ИСТИНА

B3LYP structure of Ag(I) fluoroacetate oligomers compared with X-ray data Zulfiya G. Bazhanova, Yury I Tarasov, Dmitry M. Kovtun, Igor V. Kochikov, Alexander I. Boltalin, Boris K. Novosadov Moscow State University, 119991, Moscow, Russia; e-mail: tarasov@phys.chem.msu.ru PC GAMESS program package B3LYP calculations with basis set cc-pVTZ for H, C, O, F atoms and relativistic Stuttgart RCS basis set and effective core potential for atoms Ag(I) give syn- (Fig. 1) and anti- dimeric units with close energies (∆E=13 cm-1) separated by relatively high barrier of the rotation around of the C–C bond (∆E=1092 cm-1). Three dimeric units forming a hexamer are assumed as the fragment of polymeric chains in crystalline structure. According to QC calculations there are possible three optimized structures: (I) – plane structure formed by syn- dimeric units (Fig. 2); (II) – plane structure formed by anti- dimeric units; (III) – the most stable skewed hexamer combined from anti- dimeric units. Relative energies of (I) and (II) are 1382 and 2171 cm-1 respectively. These energy difference are explained by one (in (I)) or two (in (III)) interdimeric Ag(I) … F interaction (calculated bond order is equal to 0.1). For the comparison, Ag(I) – Ag(I) bond order is equal to 0.2, Ag(I) – O bond orders are equal to 0.22 – 0.37. Fig. 1. syn- dimeric unit Fig. 2. hexamer unit (I) According to X-ray experiment 1) Ag(I) fluoroacetate planar chains are formed from syn- dimeric units. The principal experimental and calculated structural parameters are as follows: Ag – O Ag – Ag C – O Ag – Oa) Ag – Aga) Ag – Fa) dimer (calc.) 2.14 2.81 1.25 – 1.26 – – – hexamer (calc) 2.17 – 2.29 2.92 1.24 – 1.27 2.38 – 2.55 3.73 2.90 – 2.94 X-ray 2.16 – 2.23 2.85 1.25 – 1.28 2.48 – 2.49 – – a) – interdimeric distances. Increased Ag(I)-Ag(I) distance in the central dimer unit of hexamer as compared with a free dimer can be explained by influence of neighboring dimer fragments. This work was supported by the RFBR through the grant 08-03-01104-a. 1) E.V. Karpova, A.I. Boltalin et al. Russian J. Coord. Chem., 25 (1), р. 60 (1999).