320635-25-4

Upstream product

• 29964-62-3 [1,4-bis(diphenylphosphino)butane] palladium(ll) dichloride 
• 2923-28-6 silver trifluoromethanesulfonate 
• 7688-25-7 1,4-di(diphenylphosphino)-butane 

Relevant academic research and scientific papers

Self-assembly and anion encapsulation properties of cavitand-based coordination cages

Two novel classes of cavitand-based coordination cages 7a-j and 8a-d have been synthesized via self-assembly procedures. The main factors controlling cage self-assembly (CSA) have been identified in (i) a P-M-P angle close to 90° between the chelating ligand and the metal precursor, (ii) Pd and Pt as metal centers, (iii) a weakly coordinated counterion, and (iv) preorganization of the tetradentate cavitand ligand. Calorimetric measurements and dynamic 1H and 19F NMR experiments indicated that CSA is entropy driven. The temperature range of the equilibrium cage-oligomers is determined by the level of preorganization of the cavitand component. The crystal structure of cage 7d revealed the presence of a single triflate anion encapsulated. Guest competition experiments revealed that the encapsulation preference of cages 7b,d follows the order BF4- > CF3SO3- ? PF6- at 300 K. ES-MS experiments coupled to molecular modeling provided a rationale for the observed encapsulation selectivities. The basic selectivity pattern, which follows the solvation enthalpy of the guests, is altered by size and shape of the cavity, allowing the entrance of an ancillary solvent molecule only in the case of BF4-.

Cationic complexes of palladium(II) and platinum(II) as Lewis acid catalysts for the Diels-Alder reaction

The synthesis of a series of Pd(II) and Pt(II) cationic complexes of the types [(P-P)M(solv)](Y)2, [(P-P)M(η2-Y)](Y), and [(P-P)M(μ-Cl)]2(Y)2 (where P-P = various diphosphines including chiral diphosphines (M = Pd, Pt; Y = TfO-, ClO4-, BF4-) is reported. All complexes are excellent catalysts for the Diels-Alder reaction between cyclopentadiene or cyclohexadiene and a number of simple dienophiles such as acrolein, methacrolein, and methylvinyl ketone. Some of the complexes modified with chiral diphosphines can act as enantioselective catalysts in the Diels-Alder reaction under mild condition with moderate ee's. A critical point in this respect is the presence of only one vacant coordination site in the catalyst.

Influence of ligands and anions on the insertion of alkenes into palladium-acyl and palladium-carbomethoxy bonds in the neutral complex (dppp)Pd(C(O)CH3)Cl and the ionic complexes +SO3CF3- (P-P = dppe, dppp, dppb; R = C(O)CH3, L= CH3CN, PPh3; R = C(O)OCH3, L = PPh3)

Insertions of alkenes in Pd-acetyl bonds of (dppp)Pd(C(O)CH3)Cl and +SO3CF3- (P-P = dppe, dppp, dppb; L = CH3CN, PPh3) have been studied as a function of the ligand, the anion and the alkene.The neutral acetyl complex (dppp)Pd(C(O)CH3)Cl underwent insertion only with norbornadiene and norbornene, while the ionic acetyl complexes +SO3CF3- (P-P = dppe, dppp, dppb) reacted with norbornadiene, norbornene, styrene, cis-stilbene, 1-pentene, 3,3-dimethyl-1-butene, vinyltrimethylsilane, methyl vinyl ketone, methyl acrylate, diethyl fumarate, and diethyl maleate.This insertion was observed to give an intermediate in which there was intramolecular coordination of the ketone oxygen atom to the palladium centre.In monosubstituted alkenes the acetyl group migrates to the unsubstituted carbon atom.The insertion products underwent β-elimination to give (trans) unsaturated ketones and a palladium hydride.The rate of this elimination was higher for complexes containing ligands L-L with smaller bite angles (dppe > dppp), and the rate of insertion showed the reverse order.The carbomethoxy complexes +SO3CF3- (P-P = dppe, dppp, dppb) were prepared from (P-P)Pd(SO3CF3)2 with CO, CH3OH and PPh3.The carbomethoxy complex reacted with norbornadiene to give a carbomethoxy oxygen-coordinated intermediate.The carbomethoxy complexes were less reactive than the analogous acetyl complexes towards alkenes.