Synthesis and structural characterization of rare earth metal disulfonamide complexes

The reaction of rare earth silylamides Ln[N(SiHMe2)(2)](3)(thf)(n) [n = 1 for Sc (1a); n = 2 for Y (1b), La (1c), Nd (1d)] with trans-1,2-bis(2,4,6-triisopropylbenzenesulfonamido)cyclohexane (H2L, rac-2) in toluene at ambient temperature proceeds via an extended silylamide route, affording highly soluble complexes Sc(L)[N(SiHMe2)(2)] (3) and Ln(L)[N(SiHMe2)(2)] (thf) (4a-c) in excellent yields. An X-ray crystallographic study performed on the solvent-free, dinuclear yttrium derivative 5 revealed an unusual mu(2),eta(4):eta(1)-coordination of the disulfonamide Ligand, involving bridging S=O groups. In solution, equilibria between dimeric and monomeric forms, dependent on the presence of a donor molecule, were observed by NMR techniques.