RESOLUTION OF THE [6,6'-MU-(CH3)(2)P-(1,7-(C2B9H10)(2))-2-CO] BRIDGEDCOBALTACARBORANE TO ENANTIOMERS PURE BY CHIRAL HPLC, CIRCULAR-DICHROISM SPECTRA AND ABSOLUTE-CONFIGURATIONS BY X-RAY-DIFFRACTION

Racemic [6,6'-mu-(CH3)(2)P-(1,7-(C2B9H10)(2))-2-Co] zwitterion 1R was resolved into enantiomers 1A and 1B by chiral HPLC, and, for the first time for a chiral metallacarborane, absolute configurations of both e nantiomers were determined by X-ray diffraction. HPLC results, circula r dichroism spectra and crystallographic data [orthorhombic, space gro up P2(1)2(1)2, Z=8; 1A: a=11.5180(5) Angstrom, b=12.4741(6) Angstrom, c=13.8335(8) Angstrom, V=1987.6(2) Angstrom(3), 1B: a=11.5177(3) Angst rom, b=12.4700 Angstrom, c=13.8326(6) degrees, V=1986.7(1) Angstrom(3) ] are presented. Nomenclature and correlation of the CD curves with th ose reported earlier for closely related analogs, are discussed, along with general implications for chiral HPLC resolutions on a beta-cyclo dextrin column. (C) 1998 Elsevier Science Ltd. All rights reserved.