691378-72-0Relevant academic research and scientific papers
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)
Venkatasubramanian, Ulaganathan,Donohoe, David J.,Ellis, David,Giles, Barry T.,MacGregor, Stuart A.,Robertson, Susan,Rosair, Georgina M.,Welch, Alan J.,Batsanov, Andrei S.,Boyd, Lynn A.,Copley, Royston C.B.,Fox, Mark A.,Howard, Judith A.K.,Wade, Kenneth
, p. 629 - 636 (2004)
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 θCOOH=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 θ 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 θ values [5.0(3)°and 39.7(3)°] but both crystallographically independent molecules exist as dimers in the solid state by virtue of R2 2(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 [θPh=6.7(2) and θCOOH=78.0(2) syn°]. In compound 3 molecular association by H-bonding is blocked, so 3 serves as a useful comparative structure for 2.
