Synthesis and Structures of Zirconium−Pyrrolyl Complexes: Computational Analysis of the Factors That Influence the Coordination Modes of Pyrrolyl Ligands

The first series of structurally characterized zirconium complexes that feature both η 1 - and η 5 -pyrrolyl coordination modes is reported. Specifically, 2,5-diarylpyrrolyl [pyr Ar 2 ] ligands (Ar = Ph, 2,4-Xyl) have been used to prepare [pyr Ar 2 ]Zr(NMe 2 ) 3 (NMe 2 H), [pyr Ar 2 ]Zr(NMe 2 ) 3, [pyr Ar 2 ]Zr(NMe 2 )I 2, and [η 5 -pyr Ar 2 ] 2 ZrCl 2 . DFT calculations indicate that the relative stabilities of the various coordination modes are influenced by both steric factors and the Lewis acidity of the metal center.