Toward unidirectional rotary motion in nickelacarboranes: characterization of diastereomeric nickel bis(dicarbollide) complexes derived from the [nido-7-CH3-7,8-C2B9H11]- anion.
Two diastereomeric pairs of nickel bis(C-monomethyldicarbollide) complexes, derived from the racemic [nido-7-CH(3)-7,8-C(2)B(9)H(11)](-) anion, have been synthesized and characterized by NMR spectroscopy and single-crystal X-ray diffraction analysis. Neutral (dd/ll) [1(2),1'(2')-Me(2)-closo-3,1,2-Ni(IV)C(2)B(9)H(10)-{3:3'}-closo-3',1',2'-Ni(IV)C(2)B(9)H(10)] 1 and (meso) [1,2'-Me(2)-closo-3,1,2-Ni(IV)C(2)B(9)H(10)-{3:3'}-closo-3',1',2'-Ni(IV)C(2)B(9)H(10)] 2 adopt typical cisoid conformations in the solid state. The temperature-dependent (11)B and (1)H NMR spectra of 2 indicate that the energy barrier to the interconversion of racemic rotational isomers is 66.5 +/- 2 kJ/mol. In the solid state, the [NMe(4)](+) salts of the (dd/ll) [1(2),1'(2')-Me(2)-closo-3,1,2-Ni(III)C(2)B(9)H(10)-{3:3'}-closo-3',1',2'-Ni(III)C(2)B(9)H(10)](-) anion NMe(4) x 3 and the (meso) [1,2'-Me(2)-closo-3,1,2-Ni(III)C(2)B(9)H(10)-{3:3'}-closo-3',1',2'-Ni(III)C(2)B(9)H(10)](-) anion NMe(4) x 4 adopt gauche and transoid configurations, respectively, with transoid methyl substituents in both cases.
Department of Chemistry and Biochemistry, University of California at Los Angeles, 607 Charles E. Young Drive (East), Los Angeles, California 90095, USA.
Robert D
RD
Kennedy
Carolyn B
CB
Knobler
M Frederick
MF
Hawthorne