Isolation of beta-Ag3AsSe3, (Me(3)NH)[Ag3As2Se5], K5Ag2As3Se9, and KAg3As2S5: Novel solid state silver thio- and selenoarsenates from solvento-thermal synthesis

Three new solid state silver selenoarsenates and one thioarsenate prepared from hydro- and methanothermal synthesis are described. beta-Ag3AsSe3 (I) and (Me(3)NH)[Ag3As2Se5] (II) were synthesized hydrothermally at 110 degrees C from a mixture of AgBF4/3K(3)AsSe(3) and AgBF4/3K(3)AsSe(3)/6Me(3)NHCl, while K-5[Ag2As3Se9] (III) and K[Ag3As2S5] (IV) were synthesized methanothermally at 110 degrees C from a mixture of AgBF4/3K(3)AsS(3) and AgBF4/3K(3)AsSe(3), respectively. beta-Ag3AsSe3(I) crystallizes in the orthorhombic space group Pnma (No. 62) with a = 8.111(1) Angstrom, b = 11.344(2) Angstrom, c = 20.728(3) Angstrom Z = 8, V = 1907(1) Angstrom(3). This compound is a new allotrope of alpha-Ag3AsSe3 and has a complex three-dimensional structure composed of distorted trigonal planar and tetrahedral Ag+ ions and [AsSe3](3-) units. (Me(3)NH)[Ag3As2Se5] (II) crystallizes in the triclinic space group P - 1 (No. 2) with a = 10.119(2) Angstrom, b = 18.010(4) Angstrom, c = 14.932(3) Angstrom, alpha = 110.20 (1)degrees, beta = 103.98(2)degrees, gamma = 99 99(1)degrees, Z = 2, V = 729.3(8) Angstrom(3). The [Ag3As2Se5](n-)(n) anion in (II) has a complex two-dimensional layered structure with tetrahedral Ag+ ions and [As2Se5](4-) units. K-5[Ag2As3Se9] (III) crystallizes in the orthorhombic space group Pnma (No. 62) with a = 12.599(2) Angstrom, b = 12.607(4) Angstrom, c 14.067(3) Angstrom, Z = 8, V = 2234(1) Angstrom(3). The [Ag2As3Se9](5n-)(n) anion in (III) has a two-dimensional layered structure with tetrahedral Ag+ ions and two different kinds of selenoarsenate units, [AsSe4](3-) and [As2Se5](4-). K[Ag3As2S5] (IV) also crystallizes in the orthorhombic space group Pnma (No. 62) with a 19.210(2) Angstrom, b = 16.867(2) Angstrom, c = 6.3491(7) Angstrom, Z = 8, V = 2057.2(7) Angstrom(3). The [Ag3As2S5](n-)(n) anion in (IV) possesses a complicated two-dimensional structure with tetrahedral Ag+ ions and two kinds of thioarsenate ligands, [AsS3](3-) and [As3S7](5-). The thermal stability and optical absorption properties of these compounds are reported. (C) 1996 Academic Press.