Ferrocene-Containing Tin(IV) Complexes Based on o-Benzoquinone and o-Iminobenzoquinone Ligands. Synthesis, Molecular Structure, and Electrochemical Properties

Svetlana V Baryshnikova; Andrey I Poddel'sky; Ekaterina V Bellan; Ivan V Smolyaninov; Anton V Cherkasov; Georgy K Fukin; Nadezhda T Berberova; Vladimir K Cherkasov; Gleb A Abakumov

doi:10.1021/acs.inorgchem.9b03757

Ferrocene-Containing Tin(IV) Complexes Based on o-Benzoquinone and o-Iminobenzoquinone Ligands. Synthesis, Molecular Structure, and Electrochemical Properties

Inorg Chem. 2020 May 18;59(10):6774-6784. doi: 10.1021/acs.inorgchem.9b03757. Epub 2020 Apr 27.

Authors

Svetlana V Baryshnikova¹, Andrey I Poddel'sky¹, Ekaterina V Bellan¹, Ivan V Smolyaninov^{2

3}, Anton V Cherkasov¹, Georgy K Fukin¹, Nadezhda T Berberova³, Vladimir K Cherkasov¹, Gleb A Abakumov¹

Affiliations

¹ G. A. Razuvaev Institute of Organometallic Chemistry, Russian Academy of Sciences, Tropinina strasse 49, Nizhny Novgorod 603137, Russia.
² Federal State Budgetary Institution of Science "Federal Research Centre the Southern Scientific Centre of the Russian Academy of Sciences", Chehova avenue 41, Rostov-on-Don 344006, Russia.
³ Astrakhan State Technical University, Tatisheva strasse 16, Astrakhan 414025, Russia.

PMID: 32338505
DOI: 10.1021/acs.inorgchem.9b03757

Abstract

The addition of different substituted o-benzoquinones and o-iminobenzoquinones to tin(II) bis(o-iminophenolates) of the types (Fc-IP)₂Sn^II and (Fc-4,6-IP)₂Sn^II (where Fc-IP is anion 2-(ferrocenylmethyleneamino)phenolate [Fc-C(H)═N(C₆H₄)O^-] and Fc-4,6-IP is anion 2-(ferrocenylmethyleneamino)-4,6-di-tert-butylphenolate [Fc-C(H)═N(4,6-tBu-C₆H₂)O^-]) in tetrahydrofuran leads to the oxidation of Sn(II) to Sn(IV) with formation of the corresponding tin(IV) catecholates (Fc-4,6-IP)₂Sn^IV(3,6-Cat) (1), (Fc-IP)₂Sn^IV(3,6-Cat) (2), (Fc-4,6-IP)₂Sn^IV(4-Cl-3,6-Cat) (3), (Fc-IP)₂Sn^IV(4-Cl-3,6-Cat) (4), (Fc-4,6-IP)₂Sn^IV(4,5-Cl₂-3,6-Cat) (5), and (Fc-IP)₂Sn^IV(4,5-Cl₂-3,6-Cat) (6) or the o-amidophenolates (Fc-4,6-IP)₂Sn^IV(AP-Me) (7), (Fc-IP)₂Sn^IV(AP-iPr) (8), and (Fc-4,6-IP)₂Sn^IV(AP-iPr) (9). Here ligands 3,6-Cat, 4-Cl-3,6-Cat, and 4,5-Cl₂-3,6-Cat are dianions 3,6-di-tert-butyl-, 4-chloro-3,6-di-tert-butyl-, and 4,5-dichloro-3,6-di-tert-butylcatecholates, respectively, and AP-Me and AP-iPr are dianions 4,6-di-tert-butyl-N-(2,6-dimethylphenyl)-o-amidophenolate and 4,6-di-tert-butyl-N-(2,6-diisopropylphenyl)-o-amidophenolate, respectively. Complexes 1-9 have been characterized in detail by IR spectroscopy, cyclic voltammetry, and ¹H, ¹³C, and ¹¹⁹Sn NMR spectroscopy. The molecular structures of tin(IV) complexes 5, 7, and 9 in the crystalline state were determined by single-crystal X-ray diffraction analysis. Complexes demonstrate a series of successive oxidations involving alternately catecholato/o-amidophenolato centers and ferrocenyl moieties. The relative oxidation potentials of these redox centers depend on the acceptor properties of the redox-active chelating O,O' or O,N ligand. An increase in the acceptor properties of redox-active o-quinonato-type ligands leads to an increase in the oxidation potentials of redox ligands as well as the following oxidation of ferrocenyl group(s). In two series of complexes, (Fc-4,6-L)₂SnL' and (Fc-L)₂SnL', where L' is AP-iPr, AP-Me, 3,6-Cat, 4-Cl-3,6-Cat, and 4,5-Cl₂-3,6-Cat, a more pronounced convergence of the oxidation potentials of the redox-active o-quinonato ligand and ferrocenyl group occurs in the series (Fc-L)₂SnL'.