Dinuclear palladium complex isomerization

Palladium(II) normally coordinates to the N3 atoms of the cytosine base forming a square planar geometry. " An unexpected isomerization from trans- to cA-coordination of ammine ligands about Pd" occurs when tr<2 x-[Pd (NH3)2(H20)2] is added to the mononuclear trans-Pd"(NH3)2(1-methyl cytosine)2(N03)2. The resulting bridged dinuclear Pd" complex has two cis-[Pd (NH3)2] units bridged by cytosines through their to both N3 and deprotonated N4... 

The ophcally active Pd complex with a chiral allenyl ligand undergoes epimer-izahon in the presence of a catalytic amount of Pd(0) complex. This reaction does not involve the isomerization to the propargyl complex, but takes place via a dinuclear intermediate as depicted in Scheme 5.39. The -allenyl ligand in the dinuclear palladium intermediate may racemize via a vinyl-vinyidene intermediate. This type of reaction is prohahly involved in a kinetic resolution of racemic propargyl alcohols promoted hy chiral transihon metal complex [203]. The intermolecular allyl ligand transfer from Pd to Ee complexes occurs under... 

The reactivity of phosphasilenes with organic compounds, for example, [2 + 2]-cycloaddition reaction (8) has been intensively investigated. The reactivity of phosphasilenes with transition metal complexes, however, is comparatively unexplored (9,10). The described phosphasilene 1 can imdergo unprecedented EtZ isomerization of the Si=P bond upon coordination to tungsten (11). Another remarkable reactivity study describes the coordination of group 10 transition metals to phosphasilene 1 generating dinuclear platinum and palladium complexes with Si—P bond cleavage and a bissilylene nickel complex from a Ni(0) precursor (12). 

Dimethyl-1,2,4-triazolium iodide with palladium acetate yields the carbene adduct 182 (97JOM(530)259). Under water it undergoes cis-trans isomerization to 183. Some other derivatives were reported in 1981 (81BCSJ800). 1,1 -Methylenebis(4-alkyl-l,2,4-triazolium)diiodides (alkyl = /-Pr, n-Bu, octyl) with palladium(II) acetate give the mononuclear complexes [L Pdl ] (99EJIC1965), where L2= l,l -methylenebis(4-R-l,2,4-triazol-2-ylidene) (R = /-Pr, n-Bu, octyl). Thermolysis of the products in THF gives the rran -dinuclear complexes 184... 

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