pH-switchable inversion of the metal-centered chirality of metallabenzenes: opposite stereodynamics in reactions of ruthenabenzene with L- and D-cysteine.

We report herein the first study on the chemical interaction between metallabenzenes and bioactive molecules. Due to its unique stereoelectronic activities, a phenanthroline-derived ruthenabenzene [Ru{CHC(PPh(3))CHC(PPh(3))CH}Cl(C(12)H(8)N(2))(PPh(3))]Cl(2) (1) selectively binds cysteine in aqueous solution at physiological pH and then undergoes a dynamic inversion of configuration at the Ru center. The structure of the L-cysteine-binding product of 1 has been determined by means of X-ray diffraction.

Tris(dibenzoyl-methanido-κO,O')[(6R,8R)-(-)-7,7-dimethyl-3-(2-pyrid-yl)-5,6,7,8-tetra-hydro-6,8-methano-isoquinoline-κN,N']terbium(III).

In the title compound, [Tb(C(15)H(11)O(2))(3)(C(17)H(18)N(2))], the 7,7-dimethyl-3-(2-pyrid-yl)-5,6,7,8-tetra-hydro-6,8-methano-iso-quin-oline (L(RR)) ligand coordinates to Tb(III) through the two N atoms of the heterocycle. The metal centre is also chelated by three deprotonated 1,3-diphenyl-propane-1,3-dione (dbm) ligands, forming enanti-omerically pure [Tb(dbm)(3)L(RR)]. The Tb(III) atom is located in a distorted square anti-prism of eight coordinating atoms (six O and two N atoms).