title: Nonlinear optical and related properties of iron(II) pentacyanide complexes with quaternary nitrogen electron acceptor units.
abstract: Three new complex salts Na(2)[Fe(II)(CN)(5)(L)] [L = N-methyl-4-{E,E-4-(4-pyridyl)buta-1,3-dienyl}pyridinium, N-methyl-4-{E,E,E-6-(4-pyridyl)hexa-1,3,5-trienyl}pyridinium, or N-methyl-1,4-bis-{E-2-(4-pyridyl)ethenyl}] benzene have been prepared. These compounds have been characterized by using various techniques including electronic absorption spectroscopy and cyclic voltammetry, allowing their properties to be compared with those of the known complexes where L = N-methylpyrazinium (Mepyz(+)), N-methyl-4,4'-bipyridinium, or N-methyl-4-[E-2-(4-pyridyl)ethenyl]pyridinium. Molecular quadratic nonlinear optical (NLO) responses have been determined by using hyper-Rayleigh scattering (HRS) at 1064 nm, and also via Stark (electroabsorption) spectroscopic studies on the intense, visible d --> pi* metal-to-ligand charge-transfer (MLCT) bands. The MLCT transitions show large red-shifts on moving from aqueous to methanol solutions, and these excitations are associated with relatively large static first hyperpolarizabilities beta(0). Single crystal X-ray structures of two hydrated materials containing the complex anion [Fe(II)(CN)(5)(Mepyz(+))](2-) have been determined, and both of these show some degree of alignment of the constituent complex dipoles.
authors.affiliation: School of Chemistry, University of Manchester, Oxford Road, Manchester M13 9PL, UK. b.coe@manchester.ac.uk
authors.forename: Benjamin J
authors.initials: BJ
authors.lastname: Coe
authors.forename: Simon P
authors.initials: SP
authors.lastname: Foxon
authors.forename: Elizabeth C
authors.initials: EC
authors.lastname: Harper
authors.forename: James
authors.initials: J
authors.lastname: Raftery
authors.forename: Rachel
authors.initials: R
authors.lastname: Shaw
authors.forename: Catherine A
authors.initials: CA
authors.lastname: Swanson
authors.forename: Inge
authors.initials: I
authors.lastname: Asselberghs
authors.forename: Koen
authors.initials: K
authors.lastname: Clays
authors.forename: Bruce S
authors.initials: BS
authors.lastname: Brunschwig
authors.forename: Anthony G
authors.initials: AG
authors.lastname: Fitch
mesh_terms: D018360:Crystallography, X-Ray; D055664:Electrochemical Techniques; D004579:Electron Transport; D005296:Ferrous Compounds / Q000737:chemistry*; D009584:Nitrogen / Q000737:chemistry*; D010084:Oxidation-Reduction; D012492:Salts / Q000737:chemistry; D013057:Spectrum Analysis
chemical_list: D005296:Ferrous Compounds; D012492:Salts; C058614:pentacyanoferrate (II); D009584:Nitrogen