Issue title: Special Issue based on the Symposium: Main Group Chemistry: A Continual Source of Fundamental New Knowledge and Applications in Everyday Life; 67th Southwest Regional Meeting of the American Chemical Society Austin, TX, USA; November 9–12, 2011 Guest Editor: John C. Gordon
Article type: Research Article
Authors: Schubert, David M. | Knobler, Carolyn B. | Visi, Mandana Z.
Affiliations: R&D Department, U.S. Borax Inc., Rio Tinto Minerals, Greenwood Village, CO, USA | McCullough Crystallographic Laboratory, Department of Chemistry and Biochemistry, University of California at Los Angeles, Los Angeles, CA, USA
Note: [] Corresponding author: David M. Schubert, U.S. Borax Inc., Rio Tinto Minerals, 8051 E. Maplewood Ave., Greenwood Village, CO 80111, USA. Tel.: +1 303 713 5226; E-mail: david.schubert@borax.com
Abstract: Reactions of 1,n-diaminoalkanes (n = 5, 6, 8) with excess boric acid in the absence of added solvent resulted in novel pentaborate derivatives containing N → B dative bonds. These diaminoalkane-pentaborate adducts include analogous zwitterions, B5O6(OH)4NH2(CH2)5NH3 (1) and B5O6(OH)4NH2(CH2)6NH3 (2) and the adduct salt [H3N(CH2)8NH3][B5O6(OH)4NH2(CH2)8NH2B5O6(OH)4]·2B(OH)3·2H2O (3). Compounds 1 and 2 form unusual zwitterion pairs, whereas 3 exhibits a large borate dianion comprised of two anionic pentaborate moieties tethered together by a doubly B-N bonded diaminooctane group. These compounds exhibit similar B-N bond lengths in the 1.622–1.638 Å range and nearly tetrahedral geometries around Lewis acceptor boron atoms. Compound 1 crystallized in the triclinic space group P-1 with a = 7.4366(17), b = 9.585(2), c = 11.116(3) Å, α = 71.046(2), β = 75.347(2), γ = 77.236(2)°, V = 716.6(3) Å3, Z = 2; 2 triclinic, P-1, a = 7.2376(5), b = 9.5921(6), c = 11.9329(7) Å, α = 71.694(2), β = 72.749(2), γ = 73.691(3)°, V = 734.86(8) Å3, Z = 2; and 3, triclinic, P-1, a = 8.9871(5), b = 10.1041(6), c = 13.6052(8) Å, a = 84.6160(10), β = 72.3950(10), γ = 65.3050(10)°, V = 1069.13(11) Å3, and Z = 1.
Keywords: Boron, borate, crystal structure, dative bond, coordinative covalent bond, tetrahedral character
DOI: 10.3233/MGC-2012-0062
Journal: Main Group Chemistry, vol. 11, no. 1, pp. 69-88, 2012
