TY - JOUR
T1 - Re(I) complexes of substituted dppz
T2 - A computational and spectroscopic study
AU - Van Der Salm, Holly
AU - Fraser, Michael G.
AU - Horvath, Raphael
AU - Cameron, Scott A.
AU - Barnsley, Jonathan E.
AU - Sun, Xue Zhong
AU - George, Michael W.
AU - Gordon, Keith C.
N1 - Copyright:
Copyright 2014 Elsevier B.V., All rights reserved.
PY - 2014/3/17
Y1 - 2014/3/17
N2 - A series of dipyrido[3,2-a:2′,3′-c]phenazine (dppz)-based ligands with electron-withdrawing substituents and their [Re(CO) 3(L)Cl] and [Re(CO)3(L)(py)]PF6 complexes have been studied using Raman, resonance Raman, and transient resonance Raman (TR2) and time-resolved infrared (TRIR) spectroscopic techinques in conjunction with computational chemistry as well as electrochemical studies, emission, and absorption of ground and excited states. DFT (B3LYP) frequency calculations show good agreement with nonresonant Raman spectra, which allowed these to be used to identify phenanthroline, phenazine, and delocalized modes. These band assignments were used to establish the nature of chromophores active in resonance Raman spectra, probed with wavelengths between 350.7 and 457.9 nm. X-ray crystallography of [Re(CO)3(dppzBr2)Cl] and [Re(CO)3(dppzBr)(py)]PF6 showed these crystallize in space groups triclinic P1 and monoclinic P21/n, respectively. Electrochemical studies showed that substituents have a strong effect on the phenazine MO, changing the reduction potential by 200 mV. Transient absorption studies showed that generally the [Re(CO)3(L)(py)]PF6 complexes had longer lifetimes than the corresponding [Re(CO)3(L)Cl] complexes; the probed state is likely to be 3π → π* (phz) in nature. TR2 spectra of the ligands provided a marker for the triplet π → π* state, and the TR2 spectra of the complexes suggest an intraligand (IL) π,π* state for [Re(CO) 3(L)(py)]+ complexes, and a potentially mixed IL/MLCT state for [Re(CO)3(L)Cl] complexes. TRIR spectroscopy is more definitive with THEXI state assignments, and analysis of the metal-carbonyl region (1800-2100 cm-1) on the picosecond and nanosecond time scales indicates the formation of MLCT(phen/phz) states for all [Re(CO) 3(L)Cl] complexes, and IL π → π* (phen) states for all [Re(CO)3(L)(py)]+ complexes, with all but [Re(CO) 3(dppzBr(CF3))(py)]+ showing some contribution from an MLCT(phen) state also.
AB - A series of dipyrido[3,2-a:2′,3′-c]phenazine (dppz)-based ligands with electron-withdrawing substituents and their [Re(CO) 3(L)Cl] and [Re(CO)3(L)(py)]PF6 complexes have been studied using Raman, resonance Raman, and transient resonance Raman (TR2) and time-resolved infrared (TRIR) spectroscopic techinques in conjunction with computational chemistry as well as electrochemical studies, emission, and absorption of ground and excited states. DFT (B3LYP) frequency calculations show good agreement with nonresonant Raman spectra, which allowed these to be used to identify phenanthroline, phenazine, and delocalized modes. These band assignments were used to establish the nature of chromophores active in resonance Raman spectra, probed with wavelengths between 350.7 and 457.9 nm. X-ray crystallography of [Re(CO)3(dppzBr2)Cl] and [Re(CO)3(dppzBr)(py)]PF6 showed these crystallize in space groups triclinic P1 and monoclinic P21/n, respectively. Electrochemical studies showed that substituents have a strong effect on the phenazine MO, changing the reduction potential by 200 mV. Transient absorption studies showed that generally the [Re(CO)3(L)(py)]PF6 complexes had longer lifetimes than the corresponding [Re(CO)3(L)Cl] complexes; the probed state is likely to be 3π → π* (phz) in nature. TR2 spectra of the ligands provided a marker for the triplet π → π* state, and the TR2 spectra of the complexes suggest an intraligand (IL) π,π* state for [Re(CO) 3(L)(py)]+ complexes, and a potentially mixed IL/MLCT state for [Re(CO)3(L)Cl] complexes. TRIR spectroscopy is more definitive with THEXI state assignments, and analysis of the metal-carbonyl region (1800-2100 cm-1) on the picosecond and nanosecond time scales indicates the formation of MLCT(phen/phz) states for all [Re(CO) 3(L)Cl] complexes, and IL π → π* (phen) states for all [Re(CO)3(L)(py)]+ complexes, with all but [Re(CO) 3(dppzBr(CF3))(py)]+ showing some contribution from an MLCT(phen) state also.
UR - http://www.scopus.com/inward/record.url?scp=84896358032&partnerID=8YFLogxK
U2 - 10.1021/ic403056g
DO - 10.1021/ic403056g
M3 - Article
AN - SCOPUS:84896358032
SN - 0020-1669
VL - 53
SP - 3126
EP - 3140
JO - Inorganic Chemistry
JF - Inorganic Chemistry
IS - 6
ER -