Palladium II cyanide

Palladium (II) cyanide [2035-66-7] M158.1. A yellow solid, wash well with H2O and dry in air. [Inorg Chem 2 245 1946]. 

Mercury(II) cyanide solution white precipitate of palladium(II) cyanide, Pd(CN)2 (difference from platinum), sparingly soluble in dilute hydrochloric acid, readily soluble in potassium cyanide solution and in ammonia solution. 

Rammelsberg and Rossler state that potassium tetra-cyanopalladate(II) can be prepared by first precipitating palladium(II) cyanide and then dissolving it in additional potassium cyanide. The method given here differs from theirs only in that care is taken to wash the precipitated palladium (II) cyanide free from potassium chloride, which otherwise would have to be separated by fractional crystallization. 

Five grams of palladium(II) chloride [or 8 g. of ammonium tetrachloropalladate(II)] is dissolved in about 350 ml. of warm water to which a few drops of hydrochloric acid has been added. To the well-stirred solution is added dropwise a solution of 3.7 g. of potassium cyanide in about 50 ml. of water. As yellow palladium(II) cyanide precipitates, the supernatant liquid becomes colorless. The gelatinous precipitate is filtered on a Buchner funnel, washed well with water, transferred to a beaker, and dissolved in a solution of 4 g. of potassimn cyanide in about 75 ml. of water. Heat and agitation aid the solution process. The liquid is filtered and evaporated on a hot plate imtil crystals begin to form. When the solution has cooled, the crystals are filtered on a small Bttchner funnel and washed with a few drops of cold water. The process of evaporation, cooling, and filtering off the crystals formed may be repeated once or twice with the mother liquor. The salt may be purified by recrystallization from water ... 

Trimethylsiloxyphenyl isocyanide enters the cyclization reaction with [MCl2(NCPh)2] (M = Pt, Pd) to yield the homoleptic tetracarbenes 77 (M=Pt, Pd) (97JOM(541)51). Complex 77 (M = Pd) enters an interesting reaction with ammonia to yield the species 78 where two of this benzoxazol-2-ylidene ligands are deprotonated and become C-coordinated benzoxazole moieties, while the other two remain intact. Palladium(II) iodide in these conditions behaves differently yielding the di-Mo-cyanide complex, which in the presence of tetra- -butyl ammonium fluoride gives the dicarbene 79. 

Determination of silver as chloride Discussion. The theory of the process is given under Chloride (Section 11.57). Lead, copper(I), palladium)II), mercury)I), and thallium)I) ions interfere, as do cyanides and thiosulphates. If a mercury(I) [or copper(I) or thallium(I)] salt is present, it must be oxidised with concentrated nitric acid before the precipitation of silver this process also destroys cyanides and thiosulphates. If lead is present, the solution must be diluted so that it contains not more than 0.25 g of the substance in 200 mL, and the hydrochloric acid must be added very slowly. Compounds of bismuth and antimony that hydrolyse in the dilute acid medium used for the complete precipitation of silver must be absent. For possible errors in the weight of silver chloride due to the action of light, see Section 11.57. 

In the presence of aqueous acetic acid the 4//-azepi ne 9 yields the hydroxy derivative 10 a. Addition of methanol, in the presence of Sephadex LH20, and cyanide ion in the presence of palladium(II) acetate, are also successful and yield 4,5-dihydro-l //-azepines 10b and 10c, respectively.113... 

An approach to isobacteriochlorins1 ln-e makes use of Pd(II) or metal-free bilatrienes 1 as starting materials. Cyclization of the corresponding bilatriene derivatives is induced by base in the presence of palladium(II) or zinc(II) which exercise a template effect. Zinc can be readily removed from the cyclized macrotetracycles by acid whereas palladium forms very stable complexes which cannot be demetalated. Prior to the cyclization reaction, an enamine is formed by elimination of hydrogen cyanide from the 1-position. The nucleophilic enamine then attacks the electrophilic 19-position with loss of the leaving group present at the terminal pyrrole ring. 

In a related study, Srivastava and Collibee employed polymer-supported triphenyl-phosphine in palladium-catalyzed cyanations [142]. Commercially available resin-bound triphenylphosphine was admixed with palladium(II) acetate in N,N-dimethyl-formamide in order to generate the heterogeneous catalytic system. The mixture was stirred for 2 h under nitrogen atmosphere in a sealed microwave reaction vessel, to achieve complete formation of the active palladium-phosphine complex. The septum was then removed and equimolar amounts of zinc(II) cyanide and the requisite aryl halide were added. After purging with nitrogen and resealing, the vessel was transferred to the microwave reactor and irradiated at 140 °C for 30-50 min... 

Aside from alkoxycarbonylations, hydroxycarbonylations in the presence of water to yield allenic carboxylic acids [15] (93, Y = OH) and aminocarbonylations in the presence of amines to give the analogous amides [139] (93, Y = NRR ) have also been carried out, respectively (Scheme 7.13). These products of structure 102 can also be obtained if using the propargylamines 101 with R1 = Ph or R3 Z H as starting materials (Scheme 7.15) [140]. Additionally, hydroxycarbonylations, also termed carboxyla-tions, are successful without palladium catalysis by reaction of propargyl halides and carbon monoxide in the presence of nickel(II) cyanide under phase-transfer conditions [141, 142]. 

Nickel(O) or palladium(II) compounds in stoichiometric amounts promote the ring enlargement of simple alkyl-substituted 1,2-divinylcyclobutanes in benzene at room temperature to give 1 1 metal complexes of cycloocta-1,5-dienes.119 Destruction of the palladium complexes with potassium cyanide affords the free cycloocta-1,5-dienes. The stereochemistry observed is the same as in the thermal reaction at 150°C. 

Palladium (II) acetate Cerium (III) chloride Thionyl chloride Sodium cyanide Triethylamine Potassium t-butoxide... 

Carbonylation of benzyl chloride This reaction can be effected with cobalt carbonyl or a palladium(O) catalyst under phase-transfer conditions. CeCl3 promotes this phase-transfer process and also permits the use of nickel(II) cyanide as the... 

The incorporation of the cyclopropyl group into complex molecules is often complicated or laborious. However, allyl cyanide was cyclopropanated in 88% yield by using a sixfold molar excess of diazomethane in the presence of palladium(II) acetate as the catalyst. The cyclo-... 

Diazo compound 2 is obtained by thermal ring opening of the bicyclic pyrazoline 1." Catalytic decomposition of 2 with copper(I) iodide in refluxing benzene yields the bicyclo[1.1.0]butane 3. The same result is achieved with bis(acetonitrile)palladium(II) chloride as catalyst, whereas rhodium(II) acetate dimer and copper(I) cyanide are unreactive. 

Palladium (Pd, at. mass 106.42) is a platinum-group metal, and occurs in the II and IV oxidation states. Palladium(II) compounds are the more stable. Unlike the other platinum metals, palladium is soluble in cone. HNO3. Brown-red Pd(OH)2 precipitates at pH 4, but dissolves in excess of an alkali-metal hydroxide. Palladium(ll) gives stable nitrite, ammine, cyanide, chloride, bromide, and iodide complexes. Palladium(ll)- and (IV) are reduced to the metal by SO2, Fe(II), and ethanol. 

Palladium-catalyzed coaddition of vinyl or aryl halides and cyanides is achieved stereose-lectively (cis-exo) when potassium or sodium cyanide in the presence of palladium(II) acetate and triphenylphosphane in tetrahydrofuran or dimethylformamide is used3173. Palladium-catalyzed addition with copper cyanide, which gives excellent yields in a stoichiometric version15, leads to only small yields of the adduct31, while addition of tributyltin cyanide fails7. 

Enones can be reduced to the saturated ketones with triethylsilane and Wilkinson s catalysis62 (equation 54). Interestingly, the same product was prepared via a Tiffeneau-Demjanov ring expansion wherein trimethylsilyl cyanide was used (equation 55). The selective reduction of the double bond of enones can also be carried out with diphenylsilane in the presence of palladium(O) or palladium(II) and zinc chloride63 (equation 56), or more effectively with phenylsilane and molybdenum hexacarbonyl64 (equation 57). This latter reagent was also used to reduce the double bond of a,/ -unsaturated esters, amides and nitriles. 

AMIDES Boron tribromide. Boron trifluoride etherate. 6-Chloro-l-p-chlorobenzene-sulfonyloxybenzotriazole. Diethylphosphoryl cyanide. Dihalobis(triphenylphosphine)-palladium(II). Dihalobis(triphenylphosphine)palladium(II) complexes. Palla-dium(ll) chloride. Sodium amide. Trimethylsilyl isocyanate. Triphenylphosphine ditriflate. 

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