Synthesis and circular dichroism spectra of silver(I) complexes with R,R-DIOP (4R,5R-trans-4,5-bis[(diphenylphosphino)methyl]-2,2-dimethyl-1,3-dioxalane):: crystal structures of [AgCl(R,R-DIOP]2•2CHCl3, {[AgBr(R,R-DIOP)]2}2•CH2Cl2•2H2O, [AgI(R,R-DIOP)]2 and [AgSCN(R,R-DIOP)]2

The title silver(I) complexes as [AgX(R.R-DIOP)](2) dimers (X = Cl, Br, I or SCN) were synthesized either by the reaction of [Ag(NO3)(R,R-DIOP)](n) with NaX or the reaction of AgX with R,R-DIOP. The complexes were confirmed by elemental analysis, IR, H-1- and P-31-NMR, UV-vis and circular dichroism (CD) spectra, as well as single-crystal X-ray characterization, X-ray analysis showed that the silver atoms are tetrahedral, surrounded by two bridged halides and two phosphorus atoms of the bridged R,R-DIOP ligands. The Ag . . . Ag distances, ranging from 3.065(6) to 3.724(1) Angstrom, are dependent on the polarizability of the halide anions. All of the solid-state structures of the complexes are crystallized in triclinic, space group P1 (no. 1). The CD spectra of these complexes demonstrate their chiratity, and their Cotton effects vary according to the different halides, i.e. a negative band (at 241 nm) for 1 (X = Cl), a positive one for 2 (X = Br) and 3 (X = 1), and a strong positive band for 4 (X = SCN). (C) 2001 Elsevier Science B.V. All rights reserved.