The reaction of L (MAD) with Cu 2+ and Co 2+ chlorides affords new metal complexes. The isolated solid complexes were synthesized by two different techniques i.e., chemical and tribochemical methods. Four new complexes were synthesized by direct chemical reactions of MCl 2 (M = Co 2+ and Cu 2+) with MAD in absolute EtOH. The isolated solid complexes were used as starting compounds to synthesize another four new complexes using tribochemical technique by grinding the previous complexes in the solid state with excess KI in agate mortar. The results of the isolated complexes indicate the substitution of the chloride by iodide ions during grinding and extraction of the complexes by a mixture of solvents (EtOH + MeOH). Also, the results suggest that no reduction of Cu 2+ or oxidation of Co 2+ complexes is observed. The IR spectra of the complexes suggest that L acts in a bidentate manner. Moreover, the results of electronic spectra and magnetic measurements for the chloride and iodide complexes suggest distorted-octahedral and/or tetrahedral for Cu 2+ and high-spin octahedral and/or tetrahedral structures around the Co 2+ ion, respectively.
Malonic acid dihydrazide (MDH; L) is a vital class of ligands in coordination chemistry and finds extensive applications in different fields [
All the chemicals (salts and solvents) were purchased from Aldrcih and used without purification. Malonic acid dihydrazide (MAH, L) was synthesized by refluxing equivalent amounts of diethyl malonate (15.2 ml) in EtOH and hydrazine hydrate (6.2 ml) on water bath for 4 hrs. The white product (m.p.; 152˚C - 156˚C; yield: 90%) was obtained by cooling and the product was characterized by chemical and spectral methods. The ligand (MAH, L) was crystallized from absolute EtOH.
Four solid complexes derived from the reaction of CuCl2 and CoCl2 dissolved in EtOH (25 ml with L in 50 ml EtOH with the general formulae, [Cu(L)Cl2], [Co2(L)2(H2O)Cl]Cl, [Cu(L)3]Cl3∙½EtOH and [Co(L)3]Cl2, were synthesized and characterized. The reaction mixtures were refluxed on a water bath for 1 hr. The complexes were filtered off, washed several times with absolute EtOH followed by dry diethyl ether and finally dried in a vacuum desiccator over anhydrous P4O10.
[Cu(L)Cl2] is olive-green in color. Anal. Calcd: for C3H8CuN4O2Cl2 (266.6): C, 13.5; H, 3.0; N, 21.0; Cu, 23.8; Cl, 12.9%. Found: C, 12.9; H, 2.8; N, 20.6; Cu, 23.4; Cl, 12.2%.; Yield 85%; green powder; m.p.; 168˚C; Yield: 90%; Ʌ+m (DMSO): 9 ohm−1∙cm2∙mol−1 and μeff (2.0 BM).
[Co(L)2(H2O)Cl]Cl is pink in color. Anal. Calcd: for C6H18Co2N8O5Cl2 (412.118): C, 17.5; H, 4.4; N, 27.2; Co, 14.3; Cl, 17.2%. Found: C, 17.2; H, 4.1; N, 27.1; Co, 14.3; Cl, 17.2%.; m.p.; 218˚C; Yield: 86 %; Ʌ+m (DMSO): 55 ohm−1∙cm2∙mol−1 and μeff (5.2 BM).
[Cu(L)3]Cl2∙½EtOH is brown in color. Anal. Calcd: for C10H27CuN12O6Cl2 (553.868): C, 21.7; H, 4.9; N, 30.3; Cu, 11.5; Cl, 12.8%. Found: C, 21.6; H, 4.8; N, 30.8; Cu, 11.1; Cl, 12.6%.; m.p.; 254˚C; Yield: 90 %; Ʌ+m (DMSO): 70 ohm−1∙cm2∙mol−1 and μeff (2.0 BM).
[Co(L)3]Cl2 is violet in color. Anal. Calcd: for C10H27CoN12O6Cl2 (526.223): C, 20.5; H, 4.6; N, 31.9; Co, 11.2; Cl, 13.5%. Found: C, 20.4; H, 5.0; N, 31.2; Co, 10.9; Cl, 13.3%.; m.p.; 184˚C; Yield: 80 %; Ʌ+m (DMSO): 75 ohm−1∙cm2∙mol−1 and μeff (4.9 BM).
The Cu2+ and Co2+ complexes (0.5 g) synthesized from the previous method were grinded with KI (6 g) for 2 hrs until the color of the original complex is changed. A mixture of MeOH (80 ml) and EtOH (20 ml) was then added and the solution was refluxed for 2hrs and then left overnight. The isolated complexes with the general formulae; [Cu(L)I2]∙2H2O, [Co(L)2I2]∙2H2O, [Co(L)3]I2∙½EtOH∙2H2O and [Cu(L)3]I2; were filtered off, washed with 100 ml of a mixture of EtOH and H2O (1:1) and finally dried in an oven at 80˚C; Yield: 78% - 88%.
[Cu(L)I2]∙2H2O is pale yellow in color. Anal. Calcd: for C3H12CuN4O3I2 (485.509): C, 7.4; H, 2.5; N, 11.5; Cu, 13.1; I, 52.3%. Found: C, 6.7; H, 1.9; N, 11.1; Cu, 13.0; I, 52.1%.; m.p.; 210˚C; Yield: 78%; Ʌ+m (DMSO): 8 ohm−1∙cm2∙mol−1 and μeff (1.8 BM).
[Co(L)(H2O)2I2] is simon in color. Anal. Calcd: for C6H20CoN4O4I2 (613.028): C, 11.8; H, 3.3; N, 18.3; Co, 9.6; I, 41.4%. Found: C, 11.8; H, 2.8; N, 17.7; Co, 9.3; I, 40.9%.; m.p.; 196˚C; Yield: 82%; Ʌ+m (DMSO): 5 ohm−1∙cm2∙mol−1 and μeff (4.9 BM).
[Co(L)3]I2∙½EtOH∙2H2O is buff in color. Anal. Calcd: for C10H27CoN12O6I2 (768.192): C, 15.6; H, 4.1; N, 21.9; Co, 7.7; I, 33.0%. Found: C, 15.4; H, 3.7; N, 21.2; Co, 7.2; I, 32.4%.; m.p.; 238˚C; Yield: 88%; Ʌ+m (DMSO): 66 ohm−1∙cm2∙mol−1 and μeff (5.0 BM).
[Cu(L)3]I2 is brown in color. Anal. Calcd: for C9H24CuN12O6I2 (713.278): C, 15.1; H, 3.4; N, 23.6; Cu, 8.9; I, 35.6%. Found: C, 14.7; H, 2.8; N, 22.8; Cu, 8.1; I, 35.1%.; m.p.; 245˚C; Yield: 75%; Ʌ+m (DMSO): 59 ohm−1∙cm2∙mol−1 and μeff (1.78 BM).
Elemental analyses contents (C, H and N) were determined at the Microanalytical Unit, Center of King Fahd Institute at Jeddah, Saudi Arabia. Copper and cobalt contents were determined by complexometric titration in the presence of Xylenol orange as an indicator [
Χ d i a . ( molar ) = ∑ n A χ A + ∑ λ
where
χA = gram atomic susceptibility of atom A.
nA = is the number of atom A in the compound.
λ = constitutive for certain bond types.
All the isolated metal complexes are colored, stable against light and air for two years. Also, the complexes are insoluble in most common organic solvents but easily soluble in DMF and DMSO. The molar conductivities for all the iodide complexes are non-conducting except the two complexes with the general formulae, [Cu(L)3]I2 and [Co(L)3]I2∙½EtOH∙2H2O, which are conducting and have values 75 and 88 Ω−1∙cm2∙mol−1 in DMSO, respectively. On the other hand, the molar conductance of the chloride complexes in DMSO falls in the 55 - 75 Ω−1∙cm2∙mol−1 indicating 1:1 and 1:2 electrolytes, respectively. The low value (9 Ω−1∙cm2∙mol−1) for [Cu(L)Cl2] indicates that the complex is non-electrolytic [
The IR spectrum of L in KBr (
groups are taken part in hydrogen bonding. The results suggest that the first type of the hydrogen bonding (O-H…N) is more likely occurred. All these foundations suggest that L (MDH) can be represented in
The mode of bonding was determined by comparing the IR spectra of L with its complexes (Cu2+ and Co2+). The IR spectra of the complexes obtained by chemical method with the general formulae, [Cu(L)Cl2] (
The 1H-NMR spectrum of L in d6-DMSO displays four signals at 10.3, 9.9, 9.3 and 3.9, relative to TMS (
The Cu2+ and Co2+ complexes with the general formulae, [Cu(L)Cl2] (
[Cu(L)3]Cl2∙½EtOH, shows a band at 14368 cm−1 attributed to 2Eg → 2T2g transition [
Compound | ν(OH) solvent | νas(NH2) | νs(NH2) | ν(NH) | ν(CO) | ν(N-C-O) | ν(M-N) |
---|---|---|---|---|---|---|---|
L1,MDH | - | 3320 | 3156 | 2945 | 1705sh | 1494 | ---- |
[Cu(L)Cl2] | - | 3487 | 3209 | 3114 | 1689 | 1602 | 430 |
[Co(L)2(H2O)Cl]Cl | - | 3467 | 3370 | 3330 | 1650 | 1550 | 453 |
[Cu(L)3]Cl2∙½EtOH | 3444 | 3410 | 3194 | - | 1642 | 435 | |
[Co(L)3]Cl2 | - | 3447 | 3200 | 3055 | 1669 | 1628 | 440 |
[Cu(L)I2]∙2H2O | 3445 | 3411 | 3278 | - | 1661 | 429 | |
[Co(L)(H2O)2I2] | - | 3435 | 3320 | 3090 | 1660 | 1615 | 435 |
[Co(L)3]I2∙½EtOH∙2H2O | 3450 | 3420 | 3365 | 3130 | 1675 | 1620 | 425 |
[Cu(L)3]I2 | - | 3410 | 3320 | 3110 | 1660 | 1610 | 440 |
no oxidation of Co2+ to Co3+ ion as reported earlier by Mostafa et al. [
In continuation of our earlier work on tribochemical reactions and the role of metal ions as well as the ligand used in reduction of Cu2+ and oxidation of Co2+, we extend our work to include malonic acid dihydrazide (L) with Cu2+ and Co2+ by chemical and tribochemical reactions. The ligand coordinates in a bidentate manner towards the metal ions. Also, the results indicate the substitution of the chloride by iodide ions has occurred in Cu2+ and Co2+ complexes. Moreover, the reduction of Cu2+ to Cu+ and the oxidation of Co2+ to Co3+ have not been occurred and confirmed by chemical, spectral and magnetic measurements.
Al-Ashqar, S.M. (2018) Comparative Studies of New Complexes Synthesized by Chemical and Tribochemical Reactions Derived from Malonic Acid Dihydrazide (L; MAD) with Cu2+ and Co2+ Salts. Open Journal of Inorganic Chemistry, 8, 28-42. https://doi.org/10.4236/ojic.2018.81003