Chemistry
Analytical grade reagents, commercially available from multiple suppliers and used without further purification, were all the chemicals used in the complex preparation. Synthesized compounds and their complexes have been characterized by elemental analysis, magnetic and spectroscopic methods (IR, 13C, 1HNMR, mass) and thermal analysis using the known apparatuses [42].
Synthesis of the ligands
Common 3-methyl-1-phenyl-5-pyrazolone synthesis technique (1)
Pure ethyl acetoacetate (0.05 mol, 6.2 mL) was mixed with pure phenyl hydrazine (0.05 mol, 5 mL), 0.5 mL of acetic acid was added, according to knowm method [42]. Methyl phenyl pyrazolone was obtained as colorless crystals, 127 °C melting point and 83.6 percent yield [27].
Specific method for preparing derivatives of 4-arylidene-3-methyl-1-phenyl-5-pyrazolone (2a-c)
The oil bath heated a mixture of 1-aryl-3-methyl-5-pyrazolone (0.01 mol, 1.74 g) and replaced aromatic aldehydes (0.012 mol) at 150–160 °C for 2-4hrs. TLC has tracked the progress of the reaction using ethyl acetate: hexane (9:1) as solvent. The mixture was cooled, triturated and washed off with ether (20 mL). The colored residue was recrystallized from ethanol to provide the corresponding 4-arylidene-3-methyl-1-phenyl-5-pyrazolone (2a-c) as colored products, respectively [28].
4-(4-dimethylamino benzylidene)-3-methyl-1-phenyl-1H-pyrazol-5(4H)-one (2a) L1.
4-(4-Thiophene)-3-methyl-1-phenyl-1Hpyrazol-5(4H)-one (2b) L2.
4-(4-methoxy benzylidene)-3-methyl-1-phenyl-1Hpyrazol-5(4H)-one (2c) L3.
4-(4-dimethylamino benzylidene)-3-methyl-1-phenyl-1H-pyrazol-5(4H)-one (2a) L1
Brick Red, mp = 170 °C, yield 83% IR (KBr, v, cm−1): 3444 (OH), 1670 (C = O), and 1550 cm−1. 1H NMR (DMSO-d6, 300 MHz): δ = 2.28 (s, 3H, CH3), 3.03 (s, 6H, -N (CH3)2), 7.14 (S, 1H, = CH-Ar), 9.66 (d, 3H, Ar–H),. Anal. Calcd for C19H19N3O (305.19): C, 74.40; H, 6.22; N 13.76; Found C, 74.23; H, 6.13; N, 13.35%.
4-(4-Thiophene)-3-methyl-1-phenyl-1Hpyrazol-5(4H)-one (2b) L2
Orange, mp = 125 °C, yield 74% IR (KBr, v, cm−1): 3448 (OH), 1681 (C = O), 1496 cm−1 (C = N) and 1056 cm−1(C = S). 1H NMR (DMSO-d6, 300 MHz): δ = 2.30 (s, 3H, CH3), 7.39 (S, 1H, = CH-Ar), 8.25 (d, 3H, Ar–H). Anal. Calcd for C15H12N2OS (268): C, 67.16; H, 4.47; N 10.44; S, 11.94; Found C, 67.00; H, 4.32; N, 10.21; S, 11.65%.
4-(4-methoxy benzylidene)-3-methyl-1-phenyl-1Hpyrazol-5(4H)-one (2c) L3
Orange, mp = 122 °C, yield 82% IR (KBr, v, cm−1): 3444 (OH), 1678 (C = O), 1508 cm−1 (C = N) and. 1H NMR (DMSO-d6, 300 MHz): δ = 1.91 (s, 3H, CH3), 3.69 (s, 3H, -OCH3), 7.20 (S, 1H, = CH-Ar), 8.71 (d, 3H, Ar–H).Anal. Calcd for C18H16N2O2 (292): C, 73.97; H, 5.47; N 9.58; Found C, 73.78; H, 5.13; N, 9.34%.
Synthesis of the complexes
The brown solid complex [Ag(L1)2(H2O)2]NO3 was prepared by adding 0.5 mmol (0.085 g) of AgNO3 in 20 ml of acetone to a stirred suspended solution 1 mmol (0.305 g) of L1 in 50 ml acetone. The reaction mixture was refluxed for 6 h, the precipitate was drained off, washed several times with acetone and dried under vacuum over anhydrous CaCl2. Dark brown [Ag(L2)2(H2O)2]NO3.H2O, [Ag(L3)2(H2O)2]NO3 solid complexes were prepared in the same manner as mentioned above.
[Ag(C19H19N3O)2(H2O)2]NO3 (AgC38H42N7O7) complex
Brown; Yield: 85%; m.p.: 160 οC; M.Wt: 816.65; Elemental analysis for AgC38H42N7O7: found, C, 55.31; H, 4.99; N, 12.00; Ag, 13.14; Calcd, C 55.89; H, 5.18; N, 12.01; Ag, 13.21; Λm = 115.75 S cm2 mol−1; IR (KBr, v, cm−1): 3450 m,br (OH), 1666 m (C = O), 1523vw cm−1(C = N) and 813w and 837w (M–N). 1H NMR (DMSO-d6, 300 MHz): δ = 2.49 (s, 3H, CH3), 3.46 (s, 2H, H2O), 2.27–2.33 (s, 6H, -N (CH3)2), 9.67 (S, 1H, = CH-Ar), 7.14–7.97 (m, 4H, Ar–H).
[Ag(C15H12N2OS)2(H2O)2]NO3.H2O (AgC30H30N5O8S2) complex
Dark brown; Yield: 74%; m.p.: 125 οC; M.Wt: 760.59; Elemental analysis for AgC30H30N5O8S2: found, C, 47.22; H, 3.91; N, 9.15; Ag, 14.13; Calcd, C, 47.37; H, 3.98; N, 9.21; Ag, 14.18; Λm = 135.50 S cm2 mol−1; IR (KBr, v, cm−1): 3444 m, br (OH), 1685 m (C = O), 1527vw cm−1 (C = N), 1099 m cm−1(C = S), 748w and 792w (M–N). 1H NMR (DMSO-d6, 300 MHz): δ = 2.49 (s, 3H, CH3), 3.37 (s, 2H, H2O), 8.64 (S, 1H, = CH-Ar), 7.20–7.94 (d, 3H, Ar–H).
[Ag(C18H16N2O2)2(H2O)2]NO3 (AgC36H36N5O9) complex
Dark brown; Yield: 90%; m.p.: 150 οC; M.Wt: 790.57; Elemental analysis for AgC36H36N5O9: found, C, 54.47; H, 4.11; N, 8.80; Ag, 13.60; Calcd, C, 54.69; H, 4.59; N, 8.86; Ag, 13.64; Λm = 114.52 S cm2 mol−1; IR (KBr, v, cm−1): 3444 (OH), 1678 (C = O), 1520 cm−1 (C = N), 759w and 779w (M–N). 1H NMR (DMSO-d6, 300 MHz): δ = 2.33 (s, 3H, CH3), 3.31 (s, 3H, -OCH3), 8.42 (S, 1H, = CH-Ar), 7.18–7.46 (d, 3H, Ar–H).