Powder Diffraction Study of a Coordination Polymer Comprised of Rigid Building Blocks:  [Rh2(O2CCH3)4·μ2-Se2C5H8-Se,Se‘]

The crystal structure of a new hybrid product comprised of two rigid building blocks, namely dirhodium(II) tetraacetate, [Rh2(O2CCH3)4] (1), and 2,6-diselenaspiro[3.3]heptane, Se2C5H8 (2), has been solved ab initio using laboratory source X-ray powder diffraction (XRPD) data. The rigid body refinement approach has been applied to assist in finding an adequate model and to reduce the number of the refined parameters. Complex [Rh2(O2CCH3)4·μ2-Se2C5H8-Se,Se‘] (3) conforms to the triclinic unit cell with lattice parameters of a = 8.1357(4), b = 8.7736(4), and c = 15.2183(8) Å, α = 77.417(3), β = 88.837(3), and γ = 69.276(4)°, V = 989.66(8) Å3, and Z = 2. The centrosymmetric P1̄ space group was selected for calculations. The final values of the reduced wRp, Rp, and χ2 were calculated at 0.0579, 0.0433, and 5.95, respectively. The structure of 3 is a one-dimensional zigzag polymer built on axial Rh···Se interactions at 2.632(6) Å. The 2,6-diselenaspiro[3.3]heptane ligand acts as a bidentate linker bridging dirhodium units via both selenium atoms. The geometrical parameters of individual groups for rigid body refinement have been obtained from X-ray powder data for dirhodium(II) tetraacetate (1) and from single-crystal X-ray diffraction for diselenium molecule 2. The crystal structures of 1 and 2 are reported here for the first time. For 1 indexing based on XRPD data has resulted in the triclinic unit cell P1̄ with lattice parameters of a = 8.3392(7), b = 5.2216(5), and c = 7.5264(6) Å, α = 95.547(10), β = 78.101(6), and γ = 104.714(13)°, V = 309.51(5) Å3, and Z = 1. The final values were wRp = 0.0452, Rp = 0.0340, and χ2 = 1.99. The 1D polymeric motif built on axial Rh···O interactions of the centrosymmetric dirhodium units has been confirmed for the solid-state structure of 1. Compound 2,6-diselenaspiro[3.3]heptane (2) conforms to the monoclinic space group P21/c with the unit cell parameters of a = 5.9123(4), b = 19.6400(13), and c = 5.8877(4) Å, β = 108.5500(10)°, V = 648.15(8) Å3, and Z = 4.