Synthesis, characterization and conformational analysis of chloro-bis(glycylglycinate)germanium(IV) chloride

Chloro-bis(glycylglycinate)germanium(IV) chloride, [Cl(glygly)2Ge]Cl, was synthesized and characterized in the solid state by elemental analysis, thermogravimetry and infrared spectroscopy. Solution studies were also performed by 1H-NMR and 13C-NMR in dimethylsulfoxide (DMSO-d6) and by electric conductivity. The structural determination of the complex and the interpretation of the spectroscopic results were performed by employing an integrated computational approach, based on a systematic conformational search analysis on the [Cl(glygly)2Ge]+ ion performed by the Systematic Conformational Search Algorithm (SCSA) code, working at the hybrid B3LYP/6-31G(d,p) level. The combination of experime…

Information science and computational methods in the modern chemistry education

Nucleophilic attack by 2-pyridylpalladium(II) and platinum(II) complexes on the organic chlorides ClCH2R (R  COMe, CN, Ph, Cl)

Abstract The 2-pyridyl complexes trans-[MCl(C5H4NC2)(PPh3)2] (M = Pd, 1a; M = Pt, 1b), [MCl(C5H4NC2)(dppe)] (M = Pd, 2a; M = Pt, 2b) and [M(dmtc)(C5H4NC2) (PPh3)] (M = Pd, 3a; M = Pt,3b) react with the chlorides ClCH2R(R  COMe, CN, Ph) to give cationic products containing the 2-pyridylium ligands (1-CH2R)C5H4NC2. The rate of nucleophilic displacement of the chloride ion from ClCH2R depends on the central metal (Pt > Pd), on the coordination geometry (1 ~ 3) and on the substituent R (COMe > CN > Ph for the reactions with 3b). Like 1b and 2b, complex 3b also reacts with dichloromethane to give [Pt(dmtc){(1-CH2Cl)C5H4NC2}(PPh3)]+. The reaction of the binuclear compound [{PdCl(μ-C5H4NC2,…

Organometallic complexes with biological molecules. XI. Solid state and in vivo investigations of some diorganotin(IV)-chloramphenicol and cycloserine derivatives

Abstract Diorganotin(IV) derivatives of chloramphenicol, {=D-(-)threo-2,2-dichloro-N-[ β -hydroxy- α -(hydroxymethyl)- β -(4-nitrophenyl)ethyl]acetamide (=Hchloramph)}, and D-cycloserine, {=(R)-4-amino-3-isoxazolidone [=Hcyclos]} have been prepared. The stoichiometries of the obtained compounds were R 2 SnClantib and R 2 Snantib 2 (antib −1 =chloramph −1 , R=methyl and phenyl; antib −1 =cyclos −1 , R=methyl). The solid state configuration of the complexes was investigated by I.R. and Mossbauer spectroscopy, from which structural hypotheses were inferred. In particular, the experimental data suggested monomer structures both for R 2 Sn(IV)Clchloramph and R 2 Sn(IV)chloramph 2 , in which chlo…

Complessi del germanio tetracloruro con basi di Schiff:sintesi e caratterizzazione

COMPLESSI DEL GERMANIO TETRACLORURO CON BASI DI SCHIFF: SINTESI E CARATTERIZZAZIONE Alberta Fontana Dipartimento di Chimica Inorganica e Analitica S. Cannizzaro. Universita' di Palermo Per reazione della base di Schiff PYAP con il GeCl4 in metanolo nel rapporto Ge/PYAP di 1:2 si ottengono due composti :il composto “a” (GeC28H24N4O6 )(colore arancio) e”b” ( GeC28H28N4O7Cl2 ) ( colore rosso). Il composto a è stato ottenuto in presenza di MeONa . Questi composti sono stati caratterizzati da analisi centesimale, misure I.R., H1NMR , conducibilità e T.G. Da un’analisi effettuata sugli spettri IR dei complessi e del legante si nota la scomparsa a 1234 cm1 della banda attribuibile all’OH fenolico1…

Stereo and regioselectivity in the phenylation of cationic allylpalladium(II) α-diimine complexes by tetraphenylborate anion

The reaction of the cationic complex [Pd(4-methoxy-1,3-η3-cyclohexenyl)(py-2-CHNC6H4OMe-4)]+ (1) with BPh4− in the presence of fumaronitrile yields trans-3-methoxy-6-phenylcyclohexene (2a) and trans-4-methoxy-3-phenylcyclohexene (2b), in ca. 1 : 1 molar ratio. The trans stereochemistry of these products implies that the phenylation of the allyl ligand involves prior transfer of a phenyl group from BPh4− to the metal, followed by reductive coupling of the organic moieties. In the reactions of [Pd(η3-1,1-R1,R2-C3H3)(NN′)]+ (3) [NN′ 4-MeOH4C6NCHCHNC6H4OMe-4; py-2-CHNR (R  C6H4OMe-4, Me, or CMe3), 2,2′-bipyridine (bipy); R1  H, R2  Ph, Me; R1  R2  Me; with BPh4− in the presence of …

CO on Nickel: some computational insights about steric hindrance in loaded surfaces

SIMPLE MODEL OF GERMANIUM-PEPTIDE INTERACTIONS: BIS-GLYCYLGLYCINE-GERMANIUM-CHLORIDE

Itinerari archeologici della Sicilia nord-occidentale:Himera.Caratterizzazione di reperti ceramici provenienti dalla necropoli di Pestavecchia

Itinerari archeologici della Sicilia occidentale: Himera. Studio di reperti ceramici

Synthesis and chemico-physical characterization of tin(IV) complexes with some crown ethers

Abstract Some neutral adducts of diorganotin(IV) perchlorates and thiocyanates with three crown-ethers have been synthesised; they are of the type Me 2 SnX 2 L m · n H 2 O where m = 1 or 2, n = 2 or 4, X = ClO 4 or NCS, and L = 18-crown-6, 15-crown-5, and 12-crown-4. The values for m and n have been correlated with the coordinating ability of the two anions and with the steric hindrance by the crown ether molecules. From infrared and Mossbauer data, an octahedral coordination geometry is proposed for all the complexes. The Mossbauer parameters are discussed in terms of the electronegativity of the ligands on the tin(IV) center and of the distortions produced in the coordination polyhedra by…

CONFORMATIONAL ANALYSIS AND DFT-GIAO 13CNMR CHEMICAL SHIFT CALCULATION OF DIMETHYLTIN(IV)-D-RIBONATE COMPLEX

Organometallic nucleophiles.A mechanistic study of halide displacement at saturated carbon by 2- and 4-pyridyl complexes of palladium (II) and platinum (II)

Abstract The reactions of the 2- and 4-pyridyl complexes [MX(C 5 H 4 N C n )(dppe)] and trans -[MX(C 5 H 4 N C n )(PPh 3 ) 2 ] (M  Pd, Pt; X  Cl, Br; n = 2, 4)- involving halide displacement from the organic halides XCH 2 R (X  Cl, Br; R  CN, Ph, CH  CH 2 ) by the pyridyl nitrogen have been studied kinetically by conductivity in acetone or acetonitrile at 25°C. The kinetic data fit the second-order rate law rate k 2 [XCH 2 R][complex], in agreement with an S N 2 process at saturated carbon. The higher rates are displayed by the 2-pyridylplatinum derivatives with X  Br in both the metal complex and the organic halide. The higher nucleophilic power of the 2-pyridyl complexes compare…

Mechanism of oxidative allyl transfer from allylic ammonium cations to palladium(0) α-diimine complexes

Abstract The palladium(0) complex [Pd(η2-fn)(NN′)] (1, fn = fumaronitrile; NN′ = C5H4N-2-CH=NC6H4OME-4) reacts slowly and reversibly with A +  CH 2  CH=CH 2 (2a, A = NEt 3 ; 2 b , A = C 5 H 5 N ) to yield the cationic η3-allypalladium(II) derivative [ Pd (η[ 3 - C 3 H 5 )( N  N ′)] + (3) the free amine A and fn. The equilibrium constant Ke is (2.6 ± 0.1) × 10−3 for 2a and 1.0 ± 0.4 for 2b. Kinetic studies of these oxidative allyl-transfer reactions show that the rates increase with increasing concentration of 2 and with decreasing concentration of fn. A stepwise mechanism is proposed which involves slow and reversible displacement of fn by 2 to give a labile intermediate [ Pd (η 2 - CH…

Computational Aspects in heterogeneous nano-catalysis

A concise description of the metods,which we have developed and employed in studying, by first principle computational models, the field of the heterogeneous catalysis is reported here along with obtained results. In this frame, the main characterstics of the time dependent Monte Carlo modelling are illustrated. The importance of using Monte Carlo models supported by high level quantum-mechanical information, to find alternative lines in studying heterogeous catalysis and designing new catalytic experiments and applications at nanoscopic level, is stressed. Technical details are illustrated, considering applications for the hydrogenation of organic substrates on metal catalysts in two-and t…

Cadmium(II) complexes of cytosine

Complexes of cadmium(II) with cytosine obtained from aqueous or physiological solutions at room temperature are reported. The complexes were characterized by spectroscopic, conductometric,1H-NMR, and13C-NMR measurements and also by thermogravimetry.

Metodi quantomeccanici e Monte Carlo applicati a sistemi nanostrutturati