B. K. Shcherbakov

NewN-substituted 1-hydroxy-3-aminopropylidenediphosphonic acids

N-Substituted 1-hydroxy-3-aminopropylidenediphosphonic acids were synthesized. Their acid-base and complexation properties toward a wide series of metal cations in water were investigated.

Spectroscopic study of copper(II) complexes with 1,4,7-tris(dihydroxyphosphorylmethyl)-1,4,7-triazacyclononane and 1,4,7-tris(β-dihydroxyphosphorylethyl)-1,4,7-triazacyclononane

The reaction of 1,4,7-tris(dihydroxyphosphorylmethyl)-1,4,7-triazacyclononane and 1,4,7-tris(β-dihydroxyphosphorylethyl)-1,4,7-triazacyclononane with divalent copper over a wide pH range in aqueous solution has been studied using electronic, vibrational, and ESR spectroscopy. Normal and protonated complexes of both compounds have a pentacoordinate structure of the tetragonal type with coordination of three nitrogen atoms and two phosphonic groups. The difference lies in the different degree of distortion and flexibility of the square-pyramidal polyhedron.

Synthesis and acid-base and complexing properties of amino-substituted?-hydroxyalkylidenediphosphonic acids

1. We have synthesized new amino-substitutedα-hydroxyalkylidenediphosphonic acids. 2. We have measured the acid dissociation constants of these compounds and the stability constants of their complexes with Ca2+, Co2+, and Cu2+ ions.

?-Hydroxy-?-[N,N-bis(dihydroxyphosphorylmethyl)-amino]propylidenediphosphonic acid as a complexone

Conclusions1.α-Hydroxy-γ-[N,N-bis(dihydroxyphosphorylmethyl)amino]propylidenediphosphonic acid was synthesized, and its pKa values for dissociation and the stability constants of complexes with a number of alkaline earth and transition metals were determined. The presence of both hydroxyalkylidenediphosphonic and iminobis(methylphosphonic) acid fragments in the molecule of the investigated complexone increases the stabilities of the complexes.2.The synthesized acid has a zwitter-ion structure, and the betaine proton dissociates last.

Ionic dissociation and complex formation in α-hydroxy-γdimethylaminopropylidenediphosphonic acid

Conclusions1.The order of dissociation of α-hydroxy-γ-dimethylaminopropylidenediphosphonic acid has been determined from the study of IR spectra of the acid in H2O and D2O solutions, and from the complexing of the acid with certain alkali, alkaline-earth, rare-earth, and transition-metal ions.2.The introduction of an amino group into the molecule of a hydroxyalkylidenediphosphonic acid has no effect on the stability of the normal complexes of the metals covered by this work, but increase the stability of the protonated complexes by a factor of approximately 2. The complexes in question here are highly soluble.

Synthesis and acid-base properties of phosphorylated diazacycloalkanes and their cyclic analogs

Novel cyclopendant organophosphorus complexing agents,viz. 1,5-bis(2-diphenylphosphorylmethyl (or ethyl))-1,5-diazacyclooctane (1, 2) and l-methyl-4-(2-diphenylphosphorylethyl) piperazine (3), were synthesized on the basis of 1,5-diazacyclooctane and piperazine. The protonation constants of the compounds synthesized and some of their analogs were determined by potentiometric titration in 70 % aqueous ethanol and in nitromethane. The nitrogen atoms of the ring are the protonation sites in all of the systems studied. The regularities of the variation of protonation constants have been explained by the formation of intramolecular hydrogen bonds. The conformational possibilities of the formation of H-bonds in the cations of the ligands have been examined by molecular mechanics.

Hydrogen bonds and the structure of perchlorates of phosphorylated diazacycloalkanes

Mono- and diperchlorates of phosphorylated diazacycloalkanes (PDAC),viz. 1,5-bis(2-diphenylphosphorylethyl) -1,5-diazacyclooctanes (1a, 1b), 1,4-bis(2-diphenylphosphorylethyl)- 1,4-piperazine (2a), and 1-methyl-4-(2-diphenylphosphorylethyl)-1,4-piperazines (3a, 3b), were prepared. The formation of inter- and intramolecular hydrogen bonds in PDAC perchlorates and some model compounds in the solid state and in solution was investigated by IR spectroscopy. The dependence between the effect of the hydrogen bond formation and association of the ions in solution was analyzed. Conformational analysis of the cations of PDAC was carried out.

Complex formation of 1,4,7-tris(β-diphenylphosphinylethyl)-1,4,7-triazacyclononane with divalent copper salts

An investigation of the monoligand complex of 1,4,7-tris(β-diphenylphosphinylethyl)-1,4,7-triazacyclononane with divalent copper has been carried out in various solvents using electronic, IR, and ESR spectroscopy. It was found that the five-coordination polyhedron formed in the complex involves only donor atoms of the ligand and has the structure of a tetragonally elongated square pyramid with two nitrogen atoms and two oxygen atoms at the base and a nitrogen atom at the apex. Compared with the copper(II) complex with the corresponding acid, 1,4,7-tris(β-dihydroxyphosphinylethyl)-1,4,7-triazacyclononane, the coordination compound studied has a higher order of symmetry. The absence of observable distortions in the case of the acid is probably connected with steric interaction of the bulky phenyl substituents in the test ligand.

PROTONATION OF PHOSPHINYLMETHYLPYRIDINES AND THEIR N-OXIDES IN NITROMETHANE

The protonation of phosphinylmethylpyridines with different structures and their N-oxides differing both in the nature and the number of functional groups (pyridine nitrogen, N → O, and P=O) was studied by potentiometric titration in nitromethane and IR spectroscopy. Regardless of the number of P=O groups, all the investigated phosphinylmethylpyridines were N bases, and their pK values changed in the range 10.4-4.7. In the case of N-oxides of phosphinylmethylpyridines, the oxygen atoms of N → O and P=O groups participated simultaneously in protonation, and the pK values were 6.7-5.0. The structure of the protonation products is discussed.

The complexing properties of 1,4,7-tris(dihydroxyphosphorylmethyl)-1,4,7-triazacyclononane

The complexation of 1,4,7-tris(dihydroxyphosphorylmethyl)-1,4,7-triazacyclononane with metal ions, differing in both charge and ionic radius, was studied. This complexing agent is selective relative to cations of a given ionic radius. The stability of the complex increases with increasing charge and polarizability of the cation.