Coordination supramolecular structures

Supramolecular coordination ensembles with d-metal ions directly incorporated into their structures are the subject of the present review. Diversity of such structures considerably exceeds that of purely organic supramolecules due to inclusion of additional polyvalent metal atoms (totally sixty) with diverse coordination geometry. Such metal-containing constructions are generated by self-assembling and (or) by templating, as 2D and 3D geometric figures (polygons and polyhedra) and “furniture” constructions (ladders, racks, grids) together with helicates, interwoven species and metallodendrimers as combinations of 1D coordination compounds. Besides, is presented a numerous of coordination polymers and supramolecular crystal lattices as infinite structures.     

Azomethyne derivatives of 1,3-benzothiazine 1,1-dioxide

The Schiff's bases 2-alkyl-4-oxo-3,4-dihydro-2H-1,2-benzothiazine 1,1-dioxides have been synthesized for the first time, their structures in solution and in the crystalline state and their ability to form complexes have been investigated. The unusual condensation reaction of 1,2-benzothiazine 1,1-dioxide with ethyl orthoformate and 4-aminoantipyrine has been observed.     

Experimental and theoretical study of the basicity of azoles and their analogs

The thermodynamic ionization constants of 30 imidazole, pyrazole, triazole, and thiazole derivatives and their structural analogs were determined by potentiometric titration in acetonitrile. The effect of individual structural factors on the basicity of the azole molecules is discussed. It is demonstrated that the best theoretical basicity index is the magnitude of the electrostatic energy of interaction () of the unshared pair of the nitrogen atom being protonated with the system of charges. The values were calculated by means of the MO self-consistent-field (MO SCF) method with the Pariser-Parr-Pople approximation and by the simple Hückel method. The pK_a- correlation equations obtained make it possible to predict the pK_a values of azoles with an average accuracy of 0.5 pK_a units for acetonitrile solutions and 0.3 units for aqueous solutions.Communication XI of the series Basicity and Structure of Azomethines and Their Structural Analogs. See [1] for communication X.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 552–557, April, 1972.     

Reaction of 3,4-diaminofurazan with carbonyl compounds and their metal complexes

It is shown that when 3,4-diaminofuranzan reacts with formic acid under various conditions there is, along with the mono- and diformylation, an intermolecular reaction leading to a polymeric compound. The diamine under consideration forms a monoazomethine with salicylaldehyde but a bis (azomethine) complex with the salicylaldehydate of divalent nickel.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 666–669, May, 1986.     

Alkalli Metal Complexes with <Emphasis Type="Italic">N</Emphasis>-(4′-Benzo-15-Crown-5)-2-(Amino-<Emphasis Type="Italic">N</Emphasis>-tosyl)-phenylaldimine

Complexes of Li, Na, and K with N-(4′-benzo-15-crown-5)-2-(amino-N-tosyl)-phenylaldimine (L) are synthesized and their IR spectra are studied with assignment of the basic vibration frequencies of the ligand and complexes. The conformation states of macrocycles in the title complexes are analyzed. The macrocycle conformation in complexes of L with the Li, Na, and K salts is not influenced by the nature of a metal or acido ligands. The structures of the synthesized compounds are suggested on the basis of the spectral and elemental analysis data.__________Translated from Koordinatsionnaya Khimiya, Vol. 31, No. 7, 2005, pp. 512–517.Original Russian Text Copyright © 2005 by Ivanova, Dorokhov, Pyatova, Bicherov, Burlov, Garnovskii, Tsivadze.     

Direct addition of alcohols to organonitriles activated by ligation to a platinum(IV) center

Treatment of trans-[PtCl(4)(RCN)(2)] (R = Me, Et) with R'OH (R' = Me, Et, n-Pr, i-Pr, n-Bu) at 45 degrees C in all cases allowed the isolation of the trans-[PtCl(4)[(E)-NH=C(R)OR'](2)] imino ester complexes, while the reaction between cis-[PtCl(4)(RCN)(2)] and the least sterically hindered alcohols (methanol and ethanol) results in the formation of cis-[PtCl(4)[(E)-NH=C(R)OR'](2)] (R/R' = Me/Me) or trans-[PtCl(4)[(E)-NH=C(Et)OR'](2)] (R' = Me, Et), the latter being formed via thermal isomerization (ROH, reflux, 3 h) of the initially formed corresponding cis isomers. The reaction between alcohols R'OH and cis-[PtCl(4)(RCN)(2)] (R = Me, R' = Et, n-Pr, i-Pr, n-Bu; R = Et; R' = n-Pr, i-Pr, n-Bu), exhibiting greater R/R' steric congestion, allowed the isolation of cis-[PtCl(4)[(E)-NH=C(R)OR'][(Z)-NH=C(R)OR']] as the major products. The alcoholysis reactions of poorly soluble [PtCl(4)(RCN)(2)] (R = CH(2)Ph, Ph) performed under heterogeneous conditions, directly in the appropriate alcohol and for a prolonged time and, for R = Ph, with heating led to trans-[PtCl(4)[(E)-NH=C(R)OR'](2)] (R = CH(2)Ph, R' = Me, Et, n-Pr, i-Pr; R = Ph, R' = Me) isolated in moderate yields. In all of the cases, in contrast to platinum(II) systems, addition of R'OH to the organonitrile platinum(IV) complexes occurs under mild conditions and does not require a base as a catalyst. The formed isomerically pure (imino ester)Pt(IV) complexes can be reduced selectively, by Ph(3)P=CHCO(2)Me, to the corresponding isomers of (imino ester)Pt(II) species, exhibiting antitumor activity, without change in configuration of the imino ester ligands. Furthemore, the imino esters NH=C(R)OR' can be liberated from both platinum(IV) and platinum(II) complexes [PtCl(n)[H=C(R)OR'](2)] (n = 2, 4) by reaction with 1,2-bis(diphenylphosphino)ethane and pyridine, respectively. All of the prepared compounds were characterized by elemental analyses (C, H, N), FAB mass spectrometry, IR, and (1)H, (13)C[(1)H], and (195)Pt (metal complexes) NMR spectroscopies; the E and Z configurations of the imino ester ligands in solution were determined by observation of the nuclear Overhauser effect. X-ray structure determinations were performed for trans-[PtCl(4)[(E)-NH=C(Me)OEt](2)] (2), trans-[PtCl(4)[(E)-NH=C(Et)OEt](2)] (10), trans-[PtCl(4)[(E)-NH=C(Et)OPr-i](2)] (11), trans-[PtCl(4)[(E)-NH=C(Et)OPr-n](2)] (12), and cis-[PtCl(4)[(E)-NH=C(Et)OMe](2)] (14). Ab initio calculations have shown that the EE isomers are the most stable ones for both platinum(II) and platinum(IV) complexes, whereas the most stable configurations for the ZZ isomers are less stable than the respective EZ isomers, indicating an increase of the stability on moving from the ZZ to the EE configurations which is more pronounced for the Pt(IV) complexes than for the Pt(II) species.     

Novel reactivity mode of hydroxamic acids: a metalla-pinner reaction

The reaction between the nitrile complex trans-[PtCl(4)(EtCN)(2)] and benzohydroxamic acids RC(6)H(4)C([double bond]O)NHOH (R = p-MeO, p-Me, H, p-Cl, o-HO) proceeds smoothly in CH(2)Cl(2) at approximately 45 degrees C for 2-3 h (sealed tube) or under focused 300 W microwave irradiation for approximately 15 min at 50 degrees C giving, after workup, good yields of the imino complexes [PtCl(4)[NH[double bond]C(Et)ON[double bond]C(OH)(C(6)H(4)R)](2)] which derived from a novel metalla-Pinner reaction. The complexes [PtCl(4)[NH[double bond]C(Et)ON[double bond]C(OH)(C(6)H(4)R)](2)] were characterized by elemental analyses (C, H, N), FAB mass spectrometry, and IR and (1)H and (13)C[(1)H] spectroscopies, and [PtCl(4)[NH[double bond]C(Et)ON[double bond]C(OH)(Ph)](2)] (as the bis-dimethyl sulfoxide solvate), by X-ray single-crystal diffraction. The latter disclosed its overall trans-configuration with the iminoacyl species in the hydroximic tautomeric form in E-configuration which is held by N[bond]H...N hydrogen bond between the imine [double bond]NH atom and the hydroximic N atom.     

New octahedral Zn<Superscript>II</Superscript> and Cd<Superscript>II</Superscript> complexes based on azo derivatives and azomethines of pyrazole-5-thione

New metal chelates of Zn^II and Cd^II (ML₂) based on (4Z)-3-methyl-1- phenyl-5-thioxo-1,5-dihydro-4-H-pyrazol-4-one quinolin-8-ylhydrazone (HL¹) and (4Z)-5- methyl-2-phenyl-4-[(quinolin-8-ylimino)methyl]-2,4-dihydro-3H-pyrazole-3-thione (HL²) were synthesized. The structures of the metal chelates were studied by EXAFS and NMR (¹H, ¹³C, and ¹¹¹Cd) spectroscopy. The structure of the Cd(L¹)₂ complex was established by X-ray diffraction analysis. The complexes have pseudooctahedral structures with the N₄S₂ ligand environment.__________Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 623–629, March, 2005.     

Femtosecond vibrational dynamics of self-trapping in a quasi-one-dimensional system

We have directly time resolved the lattice motions associated with the formation of the self-trapped exciton in the quasi-one-dimensional system [Pt(en)(2)] [Pt(en)2Br2];(PF6)(4) ( en = ethylene-diamine, C2H8N2), using femtosecond impulsive excitation techniques. A strongly damped, low-frequency wave packet modulation at approximately 110 cm(-1) accompanies the formation of the self-trapped exciton on a approximately 200 fs time scale following excitation of the intervalence charge-transfer transition. Coherent oscillations at the ground state vibrational frequency and its harmonics are also detected.