G.C. Stocco

Mössbauer spectroscopy of mono-organotin(IV) derivatives

Abstract The Mossbauer parameters isomer shift, δ, and quadrupole splitting, ΔE, of mono-organotin compounds insofar investigated have been collected and tabulated. It is demonstrated that isomer shifts consistently depend on ligand electronegativities and coordination numbers, from which it is deduced that RSn IV behave much more as Sn IV rather than R 2 Sn IV and R 3 Sn IV derivatives. The changes of δ for RSn IV are then interpreted by hypotheses analogous to those advanced for Sn IV and its adducts and complexes. It is also inferred that in RSn IV compounds there is a consistent s-character in all tin-ligand atom bonds.

Synthesis and characterization of complexes of trialkyl- and triarylphosphine gold(I) with thiolated purines and pyrimidines: a class of bifunctional compounds with potential antitumor activity

Abstract New complexes of the type R 3 PAuL or (R 3 PAu) 2 (μ-L) where R=ethyl or phenyl and L=6-thioguanine, 2, 6- dithioxanthine, 2, 4-dithiouracil and/or dithioerythritol have been prepared. These complexes have been identified by using elemental analysis, 1 H, 13 C and 31 P NMR spectroscopy. The structures have been proposed based on these spectroscopic studies. Sulfur appears to be the binding site in disubstituted complexes of 2, 4-dithiouracil and 1, 4-dithioerythritol, while the phosphine gold( I ) moieties appear to be S and N bonded in 2, 6-dithioxanthine and 6-thioguanine. The potential use of these complexes as antitumor drugs is discussed.

Organometallic complexes with biological molecules: VII. Dialkyl- and trialkyl-tin (IV)[meso-tetra(4-carboxyphenyl)porphinate] derivatives : Solid-state, solution-phase structural aspects and in vivo effects

The synthesis, the structural features and the in vivo biological activity of diorganotin(IV) and triorganotin(IV) derivatives of [meso-tetra(4-carboxyphenyl)porphine] (H 4 TPPC) are reported. Derivatives with general formula (R 2 Sn) 2 TPPC and (R 3 Sn) 4 TPPC (R=Me, Bu, and Ph) were obtained, and the main information extracted from the infrared and Mossbauer spectral data, in the solid state, was in favor of the occurrence of five-coordinated tin(IV) atoms, in a polymeric trigonal-bipyramidal configuration, attained through two differently coordinated, estertype and chelating respectively, carboxylate anions in [R 2 Sn] 2 TPPC, while in [Alk 3 Sn] 4 TPPC five-coordination of the tin(IV) atom is reached through bridging carboxylate groups. 1 H and 13 C NMR spectra, in DMSO-d 6 or CDCl 3 suggested that the soluble derivatives, at room temperature or at 342K, were present in solution as simple monomers. The interactions of (trimethyltin) 4 [meso-tetra(4-carboxyphenyl)porphinate] (TMTPPC) and (tributyltin)4[mesa-tetra(4-carboxyphenyl)porphinate] (TBTPPC) with Bluescript KS(+) plasmid and cultured 3T3 fibroblasts were studied. Both compounds have a clear inhibitory effect on the growth of cultured mouse embryonal fibroblasts (NIH-3T3), TBTPPC being much more active. No evidence was found, however, for DNA cleavage by the compounds at molar ratios as high as 1:10 (TMTPPC, TBTPPC/DNA base pairs). According toour observations, the cytotoxicity of TBTPPC and TMTPPC does not seem to be besed on direct interation with DNA

Spectroscopic characterization and biological activity of L-methionyl-L histidinato complexes of R2Sn(IV) ions (R = Me, nBu, Ph) and X-ray structure of Me2SnMetHis ˙ 0.5MeOH

Complexes of L-methionyl-L-histidine (H2MetHis) with R2Sn(IV) ions (R = Me, nBu, Ph) have been synthesized. The crystal and molecular structures of Me2SnMetHis·0.5MeOH have been determined by X-ray diffraction. The title compound contains two crystallographically independent molecular units possessing the same trigonal-bipyramidal geometry at tin, each dimethyltin(IV) moiety being coordinated by the terminal amino nitrogen, deprotonated peptide nitrogen and terminal carboxylate group, neither the imidazole nor thioether groups being involved in bonding. IR spectroscopy was used to probe the structure of the complexes in the solid state, and the structure in solution (CD3OD) was assessed by 1H and 13C NMR. Me2Sn(IV)dipeptide complexes appear to be undissociated and to retain a pentacoordinated structure. Rotamer population of C-terminal histidine was determined by analysis of vicinal coupling constants and side-chain orientations have been interpreted with a view to potential applications of the compounds as recognition agents. Biological activity was tested on Ascidian embryos of Ciona intestinalis at different stages of development. Copyright

Synthesis, characterization, crystal structures and in vitro antistaphylococcal activity of organotin(IV) derivatives with 5,7-disubstituted-1,2,4-triazolo(1,5-a)pyrimidine

New organotin(IV) complexes of 5,7-ditertbutyl-1,2,4-triazolo[1,5-a]pyrimidine (dbtp) and 5,7-diphenyl-1,2,4-triazolo[1,5-a]pyrimidine (dptp) with 1:1 and/or 1:2 stoichiometry were synthesized and investigated by X-ray diffraction, FT-IR and (119)Sn Mössbauer in the solid state and by (1)H and (13)C NMR spectroscopy, in solution. Moreover, the crystal and molecular structures of Et(2)SnCl(2)(dbtp)(2) and Ph(2)SnCl(2)(EtOH)(2)(dptp)(2) are reported. The complexes contain hexacoordinated tin atoms: in Et(2)SnCl(2)(dbtp)(2) two 5,7-ditertbutyl-1,2,4-triazolo[1,5-a]pyrimidine molecules coordinate classically the tin atom through N(3) atom and the coordination around the tin atom shows a skew trapezoidal structure with axial ethyl groups. In Ph(2)SnCl(2)(EtOH)(2)(dptp)(2) two ethanol molecules coordinate tin through the oxygen atom and the 5,7-diphenyl-1,2,4-triazolo[1,5-a]pyrimidine molecules are not directly bound to the metal center but strictly H-bonded, through N(3), to the OH group of the ethanol moieties; Ph(2)SnCl(2)(EtOH)(2)(dptp)(2) has an all-trans structure and the C-Sn-C fragment is linear. On the basis of Mössbauer data, the 1:2 diorganotin(IV) complexes are advanced to have the same structure of Et(2)SnCl(2)(dbtp)(2), while Me(2)SnCl(2)(dptp)(2) to have a regular all-trans octahedral structure. A distorted cis-R(2) trigonal bipyramidal structure is assigned to 1:1 diorganotin(IV) complexes. The in vitro antibacterial activities of the synthesized complexes have been tested against a group of reference pathogen micro-organisms and some of them resulted active with MIC values of 5μg/mL, most of all against staphylococcal strains, which shows their inhibitory effect.

Organoelement derivatives of steroids: synthesis and structural characterization of diorganotin chloride adducts of hormones

Abstract Ten new diorganotin dichloride adducts of hormones of the type R 2 SnCl 2 ·2L [where R = Me, Et, n-Bu, Oct and Ph; L = 4-androsten-17s-ol-3-one ( A ); 5-androsten-3s-ol-17-one ( B ); 4-androsten-17α- methyl-17s-ol-3-one ( C ) and 3,17-dihydroxy-5- pregnene-20-one ( D )] have been prepared and characterized at 297 K and 223 K. Spectroscopic measurements (IR; Raman; 1 H, 13 C, 119 Sn NMR) suggest the dissociation or fast ligand exchange in solution at 297 K. Hexa-coordinated adducts with bonding through carbonyl oxygen and trans -R groups in octahedral geometry are formulated at 223 K.

Complexes of (CH3)2AuIII: synthesis, PMR and IR spectra

Abstract The syntheses and reactivity of dimethylgold(III) complexes with multidentate ligands as TRIPHOS (i.e., 1,1,1-tris(diphenylphosphinomethyl)ethane) and TREN (i.e. 2,2′,2″-triaminotriethylamine) have been examined. I.r. spectra for the compounds in the solid state, conductivity and PMR data for solutions, lead to the assignment of an ionic formula [CH 3 ) 2 Au TRIPHOS] + [(CH 3 ) 2 AuCl 2 ] − where the gold(III) atoms are presumably four-coordinate. The complex (CH 3 ) 2 AuCl TREN in DMSO solution undergoes a reductive elimination reaction, as found for analogous dimethylgold(III) derivatives.

Complexes of organometallic compounds : XL. organolead(IV) azido and mixed azido—thiocyanato complex anions

Abstract Tetraphenylarsonium and tetramethylammonium salts of the complex anions Ph 3 Pb(N 3 ) − 2 , Ph 3 Pb(N 3 )(NCS) − , Ph 2 Pb(N 3 ( 2 − 4 )) and Ph 2 Pb(N 3 )(NCS) − 2 have been prepared and characterized. Infrared spectra and solution conductance data are reported. Possible configurations of the complex anions are discussed.

119Sn mössbauer, IR, 1H NMR spectroscopic and thermal decomposition studies on organotin(IV) adducts with glycylglycine

Abstract The complexes R 2 SnCl 2 ·(H 2 glygly), (H 2 glygly = glycylglycine) (R = Me, Bu n , Oct n , Ph) and RSnCl 3 ·(H 2 glygly)

An infrared study of organothallium thiocyanates

Abstract Some structural aspects of the organothallium(III) thiocyanates R 2 TlCNS (R = Me, Ph).[Ph 4 As][Me 2 Tl(CNS) 2 ] and Phtl(CNS) 2 have been studied by IR spectroscopy. From the frequencies of the NCS group vibrations in the solids, and the integrated intensity of the C≡N stretching absorption in solution, it was ascertained that the diorganothallium derivatives are isothiocyanates with a certain amount of ionic character in the TlNCS bonds, whereas PhTl(CNS), is essentially a TlSCN bonded compound. Apparently both solid Me 2 TlCNS and [Ph 4 As][Me 2 Tl(CNS) 2 ] do not show IR active ν s (TlC 2 )bands. The compound Me 2 TlCNS displays a double ν as (TlC 2 band, from which the presence in the solid of non-equivalent Me 2 Tl III moieties could be inferred. Possible configuration of the dimethylthallium derivatives are discussed.