The stereochemistry of (5exo-acylcyclohexa-1,3-diene)tricarbonyliron derivatives and the crystal structure of (5-exo-cyanocyclohexa-1,3-diene)tricarbonyliron

(5-Cyanocyclohexa-1,3-diene)tricarbonyliron reacts with Grignard reagents to yield a series of (5-acylcyclohexa-1,3-diene)tricarbonyliron complexes. The cyano derivative crystallises in space group Pna21, with Z = 3, and cell dimensions of a 28.235(19), b 6.498(7), c 11.114(10) Å. The structure was solved by Patterson and Fourier methods, and final residuals were R = 0.070 and R w = 0.057 on 803 observed intensity data. The molecules are monomeric and the cyano ligand adopts the exo stereochemistry.