PubMed Health⌕ Search

Biomedical subjects

Jagadese J. Vittal

Publications and source records attributed to Jagadese J. Vittal.

7 recordsLinked to original sources
PubMed1999

Synthesis of Metallacycles by Oxidative Addition of Sn-S, Sn-Se, Sn-Te, and Ge-Te Containing Precursors to Platinum(II).

The first metallacycles formed by oxidative addition of tin-sulfur, tin-selenium, tin-tellurium, and germanium-tellurium bonds to platinum(II) are reported. In particular, the ring compounds [(R(2)SnE)(3)], where R = Me, Ph and E = Se, Te, and the new compound [(Me(2)GeTe)(3)], react with [PtMe(2)(bu(2)bpy)] (bu(2)bpy = 4,4'-di-tert-butyl-2,2'-bipyridine) to give the new organoplatinum(IV) metallacycles [PtMe(2)(R(2)SnE)(2)(bu(2)bpy)] and [PtMe(2)(Me(2)GeTe)(2)(bu(2)bpy)], respectively. The tin-containing metallacycles complexes can undergo exchange of either the R(2)Sn or the E groups by reaction with [(R'(2)SnE)(3)] or [(R(2)SnE')(3)], respectively, to give the corresponding new metallacycles of general formula [PtMe(2)(R(2)SnE-R'(2)SnE)(bu(2)bpy)] or [PtMe(2)(R(2)SnE-R(2)SnE')(bu(2)bpy)]. The isostructural series of complexes [PtMe(2)(Ph(2)SnE)(2)(bu(2)bpy)] with E = S, Se, and Te have been characterized by X-ray structure determinations. It is shown that (119)Sn NMR is a useful method of structure determination for these metallacyclic compounds.

Journal Article↗
PubMed1998

Heteronuclear Hexaplatinum Cluster Complexes: Structure as a Function of Electron Count.

The 84-electron hexaplatinum cluster complex [Pt(6)(&mgr;-CO)(6)(&mgr;-dppm)(3)], 1, dppm = Ph(2)PCH(2)PPh(2), reacts in a 1:2 molar ratio with either 0-electron metalloligands LM(+) (L = Ph(3)P, M = Cu, Ag, Au; L = iPr(3)P, M = Au) or InX(3) (X = Cl, Br) or 2-electron metalloligands Tl(+) and Hg to give the corresponding 84-electron clusters [Pt(6)(&mgr;(3)-ML)(2)(&mgr;-CO)(6)(&mgr;-dppm)(3)](2+) or [Pt(6)(&mgr;(3)-InX(3))(2)(&mgr;-CO)(6)(&mgr;-dppm)(3)] or 88-electron clusters [Pt(6)(&mgr;(3)-Tl)(2)(&mgr;-CO)(6)(&mgr;-dppm)(3)](2+) and [Pt(6)(&mgr;(3)-Hg)(2)(&mgr;-CO)(6)(&mgr;-dppm)(3)], respectively. The mercury cluster is oxidized by CH(2)I(2) to give the known 86-electron cluster [Pt(6)(&mgr;(3)-HgI)(2)(&mgr;-CO)(6)(&mgr;-dppm)(3)]. Reaction of 1 with [Ir(CO)(4)](-) occurs in a 1:1 ratio only to give the 98-electron anionic cluster [Pt(6){&mgr;(3)-Ir(CO)(2)}(&mgr;-CO)(6)(&mgr;-dppm)(3)](-), which reacts with [Ph(3)PAu](+) to give [Pt(6){&mgr;(3)-Ir(CO)(2)}(&mgr;(3)-AuPPh(3))(&mgr;-CO)(6)(&mgr;-dppm)(3)]. The new cluster complexes are characterized by NMR and IR spectroscopies, and [Pt(6)(&mgr;(3)-AuPiPr(3))(2)(&mgr;-CO)(6)(&mgr;-dppm)(3)](2+) is also characterizedby an X-ray structure determination.

Journal Article↗
PubMed1998

Dicopper(II) Complexes of the Antitumor Analogues Acylbis(salicylaldehyde hydrazones) and Crystal Structures of Monomeric [Cu(2)(1,3-propanedioyl bis(salicylaldehyde hydrazone))(H(2)O)(2)].(ClO(4))(2).3H(2)O and Polymeric [{Cu(2)(1,6-hexanedioyl bis(salicylaldehyde hydrazone))(C(2)H(5)OH)(2)}(m)()].(ClO(4))(2)(m)().m(C(2)H(5)OH).

Salicylaldehyde hydrazones derived from acyldicarboxylic acids (H(4)L(n)(), where n = 0, 1, 2, 4, 6, 8, 10, 14 and is the number of methylene units) of varying chain length have been prepared, and their dicopper(II) complexes have been isolated as bis analogues of antitumor carboxylate hydrazones. The predominant structural form adopted is polymeric, with [{Cu(2)L(n)()}(m)()] formed in neutral or basic solution, [{Cu(2)(H(2)L(n)())Cl(2)}(m)()] from dilute HCl, and [{Cu(2)(H(2)L(n)())}(m)()].(ClO(4))(2)(m)() from dilute HClO(4). The crystal structures of [Cu(2)(H(2)L(1))(H(2)O)(2)].(ClO(4))(2).3H(2)O and [{Cu(2)(H(2)L(4))(C(2)H(5)OH)(2)}(m)()].(ClO(4))(2)(m)().m(C(2)H(5)OH) have been determined. The structure of [Cu(2)(H(2)L(1))(H(2)O)(2)]. (ClO(4))(2).3H(2)O consists of discrete di-Cu(II) molecules with nonsymmetry-related Cu(II) centers. The copper atoms are square-planar with H(2)L(1) supplying two tridentate, monoanionic ONO domains and water completing the coordination sphere. The two metal-binding domains are inclined at 80 degrees to each other. For [{Cu(2)(H(2)L(4))(C(2)H(5)OH)(2)}(m)()].(ClO(4))(2)(m)().m(C(2)H(5)OH) the symmetry-related copper atoms are square-pyramidal with the base composed of H(2)L(4), acting as a tridentate ONO chelator, and an O-bonded ethanol molecule. Axial phenolato bridges complete the coordination sphere, linking molecules to give a polymer. Compounds prepared have been characterized by a range of physicochemical and spectroscopic techniques, and proton and metal ion stability constant data have been determined.

Journal Article↗
PubMed1996

Chemistry of Thiobenzoates: Syntheses, Structures, and NMR Spectra of Salts of [M(SOCPh)(3)](-) (M = Zn, Cd, Hg).

The salts (Ph(4)E)[M(SOCPh)(3)] (M = Zn, Cd, or Hg; E = P or As) are produced by the reaction of Zn(NO(3))(2).6 H(2)O, Cd(NO(3))(2).4H(2)O or HgCl(2) with Et(3)NH(+)PhCOS(-) and (Ph(4)E)X (E = P, X = Br; E = As, X = Cl) in aqueous MeOH in the ratios M(II):PhCOS(-):Ph(4)E(+) = 1:>/=3:>/=1. The crystal structures of (Ph(4)P)[Zn(SOCPh)(3)] (1), (Ph(4)As)[Cd(SOCPh)(3)] (2) and (Ph(4)P)[Hg(SOCPh)(3)] (3) have been determined by single-crystal X-ray diffraction experiments. Crystal data for 1: triclinic; space group P&onemacr;; Z = 2; a = 10.819(2) Å, b = 13.219(3) Å, c = 15.951(3) Å; alpha = 101.75(2) degrees, beta = 97.92(1) degrees, gamma = 109.18(2) degrees. Crystal data for 2: triclinic; space group P&onemacr;; Z= 2; a = 10.741(2) Å, b = 13.168(2) Å, c = 15.809(2) Å; alpha = 101.00(1) degrees, beta = 97.65(1) degrees, gamma = 109.88(1) degrees. Crystal data for 3: monoclinic; space group P2(1)/n; Z = 4; a = 13.302(2) Å, b = 14.276(2) Å, c = 21.108(2) Å; beta = 90.92(1) degrees. The compounds 1 and 2 are isomorphous and isostructural. In the anions [M(SOCPh)(3)](-) the metal atoms have trigonal planar coordination by three sulfur atoms. The metal atoms are further more weakly coordinated intramolecularly to one (M = Hg) or two (M = Zn, Cd) thiobenzoate oxygen atom(s). Using the Bond Valence approach it is found that the contribution of M.O bonding to the total bonding is in the order Cd > Zn > Hg. The metal ((113)Cd, (199)Hg) NMR signals of [M(SOCPh)(3)](-) (M = Cd, Hg) are more shielded than those found for MS(3) kernels in thiolate complexes, a difference attributed to the M(.)O bonding in the thiobenzoate complexes. The (113)Cd resonance of [Cd(SOCPh)(3)](-) in dilute solution is in the region anticipated from dilution data for [Na(Cd{SOCPh}(3))(2)](-).

Journal Article↗