Crystal and molecular structure of tetrakis[copper(I) benzoate]

Abstract

Crystals of the title compound are triclinic, space group P i , cell dimensions a = 15.408(7), b = 13.784(12), c = 15.034(9) 8, cc = 92.43(6), p = 62.34(5), y = 11 2.71 (6)". Z = 4. 2 262 Independent reflections above background were collected by counter methods; the structure was solved by direct methods and refined by fullmatrix least squares to R 0.064. There are two independent tetramers in the asymmetric unit which have similar but not identical geometries in which four copper atoms form a parallelogram (internal angles 114.5, 65.5 and 108.8,71.2" respectively in the two tetramers), with minimum Cu * . Cu distances of 2.71 A. The four benzoates bridge adjacent Cu --Cu atoms around the parallelogram and are alternately above and below the plane. The Cu-0 distances are ca. 1.84 A.ALTHOUGH copper(1) formate and acetate were first isolated over seventy years ago,l it is only in the past few years that the chemistry of copper(1) carboxylates has been studied in any depth. This revival of interest stems from the knowledge that these compounds are involved as intermediates in decarboxylation reactions of organic acids and in synthetic procedures such as the formation of esters from organic acids and alkyl halides in the presence of copper(1) oxide., There has recently been some attention paid to the structural aspects of these compounds. Copper(1) acetate has been shown to be a planar polymeric molecule in which chains of A.

Breaking Infinite CuI Carboxylate Helix Held by Cuprophilicity into Discrete Cun Fragments (n = 6, 4, 2)

“…The structure of the previously reported copper(I) pivalate (2) can also be regarded as a double helix. The Cu(n-2)-Cu(n)-Cu(n+2) angles in 2 of 143.66 (6)°imply that the helical twist in 2 is greater than that in 1. A projection array perpendicular to the a axis in 2 exhibits a perfect pentagon of copper atoms.…”

“…The longest intermetallic separation, Cu(5)··· Cu(6), of 3.143(2) Å is neighbored by the shorter Cu(4)··· Cu(5) and Cu(6)···Cu(7) contacts of 2.730(2) and 2.693(2) Å, respectively. This discrepancy in metal-metal distances is also reflected in the geometry of the carboxylate bridge between Cu(5) and Cu (6), which results in the Cu(5)-O(10)-C and Cu(6)-O(11)-C angles being 128.1(7) and 135.3(8)°, respectively. At the same time, the average value for the rest of the Cu-O-C angles is 124.8(7)°.…”

“…These (6), were isolated in the form of airstable but slightly moisture sensitive crystals of pale yellow color. Their IR spectra are very similar in the 2000-500 cm -1 range and indicate the presence of aromatic and carboxylate functions.…”

“…(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008) for crystal growth, we have recently accomplished the preparation and structural characterization of [Cu 2 (O 2 C(2,6-CF 3 ) 2 C 6 H 3 ) 2 ] ϱ [9] (Scheme 1, a), [Cu 4 (O 2 C(3-F)C 6 H 4 ) 4 ] and [Cu 4 (O 2 C(2,3,4-F) 3 (c), and [Cu 6 (O 2 C(3,5-F) 2 C 6 H 3 ) 6 ] [11] (d). Thus, the known structural types of copper(I) carboxylates range from discrete [6,10,11] to infinite motifs, [5,[7][8][9] based on mono-, [8] di-, [5,9] tetra-, [6,7,10] or hexanuclear [11] copper(I) units.…”

“…Thus, the known structural types of copper(I) carboxylates range from discrete [6,10,11] to infinite motifs, [5,[7][8][9] based on mono-, [8] di-, [5,9] tetra-, [6,7,10] or hexanuclear [11] copper(I) units. Such structural diversity is fascinating but not well rationalized so far.…”