Vimal K. Jain

15N, 13C and 119Sn NMR and other spectroscopic studies of 8-quinolinol, its O- and N-methyl derivatives, and chelate di- and tri-organotin(IV) complexes

Abstract The nature of the 8-quinolinato ligand in various forms has been examined by 15N, 13C and 119Sn NMR spectroscopy, with evidence also from electronic spectroscopy. These forms include 8-quinolinol (HQ), 8-quinolinate, the 8-hydroxyquinolinium ion, O- and N-methyl derivatives, 8-methoxyquinoline (MeQ), the zwitterionic N-methylquinolinium-8-olate and the N-methylquinolinium ion, and the chelating ligand in organotin(IV) complexes. The 15N shift from MeQ to HQ affords a measure of the intramolecular hydrogen bonding in HQ. The 15N shifts and 2J(15N1H) couplings afford criteria of chelation, and the O- and N-methyl compounds provide useful reference points for its assessment. Evidence for chelation is demonstrated in three groups of compounds, [SnR2Q2] (R = Me, Et, Bun, Octn or Ph), [SnR3Q] (R = Me, Et, Bun or Ph) and [SnR2ClQ] (R = Me, Et, Bun or Octn), the 15N and 119Sn shielding increasing from the [SnR3Q] to the [SnR2Q2] compounds.

Tin-119, phosphorus-31, carbon-13 and proton nuclear magnetic resonance and Mössbauer studies of mono-, di- and tri-organotin(IV) dialkyldithiophosphates

Abstract 119 Sn, 31 P, 13 C and 1 H NMR chemical shifts of organotin(IV) dialkyldithiophosphates have been measured in CDCl 3 . The 119 Sn NMR chemical shifts and || 1 J ( 119 SnSn- 13 C)|| and || 2 J ( 119 Sn- 1 H)|| of triorganotin(IV) dialkyldithiophosphates are consistent with tetrahedral, four-coordinated tin, although Mossbauer studies indicate five-coordinated tin in the solid state. The 119 Sn NMR chemical shifts, || 2 J ( 119 Sn- 1 H)|| and Mossbauer parameters of mono- and di-organotin(IV) dialkyldithiophosphates are indicative of weak coordination of the ligands to tin.

Preparation and characterization of mercapto-bridged dinuclear platinum(II) complexes. Catalytic activity of [(PEt3)PtCl(μ-SEt)]2/SnCl2 · 2H2O system in hydrogenation and hydroformylation of styrene

Abstract A series of complexes [(PR 3 )PtX(μ-SR′)] 2 (PR 3 = PEt 3 , PPr 3 n , PBu 3 t or PMe 2 Ph; X=Cl, SnCl 3 , Me, Ph or COPh; R′=Et or Pr i ) and [(P-C)Pt(μ-SR′) 2 (P-C= metalated tri-t-butylphosphine; R′ = Et, Pr n , Pr i Bu n , Bu i ) has been prepared and characterized by elemental analyses, 1 H, 31 P, 13 C and 119 Sn NMR spectroscopy. The stereochemistry of the complexes in solution and the trans influence of the SR′ ligands are discussed. The catalytic activity of the [(PEt 3 )PtCl(μ-SEt)] 2 /SnCl 2 · 2H 2 O system in styrene hydrogenation and hydroformylation has been described.

Organoplatinum(IV) compounds. II: Preparation and characterization of trimethylplatinum(IV) compounds with chelating nitrogen donor ligands. The crystal and molecular structure of iodotrimethyl[bis(3,5-dimethyl-1-pyrazolyl)methane]platinum(IV)

Compounds of the types Me3PtX(NN) (where X = Cl, I, OAc, NO3; NN = bis(1-pyrazolyl)methane (pz2CH2), bis(3,5-dimethyl-1-pyrazolyl)methane ((Me2pz)2CH2), or bis(2-pyridyl)methane (py2CH2)), [Me3Pt(NNN)][PF6] (where NNN=tris(1-pyrazolyl)methane (pz3CH), or tris(2-pyridyl)methane (py3CH)), and [Me3Pt((Me2pz)2CH2(py)][PF6] have been prepared and characterized by elemental analyses and 1H and 13C NMR spectroscopy; the structure of Me6PtI[(Me2pz)2CH2] (1) has also been determined by X-ray crystallography. Crystals of 1 are orthorhombic, space group Pcmn with four molecules in a unit cell of dimensions a 11.936(5), b 14.462(4), c 10.138(5) A. The structure was solved by the heavy-atom method and refined by full-matrix least-squares calculations to R = 0.022 for 1719 observed data. The molecule has crystallographic mirror symmetry. The Pt atom has octahedral geometry with one methyl group trans to iodine and two methyl groups trans to the N atoms of the bidentate ligand (Ptue5f8I 2.843(1), Ptue5f8N, 2.236(4), Ptue5f8C 2.077(6) (trans to I) and 2.032(5) A (trans to N)).

Alkylxanthates of phenylarsenic (III)

Abstract Bis -xanthates of phenylarsenic(III), having the general formula, PhAs(S 2 COR) 2 (where R = Me, Et, Pr n , Pr i , allyl and Bu n ), have been synthesized and characterized by elemental analysis, molecular weight, IR, NMR ( 1 H and 13 C) and mass spectral data which have been discussed in relation to plausible structures for these arsenic derivatives.

Cyclic O,O-alkylenedithiophosphates of phenyl-arsenic and -antimony

Abstract O,O-alkylenedithiophosphate derivatives of the general formula. (where M = As, Sb; G = ue5f8CH2ue5f8C(Me2)ue5f8CH2ue5f8, ue5f8C(Me2)ue5f8C(Me2)ue5f8, ue5f8C(Me2)ue5f8CH2ue5f8CH(Me)ue5f8 and ue5f8CH(Me)ue5f8CH(Me)ue5f8) were synthesized and characterized by elemental analyses and molecular weight determinations. These new complexes are soluble in common organic solvents, and their IR and NMR (1H, 31P) spectral data have been used to investigate a plausible geometry. On the basis of mass spectral data the fragmentation pattern of these derivatives has also been discussed.

The stereochemistry of organotin(IV) oxinates in solution: TIN-119 nuclear magnetic resonance study of triorganotin(IV) oxinates

Abstract Contrary to the previously proposed fluxional trigonal bipyramidal structure for triorganotin(IV) oxinates, the 119 Sn NMR chemical shifts of these compounds are consistent with tetrahedral, 4 coordinate tin. No fluxional processes could be detected in the 1 H and 13 C NMR spectra of Me 3 SnOx down to −90°C.

Syntheses, IR and multinuclear (1H, 13C, 31P, 95Mo) NMR investigation of molybdenum and tungsten carbonyl complexes containing bidentate nitrogen donor ligands

Abstract Complexes of the type [M(CO) 4 (N-N′)] [where M = Mo or W; N-N′ =C 5 H 4 NC(R)=NCH(R′)Ph (R=H or Me; R′ =H or Me); C 9 H(in NCH=NCH(R′)Ph (R′ =H or Me)] and [Mo(CO) 3 (PR 3 ){C 5 H 4 NCH=NCH(Me)Ph}] [where PR 3 =PEt 3 , PPh 3 , P(OEt) 3 , 4-ethyl-2, 6, 7-trioxa-1-phosphabicycle[2.2.2] octane have been synthesized. They were characterized by elemental analyses, IR and NMR ( 1 H, 13 C, 31 P, 95 Mo) spectroscopy. The stereochemistry of these complexes has been discussed on the basis of NMR data. Separate 95 Mo resonances have been observed for the mer form and diastereomers of the fac isomer of [Mo(CO) 3 (PR 3 ){C 5 H 4 NCH=NCH(Me)Ph}] complexes.

Preparation and characterization of some mixed ligand complexes of platinum(II)

Abstract The mixed ligand complexes PtX 2 (ER 3 )L and PtXY(ER 3 )L (where ER 3 = PR 3 or AsMe 3 ; L = phosphine, arsine; X = Cl; Y = Cl, H or Me) have been prepared and characterized. Reaction of PtMe 2 (ER 3 )L with HCl yields PtMeCl(ER 3 )L, in exclusively one of three possible isomeric forms. Excess tetramethyltin reacts with Pt 2 Cl 2 (μ-Cl) 2 (PMe 2 Ph) 2 giving both cis and trans Pt 2 (μ-Cl) 2 (PMe 2 Ph) 2 , as identified from the NMR spectra. Cleavage of Pt 2 (μ-Cl) 2 Me 2 (PMe 2 Ph) 2 with donor ligands such as AsPh 3 , PMe 2 or pyridine, was useful as a synthetic route to the unsymmetrical methylchloro Pt II derivatives. The reaction of cis -[PtMe 2 (PPh 3 )(AsPh 3 )] with excess dimethylacetylenedicarboxylate (DMA) yielded only one product, which was of the formula trans -[Pt{C(COOCH 3 )ue5f8C(COOCH 3 )CH 3 } 2 (PPh 3 )(AsPh 3 )], with the alkenyl groups having the same geometry about the Cue5fbC bond. The use of diethylacetylene-dicarboxylate (DEA) rather than DMA gave a similar product. However, when cis -[PtMe 2 (PEt 3 )(AsPh 3 )] was allowed to react with DMA, two products of the formula trans -[Pt{C(COOCH 3 )ue5fbC(COOCH 3 )CH 3 } 2 (PEt 3 )(AsPh 3 )] were obtained, with the stereochemistry of both alkenyl groups being either cis or trans .

Cleavage of the carbon-silicon bonds in trimethylsilylacetylenes by trans[(PR3)2PtX(R′OH)]PF6 cations and formation of cationic alkoxycarbene complexes of platinum(II)

Abstract Cationic alkoxycarbene complexes of platinum(II) have been isolated in the reactions of trans-[(PR3)2PtX(R′OH)]PF6 (X ue5fb H or Me; R′ ue5fb Me or Et) with Me3SiCue5fcCR′′ (R′′ ue5fb H, Me or SiMe3). In these reactions cleavage of the carbon-silicon bond by the nucleophilic attack of alcohol has been observed. These carbene complexes have been characterized by elemental analyses and by IR, 1H and 13C NMR spectral data. 13C NMR chemical shift data for carbene carbon atoms suggest that the carbene carbon may be very positively charged.