Edge-Bridged Tetrahedral Geometry of Five-Coordinate d0 Complexes, Relatives of the Bent [MCp2L3] Family:  A Theoretical and Structure-Correlation Study

The edge-bridged tetrahedral geometry of five-coordinate d0 complexes [MD2L3] with strong π-donors D is analyzed with extended Hückel methodology as well as density functional theory. It is shown that this geometry, also encountered in bent metallocene systems [MCp2L3], can be considered as a distortion of a regular trigonal bipyramid arising from a second-order Jahn−Teller distortion of e‘ symmetry (in D3h) and corresponds to a deformation along a reversed-Berry pathway. This model was tested with a structure-correlation analysis of all experimentally determined [MD2L3] structures, thus allowing a mapping of the reversed-Berry pathway. The catalytic potential of these complexes and their isolobal relationship to [MCp2L3] are emphasized.