SYNTHESIS AND STEREOCHEMICAL NONRIGIDITY OF ISOMERIC ZN(II) BIS-[N-ISOPROPYLOXY(MERCAPTO)NAPHTHALDIMINATES]

Kinetics and reaction mechanisms governing inversion of the tetrahedra l configuration at the metal center in the series of bis-chelate Zn(II ) complexes of 3,2-, 1,2-, and 2,1-oxy(mercapto)naphthaldimines, respe ctively 4-6, have been studied with the use of dynamic H-1 NMR spectro scopy. A polytopal rearrangement of the diagonal twist type has been f ound to be an energetically preferable pathway of the inversion reacti on for complexes 4 and 5 with a ZnN2O2 coordination site? whereas the inversion reaction for complexes with a ZnN2S2 coordination site occur s by an intramolecular dissociation-recombination pathway that involve s cleavage of a Zn-N coordination bond. In the case of complexes 6, th e inversion reaction is governed mainly by intramolecular degenerate l igand exchange reactions.