title: Coupling of CpCr(CO)3 and heterocyclic dithiadiazolyl radicals. synthetic, x-ray diffraction, dynamic NMR, EPR, CV, and DFT studies.
abstract: The reaction of the 1,2,3,5-dithiadiazolyls (4-R-C(6)H(4)CN(2)S(2))(2) (R = Me, 2a; Cl, 2b; OMe, 2c; and CF3, 2d) and (3-NC-5-tBu-C(6)H(3)CN(2)S(2))(2) (2e) with [CpCr(CO)(3)](2) (Cp = eta(5)-C(5)H(5)) (1) at ambient temperature respectively yielded the complexes CpCr(CO)(2)(eta(2)-S(2)N(2)CC(6)H(4)R) (R = 4-Me, 3a; 4-Cl, 3b; 4-OMe, 3c; and 4-CF(3), 3d) and CpCr(CO)(2)(eta(2)-S(2)N(2)CC(6)H(3)-3-(CN)-5-(tBu)) (3e) in 35-72% yields. The complexes 3c and 3d were also synthesized via a salt metathesis method from the reaction of NaCpCr(CO)(3) (1B) and the 1,2,3,5-dithiadiazolium chlorides 4-R-C(60H(4)CN(2)S(2)Cl (R = OMe, 8c; CF(3), 8d) with much lower yields of 6 and 20%, respectively. The complexes were characterized spectroscopically and also by single-crystal X-ray diffraction analysis. Cyclic voltammetry experiments were conducted on 3a-e, EPR spectra were obtained of one-electron-reduced forms of 3a-e, and variable temperature 1H NMR studies were carried out on complex 3d. Hybrid DFT calculations were performed on the model system [CpCr(CO)(2)S(2)N(2)CH] and comparisons are made with the reported CpCr(CO)(2)(pi-allyl) complexes.
authors.affiliation: Department of Chemistry, National University of Singapore, Kent Ridge, Singapore 119260.
authors.forename: Hiu Fung
authors.initials: HF
authors.lastname: Lau
authors.forename: Pearly Chwee Ying
authors.initials: PC
authors.lastname: Ang
authors.forename: Victor Wee Lin
authors.initials: VW
authors.lastname: Ng
authors.forename: Seah Ling
authors.initials: SL
authors.lastname: Kuan
authors.forename: Lai Yoong
authors.initials: LY
authors.lastname: Goh
authors.forename: Alexey S
authors.initials: AS
authors.lastname: Borisov
authors.forename: Paul
authors.initials: P
authors.lastname: Hazendonk
authors.forename: Tracey L
authors.initials: TL
authors.lastname: Roemmele
authors.forename: René T
authors.initials: RT
authors.lastname: Boeré
authors.forename: Richard D
authors.initials: RD
authors.lastname: Webster