title: An Ab Initio Study of the Structures and Selected Properties of 1,2-Dihydro-1,2-azaborine and Related Molecules.
abstract: An ab initio study has been carried out to investigate the effect of replacing [HC-CH]n linkages in benzene by the isoelectronic [HN-BH]n linkages for n = 1, 2, and 3. Such replacements give rise to azaborine, a set of diazaborines, borazine, and pseudoborazine. These replacements lead to significant rearrangements of electron densities in these molecules due primarily to the introduction of the polar B-N bond. As a result, azaborine and diazaborines exhibit much more localized structures than that of benzene. They are also less aromatic than benzene but have a higher degree of aromaticity than borazine. The bonding patterns can be related to the relative stabilities of the diazaborines. Among these molecules, the most stable isomer contains an N-B-N-B linkage, while the two least stable isomers have either a B-B or a N-N bond. Changes in bonding patterns are also reflected in changes in the N1-B2 coupling constant. When N1 and B2 are bonded to the less electronegative atoms C and B, (1)J(N1-B2) increases relative to borazine, but when either N1 or B2 is bonded to N, (1)J(N1-B2) decreases. Computed NMR chemical shifts and coupling constants are in good agreement with available experimental data.
authors.affiliation: Department of Chemistry, Youngstown State University, One University Plaza, Youngstown, Ohio 44555, Departamento de Química, C-9, Universidad Autónoma de Madrid, Cantoblanco, E-28049 Madrid, Spain, and Instituto de Química Médica, Consejo Superior de Investigaciones Cientfícas, Juan de la Cierva, 3, E-28006 Madrid, Spain.
authors.forename: Janet E
authors.initials: JE
authors.lastname: Del Bene
authors.affiliation: Department of Chemistry, Youngstown State University, One University Plaza, Youngstown, Ohio 44555, Departamento de Química, C-9, Universidad Autónoma de Madrid, Cantoblanco, E-28049 Madrid, Spain, and Instituto de Química Médica, Consejo Superior de Investigaciones Cientfícas, Juan de la Cierva, 3, E-28006 Madrid, Spain.
authors.forename: Manuel
authors.initials: M
authors.lastname: Yáñez
authors.affiliation: Department of Chemistry, Youngstown State University, One University Plaza, Youngstown, Ohio 44555, Departamento de Química, C-9, Universidad Autónoma de Madrid, Cantoblanco, E-28049 Madrid, Spain, and Instituto de Química Médica, Consejo Superior de Investigaciones Cientfícas, Juan de la Cierva, 3, E-28006 Madrid, Spain.
authors.forename: Ibon
authors.initials: I
authors.lastname: Alkorta
authors.affiliation: Department of Chemistry, Youngstown State University, One University Plaza, Youngstown, Ohio 44555, Departamento de Química, C-9, Universidad Autónoma de Madrid, Cantoblanco, E-28049 Madrid, Spain, and Instituto de Química Médica, Consejo Superior de Investigaciones Cientfícas, Juan de la Cierva, 3, E-28006 Madrid, Spain.
authors.forename: José
authors.initials: J
authors.lastname: Elguero