title: Proper and improper hydrogen bonds in metalloorganic crystal architecture: experimental evidence in [CoCp(2)](+) and [FeCp(2)](+) salts.
abstract: The [FeCp2]+ and [CoCp2]+ salts are the first examples of metalloorganic complexes where the proton donor eta5-Cp shows both "proper" and "improper" hydrogen bonds when it is involved in intermolecular bonding with different anionic proton acceptors. Blue or red shift of the C-H stretching frequency is the clear experimental evidence.
authors.affiliation: Dipartimento di Chimica IFM, Università di Torino, Via P Giuria 7, 10125 Torino, Italy.
authors.forename: Eliano
authors.initials: E
authors.lastname: Diana
authors.forename: Pier Luigi
authors.initials: PL
authors.lastname: Stanghellini