Abstract
Full Text
Chemistry
Academician of the Academy of Sciences of the Moldavian SSR A. V. Ablov, B. A. Bobylkin, N. M. Samus’
Co(III) Dioximes Containing in the Inner Sphere a Molecule of Water and a Molecule of Ammonia or an Organic Amine
Complex Co(III) cations with dimethylglyoxime and ammonia or organic amines of the type \([\mathrm{Co}(\mathrm{DH})_2\mathrm{A}_2]^+\) were described by L. A. Chugaev as early as 1905 \((^1)\). As has now been shown, they have a trans configuration \((^{2,3})\). Comparatively recently A. V. Ablov, M. P. Filippov, and N. M. Samus’ synthesized salts of trans-bis-dimethylglyoximatodiaquocobalt
\([\mathrm{Co}(\mathrm{DH})_2\cdot(\mathrm{H_2O})_2]X\) \((^4)\).
In the present communication we describe cobalt(III) dioximes containing in the inner sphere one molecule of water and one molecule of ammonia or an organic amine, of the general formula \([\mathrm{Co}(\mathrm{DH})_2(\mathrm{H_2O})\mathrm{A}]\mathrm{NO}_3\). To obtain them, an exactly calculated amount of amine is added to a cooled aqueous solution of trans-bis-dimethylglyoximatodiaquocobalt nitrate. In the case of aniline, for example, brown crystals of
\([\mathrm{Co}(\mathrm{DH})_2(\mathrm{H_2O})(\mathrm{H_2NC_6H_5})]\mathrm{NO}_3\cdot2\mathrm{H_2O}\) separated. In aqueous solution this salt behaves as a binary electrolyte and shows an acidic reaction, but it is a weaker acid than the salts of trans-bis-dimethylglyoximatodiaquocobalt. The absorption curve of a dilute aqueous solution has two absorption bands (Fig. 1). The first band in the region of 350 nm is due to the coordinated aromatic amine; the second band at \(\lambda = 250\) nm is characteristic of the planar \(\mathrm{Co}(\mathrm{DH})_2\) grouping \((^5)\).
Fig. 1. Light-absorption curves: \(a\)—1,6-\([\mathrm{Co}(\mathrm{DH})_2(\mathrm{H_2O})(\mathrm{H_2NC_6H_5})]\mathrm{NO}_3\cdot2\mathrm{H_2O}\) (\(C = 0.001\) mol); \(b\)—1,6-\([\mathrm{Co}(\mathrm{DH})_2(\mathrm{H_2NC_6H_5})_2]\mathrm{NO}_3\cdot2\mathrm{H_2O}\), from \((^6)\).
When an excess of aniline acts on the nitrate obtained by us, a substance is formed which, in crystal form and color, resembles bis-dimethylglyoximatodianilinecobalt nitrate
\([\mathrm{Co}(\mathrm{DH})_2(\mathrm{H_2NC_6H_5})_2]\mathrm{NO}_3\cdot2\mathrm{H_2O}\) \((^6)\).
The nature of this compound was confirmed by recording the light-absorption curve \((^5)\) and by converting it, under the action of alkali, into the characteristic base
\([\mathrm{Co}(\mathrm{D_2H})(\mathrm{H_2NC_6H_5})_2]\cdot3\mathrm{H_2O}\) \((^7)\).
On addition of one mole of hydrochloric acid to a concentrated aqueous solution of the salt obtained by us, a microcrystalline brown precipitate, sparingly soluble in water, immediately separates. In all its properties this compound is the nonelectrolyte
\([\mathrm{CoCl}(\mathrm{DH})(\mathrm{H_2NC_6H_5})]\cdot2\mathrm{H_2O}\) \((^8)\). Similarly, on addition of one mole of hydrobromic or hydroiodic acid, the nonelectrolytes
\([\mathrm{CoBr}(\mathrm{DH})_2(\mathrm{H_2NC_6H_5})]\cdot2\mathrm{H_2O}\) and \([\mathrm{CoI}(\mathrm{DH})_2(\mathrm{H_2NC_6H_5})]\cdot\frac{1}{2}\mathrm{H_2O}\) precipitated \((^8)\).
Since the dianilino and monoanilino dioximes \([\mathrm{Co}(\mathrm{DH})_2(\mathrm{H_2NC_6H_5})_2]^+\) and \([\mathrm{CoHal}(\mathrm{DH})_2(\mathrm{H_2NC_6H_5})]\), into which the aquoanilino complex is readily converted, have a trans configuration \((^9)\), the original cation must have the same structure. Therefore the reaction
trans-\([ \mathrm{Co}(\mathrm{DH})_2(\mathrm{H_2O})_2]^+ + \mathrm{H_2NC_6H_5} = [\mathrm{Co}(\mathrm{DH})_2(\mathrm{H_2NC_6H_5})(\mathrm{H_2O})]^+ + \mathrm{H_2O}\) is not accompanied by a change in spatial configuration.
By the method described above, cations of the type \([\mathrm{Co}(\mathrm{DH})_2(\mathrm{H_2O})A]^+\) were synthesized with amines: aniline, o-, m-, and p-toluidines, p-anisidine, pyridine, and β-picoline.
To obtain the aquoammine dioxime, to a solution of trans-\([\mathrm{Co}(\mathrm{DH})_2(\mathrm{H_2O})_2]\mathrm{NO_3}\cdot \mathrm{H_2O}\) a calculated amount of ammonium acetate was added. Under these conditions there is no excess ammonia in the solution, and therefore the cation \([\mathrm{Co}(\mathrm{DH})_2(\mathrm{NH_3})_2]^+\) is not formed.
Experimental Part
Nitrate of trans-bis-dimethylglyoximatoaquoanilinecobalt(III). \((\mathrm{Co}\cdot(\mathrm{DH})_2(\mathrm{H_2O})(\mathrm{H_2NC_6H_5}))\mathrm{NO_3}\cdot 2\mathrm{H_2O}\).
To 2.0 g of trans-\([\mathrm{Co}(\mathrm{DH})_2(\mathrm{H_2O})_2]\mathrm{NO_3}\cdot \mathrm{H_2O}\) \(^{(4)}\) 30 ml of water were added, the mixture was cooled to \(5\text{–}10^\circ\), and a solution of 0.4 ml (5 mmoles) of aniline in 20 ml of alcohol was carefully poured in. From the filtered solution, after some time, a brown precipitate separates, which under the microscope has the appearance of rectangular plates. The substance is readily soluble in water and in alcohol, less readily in ether. Yield 70% of theory. The nitrate obtained was dissolved in water at \(10^\circ\) and precipitated with sodium nitrate. For analysis, the air-dried substance was taken.
Found, %: Co 11.86; 11.88; N 16.63; 16.70; C 33.61; 33.54;
H 5.23; 5.31; H₂O 7.30
\(\mathrm{CoC_{14}H_{23}N_6O_8\cdot 2H_2O}\). Calculated, %: Co 11.82; N 16.87; C 33.73; H 5.46; H₂O 7.23
The substance may also be obtained in the following manner. 1.7 g (5 mmoles) of trans-hydroxo-bis-dimethylglyoximatoaquocobalt \([\mathrm{Co}(\mathrm{OH})(\mathrm{DH})_2\cdot(\mathrm{H_2O})]\) \(^{(4,10)}\) was covered with 30 ml of water cooled to \(5\text{–}10^\circ\), and 0.4 ml (5 mmoles) of aniline dissolved in 20 ml of ethanol was added, after which the hydroxoaquo compound rapidly dissolves. To the filtered solution, a calculated amount of concentrated nitric acid was added dropwise. A brown precipitate separated, which was transferred to a filter and washed with cold water, a small amount of alcohol, and finally with ether.
Found, %: Co 11.90; N 16.65
\(\mathrm{CoC_{14}H_{23}N_6O_8\cdot 2H_2O}\). Calculated, %: Co 11.82; N 16.87
Below are given the electrical conductivity and pH of solutions of nitrate of bis-dimethylglyoximatoaquoanilinecobalt:
| \(V\), l·mole\(^{-1}\) | \(\mu\), ohm\(^{-1}\)·l·cm\(^{-2}\) | pH |
|---|---|---|
| 250 | 100.1 | 5.00 |
| 500 | 102.2 | 5.10 |
| 1000 | 106.4 | 5.22 |
Nitrate of bis-dimethylglyoximatoaquo (p-toluidine)cobalt(III) \([\mathrm{Co}(\mathrm{DH})_2(\mathrm{H_2O})(\mathrm{H_2NC_6H_4(CH_3)})]\mathrm{NO_3}\).
The substance was obtained analogously to the preceding one, with a yield of 80% of theory. Under the microscope it has the appearance of yellow plates.
Found, %: Co 12.37; 12.39; N 17.34; 17.40
\(\mathrm{CoC_{15}H_{25}N_6O_8}\). Calculated, %: Co 12.36; N 17.65
Nitrate of bis-dimethylglyoximatoaquo (m-toluidine)cobalt(III) \([\mathrm{Co}(\mathrm{DH})_2(\mathrm{H_2O})(\mathrm{H_2NC_6H_4(CH_3)})]\mathrm{NO_3}\).
Under the microscope it has the appearance of long thin needles.
Found, %: Co 12.24; 12.30; N 17.66; 17.58
\(\mathrm{CoC_{15}H_{25}N_6O_8}\). Calculated, %: Co 12.36; N 17.65
Bis-dimethylglyoximatoaquo(o-toluidine)cobalt(III) nitrate
\([ \mathrm{Co(DH)_2(H_2O)(H_2NC_6H_4CH_3)} ]\mathrm{NO_3}\).
A light-yellow substance; under the microscope it has the appearance of long rectangular plates.
\[ \mathrm{CoC_{15}H_{25}N_6O_8}. \quad \begin{aligned} &\text{Found, \%: } && \mathrm{Co}\ 12.33;\ 12.30;\quad \mathrm{N}\ 17.55;\ 17.48\\ &\text{Calculated, \%: } && \mathrm{Co}\ 12.36;\quad \mathrm{N}\ 17.65 \end{aligned} \]
Bis-dimethylglyoximatoaquo(\(p\)-anisidine)cobalt(III) nitrate
\([ \mathrm{Co(DH)_2(H_2O)(H_2NC_6H_4OCH_3)} ]\mathrm{NO_3}\cdot 2\mathrm{H_2O}\).
A reddish substance. Under the microscope it has the appearance of square plates.
\[ \mathrm{CoC_{15}H_{25}N_6O_9}\cdot 2\mathrm{H_2O}. \quad \begin{aligned} &\text{Found, \%: } && \mathrm{Co}\ 11.27;\ 11.20;\quad \mathrm{N}\ 15.78;\ 15.75;\quad \mathrm{H_2O}\ 6.95\\ &\text{Calculated, \%: } && \mathrm{Co}\ 11.16;\quad \mathrm{N}\ 16.92;\quad \mathrm{H_2O}\ 6.82 \end{aligned} \]
Bis-dimethylglyoximatoaquopyridinecobalt(III) nitrate
\([ \mathrm{Co(DH)_2(H_2O)Py} ]\mathrm{NO_3}\).
A light-brown substance, which under the microscope has the appearance of long prisms.
\[ \mathrm{CoC_{13}H_{21}N_6O_8}. \quad \begin{aligned} &\text{Found, \%: } && \mathrm{Co}\ 13.02;\ 13.10;\quad \mathrm{N}\ 18.88;\ 18.90;\quad \mathrm{C}\ 34.96;\ 35.00\\ &&& \mathrm{H}\ 4.79;\ 4.79\\ &\text{Calculated, \%: } && \mathrm{Co}\ 13.14;\quad \mathrm{N}\ 18.75;\quad \mathrm{C}\ 34.81;\\ &&& \mathrm{H}\ 4.72 \end{aligned} \]
Bis-dimethylglyoximatoaquo(β-picoline)cobalt(III) nitrate
\([ \mathrm{Co(DH)_2(H_2O)(C_5H_4NCH_3)} ]\mathrm{NO_3}\).
Under the microscope it has the appearance of yellow long prisms.
\[ \mathrm{CoC_{14}H_{23}N_6O_8}. \quad \begin{aligned} &\text{Found, \%: } && \mathrm{Co}\ 12.74;\ 12.78;\quad \mathrm{N}\ 18.06;\ 17.75\\ &\text{Calculated, \%: } && \mathrm{Co}\ 12.75;\quad \mathrm{N}\ 18.19 \end{aligned} \]
Bis-dimethylglyoximatoaquoamminecobalt(III) nitrate
\([ \mathrm{Co(DH)_2(H_2O)(NH_3)} ]\mathrm{NO_3}\).
2.0 g (5 mmoles) of \([ \mathrm{Co(DH)_2(H_2O)_2} ]\mathrm{NO_3}\cdot \mathrm{H_2O}\) was dissolved in 30 ml of water cooled to \(5\text{–}10^\circ\); to the filtered solution, 0.35 g (5 mmoles) of ammonium acetate was added. On standing, and more rapidly upon addition of alcohol, brown crystals separated from the solution; under the microscope they have the appearance of squares. The substance is readily soluble in water, somewhat less so in alcohol and ether.
\[ \mathrm{CoC_8H_{19}N_6O_8}. \quad \begin{aligned} &\text{Found, \%: } && \mathrm{Co}\ 15.30;\ 15.31;\quad \mathrm{N}\ 21.80;\ 21.78\\ &\text{Calculated, \%: } && \mathrm{Co}\ 15.26;\quad \mathrm{N}\ 21.77; \end{aligned} \]
Kishinev State
University
Received
1 II 1965
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