Metal complexes of a biconcave porphyrin with D-4 structure - Versatile chiral shift agents

Representative metal complexes of a biconcave D-4-symmetric porphyrin were synthesised by metal-ion insertion into the porphyrin ligand 1. The NMR spe ctra suggested D-4-symmetry for the Zn-II and dioxo-Ru-VI complexes of 1 an d C-4-symmetry for the unsymmetrically ligated Ru-II and Rh-III complexes. Metal complexes of 1 proved to be versatile chiral H-1 NMR shift agents for a broad spectrum of organic amines, alcohols, carboxylic acids, esters, ni triles and nonpolar fullerene derivatives. A practical analysis of chiral s ubstrates with 1 covers enantiomeric excesses beyond 99 %. An X-ray structu re of (1:1)-cocrystals of an achiral, biconcave Co-II poryphyrinate and C-6 0 provided the first detailed insights into the structure of such a biconca ve metallo-porphyrinate. It also showed remarkable packing of the, carbon s phere against the main concave units of the porphyrin and Save clues about the relevant interactions between biconcave porphyrins and fullerenes.