1
|
Nazarov DI, Andronov MG, Kuzmin AV, Khasanov SS, Yudanova EI, Shestakov AF, Otsuka A, Yamochi H, Kitagawa H, Konarev DV. Macrocycle- and metal-centered reduction of metal tetraphenylporphyrins where the metal is copper(II), nickel(II) and iron(II). Dalton Trans 2021; 50:15620-15632. [PMID: 34668904 DOI: 10.1039/d1dt02573b] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
The reduction of metal(II) tetraphenylporphyrins, where metal(II) is copper, nickel or iron, has been performed in toluene solution in the presence of a cryptand. Cesium anthracenide was used as a reductant. Crystalline salts {cryptand(Cs+)}2{CuII(TPP4-)}2- (1) and {cryptand(Cs+)}{NiI(TPP2-)}-·C6H5CH3 (2) have been obtained. The two-electron reduction of {CuII(TPP2-)}0 is centered on the macrocycle allowing one to study for the first time the structure and properties of the TPP4- tetraanions in the solid state. Tetraanions have a diamagnetic state and show essential C-Cmeso bond alternation. New bands attributed to TPP4- appear at 670, 770 and 870 nm. Unpaired S = 1/2 spin is localized on CuII. The one-electron reduction of {NiII(TPP2-)}0 centered on nickel provides the formation of {NiI(TPP2-)}- with unpaired S = 1/2 spin localized on NiI at 100(2) K. The effective magnetic moment of 2 is 1.68μB at 120 K and a broad asymmetric EPR signal characteristic of NiI is observed for 2 and also for (Bu3MeP+){NiI(TPP2-)}-·C6H5CH3 (3) in the 4.2-120 K range. Since dianionic TPP2- macrocycles are present at 100(2) K, no alternation of C-Cmeso bonds is observed in 2. The excited quartet S = 3/2 state according to the calculations is positioned close to the ground S = 1/2 state. In the excited state, charge transfer from NiI to the macrocycle takes place resulting in the formation of NiII with S = 1 and TPP˙3- with S = 1/2 in the {NiII(TPP˙3-)}- anions. Therefore, the increase in the magnetic moment of 2 above 150 K is attributed to the population of the excited quartet state with a gap of 750 K. Salt 2 is EPR silent above 150 K and manifests absorption bands characteristic of TPP˙3- at RT. The reduction of NiII(TPP2-) and FeII(TPP2-) by cesium anthracenide in the presence of Bu3MeP+ yields crystals of 3 and (Bu3MeP+){FeI(TPP2-)}-·C6H5CH3 (4) whose crystal structures and optical properties are also presented. DFT calculations have been carried out for {MII(TPP2-)} (M = Cu, Ni and Fe) and their anions to interpret the experimental results obtained for 1-4.
Collapse
Affiliation(s)
- Dmitry I Nazarov
- Institute of Problems of Chemical Physics RAS, Chernogolovka, Moscow region, 142432 Russia.
| | - Mikhail G Andronov
- Institute of Problems of Chemical Physics RAS, Chernogolovka, Moscow region, 142432 Russia. .,Moscow State University, Leninskie Gory, 119991 Moscow, Russia
| | - Aleksey V Kuzmin
- Institute of Solid State Physics RAS, Chernogolovka, Moscow region, 142432 Russia
| | - Salavat S Khasanov
- Institute of Solid State Physics RAS, Chernogolovka, Moscow region, 142432 Russia
| | - Evgeniya I Yudanova
- Institute of Problems of Chemical Physics RAS, Chernogolovka, Moscow region, 142432 Russia.
| | - Alexander F Shestakov
- Institute of Problems of Chemical Physics RAS, Chernogolovka, Moscow region, 142432 Russia. .,Moscow State University, Leninskie Gory, 119991 Moscow, Russia
| | - Akihiro Otsuka
- Division of Chemistry, Graduate School of Science, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan.,Research Center for Low Temperature and Materials Sciences, Kyoto University, Sakyo-ku, Kyoto 606-8501, Japan
| | - Hideki Yamochi
- Division of Chemistry, Graduate School of Science, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan.,Research Center for Low Temperature and Materials Sciences, Kyoto University, Sakyo-ku, Kyoto 606-8501, Japan
| | - Hiroshi Kitagawa
- Division of Chemistry, Graduate School of Science, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan
| | - Dmitri V Konarev
- Institute of Problems of Chemical Physics RAS, Chernogolovka, Moscow region, 142432 Russia.
| |
Collapse
|