The molecular and crystal structures of the products of the reaction between the building block [Cr(phen)(2)(C2O4)(2))](-) and several monovalent ions, two from the alkaline group (Na+, K+) and 4-NH(3)pyridine(+), N-(n-butyl)(4)(+), and PPh4+ were studied by crystallographic methods. Na(Cr(phen)(2)(C2O4)(2)). 3H(2)O (1) is monoclinic, P2(1)/c, a = 9.129(2), b = 13.867(2), c = 17.934(5) Angstrom, beta = 117.52(2)degrees, Z = 4 and R = 0.0623. The sodium atom is surrounded by six oxygen atoms at distances between 2.363(6) and 2.484(8) Angstrom. The Na ... Na distance is 3.693(7) Angstrom. The compound has an extended structure forming layers, held together by H bonds. K(Cr(phen)(2)(C2O4)(2)). DMF . 0.5H(2)O (2) is monoclinic, P2(1)/n,a = 11.298(2), b = 14.048(5), c = 14.240(5) Angstrom, beta = 108.19(2)C, Z = 4 and R = 0.0647. The material also possesses an extended 2D structure, but quite different from the one of the sodium compound. The coordination number around the K atom is 6 with K-O distances between 2.663(13) and 2.920(9) Angstrom. The K ... K distance is 3.939(9) C. The other crystals 4-NH(3)py[Cr(phen)(2)(C2O4)(2)]. 2H(2)O (3), N-(n-butyl)(4)[Cr(phen)(2)(C2O4)(2)] (4), and PPh4[Cr(phen)(C2O4)(2)] (5) have simple discrete ionic structures. Crystal 3 is monoclinic, Cc, a = 17.282(5), b = 15.037(3), c = 9.563(2) Angstrom, beta = 115.25(2)C, Z = 4, and R = 0.0386. The ions are held together by an extensive hydrogen bonding system involving the two molecules of water located in the lattice. Crystal 4 is monoclinic, P2(1)/c, a = 12.329(3), b = 14.471(3), c = 18.181(3) +, beta = 97.75(2)C, Z = 4, and R-1 = 0.076 and finally, 5 is monoclinic, P2(1)/c, a = 13.231(2), b = 14.410(2), c = 18.758(4) Angstrom, beta = 106.00(1)degrees, Z = 4, and R-1 = 0.0517.