**3.2 HOMO-LUMO analyses**

Smaller is the HUMO-LUMO gap (HLG) softer is the complex [36, 37]. The frontier orbitals HOMO and LUMO are very important parameters for chemical reaction and take part in chemical stability [38–40]. It is predicted from the HOMO-LUMO gaps that the title complexes are soft as is obvious from their smaller HUMO-LUMO energy gaps (HLG) relative to the similar reported complexes of

**Figure 5.**

*(a) Optimized geometric structure of [Sr(THPEN)(H2O)2]2(DNP)4 (b) Trigonal- prismatic geometry.*

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

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

#### **3.3 Spectral data**

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

Smaller is the HUMO-LUMO gap (HLG) softer is the complex [36, 37]. The frontier orbitals HOMO and LUMO are very important parameters for chemical reaction and take part in chemical stability [38–40]. It is predicted from the

HOMO-LUMO gaps that the title complexes are soft as is obvious from their smaller HUMO-LUMO energy gaps (HLG) relative to the similar reported complexes of

*(a) Optimized geometric structure of [Sr(THPEN)(H2O)2]2(DNP)4 (b) Trigonal- prismatic geometry.*

*2+ (6) (b) Bicapped cubic geometry.*

complex (**Figure 6**).

**Figure 5.**

**Figure 6.**

**20**

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

**3.2 HOMO-LUMO analyses**

*Density Functional Theory Calculations*

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


#### **Table 5.**

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


#### **Table 6.**

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


central metal ion also increases. Out of the six complexes presented, three are monomeric (**1–3**) and three are dimeric (**4–6**). The longer distances between two M … M distances in the dinuclear complexes indicate the existence of van der Waals contacts between the two s-block metal ions. All the title complexes are cationic except Ba(THPEN)(PIC)2 (**3**). The latter is tight ion-paired complex. All strain energy minimized structures obtained using quantum-chemical approach reproduced the observed X-ray structures with geometric parameters in well agreement. HOMO-LUMO studies suggest the softness of the title s-block complexes relative to the similar already reported copper, silver and lanthanoid complexes. The theoretical spectral data (13C-NMR and IR) computed using DFT and experimental data is fairly in agreement with each other. The accuracy of the results predicts that the DFT studies performed using B3LYP/6-31 g + (d,p)/LANL2DZ level of theory is the appropriate quantum-chemical method for reproducing the experimental results for the title s-block complexes. This quantum-chemical approach has potential for molecular modeling of other s-block complexes and

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

Small deviations in geometric as well as spectral parameters may be attributed to the lack of H-bonding and packing interactions within lattice which were not modeled during the computational study of the entitled s-block complexes. Moreover, the quantum-chemical approach of DFT studies has been carried out in the gaseous phase whereas the already reported experimental crystal and IR spectral data is in the solid phase while 13C-NMR spectral data is in the solution phase.

*Plot showing the deviations of theoretical and experimental (a) bond lengths (Å) and (b) bond angles (°) for*

*the complex (1) and (c) (HOMO-LUMO) of the complex (1) with energy gap.*

exploring their chemistry.

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

**Appendix**

**Figure S1.**

**23**

#### **Table 7.**

*Comparison of calculated and experimental 13C-NMR spectral data for complexes (2, 4–6).*


#### **Table 8.**

*Comparison of calculated and experimental IR spectral data for complexes (1–3).*


#### **Table 9.**

*Comparison of calculated and experimental IR spectral data for complexes (4–6).*

displaying quiet high upfield shifts relative to the experimentally obtained due to more free movements in the gaseous phase than in solution or solid phase.

The computed IR spectral peaks that appear in the range of 1370–600 cm<sup>1</sup> are fairly in agreement with the experimental data (**Tables 8** and **9**). The absorption peaks due to the presence of hydroxyl groups were observed only for complexes (**1**) and (**6**) in the computed IR spectra. It is pertinent to mention here that both of these complexes possess the picrate anion in their coordination sphere. The less extent of H-bonding is reported in the crystallographic description of these complexes [35]. The theoretical absorption band appears at 3223 and 3235 cm<sup>1</sup> for both complexes (**1**) and (**6**) whereas the experimental band is reported at 3300 cm<sup>1</sup> for both of them [35].

#### **4. Conclusions**

The coordination number of the title s-block complexes is varying from 7 to 10 in the present work. As the size of the metal increases, coordination number of

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

central metal ion also increases. Out of the six complexes presented, three are monomeric (**1–3**) and three are dimeric (**4–6**). The longer distances between two M … M distances in the dinuclear complexes indicate the existence of van der Waals contacts between the two s-block metal ions. All the title complexes are cationic except Ba(THPEN)(PIC)2 (**3**). The latter is tight ion-paired complex. All strain energy minimized structures obtained using quantum-chemical approach reproduced the observed X-ray structures with geometric parameters in well agreement. HOMO-LUMO studies suggest the softness of the title s-block complexes relative to the similar already reported copper, silver and lanthanoid complexes. The theoretical spectral data (13C-NMR and IR) computed using DFT and experimental data is fairly in agreement with each other. The accuracy of the results predicts that the DFT studies performed using B3LYP/6-31 g + (d,p)/LANL2DZ level of theory is the appropriate quantum-chemical method for reproducing the experimental results for the title s-block complexes. This quantum-chemical approach has potential for molecular modeling of other s-block complexes and exploring their chemistry.

Small deviations in geometric as well as spectral parameters may be attributed to the lack of H-bonding and packing interactions within lattice which were not modeled during the computational study of the entitled s-block complexes. Moreover, the quantum-chemical approach of DFT studies has been carried out in the gaseous phase whereas the already reported experimental crystal and IR spectral data is in the solid phase while 13C-NMR spectral data is in the solution phase.

### **Appendix**

#### **Figure S1.**

*Plot showing the deviations of theoretical and experimental (a) bond lengths (Å) and (b) bond angles (°) for the complex (1) and (c) (HOMO-LUMO) of the complex (1) with energy gap.*

displaying quiet high upfield shifts relative to the experimentally obtained due to more free movements in the gaseous phase than in solution or solid phase.

ν (NO2) 1366 1371.21 1330 1329.24 1340 1329.43 δ (]CH) 790 784.54 760 762.52 790 787.17

for both of them [35].

**Assignment (δ) [Ca(THPEN)**

*Density Functional Theory Calculations*

*\* Group absent.*

**Assignments (cm<sup>1</sup>**

**Assignments (cm<sup>1</sup>**

**Table 7.**

**Table 8.**

**Table 9.**

**(H2O)2]**

**2+ (2)**

**[Na(THPEN)]2**

**<sup>+</sup> (4)**

dCH3 11.35 18.79 4.01 20.30 3.77 18.31 27.02 18.35 dCH3 11.38 19.02 5.63 20.36 3.85 18.59 27.69 18.63 dNCH2 39.60 50.99 43.05 50.42 43.60 48.31 61.69 59.80 dNCH2 39.61 51.76 44.05 52.90 57.81 59.68 61.69 60.59 dOCH \* \* 50.73 55.73 41.85 60.62 60.37 60.66 dOCH 69.24 61.74 57.90 55.95 51.91 61.08 60.38 62.53

*Comparison of calculated and experimental 13C-NMR spectral data for complexes (2, 4–6).*

ν (NO2) 1363.56 1360 m 1320.81 1360 vs 1384.20 1370 δ (]CH) 696.80 700 m 784.16 790 m 800 800

**) [Ca(THEEN)(PIC)]<sup>+</sup> (1)**

*Comparison of calculated and experimental IR spectral data for complexes (1–3).*

*Comparison of calculated and experimental IR spectral data for complexes (4–6).*

**2+**

**) [Na(THPEN)]2**

**(4)**

**2**

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

**[Ca(THPEN)(H2O)2]**

**(2)**

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

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

**(5)**

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

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

**2+ (5)**

**2+**

**2+**

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

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

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

**(6)**

**2+**

**2+ (6)**

**4. Conclusions**

**22**

The computed IR spectral peaks that appear in the range of 1370–600 cm<sup>1</sup> are fairly in agreement with the experimental data (**Tables 8** and **9**). The absorption peaks due to the presence of hydroxyl groups were observed only for complexes (**1**) and (**6**) in the computed IR spectra. It is pertinent to mention here that both of these complexes possess the picrate anion in their coordination sphere. The less extent of H-bonding is reported in the crystallographic description of these complexes [35]. The theoretical absorption band appears at 3223 and 3235 cm<sup>1</sup> for both complexes (**1**) and (**6**) whereas the experimental band is reported at 3300 cm<sup>1</sup>

The coordination number of the title s-block complexes is varying from 7 to 10 in the present work. As the size of the metal increases, coordination number of

**Figure S2.**

*Plot showing the deviations of theoretical and experimental (a) bond lengths (Å) and (b) bond angles (°) for the complex (2) (c) (HOMO-LUMO) of the complex (2) with energy gap.*

**Figure S4.**

**Figure S5.**

**25**

*Plot showing the deviations of theoretical and experimental (a) bond lengths (Å) and (b) bond angles (°) for*

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

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

*Plot showing the deviations of theoretical and experimental (a) bond lengths (Å) and (b) bond angles (°) for*

*the complex (5) (c) (HOMO-LUMO) of the complex (5) with energy gap.*

*the complex (4) (c) (HOMO-LUMO) of the complex (4) with energy gap.*

*Plot showing the deviations of theoretical and experimental (a) bond lengths (Å) and (b) bond angles (°) for the complex (3) (c) (HOMO-LUMO) of the complex (3) with energy gap.*

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

**Figure S4.**

**Figure S2.**

**Figure S3.**

**24**

*Plot showing the deviations of theoretical and experimental (a) bond lengths (Å) and (b) bond angles (°) for*

*Plot showing the deviations of theoretical and experimental (a) bond lengths (Å) and (b) bond angles (°) for*

*the complex (3) (c) (HOMO-LUMO) of the complex (3) with energy gap.*

*the complex (2) (c) (HOMO-LUMO) of the complex (2) with energy gap.*

*Density Functional Theory Calculations*

*Plot showing the deviations of theoretical and experimental (a) bond lengths (Å) and (b) bond angles (°) for the complex (4) (c) (HOMO-LUMO) of the complex (4) with energy gap.*

*Plot showing the deviations of theoretical and experimental (a) bond lengths (Å) and (b) bond angles (°) for the complex (5) (c) (HOMO-LUMO) of the complex (5) with energy gap.*

**Bond distances (Å)**

Complex (**2)**

**27**

**Theoretical Experimental Dev. Bond**

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

**angles (°)**

Ca-O1W 2.439 2.439 0.000 N1-Ca-O1WA 143.89 143.89 0.00

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

Ca-O1 2.45 2.41 0.04 O1-Ca-O2 94.43 102.08 7.65 Ca-O2 2.45 2.38 0.07 O1-Ca-O3 172.00 175.21 3.21 Ca-O3 2.41 2.48 0.07 O1-Ca-O4 85.56 74.35 11.21 Ca-O4 2.41 2.37 0.04 O1-Ca-O12 107.80 104.18 3.62 Ca-O12 2.31 2.30 0.01 O1-Ca-O13 61.91 64.85 2.94 Ca-O13 2.47 2.73 0.26 O1-Ca-N1 65.93 68.50 2.57 Ca-N1 2.74 2.59 0.15 O1-Ca-N2 104.33 115.49 11.16 Ca-N2 2.82 2.65 0.17 O2-Ca-O3 90.99 79.27 11.72

**Theoretical Experimental Dev.**

O1-Ca-O2 102.93 102.95 0.02 O1-Ca-N1 67.80 67.79 0.01 O1-Ca-O1W 79.82 79.85 0.03 O1-Ca-N1A 132.22 132.22 0.00 O1-Ca-O2A 84.37 84.36 0.01 O1-Ca-O1A 159.11 159.10 0.01 O1-Ca-O1WA 83.52 83.54 0.02 O2-Ca-N1 65.50 65.52 0.02 O2-Ca-O1W 74.11 74.10 0.01 O2-Ca-N1A 81.42 81.40 0.02 O2-Ca-O2A 139.33 139.89 0.56 O2A-Ca-O1W 145.88 145.90 0.02

O2-Ca-O4 180.00 168.65 11.35 O2-Ca-O12 108.06 107.20 0.86 O2-Ca-O13 61.38 69.92 8.54 O2-Ca-N1 64.20 68.43 4.23 O2-Ca-N2 114.39 105.72 8.67 O3-Ca-O4 89.01 105.24 16.23 O3-Ca-O12 75.95 71.06 4.89 O3-Ca-O13 126.03 110.69 15.34 O3-Ca-N1 111.54 116.18 4.64 O3-Ca-N2 67.97 68.26 0.29 O4-Ca-O12 71.93 84.20 12.27 O4-Ca-O13 118.62 116.91 1.71 O4-Ca-N1 115.80 100.38 15.42 O4-Ca-N2 65.61 67.36 1.75 O12-Ca-O13 71.32 62.19 9.13 O12-Ca-N1 168.56 169.55 0.99 O12-Ca-N2 123.47 120.54 2.93 O13-Ca-N1 97.26 107.46 10.2

#### **Figure S6.**

*Plot showing the deviations of theoretical and experimental (a) bond lengths (Å) and (b) bond angles (°) for the complex (6) (c) (HOMO-LUMO) of the complex (6) with energy gap.*




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

**Figure S7.**

**Bond distances (Å)**

**26**

Complex (**1**)

**Figure S6.**

*Plot showing the deviations of theoretical and experimental (a) bond lengths (Å) and (b) bond angles (°) for*

*the complex (6) (c) (HOMO-LUMO) of the complex (6) with energy gap.*

*Density Functional Theory Calculations*

**Theoretical Experimental Dev. Bond**

**angles (°)**

Ca-N1 2.600 2.600 0.000 N1-Ca-N1A 71.54 71.60 0.06 Ca-O1 2.387 2.388 0.001 N1-Ca-O2A 81.41 65.52 15.89 Ca-O2 2.495 2.496 0.001 N1-Ca-O1W 119.08 119.09 0.01

**Theoretical Experimental Dev.**

*R = H,THEEN; R = CH3,THPEN.*


**Bond distances (Å)**

Complex (4)

Complex(**5**)

**29**

**Theoretical Experimental Dev. Bond**

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

**angles (°)**

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

Na-N1 2.552 2.554 0.002 O1-Na-O2 99.56 99.50 0.06 Na-N2 2.565 2.566 0.001 O1-Na-O3 86.59 86.60 0.01 Na-O1 2.412 2.412 0.000 O1-Na-O4 174.34 174.30 0.04 Na-O2 2.393 2.393 0.000 O1-Na-O4A 90.18 9023 0.05 Na-O3 2.505 2.505 0.000 O1-Na-N1 69.82 69.82 0.00 Na-O4 2.628 2.629 0.001 O1-Na-N2 109.13 109.10 0.03 Na-O4A 2.442 2.443 0.001 O2-Na-O3 164.10 164.13 0.03 Na-NaA 3.429 3.430 0.001 O2-Na-O4 78.26 78.31 0.05

Sr-O1 2.617 2.618 0.001 O3-Sr-O2 151.28 158.70 7.42 Sr-O2 2.611 2.610 0.001 O3-Sr-O1 73.24 77.20 3.96 Sr-O3 2.506 2.505 0.001 O2-Sr-O1 113.98 114.30 0.32 Sr-O4 2.618 2.618 0.000 O3-Sr-O4 87.91 88.20 0.29 Sr-O1W 2.701 2.702 0.001 O2-Sr-O4 77.89 73.50 4.39 Sr-O2W 2.699 2.699 0.000 O1-Sr-O4 158.36 151.60 6.76 Sr-O2WA 2.726 2.699 0.000 O3-Sr-N1 102.34 113.60 11.26 Sr-N1 2.835 2.835 0.000 O4-Sr-N1 113.34 102.50 10.84 Sr-N2 2.849 2.849 0.000 O3-Sr-N2 61.38 64.40 3.02

**Theoretical Experimental Dev.**

O12-Ba-N1 117.95 117.96 0.01 O12-Ba-N2 143.78 143.80 0.02 O18-Ba-O6 109.54 109.60 0.06 O18-Ba-N1 140.27 140.40 0.13 O18-Ba-N2 101.49 101.50 0.01 N2-Ba-N1 61.27 61.30 0.03 N2-Ba-O6 143.21 143.20 0.01 N1-Ba-O6 102.39 102.40 0.01

O2-Na-O4A 88.56 88.57 0.01 O2-Na-N1 70.69 70.70 0.01 O2-Na-N2 121.68 121.71 0.03 O3-Na-O4 96.86 96.87 0.01 O3-Na-N1 125.19 125.17 0.02 O3-Na-N2 68.93 68.91 0.02 O3-Na-O4A 76.69 76.72 0.03 O4-Na-O4A 94.96 95.00 0.03 O4-Na-N1 68.25 68.25 0.00 O4-Na-N2 68.25 68.25 0.00 N1-Na-N2 73.38 73.37 0.01 N1-Na-O4A 147.48 147.51 0.03 N2-Na-O4A 138.85 138.87 0.02


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

**Bond distances (Å)**

**28**

Complex (**3)**

*Density Functional Theory Calculations*

**Theoretical Experimental Dev. Bond**

**angles (°)**

Ba-O1 2.720 2.720 0.000 O1-Ba-O2 86.95 87.00 0.05 Ba-O2 2.807 2.801 0.006 O1-Ba-O3 172.87 173.00 0.13 Ba-O3 2.753 2.750 0.003 O1-Ba-O4 88.55 88.50 0.05 Ba-O4 2.812 2.812 0.000 O1-Ba-O6 72.90 72.90 0.00 Ba-O5 2.681 2.683 0.002 O1-Ba-O12 61.79 61.80 0.01 Ba-O6 3.127 3.128 0.001 O1-Ba-O18 109.63 109.70 0.07 Ba-O12 2.728 2.729 0.001 O1-Ba-N1 58.12 58.10 0.02 Ba-O18 2.977 2.979 0.002 O1-Ba-N2 114.85 114.80 0.05 Ba-N1 3.038 3.038 0.000 O2-Ba-O4 129.37 129.40 0.03 Ba-N2 3.026 3.028 0.002 O2-Ba-O6 64.79 64.80 0.01

**Theoretical Experimental Dev.**

O13-Ca-N2 163.73 175.60 11.87 N1-Ca-N2 67.95 69.92 1.97

O2-Ba-O18 161.62 160.60 0.02 O2-Ba-N2 79.36 79.40 0.03 O2-Ba-N1 57.03 57.12 0.05 O3-Ba-O2 92.08 92.10 0.02 O3-Ba-O4 86.61 86.70 0.09 O3-Ba-O6 113.02 113.10 0.08 O3-Ba-O18 72.70 72.80 0.10 O3-Ba-N1 115.63 115.60 0.03 O3-Ba-N2 58.06 58.20 0.14 O4-Ba-O6 156.82 156.80 0.02 O4-Ba-O18 63.13 63.20 0.07 O4-Ba-N1 78.20 78.20 0.00 O4-Ba-N2 57.43 57.40 0.03 O5-Ba-O1 123.12 123.20 0.08 O5-Ba-O2 85.94 85.90 0.04 O5-Ba-O3 63.80 63.90 0.10 O5-Ba-O4 135.92 135.90 0.02 O5-Ba-O6 53.26 53.30 0.03 O5-Ba-O12 84.0 84.00 0.00 O5-Ba-O18 76.67 76.90 0.13 O5-Ba-N1 142.90 142.90 0.00 O5-Ba-N2 118.97 118.90 0.07 O12-Ba-O2 133.15 133.20 0.05 O12-Ba-O3 123.02 123.00 0.02 O12-Ba-O4 86.45 86.40 0.05 O12-Ba-O6 72.69 72.70 0.01 O12-Ba-O18 54.05 54.00 0.05


**Author details**

**Bond distances (Å)**

**Table S1.**

*(°) for complexes (1–6).*

Rakesh Kumar<sup>1</sup>

**31**

Jalandhar, Punjab, India

\* and Sangeeta Obrai<sup>2</sup>

**Theoretical Experimental Dev. Bond**

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

**angles (°)**

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

O2W-Ba-O1WA

*Comparison of selected experimental and calculated geometric parameters bond lengths (Å) and bond angles*

**Theoretical Experimental Dev.**

59.36 59.50 0.14

O2-Ba-O2W 74.74 75.00 0.26

N1-Ba-O1WA 137.03 137.20 0.17 N1-Ba-O1W 124.19 124.19 0.00 N1-Ba-O2W 106.68 106.90 0.22 N2-Ba-O1WA 123.73 124.00 0.27 N2-Ba-O1W 131.21 131.50 0.29 N2-Ba-O2W 166.91 167.00 0.10 N2-Ba-O2WA 100.84 100.87 0.03

\*Address all correspondence to: rakesh\_nitj@yahoo.co.in

provided the original work is properly cited.

1 Department of Chemistry, MCM DAV College, Kangra, Himachal Pradesh, India

2 Department of Chemistry, Dr. B.R. Ambedkar National Institute of Technology,

© 2020 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium,

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


#### **Table S1.**

**Bond distances (Å)**

*Density Functional Theory Calculations*

Complex (**6**)

**30**

Ba-O2W 2.988 2.990 -

**Theoretical Experimental Dev. Bond**

**angles (°)**

Ba-O1 2.736 2.738 0.002 O4-Ba-O1 162.70 162.90 0.20 Ba-O2 2.763 2.761 0.002 O4-Ba-O3 92.45 92.70 0.25 Ba-O3 2.756 2.757 0.001 O1-Ba-O3 79.69 80.00 0.31 Ba-O4 2.658 2.657 0.001 O4-Ba-O2 84.25 84.60 0.35 Ba-O1W 2.880 2.880 0.000 O1-Ba-O2 94.22 94.50 0.28

0.002

Ba-N1 3.009 3.002 0.007 O4-Ba-N1 107.19 107.50 0.31 Ba-N2 3.010 3.004 0.006 O1-Ba-N1 58.19 58.40 0.21

**Theoretical Experimental Dev.**

O2-Sr-N2 89.92 97.10 7.18 O1-Sr-N2 96.80 90.2 6.60 O4-Sr-N2 64.13 61.60 2.53 O3-Sr-O2W 106.07 106.40 0.33 O2-Sr-O2W 70.58 77.10 6.52 O1-Sr-O2W 129.35 140.50 11.15 O4-Sr-O2W 70.80 67.90 2.90 O2-Sr-O1W 79.52 65.40 14.12 O1-Sr-O1W 65.11 79.80 14.69 O4-Sr-O1W 136.42 127.40 9.02 O3'-Sr-O1W 126.14 127.90 1.76 O2W-Sr-O1W 70.75 71.00 0.25 O2W-Sr-N2 128.11 128.40 0.29 O1W-Sr-N2 152.06 152.40 0.34 N1-Sr-N2 64.77 65.00 0.23 O2W-Sr-N1 139.03 139.30 0.27 O1W-Sr-N1 87.52 87.80 0.28

O3-Ba-O2 148.19 148.40 0.21

O3-Ba-N1 91.90 92.00 0.01 O2-Ba-N1 59.43 59.60 0.17 O4-Ba-N2 59.95 61.10 1.15 O1-Ba-N2 103.03 103.20 0.17 O3-Ba-N2 58.68 58.80 0.12 O2-Ba-N2 93.2 93.40 0.20 N1-Ba-N2 61.84 62.00 0.16 O4-Ba-O1W 126.17 126.50 0.33 O1-Ba-O1W 66.29 66.50 0.23 O3-Ba-O1W 72.53 72.80 0.27 O2-Ba-O1W 133.50 133.80 0.30 O1-Ba-O2W 73.43 73.70 0.27 O3-Ba-O2W 131.18 131.50 0.32 *Comparison of selected experimental and calculated geometric parameters bond lengths (Å) and bond angles (°) for complexes (1–6).*
