Crystal structures of {[Cu(Lpn)₂][Fe(CN)₅(NO)]-H₂O}n and {[Cu(Lpn)₂]₃[Cr(CN)₆]₂·5H₂O}_n [where Lpn = (R)-propane-1,2-diamine]: Two heterometallic chiral cyanide-bridged coordination polymers

The title compounds, catena-poly[[[bis[(R)-propane-1,2-diamine-κ² N,N′]-copper(II)]-μ-cyanido-κ² N: C-[tris(cyanido-κC)(nitroso-κN) iron(III)]-μ-cyan-ido-κ²C: N] monohydrate], {[Cu(Lpn)₂][Fe(CN)₅(NO)]⋯H₂O}_n, (I), and poly-[[hexa-μ-cyanido-κ¹²C: N-hexacyanido-κ⁶C-hexakis[(R)-propane-1,2-diamine-κ²N,N′]dichromium(III) tricopper(II)] pentahydrate], {[Cu(Lpn)₂]₃[Cr(CN)₆]₂·-5H₂O}_n, (II) [where Lpn = (R)-propane-1,2-diamine, C₃H₁₀N₂], are new chiral cyanide-bridged bimetallic coordination polymers. The asymmetric unit of compound (I) is composed of two independent cation-anion units of {[Cu(Lpn)₂][Fe(CN)₅)(NO)]} and two water molecules. The Fe^III atoms have distorted octahedral geometries, while the Cu^II atoms can be considered to be pentacoordinate. In the crystal, however, the units align to form zigzag cyanide-bridged chains propagating along [101]. Hence, the Cu atoms have distorted octahedral coordination spheres with extremely long semicoordination Cu - N(cyanido) bridging bonds. The chains are linked by O - H⋯ N and N - H⋯N hydrogen bonds, forming two-dimensional networks parallel to (010), and the networks are linked via N - H⋯O and N - H⋯N hydrogen bonds, forming a three-dimensional framework. Compound (II) is a two-dimensional cyanide-bridged coordination polymer. The asymmetric unit is composed of two chiral {[Cu(Lpn)₂][Cr(CN)₆]} anions bridged by a chiral [Cu(Lpn)₂]²⁺ cation and five water molecules of crystallization. Both the Cr^III atoms and the central Cu^II atom have distorted octahedral geometries. The coordination spheres of the outer Cu atoms of the asymmetric unit can be considered to be pentacoordinate. In the crystal, these units are bridged by long semicoordination Cu - N(cyanide) bridging bonds forming a two-dimensional network, hence these Cu^II atoms now have distorted octahedral geometries. The networks, which lie parallel to (101), are linked via O - H⋯ O, O - H⋯ N, N - H⋯O and N - H⋯N hydrogen bonds involving all five non-coordinating water molecules, the cyanide N atoms and the NH₂ groups of the Lpn ligands, forming a three-dimensional framework.