Trigonal Prismatic Hexakis(Arylthiolato)Zirconate Complexes: Experimental Complement To Theory Kristin Kirschbaum, Jan Friese, Arndt Krol, Carsten Puke, and Dean M. Giolando*, Department of Chemistry, University of Toledo, Toledo, OH 43606

A classic question of transition metal coordination chemistry deals with the anomalous trigonal prismatic geometry of the [M(dithiolene)₃]- and [M(1,2-S₂C₆H₄)₃]-complexes. We have recently reported the existence of unexpected distortions from an octahedral geometry in several six coordinate thiolate complexes of titanium; [NMe₂H₂] ₂[Ti(1,2-S₂C₆H₄)₃], [NH₂Me₂][Ti₂(SMe)₉] and [Ti₃(SMe)₁₂]. Recently, [ZrMe₆]^2- was reported as the first example of a trigonal prismatic complex possessing only unidentate ligands. In our hands treating [ZrMe₆]^2- with aryl thiols provided a facile route to homoleptic thiolate complexes of zirconium having the formula [Zr(SR)₆]^2-, which possess coordination geometries near the trigonal prismatic limit. In this poster we present results on the synthesis and structural characterization of [Zr(S-C₆H₄-4-X)₆]^2- where X = H (1^2-) or OMe (2^2-). Complex 1^2- verifies the computational studies on d⁰ complexes that indicate the trigonal prismatic geometry is favored when the interaction between metal and ligand is primarily through [sigma]-bonds. Furthermore, in accordance with theoretical arguments, increasing the ligand [pi]-donor ability leads to complexes favoring the octahedral geometry. In complex 2^2- the para-OMe group is an electron donor by resonance effects, which promotes the pi-donor ability of the SC₆H₄-4-OMe ligand, thereby inducing the observed trigonal twist from the trigonal prism.