Procedures for the high-yield preparations of a range of copper(1) carboxylates, Cu0,CR (R = H, Me, CH2CI, CHCI,, CF,, CH,CN. CH,SH, Et, Pr9 Ph, o-N02*C6H,, CH=CHPh, and CH=CH-C02H) are reported. The i.r. spectra of these compounds are briefly discussed. The mass spectra of a selection of the copper( I) carboxylates show the presence of dimeric ions in high abundance in the vapour, together with very low abundances of trimeric and tetrameric ions. The alkanecarboxylates initially lose RCO,' from the radical ion Cu,(O,CR),+*, whereas the arenecarboxylates also easily lose C 0 2 from this radical ion leading to the formation of many ions containing Cu-C bonds. The monochloroacetate and o-nitrobenzoate also fragment to give ions possessing Cu-CI and CU-NO, bonds respectively.

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.

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Reactions of copper(\) acetate with various nitrogen-, phosphorus-, arsenic-, sulphur-, and selenium-donor ligands have been studied. With unidentate donors, either [Cu(O,CMe)L,] (L = thiourea or selenourea) or [Cu(O,CMe)L,] (L = Ph,P or imidazoline-2-thione) are formed. With the bidentate donors, 1 .

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