Bis(nitrato-κO)(1,4,8,11-tetraazacyclotetradecane-κ4 N)zinc(II) methanol monosolvate

The coordination of the central ZnII atoms in the two different Zn-cyclam units is distorted octahedral.

The two Zn II atoms in the crystal structure of the title complex, [Zn(NO 3 ) 2 (C 10 H 24 N 4 )]ÁCH 3 OH, have a distorted octahedral coordination sphere, defined by 1,4,8,11-tetraazacyclotetradecane (cyclam) N atoms in the equatorial plane and nitrate O atoms in the axial sites. The conformation of the cyclam is trans-III (R, R, S, S), which is typical for metal-cyclam complexes. Nitrate anions are involved in intra-and intermolecular hydrogen bonding with the N-H groups of the Zn II -cyclam unit. Together with the methanol solvent molecule, the hydrogen-bonding network connects the Zn II -cyclam units into ribbons running parallel to the a axis.

Structure description
Cyclam is a well-known macrocyclic polyamine and water-soluble ligand that can strongly chelate transition-metal cations. As a result, various cyclam derivatives and metal complexes have been synthesized, and their crystal structures have been described. The crystal structure of the title zinc nitrate complex, on the other hand, is the first reported in this context. We anticipate that, in future, this structural property can be used in the development of new functional materials.
The asymmetric unit of the title complex, [Zn II (C 10 H 24 N 4 = cyclam)](NO 3 ) 2 ÁCH 3 OH, comprises two half-Zn II -cyclam complexes that are centered on Zn1 and Zn2, as well as two nitrate anions that coordinate to each Zn II atom, and a methanol solvent molecule. The two half-Zn II -cyclam complexes are completed by inversion symmetry. Each Zn II atom is coordinated in a planar fashion by the four N atoms of the cyclam ligand. N1, N2, data reports N1 i , and N2 i [symmetry code: (i) 2 À x, 1 À y, 1 À z] define the cyclam plane around Zn1, and nitrate atoms O1 and O1 i coordinate at the axial positions of the resulting distorted octahedron (Fig. 1). For Zn2, the equatorial plane is defined by N3, N4, N3 ii , and N4 ii [symmetry code: (ii) 1 À x, 1 À y, 1 À z], and the axially bound O atoms by O4 and O4 ii (Fig. 2). The coordination environments of the two central Zn II atoms are similar to that of Co(cyclam)Cl 2 (Oba & Mochida, 2015). The conformation of the cyclam structure is trans-III (R, R, S, S) type, which is the most energetically favorable conformation (Bosnich et al., 1965). The conformation is generally consistent with previous reports for metal-cyclam complexes such as Cu II (Emsley et al., 1990), Ni II (Prasad et al., 1987), and Pd II (Hunter et al., 2004). The Zn1-O1 and Zn2-O4 bond lengths are 2.3045 (18) and 2.3233 (19) Å , respectively, which is longer than in the Zn II -nitrate ion (ca 2.0 Å ; Ichimaru et al., 2021;Kinoshita-Kikuta et al., 2021), owing to the hydrogenbonding network detailed below. The N1-Zn1-O1 and N2-Zn1-O1 bond angles are 92.98 (8) and 89.14 (9) , and N3-Zn2-O4 and N4-Zn2-O4 are 91.98 (8) and 87.95 (9) . These angles imply that both Zn II atoms are on the centroid of the plane created by the four cyclam N atoms. However, the two cyclam rings chelating Zn1 and Zn2 have different asymmetric structures: N1-H1 and N2-H2 have synconfigurations, while N3-H3 and N4-H4 have anti-configurations.

Figure 1
The Zn 1I -cyclam complex involving Zn1 and the methanol solvate molecule. Displacement ellipsoids are drawn at the 50% probability level;. C-bound H atoms were omitted for clarity. Gray atom labels represent atoms generated by symmetry expansion (symmetry operation: 2 À x, 1 À y, 1 À z).

Figure 3
Packing view down the b axis of the title complex with displacement ellipsoids drawn at the 50% probability level. Solvent molecules and Cbound H atoms were omitted for clarity. Hydrogen-bonding interactions are shown as dotted lines. [Symmetry codes:

Synthesis and crystallization
Under an argon atmosphere, zinc nitrate hexahydrate (1.5 g, 5 mmol), dissolved in dry methanol (5 ml), was added to a 20 ml dry methanolic solution of cyclam (1.0 g, 5 mmol). The reaction mixture was agitated at room temperature for 2 h before the solvent was evaporated to get a colorless solid. To obtain colorless crystals appropriate for X-ray crystallography, the crude product was dissolved in hot methanol, filtered through a cellulose filter (0.45 mm pore size) and cooled to room temperature (yield 1.7 g, 87%).   Symmetry code: (i) Àx þ 1; Ày þ 1; Àz þ 1.

Figure 4
Packing view down the a axis of the title complex with displacement ellipsoids drawn at the 50% probability level. Solvent molecules and H atoms are omitted for clarity. [Symmetry code: (iii) x, 1 2 À y, À 1 2 + z].

data-1
IUCrData (  where P = (F o 2 + 2F c 2 )/3 (Δ/σ) max = 0.001 Δρ max = 1.01 e Å −3 Δρ min = −0.92 e Å −3 Special details Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes. Refinement. All hydrogen atoms were placed using a geometrical computation.