Cluster and molecular mechanical analysis of the conformations of all six-membered cobalt(III) diamine rings in the Cambridge structure database

An agglomerative, single-link clustering method was used to separate all of the cobalt(III) diamine six-membered rings found in the Cambridge Structural Database into chair, boat, unsymmetric twist-boat, and delta and lambda twist-boat conformations. Of all of the six-membered rings analyzed, 80% adopt the energetically favored chair conformation. Twist boats are favored for steric reasons, while the high-energy boats are only found when the six-membered ring is structurally prevented from adopting a chair or twist-boat conformation. This is the first inorganic cluster analysis to published. The conformations of all of the nonchairs, except one, could be found by generating all of the possible combinations of the different idealized conformations of five- and six-membered rings and minimizing them.