Synthesis, NMR characterisation and crystal structure of the silver(I) annular complex [Ag-2(mu-ppye)(2)][PF6](2)center dot 2(CH3)(2)CO (ppye=1-(diphenylphosphino)-2-(2-pyridyl)ethane)

The silver(I) complex [Ag-2(mu-ppye)(2)][PF6](2) . 2(CH3)(2)CO (ppye = 1-(diphenylphosphino)-2-(2-pyridyl)ethane) has been prepared and its crystal structure determined by single-crystal X-ray diffraction. The dication [Ag-2(mu-ppye)(2)](2+) exhibits a twelve-membered annular core structure with ppye ligands bridging head-to-tail the silver ions, which lie in a distorted linear environment. Each Ag(I) centre shows also a weak electrostatic interaction with the oxygen atom of an acetone molecule (Ag ... O = 2.86(1) Angstrom), which is probably responsible for the deviation from linearity of the P-Ag-N angle (165.8(1)degrees). The size of the cavity can be estimated on the basis of the Ag ... Ag distance, 5.077(1) Angstrom. Crystallographic data: monoclinic, space group P2(1)/n, a = 13.330(1), b = 13.469(1), c = 14.102(2) Angstrom, beta = 103.02(5)degrees, U = 2466.7(6) Angstrom(3), Z = 2, R = 0.071. The dynamic behaviour of the complex in acetone solution has been investigated by means of variable temperature multinuclear (H-1, C-13 and P-31) NMR spectroscopy.