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Molecular Structures and Redox Properties of Homoleptic Aluminum(III) Complexes with Azobisphenolate (azp) Ligands
| Content Provider | MDPI |
|---|---|
| Author | Takahashi, Kazuyuki Noguchi, Takumi Ueda, Keiji Miyawaki, Atsuhiro Murata, Suguru |
| Copyright Year | 2022 |
| Description | To elucidate the oxidation behavior of the 2,2′-azobisphenolate (azp) ligand, a series of homoleptic 1:2 $Al^{III}$ complexes of four azp derivatives (L1) with 5,5′-dichloro-, 5,5′-dimethyl-, 5,5′-di-t-butyl-, 3,3′,5,5′-tetramethyl-substituents and of one imino derivative (L2) were synthesized and obtained as $TPP[Al(L)_{2}$]·solvent (TPP = tetraphenylphosphonium ion). The X-ray crystal structure analyses showed that the two ONO-tridentate ligands were meridionally coordinated to a central $Al^{III}$ ion in an almost perpendicular manner to give a homoleptic octahedral coordination structure in all the $Al^{III}$ complexes. The proton nuclear magnetic resonance spectra suggested that all the $Al^{III}$ complexes retained the homoleptic coordination structure in solution. From the cyclic voltammetry measurements in dichloromethane solutions, all the $Al^{III}$ complexes with the azp ligands showed two partially reversible oxidation waves, and an additional reversible or partially reversible reduction wave. The substitution effects on the first oxidation and reduction peak potentials were revealed in the $Al^{III}$ complexes with the azp ligands. On the other hand, the imino complex showed a partially reversible oxidation wave accompanying a film deposition. The density functional theory (DFT) calculations indicated that the molecular orbital (MO) coefficients of the frontier MOs in the $Al^{III}$ complexes were present on the ligands and were absent on the $Al^{III}$ ion. These results confirmed that the azp ligands are susceptible to oxidation and can give a relatively stable oxidation species depending upon substituent effects. |
| Starting Page | 84 |
| e-ISSN | 23046740 |
| DOI | 10.3390/inorganics10060084 |
| Journal | Inorganics |
| Issue Number | 6 |
| Volume Number | 10 |
| Language | English |
| Publisher | MDPI |
| Publisher Date | 2022-06-16 |
| Access Restriction | Open |
| Subject Keyword | Inorganics Inorganic Chemistry Azobisphenolate Ligand Aluminum Complex Redox-active Ligand Crystal Structure Redox Property Dft Calculation |
| Content Type | Text |
| Resource Type | Article |
