Two Coordination Polymers Created via In Situ Ligand Synthesis Involving C−N and C−C Bond Formation

We report the synthesis and crystal structures of two transition metal-based coordination polymers comprising ligand molecules not included in the original reaction mixtures but instead formed in situ during hydrothermal treatment. Zinc meso-iminodisuccinate hydrate (I), Zn₂(C₈H₇NO₈)·0.57H₂O, formed from zinc acetate and l-aspartic acid, and tetraaquanickel(II) 5,10-dioxo-5,10-dihydro-4,9-dioxa-pyrene-2,7-dicarboxylate (II), Ni(H₂O)₄(C₁₆H₄O₈), formed from nickel acetate and 5-hydroxyisophthalic acid. We show that the formation of I takes place via a fumaric acid intermediate, while the formation of II requires the formation of a new C−C bond. The structure of I consists of weakly interacting sheets, while the structure of II consists of strongly hydrogen-bonded chains. Crystal data:  for I, P2₁/n (14), a = 10.073 Å, b = 9.894 Å, c = 12.053 Å, β = 105.605°, V = 1156.87(13) ų, Z = 4; for II, P1̄ (2), a = 5.011 Å, b = 6.526 Å, c = 12.305 Å, α = 76.868°, β = 84.988°, γ = 87.619°, V = 390.3(4) ų, Z = 1.