The syntheses and spectral and structural characterizations of Zn(II) indomethacin [1-(4-chlorobenzoyl)-5-methoxy2-methyl-1H-indole-3-acetic acid = IndoH] complexes, as different solvent adducts, have been studied. The complexes are unusual in that both monomeric and dimeric complexes are formed and that this is the first example of the same carboxylato ligand binding via both carboxylate oxygen atoms in monomeric and dimeric Zn(II) complexes. The crystal structures of Zn-Indo complexes with N,N-dimethylacetamide (DMA), pyridine (Py), 1-methyl-2-pyrrolidinone (NMP), EtOH, and MeOH as solvent ligands, [Zn-2(Indo)(4)(DMA)(2)]. 2DMA, 1, [Zn-2(Indo)(4)(Py)(2)]. 2H(2)O, 2b, [Zn-2(Indo)(4)(NMP)(2)], 3, cis-[Zn(Indo)(2)(EtOH)(2)], 4, and cis-[Zn(Indo)(2)(MeOH)(2)], 5, were determined. Complexes I, 2b, and 3 crystallize in the triclinic space group P (1) over bar (No. 2): a = 13.628(2) Angstrom, b = 17.462(2) Angstrom, c = 11.078(1) Angstrom, alpha = 99.49(1)degrees, beta = 108.13(1)degrees, gamma = 110.10(1)degrees for 1; a = 13.347(3), b = 16.499(5) Angstrom, c = 10.857(1) Angstrom, alpha = 99.48(2)degrees, beta = 108.25(2)degrees, gamma = 106.24(2)degrees for 2; a = 14.143(3) Angstrom, b = 14.521(2) Angstrom, c = 11.558(2) Angstrom, alpha = 109.07(1)degrees, beta = 90.80(2)degrees, gamma = 116.40(1)degrees for 3. The three complexes exhibit dinuclear paddle-wheel structures with a Zn ... Zn distance of 2.9686(6) Angstrom, Zn-O-RCOO distances of 2.035(2)-2.060(2) Angstrom, and a Zn-O-DMA distance of 1.989(2) Angstrom in 1, a Zn ... Zn distance of 2.969(1) Angstrom, Zn-O-RCOO distances of 2.020(3)-2.049(3) Angstrom, and a Zn-N-Py distance of 2.036(3) Angstrom in 2, and a Zn ... Zn distance of 2.934(1) Angstrom, Zn-O-RCOO distances of 2.009(3)-2.051(3) Angstrom, and a Zn-O-NMP distance of 1.986(3) Angstrom in 3. In these cases, the zinc ions are offset along the z direction such that the L-Zn ... Zn-L moiety is nonlinear, unlike the Cu analogues. Each Zn has a square-pyramidal geometry bridged by four carboxylato ligands in the basal plane with the solvent ligands containing an O- or N-donor atom at the apex. Complexes 4 and 5 are isostructural, with space group C2/c (No. 15). For 4, a = 30.080(2) Angstrom, b = 5.3638(6) Angstrom, c = 24.739(2) Angstrom, beta = 90.342(7)degrees and for 5, a = 29.419(2) Angstrom, b = 5.320(2) Angstrom, c = 24.461(2) Angstrom, beta = 90.840(4)degrees. The Zn resides on a 2-fold axis and the complexes have a distorted cis octahedral structure with Zn-O-RCOO bond lengths of 2.183(3) and 2.169(3) Angstrom, a Zn-O-EtOH bond length of 2.015(3) Angstrom in 4, Zn-O-RCOO bond lengths of 2.195(2) and 2.151(2) Angstrom, and a Zn-O-MeOH bond length of 2.022(3) Angstrom in 5.