title: Electronic structures of bis- and monothiophene complexes with Fe, Co, Ni: a density functional theory study.
abstract: A density functional theory study for the bis- and monothiophene complexes of Fe, Co, and Ni (MT2 and MT, T = thiophene, M = Fe, Co, Ni) was performed to understand their coordination geometries, bonding properties, vibration spectra and singlet excited state spectra. The typical metal coordination exists in the complexes. The Fe-thiophene coordination has the highest stability, with Ni-thiophene being the second highest, and Co-thiophene the lowest. Bisthiophene complexes of Co and Ni prefer to homolytically dissociate to their monothiophene ones and free thiophene. Frequency calculation shows that the ligand-M-ligand asymmetric stretching vibration in bisthiophene complexes shows a strong absorption, at 435.2, 495.7, and 383 cm(-1) for Fe(eta4-T)2, Co(eta2-T)2 and Ni(eta2-T)2, respectively. The M-S stretching vibration in monothiophene complexes shows a strong absorption in the far-infrared region, at 209, 156, and 150 cm(-1) for Fe(eta4-T), Co(eta4-T) and Ni(eta5-T), respectively. The excited state spectra indicate that the characteristic absorption wavelengths of the complexes have a red shift of more than 12.40 eV compared to free thiophene, at 3.54, 1.64, 3.83, 2.75, 1.43, and 2.58 eV for Fe(eta4-T)2, Co(eta2-T)2, Ni(eta2-T)2, Fe(eta4-T), Co(eta4-T), and Ni(eta5-T), respectively.
authors.affiliation: School of Chemistry and Chemical Engineering, Shandong University, Jinan 250100, P. R. China.
authors.forename: Yunqiao
authors.initials: Y
authors.lastname: Ding
authors.forename: Maoxia
authors.initials: M
authors.lastname: He
authors.forename: Yuzhong
authors.initials: Y
authors.lastname: Niu
authors.forename: Dengxu
authors.initials: D
authors.lastname: Wang
authors.forename: Yan
authors.initials: Y
authors.lastname: Cui
authors.forename: Shengyu
authors.initials: S
authors.lastname: Feng