STRUCTURE AND BONDING IN FACE-BRIDGED AND EDGE-BRIDGED OCTAHEDRAL TRANSITION-METAL CLUSTERS

A simple and unified picture based on the orbital interaction idea is developed to promote understanding of the complex molecular orbital le vels in edge- and face-bridged octahedral clusters. Based on these mol ecular orbital spectra, the closed-shell electronic structures are dis cussed. For face-bridged clusters, electron counts of 20 and 24 are de rived for those clusters without an interstitial atom or with an inter stitial main group. Eighteen or 24 electrons are required to satisfy c losed-shell electronic structures for clusters with an interstitial tr ansition-metal atom. For edge-bridged clusters, 14 or 16 electrons mee t the closed-shell electronic requirements for those clusters without an interstitial main group atom. For clusters with an interstitial tra nsition-metal atom, 14, 18 and 20 electron counts are possible. Based on the electron counts derived, several possible new clusters are pred icted. Copyright (C) 1996 Elsevier Science Ltd