*3.1.3 Ba(THPEN)(PIC)2 (3)*

Ba(II) is ten-coordinate in its monomeric complex (**3**) (**Figure 3**). The ligand THPEN coordinates through both its nitrogen atoms and all the four hydroxyl oxygen. The two picrate ions are also directly coordinated to Ba2+ ion through the phenolic oxygen and one oxygen of the o-nitro group. Since both the picrates are directly interacting with the cation, the complex is termed as tight ion-paired complex as is found in the crystallographically determined complex. The observed and calculated positions of barium and donor atoms are in agreement. There is negligible deviation found in bond length, bond angle (0.11°) and torsion angle of ligand THPEN for calculated title complex (**3**) and experimental Ba(THPEN)(PIC)2

and one of the o-nitro oxygen. The observed and calculated positions of calcium and donor atoms are in agreement. A comparison of bond lengths and bond angles provided a maximum tolerance of 0.27 Å and 16.33°Å, respectively (**Table 1** and **Table S1**; **Figure S1a,b**) of computed title complex (**1**) and crystallographically determined complex [Ca(THEEN)(PIC)](PIC). The torsion angles of the ligand THEEN in theoretically determined and experimental complex are also in well

*Comparison of experimental and calculated and torsion angles (°) of ligand in the complexes (4–6).*

**Name of the Complex (1) Complex (2) Complex (3) Atoms Theo. Exp. Dev. Theo. Exp. Dev. Theo. Exp. Dev.** O1-C1-C2-N1 55.1 55.05 0.05 57.9 58.0 0.1 32.3 32.4 0.1 C1-C2-N1-C5 165.1 165.1 0.0 82.8 82.7 0.1 161.9 162.0 0.1 C2-N1-C5-C6 159.0 159.0 0.0 165.5 165.5 0.0 157.6 157.8 0.2 N1-C5-C6-N2 65.4 65.3 0.1 60.4 60.5 0.1 65.9 66.1 0.2 C5-C6-N2-C8 159.1 159.0 0.1 159.3 159.4 0.1 C6-N2-C8-C7 89.1 89.1 0.0 163.6 163.7 0.1 N2-C8-C7-O3 60.9 60.9 0.0 34.1 34.2 0.1 O2-C3-C4-N1 36.5 36.7 0.2 55.5 55.6 0.1 46.8 46.9 0.1 C3-C4-N1-C5 121.6 121.7 0.1 161.0 161.0 0.0 132.6 132.7 0.1 C4-N1-C5-C6 77.2 77.2 0.0 72.6 72.6 0.0 83.7 83.8 0.1 C5-C6-N2-C10 79.4 79.4 0.0 79.0 79.1 0.1 C6-N2-C10-C9 151.8 151.8 0.0 134.9 134.9 0.0 N2-C10-C9-O4 61.3 61.4 0.1 52.1 52.2 0.1

*Density Functional Theory Calculations*

*Comparison of calculated and experimental torsion angles (°) of ligand in the complexes (1–3).*

**Name of the Complex (4) Complex (5) Complex (6) Atoms Theo. Exp. Dev. Theo. Exp. Dev. Theo. Exp. Dev.** Complex 55.6 55.7 0.1 32.3 32.3 0.0 43.4 43.5 0.1 O1-C1-C2-N1 152.7 152.6 0.1 143.9 143.9 0.0 162.3 162.4 0.1 C1-C2-N1-C5 80.2 80.2 0.0 86.1 86.1 0.0 92.7 92.8 0.1 C2-N1-C5-C6 64.0 63.9 0.1 43.6 43.6 0.0 50.1 50.1 0.0 N1-C5-C6-N2 165.5 165.4 0.1 146.4 146.4 0.0 156.5 156.7 0.2 C5-C6-N2-C8 85.7 85.7 0.0 156 155.9 0.1 89.6 89.9 0.3 C6-N2-C8-C7 60.3 60.4 0.1 44.7 44.7 0.0 30.4 30.4 0.0 N2-C8-C7-O3 59.7 59.8 0.1 17.4 17.4 0.0 47.8 48.1 0.3 O2-C3-C4-N1 91.0 91.1 0.1 112.7 112.7 0.0 135.1 135.2 0.1 C3-C4-N1-C5 156.0 156.0 0.0 159.1 159.2 0.1 151.9 151.9 0.0 C4-N1-C5-C6 72.4 72.5 0.1 97.4 97.4 0.0 92.1 92.4 0.3 C5-C6-N2-C10 156.6 156.6 0.0 151.8 151.8 0.0 143.4 143.9 0.5 C6-N2-C10-C9 59.2 59.3 0.1 41.6 41.7 0.1 5.1 4.9 0.3 N2-C10-C9-O4 55.6 55.7 0.1 32.3 32.3 0.0 43.4 43.5 0.1

**Table 3.**

**Table 4.**

**Figure 2.**

*(a) Optimized geometric structure of [Ca(THPEN)(H2O)2] 2+ (2) (b) distorted square-antiprismatic geometry.*

deviation has been observed in bond length (M-L), torsion angle of ligand THPEN and bond angles (L-M-L) of computed title complex (**4**) and crystallographically determined complex [Na(THPEN)]2(PIC)2 (**Tables 2** and **4** and **Table S1**,

*Quantum Computational Chemistry: Modeling and Calculation of S-Block Metal Ion Complexes*

*2+(4) (b) distorted monocapped octahedron geometry.*

**Figures S4a,b**). The HOMO-LUMO study has revealed that in the title complex (**4**) HOMO is mainly concentrated on bridged hydroxyl oxygens and sodium metal but to a smaller extent on the other coordinated hydroxyl oxygens and amine nitrogens. LUMO is mainly concentrated on bridged hydroxyl oxygens and to a smaller extent

Sr(II) is nine-coordinated in its dimeric complex (**5**) (**Figure 5**). This cationic complex is having tricapped trigonal-prismatic geometry as is found in crystallographically determined complex [Sr(THPEN)(H2O)2]2(DNP)4. Each Sr2+ ion in the complex is coordinated by six potential donor sites of the ligand THPEN and four water molecules. Out of four water molecules, two are bridging and the third one is non-bridging. Sr … Sr non bridging distance is 4.346 Å indicating the existence of van der Waals contact. All strain energy minimized structures reproduced the observed X-ray structures to a maximum tolerance of 9.07° bond angle (**Table 2** and **Table S1**, **Figure S5a,b**). Almost no deviation of M-L bond length and torsion angle of ligand THPEN has been observed for the title complex (**5**) and crystallographically determined complex (**Tables 2** and **4**). The HOMO-LUMO analysis has shown that the complex (**5**) is having maximum distribution of HOMO and LUMO

on other coordinated oxygen atoms. The HOMO-LUMO gap is 0.261 eV

on bridged coordinated water molecules and there is HLG of 0.0225 eV

Ba(II) is ten-coordinate in the cationic title complex (**6**) as is found in the crystallographic determined complex [Ba(THPEN)(H2O)2](DNP)4. The geometry around Ba(II) is bicapped cubic. Each Ba(II) in dimer is interacting with THPEN through all its six potential donor sites and four water molecules. The latter are

*2+ (6)*

*2+ (5)*

(**Figure S4c**).

**Figure 4.**

(**Figure S5c**).

**19**

*3.1.6 [Ba(THPEN)(H2O)2]2*

*3.1.5 [Sr(THPEN)(H2O)2]2*

*(a) Optimized geometric structure of [Na(THPEN)]2*

*DOI: http://dx.doi.org/10.5772/intechopen.90531*

**Figure 3.** *(a) Optimized geometric structure of Ba(THPEN)(PIC)2 (3) (b) bicapped square-antiprismatic geometry.*

(**Tables 1** and **3** and S1, **Figure S3a,b**). An analysis of HOMO-LUMO has illustrated that HOMO is mainly distributed on the ligand THPEN with a small distribution on coordinated picrates. In contrast to this LUMO is mainly distributed on coordinated picrates with no distribution over the ligand or metal atom. The complex is showing HLG of 0.118 eV (**Figure S3c**).

#### *3.1.4 [Na(THPEN)]2 2+ (4)*

**Figure 4a** shows the optimized structure of the cationic complex of sodium (**4**). This structure is centrosymmetric dimer. The coordination number around each Na<sup>+</sup> ion is seven. Each THPEN ligand coordinates to Na(I) ion in a heptadenate fashion (**Figure 4**). In other words, one hydroxyl group of the THPEN ligand acts as a bridge between two Na<sup>+</sup> ions. The geometry of the complex is distorted monocapped octahedron. The Na … Na non bridging distance is 3.429 Å. Almost no

*Quantum Computational Chemistry: Modeling and Calculation of S-Block Metal Ion Complexes DOI: http://dx.doi.org/10.5772/intechopen.90531*

#### **Figure 4.**

*(a) Optimized geometric structure of [Na(THPEN)]2 2+(4) (b) distorted monocapped octahedron geometry.*

deviation has been observed in bond length (M-L), torsion angle of ligand THPEN and bond angles (L-M-L) of computed title complex (**4**) and crystallographically determined complex [Na(THPEN)]2(PIC)2 (**Tables 2** and **4** and **Table S1**, **Figures S4a,b**). The HOMO-LUMO study has revealed that in the title complex (**4**) HOMO is mainly concentrated on bridged hydroxyl oxygens and sodium metal but to a smaller extent on the other coordinated hydroxyl oxygens and amine nitrogens. LUMO is mainly concentrated on bridged hydroxyl oxygens and to a smaller extent on other coordinated oxygen atoms. The HOMO-LUMO gap is 0.261 eV (**Figure S4c**).

#### *3.1.5 [Sr(THPEN)(H2O)2]2 2+ (5)*

Sr(II) is nine-coordinated in its dimeric complex (**5**) (**Figure 5**). This cationic complex is having tricapped trigonal-prismatic geometry as is found in crystallographically determined complex [Sr(THPEN)(H2O)2]2(DNP)4. Each Sr2+ ion in the complex is coordinated by six potential donor sites of the ligand THPEN and four water molecules. Out of four water molecules, two are bridging and the third one is non-bridging. Sr … Sr non bridging distance is 4.346 Å indicating the existence of van der Waals contact. All strain energy minimized structures reproduced the observed X-ray structures to a maximum tolerance of 9.07° bond angle (**Table 2** and **Table S1**, **Figure S5a,b**). Almost no deviation of M-L bond length and torsion angle of ligand THPEN has been observed for the title complex (**5**) and crystallographically determined complex (**Tables 2** and **4**). The HOMO-LUMO analysis has shown that the complex (**5**) is having maximum distribution of HOMO and LUMO on bridged coordinated water molecules and there is HLG of 0.0225 eV (**Figure S5c**).

#### *3.1.6 [Ba(THPEN)(H2O)2]2 2+ (6)*

Ba(II) is ten-coordinate in the cationic title complex (**6**) as is found in the crystallographic determined complex [Ba(THPEN)(H2O)2](DNP)4. The geometry around Ba(II) is bicapped cubic. Each Ba(II) in dimer is interacting with THPEN through all its six potential donor sites and four water molecules. The latter are

(**Tables 1** and **3** and S1, **Figure S3a,b**). An analysis of HOMO-LUMO has illustrated that HOMO is mainly distributed on the ligand THPEN with a small distribution on coordinated picrates. In contrast to this LUMO is mainly distributed on coordinated picrates with no distribution over the ligand or metal atom. The complex is showing

*(a) Optimized geometric structure of Ba(THPEN)(PIC)2 (3) (b) bicapped square-antiprismatic geometry.*

*2+ (2) (b) distorted square-antiprismatic*

**Figure 4a** shows the optimized structure of the cationic complex of sodium (**4**). This structure is centrosymmetric dimer. The coordination number around each Na<sup>+</sup> ion is seven. Each THPEN ligand coordinates to Na(I) ion in a heptadenate fashion (**Figure 4**). In other words, one hydroxyl group of the THPEN ligand acts as

monocapped octahedron. The Na … Na non bridging distance is 3.429 Å. Almost no

a bridge between two Na<sup>+</sup> ions. The geometry of the complex is distorted

HLG of 0.118 eV (**Figure S3c**).

*2+ (4)*

*(a) Optimized geometric structure of [Ca(THPEN)(H2O)2]*

*Density Functional Theory Calculations*

*3.1.4 [Na(THPEN)]2*

**Figure 2.**

*geometry.*

**Figure 3.**

bridging in nature. The existence of van der Waals contact between non-bridging Ba … Ba is indicated by their larger distance (4.196 Å). The observed and calculated positions of the metal and donor atoms are in agreement as almost negligible deviation of M-L bond length and torsion angle of THPEN. A deviation of 0.14° of bond angle L-M-L has been observed for complex (**6**) [Ba(THPEN)(H2O)2](DNP)4 (**Tables 2** and **4** and **Table S1**; **Figures S6a,b** and **S7**). The region of distribution of HOMO and LUMO is only over two of the bridged water molecules in complex (**6**) with a very small HOMO-LUMO gap (ΔE = 0.0375 eV) indicating the soft nature of complex (**Figure 6**).

copper, silver and lanthanoid [25–27] (**Table 5**). It has been observed in the present computational study that the dinitrophenolate complexes are softer than trinitrophenolate and among the latter, [Ca(THEEN)(PIC)]<sup>+</sup> (**1**) is displaying least softness. It is pertinent to mention here that the complex (**1**) is having THEEN ligand

*Quantum Computational Chemistry: Modeling and Calculation of S-Block Metal Ion Complexes*

Nuclear magnetic resonance spectra (NMR) and infrared (IR) spectroscopy can

**HLG (eV)**

3.619

2.530

2.640

**Theo. Exp. Theo. Exp.**

**Reported complexes HLG**

3.537 [La(THEEN)(PIC) (H2O)2] (PIC)2.2H2O

3.467 [La(TEAH3)(H2O)2] (PIC)3 3.673

**(eV)**

3.428

be useful for studying the coordination of various ligating sites. The 13C-NMR spectra were predicted for complexes (**1–6**) using DFT/B3LYP/6-31G\*\* method and the spectral data was compared with experimental data reported in literature [35]. The computed NMR spectral data is fairly in agreement with experimental data (**Tables 6** and **7**). Small deviations are due to the fact that H-bonding interactions or any type of lattice interactions are not modeled in theoretically computed structures. The terminal methyl groups in theoretically predicted complexes (**2**–**5**) are

> **Reported complexes**

(PIC)2.C3H8O

(PIC)2

(PIC)2

0.0375 [Ag(TEAH3)2] (PIC) 1.061

*Comparison of HOMO-LUMO energy gaps of complexes (1–6) with earlier reported complexes [25–27].*

**Assignments (δ) [Ca(THEEN)(PIC)]<sup>+</sup> (1) Ba(THPEN)(PIC)2 (3)**

dCH3 \* \* 4.22 19.61 dCH3 4.49 19.89 dNCH2 52.31 55.03 51.73 55.34 dNCH2 43.35 55.20 dOCH2, dOCH 59.03 57.47 50.75 63.00 dArCH 113.63 124.33 117.85 124.36 p-ArCN 134.75 123.60 122.06 123.68 o-ArCN 140.68 140.78 140.98 140.78 dArCO 161.57 160.20 150.21 160.20

*Comparison of calculated and experimental 13C-NMR spectral data for complexes (1 and 3).*

0.852 [Cu(THEEN)(H2O)] (PIC)2

0.419 [Cu(THPEN)]

0.118 [Cu(TEAH3)(PIC)] (PIC).H2O

0.0225 [Ag (THPEN)]2

2+ (**4**) 0.261 [Ag (THEEN)]2

whereas THPEN is ligand in rest of the complexes (**2**–**6**).

*DOI: http://dx.doi.org/10.5772/intechopen.90531*

**HLG (eV)**

**3.3 Spectral data**

[Ca(THEEN)(PIC)]<sup>+</sup>

2+ (**2**)

2+ (**5**)

2+ (**6**)

Ba(THPEN)(PIC)2

[Na(THPEN)]2

[Sr(THPEN) (H2O)2]2

[Ba(THPEN) (H2O)2]2

[Ca(THPEN) (H2O)2]

(**1**)

(**3**)

**Table 5.**

*\* Group absent.*

**Table 6.**

**21**
