149 research outputs found
U. Belluco, P. Rigo, M. Graziani, R. Ettorre: Solvent effect on the leaving group in displacements on trans [Pt (P(C2 H5)3)2)XR]
No full textInfrared studies and equilibriums of new platinum(II) hydrido-complexes
No full textThe prepn. of new hydrido cationic species of the general formula [Pt(PEt3)2LH]X is reported (L = AsPh3, SbPh3, thiourea, sopropylamine, 3-chloropyridine, 3-methylpyridine, 2,6-dimethylpyridine, and 4-cyanopyridine), together with the reaction of trans-[Pt(PEt3)2(H)Cl] with 1,2-diarsinoethane.
Equil. indexes for the reactions trans-[Pt[PEt3)2HCl] + L .rdblhar. trans-[Pt(PEt3)2LH]+ + Cl- in EtOH (L = PPh3, AsPh3, SbPh3, pyridine, 4-cyanopyridine, isopropylamine, and thiourea) have also been measured. The greater the equil. index of the cationic hydrido species the lower is the stretching frequency of the Pt-H bond
Polynuclear complexes of palladium(II) with halogen and sulfur bridges
No full textThe reaction of Na2[PdCl4] with Ph2S2 in MeOH yields a polymeric compd. of formula [Pd(SPh)Cl]n (I) contg. alternating
halogen and S bridges. This compd. is also formed by refluxing [Pd(Ph2S2)-Cl2]2 in MeOH. The characterization of I was based on its ir spectra and on its bridge-splitting reactions. In the reaction of I with a neutral ligand L (L = pyridine, Ph3P, Ph3As) S-bridged complexes of the type [Pd(SPh)LCl]2 are formed. The reaction with ethylenediamine yields the cationic S-bridged complex [Pd(SPh)(en)]2Cl2, whereas with [AsPh4]Cl the anionic complex [Pd(SPh)Cl2]2[AsPh4]2 is formed. The above reactions involve only splitting of the Cl-Pd bridges. When I reacts either with 1,2- bis(diphenylphosphino)ethane or with an excess of phosphine, both the halogen and S bridges are cleaved. The nature of the products in the bridge-splitting reactions has been detd. on the basis of elemental anal., ir spectra, cond., and mol.
wt. measurements, where possible
Synthesis and spectroscopic characterization of cis and trans isomers of bis(nitrile)dicloroplatinum(II) complexes
No full textFluxional behavior of allylpalladium(II) derivatives of N,N'-diarylformamidines and 1,3-diaryltriazenes
No full textReactions of allylpalladium chloride dimer with neutral ligands (L = RN:CHNHR, R = PhCH2, p-MeC6H4, p-ClC6H4; L =
RN:NHR, R = p-MeC6H4, p-ClC6H4) afford bridge splitting products PdClL(1,3--C3H5). Variable temp. 1H and 13C
NMR spectra show 2 dynamic processes in soln. The first one, operating at room temp., involves the dissocn. of the
neutral ligand L; the second one, which has a lower activation energy, is concn. dependent and involves chloride-L
exchange, probably via a pentacoordinated chloro bridge species. The influence of the basicity of the ligands on the
activation energies of the processes is discussed
Evidence for platinum(II)-vinylidene complexes and their reactions with water to give hydrocarbons and olefins
No full textTreatment of the alkynyl complexes trans-[Pt(Me)(CCR)(PPh3)2] (R=p-tolyl (1a), Ph (1b)) at low temperature in a CD2Cl2 solution with stoichiometric amounts of the acids HBF4·Et2O or CF3SO3H affords the corresponding vinylidene derivatives trans-[Pt(Me){=C=C(H)R}(PPh3)2]X (R=p-tolyl, X=BF4 (2aBF4); R=p-tolyl, X=CF3SO3 (2aCF3SO3); R=Ph, X=BF4 (2bBF4)) on the basis of 1H- and 31P{1H}-NMR data. The reactions of the in situ generated complexes 2 with water, which were followed by 1H- and 31P{1H}-NMR, lead to the formation of a mixture of the carbonyl complex [Pt(Me)(CO)(PPh3)2]X (3) and the hydroxo-bridged dinuclear compound [Pt(μ-OH)(PPh3)2]2X2 (4) in a ca. 1:2 ratio. The formation of 3 and 4 is accompanied with the liberation of hydrocarbons R-CH3 and olefins CH3CH=CHR (R=p-tolyl, Ph), respectively, which arise from the vinylidene ligand likely via an hydroxycarbene intermediate
Pulmonary impairments in silicon carbide workers
No full textAbstract: Two hundred and sixty seven workers employed in the manufacture of silicon carbide (SiC) were examined to determine the effects of exposure to contaminants (SiC, quartz, and SO2) in the workplace on pulmonary function. No exposure concentrations exceeded the current permissible limits. Ten subjects (3.7%) showed rounded opacities (profusion greater-than-or-equal-to 1/0). Two subjects employed only in the final stages of the production process and not exposed to crystalline silica showed opacities (profusion q1/0 and q2/1) on x ray film suggesting a role of SiC in the genesis of interstitial lung disease. Chest abnormalities on x ray film were correlated with cumulative exposure to dust and pulmonary function was affected by cumulative dust exposure, profusion of opacities, and smoking. It is concluded that the current standards do not provide adequate protection against pneumoconiosis and chronic pulmonary disease in this industry
- …
