azole (3′-PyaiH) or its 1-alkyl derivative, 3′-PyaiR, with Ru(CO)3(PPh3)2 has synthesized air stable, moisture insensitive, diamagnetic Ru(0) complexes, [Ru(CO)(3′-PyaiR)(PPh3)2]. The ligands serve as an unsymmetric N,N′-chelating agent (N(imidazole) and N(azo) are abbreviated as N and N′, respectively). The X-raystructure determination of [Ru(CO)(3′-PyaiH)(PPh3)2] shows a square pyramidal geometry
Manganese(II) complexes of pyridyl-azo-imidazoles. Single crystal X-ray structures of 3′-PyaiH and [Mn(3′- PyaiEt)4](ClO4)2 (3′-PyaiH=2-(3′-pyridylazo)imidazole; 3′-PyaiEt=1-ethyl-2-(3′-pyridylazo)imidazole)
Pyridine and imidazole are connected by an azo group (-N=N-) to synthesize 2-[(3'-pyridyl)azo]imidazole (3'-PyaiH) and this has been confirmed by X-ray structure determination. The N(1)-alkylation gives 1-alkyl-2-[(3'-pyridyl)azo]imidazole (3'-PyaiR') (R' = Me (2a), Et (2b), Bz (2c)). The reaction between Mn(ClO4)(2) (.) 6H(2)O and 3'-PyaiR' in methanol has synthesized [Mn(3'-PyaiR')(4)](ClO4)(2) (3). The structure has been confirmed by single crystal X-ray diffraction study in one case, in addition to other spectral characterization. The structure reveals a tetrahedral orientation of four ligands coordinating through imidazole-N only. Cyclic voltammetry exhibits a Mn(III)/Mn(II) couple at > 1.1 V along with azo reductions. However, the reaction of MnCl2 (.) 4H(2)O + 3'-PyaiR' in the presence of NaN3 or NH4CNS (1:2:2 mole proportion) has synthesized Mn(3'-PyaiR')(2)(X)(2) (X = N-3 (4), NCS (5)). (c) 2005 Elsevier Ltd. All rights reserved.
First example of mixed azoheterocycles: structural studies of metallo-macrocycle Ag(I) versus tetrahedral Cd(II) complexes of pyridyl-azo-imidazole
Imidazolyl and 3'-pyridyl are linked by azo bond (-N=N-) to synthesize hitherto unknown mixed heterocyclic azo molecules, 2-[(3'-pyridyl)azo]imidazole (3'-PyaiH). Alkylation in presence of NaH has synthesized 1-alkyl-2-[(3-pyridyl)azo]imidazole (3'-PyaiR'). 3'-PyaiR' include three types of N-donor centers: N(imidazole), N(azo) and a peripheral N(pyridine). They bind to Ag+ to form 2:2 metallo-macrocycle, [Ag(3'-PyaiR')](2)(2+), while the reaction with Cd2+ forms Cd(3'-PyaiR')(4)(2+). The complexes are structurally characterized by X-ray diffraction studies. (C) 2004 Elsevier B.V. All rights reserved.
Imidazole→imidazolidine. Preparation by reduction of with NaBH4 and characterisation of the products (PyaiR=1-alkyl-2-{3′-(pyridylazo)}imidazole)
reaction of 2-(3′-pyridylazo)imidazole (PyaiH) or 1-alkyl-2-(3′-pyridylazo)imidazole (PyaiR) with [Os(H)(Cl)(CO)(PPh3)3][Os(H)(Cl)(CO)(PPh3)3] in THF or MeCN has synthesized stable red coloured [Os(H)(CO)(PPh3)2(Pyai)][Os(H)(CO)(PPh3)2(Pyai)] (2a) or [Os(H)(CO)(PPh3)2(PyaiR)](PF6)[Os(H)(CO)(PPh3)2(PyaiR)](PF6) (2b–2d). While the reaction of PyaiR and [Os(H)(Cl)(CO)(PPh3)3][Os(H)(Cl)(CO)(PPh3)3] in dry n-heptane