TY - JOUR
T1 - The synthesis and molecular and crystal structures of 1-methyl-2-carboxy-1, 2-dicarba-closo-dodecaborane(12), 1-phenyl-2-carboxy-1,2-dicarba-closo- dodecaborane(12) and 1-phenyl-2-benzoyl-1,2-dicarba-closo-dodecaborane(12)
AU - Venkatasubramanian, Ulaganathan
AU - Donohoe, David J.
AU - Ellis, David
AU - Giles, Barry T.
AU - MacGregor, Stuart A.
AU - Robertson, Susan
AU - Rosair, Georgina M.
AU - Welch, Alan J.
AU - Batsanov, Andrei S.
AU - Boyd, Lynn A.
AU - Copley, R. C B
AU - Fox, Mark A.
AU - Howard, J. A K
AU - Wade, Kenneth
PY - 2004/2/12
Y1 - 2004/2/12
N2 - The structures of 1-Me-2-COOH-1,2-closo-C2B10H 10 (1), 1-Ph-2-COOH-1,2-closo-C2B10H 10 (2) and 1-Ph-2-COPh-1,2-closo-C2B10H 10 (3) have been determined by X-ray crystallography. In 1 the orientation of the COOH group is defined by ?COOH=65.0(2) syn°, and this group H-bonds to that in a second molecule via a centrosymmetric eight-membered ring, R22(8). DFT calculations on the parent species 1-COOH-1,2-closo-C2B 10H11 reveal that the structure with ? COOH=90syn°is preferred, with a barrier to COOH rotation of ˜17 kJmol-1. Similar calculations on 1 yield a lower rotational barrier, ˜7 kJmol-1, because internal H-bonding is now denied. In compound 2 the COOH group is twisted to lower ? values [5.0(3)°and 39.7(3)°] but both crystallographically independent molecules exist as dimers in the solid state by virtue of R22(8) rings. Compound 2 crystallises from wet solvent as a monohydrate, the structure of which reveals a non-planar centrosymmetric R 44(12) ring and near-orthogonal Ph and COOH substituents [?Ph=6.7(2) and ?COOH=78.0(2) syn°]. In compound 3 molecular association by H-bonding is blocked, so 3 serves as a useful comparative structure for 2. © 2003 Elsevier Ltd. All rights reserved.
AB - The structures of 1-Me-2-COOH-1,2-closo-C2B10H 10 (1), 1-Ph-2-COOH-1,2-closo-C2B10H 10 (2) and 1-Ph-2-COPh-1,2-closo-C2B10H 10 (3) have been determined by X-ray crystallography. In 1 the orientation of the COOH group is defined by ?COOH=65.0(2) syn°, and this group H-bonds to that in a second molecule via a centrosymmetric eight-membered ring, R22(8). DFT calculations on the parent species 1-COOH-1,2-closo-C2B 10H11 reveal that the structure with ? COOH=90syn°is preferred, with a barrier to COOH rotation of ˜17 kJmol-1. Similar calculations on 1 yield a lower rotational barrier, ˜7 kJmol-1, because internal H-bonding is now denied. In compound 2 the COOH group is twisted to lower ? values [5.0(3)°and 39.7(3)°] but both crystallographically independent molecules exist as dimers in the solid state by virtue of R22(8) rings. Compound 2 crystallises from wet solvent as a monohydrate, the structure of which reveals a non-planar centrosymmetric R 44(12) ring and near-orthogonal Ph and COOH substituents [?Ph=6.7(2) and ?COOH=78.0(2) syn°]. In compound 3 molecular association by H-bonding is blocked, so 3 serves as a useful comparative structure for 2. © 2003 Elsevier Ltd. All rights reserved.
KW - Carborane
KW - DFT calculations
KW - Spectroscopy
KW - X-ray crystallography
UR - http://www.scopus.com/inward/record.url?scp=10744221329&partnerID=8YFLogxK
U2 - 10.1016/j.poly.2003.10.016
DO - 10.1016/j.poly.2003.10.016
M3 - Article
SN - 0277-5387
VL - 23
SP - 629
EP - 636
JO - Polyhedron
JF - Polyhedron
IS - 4
ER -