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Mechanistic Insight into the NN Bond‐Cleavage of Azo‐Compounds that was Induced by an AlAl‐bonded Compound [L 2− Al II Al II L 2− ]
Author(s) -
Zhao Yanxia,
Liu Yanyan,
Yang Ling,
Yu JianGuo,
Li Shaoguang,
Wu Biao,
Yang XiaoJuan
Publication year - 2012
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201103607
Subject(s) - diimine , chemistry , singlet state , medicinal chemistry , adduct , bond cleavage , ion , reductive elimination , stereochemistry , photochemistry , crystallography , catalysis , organic chemistry , excited state , physics , nuclear physics
An α‐diimine‐stabilized AlAl‐bonded compound [L 2− Al II Al II L 2− ] (L=[{(2,6‐ i Pr 2 C 6 H 3 )NC(Me)} 2 ]; 1 ) consists of dianionic α‐diimine ligands and sub‐valent Al 2+ ions and thus could potentially behave as a multielectron reductant. The reactions of compound 1 with azo‐compounds afforded phenylimido‐bridged products [L − Al III ( μ 2 ‐NPh)( μ 2 ‐NAr)Al III L − ] ( 2 – 4 ). During the reaction, the dianionic ligands and Al 2+ ions were oxidized into monoanions and Al 3+ , respectively, whilst the [NAr] 2− imides were produced by the four‐electron reductive cleavage of the NN double bond. Upon further reduction by Na, the monoanionic ligands in compound 2 were reduced to the dianion to give [(L 2− ) 2 Al III 2 (μ 2 ‐ NPh) 2 Na 2 (thf) 4 ] ( 5 ). Interestingly, when asymmetric azo‐compounds were used, the asymmetric adducts were isolated as the only products (compounds 3 and 4 ). DFT calculations indicated that the reaction was quite feasible in the singlet electronic state, but the final product with the triplet‐state monoanionic ligands could result from an exothermic singlet‐to‐triplet conversion during the reaction process.