Manifestations of noncovalent interactions in the solid state. 3. X-ray crystal structures of [H4(cyclam)][FeCl5(OH2)](Cl)2 and [H4(cyclam)][CF3COO]4, two network hydrogen bonded solids
FeCl2 or FeCl3 react with cyclam (cyclam = 1,4,8,11-tetraazacyclotetradecane) in an acidic medium (4 M HCl) to afford dark orange-red plates of [H4(cyclam)][FeCl5(OH2)](Cl)2 (1). 1 crystallizes in a polar space group (orthorhombic, Pc21b) with a = 10.7730(6), b = 13.3418(10), c = 14.4564(10) Å, V = 2077.84(24) Å3, and Dcalc = 1.68 g cm−3 for Z = 4. Final values of R = 0.031 and Rw = 0.034 were obtained for 1950 independent observed (I > 3σ(I)) reflections. Cyclam reacts with neat trifluoroacetic acid to afford a colourless salt, [H4(cyclam)][CF3COO]4 (2). 2 crystallizes in a centric space group (monoclinic, P21/c), with a = 8.7442(11), b = 10.5121(11), c = 15.2469(20) Å, β = 102.526(15)°, V = 1368.1(3) Å3, and Dcalc = 1.593 g cm−3 for Z = 2. Final values of R = 0.059 and Rw = 0.067 were obtained for 1336 independent observed (I > 3σ(I)) reflections. Extensive interionic hydrogen bonding between the cyclam cations, which adopt exodentate conformations, and anions results in network polymeric hydrogen bonding (1-D for 1, 2-D for 2). The networking in 1 is intrinsically polar because one chloride anion and the [FeCl5(OH2)]2− complex anion are involved in networking between the H4(cyclam)4+ cations. The implications of the crystal structures are discussed from the perspective of rational design of polar solids.