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 d 0 complexes [MD 2 L 3 ] 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 [MCp 2 L 3 ], can be considered as a distortion of a regular trigonal bipyramid arising from a second-order Jahn−Teller distortion of e‘ symmetry (in D 3 h ) and corresponds to a deformation along a reversed-Berry pathway. This model was tested with a structure-correlation analysis of all experimentally determined [MD 2 L 3 ] structures, thus allowing a mapping of the reversed-Berry pathway. The catalytic potential of these complexes and their isolobal relationship to [MCp 2 L 3 ] are emphasized.