Synthesis, X-ray Crystallography, Spectroscopic Characterizations, Density Functional Theory, and Hirshfeld Surface Analyses of a Novel (Carbonato) Picket Fence Iron(III) Complex

An Fe(III)-carbonato six-coordinate picket fence porphyrin complex with the formula [K(2,2,2-crypt)][FeIII(TpivPP)(CO3)]·C6H5Cl·3H2O (I) has been synthesized and characterized by UV-Vis and FT-IR spectra. The structure of (carbonato)(α,α,α,α-tetrakis(o-pivalamidophenyl)porphinato)ferrate(III) was also established by XRD. The iron atom is hexa-coordinated by the four nitrogen atoms of the pyrrol rings and the two oxygen atoms of the CO32− group. Complex I, characterized as a ferric high-spin complex (S = 5/2), presented higher Fe-Np (2.105(6) Å) and Fe-PC (0.654(2) Å) distances. Both X-ray molecular structure and Hirshfeld surface analysis results show that the crystal packing of I is made by C-H⋯O and C-H⋯Cg weak intermolecular hydrogen interactions involving neighboring [FeIII(TpivPP)(CO3)]− ion complexes. Computational studies were carried out at DFT/B3LYP-D3/LanL2DZ to investigate the HOMO and LUMO molecular frontier orbitals and the reactivity within the studied compound. The stability of compound I was investigated by analyzing both intra- and inter-molecular interactions using the 2D and 3DHirshfeld surface (HS) analyses. Additionally, the frontier molecular orbital (FMO) calculations and the molecular electronic potential (MEP) analyses were conducted to determine the electron localizations, electrophilic, and nucleophilic regions, as well as charge transfer (ECT) within the studied system.


Introduction
Metalloporphyrins can appear as powerful materials for the active sites of a certain number of enzymes, such as hemoproteins (hemoglobins, myoglobins, etc.) [1][2][3][4].In the case of hemoglobin, the heme and the protein are linked together by the coordination of residues of the protein chain on the axial coordination site of iron.In general, Fe(III) can be divided into four different electronic ground states: high-spin (S = 5/2), intermediatespin (S = 3/2), admixed-spin (S = 5/2, 3/2), and low-spin (S = 1/2).All these situations closely resemble the properties of iron (III) hemoproteins and make iron (III) porphyrins a good model for studying and understanding several properties of biomolecules.It is noteworthy that investigations on iron (III) porphyrins with bidentate axial ligands are quite rare in the literature; for example, the carbonate is not toxic to the environment.The results obtained from the structural and spectroscopic investigation of the picket fence derivative give some idea of the relative importance of the bidentate ligand vis-à-vis the stereochemical and electronic properties of the iron(III) high-spin porphyrin species.These results provide more insight into the geometry and the electronic structure of the high-spin iron(III) porphyrin derivatives with bidentate oxyanionic ligands.
Increased equatorial Fe-Np distance results in a higher spin state of the iron(III) porphyrins.This increase in distance leads to a significant decrease in the interaction between the iron d x 2 −y 2 and porphyrin a 2u orbitals [5].In general, hex-coordinated Fe(III) porphyrinates with anionic ligands can be observed in two different electronic configurations: high-spin (S = 5/2) or low-spin (S = 1/2) [6].The five 3d orbitals of iron(III) separate into two energy groups: those of higher energy (d x 2 −y 2 and d z 2 ) and those of lower energy (d xy , d xz and d yz ).This separation highlights the electronic spin state of the iron atom in the triflate complex, but in the [K(2,2,2-crypt)][Fe III (TpivPP)(CO 3 )] complex, the spin is strong (S = 5/2).
Complex I was characterized by both spectroscopic UV/Vis and FT-IR.The molecular structure of this new hexacoordinated iron(III) metalloporphyrin was determined by single crystal X-ray diffraction (XRD).The Hirshfeld surface examination and DFT calculations of compound I confirm the high-spinstate.Our study focused on the picket fence porphyrin due to its ability to stabilize ionic ligands bonded to the iron atom, making it a suitable choice for our investigation [7].

Experimental 2.1.1. Materials and Methods
All other solvents and reagents are used in specific cases, either to dissolve complexes or to facilitate obtaining the synthesized products.Depending on their uses, they must be treated and distilled in some cases, while in other cases, they are used commercially without any treatment.
UV/Vis spectral data for the complex were collected using WinASPECT PLUS (SPECORD PLUS version 4.2).The FT-IR spectra were carried out in the solid state on a Perkin-Elmer model 398 instrument, ranging from 4000 to 400 cm −1 .The crystals obtained after the diffusion of pentane in chlorobenzene were ground with dry KBr to form pellets (1-2 mg of the sample per 100 mg of KBr).
Single crystal XRD data were collected by a Bruker-Nonius FR590 Kappa CCD diffractometer.Hirshfeld surface (HS) analysis is usually performed using Crystal Explorer 3.15 [8,9].This program generates HS and 2D fingerprint plots of a given compound using its crystallographic information file, or CIF.The "d norm " Hirshfeld surface is obtained by the combination of the normalized distances from the closer atom inside the surface "d i " and the outside of the surface "d e " to the HS surface, showing all the intermolecular contacts of the crystal structure [10,11].(4,7,13,16,21,24-hexaoxa-l,l0-diazabicyclo[8.8.8]hexacosane (86.59 mg, 0.23 mmol) and potassium carbonate K 2 CO 3 (55.28mg, 0.40 mmol) were mixed together for 1 h in the chlorobenzene (V = 10 mL).[Fe III (TpivPP)Cl] [12] (25 mg, 0.023 mmol) in the C 6 H 5 Cl (V = 5 mL) was added to the carbonato/cryptand-222 and stirred for 3 h.The hex-coordinate (carbonato)iron(III) porphyrin complex was precipitated by the addition of dry pentane.

X-ray Crystallography
The crystals of the carbonato iron (III) are obtained by slow diffusion in test tubes.These crystals are washed and rinsed with pentane, then dried and well visualized on the electronic microscope while eliminating impurities.Single crystal mounted on the goniometric head using a Bruker-AXS APEX2 2014 [13].Data were collected at room temperature using the radiation Kα of Mo (λ Mo = 0.7107 Å).Complex I crystallizes in the monoclinic system (P2 1 /n) with four formulas per cell (Z = 4).
The X-ray diffractionstructure was resolved using the direct method SIR-2004-1.0 [14] and refined against F 2 using the SHELXL-97 package [15].During the refinement of the structure complex I, four disorder problems were encountered: (a) the tert-butyl group of one picket is disordered over two orientations C29A-C30A-C31A/C29B-C30B-C31B, with a major position occupancy of 0.512 (7); (b) the one O atom of the TpivPP is occupying/disordered over two orientations O1A/O1B with a major position occupancy of 0.529 (1); and (c) the two oxygen atoms of the CO 3 2− group are disordered in two positions (O5A-O6A/O5B-O6B) with a major position occupancy of 0.548 (1).
The anisotropic displacement ellipsoids of complex I were very extended, which indicates a static disorder.For fragments involving these atoms, the ISOR/SIMU restraints [16] are used, which explains the huge number of restraints.All hydrogen atoms were placed using assumed geometry, with C-H aromatic = 0.95 Å and C-H methyl = 0.98 Å.The displacement parameters of the H atoms were set to 1.2 (1.5 for methyl).The geometrical calculations were carried out using the program PLATON (Spek, 2002) [17].The molecular drawings were made using ORTEP3 for Windows [18], and the packing diagrams were generated using the software MERCURY 4.0 [19].
To model the structure of compound I, we omitted the disordered chlorobenzene and aqua solvent molecules using the PLATON software [20].It is obtained from our solvent-accessible voids with a volume of 4 × 229.25 Å 3 , and the number of electrons per unit cell generated by squeeze was 4 × 22 e.The corresponding results for our compound are given in Table 1.

Synthesis of Complex I
The synthesis of picket fence porphyrin was made according to the reported method [12].The formula of this species is 4α-H 2 TpivPP, but it is usually written as H 2 TpivPP.Scheme S1 illustrates the different steps leading to the preparation of this meso-arylporphyrin, which is known to protect iron (II) porphyrins with small axial ligands that are unstable using "nonprotected" porphyrin such as H 2 TPP (meso-tetraphenylporphyrin) or H 2 OEP (octaethylporphyrin).This is the case of the [Fe II (TpivPP)(l-MeIm)O 2 ] [12] (1-MeIm = 1-methylimidazole) complex, where the oxo group is located inside the pocket of the TpivPPporphyrinate, leading to the stability of this species.
Scheme 2. Two-dimensional chemical graph of complex I.

Spectroscopic Characterizations
The UV-visible spectra of H2TpivlPP, [Fe III (TpivPP)Cl], and complex I are illustrated in Figure 1.Table S1 compares the λmax values with those of other meso-porphyrin-iron metalloporphyrin compounds.
The concentration used for the spectrum in the Soret band region is 1.5 × 10 −6 M, while the concentration used in the Q band area is 6.1 × 10 −5 M.This spectrum presents a Soret band around 424 nm and a β and α bands around 576 nm and 607 nm, respectively.
These results are similar for iron(III) meso-porphyrin complexes with anionic axial ligands [21].
Scheme 2. Two-dimensional chemical graph of complex I.

Spectroscopic Characterizations
The UV-visible spectra of H 2 TpivlPP, [Fe III (TpivPP)Cl], and complex I are illustrated in Figure 1.Table S1 compares the λ max values with those of other meso-porphyrin-iron metalloporphyrin compounds.The optical gap (Eg-opt) value of complex I was determined using the tangent method according to the formula: where λLim is the intersection between the tangent to the highest Q band and the horizontal (Figure S1).This experimental value is 1.907 eV, which is common for porphyrins and metalloporphyrins and indicates the semi-conductor character of our carbonato iron(III) complex.
Complex I shows an intensive absorption peak in the infrared spectrum located at 1104 cm -1 ,which corresponds to the -CH2-O-CH2-group of [K(crypt-222)] + (see Figure 2).It exhibits typical absorption bands of H2TpivPP with the ν(C=O) of the carbonyl group of the pivaloyl and δ(CCH) bending frequencies at 1680 cm −1 and 988 cm −1 , respectively.In the same IR spectrum of complex I, two weak bands at 1636 and 1356 cm −1 attributed to the ν1(C-O) and ν2(C-O) vibrations confirm the existence of the (CO3) 2− ligand.The concentration used for the spectrum in the Soret band region is 1.5 × 10 −6 M, while the concentration used in the Q band area is 6.1 × 10 −5 M.This spectrum presents a Soret band around 424 nm and a β and α bands around 576 nm and 607 nm, respectively.
These results are similar for iron(III) meso-porphyrin complexes with anionic axial ligands [21].
The optical gap (E g-opt ) value of complex I was determined using the tangent method according to the formula: E g-opt = 1239.8/λLim where λ Lim is the intersection between the tangent to the highest Q band and the horizontal (Figure S1).This experimental value is 1.907 eV, which is common for porphyrins and metalloporphyrins and indicates the semi-conductor character of our carbonato iron(III) complex.
Complex I shows an intensive absorption peak in the infrared spectrum located at 1104 cm −1 , which corresponds to the -CH 2 -O-CH 2 -group of [K(crypt-222)] + (see Figure 2).It exhibits typical absorption bands of H 2 TpivPP with the ν(C=O) of the carbonyl group of the pivaloyl and δ(CCH) bending frequencies at 1680 cm −1 and 988 cm −1 , respectively.In the same IR spectrum of complex I, two weak bands at 1636 and 1356 cm −1 attributed to the ν 1 (C-O) and ν 2 (C-O) vibrations confirm the existence of the (CO 3 ) 2− ligand.
The geometric parameters Fe-Np, Fe-XL, and Fe-PCin compound I and a selection of some other six-coordinate iron(III) high-spin (S = 5/2) and low-spin (S = 1/2) porphyrin complexes are given in Table 3.The asymmetric unit of (I) contains the anioncomplex [Fe III (TpivPP)(CO 3 )] − with one [K(2,2,2-crypt)] + cation, one C 6 H 5 Cl solvent, and three molecules of water.A disordered chlorobenzene and three molecules of water, which could not be modeled, were removed from the lattice of I by using the squeeze procedure [20].The ortep diagram shows the structure of the anioncomplex (see Figure 3).The geometric parameters (bond length (Å) and angles ( • )) of complex I are reported in Table 2.The [K(crypt-222)] + counterion is shown in Figure S2.The K-O (crypt-222) and K-N (crypt-222) distances [2.818 (6) Å and 3.039 (6) Å, respectively] are in agreement with the literature values [21].
The geometric parameters Fe-Np, Fe-X L , and Fe-P C in compound I and a selection of some other six-coordinate iron(III) high-spin (S = 5/2) and low-spin (S = 1/2) porphyrin complexes are given in Table 3.In complex I, Fe-Np (2.105(6) Å) and Fe-P C (0.654(2) Å) distances are in the normal range of 2.048-2.125Å and 0.20-0.75Å, respectively.This value confirms clearly that compound I is a hexacoordinated metalloporphyrin with highspin (S = 5/2).However, sixcoordinate iron (III) low-spin porphyrin species present lower Fe-P C and Fe-Np distances.Figure 4 illustrates the crystal packing of complex I perpendicular to the a axis.In order to investigate the intermolecular interactions within the crystal packing of complex I, we used the PLATON program [17], as described just above, to obtain a good visualization of these intermolecular interactions (see Figures 5 and 6).In order to investigate the intermolecular interactions within the crystal packing of complex I, we used the PLATON program [17], as described just above, to obtain a good visualization of these intermolecular interactions (see Figures 5 and 6).
Figure 7 represents the coordination polyhedral and the environment of iron.The distances between the two O atoms O5A/O6A of the CO 3 2− and the iron atom are 2.047(15) Å and 2.00(2) Å, respectively.The two values of bond length are almost equal and are slightly shorter than the third distance Fe-O7 (CO 3 2− ) bond length.The long bond length observed in our case is probably due to the type and environment of the porphyrin used.
The porphyrin core is shown in Figure 8.The Fe-porphyrin and the number of coordinations for iron have several properties for the irregular and non-planar conformation of the porphyrin core.The diagram highlights significant saddling and moderate doming distortions of the macrocycle [27].The porphyrin core is shown in Figure 8.The Fe-porphyrin and the number of coordinations for iron have several properties for the irregular and non-planar conformation of the porphyrin core.The diagram highlights significant saddling and moderate doming distortions of the [27].

Computational Details
The DFT calculations were made based on the crystallographic CIF (Crystallographic Information File) using the DFT/B3LYP-D3/LanL2DZ [28][29][30] level of theory, as implemented in Gaussian 09 [31].The represented figures have been selected using Gauss View 5 [32].Analysis of HOMO and LUMO orbital occupancies gives insights into the electron  The porphyrin core is shown in Figure 8.The Fe-porphyrin and the number of coordinations for iron have several properties for the irregular and non-planar conformation of the porphyrin core.The diagram highlights significant saddling and moderate doming distortions of the macrocycle [27].

Computational Details
The DFT calculations were made based on the crystallographic CIF (Crystallographic Information File) using the DFT/B3LYP-D3/LanL2DZ [28][29][30] level of theory, as implemented in Gaussian 09 [31].The represented figures have been selected using Gauss View 5 [32].Analysis of HOMO and LUMO orbital occupancies gives insights into the electron

DFT-D3 Investigations of Compound I 3.1. Computational Details
The DFT calculations were made based on the crystallographic CIF (Crystallographic Information File) using the DFT/B3LYP-D3/LanL2DZ [28][29][30] level of theory, as implemented in Gaussian 09 [31].The represented figures have been selected using Gauss View 5 [32].Analysis of HOMO and LUMO orbital occupancies gives insights into the electron localization on the surface of the material and the charge transfer mechanisms within the complex [33].The molecular electrostatic potential (MEP) was determined to investigate the electrophilic and nucleophilic sites on the compound's surface.The Hirshfeld surface (HS) analyses were deeply studied to elucidate the responsible inter-and intra-molecular interactions that contribute to the stability of the compound.

Optimized Structure of [K(crypt-222)][Fe III (TpivPP)(CO 3 )] (I)
Figure 9 depicts a side view of our studied compound.Table 4 presents a compilation of selected experimental and calculated bond lengths and angles within the coordination sphere polyhedral surrounding the iron(III) central ion of complex I.The comparison between experimental and theoretical values for this dihaptocarbonato iron(III) complex reveals a high degree of proximity.Specifically, the Fe-Np distances are measured at 2.105 (6) Å experimentally and 2.052 Å theoretically, while the Fe-O(axial ligand) distances are recorded at 2.00(2)/2.047(2)experimentally and 1.992/2.001Å theoretically.This difference between the experimental and theoretical distance values may be due to the fact that the calculated values are obtained assuming a gas phase, while the experimental values were obtained from the X-ray crystal structure (solid state).

Optimized Structure of [K(crypt-222)][Fe III (TpivPP)(CO3)] (I)
Figure 9 depicts a side view of our studied compound.Table 4 presents a compilation of selected experimental and calculated bond lengths and angles within the coordination sphere polyhedral surrounding the iron(III) central ion of complex I.The comparison between experimental and theoretical values for this dihaptocarbonato iron(III) complex reveals a high degree of proximity.Specifically, the Fe-Np distances are measured at 2.105 (6) Å experimentally and 2.052 Å theoretically, while the Fe-O(axial ligand) distances are recorded at 2.00(2)/2.047(2)Å experimentally and 1.992/2.001Å theoretically.This difference between the experimental and theoretical distance values may be due to the fact that the calculated values are obtained assuming a gas phase, while the experimental values were obtained from the X-ray crystal structure (solid state).
Additionally, the Fe-O5A-C65 angle is determined to be approximately 93.26°, closely aligning with the experimental value of 95.50°.It is observed that the H … H interaction is low bonding, formed between the [K(crypt-222)] and the compound.These findings support the notion of strong agreement between theoretical predictions and experimental observations, underscoring the robust stability and effective group interactions within complex I.   Additionally, the Fe-O5A-C65 angle is determined to be approximately 93.26 • , closely aligning with the experimental value of 95.50 • .It is observed that the H• • • H interaction is low bonding, formed between the [K(crypt-222)] and the compound.These findings support the notion of strong agreement between theoretical predictions and experimental observations, underscoring the robust stability and effective group interactions within complex I.

HOMO/LUMO and Global Reactivity Investigations
The HOMO and LUMO iso-surfaces are key parameters for determining electron acceptance or donation ability in the compound [34][35][36][37].Molecular orbitals (FMO) provide a clear idea of the electron occupations in the studied material and electronic charge transfer (ECT), aiding in the understanding of the electronic properties of materials [38].Furthermore, the gap energy gives a clear idea concerning the chemical reactivity, kinetic stability, global hardness-softness characteristics, and optical polarizability of the compound.Moreover, the FMO analysis offers insights into the acceptor regions, which is beneficial for biological applications.The HOMO and LUMO orbitals are shown in Figure 10.Analysis of the HOMO orbital reveals an electron accumulation around the central metal Fe and the anionic axial ligand.Subsequently, these lone pairs of electrons cross the forbidden band to the LUMO orbitals, where they are accumulating along the ligand.This discovery suggests a significant charge transfer occurring between the Fering and the neighboring ligand.The localization of high electron populations on the surface is necessary for biological mechanisms.The ε HOMO ε LUMO energies were found to be −5.82eV and −2.50 eV, respectively.The gap energy was found to be 1.87 eV.This indicates the chemical and kinetic stability of our material, as well as its polarizability properties.Additionally, global reactivity parameters were calculated using Koopman's theorem, with the results presented in Table 5.
A low global hardness value of approximately 0.93 eV was obtained, and it can be concluded that electrons can easily cross from S0 (ground state) to S1 (excited state).The chemical potential (µ) and hardness (η) values are around −3.90 eV and 0.93 eV, as shown in Table 5, suggesting the stability of the compound, a result supported by molecular electrostatic potential (MEP) and FMO analysis.The significant electronegativity (χ = 3.90 eV) indicates its potential for electronic charge transfer with the target receptor.Furthermore, the high electrophilicity index (ω) of 8.17 eV suggests a highly inhibitory system.
A low global hardness value of approximately 0.93 eV was obtained, and it can be concluded that electrons can easily cross from S0 (ground state) to S1 (excited state).The chemical potential (µ) and hardness (η) values are around −3.90 eV and 0.93 eV, as shown in Table 5, suggesting the stability of the compound, a result supported by molecular electrostatic potential (MEP) and FMO analysis.The significant electronegativity (χ = 3.90 eV) indicates its potential for electronic charge transfer with the target receptor.Furthermore, the high electrophilicity index (ω) of 8.17 eV suggests a highly inhibitory system.The molecular electrostatic potential (MEP) is a technique that is suitable for determining and understanding the electrophilic (negative potential) and nucleophilic (positive potential) sites that characterize our compound.MEP is an important tool for identifying acceptor and donor attack sites that are useful for sensor and biological applications.

Molecular Electrostatic Potential (MEP) Analysis
The MEP is represented by color codes identifying the sign of potential in each region, ranging from red to blue.The 3D MEP plot is shown in Figure 11.It can be seen that a dark red color (indicating positive electrostatic potential) surrounds the dihaptocarbonato near the central metal Fe, suggesting a high electronic localization in this area.Additionally, the clear presence of a positive electrostatic potential (blue region) around the iron and neighboring groups indicates the electrophilic nature of this area.This finding concluded that a highly electronic/energy charge transfer takes place on the surface of the studied compound, as confirmed by FMO analyses.The identification of the existence of double electrophilic and nucleophilic sites resulted in the exceptional ability of [K(2,2,2-crypt)][Fe III (TpivPP)(CO 3 )] to function as both electron donors and acceptors.This highlights the high capacity of this material for potential applications in sensors and biological applications.
tive potential) sites that characterize our compound.MEP is an important tool for identifying acceptor and donor attack sites that are useful for sensor and biological applications.
The MEP is represented by color codes identifying the sign of potential in each region, ranging from red to blue.The 3D MEP plot is shown in Figure 11.It can be seen that a dark red color (indicating positive electrostatic potential) surrounds the dihaptocarbonato near the central metal Fe, suggesting a high electronic localization in this area.Additionally, the clear presence of a positive electrostatic potential (blue region) around the iron and neighboring groups indicates the electrophilic nature of this area.This finding concluded that a highly electronic/energy charge transfer takes place on the surface of the studied compound, as confirmed by FMO analyses.The identification of the existence of double electrophilic and nucleophilic sites resulted in the exceptional ability of [K(2,2,2crypt)][Fe III (TpivPP)(CO3)] to function as both electron donors and acceptors.This highlights the high capacity of this material for potential applications in sensors and biological applications.

Hirshfeld Surface (HS) Analysis
Hirshfeld surface (HS) and two-dimensional (2D) fingerprint plots are robust analytical tools that provide a comprehensive insight into intra-and intermolecular interactions within the crystal lattice [39,40].The HS serves as a valuable resource for comprehending the co-existing forces between constituent groups within the crystal structure, which ultimately dictate the stability of the molecular complex [41].The 2Dfingerprint plot is generated as a de in the function of di, representing the percentage of atomic contacts.The HS iso-surfaces offer a visual representation of interaction through a color-coded scheme, with red, white, and blue spots denoting varying degrees of interaction intensity.Dark red regions signify strong hydrogen bonding interactions; white regions indicate proximity in van der Waals contacts; and blue regions represent longer-range interactions.The dnormis located between −0.4481 Å and −0.8821 Å, the shape index is −1 to 1 Å, and the curvedness varies from −4 to 0.4 Å.The normalized distance dnorm is calculated using the following formula [42,43]: The dnorm is intricately linked to both de and di, where the parameters r and r delineate the van der Waals radii of the atom.The dnorm, de, curvedness, fragment path, and 2Dfingerprint plot have been illustrated in Figure 12a

Hirshfeld Surface (HS) Analysis
Hirshfeld surface (HS) and two-dimensional (2D) fingerprint plots are robust analytical tools that provide a comprehensive insight into intra-and intermolecular interactions within the crystal lattice [39,40].The HS serves as a valuable resource for comprehending the co-existing forces between constituent groups within the crystal structure, which ultimately dictate the stability of the molecular complex

21 Figure 2 .
Figure 2. Experimental IR spectrum of complex I.

Figure 2 .
Figure 2. Experimental IR spectrum of complex I.

21 Figure 3 .
Figure 3. Ortep diagram showing the [Fe III (TpivPP)(CO3)] − ion complex.Thermal ellipsoids are drawn at the 30% probability level.Only the major positions of the disordered fragments are shown, and the hydrogen atoms have been omitted for clarity.

Figure 3 .
Figure 3. Ortep diagram showing the [Fe III (TpivPP)(CO 3 )] − ion complex.Thermal ellipsoids are drawn at the 30% probability level.Only the major positions of the disordered fragments are shown, and the hydrogen atoms have been omitted for clarity.

Molecules 2024 , 21 Figure 4 .
Figure 4. Projection of the packing diagram of complex I down the a axis.Only the major positions of the disordered fragments are shown, and the hydrogen atoms have been omitted for clarity.

Figure 4 .
Figure 4. Projection of the packing diagram of complex I down the a axis.Only the major positions of the disordered fragments are shown, and the hydrogen atoms have been omitted for clarity.

Figure 5 .
Figure 5. Drawing illustrating the C-H … O intermolecular interactions in complex I.

Figure 7
Figure 7 represents the coordination polyhedral and the environment of iron.The distances between the two O atoms O5A/O6A of the CO3 2− and the iron atom are 2.047(15) Å and 2.00(2) Å, respectively.The two values of bond length are almost equal and are slightly shorter than the third distance Fe-O7 (CO3 2− ) bond length.The long bond length observed in our case is probably due to the type and environment of the porphyrin used.

Figure 7
Figure 7 represents the coordination polyhedral and the environment of iron.The distances between the two O atoms O5A/O6A of the CO3 2− and the iron atom are 2.047(15) Å and 2.00(2) Å, respectively.The two values of bond length are almost equal and are slightly shorter than the third distance Fe-O7 (CO3 2− ) bond length.The long bond length observed in our case is probably due to the type and environment of the porphyrin used.

Figure 9 .
Figure 9. Optimized structure of studied compound I.Figure 9. Optimized structure of studied compound I.

Figure 9 .
Figure 9. Optimized structure of studied compound I.Figure 9. Optimized structure of studied compound I.

Figure 11 .
Figure 11.MEP plot of studied compound I.
,b.The percentages of contacts have been graphically represented in a 2D diagram, as depicted in Figure 12c.H ... H interactions dominate the Hirshfeld surface, accounting for 77.4% of the total surface area.The

Figure 11 .
Figure 11.MEP plot of studied compound I.