Grzegorz Rusek

Copper(II), nickel(II) and zinc(II) coordination by dihydroxamic acids

Abstract Potentiometric titrations, absorption and e.p.r. spectra were used to establish coordination equilibria in Cu(II), Ni(II) and Zn(II) solutions with tetramethylenodihydroxamic acid and hexamethyleno-N,N′-diethylodihydroxamic acid. Results have shown that in all systems the major complexes formed at basic pH are dinuclear species. The complexes formed by dihydroxamic acids were found to be distinctly more stable than those of monohydroxamic acids.

Synthesis, reactivity and structure of [Ir4(μ-CO)3(CO)5(μ-PPh2pyl)(PPh2pyl)2]

Abstract Ir( 4 (CO) 12 reacts with P(Ph 2 pyl) 3 giving [Ir 4 (μ-CO) 3 (CO) 5 (μ-PPh 2 pyl)(PPh 2 pyl) 2 ] containing one phosphine bridging ligand coordinating via P and N atoms and [Ir 4 (μ-CO) 3 (CO) 6 (PPh 2 pyl) 3 ] which in solution is at equilibrium with the former cluster.

Structural investigations of 3-acetamido-4-nitrobenzal derivatives

Abstract N-(p-dimethylaminophenyl)-α-(3acetamido-4-nitrophenyl)nitrone (I) and 3-acetamido-4-nitrobenzylpyridinium bromide (II) were synthesized and their crystal structures were determined by X-ray diffraction methods. The geometry of carbon–nitrogen bond in nitrone is trans. In I the acetamido moiety slightly deviates from plane to the rest of molecule. The intramolecular N–H⋯O and C–H⋯O as well as intermolecular C–H⋯O hydrogen bonds stabilize the crystal structures of both the compounds. NMR investigations of II have given spectra with extra signals in comparison to the number of expected that suggests that dominating structure of this compound observed in crystal state coexists in solution with comparable amount of the additional form due to an interaction with solvent and increasing conformational freedom. For II duplication of signal number is observed for the 3-acetamido-4-nitrobenzyl substituent due to formation only of two different edge to face structures of this compound in DMSO and D2O solution. For I in DMSO solution the major form has perpendicular orientation of N,N-dimethylaniline substituent on nitrone bond against the plane containing the rest of the molecule.

Nitro derivatives of 3-acetamidobenzyl acetate

The structures of 3-acetamido-2-nitrobenzyl acetate, C 11 H 12 N 2 O 5 , (I), 3-acetamido-6-nitrobenzy acetate, C 11 H 12 N 2 O 5 , (II) and 3-acetamido-6-nitrobenzyl acetate monohydrate, C 11 H 12 N 2 O 5 .H 2 O, (III), have been determined at low temperature; 150K for (I) and (III), and 100 K for (II). The molecules differ mainly in the conformation of the acetamide and acetate groups with respect to the aromatic ring plane: in (II) they are almost coplanar, in (I) they are markedly distorted from planarity, while in (III) they are intermediate. The nitro group is twisted with respect to the aromatic ring in (I), but is almost coplanar with it in (II) and (III). In all three structures, one of the nitro O atoms is directed towards a methylene C atom, approximately bisecting the H-C-H angles, and intramolecular C-H...O hydrogen bonds involving the aromatic H and carboxyl O atoms are observed. In all three cases, the crystal structures are stabilized by intermolecular N-H...O [and O-H...O in (III)], as well as weak C-H...O. hydrogen bonds.

The crystal and molecular structure of (dibenzo-18-crown-6) oxonium tetrachloroferrate(III)

Abstract The crystal structure of [(dibenzo-18-crown-6)H 3 O + ](FeCl − 4 ) has been determined by X-ray diffraction and refined to R = 0.06 for 1811 non-zero independent reflections. The oxonium cation is located in the center of the ether cavity. The O(oxonium)⋯O(crown) distances vary from 2.63(1) to 2.73(1) A. Hydrogen bonding interations of the oxonium ion with two O atoms of the crown and with one Cl atom from FeCl − 4 anion are observed.