Homo- and heterometallic chiral dynamic architectures from allyl-palladium(II) building blocks.

New chiral tetranuclear square-like homo- and heterometallamacrocycles containing allyl-palladium and either {Pd(P-P)*} or {Pt(P-P)*} optically pure moieties (P-P* = (2S,3S)- O -isopropylidene-2,3-dihydroxy-1,4-bis(diphenylphosphanyl)butane (( S , S )-DIOP) and (2 S ,4 S )-2,4-bis(diphenylphosphanyl)pentane (( S , S )-BDPP)) have been obtained by the self-assembly of [Pd(η 3 -2-Me-C 3 H 4 )(4-PPh 2 py) 2 ] + and [M(P-P)*(H 2 O) 2 ] 2+ building blocks in a 1 : 1 molar ratio. The supramolecular assemblies thus prepared [{Pd(η 3 -2-Me-C 3 H 4 )} 2 (4-PPh 2 py) 4 {M(P-P)*} 2 ](CF 3 SO 3 ) 6 (M = Pd, Pt) have been fully characterised by multinuclear NMR spectroscopy and MS spectrometry. The structures display remarkable differences on their dynamic behaviour in solution that depend on the lability and thermodynamic strength of M-py bonds. The structural characteristics of the new metallamacrocyles obtained have also been unambiguously established by XRD analysis. The architectures have been assayed as catalytic precursors in the asymmetric allylic alkylation reaction.