WEAK HYDROGEN-BONDS FROM CP DONORS TO C-C ACCEPTORS

In the crystal structure of 1, pairs of molecules are connected by mut ual C(Cp)-H ... C=C interactions which have a geometry suggestive of w eak hydrogen bonding (1=[(eta(5)-C5H5)Fe(C=C - C7H7-2,4,6)(CO)(2)]). T he shorter of the H ... C distances is only 2.59 Angstrom, which is a distance that is typically observed for C-H ... C=C hydrogen bonds of stronger donors such as chloroform or alkyne groups. (C) 1998 Elsevier Science S.A. All rights reserved.