Inorganic Chemistry, Vol.47, No.2, 632-644, 2008
Coupling of CpCr(CO)(3) and heterocyclic dithiadiazolyl radicals. Synthetic, X-ray diffraction, dynamic NMR, EPR, CV, and DFT studies
The reaction of the 1,2,3,5-dithiadiazolyls (4-R-C6H4CN2S2)(2) (R = Me, 2a; Cl, 2b; OMe, 2c; and CF3, 2d) and (3-NC-5-(BU)-B-t-C6H3CN2S2)(2) (2e) with [CpCr(CO)(3)](2) (CP = eta(5)-C5H5) (1) at ambient temperature respectively yielded the complexes CpCr(CO)(2)(eta(2)-S2N2CC6H4R) (R = 4-Me, 3a; 4-Cl, 3b; 4-OMe, 3c; and 4-CF3, 3d) and CpCr(CO)(2)-(eta(2) -S2N2CC6H3-3-(CN)-5-(Bu-t)) (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-C6H4-CN2S2Cl (R = OMe, 8c; CF3, 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 H-1 NMR studies were carried out on complex 3d. Hybrid DFT calculations were performed on the model system [CpCr(CO)(2)S2N2CH] and comparisons are made with the reported CpCr(CO)(2)(pi-allyl) complexes.