X-ray Structure and Variable Temperature NMR Spectra of [meso-Triarylcorrolato]copper(III)

Abstract

The diamagnetic square planar d(8) complexes [meso-arylcorrolato]copper(III) become paramagnetic upon warming, indicative of the equilibrium between the [corrolato]copper(III) and the [corrolato](+)* copper(II) forms of the complex. [meso-Triphenylcorrolato]copper(III) was structurally characterized and found to be saddled.

Experimental and Theoretical Investigations of the Existence of CuII, CuIII, and CuIV in Copper Corrolato Complexes

“…All of the bond distances and angles are comparable to those of previously reported Cu III corrolato molecules. [15] Thec entral copper atom fits well into the cavity of the corrolato ring in as lightly distorted square planar geometry with aminimal deviation of 0.0301 from the N 4 plane.T he distortion is due to slight deviations in the N-Cu-N bite angles in the range of 82.2-96.68 8 from the ideal ones.A saconsequence,the pyrrole-ring nitrogen atoms are tilted with respect to the mean corrolato plane (19 atom corrole ring) by distances alternately varying from À0.133 t o+ 0.252 . This saddled structure stabilizes the compound.…”

“…TheCu ÀNdistances in 3 lie between 1.873 a nd 1.907 a nd are at par with the earlier reported characteristic Cu III À Nb onds. [15] Thes ubstituted phenyl rings at the 5-and 15-meso-positions and the naphthyl group at the 10-position have been found to form dihedral angles of 42.58 8,5 8.58 8,a nd 62.58 8 with the mean corrolato plane.…”

“…Theresolution of the spectrum for 1C + is rather poor,and hence the data presented for that complex should be seen as approximate limits.However,for 2C + and 3C + ,the resolution of the spectra is good enough to allow the extraction of g and A tensors with reasonable accuracy.T he in situ generated one-electron-oxidized species 3C + in CH 2 Cl 2 /0.1m Bu 4 NPF 6 displays ap attern that also points to ap redominantly copper-centered spin. [15] Simulation of the spectrum of 3C + delivered an axial g tensor with values of g // = 2.089 and g ? = 2.035.…”

Ligand Noninnocence in Coinage Metal Corroles: A Silver Knife‐Edge

“…[1] In other words, copperc orroles have as ubstantial Cu II -corroleC 2À character.T he strength of the metal-corrole spin coupling varies from weak, as reflected in thermally accessible triplets tates for simple coppert riarylcorroles, to quite strong for the most strongly saddledc omplexes. [1,3,4,5,9,10] Gold(III) corroles by contrasta re innocent and relatively planar, regardless of the degree of peripheral steric hindrance. [11][12][13] The difference between copperand gold was strikingly illustrated in crystallographic studies of highly sterically hindered b-octakis(trifluoromethyl)-meso-triarylcorrole complexes, in which the copper complex was found to be extremely saddled, [4] with adjacent pyrrole rings essentially orthogonal to one another,w hile the gold complext urned out to be perfectly planar.…”

Electronic Structure of Copper Corroles

“…Themetal centre displays adistorted square planar geometry,with d(CuÀN) = 1.883-1.899 bond lengths,w hich is consistent with other Cu corrole structures. [15,16] Thec orrole adopts the typical nonplanar, saddled geometry, [6,9,10] where alternating pyrrole units point above and below the plane of the macrocycle.…”