Equatorial Oxygen Atoms Research Articles

Synthesis, crystal structure and Hirshfeld surface analysis of a new copper(II) complex based on diethyl 2,2'-(4H-1,2,4-triazole-3,5-di-yl)di-acetate.

The title compound, bis-[μ-2,2'-(4H-1,2,4-triazole-3,5-di-yl)di-acetato]-bis-[di-aqua-copper(II)] dihydrate, [Cu2(C6H5N3O4)2(H2O)4]·2H2O, is a dinuclear octa-hedral CuII triazole-based complex. The central copper atoms are hexa-coordinated by two nitro-gen atoms in the equatorial positions, two equatorial oxygen atoms of two carboxyl-ate substituents in position 3 and 5 of the 1,2,4-triazole ring, and two axial oxygen atoms of two water mol-ecules. Two additional solvent water mol-ecules are linked to the title mol-ecule by O-H⋯N and O⋯H-O hydrogen bonds. The crystal structure is built up from the parallel packing of discrete supra-molecular chains running along the a-axis direction. Hirshfeld surface analysis suggests that the most important contributions to the surface contacts are from H⋯O/O⋯H (53.5%), H⋯H (28.1%), O⋯O (6.3%) and H⋯C/C⋯H (6.2%) inter-actions. The crystal studied was twinned by a twofold rotation around [100].

Flux Crystal Growth, Structure, and Optical Properties of LiLa3Ti2S3O6: An Oxysulfide Phase Derived from K2NiF4-Type Structure.

Single crystals of a new titanium oxysulfide, LiLa3Ti2S3O6, were grown from a KI molten salt. Single-crystal X-ray diffraction analysis revealed that LiLa3Ti2S3O6 crystallizes in the space group Pnma with lattice parameters of a = 11.7319(4) Å, b = 3.94787(14) Å, and c = 20.6885(6) Å. In this structure, the one-dimensional chains of corner-sharing TiO5S octahedra are further corner-linked via equatorial and apical oxygen atoms to form unique corrugated two-dimensional perovskite-type layers in the ab plane with one octahedral thickness. These layers were intervened along the c-axis by the LaS rock-salt layers corrugated concomitantly with the perovskite-type layers, and LiO2S2 tetrahedral chains were located between these two types of two-dimensional layers. LiLa3Ti2S3O6 can be viewed as a modified K2NiF4-type structure with TiO5S octahedral layers stacked in a zigzag manner along the c axis. The oxysulfide has a direct-type band gap of 1.85 eV, based on UV-vis-NIR diffuse reflectance measurements. First-principles calculations showed that the conduction band minimum mainly consists of Ti 3d orbitals, and the valence band maximum consists of S 3p, O 2p, and Li 2s orbitals. The electronic structures near the Fermi level are similar to those of the structurally related photocatalytic oxysulfides Y2Ti2S2O5 and La5Ti2CuS5O7.

Chemically anchoring molybdenum atoms onto micropore-rich VN nanosheet for boosted nitrogen electro-fixation via hydrogen bonds

The hydrogenation of N2 is critical for nitrogen reduction reaction (NRR) and heavily relies on weak van der Waals forces, which leads to sluggish N2 activation. Herein, we put forward a hydrogen-bonding (H-bonding) strategy to promote N2 hydrogenation via chemically anchoring tetrahedron molybdate ([MoO4]) moieties onto micropore-rich VN nanosheets (Mo-VN). In Mo-VN, monodispersed Mo atoms linked with three equivalent end-on oxygen atoms anchor in VN matrix through bridging oxygen with O─Mo─O─V─N configurations, which strongly drive the proton-hydrogen migrate to the adsorbed N2 by H-bonding with NN-H···O-Mo formation, facilitating N2 adsorption and activation. The obtained Mo-VN catalysts deliver an excellent and stable catalytic performance for NH3 production, surpassing most N-containing catalysts. Experimental and theoretical calculations results confirm that the O─Mo─O─V─N bonding environment accelerates all hydrogenation steps of N2 and enables efficient nitrogen activation, which efficiently promote the intrinsic NRR activity and stability. This work opens up a new avenue for developing high-efficiency catalysts through H-bonding strategy.

Synthesis, structures and properties of novel tricyclic tetraalkylphosphoranes with hydrogen and chlorine atoms at the apical position

A tetraalkylhydrophosphorane having three methylene groups instead of three equatorial oxygen atoms of a 1-hydro-5-carbaphosphatrane was synthesized by the reaction of the corresponding phosphonium salt with LiAlH4. A tetraalkylchloro- phosphorane was obtained from the phosphonium salt. Their X-ray crystallographic analyses showed that they have nearly ideal trigonal bipyramidal structures. Their bond lengths and angles as well as apical coupling constants showed that they have usual apicophilic arrangement. The tetraalkylhydrophosphorane gave two phosphine oxides, one of which was formed via homolytic bond cleavage of P-methine carbon bonds under daylight. Another phosphine oxide was estimated to be its isomer formed via the P-benzyl bond cleavage. The reaction of the chlorophosphorane with Me3Al afforded the corresponding pentaalkylphosphorane with the methyl group.

Involvement of 5f Orbitals in the Covalent Bonding between the Uranyl Ion and Trialkyl Phosphine Oxide: Unraveled by Oxygen K-Edge X-ray Absorption Spectroscopy and Density Functional Theory.

Monodentate organophosphorus ligands have been used for the extraction of the uranyl ion (UO22+) for over half a century and have exhibited exceptional extractability and selectivity toward the uranyl ion due to the presence of the phosphoryl group (O═P). Tributyl phosphate (TBP) is the extractant of the world-renowned PUREX process, which selectively recovers uranium from spent nuclear fuel. Trialkyl phosphine oxide (TRPO) shows extractability toward the uranyl ion that far exceeds that for other metal ions, and it has been used in the TRPO process. To date, however, the mechanism of the high affinity of the phosphoryl group for UO22+ remains elusive. We herein investigate the bonding covalency in a series of complexes of UO22+ with TRPO by oxygen K-edge X-ray absorption spectroscopy (XAS) in combination with density functional theory (DFT) calculations. Four TRPO ligands with different R substituents are examined in this work, for which both the ligands and their uranyl complexes are crystallized and investigated. The study of the electronic structure of the TRPO ligands reveals that the two TRPO molecules, irrespective of their substituents, can engage in σ- and π-type interactions with U 5f and 6d orbitals in the UO2Cl2(TRPO)2 complexes. Although both the axial (Oyl) and equatorial (Oeq) oxygen atoms in the UO2Cl2(TRPO)2 complexes contribute to the X-ray absorption, the first pre-edge feature in the O K-edge XAS with a small intensity is exclusively contributed by Oeq and is assigned to the transition from Oeq 1s orbitals to the unoccupied molecular orbitals of 1b1u + 1b2u + 1b3u symmetries resulting from the σ- and π-type mixing between U 5f and Oeq 2p orbitals. The small intensity in the experimental spectra is consistent with the small amount of Oeq 2p character in these orbitals for the four UO2Cl2(TRPO)2 complexes as obtained by Mulliken population analysis. The DFT calculations demonstrate that the U 6d orbitals are also involved in the U-TRPO bonding interactions in the UO2Cl2(TRPO)2 complexes. The covalent bonding interactions between TRPO and UO22+, especially the contributions from U 5f orbitals, while appearing to be small, are sufficiently responsible for the exceptional extractability and selectivity of monodentate organophosphorus ligands for the uranyl ion. Our results provide valuable insight into the fundamental actinide chemistry and are expected to directly guide actinide separation schemes needed for the development of advanced nuclear fuel cycle technologies.

Uranium (VI) Adsorbate Structures on Portlandite [Ca(OH)2] Type Surfaces Determined by Computational Modelling and X-ray Absorption Spectroscopy

Portlandite [Ca(OH)2] is a potentially dominant solid phase in the high pH fluids expected within the cementitious engineered barriers of Geological Disposal Facilities (GDF). This study combined X-ray Absorption Spectroscopy with computational modelling in order to provide atomic-scale data which improves our understanding of how a critically important radionuclide (U) will be adsorbed onto this phase under conditions relevant to a GDF environment. Such data are fundamental for predicting radionuclide mass transfer. Surface coordination chemistry and speciation of uranium with portlandite [Ca(OH)2] under alkaline groundwater conditions (ca. pH 12) were determined by both in situ and ex situ grazing incidence extended X-ray absorption fine structure analysis (EXAFS) and by computational modelling at the atomic level. Free energies of sorption of aqueous uranyl hydroxides, [UO2(OH)n]2–n (n = 0–5) with the (001), (100) and (203) or (101) surfaces of portlandite are predicted from the potential of mean force using classical molecular umbrella sampling simulation methods and the structural interactions are further explored using fully periodic density functional theory computations. Although uranyl is predicted to only weakly adsorb to the (001) and (100) clean surfaces, there should be significantly stronger interactions with the (203/101) surface or at hydroxyl vacancies, both prevalent under groundwater conditions. The uranyl surface complex is typically found to include four equatorially coordinated hydroxyl ligands, forming an inner-sphere sorbate by direct interaction of a uranyl oxygen with surface calcium ions in both the (001) and (203/101) cases. In contrast, on the (100) surface, uranyl is sorbed with its axis more parallel to the surface plane. The EXAFS data are largely consistent with a surface structural layer or film similar to calcium uranate, but also show distinct uranyl characteristics, with the uranyl ion exhibiting the classic dioxygenyl oxygens at 1.8 Å and between four and five equatorial oxygen atoms at distances between 2.28 and 2.35 Å from the central U absorber. These experimental data are wholly consistent with the adsorbate configuration predicted by the computational models. These findings suggest that, under the strongly alkaline conditions of a cementitious backfill engineered barrier, there would be significant uptake of uranyl by portlandite to inhibit the mobility of U(VI) from the near field of a geological disposal facility.

C-H⋯O contacts in the crystal structure of 1,3-di-thiane 1,1,3,3-tetra-oxide.

The crystal structure of 1,3-di-thiane 1,1,3,3-tetra-oxide, C4H8O4S2, has been determined to examine the inter-molecular C-H⋯O hydrogen bonds in a small mol-ecule with highly polarized hydrogen atoms. The crystals are monoclinic, space group Pn, with a = 4.9472 (5), b = 9.9021 (10), c = 7.1002 (7) Å and β = 91.464 (3)° with Z = 2. The mol-ecules form two stacks parallel to the a axis with the molecules being one a translation distance from each other. This stacking involves axial hydrogen atoms on one mol-ecule and the axial oxygen atoms on the adjacent mol-ecule in the stack. None of these C-H⋯O contacts is particularly short (all are > 2.4 Å). The many C-H⋯O contacts between the two stacks involve at least one equatorial hydrogen or oxygen atom. Again, no unusually short contacts are found. The whole crystal structure basically consists of a complex network of C-H⋯O contacts with no single, linear C-H⋯O contacts, only contacts that involve two (bifurcated), and mostly three or four neighbors.

Stabilization of Plutonium(V) Within a Crown Ether Inclusion Complex

Crystalline coordination complexes of actinides, especially in atypical oxidation states, are not only fundamentally important for expanding the notably limited knowledge on the bonding nature of a...

Stable and reproducible supramolecular motif in the crystal structure of sulfonamides of the benzothiazine series fused to an epoxybornane moiety

The crystal structures of four sulfonamides of the benzothiazine series, fused to an epoxidized norbornane moiety and containing various substituents in the para position of the aromatic ring, were determined. Despite the different volume and acceptor/donor properties of substituents (hydrogen, a methyl group, a cyano group, fluorine), these compounds form isostructural crystals. The main supramolecular motif of these crystals consists of heterochiral chains, which run along a glide plane and are formed via hydrogen bonds between the axial oxygen atom of the sulfonyl group and the amino-group nitrogen atom. The chains are cross-linked to form a crystal structure through C—H…O interactions between the hydrogen atom at the epoxide ring and the equatorial sulfonyl oxygen atom.

Structural disorder and magnetic correlations driven by oxygen doping in Nd2NiO4+δ ( δ∼0.11 )

We investigated the influence of oxygen over-stoichiometry on apical oxygen disorder and magnetic correlations in Nd2NiO4+d (d~0.11) in the temperature range of 2-300 K by means of synchrotron x-ray powder diffraction, neutron single crystal and powder diffraction studies, combined with macroscopic magnetic measurements. In the investigated temperature range, the compound crystalizes in a tetragonal commensurate structure with the P42/ncm space group with excess oxygen atoms occupy the 4b (3/4 1/4 1/4) interstitial sites, coordinated by four apical oxygen atoms. Large and anisotropic thermal displacement parameters are found for equatorial and apical oxygen atoms, which are strongly reduced on an absolute scale compared to the Nd2NiO4.23 phase. Maximum Entropy analysis of the neutron single crystal diffraction data uncovered anharmonic contributions to the displacement parameters of the apical oxygen atoms, toward the nearest vacant 4b interstitial site, related to the phonon assisted oxygen diffusion mechanism. Macroscopic magnetization measurements and neutron powder diffraction studies reveal long-range antiferromagnetic ordering of the Ni-sublattice at TN ~ 53 K with a weak ferromagnetic component along the c-axis, while the long-range magnetic ordering of the Nd-sublattice occurs below 10 K. Temperature dependent neutron diffraction patterns show the appearance of a commensurate magnetic order at TN with the propagation vector k = (100) and the emergence of an additional incommensurate phase below 30 K, while both phases coexist at 2 K. The commensurate magnetic structure is best described by the P42/nc`m` Shubnikov space group. Refined magnetic moments of the Ni and Nd-sites at 2 K are 1.144(76) muB and 1.632(52) muB respectively. A possible origin of the incommensurate phase is discussed and a tentative magnetic phase diagram is proposed.

Cobalt spin states investigation of Ruddlesden-Popper La2−xSrxCoO4, using X-ray diffraction and infrared spectroscopy

Ruddlesden-Popper (RP) La2−xSrxCoO4 (x = 0.7, 0.9, 1.1, 1.3) were synthesized by a modified sol-gel route. The synthesized samples were characterized by XRD, FE-SEM technique, iodometric titration, FT-FIR spectroscopy and VSM analysis. The variation of Co-O bond length obtained from Rietveld refinements and the related peak shifts in the FT-FIR spectra showed that Co3+ has both LS and IS spin states. It is found that the population of Co3+ in the LS state decreases and IS state increases with increasing Sr concentration. Jahn-Teller effect was identified in the FT-FIR absorption bands, corresponding to the vibration modes of Co bonds with the apical and equatorial oxygen atoms. The ferromagnetic characteristic of La0.7Sr1.3CoO4, obtained by VSM, revealed the increase of Co3+ IS population by Sr doping, in agreement with XRD and FT-FIR results. The shift and split of the IR absorption bands with the change in the structural parameters are proposed to be an applicable tool to probe the spin states and Jahn-Teller effect in La2−xSrxCoO4 compounds.

Crown ether complexes of actinyls: a computational assessment of AnO2(15-crown-5)2+ (An = U, Np, Pu, Am, Cm).

For further fundamental understanding of the nature and extent of covalency in actinyl-ligand bonding, and the benefits that this may have in the design of new ligands for nuclear waste separation, there is burgeoning interest in the nature of actinyl complexes with polydentate or multiple-point-donor ligands, such as crown ethers. There are few cases of structurally authenticated molecular actinyl-crown bonds under ambient conditions. We report here the computational characterization of AnO22+-(15-crown-5) complexes, where An = U, Np, Pu, Am, and Cm, and 15-crown-5 is the cyclic polyether ligand with five ether oxygen atoms. In the gas-phase complex, the actinyl group is located inside of the crown ether, tilted slightly out of the plane of the five equatorial oxygen atoms that coordinate the actinide metal center. The actinyl-cyclic ether complexes are found to exhibit a conventional conformation, with typical An-Oaxial and An-Oequatorial distances and angles. A striking result is the enhanced stability of the insertion complex for UO22+versus NpO22+, PuO22+, AmO22+ and CmO22+, which is evaluated in the context of An-O binding strengths (esp. bonding covalency), and may have ramifications for the utility of actinyl-crown complexes in separation applications.

Oxygen Displacement in Cuprates under Ionic Liquid Field-Effect Gating

We studied structural changes in a 5 unit cell thick La1.96Sr0.04CuO4 film, epitaxially grown on a LaSrAlO4 substrate with a single unit cell buffer layer, when ultra-high electric fields were induced in the film by applying a gate voltage between the film (ground) and an ionic liquid in contact with it. Measuring the diffraction intensity along the substrate-defined Bragg rods and analyzing the results using a phase retrieval method we obtained the three-dimensional electron density in the film, buffer layer, and topmost atomic layers of the substrate under different applied gate voltages. The main structural observations were: (i) there were no structural changes when the voltage was negative, holes were injected into the film making it more metallic and screening the electric field; (ii) when the voltage was positive, the film was depleted of holes becoming more insulating, the electric field extended throughout the film, the partial surface monolayer became disordered, and equatorial oxygen atoms were displaced towards the surface; (iii) the changes in surface disorder and the oxygen displacements were both reversed when a negative voltage was applied; and (iv) the c-axis lattice constant of the film did not change in spite of the displacement of equatorial oxygen atoms.

Uranium(VI) Scavenging by Amorphous Iron Phosphate Encrusting Sphaerotilus natans Filaments

U(VI) sorption to iron oxyhydroxides, precipitation of phosphate minerals, as well as biosorption on bacterial biomass are among the most reported processes able to scavenge U(VI) under oxidizing conditions. Although phosphates significantly influence bacterially mediated as well as iron oxyhydroxide mediated scavenging of uranium, the sorption or coprecipitation of U(VI) with poorly crystalline nanosized iron phosphates has been scarcely documented, especially in the presence of microorganisms. Here we show that dissolved U(VI) can be bound to amorphous iron phosphate during their deposition on Sphaerotilus natans filamentous bacteria. Uranium LIII-edge EXAFS analysis reveals that the adsorbed uranyl ions share an equatorial oxygen atom with a phosphate tetrahedron of the amorphous iron phosphate, with a characteristic U-P distance of 3.6 Å. In addition, the uranyl ions are connected to FeO6 octahedra with U-Fe distances at ~3.4 Å and at ~4.0 Å. The shortest U-Fe distance corresponds to a bidentate edge-sharing complex often reported for uranyl adsorption onto iron oxyhydroxides, whereas the longest U-Fe and U-P distances can be interpreted as a bidentate corner-sharing complex, in which two adjacent equatorial oxygen atoms are shared with the vertices of a FeO6 octahedron and of a phosphate tetrahedron. Furthermore, based on these sorption reactions, we demonstrate the ability of an attached S. natans biofilm to remove uranium from solution without any filtration step.

Effect of silicate on U(VI) sorption to γ-Al2O3: Batch and EXAFS studies

The effect of soluble silicate on the sorption of U(VI) to γ-Al2O3 was investigated by batch experiments and extended X-ray absorption fine structure (EXAFS) method. The presence of silicate enhanced the sorption of U(VI) on γ-Al2O3 surface and the sorption was attributed to inner-sphere surface complexation. The structure of the adsorbed U(VI) and silicate on γ-Al2O3 was investigated in the analysis of EXAFS spectra. The fitting of the experimental EXAFS data was obtained by including two uranium coordination shells with 2 axial (Oax) and 5 equatorial (Oeq) oxygen atoms at 1.79±0.02 and 2.43±0.02Å, respectively, and the third coordination shells with Al atom at ∼3.35Å. Silicate contributed to the formation of ternary inner-sphere surface complexes, acting as “bridge” between U(VI) and γ-Al2O3 and enhanced the sorption of U(VI). The observations suggested that the interactions between U(VI) and silicate were important in controlling U(VI) retention.

Study of the molecular and crystal structure of a new coordination polymer of copper(II) nitrate with 4,4,10,10-tetramethyl-1,3,7,9-tetraazospiro[5.5]undecane-2,8-dione

A coordination polymer {[Cu(C11H20N4O2)2(H2O)]2+·2(NO3−)}n (I) is synthesized and analyzed using single-crystal XRD. The crystals are monoclinic: space group P2/c, a = 12.5237(6) A, b = 7.3310(3) A, c = 16.8926(8) A, β = 92.569(4)°, V = 1549.38(13) A3, ρcalc = 1.47 g/cm3, and Z = 2. The copper atom is in a special position in the second-order axis. The coordination polyhedron of the metal is a trigonal bipyramid. In the axial direction, it is coordinated by two oxygen atoms O(1) of the organic ligand molecules connected by the symmetry operation [−x, y, 0.5-z]; the angle O(1)Cu(1)O(1)i is 175.16(15)°. In the equatorial direction, the copper atom is coordinated by oxygen atoms O(2) of two ligand molecules connected with the reference molecule by the symmetry operations [−x, y, 0.5-z] and [x, 1-y, −0.5+z] and the water molecule O(6) in a special position on the twofold axis. The OCuO angles between the equatorial oxygen atoms are 96.80(16)–131.60(8)°, and those between the axial and equatorial atoms are 87.58(8)-91.60(10)°. It is noteworthy that the length of the Cu-O(1) bond (1.955(2) A) with the axial carbonyl oxygen atom is somewhat shorter than the bond (2.060(3) A) with the equatorial atom. Nitrate anions are outside the coordination sphere of the metal. The Cu…Cu distance in the polymer is 8.33 A. To confirm the purity of the sample of I, the powder X-ray pattern is refined by the Rietveld method; the lattice parameters at room temperature are: a = 12.535(4) A, b = 7.3161(13) A, c = 16.841(5) A, β = 92.11(2)°, and V = 1543.4(7) A3.

Tris(organotin)tungstogermanate, a Sandwich Organometallic Derivative of a Keggin‐Type Polyoxometalate: Synthesis and DFT Study

AbstractA phenyltin‐containing Keggin‐based polyoxometalate has been synthesised and characterised by elemental analysis, infrared and electronic spectroscopy, and multinuclear NMR spectroscopy. Structural data, complemented by DFT calculations, suggests that three phenyltin groups connect two [α‐GeW9O34]10– moieties to form the [(C6H5SnOH)3(α‐GeW9O34)2]14– anion. Each tin atom displays a distorted‐octahedral environment, composed of two sets of equatorial oxygen atoms from two edge‐sharing WO6 octahedra of each [α‐GeW9O34]10– group, and one phenyl and one OH group in the axial positions. The DFT studies lend support to the experimental proposal of the molecular structure of this polyoxometalate. The similar energy of the limiting arrangements of phenyl groups demonstrates how their fluxionality occurs as a dynamical process in solution and explains the disorder in the solid.

Single-crystal EPR study of three radiation-induced defects (Al–O2 3−, Ti3+ and W5+) in stishovite

Single-crystal electron paramagnetic resonance spectra of electron-irradiated stishovite, measured at temperatures from 3.5 to 294 K, reveal three S = 1/2 radiation-induced defects: an aluminum-associated oxygen hole center and two nd 1 centers (Ti3+ and W5+). The aluminum-associated oxygen hole center, characterized by an orthorhombic site symmetry, coaxial matrices of the electronic Zeeman g, nuclear hyperfine A(27Al) and nuclear quadrupole P(27Al), and the orientation of the g-minimum axis along an O–O direction and those of the unique A(27Al) and P(27Al) axes perpendicular to the O–O direction, is an Al–O2 3− center, with the unpaired electron equally distributed on two equatorial oxygen atoms of a substitutional Al3+ ion at the octahedral Si site. Fully optimized Al-doped structure, theoretical 27Al nuclear hyperfine and quadrupole coupling constants and directions, and 3D spin densities from periodic hybrid density functional theory calculations provide further support for this structural model. Spin Hamiltonian parameters of the Ti3+ and W5+ centers, which are confirmed by their diagnostic 47Ti, 49Ti and 183W hyperfine structures, arise from electron trapping on substitutional Ti4+ and W6+ ions at the octahedral Si site.

Structural study of the copper(II)–enrofloxacin metallo-antibiotic

The structure of [Cu(erx)2(H2O)2] complex was assessed using copper K-edge X-ray absorption spectroscopy (XAS) through X-ray absorption near edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) combined with EPR spectroscopy. A Jahn–Teller distorted octahedra was evidenced for Cu2+ geometry. Four equatorial oxygen atoms from two enrofloxacin ligands were found with Cu–Oeq distances of 1.93Å (±0.02). The coordination was completed by two water molecules in axial position at an average distance of 2.11Å.

Syntheses, Structural, and Spectroscopic Properties of Copper(II) Complexes of Constrained Macrocyclic Ligands

AbstractThe complexes [Cu(L1)(H2O)2](BF4)2·2H2O (1) [L1 = 5, 16‐dimethyl‐2, 6, 13, 17‐tetraazatricyclo(14, 4, 01.18,07.12)docosane] and 0.5[Cu(L2)(NO3)2][Cu(L2)](NO3)2 (2) [L2 = dibenzyl‐5, 16‐dimethyl‐2, 6, 13, 17‐tetraazatricyclo(14, 4, 01.18,07.12)docosane] were synthesized and characterized by single crystal X‐ray analyses. In these constrained macrocycles, the central copper(II) atoms are in a tetragonally distorted octahedral environment with four nitrogen atoms of the macrocyclic ligands in equatorial positions and oxygen atoms from either water molecules or nitrato groups in axial positions. The macrocyclic ligands in both complexes adopt the most stable trans‐III conformation. The Cu–N distances [1.999(7)–2.095(7) Å] are typical for such complexes, but the axial ligands are weakly coordinating Cu–OH2 bonds [2.693(3) Å] and Cu–ONO2 bonds [2.873(7) Å] due to the combination of the pseudo Jahn–Teller effect and strong in‐plane ligand field. The crystals are stabilized by a three‐dimensional network by hydrogen bonds that are formed among the secondary nitrogen hydrogen atoms, oxygen atoms of water molecules, fluorine atoms of BF4–, and oxygen atoms of NO3–. The electronic absorption and IR spectroscopic properties are also discussed.