The synthesis and structures of silver complexes with trimeric thioformaldehyde and trimeric selenoformaldehyde

The compounds [(CH2X)3 2Ag]AsF6 (X = S, Se) have been prepared from (CH2X)3 and AgAsF6 in liquid So2 as minor and major products respectively. Both X-ray crystal structures were determined X = S: P21/c, a 8.579(2), b 20.618(4), c 9.821(2) Å, β 107.95(2)°, R = 0.078 for 2439 reflections. The silver atom shows irregular trigonal coordination, with AgS 2.515, 2.532, 2.764 Å; the extended cation structure is a chain polymer X = Se: C2/c, a 28.80(4), b 9.42(1), c 22.40(4) Å, β 137.4(1)°, R = 0.106 for 1676 reflections. The structure contains isolated [(CH2Se)3 2Ag]+ cations, all six selenium atoms coordinating silver (AgSe 2.78–3.05 Å).