

doi:10.1021/j100190a035

Cited by 15 publications

(11 citation statements)

References 4 publications

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“…This complexation energy is about half of the dimerization energy (34.4 kcal/mol) of BH3 for diborane included two B--B bridged bonds. That is to say, the complexation energy in 5 corresponds to one B--B bridged bond energy. The mechanism for the formation of the complex 5 through TS1 is similar to that for the reaction of the Menschutkin17 Snz type.…”

Section: Resultsmentioning

confidence: 99%

Ab Initio Molecular Orbital Study of the Chemical Reactions of Diborane with Ammonia

Sakai¹

1995

J. Phys. Chem.

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The potential energy surface for the reaction of diborane B2H6 with ammonia has been calculated by MP4/ 6-3 1 I+G(d,p)//MP2/6-3 lG(d,p) method with zero-point energy corrections. Two steps for the formation of aminoborane, HzB=NH2 were studied. The first step is the formation of borane-ammonia adduct H,B: NH3 and complex H3BHBH2NH3, and the second is three type (1,l-, 1,2-, and 1,3-) subsequent hydrogen eliminations. The adduct H3B:NH3 formation occurs via the dissociation (BH3 + BH3) of diborane or via the complex H3BHBHzNH3 formation. Two transition states for the complex H3BHBH2NH3 formation from diborane and ammonia were found, which are an ionic and a covalent (keeping of one B-H-B bridge bond) types. The transition state of the covalent type is about 5 kcal/mol lower in energy than that of the ionic one. For 1,l-hydrogen elimination, two eliminations from B atom and from N atom of H3B:NH3 are examined. The energy barriers for both eliminations are extremely high (107-103 kcal/mol from the isolated diborane and ammonia). For 1,2-hydrogen elimination, four reaction paths were calculated. These reaction paths have also high energy barriers (33-46 kcal/mol), since essentially they are forbidden reactions by the Woodward-Hoffmann rules. The reaction pathway of 1,3-hydrogen elimination includes two concerted reactions (hydrogen elimination and hydrogen shift), which have a low energy barrier of 16.7 kcal/mol at the MP4/6-31 l+G(d,p) + ZPE level. Two elimination pathways (1,Zhydrogen elimination from the adduct and 1,3-hydrogen elimination from the complex) lead to aminoborane in one step, except for 1,l-hydrogen elimination with extremely high barrier.

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Section: Resultsmentioning

confidence: 99%

Ab Initio Molecular Orbital Study of the Chemical Reactions of Diborane with Ammonia

Sakai¹

1995

J. Phys. Chem.

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“…Diborane (B 2 H 6 ) chemistry has long been a very active field of research as a consequence of its unusual structure and bonding. − It reacts readily with a range of Lewis bases, in both solution and gas phase. Recently, a series of papers appeared on the pyrolysis of the diborane with NH 3 , PH 3 , SH 2 , CH 3 NH 2 , CH 3 OH, and CH 3 SH, leading to selective formation of aminoborane, phosphinoborane, mercaptoborane, methylaminoborane, methoxyborane, and methylmercaptoborane, respectively. It was concluded from these results that aminoborane, phosphinoborane, and mercaptoborane were produced through borane−Lewis base adducts.…”

Section: Introductionmentioning

confidence: 99%

Stability of Borane−Adduct Complexes: A G-2 Molecular Orbital Study

1997

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Complexation energies of H3BXH n and [H3BXH n - 1]- complexes (X = N, O, F, P, S, and Cl) (n = 3, 2, 1) have been computed at the G-2 level of theory. The formation of H3BXH3 (X = N, P) is found to be more favored than the formations of H3BXH2 (X = O, S) and H3BXH (X = F, Cl). The qualitative features of the molecular orbital interaction (the correlation diagrams) of H3BNH3 (C 3 v symmetry group), H3BOH2 (C s symmetry group), and H3BFH (C s symmetry group) complexes are presented. These diagrams show that the σ character of the B−X bond decreases and the π character increases when the electronegativity of X increases and indicate that the B−X bond cannot be treated only in terms of the simplest model of the HOMO−LUMO interaction (i.e., a two-level and two-electron model system). Two linear correlations were established and discussed. The first one was between proton affinities of the Lewis bases L (L = XH n and [XH n - 1]-, n = 3, 2, 1) and complexation energies of the H3BL compounds calculated at the G-2 level of theory. The second correlation was between the 11B NMR coupling constant 1 J B - H and the complexation energies of H3BL (L = OH-, PH2 - , SH-, Cl-, NH3, and PH3).

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“…Carpenter and Ault studied the reaction of B 2 H 6 with CH 3 OH with the merged-jet copyrolysis of Ar/B 2 H 6 and Ar/CH 3 -OH followed by trapping on a low-temperature window. They isolated and characterized methoxyborane, H 2 BOCH 3 and proposed the mechanism given in eq 6. …”

Section: Introductionmentioning

confidence: 99%

Ab Initio Study of Diborane Hydrolysis

McKee

1996

J. Phys. Chem.

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Ab initio calculations have been applied to the mechanism of diborane hydrolysis in the gas phase. In the first step, water adds to diborane to form a complex which eliminates H 2 in a concerted step to form BH 3 , H 2 , and H 2 BOH. The subsequent steps to the formation of the ultimate product, B(OH) 3 , can take place via two alternative pathways. In the first pathway, H 2 BOH can form a complex with H 2 O which eliminates H 2 to form HB(OH) 2 , followed by addition of another molecule of H 2 O and elimination of another H 2 . Alternatively, two molecules of H 2 BOH can associate to form a dimer which dissociates to form BH 3 plus HB(OH) 2 . Likewise, the association/dissociation of H 2 BOH/HB(OH) 2 to BH 3 /B(OH) 3 completes the transformation. Thus, in the second pathway, H 2 BOH comes exclusively from the first step while the hydrolysis product is due to equilibrium steps driven by the greater thermodynamic stability of products.

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Matrix isolation study of the reaction of diborane with methanol: spectroscopic characterization of methoxyborane, H2B=OCH3

Cited by 15 publications

References 4 publications

Ab Initio Molecular Orbital Study of the Chemical Reactions of Diborane with Ammonia

Ab Initio Molecular Orbital Study of the Chemical Reactions of Diborane with Ammonia

Stability of Borane−Adduct Complexes: A G-2 Molecular Orbital Study

Ab Initio Study of Diborane Hydrolysis

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