Interconnection of the indenyl ligands of bis(indenyl)zirconium dichloride complexes by a1,1'-positioned Me
2Si or (CH
2)
2 bridge causes pronounced bathochromic shifts of the longestwavelength UV/vis absorption bands by ca. 50 nm, while much smaller shifts are caused bya Me
2Si bridge in otherwise analogous bis(cyclopentadienyl) complexes. Extended HückelMO calculations show that overlap between the empty 4d orbitals of the ZrCl
22+ fragmentand the highest filled
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orbitals of the indenyl anions is decreased when a Me
2Si bridgeforces the indenyl ligands into a lateral orientation. Consequences of this orbital mismatch,e.g. on electron densities at the Zr center, are discussed.