CRYSTAL STRUCTURE OF COPPER SOAPS

Abstract

Attached

The crystal and rno l ecu.la r structures of the rn eta IIi c anhydrous soaps, copper caprate and copper caprylate, have been determined using the standard techniques of X-ray crystallography. A dim e riz ed structure with two copper atorn s at the centres of two opposite faces 'of a cube rn a de by eight oxygen atorn s at its co rners was found in both structures and so is confirm cd as cornrrio n to rna ny m em be r s of this series of soaps. Both these cornpounds have space group PI and they both have two hydrocarbon chains per rn ol ecul e , The two hydrocarbon chains pack nearly parallel to each other over a part of their lengths. The int cr= atorn ic distance of rn eta Ilic copper is only a little shorter than the separation . of copper atorn s in these two corn pou nd s. Another fo r m of copper caprate, with a rnorio c.Linic ('lIe. unit cell and space group &e:f was identified. This form. of -e copper caprate, however, was a unit cell app r oxim at el.y eight tirn e s bigger in voIurn e than the tr icIini c fo rrn , Although the basic features of the tricIini c fo rrn s of copper caprate and copper caprylate are sirn iIa r , the orientat ions of the hydrocarbon chains with res pect to their cell edges are different. The three corn.pounds copper butyrate, 4" copper valerate and copper caprylate can be groupecitogether in every aspect of the crystallography of these three soaps. Crystallographically copper cap r at e , however, falls into the same category as other higher members of the series. Some preliminary investigations into the pos sibilit y of obtaining single crystals of manganous caprate are also explained. Three different forms of this compound were identified using X-ray diffraction powder methods.