Ng Seik Weng

Series of anion-directed lanthanide-rigid-flexible frameworks: syntheses, structures, luminescence and magnetic properties

A series of novel self-assembly lanthanide coordination polymers formulated as {[Ce2(pyda)2(μ4-SO4)·5H2O]·2H2O}n (1), {[Gd2(Hpimda)2(μ4-C2O4)·4H2O]·2H2O}n (2), {[Sm4(pyda)2(μ4-C2O4)4·8H2O]·6H2O}n} (3), and {[Gd2(pyda)(μ4-C2O4)2·4H2O]·3H2O}n (4), (H3pimda = 2-propyl-4,5-imidazole-dicarboxylic acid, H2pyda = 2,6-pyridine-dicarboxylic acid) have been synthesized from the reactions of H3pimda or H2pyda with lanthanide salts in the presence of different anions, and were characterized by elemental analysis, IR spectroscopy and X-ray single-crystal diffraction. Compound 1 is a 2D hybrid in which Ce3+ ions are doubly linked by a carboxylate group of the pyda2− ligand. Complexes 2, 3 and 4 have 3D framework structures fabricated through two alternately arranging hexanuclear Ln3+ motifs, among which the guest water molecules are trapped in the 1D tunnel. In 3 and 4, the [Ln2(pyda)2]n layers also consist of alternate left- and right helical chains. Both complexes 2 and 4 exhibit the robust network based on the hexadimeric subunits as 3,3-connected nodes. The emission spectra of the complexes vary depending on which lanthanide ion is present and the aromatic ligands. In addition, compound 1 exhibits weak but significant ferromagnetic couplings between the Ce(III) ions through carboxylato bridges, while dominant antiferromagnetic interactions were observed in compounds 2, 3 and 4.

Preparation and spectroscopic studies of tri(p-tolyl)tin(IV) compounds. X-Ray crystal structure of the quinoline-N-oxide adduct of tri(p-tolyl)tin(IV) bromide

Syntheses and spectroscopic data are presented for R3SnIV compounds, where R is predominantly p-tolyl, of the following types: R3SnX·L (X = Cl, Br or NCS; L = neutral, monodentate oxygen donor), R3SnY (YH = 1,2,4-triazole, N-phenyl-N-benzoylhydroxamic, succinanilic, levulinic and hippuric acids) and [R3SnL2]+ [Ph4B]− (L = neutral, monodentate or 1/2 bidentate oxygen donor). The spectroscopic data (IR and Mossbauer) are interpreted in terms of discrete or weakly polymeric trigonal bipyramidal structures, with the R3Sn skeleton forming the equatorial plane for most of the compounds. A cis-geometry is inferred for the case where the anionic residue is the chelating N-phenyl-N-benzoylhydroxamate ligand, while a meridional geometry is predicted for the cationic complexes involving the chelating ligans, 2,2′-bipyridine N,N′-dioxide and ethylenebis(diphenylphosphine oxide). Both the 13C NMR and the IR data suggest that the Lewis acceptor strength falls in the order (p-ClC6H4)3Sn > (C6H5Sn> (p-MeC6H4)3Sn. Crystals of (p-tolyl)3SnBr· quinoline-N-oxide are triclinic, space group P1, with a 10.245(4), b 10.862(2), c 13.153(5) A, α 84.10(2), β 68.39(3), γ 80.88(3)°. The structure was refined to R = 0.070 for 4548 observed Mo-Kα reflections and comprises independent, non-interacting molecules which are pentacoordinate at tin. The quinoline-N-oxide ligand is coordinated apically to tin in the trigonal-bipyramidal unit; the three tolyl rings occupy the trigonal plane but the tin atom is displaced by 0.17(1) A towards the other apical bromide ligand.

Group IV organometallic compounds. : IX. Preparation and spectroscopic studies of complexes of bis(β-carbomethoxyethyl)tin dichloride

Abstract Bis(β-carbomethoxyethyl)tin dichloride forms coordination complexes of formula R 2 SnCl 2 L 2 , R 2 SnL′ 2 and R 2 SnCl(oxin) where L 2 = 2Ph 3 AsO, phen, bipy and L′ = oxin, . However, it exhibits weaker acceptor properties towards other ligands including phosphine oxides. Structural features of the isolated complexes both in the solid state and in solution are discussed based on spectral (IR, UV, NMR, Mossbauer) evidence.

Square planar platinum(II) complexes. Crystal structures of cis-bis(triphenylphosphine)hydro (triphenylstannyl)platinum(II) and cis-bis(triphenylphosphine)hydro(triphenylsilyl)platinum(II)

Abstract The complexes cis-[PtH(SnPh3)(PPh3)2], cis-[PtH(Sn(C6H4Me-p)3)(PPh3)2], cis-[PtH{Sn(C6H4 Me-p)3}(DIOP)], and cis-[PtH(SiPh3))PPh3)2] have been prepared, and the crystal structures of cis-[PtH(SnPh3) (PPh3)2] and cis-[PtH(SiPh3)(PPh3)2] have been determined. Both of these complexes exhibit distorted square-planar geometry at platinum. In the tin complex, the PtP bonds are almost equal in length, but in the silicon complex, the PtP bond trans to silicon is significantly longer than that cis to silicon, in accord with the larger trans influence of silyl ligands.

Perovskite-structured PbTiO3 thin films grown from a single source precursor.

Perovskite-structured lead titanate thin films have been grown on FTO-coated glass substrates from a single-source heterometallic molecular complex, [PbTi(μ2-O2CCF3)4(THF)3(μ3-O)]2 (1), which was isolated in quantitative yield from the reaction of tetraacetatolead(IV), tetrabutoxytitanium(IV), and trifluoroacetic acid from a tetrahydrofuran solution. Complex 1 has been characterized by physicochemical methods such as melting point, microanalysis, FTIR, (1)H and (19)F NMR, thermal analysis, and single-crystal X-ray diffraction (XRD) analysis. Thin films of lead titanate having spherical particles of various sizes have been grown from 1 by aerosol-assisted chemical vapor deposition at 550 °C. The thin films have been characterized by powder XRD, scanning electron microscopy, and energy-dispersive X-ray analysis. An optical band gap of 3.69 eV has been estimated by UV-visible spectrophotometry.

Group IV organometallic compounds : X. Synthesis and mössbauer studies of some mixed chelate diogranotin(IV) complexes

Abstract Novel mixed chelate complexes of diorganotin(IV) of formula [SnR2L′L′] involving the chelate ligands N,N-dialkyldithiocarbamato (S2CNR′2), 8-quinolinolate (oxin), 2-methyl-8-quinolinolate (quin) and the anion of bisp-fluorobenzoyl)methane (fbm) have been synthesised together with the symmetrical bischelates [SnR2(quin)2] (R  Me, Ph), and the cationic complex, [SnMe2(PPh3O)2(AsPh3O)2][BPh4]2, containing mixed monodentate ligands. Configurational assignments of the SnC bonds in the octahedral structures of these complexes have been made using Mossbauer spectroscopy.

Group 4 organometallic compounds. Part 8. Preparation and Mössbauer spectra of five- and six-co-ordinate di- and tri-organotin compounds containing mixed phenyl and butyl groups on tin

Mossbauer spectroscopic data and preparative details are reported for a range of [SnIVBuPh], [SnIVBu2Ph], and [SnIVBuPh2] compounds. The stereochemical preferences of the butyl and phenyl groups in octahedral and trigonal-bipyramidal co-ordination in these mixed-ligand complexes, relative to their symmetrical analogues, have been examined on the additivity model, with comparison between theory and experiment based on our previously reported data on ligand partial quadrupole splittings. For the derivatives of the two triorganotins, trends in centre shift (c.s.) and quadrupole splitting (q.s.) parameters are reported, which are consistent with the additivity model. An approximate inverse correlation has been noted between q.s. and element–oxygen stretching frequency in comparing complexes of [SnBuxPh3–x](x= 0, 1, or 2) with PPh3O and AsPh3O.

New Dithiocarbamate Compounds from Organotin(IV)

Abstract A series of new organotin(IV) dithiocarbamate compounds of type RnSn (S2CNR′R″)4-n (n = 2, 3; R = dimethyl, dibutyl, diphenyl, triphenyl and tert-butyl; R′ = methyl, ethyl, benzyl; R″ = isopropyl, ethyl, ethanol) have been successfully synthesized. Elemental analysis showed that the percentage of the elements conformed to the general formula of these compounds. The important peaks of the infrared spectra for the stretching mode ν(C˭N), ν(C˭S), and v(Sn-S) for the compounds were observed in the area of 1440–1480 cm−1, 940–1000 cm−1, and 340–90 cm−1, respectively. The 13C NMR spectra showed the most important peak for N13CS2 chemical shifts were observed in the range 190–210 ppm. X-ray single crystal studies for several structures of these compounds showed that the chelating mode of the dithiocarbamate groups to the central tin atoms were either bidentate or anisobidentate. GRAPHICAL ABSTRACT

SYNTHESIS AND SPECTROSCOPIC STUDY OF HETEROLEPTIC MONO-RING SUBSTITUTED TRI-AND TETRA-PHENYLTIN COMPOUNDS CONTAINING THE P-FORMYL OR P-ACETYL SUBSTITU ENT IN ITS FREE, PROTECTED AND DERIVATISED FORMS

Mono-ring substituted tetraphenyltins containing the p-formyl or p-acetyl substituent in its free, protected (ethylene acetal / ketal)) and derivatised (semicarbazone, oxime) forms have been synthesised. Treatment of the carbonyl-protected tetraphenyltin with iodine in DMF, followed by aqueous ΝΗ,ΟΗ yielded P h 2 S n ( C 6 H 4 p C R 0 C H 2 C H 2 0 ) 0 H (R=H,Me). The hydroxide condenses with 3-benzoylpropionic and dimethyldithiocarbamylacetic acids to form the corresponding triaryltin carboxylates. Regeneration of the carbonyl function in the hydroxide was achieved using tartaric acid in aqueous acetone, while treatment of the hydroxide with hydrochloric acid in chloroform/petroleum ether gave in the one step the chloride, Ph2Sn(C6H4-p-C(:0)R)CI. The compounds were characterised by elemental analysis, IR, multinuclear NMR and tin-119m Mössbauer spectroscopy. INTRODUCTION In the course of our studies on the antifungal and insecticidal properties of tin(IV) organyls, we have shown that the strategy of introducing a functionialised esteryl moiety as the anionic residue in triphenyltin(IV) systems as well as that of mono-ring substitution, as exemplified by (4-CIC6H4 )SnPh20C(0)CH2SC(S)NMe2 , can lead to products manifesting increased biological activity and/or selectivity 1-4 compared to the well known crop protectants, triphenyltin acetate and triphenyltin hydroxide .In an extension of this work we sought to prepare other mono-ring substituted derivatives, and in this report we detail the synthesis and spectroscopic properties of compounds containing the para-formylphenyl and para-acetylphenyl groups on tin. EXPERIMENTAL 2-(4-Bromophenyl)-1,3-dioxacyclopentane, b.p.08mm142-44 °C (Lit.b.p.12mm145-147 °C), and 2-(4-bromophenyl)-2-methyl-1,3-dioxacyclopentane, b.p.05mm112-114° C (Lit. b . p . o . 1 3 m b a r 95-98°C) were prepared by condensing 1,2-ethanediol with 4-bromobenzaldehyde and with 4-bromoacetophenone, respectively, in toluene. Synthesis of 4-[2-(1,3-dioxacyclopentyl)phenyl]triphenyltin To the Grignard reagent of 2-(4-bromophenyl)-1,3-dioxacyclopentane prepared in THF under a nitrogen atmosphere from equimolar amounts (0.12 mol) of magnesium and 2-(4bromophenyl)-1,3-dioxalane was added with stirring a solution of triphenyltin chloride (42.5 g,0.11 mol) in THF. The reaction mixture was refluxed for several hours and then hydrolysed at room temperature with a small quantity of aqueous ammonium chloride.The organic phase was separated and this was combined with chloroform extracts of the aqueous phase , and the whole dried over anhydrous calcium chloride and filtered. The filtrate upon concentrating using a rotary evaporator furnished the tetraorganotin compound as a yellow solid in 60% yield based on 2-(4-bromophenyl)-1,3-dioxacyclopentane. H NMR (5,ppm): 4.0-4.2[4H,m, CH2(acetal)],5.8[1 H,s,CH (acetal)],7.4-7.7[19H,m,arom.] Synthesis of 4-formylphenyltriphenyltin A solution of 4-[2-(1,3-dioxacyclopentyl)phenyl]triphenyltin (5 g, 10 mmol) and 4toluenesulfonic acid (200 mg) in 150 mL of a 1:4 (v/v) water/THF mixture was refluxed for several hours, duplicating a literature procedure for the cleavage of the tin-phenyl bond .The reaction mixture was extracted with dichloromethane. The extract was washed with potassium bicarbonate and then concentrated to furnish the crude product. Recrystallisation from chloroform/petroleum ether gave the pure product in 60% yield. H NMR (δ,ρρηη): 7.2-7.9[19H,m,arom.],10.1[1 H,s,CHO]