Metal–carbonyl and metal–nitrosyl complexes. Part II. Crystal and molecular structure of the tricarbonylchromiumanisole–1,3,5-trinitrobenzene complex

Abstract

Crystals of the 1 : 1 electron donor–acceptor complex formed from tricarbonylchromiumanisole and 1,3,5-trinitrobenzene are monoclinic, space group P2₁/c, with a= 10·10, b= 13·42, c= 13·87 Å, β= 101° 45′, Z= 4. A three-dimensional single-crystal X-ray analysis has shown that the benzene rings of the two components are inclined at 3°, that is, they are very nearly parallel, with perpendicular distances from the aromatic carbon atoms of the anisole molecule to the plane of the trinitrobenzene molecule ranging from 3·34 to 3·50 Å(average 3·41 Å). The benzene rings of the anisole and trinitrobenzene molecules are tilted by 24 and 27°, respectively, out of the orientation perpendicular to the line joining the centres of the rings. In the trinitrobenzene component the ring valency angles at the carbon atoms carrying nitro-groups (123°) are significantly greater than the valency angles at the other carbon atoms (117°); an explanation based on σ-bond hybridisation is suggested.