Zbigniew Ciunik

Palladium Vacataporphyrin Reveals Conformational Rearrangements Involving Hückel and Möbius Macrocyclic Topologies

5,10,15,20-Tetraaryl-21-vacataporphyrin (butadieneporphyrin, an annulene-porphyrin hybrid) which contains a vacant space instead of heteroatomic bridge acts as a ligand toward palladium(II). The metal ion of square-planar coordination geometry is firmly held via three pyrrolic nitrogen atoms where the fourth coordination place is occupied by a monodentate ligand or by an annulene part of vacataporphyrin. The macrocycle reveals the unique structural flexibility triggered by coordination of palladium. The structural rearrangements engage the C(20)C(1)C(2)C(3)C(4)C(5) annulene fragment which serves as a linker between two pyrrolic rings of vacataporphyrin albeit the significant ruffling of the tripyrrolic block is also of importance. Two fundamental modes of interactions between the palladium ion and annulene moiety have been recognized. The first one resembles an eta(2)-type interaction and involves the C(2)C(3) unit of the butadiene part. Alternatively the profound conformational adjustments allowed an in-plane coordination through the deprotonated trigonally hybridized C(2) center of butadiene. The coordinated vacataporphyrin acquires Hückel or extremely rare Möbius topologies readily reflected by spectroscopic properties. The palladium vacataporphyrin complexes reveal Hückel aromaticity or Möbius antiaromaticity of [18]annulene applying the butadiene fragment of vacataporphyrin as a topology selector. The properties of specific conformers were determined using (1)H NMR and density functional theory calculations.

A Direct Link between Annulene and Porphyrin Chemistry-21-Vacataporphyrin

A novel molecule, aza-deficient porphyrin 5,10,15,20-tetraaryl-21-vacataporphyrin has been synthesised by a substraction of a tellurium atom from 5,10,15,20-tetraaryl-21-telluraporphyrin under treatment of HCl. The new macrocycle is an annulene-porphyrin hybrid and at the same time is directly related to 21-heteroporphyrins but has a vacant space instead of heteroatomic bridge. The molecule preserves the fundamental structural and spectroscopic features of the parental 5,10,15,20-tetraarylporphyrin with three nitrogen atoms and two CH groups favorably prearranged for coordination.

Structure, properties and cytostatic activity of tributyltin aminoarylcarboxylates

Abstract Properties of butyltin complexes [Sn(C4H9-n)3{OOCC6H3(NH2)2-3,4}]n (1), [Sn(C4H9-n)3{OOCC6H3(NH2)2-3,5}] (2), [Sn(C4H9-n)3{OOCC6H4NNC6H4N(CH3)2-4}] (3) and [Sn(C6H5)3{OOCC6H3(NH2)2-3,5}]n (4) have been investigated. 1H, 13C and 119Sn NMR spectra indicate that the compounds in chloroform are distorted tetrahedral and in strongly coordinating solvents trigonal-bipyramidal complexes. Structure of complex 3 has been determined by X-ray crystallography. This compound adopts trigonal bipyramidal structure with bridging carboxylato ligand bound asymmetrically with tin atoms in axial positions. The complexes are effective cytostatic agents.

Rhodium(III) complexes with polypyridyls and pyrazole and their antitumor activity

Abstract Synthesis and properties of rhodium complexes with nitrogen ligands [RhCl 2 (Hpz) 4 ][RhCl 4 (Hpz) 2 ] ( 1 ), [RhCl 3 (tpy)] ( 2 ), [RhCl 3 (tpta)]·H 2 O ( 3 ) and [Rh(tpy) 2 (Him)]Cl 3 ·3H 2 O ( 4 ), have been described. X-ray structures of complexes 1 – 3 have been determined. IR, UV–Vis and 1 H NMR spectra of the complexes have been discussed. Cytostatic activity of the complexes against HCV29T tumor cells increases in the series: 1 3 2 4 . The cytostatic activity of complex 4 is greater than that of cisplatin. Interaction of the complexes with DNA has been investigated.

X-ray Crystal Structures, Electron Paramagnetic Resonance, and Magnetic Studies on Strongly Antiferromagnetically Coupled Mixed μ-Hydroxide-μ-N1,N2-Triazole-Bridged One Dimensional Linear Chain Copper(II) Complexes

Four new metal-organic polymeric complexes, {[Cu(mu-OH)(mu-ClPhtrz)][(H 2O)(BF 4)]} n ( 1), {[Cu(mu-OH)(mu-BrPhtrz)][(H 2O)(BF 4)]} n ( 2), {[Cu(mu-OH)(mu-ClPhtrz)(H 2O)](NO 3)} n ( 3), and {[Cu(mu-OH)(mu-BrPhtrz)(H 2O)](NO 3)} n ( 4) (ClPhtrz = N-[( E)-(4-chlorophenyl)methylidene]-4 H-1,2,4-triazol-4-amine; BrPhtrz = N-[( E)-(4-bromophenyl)methylidene]-4 H-1,2,4-triazol-4-amine), were synthesized in a reaction of substituted 1,2,4-triazole and various copper(II) salts in water/acetonitrile solutions. The structures of 1- 4 were characterized by single-crystal X-ray diffraction analysis. The Cu(II) ions are linked both by single N (1), N (2)-1,2,4-triazole and hydroxide bridges yielding one dimensional (1D) linear chain polymers. The tetragonally distorted octahedral geometry of copper atoms is completed alternately by two water and two BF 4 (-) anion molecules in 1 and 2 but solely by two water molecules in 3 and 4. Magnetic properties of all complexes were studied by variable temperature magnetic susceptibility measurements. The Cu(II) ions are strongly antiferromagnetically coupled with J = -419(1) cm (-1) ( 1), -412(2) cm (-1) ( 2), -391(3) cm (-1) ( 3), and -608(2) cm (-1) ( 4) (based on the Hamiltonian H = - J[ summation operator S i . S i+ 1]). The nature and the magnitude of the antiferromagnetic exchange were discussed on the basis of complementarity/countercomplementarity of the two competing bridges.

Rhodium wires based on binuclear acetate-bridged complexes

Abstract The synthesis, properties, structure and conductivity of a new class of one-dimensional, mixed valence Rh(I)–Rh(II) complexes { Rh 2 ( μ-O 2 CMe ) 2 ( N – N ) 2 ][ BX 4 ]} n ( N – N =bipyridine, phenanthroline; X=F, Ph) are described.

New aspects of weak CH⋯π bonds: intermolecular interactions between alicyclic and aromatic rings in crystals of small compounds, peptides and proteins

Abstract The geometry of intermolecular contacts between alicyclic and aromatic rings in a number of crystal structures suggests an attractive interaction between the rings. An analysis of molecular packing of 444 different crystal structures collected in the Cambridge Structural Database shows that phenyl…cyclohexanonyl, cyclohexyl, and/or cyclopentyl ring interactions occur in 59–82% of studied crystals. Similar interactions are observed between aromatic rings and heterocyclic pyrrolidine rings of proline in peptides and proteins. An analysis of data collected in the Brookhaven Protein Data Bank reveals that interactions between proline CH groups and aromatic rings of phenylalanine, tyrosine, and tryptophan as acceptors are frequently observed in proteins. Based on these results, several geometric models of these interactions are proposed. Two of these models are fully optimized using quantum chemical calculations at the density functional theory level. Calculated energies suggest that the most important interaction between the cyclohexanone and benzene rings is described by the face-to-face model, in which three axial hydrogen atoms are directed toward the aromatic partner.

Chemistry of palladium phosphinite (PPh2(OR)) and phosphonite (P(OPh)2(OH)) complexes: catalytic activity in methoxycarbonylation and Heck coupling reactions

The new phosphinite and phosphonite complexes (1-8) are very efficient catalysts for the methoxycarbonylation of iodobenzene and Heck cross-coupling of bromobenzene with butyl acrylate. High catalytic activity of these complexes can be explained by their in situ transformations during the reaction, stimulated by the presence of water, acid (HCl) or base (NEt(3)). Hydrolysis of phosphinite palladium complexes of the form trans-PdCl(2)[PPh(2)(OR)](2) (R = C(6)F(5), 2, (t)Bu 3, or O-menthyl 4) results in the formation of the dimeric complex [mu-ClPd(PPh(2)OH)(PPh(2)O)](2) 5, which is deprotonated by NEt(3), producing a polymeric complex of formula [Pd(P(O)PPh(2))(2)](n) 8. The reverse reaction, protonolysis of 8 with HCl, leads back to 5 and the monomeric complex 5a. The phosphinite complex PdCl(2)[PPh(2)(OBu)](2)1 with a more lipophilic ligand, PPh(2)(OBu), does not undergo hydrolysis under the same conditions. In the reaction of PdCl(2)(cod) with P(OPh)(2)(OH), the new dimer [mu-ClPd(P(OPh)(2)OH)(P(OPh)(2)O)](2) 6 was obtained, whereas reaction of Pd(OAc)(2) with P(OPh)(2)(OH) leads to the polymeric complex [Pd[P(O)(OPh)(2)](2)](n) 7. Protonolysis of 7 with HCl results in the formation of 6.

When in the presence of the strong hydrogen bonds, the weak hydrogen bonds gain an importance

The crystal structures of brucinium hydrogen N-benzoyl-D-aspartate tetrahydrate (1), brucinium N-benzoyl-D-asparaginate trihydrate (2), brucinium N-tert-butoxycarbonyl-L-alaninate 2-propanol solvate hydrate (3) and brucinium N-tert-butoxycarbonyl-L-prolinate ethanol solvate hydrate (4) were determined. In all crystals under investigation, the brucinium cations form corrugated layers with anions and solvent molecules between them. Our investigations concerning the nature of the brucine layers show that such self-assemblies provide optimally appropriate surfaces for interactions in the hydrophilic environment from which the crystals of brucinium salts were usually grown. In an effort to obtain the most appropriate surfaces, weak hydrogen bonds gain in importance. This suggestion seems to be confirmed by the presence of the same pattern of the weak hydrogen bonds that one can observe in many crystals containing brucine (molecular/ionic).

Structure, phase transitions and molecular motions in 4-aminopyridinium perchlorate

The crystal structure of the 4-aminopyridinium perchlorate (4-apyH)ClO4 has been determined at 100 K by means of x-ray diffraction as monoclinic, with space group P 21, with Z = 8. The crystal undergoes two structural phase transitions: one of first-order type, reversible, at 241/243 K (on cooling/heating respectively) and one of weakly first-order type, irreversible, at 277 K (on heating). The crystal dynamics is discussed on the basis of the temperature dependence of the 1 H nuclear magnetic resonance second moment (M2) and spin–lattice relaxation time T1. Both phase transitions are interpreted in terms of the changes in the motional state of (4-apyH)+ cations and ClO4− anions. The dielectric dispersion studies disclose a relaxation process over the high-temperature phase (above 241 K) in the audio-frequency region. The dielectric results are described by a Cole–Cole equation. The title crystal reveals pyroelectric properties below 241 K. The ferroelastic domain structure of (4-apyH)ClO4 is observed over the whole temperature range studied.