title: Linear trichromium complexes with the anion of 2,6-di(phenylimino)piperidine.
abstract: The anion of 2,6-di(phenylimino)piperidine (DPhIP) has been found to support linear chains of three metal atoms. Three new compounds, [Cr3(DPhIP)4Cl]Cl.(1).5CH2Cl2.0.5H2O (1.1.5CH2Cl2.0.5H2O), [Cr3(DPhIP)4(CH3CN)]- (PF6)2.H2O.4CH3CN (2.H2O.4CH3CN), and [Cr3(DPhIP)4(F)(CH3CN)](BF4)2.5CH3CN (3.5CH3CN), have been synthesized and characterized by X-ray crystallography. Compound 1 has a linear chain of three chromium atoms arranged in an unsymmetrical fashion, with two of them forming a quadruply bonded unit (Cr-Cr distance 1.932(2) A) and the third being a non-metal-metal-bound 5-coordinate unit (Cr...Cr distance 2.659(2) A). The fifth coordination site is occupied by a chloride ion, and another chloride ion is located in the interstices of the crystal. The trimetal unit in compound 2 is structurally similar to that in compound 1 except that the axial ligand in 2 is a CH3CN molecule. Compound 3 is an oxidation product prepared by reaction of 1 with AgBF4. Here, a square pyramidal CrIII unit, FCrN4, and a Cr-Cr quadruply bonded (Cr-Cr distance 1.968(2) A) unit, with an axially coordinated acetonitrile molecule, form the trichromium chain. The CrIII...CrII separation of 2.594(2) A in 3 is too long to be considered a bonding interaction.
authors.affiliation: Laboratory for Molecular Structure and Bonding, Department of Chemistry, P.O. Box 30012, Texas A&M University, College Station, Texas 77842-3012, USA.
authors.forename: R
authors.initials: R
authors.lastname: Clérac
authors.forename: F A
authors.initials: FA
authors.lastname: Cotton
authors.forename: L M
authors.initials: LM
authors.lastname: Daniels
authors.forename: K R
authors.initials: KR
authors.lastname: Dunbar
authors.forename: C A
authors.initials: CA
authors.lastname: Murillo
authors.forename: H C
authors.initials: HC
authors.lastname: Zhou