21797-13-7, Catalysts are substances that increase the reaction rate of a chemical reaction without being consumed in the process. 21797-13-7, Name is Tetrakis(acetonitrile)palladium(II) tetrafluoroborate, molecular formula is C8H12B2F8N4Pd. In a Article, authors is Moullet, Bertrand£¬once mentioned of 21797-13-7
Kinetic study and crystal structure of tetrakis(1,4-thioxane)palladium(II). A comparison between platinum(II) and palladium(II) reactivity
The compound [Pd(1,4-thioxane)4](BF4)2¡¤4CH 3NO2 crystallizes in the monoclinic space group P21/c with a=9.474(2), b=9.529(5), c=21.945(9) A, beta=99.77(3), Z=2; final R=0.051 for 4325 observed reflections (Pd, C, S and O anisotropically refined). The thioxane ligands around Pd form a square-planar arrangement, with two nitromethane molecules at a distance of 3.115(2) A occupying sites perpendicular to the square-plane formed by the sulfur-bonding thioxanes giving an overall tetragonal bipyramidal coordination around Pd. Intermolecular exchange of 1,4-thioxane on [Pd(1,4-thioxane)4](BF4)2 in deuterated nitromethane and intramolecular interconversion in the bound ligand have been studied as a function of temperature and pressure by 1H NMR lineshape analysis. The first-order rate constant and activation parameters obtained for the intramolecular process, assigned to sulfur inversion, are as follows: ki298=294¡À26 s-1, DeltaHi?=61.9¡À1.9 kJ mol-1, DeltaSi?=+10.2¡À6.5 J K-1 mol-1, DeltaVi?=+2.7¡À0.2 cm3 mol-1. The intermolecular process yielded the following second-order rate constant and activation parameters: k2298=920¡À40 m-1 s-1, DeltaH2?=39.5¡À0.9 kJ mol-1, DeltaS2?=-55.6¡À2.8 J K-1 mol-1, DeltaV2?=-9.5¡À0.3 cm3 mol-1. Second-order kinetics and negative values for the entropy and volume of activation indicate an associative Ia or A exchange mechanism. The reactivity of the analogous Pt2+ compound is estimated using the proposed empirical linear correlation function DeltaG?(Pt)=-32.1+1.92DeltaG?(Pd). The calculated second-order rate constant and free energy of activation are 0.3 m-1 s-1 and 76 kJ mol-1, respectively. This relationship indicates also that the well established reactivity order Pd2+?Pt2+ could be reversed for better pi-accepting ligands than MeNC and that, in this case, five-coordinated species on Pt(II) are more stable than the Pd(II) analogue.
Sometimes chemists are able to propose two or more mechanisms that are consistent with the available data. 21797-13-7, If a proposed mechanism predicts the wrong experimental rate law, however, the mechanism must be incorrect.Welcome to check out more blogs about 21797-13-7, in my other articles.
Reference£º
Chapter 1 An introduction to palladium catalysis,
Palladium/carbon catalyst regeneration and mechanical application method