title: Effect of sulfur-based substituents on the electronic properties of Re(I) dppz complexes.
abstract: A series of sulfur-substituted dppz-based ligands and their Re(I)(CO)(3)Cl complexes are reported. The sulfur-substituted ligands and complexes show interesting electronic properties atypical of dppz-type systems. Substitution of dppz with thiocyanate (SCN) groups results in behavior typical of an electron withdrawing group. However, substitution of dppz with the electron donating trithiocarbonate (S(2)CS) or deca-alkylthioether (Sdec) groups confer intraligand charge-transfer (ICT) from the S adduct to the phenazine lowest unoccupied molecular orbital (LUMO). Upon complexation of the substituted dppz ligand to Re(CO)(3)Cl this ICT red-shifts and increases in intensity. Analysis of these observations using density functional theory (DFT) calculations and resonance Raman spectroscopy reveals that these transitions are a mixture of metal-to-ligand charge-transfer (MLCT) and S --> phenazine ICT in nature. The synthesized compounds are also characterized using (1)H NMR spectroscopy, IR spectroscopy, and electrochemistry. Single-crystal X-ray analysis was performed on dppz(SCN)(2) (C(20)H(18)N(6)S(2) a = 8.780 A, b = 9.792 A, c = 10.400 A, alpha = 95.95 degrees , beta = 112.13 degrees , gamma = 95.38 degrees , triclinic, P1, Z = 2, R1 = 0.0306, wR2 = 0.0829.
authors.affiliation: MacDiarmid Institute for Advanced Materials and Nanotechnology, Department of Chemistry, University of Otago, Dunedin 9001, New Zealand.
authors.forename: Michael G
authors.initials: MG
authors.lastname: Fraser
authors.forename: Allan G
authors.initials: AG
authors.lastname: Blackman
authors.forename: Garth I S
authors.initials: GI
authors.lastname: Irwin
authors.forename: Campbell P
authors.initials: CP
authors.lastname: Easton
authors.forename: Keith C
authors.initials: KC
authors.lastname: Gordon
mesh_terms: D018360:Crystallography, X-Ray; D004583:Electrons; D008958:Models, Molecular; D015394:Molecular Structure; D009942:Organometallic Compounds / Q000737:chemistry*; D010619:Phenazines / Q000737:chemistry*; D012211:Rhenium / Q000737:chemistry*; D013457:Sulfur Compounds / Q000737:chemistry*
chemical_list: D009942:Organometallic Compounds; D010619:Phenazines; D013457:Sulfur Compounds; C443808:dipyrido(3,2-a-2',3'-c)phenazine; D012211:Rhenium