Expanded Porphyrin Exhibiting Off-Centered Out-of-Plane Coordination to Dysprosium

Open AccessCCS ChemistryRESEARCH ARTICLES28 Mar 2024Expanded Porphyrin Exhibiting Off-Centered Out-of-Plane Coordination to Dysprosium Dmitry I. Nazarov, Jorge Labella, Alexey V. Kuzmin, Maxim A. Faraonov, Evgenii N. Ivanov, Salavat S. Khasanov, Tomas Torres, Mikhail K. Islyaikin and Dmitri V. Konarev Dmitry I. Nazarov Federal Research Center of Problems of Chemical Physics and Medicinal Chemistry RAS, 142432 Chernogolovka , Jorge Labella Department of Organic Chemistry, Universidad Autónoma de Madrid, 28049 Madrid , Alexey V. Kuzmin Institute of Solid-State Physics RAS, 142432 Chernogolovka , Maxim A. Faraonov Federal Research Center of Problems of Chemical Physics and Medicinal Chemistry RAS, 142432 Chernogolovka , Evgenii N. Ivanov Research Institute of Macroheterocycles, Ivanovo State University of Chemistry and Technology, 15300 Ivanovo G. A. Krestov Institute of Solution Chemistry of the Russian Academy of Sciences, 153045 Ivanovo , Salavat S. Khasanov Institute of Solid-State Physics RAS, 142432 Chernogolovka , Tomas Torres *Corresponding authors: E-mail Address: [email protected] E-mail Address: [email protected] E-mail Address: [email protected] Department of Organic Chemistry, Universidad Autónoma de Madrid, 28049 Madrid Institute for Advanced Research in Chemical Sciences, Universidad Autónoma de Madrid, 28049 Madrid IMDEA-Nanociencia, 28049 Madrid , Mikhail K. Islyaikin *Corresponding authors: E-mail Address: [email protected] E-mail Address: [email protected] E-mail Address: [email protected] Research Institute of Macroheterocycles, Ivanovo State University of Chemistry and Technology, 15300 Ivanovo G. A. Krestov Institute of Solution Chemistry of the Russian Academy of Sciences, 153045 Ivanovo and Dmitri V. Konarev *Corresponding authors: E-mail Address: [email protected] E-mail Address: [email protected] E-mail Address: [email protected] Federal Research Center of Problems of Chemical Physics and Medicinal Chemistry RAS, 142432 Chernogolovka https://doi.org/10.31635/ccschem.024.202303824 SectionsSupplemental MaterialAboutAbstractPDF ToolsAdd to favoritesDownload CitationsTrack Citations ShareFacebookTwitterLinked InEmail The complexation of high-spin lanthanides to porphyrinoids is a powerful strategy for the development of advanced molecular magnets. In this context, the use of expanded porphyrinoids remains elusive since their coordination chemistry is challenging to control. Herein, taking inspiration from on-surface chemistry, we explored the coordination of Dy3+ to a six-membered porphyrinoid, namely, the hemihexaphyrazine H3Hhp. Remarkably, we observed the selective formation of a mono-nuclear off-centered, out-of-plane H2Hhp-Dy3+ complex when performing the complexation under reductive conditions. During this reaction, the oxidation state of the macrocycle did not change. Employing X-ray diffraction analysis, we found that the coordination number of Dy in this complex was 8. The macrocycle cocrystallized with decamethylcobaltocene (Cp2*Co) molecules, giving rise to a well-ordered solid-state packing, governed by π–π interactions. As a result of this organization, a small magnetic coupling between the neighboring molecules was observed. All in all, this work provides key insights into the coordination of magnetically active metals with expanded porphyrinoids, thus motivating the development of advanced spintronic devices. Download figure Download PowerPoint Introduction Single molecule magnetism offers attractive routes toward engineering advanced spintronic devices.1 High-performing single molecule magnets (SMMs) can be readily obtained by complexing paramagnetic metal centers into π-conjugated macrocycles.2 In this context, lanthanide3+ porphyrinoids have been extensively investigated by virtue of their multiple advantages such as high blocking temperatures and ultrahard magnetic behaviors.3–6 Due to their robust tetradentate character, porphyrins (Ps) and phthalocyanines (Pcs) have dominated this field, leading to the development of numerous SMMs with varying sizes, shapes, and supramolecular arrangements in which the magnetic response and spin–orbit coupling can be fine-tuned simply by changing the metallated Ln3+ cation.7–9 Nevertheless, the exploration of SMMs based on porphyrinoids presenting more than four coordination points would open the door to exotic structures, leading to unconventional magnetic responses. Expanded porphyrinoids are analogs of Ps and Pcs featuring larger cores.10–12 These derivatives are known for exhibiting a rich, but at the same time complex, coordination chemistry, whereby multiple metals can be accommodated in their inner cavities, separately or even simultaneously.7,13 By presenting five, six, or more coordinating atoms, expanded porphyrinoids can efficiently satisfy the tendency of earth-rare metals to present high-coordination numbers. Examples include texaphyrins, which have proven to be useful ligands for lanthanides (e.g., Gd, Ce, Pr, Nd, Sm, Eu, and more)14 or dipyriamethyrins, which can stabilize several actinoid metals such as Th, U, and Np.15 However, despite their envisioned potential, the coordination of magnetically active metals with expanded Ps focused on developing SMMs remains elusive. This is primarily ascribed to the fact that very little is still known about the coordination chemistry of these compounds with Ln3+ metals. Thus, establishing fundamental insights in that direction is a crucial step for the development of expanded Ps in molecular magnetism. On a metallic surface, the dimensionality of a given reaction is reduced from three to two.16,17 In principle, this would simplify the outcome of a given reaction, at least from a structural standpoint. Based on this premise, we envisioned that on-surface chemistry could be employed to provide initial insights into reactions with high complexity, which could then be extrapolated to in-solution methodologies. Keeping this idea in mind, in 2017, some of us explored the on-surface coordination of Dy,18 a metal widely used in the preparation of SMMs, with an expanded porphyrin, namely 2,3,5,10,12,13,15,20,22,23,25,30-dodecaazahexaphyrin (H3Hhp) (Figure 1b).19–22 In this work, a H3Hhp monolayer was formed on Au (111), and subsequently exposed to a flux of dysprosium atoms. Remarkably, efficient macrocycle metalation was observed after annealing, leading to an unusual off-centered Dy-H3Hhp coordination complex. Figure 1 | (a) Reported four-membered porphyrinoid-Dy3+ complexes (top) and on-surface synthesized Dy-H3Hhp complex. (b) Off-centered out-of-plane Dy-H3Hhp complex synthesized in solution in this work. Download figure Download PowerPoint Hereby, inspired by the intriguing results observed on metallic surfaces, we explored the formation of Dy-H3Hhp complexes in solution. Remarkably, we observed that the reaction of H3Hhp with Dy3+ precursor led to the formation of 1, a mononuclear Dy-H2Hhp complex wherein the Dy atom exhibited an off-centered out-of-plane coordination to the porphyrinoid, similar to previous on-surface observation. We then evaluated the impact of Dy coordination on the electronic and structural properties of the H3Hhp macrocycle both experimentally and theoretically. Interestingly, binuclear complexes were not found, despite using up to three equivalents of the Dy source. The origin of this finding was unveiled through theoretical calculations. It should be noted that a typical approach involved exploring a reaction in a solution before applying it to the on-surface methods. Therefore, this work serves as a paradigmatic example of how on-surface chemistry can inspire solution chemistry. Experimental Methods Instrumentation and materials UV–visible–near-infrared (NIR) spectra were measured in KBr pellets with a PerkinElmer Lambda 1050 spectrometer (PerkinElmer, USA) in the 250–2500 nm range. Fourier transform infrared (FT-IR) spectra were obtained in KBr pellets with a PerkinElmer Spectrum 400 spectrometer (400–7800 cm−1; PerkinElmer, USA). Electron paramagnetic resonance (EPR) spectra were recorded for a polycrystalline sample of 1 from room temperature (RT) down to liquid helium temperature with a JEOL JES-TE 200 X-band ESR spectrometer (JEOL, Japan) equipped with a JEOL ES-CT470 cryostat. A Quantum Design MPMS-XL SQUID magnetometer (Quantum Design, UK) was used to measure static magnetic susceptibility of 1 at 1 kOe magnetic field in cooling and heating conditions in the 300–1.9 K range. A sample holder contribution was subtracted from the experimental values. Curie constant (C), Weiss temperature (Θ), and temperature-independent contribution (χd) were estimated by the following expression: χM = C/(T − Θ) + χd. Effective magnetic moment (μeff) was calculated using the following formula: μeff = (8·χM·T)1/2. H3Hhp was prepared according to ref 23. Anhydrous Dy3+(TMHD)3 (TMHD: 2,2,6,6-tetramethyl-3,5-heptanedionate) (>98%) was purchased from Strem Chemicals, Inc. (Shanghai, China) and decamethylcobaltocene (Cp*2Co) was purchased from Sigma-Aldrich (USA). o-Dichlorobenzene (C6H4Cl2; Acros Chemicals, Shanghai, China) was distilled over CaH2 under reduced pressure and n-hexane was distilled over Na/benzophenone. Solvents were degassed and stored in an MBraun 150B-G glove box (Germany). Salt 1 was synthesized and stored in the glove box with a controlled atmosphere containing less than 1 ppm of water and oxygen. KBr pellets used for IR and UV–vis–NIR analyses were prepared in the glove box. Magnetic measurements were performed on a polycrystalline sample of 1 sealed in a 2 mm quartz tube under ambient pressure under anaerobic conditions. Synthesis of 1 Crystals of (Cp*2Co){Dy3+(TMHD)2(Cl)(H2Hhp)}·2C6H4Cl2 ( 1) were obtained via the reaction of H3Hhp (14.2 mg, 0.021 mmol) with three equivalents of Dy3+(TMHD)3 (45 mg, 0.063 mmol) in the presence of one equivalent of Cp*2Co (7 mg, 0.021 mmol) in 16 mL of o-Dichlorobenzene (o-DCB) upon stirring at 50 °C for 24 h. The starting H3Hhp material was insoluble in C6H4Cl2; however, after 24 h, H3Hhp completely dissolved to give a red-brown solution. The solution obtained was cooled down to RT and filtered into a 1.8-cm-diameter 50 mL glass tube with a ground glass plug, and then 30 mL of n-hexane was layered over the solution. Slow mixing of the solutions over 1 month resulted in precipitation of the crystals. The solvent was then decanted from the crystals and washed with n-hexane. Black-brown plates of 1 were obtained in 54% yield. The composition of the obtained crystals was determined by X-ray diffraction analysis of a single crystal. Several crystals from one synthesis were found to consist of a single crystalline phase. The composition of the obtained crystals was determined from X-ray diffraction analysis on a single crystal. Several crystals from one synthesis were found to belong to a single crystalline phase. Elemental analysis supported the determined composition. Anal. Calcd. for C84H90Cl5CoDyN15O4S3, Mr = 1868.56: C, 54.00; H, 4.82; N, 11.24, Cl 9.50. Found: C, 53.74; H, 4.56; N, 11.02; Cl 9.92. X-ray crystal structure determination X-ray diffraction data for 1 at 110(2) K were collected on an Oxford diffraction "Gemini-R" CCD diffractometer (Oxford, UK) with graphite monochromated MoKα radiation using an Oxford Instrument Cryojet system. Raw data reduction to F2 was carried out using CrysAlisPro (Oxford Diffraction Ltd., UK).24 The structures were solved by direct method and refined by the full-matrix least-squares method against F2 using SHELX 2018/3.25 Nonhydrogen atoms were refined in the anisotropic approximation. Crystal data for 1 at 150.00(14) K: C84H90Cl5CoDyN15O4S3, F.W. 1868.56, dark black block, 0.565 × 0.132 × 0.068 mm, orthorhombic phase with space group P bcm, a = 10.4531(3), b = 30.2423(8), c = 28.5373(8) Å, α = β = γ = 90°, V = 9021.4(4) Å3, Z = 4, dcalcd = 1.376 M gm−3, μ = 1.279 mm−1, F(000) = 3828, 2θmax = 59.352°; 40331 reflections collected, 8110 independent; R1 = 0.0821 for 6009 observed data [>2σ(F)] with 364 restraints and 642 parameters; wR2 = 0.2212 (all data); final GoF = 1.105. CCDC 2264332. Crystal structure of 1 contained half of independent Cp*2Co+ cation and the {DyIII(TMHD−)2(Cl−)(H2Hhp−)}− anion. One tert-Bu group of DyIII(TMHD)2 was disordered between two orientations with 0.694(12)/0.306(12) occupancies. One of five CH3 groups of Cp*2Co+ is statistically disordered between two orientations. Also, there were two independent solvent C6H4Cl2 molecules which had only 0.5 occupancies. One molecule was statistically disordered between two orientations, whereas there were two orientations for the second molecule with 0.435(4)/0.065(4) occupancies. To keep the anisotropic thermal parameters of the disordered solvent atoms within reasonable limits, the displacement components were restrained using ISOR, SIMU, and DELU instructions from SHELXL program26 from the X-ray diffraction data. This resulted in the 364 restraints used for the refinement of crystal structures of 1. Computational details All reported structures were optimized at density functional theory (DFT) level using the Becke, 3-parameter, Lee–Yang–Parr (B3LYP)27 functional and the standard 6-31G(d,p) basis set for C, N, S, Cl, O and H. As much as 60-electron Stuttgart-Bonn relativistic pseudopotentials were used for Dy.28 The ultrafine integration grid was employed. No symmetry constraints were imposed. The calculations were performed considering a multiplicity of S = 6. Analytical harmonic frequencies were computed at the same level of theory to confirm the nature of the stationary points. All of the calculations were carried out by the methods implemented in the Gaussian 16 package.29 Time-dependent density functional theory (TD-DFT) calculations were carried out at the CAM-B3LYP30 level of theory using the basis set previously employed for optimization. Results and Discussion The synthetic approach towards the formation of Dy3+-H3Hhp complexes is depicted in Figure 2. As a Dy3+ source, we selected Dy3+(TMHD)3 due to (1) its stability and good solubility in organic solvents; (2) the labile coordination of TMHD to the metal, which facilitated the exchange with the chelate; and (3) the capability of TMHD ligand to deprotonate the macrocycle during the complexation, thereby releasing TMHD. Simultaneously, reducing conditions (i.e., decamethylcobaltocene: Cp2*Co+) were employed to ensure the solubility of the large and planar H3Hhp macrocycle. This strategy has been widely employed for the synthesis of crystalline porphyrinoid-based complexes with intriguing coordination environments.31–33 On this basis, H3Hhp was reacted with three equivalents of Dy3+(TMHD)3 and one equivalent of Cp2*Co+, in C6H4Cl2 at 50 °C. This process led to the complete solubilization of the macrocycle and the formation of a red-brown solution which, after mixing with n-hexane, afforded crystals in a 54% yield. Remarkably, elemental analysis on these crystals revealed a (Cp*2Co){Dy(TMHD)2(Cl)(H2Hhp−)}·3C6H4Cl2 composition, with H2Hhp− being H3Hhp but with one less hydrogen atom. Figure 2 | Synthesis of Dy-H3Hhp complex 1. Download figure Download PowerPoint To unambiguously elucidate the structure of the obtained compound, hereafter referred to as 1, their crystals were then analyzed by single-crystal X-ray diffraction. As shown in Figure 3a,b, 1 consisted of a Dy-H3Hhp complex, presenting off-centered coordination to a Dy atom through one isoindolic nitrogen and two nitrogen atoms of two different thiadiazol rings. Notably, this coordination mode was similar to that of previously observed on-surface. The Dy-H3Hhp complexes were surrounded by Cp*2Co+ molecules, and the nitrogen atoms of isoindole subunits not involved in the coordination remained protonated. Thus, the macrocyclic ligand is formally the deprotonated form of H3Hhp (H2Hhp−). The Dy atom, in turn, coordinated two TMHD ligands and, remarkably, a chlorine atom, which probably abstracted from the C6H4Cl2 used as the solvent. Similar abstraction processes have also been found in the synthesis of {Cryptand(Li+)}2{Li3Cl(Hhp)}2.32 In our case, the driving force seemed to be the strong tendency of the Dy atom to exhibit a coordination number of 8 or even higher, which, without chloride coordination would be 7. Analysis of the local symmetry of Dy3+ in 1 at 150 K using Shape34,35 indicated that the surrounding Dy3+ was rather far from any known polyhedral since all continuous shapes measures (CShM) values obtained by Shape are rather large (see Supporting Information Table S3). Infrared (IR) spectra of complex 1 and the starting components are given in Supporting Information Figure S1. The spectrum showed the presence of all components found in the complex. Bands of H3Hhp were shifted up to 12 cm−1 due to deprotonation and formation of the complex with Dy3+. Figure 3 | (a) X-ray structure and (b) crystal packing of 1. Atom color code of (a): carbon in gray, nitrogen in blue, hydrogen in white, oxygen in red, chlorine in purple, sulfur in pale yellow, and dysprosium in dark yellow. Orange and purple molecules in the packing correspond to Dy-H2Hhp and Cp*2Co fragments, respectively. Download figure Download PowerPoint Collectively, we inferred that 1 is based on a (Cp*2Co+){Dy3+(TMHD)2(Cl)(H2Hhp−)}− ion pair, where the negative charges of the ligands were compensated by Dy3+ and Cp*2Co+. This suggested that neither the macrocycle nor Dy3+ had been reduced. To get further structural insights into this off-centered Dy3+ complex, we went deeper into its structural analysis. Crystal structure of 1 contained half of independent Cp*2Co+ and {Dy3+(TMHD)2(Cl)(H2Hhp−)}− ions and one and a half independent C6H4Cl2 molecules. The geometry of the Dy3+ ions was square antiprismatic, although distorted due to the different lengths of the Dy-O (2.29–2.33 Å), Dy-Cl (2.410(3) Å) and Dy-N bonds with pyrrole and thiadiazole nitrogen atoms (2.489(3) and 2.561(3) Å, respectively). The Dy3+ center was positioned above the plane of three coordinated nitrogen atoms by 1.557 Å. As observed with Dy-Ps and Dy-Pcs complexes, this was ascribed to the large size of the Dy3+ ion, which prevented its insertion into the H2Hhp− cavity. On the other hand, the chloride atom was oriented toward the isoindolic N–H groups, presenting Cl-H distances within the range of H-bonding interactions. Regarding the macrocycle, this coordination mode induced a planarity deviation of the H2Hhp− core, leading to a bowl-like structure. It is important to highlight that the geometry of H2Hhp− anion is still unknown. However, as shown in Supporting Information Table S2, most bond lengths of 1 were similar to that of H3Hhp since the number of π-conjugated electrons does not change. Interestingly, in crystal packing, it is observed that Cp*2Co+ cations and {Dy3+(TMHD)2(Cl)(H2Hhp−)}− anion organize into an alternate fashion. This assembly was governed by π–π interactions between Cp* rings and the π-surface of Hhp opposite to the Dy3+ coordination. As both Cp*2Co+ and H2Hhp− groups were diamagnetic, magnetic coupling mediated by Cp*2Co+ is not expected. Then the optical properties of 1 were explored by UV/Vis spectroscopy. Comparison between spectra of 1, and that of H3Hhp are shown in Figure 4a. H2Hhp− displayed two intense bands located at 281 and 398 nm, and a shoulder at about 526 nm. Similarly, complex 1 exhibited two main bands at 298 and 398 nm, and a shoulder at about 552 nm. This result was in line with the fact that the deprotonation took place without reduction. The lack of new bands further supported that the macrocycle was not reduced, as it would result in the lowest unoccupied molecular orbital (LUMO) population and the appearance of new transitions from LUMO to higher-energy orbitals. The very weak and broad band located at 1100 nm was attributed to charge transfer stemming from the π–π interaction between {Dy3+(TMHD)2(Cl)(H2Hhp)}− and Cp*2Co+ ions. As observed by TD-DFT calculations (see Supporting Information for further details), the observed bands were mainly derived from transitions between six orbitals, three occupied, and three unoccupied, which were located in the macrocycle. Figure 4 | (a) Spectra of the starting H3Hhp material and complex 1 in the UV–vis–NIR range in KBr pellets. Pellet 1 was prepared in anaerobic conditions. (b) DFT calculated molecular orbitals of 1 involved in the transitions observed in the absorption spectrum. 233, 236, and 244 are occupied orbitals, whereas 245, 248, and 250 are virtual orbitals. NIR, near-infrared; DFT, density functional theory. Download figure Download PowerPoint Remarkably, despite using three equivalents of Dy3+(TMHD)3, the final compound only incorporated one Dy atom. This was surprising, considering that the H2Hhp− still presented coordination sites to accommodate at least one further Dy atom. To shed light on the origin of this intriguing finding, we performed DFT theoretical calculations (see Supporting Information for further details). Specifically, the theoretical structures of complexes coordinating two Dy atoms were fully optimized, and the corresponding complexation energies were calculated. Since this fragment was expected to have a negligible influence on the complexation selectivity, the cation Cp2*Co was excluded from the model to save computational costs. For the optimization of these binuclear complexes, two coordination systems were proposed: Dy2Cl2, wherein both Dy atoms presented a coordination number of 8 and were connected through two chloride bridges; Dy2Cl, wherein the Dy atoms are linked through just one chloride bridge, thereby one Dy atom presented a coordination number of 7, while the other was 8. The resulting structures and their relative complexation energies are illustrated in Figure 5. Interestingly, the first Dy complexation (i.e., from H3Hhp to 1) was found to be exergonic, while the second one was determined to be energetically unfavorable, regardless of whether the product formed was Dy2Cl2 or Dy2Cl. As noticed in Figure 5, the macrocyclic skeleton in 1, while less planar than free base H3Hhp, still allowed for efficient π-conjugation between the different units. Conversely, Dy2Cl2 and Dy2Cl exhibited a core largely deviated from planarity, wherein the antiprismatic structure of Dy displayed a pronounced distortion. Based on this, we hypothesized that the coordination of a second Dy atom did not occur, as it would have significantly disrupted the π-conjugation within the macrocycle and caused destabilization of the Dy coordination complex. Figure 5 | DFT calculated the energy profile and molecular structures of the successive complexation of Dy3+ atoms to the H3Hhp macrocycle. Atom color code of (a): carbon in green, nitrogen in blue, hydrogen in white, oxygen in red, chlorine in purple, sulfur in pale yellow, and dysprosium in dark yellow. DFT, density functional theory. Download figure Download PowerPoint Given the potential magnetic behavior of 1, its magnetic properties were preliminarily studied as a polycrystalline sample sealed under argon in the quarts tube. In the EPR spectra, no signals attributable to Dy3+ were detected, likely due to the significant zero-field splitting for Dy3+, which is typically much greater than the energy of a microwave quantum at the X-band frequency. Instead, only a weak and narrow EPR signal was observed ( Supporting Information Figures S4 and S5), whose integral intensity corresponded to the contribution of 2.6% of S = 1/2 spins per formula unit, indicating that it originated from impurities. The signal had a g value of 2.0042 and a linewidth (ΔH) of 0.87 mT at 235 K and split into two lines below 100 K. At 4.5 K, the parameters of the components were g1 = 2.0054, ΔH = 1.47 mT, and g2 = 2.0035, ΔH = 0.87 mT. Based on these parameters, it could be concluded that anionic impurities were predominantly localized on the Hhp ligand. Dy3+ ion has the 6H15/2 electron configuration at g = 4/3.36 An effective magnetic moment of 1 was found to be 10.35 μB at 300 K, similar to the theoretically calculated magnetic moment for isolated Dy3+ ion (10.65 μB).34,35 The magnetic moment of 1 was nearly temperature-independent (Figure 6a). Temperature dependency of reciprocal molar magnetic susceptibility was linear, which allowed for the determination of a Weiss temperature of −3 K ( Supporting Information Figure S3). This value indicated only weak antiferromagnetic coupling of spins in 1. As previously mentioned, the paramagnetic Dy3+ ions were completely isolated by diamagnetic components. As a result, the shortest distance between the paramagnetic centers was 10.45 Å, which enabled only weak magnetic coupling of spins. The magnetization was saturated even at 1 T magnetic field reaching the value of 8.26 μBNA (Figure 6b). This value was nearly independently preserved up to 5T. Hysteresis was not observed in 1 at 2 K under 20 Oe/s of the magnetic field. On the other hand, dynamic properties studied at zero magnetic fields showed that 1 was not a single ion magnet since no peaks were observed in the temperature dependency studies of in-phase (χ′) and out-of-phase (χ″) signals at 2–1500 Hz. We ascribed this lack of magnetic behavior to the strongly distorted antiprismatic geometry of Dy3+. Indeed, geometric shape analysis34,35 showed that the environment of Dy3+ was rather far from square antiprism ( Supporting Information Table S3). Figure 6 | (a) Temperature dependence of the effective magnetic moment of polycrystalline 1 measured in the 1.9–300 K range; (b) Dependence of magnetization versus magnetic field up to 50 kOe (black line is a guide to the eye) for polycrystalline 1. Download figure Download PowerPoint Conclusions In this work, we have demonstrated that H3Hhp is a promising ligand for fabricating magnetically active Dy3+ complexes. In this regard, we found that performing complexation under reductive conditions is a powerful strategy to control the selectivity without altering the oxidation state of the expanded porphyrin. As observed by X-ray diffraction analysis, the H3Hhp macrocycle was found to selectively bind one Dy3+ atom, despite using an excess of the Dy3+ source. DFT calculations suggested that the coordination of an additional Dy3+ atom would destabilize the macrocycle structurally and electronically. The resulting mononuclear complex 1, was found to exhibit an off-centered, out-of-plane coordination, as well as a directional supramolecular organization directed by π–π interactions with Cp*2Co molecules. This organization avoided the magnetic coupling between the Dy3+ centers. Importantly, the electronic properties of the H3Hhp macrocycle remained mostly intact after complexation. Overall, this work provides key insights into the coordination of magnetically active metals with expanded porphyrinoids, which will motivate the development of novel SMMs. Current efforts toward more complex systems with different geometries and coordination modes are ongoing in our laboratories. Supporting Information Supporting Information is available and includes general information, IR results, additional magnetic measurements, X-ray data, computational details, and molecular coordinates. Conflict of Interest There is no conflict of interest to report. Acknowledgments D.V.K. acknowledges financial support from the Russian Science Foundation (project N 21-13-00221) for the synthesis and studies of optical and magnetic properties of 1. The analysis of the IR spectra was supported by the Ministry of Science and Higher Education of the Russian Federation (Registration number 124013100858-3), E.N.I. and M.K.I. acknowledge Grant from the Ministry of Science and Higher Education of the Russian Federation (no. 075-15-2021-579) for synthesis of H3Hhp and preliminary DFT calculations. T.T. acknowledges financial support from the Spanish MCIN/AEI/10.13039/501100011033 (PID2020-116490GB-I00, TED2021-131255B-C43), the Comunidad de Madrid, and the Spanish State through the Recovery, Transformation and Resilience Plan ["Materiales Disruptivos Bidimensionales (2D)" (MAD2D-CM) (UAM1)-MRR Materiales Avanzados], and the European Union through the Next Generation EU funds. Instituto madrileño de estudios avanzados Nanociencia acknowledges support from the "Severo Ochoa" Programme for Centres of Excellence in R&D (Ministerio de asuntos economicos y transformacion digital, Grant SEV2016-0686). T.T. also acknowledges the Alexander von