Structure and bonding in face- 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 levels in edge- and face-bridged octahedral clusters. Based on these molecular orbital spectra, the closed-shell electronic structures are discussed. For face-bridged clusters, electron counts of 20 and 24 are derived for those clusters without an interstitial atom or with an interstitial main group. Eighteen or 24 electrons are required to satisfy closed-shell electronic structures for clusters with an interstitial transition-metal atom. For edge-bridged clusters, 14 or 16 electrons meet the closed-shell electronic requirements for those clusters without an interstitial main group atom. For clusters with an interstitial transition-metal atom, 14, 18 and 20 electron counts are possible. Based on the electron counts derived, several possible new clusters are predicted. Copyright (C) 1996 Elsevier Science Lt