10.1021/om0302490.s002 Anand Sundararaman Anand Sundararaman Roger A. Lalancette Roger A. Lalancette Lev N. Zakharov Lev N. Zakharov Arnold L. Rheingold Arnold L. Rheingold Frieder Jäkle Frieder Jäkle Structural Diversity of Pentafluorophenylcopper Complexes. First Evidence of π-Coordination of Unsupported Arenes to Organocopper Aggregates American Chemical Society 2003 unsymmetrical η 2 NMR toluene molecules meta carbon atoms tetrameric cluster species Cu DMSO 2003-08-18 00:00:00 Journal contribution https://acs.figshare.com/articles/journal_contribution/Structural_Diversity_of_Pentafluorophenylcopper_Complexes_First_Evidence_of_Coordination_of_Unsupported_Arenes_to_Organocopper_Aggregates/3362062 The binding behavior of arenes toward pentafluorophenylcopper was investigated. Crystallization of pentafluorophenylcopper from a mixture of 1,2-dichloroethane and cyclohexane affords the homoleptic tetrameric complex [Cu(C<sub>6</sub>F<sub>5</sub>)]<sub>4</sub>, whereas a π-complex, [Cu(C<sub>6</sub>F<sub>5</sub>)]<sub>4</sub>(η<sup>2</sup>-toluene)<sub>2</sub>, is obtained from toluene solution. The unique coordination of two toluene molecules in [Cu(C<sub>6</sub>F<sub>5</sub>)]<sub>4</sub>(η<sup>2</sup>-toluene)<sub>2</sub> leads to major structural changes as the regular square planar tetramer is distorted toward a butterfly structure with one short and one long diagonal Cu···Cu distance of 2.5935(3) and 3.955(1) Å, respectively. The toluene molecules are bound in an unsymmetrical η<sup>2</sup>-coordination mode with the shortest contacts observed between copper and the <i>meta</i> carbon atoms (<i>d</i>(Cu−C) = 2.271(2), 2.298(2) Å) and slightly longer distances to the <i>para</i> positions (<i>d</i>(Cu−C) = 2.339(2), 2.455(4) Å). Multinuclear NMR studies show that complexation to the intact tetrameric cluster species also occurs in neat solution of the aromatic species. Strongly coordinating solvents such as acetonitrile or DMSO, however, lead to aggregate breakdown.