N-(aminoethyl)cyclam: a tetraaza macrocycle with a coordinating tail (scorpiand). Acidity controlled coordination of the side chain to nickel(II) and nickel(III) cations

Abstract

298ChemInform Abstract The novel functionalized macrocycle (III) is prepared from (I) and (II). A pH-dependent equilibrium is observed between the blue high-spin nickel(II) complex (IV) and the yellow low-spin complex (V). The nickel(II) complexes undergo a reversible one-electron process to give an authentic nickel(III) species in which the axial binding of the side arm is again controlled by the acidity.

Isolation and characterization of polydentate ligands derived from the reaction of pentaerythrityltetrabromide and ethylenediamine

“…This cationic moiety acts as an anion binding site close to the metal centre. Redox reactions involving perchlorate anion and divalent nickel complexes have been reported recently by Fabbrizzi and co-workers (20) in the case of N-aminoethylcyclam. ~i~+ complexes of amines L , and L2 have been found to exhibit such redox activity, and the trivalent nickel complex has been isolated in the case of ligand L6 and characterized crystallographically5.…”

Synthesis and Properties of Copper(II) Phthalocyanines with Monoazacrown and Crown Ethers as Peripheral Substituents

“…Except for -CON vibration, the remaining parts of the spectra of 3a and 3b are very similar to those of 4a and 4b respectively Detosylation of tetratosylated scorpiand 3b is verified by the changes in -SO 2 stretching around 1150-1330 cm À1 for the tosylated compounds; in addition, the characteristic absorption of the sulfonate can be differentiated between 4b and 4c (1100, 1220 cm À1 ). The difference between the spectra of tosylated amino and free amino groups (4b and 4c) is clear from the presence of SO 2 vibration in 4b at 1340-1150 cm À1 and free -NH 2 vibration in 4c at 3420-3340 cm 3.14 ppm, have been assigned on the basis of the results of previous work on crown ligands [6,17]. The aromatic protons of the azabenzo-15-crown-5 moiety appear as a singlet at 7.35 ppm in both 3a and 3b while those of benzo-15-crown-5 appear at higher field as a multiplet (double doublet and singlet) (7.01-6.89).…”

“…Among these we may cite N-, O-and S-containing functionalities such as crown ethers [6][7][8][9], monoazacrown ethers [10], tetraaza crown ethers [11,12], diaza and triaza crown ethers [13], tetrathia crown ethers [14], tetraazacrown ether double layers [12] and some homo-and heteropentanuclear complexes [11,12,15]. This paper describes for the first time the preparation and characterization of tetracrown ether-substituted copper phthalocyanine derived from N-[(4'-benzo-15-crown-5)oyl]-substituted monoazacrown ether (3a), as well as a novel functionalized macrocycle (3b) in which an NH 2 CH 2 CH 2 -chain is appended to a dibromomonoazacrown ether ring [16,17], and copper(II) phthalocyanine derived from this macrocycle. Furthermore, a less soluble phthalocyanine (4c) with multifunctional substituents attached to the aza position of the crown ether, obtained by detosylation is described.…”

Chemical and photochemical properties of a ruthenium nitrosyl complex with the N-monosubstituted cyclam 1-(3-Propylammonium)-1,4,8,11-tetraazacyclotetradecane

“…Evaluation of f NO at R = 0 % eliminates possible complications resulting from secondary photolysis of primary reaction products and inner filter effects. 9, 8.0, and 7.8, respectively, 48,54 and free propylammonium has a pK a of 9.8, 55,56 it is difficult to undoubtedly assign the pK a values. However, it is more likely that the pK a of 7.0 refers to the cyclam nitrogen and that of 8.2 to propylammonium, value that is lower than 9.8 due to the charge effect of the Ru metal center, as expected.…”