Article

Thiocyanate linkage isomerism in a ruthenium polypyridyl complex.

Department of Chemistry, Yale University, P.O. Box 208107, New Haven, Connecticut 06520-8107, USA.
Inorganic Chemistry (Impact Factor: 4.79). 11/2011; 50(23):11938-46. DOI: 10.1021/ic200950e
Source: PubMed

ABSTRACT Ruthenium polypyridyl complexes have seen extensive use in solar energy applications. One of the most efficient dye-sensitized solar cells produced to date employs the dye-sensitizer N719, a ruthenium polypyridyl thiocyanate complex. Thiocyanate complexes are typically present as an inseparable mixture of N-bound and S-bound linkage isomers. Here we report the synthesis of a new complex, [Ru(terpy)(tbbpy)SCN][SbF(6)] (terpy = 2,2';6',2''-terpyridine, tbbpy = 4,4'-di-tert-butyl-2,2'-bipyridine), as a mixture of N-bound and S-bound thiocyanate linkage isomers that can be separated based on their relative solubility in ethanol. Both isomers have been characterized spectroscopically and by X-ray crystallography. At elevated temperatures the isomers equilibrate, the product being significantly enriched in the more thermodynamically stable N-bound form. Density functional theory analysis supports our experimental observation that the N-bound isomer is thermodynamically preferred, and provides insight into the isomerization mechanism.

0 Bookmarks
 · 
190 Views
  • [Show abstract] [Hide abstract]
    ABSTRACT: A combined experimental and computational study of three thiocyanate-Cu(II) complexes with general formula [Cu(Ln )2(NCS)]ClO4, (L1 = N,N-dimethyl,N′-benzyl-ethylenediamine, L2 = N,N-diethylyl,N′-benzyl-ethylenediamine, L3 = N,N-diisopropylyl,N′-benzyl-ethylenediamine) was carried out. The compounds were synthesized and structurally characterized by physico-chemical and spectroscopic methods. X-ray crystallography of [Cu(L1)2(NCS)]ClO4 showed that the copper atom achieves a distorted square pyramidal environment through coordination of four amine N atoms and a N atom of the terminal SCN− ion. To investigate the effect of steric crowding on the coordination mode of thiocyanate at the copper(II) center, DFT calculations are carried out on the complexes. Two different cases were considered, namely when nitrogen is the donor atom and when sulfur is the donor atom. In all cases, the N-coordinated isomers were always more stable than the S-coordinated ones. The electronic spectra of the complexes were analyzed and assigned by means of DFT/TD-DFT, together with molecular orbital analysis.
    Transition Metal Chemistry 04/2014; 39(3). · 1.40 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Three copper (II) complexes of type [Cu(L)2(NCX)]ClO4, 1–3, (L = N,N-dimethyl,N′-benzyl-1,2-diaminoethane and X = O, S and Se) were synthesized and characterized on the basis of microanalytical, spectroscopic and molar conductance. An X-ray diffraction study of [Cu(L)2(NCO)]ClO4 (1) reveals that the copper (II) center located in a distorted square pyramidal environment through coordination of four amine N atoms and a N atom of the terminal NCO−. Density functional theory (DFT) calculations were performed to understand the linkage isomerism of NCX− ligand from a theoretical point of view, to study the electronic structure of the complexes and the relative stabilities of the Cu–NCX/Cu–XCN isomers. DFT computational results buttressed the experimental observations indicating that the Cu–NCX isomer is more stable than Cu–XCN linkage isomer. Complexes 1 and 2 exhibit solvatochromism as evidenced from visible study in different solvents.
    Polyhedron 03/2013; 51:1-9. · 2.05 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Synthesis and X-ray structural characterization of three complexes of type cis-[M(dafone)2(NCS)2] (M = Co(II), 1; Ni(II), 2; Zn(II), 3; dafone = 4,5-diazafluoren-9-one) and a polymer cis-[Cd(dafone)(NCS)2]n (4) have been reported. Each of the four complexes is crystallized in orthorhombic crystal system. Structural study reveals that each metal(II) centre in the four complexes adopts distorted octahedral geometry with MN6 chromophore in 1-3 and MN4S2 chromophore in 4. The room temperature steady-state fluorescent intensity of dafone in dimethyl formamide at 402 nm is found to be quenched in these reported dafone complexes (1-4). Graphical Abstract Synthesis and X-ray structural characterization of three complexes of type cis-[M(dafone)2(NCS)2] (M = Co(II), 1; Ni(II), 2; Zn(II), 3; dafone = 4,5-diazafluoren-9-one) and a polymer cis-[Cd(dafone)(NCS)2]n (4) have been reported. The fluorescent intensity of dafone in DMF is found to be quenched in these reported dafone complexes (1-4).
    Journal of Chemical Sciences 05/2014; 126(3):717-725. · 1.22 Impact Factor

Full-text (2 Sources)

Download
65 Downloads
Available from
May 27, 2014