An outstanding example of structural diversity and complexity is found in the compounds with the general formula ABi(3)Q(5) (A = alkali metal; Q = chalcogen). gamma-RbBi3S5 (I), alpha-RbBi3Se5 (II), beta-RbBi3Se5 (III), gamma-RbBi3Se5 (IV), CsBi3Se5 (V), RbBi3Se4Te (VI), and RbBi3Se3Te2 (VII) were synthesized from A(2)Q (A = Rb, Cs; Q = S, Se) and Bi(2)Q(3) (Q = S, Se or Te) at temperatures above 650 degreesC using appropriate reaction protocols. gamma-RbBi3S5 and alpha-RbBi3Se5 have three-dimensional tunnel structures while the rest of the compounds have lamellar structures. gamma-RbBi3S5, gamma-RbBi3Se5, and its isostructural analogues RbBi3Se4Te and RbBi3Se3Te2 crystallize in the orthorhombic space group Pnma with a = 11.744(2) Angstrom, b = 4.0519(5) Angstrom , c = 21.081(3) Angstrom, R1 = 2.9%, wR2 = 6.3% for (I), a = 21.956(7) Angstrom, b = 4.136(2) Angstrom, c = 12.357(4) Angstrom, R1 = 6.2%, wR2 = 13.5% for (IV), and a = 22.018(3) Angstrom, b = 4.2217(6) Angstrom, c = 12.614(2) Angstrom, R1 = 6.2%, wR2 = 10.3% for (VI). gamma-RbBi3S5 has a three-dimensional tunnel structure that differs from the Se analogues. alpha-RbBi3Se5 crystallizes in the monoclinic space group C2/m with a = 36.779(4) Angstrom, b = 4.1480(5) Angstrom , c = 25.363(3) Angstrom, beta = 120.403(2)degrees, R1 = 4.9%, wR2 = 9.9%. beta-RbBi3Se5 and isostructural CSBi3Se5 adopt the space group P2(1)/m with a = 13.537(2) Angstrom, b = 4.1431(6) Angstrom, c = 21.545(3) Angstrom, beta = 91.297(3)degrees, R1 = 4.9%, wR2 = 11.0% for (III) and a = 13.603(3) Angstrom, b = 4.1502(8) Angstrom, c = 21.639(4) Angstrom, beta = 91.435(3)degrees, R1 = 6.1%, wR2 = 13.4% for (V). alpha-RbBi3Se5 is also three-dimensional, whereas beta-RbBi3Se5 and CsBi3Se5 have stepped layers with alkali metal ions found disordered in several trigonal prismatic sites between the layers. In gamma-RbBi3Se5 and RbBi3Se4Te, the layers consist of Bi2Te3-type fragments, which are connected in a stepwise manner. In the mixed Se/Te analogue, the Te occupies the chalcogen sites that are on the "surface" of the layers. All compounds are narrow band-gap semiconductors with optical band gaps ranging 0.4-1.0 eV. The thermal stability of all phases was studied, and it was determined that gamma-RbBi3Se5 is more stable than the and alpha- and beta-forms. Electronic band calculations at the density functional theory (DFT) level performed on alpha-, beta-, and gamma-RbBi3Se5 support the presence of indirect band gaps and were used to assess their relative thermodynamic stability.