title: Crystal structures of two cross-bridged chromium(III) tetra-aza-macrocycles.
abstract: The crystal structure of di-chlorido-(4,10-dimethyl-1,4,7,10-tetra-aza-bicyclo-[5.5.2]tetra-deca-ne)chromium(III) hexa-fluorido-phosphate, [CrCl2(C12H26N4)]PF6, (I), has monoclinic symmetry (space group P21/n) at 150 K. The structure of the related di-chlorido-(4,11-dimethyl-1,4,8,11-tetra-aza-bicyclo-[6.6.2]hexa-deca-ne)chromium(III) hexa-fluorido-phosphate, [CrCl2(C14H30N4)]PF6, (II), also displays monoclinic symmetry (space group P21/c) at 150 K. In each case, the Cr(III) ion is hexa-coordinate with two cis chloride ions and two non-adjacent N atoms bound cis equatorially and the other two non-adjacent N atoms bound trans axially in a cis-V conformation of the macrocycle. The extent of the distortion from the preferred octa-hedral coordination geometry of the Cr(III) ion is determined by the parent macrocycle ring size, with the larger cross-bridged cyclam ring in (II) better able to accommodate this preference and the smaller cross-bridged cyclen ring in (I) requiring more distortion away from octa-hedral geometry.
authors.affiliation: Department of Chemistry, University of Hull, Cottingham Road, Hull HU6 7RX, England.
authors.forename: Timothy J
authors.initials: TJ
authors.lastname: Prior
authors.affiliation: Department of Chemistry and Physics, Southwestern Oklahoma State University, Weatherford, OK 73096, USA.
authors.forename: Danny L
authors.initials: DL
authors.lastname: Maples
authors.affiliation: Department of Chemistry and Physics, Southwestern Oklahoma State University, Weatherford, OK 73096, USA.
authors.forename: Randall D
authors.initials: RD
authors.lastname: Maples
authors.affiliation: Department of Natural Science, McPherson College, McPherson, KS 67460, USA.
authors.forename: Wesley A
authors.initials: WA
authors.lastname: Hoffert
authors.affiliation: Department of Natural Science, McPherson College, McPherson, KS 67460, USA.
authors.forename: Trenton H
authors.initials: TH
authors.lastname: Parsell
authors.affiliation: Department of Chemistry, University of Hull, Cottingham Road, Hull HU6 7RX, England.
authors.forename: Jon D
authors.initials: JD
authors.lastname: Silversides
authors.affiliation: Department of Chemistry, University of Hull, Cottingham Road, Hull HU6 7RX, England.
authors.forename: Stephen J
authors.initials: SJ
authors.lastname: Archibald
authors.affiliation: Department of Chemistry and Physics, Southwestern Oklahoma State University, Weatherford, OK 73096, USA.
authors.forename: Timothy J
authors.initials: TJ
authors.lastname: Hubin
keywords: chromium complexes; cross-bridged macrocycle; crystal structure