Soon-Beng Teo

Inner coordination sphere tin(IV) complexes with some O,N,N-terdentate {N-(2-hydroxybenzaldehyde)-1-amino-2-phenyleneimine and N-(2-hydroxy-1-naphthaldehyde)-1-amino-2-phenyleneimine} and O,N,N,O-quadridentate {N,N′-bis(2-hydroxybenzaldehyde)-1,2-phenylenediimine and N,N′-bis(2-hydroxy-1-naphthaldehyde)-1,2-phenylenediimine} Schiff bases

Abstract From the reactions of SnCl4 with organotin(IV) chlorides (RSnCl3, R2SnCl2 and R3SnCl, where R = Bu, Me and Ph) with N-(2-hydroxybenzaldehyde)-1-amino-2-phenyleneimine, N-(2-hydroxyl-1-naphthaldehyde)-1-amino-2-phenyleneimine, N,N′-bis(2-hydroxybenzaldehyde)-1,2-phenylenediimine and N,N′-bis(2-hydroxy-1-naphthaldehyde)-1,2-phenylenediimine a series of complexes have been synthesized and characterized, respectively, by microanalytical, IR, and 1H NMR spectroscopic methods. The Ph2SnCl2 reacted with N-(2-hydroxy-1-naphthaldehyde)-1-amino-2-phenyleneimine giving Ph2Sn(NAPPDI) [where NAPPDI = deprotonated N,N′-bis(2-hydroxy-1-naphthaldehyde)-1,2-phenylenediimine], wherein the former Schiff base exhibit a facile intramolecular CN bond cleavage and intermolecular CN bond formation.

Synthesis and crystal structure of di-n-butylbis(2-amino-5-chlorobenzoato)tin(IV)

Reaction of di-n-butyltin oxide with 2-amino-5-chlorobenzoic acid in 1:2 stoichiometry yields the title compound which crystallizes as the six-coordinate diorganotin dicarboxylate monomer. The crystal structure of the compound reveals the tin atom situated on a crystallographic two-fold axis in a skew-trapezoidal bipyramid geometry. The trapezoidal plane is defined by two asymmetrically chelating carboxylate groups; Sn-O bonds are 2.123(4) and 2.484(5) Angstrom and the C-Sn-C angle is 141.7(6)degrees: The nitrogen atom of the amino group of the carboxylate ligand does not participate in any significant interactions with the tin atom.

SYNTHESIS, CRYSTAL STRUCTURE AND BIOLOGICAL ACTIVITY OF BIS(ACETONE THIOSEMICARBAZONE-S)DICHLORODIPHENYLTIN(IV)

The reaction between diphenyltin(IV) dichloride and thiosemicarbazide using acetone–ethanol as solvent resulted in the formation of bis(acetone thiosemicarbazone-S)dichlorodiphenyltin(IV), SnPh 2 Cl 2 (atsc) 2 . The crystal structure determination of the compound revealed it to be a monomeric six-co-ordinated organotin(IV) complex. Each of the two atsc functions as a monodentate ligand, co-ordinating to the tin atom through the sulfur atom and conferring a distorted-octahedral geometry upon the tin. The Sn–S bond length is 2.712(1) A. The antifungal activity of the complex, atsc and SnPh 2 Cl 2 against four plant pathogens has been evaluated. The complex displays marked fungitoxicity against these fungi and is more fungitoxic than free atsc and SnPh 2 Cl 2 . It has also shown significant cytotoxicity against human colon adenocarcinoma, breast adenocarcinoma, hepatocellular carcinoma and acute lymphoblastic leukaemia.

The preparation and X-ray crystal structures of bis (4R-oxazolidine-4'-carboxylato) copper (II) (R=methyl, phenyl)

Abstract The base-catalyzed condensation reactions of formaldehyde with the copper(II) chelates of α-alanine and C-phenylglycine result in the formation of bis(4R-oxazolidine-4′-carboxylato)copper(II) where R = methyl and phenyl respectively. The 4-methyl complex, C 10 H 20 N 2 O 8 Cu, crystallizes in the monoclinic space group P 2 1 / n with a = 9.141(2), b = 7.335(3), c = 11.112(3) A, β = 103.87(2)° and Z = 2. The structure has been refined to R = 0.026 and R w = 0.031 based on 749 independent reflections collected, 651 used. The geometry about copper is essentially a (4 + 2)-elongated octahedral structure. The 4-phenyl derivative, C 20 H 20 N 2 O 6 Cu, crystallizes in the monoclinic space group P 2 1 / c with a = 11.939(4), b = 8.887(2), c = 8.611(3) A, β = 95.61(3)° and Z = 2. Refinement of the structure converged to R = 0.062 and R w = 0.071 based on 1003 reflections collected and 865 used. The structure of the 4-phenyl complex resembles that of the 4-methyl derivative and differs mainly from the latter in being anhydrous.

Inner sphere complexes derived from the coordinate interactions of tin(iv) isothiocyanate moieties with 1-[(4-methylphenylimino)methyl]-2-phenol. crystal structure of diisothiocyanatodimethylbis 1[(4-methylphenylimino)methyl]-2-phenoltin(iv), Me2Sn(NCS)2 · [HOC6H4CH : NC6H4CH3]2

Abstract A series of neutral complexes derived from the reactions of Sn(NCS) 4 , PhSn(NCS) 3 and R 2 Sn(NCS) 2 (R = Me and Ph) with [1-[(4-methylphenylimino)methyl]-2-phenol] have been synthesized. An X-ray crystal structural study of the diisothiocyanatodimethyltin(IV) derivative has been performed and all synthesized compounds were characterized by IR, 1 H and 13 C NMR spectroscopies. All the complexes exhibit octahedral geometry with tin-oxygen (Sn-O) coordination.

SYNTHESIS AND STRUCTURAL STUDIES OF SOME METAL(II) COMPLEXES OF 5-METHYLOXAZOLIDINE-4-CARBOXYLIC ACID

Abstract The reactions of formaldehyde with the metal(II) chelates of L threonine (metal = copper, nickel, cobalt and zinc) result in the formation of the metal(II) complexes of 5-methyloxazolidine-4-carboxylic acid. The copper(II) complex, C 10 H 20 N 2 O 8 Cu, is obtained from the recrystallization of its 3-hydroxymethyl derivative, C 12 H 24 N 2 O 10 Cu, which initially forms. C 10 H 20 N 2 O 8 Cu crystallizes in the orthorhombic space group P 2 1 2 1 2 1 with a =8.166(1), b =8.936(1), c =20.463(5) A and Z =4. The structure has been refined to R =0.021 and R w =0.021 based on 1444 reflections with l > 2.5σ( l ). The geometry about copper is based on a square pyramid with a coordinated water in the apical position. The synthesized compounds are characterized by microanalysis, magnetic and thermal data as weil as examinations of their electronic and infrared spectra.

Novel hydroxo bidentate carboxylate bridging in diorganotin(IV) carboxylate complex Synthesis and crystal structure of μ-hydroxo-μ-trichloroacetato-O,O′-bis (trichloroacetato-O)-bis[dibutyltin(IV)], Sn2(C4H9)4(O2CCCl3)3(OH)

Abstract The crystal structure determination of the title compound reveals that it appears to be entirely novel. It does not contain a stannoxane ring, but both Sn atoms are held together by hydroxide and acetate bridges, forming a six-membered ring. Both Sn atoms occupy distorted trigonal bipyramidal environments with one bidentate bridging trichloroacetate group and one monodentate trichloroacetate group in axial positions, whilst the butyl groups and the bridging OH group lie in the equatorial plane.

Reaction of Bis(β-Alaninato)Copper(II) with Formaldehyde and Ammonia: X-Ray Crystal Structure of [3N,7N-(1,3,5,7-Tetraazabicyclo-[3.3.1]Nonyl)-DI-3-Propionato]Copper(II)

Abstract The reaction of bis(β-alaninato)copper(II) with formaldehyde and ammonia over the pH range 6.6-8.8 results in the formation of [3N,7N-(1,3,5,7-tetraazabicyclo[3.3.1]nonyl)-di-3-propionato]copper(II) trihydrate, C11H24N4O7Cu, which crystallizes in the monoclinic space group P2t/c with a = 10.903(2), b = 7.340(2), c = 19.435(3) A, β = 98.27(1)[ddot] and Z = 4. The structure has been refined to R = 0.040 and R w = 0.044 based on 2655 reflections with I ≥ 2.5σ(I). The chelate molecules are linked in chains by a carbonyl oxygen to copper interaction which results in square pyramidal coordination of the copper ion.

The structures of the adducts formed from organotin moieties and 1-[(4-methoxyphenylimino)methyl]-2-naphthol. Crystal structure of chloro-trimethyl[1-[

Abstract A series of adducts resulting from the coordinative interaction of RSnCl 3 , R 3 SnCl 2 and R 3 SnCl (R  Me and Ph) with 1-[(4-methoxy

Synthesis and crystal structure of the tetrabutylbis(thiophene gloxylato) distannoxane dimer, {[(C4H9)2SnO2CC(O)C4H3S]2O}2

Reaction of nBu2SnO with thiophene glyoxylic acid yields the title compound which crystallizes as the centrosymmetric distannoxane dimer. Determination of the crystal structure of the compound reveals the presence of two different environments for tin and two distinct carboxylate groups; one of the carboxylate groups bonds to the six-coordinate tin atom via a carboxylate and an α-keto oxygen atom to form a five-membered chelate ring whereas the other carboxylate group forms a unidentate bridge (via one oxygen atom only) across the six-coordinate and five-coordinate tin centres.