2633-03-6Relevant articles and documents
2,2′-Azobispyridine in Phosphorus Coordination Chemistry: A New Approach to 1,2,4,3-Triazaphosphole Derivatives
Panova, Yulia S.,Sheyanova, Alexandra V.,Zolotareva, Nataliya V.,Sushev, Vyacheslav V.,Arapova, Alla V.,Novikov, Alexander S.,Baranov, Evgenii V.,Fukin, Georgy K.,Kornev, Alexander N.
, p. 4245 - 4254 (2018)
Oxidative addition of 2,2′-azobispyridine (abpy) to PCl3 in CH2Cl2 or THF gave the 1:1 addition product, containing phosphorus in high oxidation state (+5) and a reduced form of the ligand. 2,2′-Hydrazobispyridine (hbpy) was prepared by reduction of abpy with hydrazine-hydrate in 63 % yield. Interaction of hbpy with PCl3 in the presence of triethylamine gave (abpy)2–PCl (2) in 25 % preparative yield. A similar reaction of hbby with (Et2N)2PCl afforded (abpy)2–PNEt2 (4) in 89 % yield. Compound 4 after work-up with PCl3 or PBr3 gave 2 and (abpy)2–PBr (6) respectively in high yields. Diethylamino-derivative 4 formed (κ2-N,N) adduct with SiCl4 7 (coordination by Py and azo-functions), while the chloro-derivative 2 did not. Reaction of 2 with PCl5 is accompanied with liberation of PCl3 and formation of spirocyclic ate complex [(abpy)2–2P]+PCl6–. All structurally characterized compounds demonstrated short distances between pyridyl nitrogen and the phosphorus atom. However, the QTAIM analysis did not reveal the presence of appropriate bond critical points (3, –1) for the intramolecular noncovalent interactions N···P in 2, 4, and 6. We theoretically estimated values of the rotation barriers for the pyridyl and Et2N moieties in 4 using the relaxed potential energy surface scan at the B3LYP/6-31G(d) level of theory. The values of rotation barriers are very close to each other, viz. 13.2 (pyridyl) and 13.0 (Et2N) kcal/mol.
Red-light activated photoCORMs of Mn(i) species bearing electron deficient 2,2′-azopyridines
Kottelat,Ruggi,Zobi
, p. 6920 - 6927 (2016/05/19)
The realization of CO releasing molecules triggered by light (photoCORMs) within the phototherapeutic window (λ > 600 nm) constitutes an important goal for potential therapeutic applications of the molecules. The activation of photoCORMs with red/NIR light would enable exploiting the higher depth of penetration of this radiation with respect to higher energy photons. In this article we report a family of carbonyl Mn(i) complexes capable of releasing CO when triggered with red light (≥625 nm). Such complexes are based on 2,2′-azopyridine ligands modified by the introduction of electron-donating or electron-withdrawing substituents. Our results indicate that electron deficient ligands induce a gradual decrease of the HOMO-1/LUMO gap of the species (i.e. of the orbitals involved in the lowest energy transition), thus enabling a fine tuning of their visible absorption maxima between 630 and 693 nm. The synthesis of the complexes and their photodecomposition behaviour towards CO release are described. We suggest that this approach could be generalized for further development of low-energy activated photoCORMs.
New heteroaromatic azo compounds based on pyridine, isoxazole, and benzothiazole for efficient and highly selective amidation and mono-N-benzylation of amines under Mitsunobu conditions
Iranpoor, Nasser,Firouzabadi, Habib,Khalili, Dariush
experimental part, p. 923 - 934 (2010/10/01)
4,4′-Azopyridine (2c) is used in conjunction with triphenylphosphine for the efficient conversion of carboxylic acids into amides via Mitsunobu reaction with primary and secondary aliphatic and aromatic amines. The highly selective amidation of only primary aromatic amines with new heterogeneous azo compounds based on benzothiazole 2d and isoxazole 2e is also described. These azo compounds 2c-2e can also be applied for selective mono-N-benzylation of primary aromatic amines. The solid side product heteroaromatic hydrazines obtained under the developed Mitsunobu conditions are easily separated by simple filtration and can be reoxidized to azo compounds for further use.
