Keto-acid chloride and diketone intermediates in the acylation of ferrocene by arylene bis-acid chlorides. Crystal and molecular structure of 4-ferrocenylcarbonyl-4 '-chlorocarbonylbiphenyl: intermolecular association by means of strong C-H center dot center dot center dot O hydrogen bonds and pi center dot center dot center dot pi stacking interactions

Acylation of ferrocene with arylene bis-acid chlorides yields deep-red poly meric products. However, under controlled conditions two types of intermedi ate can be isolated and characterised: the keto-acid chlorides FcCO(arylene )COCl 1 [Fc = (C5H5)Fe(C5H4); a arylene = 4,4'-C6H4C6H4, b arylene = 1,3-C6 H4, c arylene = 1,4-C6H4], followed in the case of 1a and 1b by the diketon es FcCO(arylene)COFc 2a and 2b, although no conversion of 1c to 2c occurs. Similarly, use of 1,3,5-benzenetricarbonyl trichloride yielded 1,3,5-C6H3(C OFc)(3). In the crystal structure of 1a, there are four independent molecul es: pairs of molecules are linked into dimers by strong C-H ... O hydrogen bonds, and these dimers are linked into chains by pi...pi stacking interact ions. (C) 1999 Elsevier Science S.A. All rights reserved.