I. I. Molodykh.

Complex Compounds of Amylpyridinium Bromide and Benzylpyridinium Chloride with Salts of Heavy Metals.

(Laboratory of General Chemistry).

In analytical chemistry, organic derivatives of various metals have recently been acquiring ever greater importance. The formation of such a derivative, if the latter is distinguished by poor solubility or by a special coloration, sometimes serves as the best reaction for the qualitative detection and quantitative determination of the corresponding metal.

Thus, for the determination of nickel, the reagent indicated long ago by L. I. Chugaev—dimethylglyoxime¹—is already used; magnesium is detected by means of orthooxyquinoline², chinalizarin³, or diphenylcarbazide⁴; for copper there is the characteristic reagent 5,7-dibromo-o-oxyquinoline⁵; diphenylcarbazide⁶ makes it possible to detect cadmium under suitable conditions; for the qualitative determination of cobalt, α-aminopyridine⁷ is used, etc.

The rapid and delicate methods of analysis now spreading in industrial laboratories (for example, drop analysis) are based primarily precisely on the use of organic reagents. The derivatives of organic substances formed with metal salts very often have, at least in part, a complex character. Such are the above-mentioned salt-like compounds of nickel with dimethylglyoxime or with dicyandiamidine sulfate⁸, of copper with 5,7-dibromo-o-oxyquinoline, of cobalt with α-aminopyridine, and a whole series of others.

There can be no doubt that, in the further development of analytical chemistry as well, the study of metal compounds formed by one or another organic substance will have no less, and probably still greater, importance. These considerations led me to continue the investigation, begun under the direction of Prof. Ya. I. Mikhailenko, of complexes of quaternary ammonium salts with halides of certain heavy metals.

Amines and salts of quaternary ammonium, as the literature data show, readily form compounds with a number of salts of heavy metals which, by their properties, may with equal justification be classified both as complex salts and as double salts.

The substances obtained by me:

\[ (\mathrm{C_5H_5NC_5H_{11}Br})_2 \cdot \mathrm{CuBr_2},\quad \mathrm{C_5H_5NC_5H_{11}Br} \cdot \mathrm{FeCl_3}, \]

\[ (\mathrm{C_5H_5NCH_2 \cdot C_6H_5Cl})_2 \cdot \mathrm{CuCl_2} \]

¹ Tschugaeff. B. 38, 2520. ZhRFKhO-va vol. 41.
² Hanh. Chem. Ztg 50,754. Ztschr. ang Ch. 39, 1198. Ztschr. anal. Ch. 71, 122.
³ Jäger. Ber. Deuts. Chem. Ges 57, 1394.
⁴ Feigl. Ztschr. anal. Ch. 72, 1934.
⁵ Berg. Ztschr. anal. Ch. 70, 347.
⁶ Feigl. Ztschr. anal. Ch. 62, 370.
⁷ Chim. et Ind. 32, No. 2, 295.
⁸ Grossmann u. Schück. B. 39, 3356.

and a number of others, are compounds of the type \(R_2'[\mathrm{Me}X_4'']\), where the complex cation will be an ammonium-type cation, namely: \((\mathrm{C}_5\mathrm{H}_5\mathrm{NC}_5\mathrm{H}_{11})'\) or \((\mathrm{C}_5\mathrm{H}_5\mathrm{NCH}_2\mathrm{C}_6\mathrm{H}_5)\), while the anion is formed by an ion of a heavy metal with 4 monovalent halogen ions \(\mathrm{Me}X_4''\). Thus, the compounds investigated have coordination number 4, which agrees with Kossel’s calculations, according to which the energy of complex formation upon the addition of monovalent ions will be greatest in cases where the coordination number is 4 when the charge of the central atom is equal to 2 or 3.

When two salts interact, either a complex compound or a double salt is formed, depending on the ratio of the force field of the central atom, which gives the complex ion, and of the other ion, whose charge is the same as that of the central atom. The formation of the molecule of the complex compound must be accompanied by the liberation of energy \(E\), which is composed of: 1) the energy of formation of the complex anion \(E_A\), 2) the energy of formation of the molecules of the given complex \(E_M\), and 3) the expenditure of energy for the dissociation of the molecules of the initial substances \(E_D\), i.e.:

\[ E = E_A + E_M - E_D. \]

In the case of formation of the complexes studied, we have a large energy of dissociation of the molecules of the substances taken into ions \(E_D\), and only slightly exceeding it in magnitude is the sum of the energies of formation of the complex anion \(\mathrm{Me}X_4''\) and of the molecules of the complex itself \(R_2\mathrm{Me}X_4\), i.e. \(E_A + E_M\). This may be judged from the behavior of the substance in solutions, which is especially clearly seen when colored ions are present. Thus, the blue color of concentrated solutions of the complex \((\mathrm{C}_5\mathrm{H}_5\mathrm{NC}_5\mathrm{H}_{11})_2(\mathrm{CoCl}_2\mathrm{Br}_2)\) depends on the presence of the blue ion \((\mathrm{CoCl}_2\mathrm{Br}_2)''\):

\[ (\mathrm{C}_5\mathrm{H}_5\mathrm{NC}_5\mathrm{H}_{11})_2(\mathrm{CoCl}_2\mathrm{Br}_2) \rightleftarrows 2\,\mathrm{C}_5\mathrm{H}_5\mathrm{NC}_5\mathrm{H}_{11}' + (\mathrm{CoCl}_2\mathrm{Br}_2)'' \]

Upon subsequent dilution of the solution, the complex anion \((\mathrm{CoCl}_2\mathrm{Br}_2)''\) dissociates into the ions \(\mathrm{Co}\) and \(2\mathrm{Br}'\), \(2\mathrm{Cl}'\), which causes the blue color to change to pink, belonging to the \(\mathrm{Co}\) ion.

This circumstance makes it possible to determine, without difficulty, the composition of the substances obtained. The phenomenon of a change in color upon dilution of the solution can be observed in all cases where colored ions are present.

In the present work the following complex salts are described¹:

\[ \begin{gathered} (\mathrm{C}_5\mathrm{H}_5\mathrm{NC}_5\mathrm{H}_{11}\mathrm{Br})_2 \cdot \mathrm{NiCl}_2;\\ (\mathrm{C}_5\mathrm{H}_5\mathrm{NC}_5\mathrm{H}_{11}\mathrm{Br})_2 \cdot \mathrm{CuCl}_2;\\ (\mathrm{C}_5\mathrm{H}_5\mathrm{NC}_5\mathrm{H}_{11}\mathrm{Br})_2 \cdot \mathrm{CuBr}_2;\\ (\mathrm{C}_5\mathrm{H}_5\mathrm{NC}_5\mathrm{H}_{11}\mathrm{Br})_2 \cdot \mathrm{CoCl}_2;\\ (\mathrm{C}_5\mathrm{H}_5\mathrm{NC}_5\mathrm{H}_{11}\mathrm{Br})_2 \cdot \mathrm{CdJ}_2;\\ (\mathrm{C}_5\mathrm{H}_5\mathrm{NC}_5\mathrm{H}_{11}\mathrm{Br})_2 \cdot \mathrm{CdCl}_2;\\ (\mathrm{C}_5\mathrm{H}_5\mathrm{NC}_5\mathrm{H}_{11}\mathrm{Br})_2 \cdot \mathrm{MnCl}_2;\\ (\mathrm{C}_5\mathrm{H}_5\mathrm{NC}_5\mathrm{H}_{11}\mathrm{Br}) \cdot \mathrm{FeCl}_3 \cdot \mathrm{H}_2\mathrm{O};\\ (\mathrm{C}_5\mathrm{H}_5\mathrm{NCH}_2\mathrm{C}_6\mathrm{H}_5\mathrm{Cl})_2 \cdot \mathrm{CuCl}_2;\\ (\mathrm{C}_5\mathrm{H}_5\mathrm{NCH}_2\mathrm{C}_6\mathrm{H}_5\mathrm{Cl})_2 \cdot \mathrm{CuBr}_2;\\ (\mathrm{C}_5\mathrm{H}_5\mathrm{NCH}_2\mathrm{C}_6\mathrm{H}_5\mathrm{Cl})_2 \cdot \mathrm{CoCl}_2;\\ (\mathrm{C}_5\mathrm{H}_5\mathrm{NCH}_2\mathrm{C}_6\mathrm{H}_5\mathrm{Cl})_2 \cdot \mathrm{MnCl}_2;\\ (\mathrm{C}_5\mathrm{H}_5\mathrm{NCH}_2\mathrm{C}_6\mathrm{H}_5\mathrm{Cl})_2 \cdot \mathrm{CdCl}_2;\\ \mathrm{C}_5\mathrm{H}_5\mathrm{NCH}_2\mathrm{C}_6\mathrm{H}_5\mathrm{Cl} \cdot \mathrm{FeCl}_3 \cdot \mathrm{H}_2\mathrm{O}. \end{gathered} \]

Method of Work

The method of work consisted in the following: in order to obtain the complexes, concentrated aqueous solutions of the starting substances were mixed, and the mixture was heated on a water bath until crystallization began.

The crystalline product was filtered off on a Büchner funnel and washed with alcohol. In cases where a product of doubtful purity was obtained, it was subjected to recrystallization. Melting points were determined in capillaries.

Experimental Part

I.

Complex compounds of amylpyridinium bromide with salts of heavy metals

For carrying out this part of the work, the starting substance was amylpyridinium bromide, which was prepared from freshly distilled pyridine and amyl bromide. The synthesis of this compound by Reichler’s method¹ was carried out in a flask with a ground-glass stopper, into which the starting substances were introduced in equimolecular amounts with the addition of wine spirit.

The flask with the mixture was heated in a boiling water bath for 3 hours. After 1½ hours from the beginning of the experiment, white crystals began to appear, and by the end of the 3rd hour they occupied almost the entire flask. The substance was separated from the liquid on a Büchner funnel with suction and washed twice with alcohol. It proved to consist of light, silvery-white plates, readily soluble in water, less readily in alcohol, and almost insoluble in ether. It has a high m.p. of 265°, and crystallizes from water.

Analysis gives the formula:

\[ \mathrm{C_5H_5NC_5H_{11}Br}. \]

1. No water of crystallization.

2. Bromine content:

\[ \begin{aligned} \text{Found} \quad &\mathrm{Br} = 34.55\% \\ \text{Calculated} \quad &\mathrm{Br} = 34.74\% \end{aligned} \]

Sample: 0.5822 g; \(\mathrm{AgBr} = 0.4726\) g; \(\mathrm{Br} = 0.2011\) g.

1. Carbon and hydrogen content:

\[ \begin{aligned} \text{Calculated} \quad &\mathrm{C} = 52.17\% \qquad \mathrm{H} = 7.01\% \\ \text{Found} \quad &\mathrm{C} = 51.52\% \qquad \mathrm{H} = 7.2\% \end{aligned} \]

Sample: 0.2315 g.

\[ \begin{aligned} \text{Weight of } \mathrm{CO_2} &= 0.4374\ \text{g; hence: } \mathrm{C} = 0.1193\ \text{g}.\\ \text{Weight of } \mathrm{H_2O} &= 0.1501\ \text{g; } \mathrm{H} = 0.01667\ \text{g}. \end{aligned} \]

Complex \((\mathrm{C_5H_5NC_5H_{11}Br})_2 \cdot \mathrm{CuCl_2}\)

was obtained by mixing aqueous solutions of amylpyridinium bromide and cupric chloride, calculated for two molecules of the former and one of the latter. The mixture was heated on a boiling water bath until crystallization began. The crystals that separated were black-brown in color, appearing dark red at their thin edges. Melting point 247.5°.

The analysis gave the following figures:

1. There is no water of crystallization.
2. Cu content:

Found . . . . . . . . . . . . . . . . . . . . . . $\mathrm{Cu} = 10.5\%$
Calculated . . . . . . . . . . . . . . . . . . $\mathrm{Cu} = 10.69\%$

Sample $0.5942$ g; $\mathrm{Cu}_2\mathrm{S} = 0.0782$ g.¹); $\mathrm{Cu} = 0.06238$ g.

1. Chlorine and bromine content in the complex:

Found . . . . . . . . . . . $\mathrm{Cl} = 12.05\%$  $\mathrm{Br} = 26.70\%$
Calculated . . . . . . . . $\mathrm{Cl} = 11.92\%$  $\mathrm{Br} = 26.88\%$

Sample $0.5638$ g; weight of $\mathrm{AgCl} + \mathrm{AgBr} = 0.6283$ g, converted to $\mathrm{AgCl} = 0.5492$ g.

$\mathrm{AgCl} = 0.2746$ g; $\mathrm{Cl} = 0.06792$ g, or $12.05\%$
$\mathrm{AgBr} = 0.3537$ g; $\mathrm{Br} = 0.1504$ g, or $26.7\%$

1. Determination of carbon and hydrogen by combustion gave:

Sample $0.2884$ g.

Weight of $\mathrm{CO}_2 = 0.4135$ g; $\mathrm{C} = 39.1\%$;
Weight of $\mathrm{H}_2\mathrm{O} = 0.1365$ g; $\mathrm{H} = 5.3\%$.

Calculated . . . . . . . . . . $\mathrm{C} = 40.36\%$  $\mathrm{H} = 5.42\%$
Found . . . . . . . . . . . . . . $\mathrm{C} = 39.1\%$  $\mathrm{H} = 5.3\%$

Complex $(\mathrm{C}_5\mathrm{H}_5\mathrm{NC}_5\mathrm{H}_{11}\mathrm{Br})_2 \cdot \mathrm{CuBr}_2$

obtained by the interaction of two molecules of amylpyridinium bromide with one molecule of cupric bromide. The excess solvent (water) was removed by heating on a water bath. On crystallization, black lustrous crystals separate; when ground in a mortar they give a dark-violet powder. M.p. $252.5^\circ$. Very readily soluble in water, less readily in alcohol, and insoluble in ether.

Analysis data for the complex:

1. There is no water of crystallization.
2. Copper content in the complex:

Found . . . . . . . . . . . . . . . . . . . . . . $\mathrm{Cu} = 9.18\%$
Calculated . . . . . . . . . . . . . . . . . . $\mathrm{Cu} = 9.3\%$

Sample $0.5284$ g.
$\mathrm{Cu}_2\mathrm{S} = 0.06074$ g.
$\mathrm{Cu} = 0.0485$ g, or $9.18\%$

1. Bromine content:

Found . . . . . . . . . . . . . . . . . . . . . . $\mathrm{Br} = 46.86\%$
Calculated . . . . . . . . . . . . . . . . . . $\mathrm{Br} = 46.77\%$

Sample $0.4502$ g.
Weight of $\mathrm{AgBr} = 0.4956$ g; $\mathrm{Br} = 0.2109$ g, or $46.86\%$.

Complex $(\mathrm{C}_5\mathrm{H}_5\mathrm{NC}_5\mathrm{H}_{11}\mathrm{Br})_2 \cdot \mathrm{NiCl}_2$

apple-green in color. Obtained in the same way as the preceding ones. Extremely readily soluble in water. Crystallizes with great difficulty.

¹) The determination of Cu was made by Walter’s method. Ber. 22, 3246.

Analysis data:
1. There is no water of crystallization.
2. Ni content in the complex:

Found . . . . . . . . . . . . Ni = 10.1%
Calculated . . . . . . . . . Ni = 9.85%

Sample 0.5464 g.
Weight of NiO = 0.0558 g. Weight of Ni = 0.05518 g, or 10.1%.

1. Determination of chlorine and bromine:

Found . . . . . . . . Cl = 12.15%  Br = 27.02%
Calculated . . . . . . Cl = 12.02%  Br = 27.11%

Sample 0.6324 g.
Weight of AgCl + AgBr = 0.7121 g.
Converted to AgCl = 0.6212 g.

AgCl = 0.3106 g; Cl = 0.07683 g, or 12.15%.
AgBr = 0.4015 g; Br = 0.1709 g, or 27.02%.

Complex \((\mathrm{C_5H_5NC_5H_{11}Br})_2 \cdot \mathrm{CoCl_2}\)

obtained by the interaction of aqueous solutions of amylpyridinium bromide (2 mol) and cobalt chloride (1 mol). The complex is of a beautiful cornflower-blue color. Melting point \(= 264^\circ\). Readily soluble in water, slightly in alcohol, and insoluble in ether.

Analysis data:
1. There is no water of crystallization.
2. Amount of cobalt in the complex:

Found . . . . . . . . . . . Co = 9.82%
Calculated . . . . . . . . Co = 9.99%.

Sample 0.6534 g.
Weight of Co = 0.0643 g. % Co = 9.82%.

1. Determination of chlorine and bromine:

Found . . . . . . . . Cl = 12.2%  Br = 26.8%
Calculated . . . . . . Cl = 12.01%  Br = 27.09%

Sample 0.6348 g.
Weight of AgCl + AgBr = 0.7127 g; converted to AgCl = 0.6262 g.
AgCl = 0.3131 g; Cl = 0.07745 g, or 12.2%.
AgBr = 0.3996 g; Br = 0.1701 g, or 26.8%.

Complex \((\mathrm{C_5H_5NC_5H_{11}Br})_2 \cdot \mathrm{MnCl_2}\)

obtained in the same way as the preceding one. To begin crystallization it is necessary to remove almost all the water. The crystals are fairly large, yellow in color, with melting point \(= 272^\circ\).

Extremely readily soluble in water.

Analysis of this complex gave:
1. There is no water of crystallization.
2. Manganese content:

Found . . . . . . . . . . . Mn = 9.46%
Calculated . . . . . . . . Mn = 9.37%

Sample 0.6834 g.
Found Mn\(_3\)O\(_4\) = 0.0899 g.
Mn = 0.06466 g, or 9.46%.

1. Content of chlorine and bromine in the complex:

Found . . . . . . . . . . $\mathrm{Cl}=12.25\%$  $\mathrm{Br}=27.21\%$
Calculated . . . . . . . $\mathrm{Cl}=12.1\%$  $\mathrm{Br}=27.29\%$

Sample $=0.5336$ g.
Weight of $\mathrm{AgCl}+\mathrm{AgBr}=0.6004$ g;
converted to $\mathrm{AgCl}=0.5336$ g.

$\mathrm{AgCl}=0.2668$ g; $\mathrm{Cl}=0.06598$ g, or $12.25\%$.
$\mathrm{AgBr}=0.4336$ g; $\mathrm{Br}=0.1466$ g, or $27.21\%$.

Complex $\mathrm{C_5H_5NC_5H_{11}Br.FeCl_3.H_2O}$

obtained by heating solutions of amylpyridinium bromide (1 mol.) with ferric chloride (1 mol.).

For crystallization to begin, almost complete removal of the water is required. Brown crystals with m.p. $=176.5^\circ$. Very readily soluble in water.

Analysis of the complex gave the following results:

1. Water of crystallization

Found . . . . . . . . . . $4.16\%$
Calculated . . . . . . . $4.38\%$

1. Amount of iron:

Found . . . . . . . . . . $14.07\%$
Calculated . . . . . . . $14.23\%$

Sample $0.5142$ g.
Obtained: $\mathrm{Fe_2O_3}=0.1035$ g.

$\mathrm{Fe}=0.07236$ g, or $14.07\%$.

1. Content of chlorine and bromine in the complex:

Sample $0.5038$ g.
Weight of $\mathrm{AgCl}+\mathrm{AgBr}=0.7940$ g.

Converted to $\mathrm{AgCl}=0.7370$ g.

$\mathrm{AgCl}=0.5526$ g; $\mathrm{Cl}=0.1365$ g.
$\mathrm{AgBr}=0.2414$ g; $\mathrm{Br}=0.1026$ g.

Found . . . $\mathrm{Cl}=27.13\%$  $\mathrm{Br}=20.35\%$
Calculated . . $\mathrm{Cl}=27.11\%$  $\mathrm{Br}=20.37\%$

Complex $(\mathrm{C_5H_5NC_5H_{11}Br})_2.\mathrm{CdJ_2}$

is precipitated in the cold in the form of a white precipitate when solutions of amylpyridinium bromide and cadmium iodide are mixed. The complex is almost insoluble in water. Melting temperature $=260^\circ$.

Analytical data for the complex:

1. There is no water of crystallization.
2. Amount of bromine and iodine:

Found . . . . . . . . . . $\mathrm{Br}=19.04\%$  $\mathrm{J}=31.03\%$
Calculated . . . . . . . $\mathrm{Br}=19.34\%$  $\mathrm{J}=30.71\%$

Sample $0.5834$ g.
Obtained $\mathrm{AgJ}+\mathrm{AgBr}=0.5960$ g.
Converted to $\mathrm{AgCl}=0.4051$ g.

$\mathrm{AgJ}=0.335$ g; $\mathrm{J}=0.1811$ g.
$\mathrm{AgBr}=0.2610$ g; $\mathrm{Br}=0.1111$ g.

1. Cadmium content:

Sample 0.5422 g.
\(\mathrm{CdSO_4}=0.1394\) g.  \(\mathrm{Cd}=0.07516\) g.

Found . . . . . . . . . . . \(\mathrm{Cd}\ 13.55\%\)
Calculated . . . . . . . . . \(13.60\%\)

Complex \((\mathrm{C_5H_5NC_5H_{11}Br})_2\mathrm{CdCl_2}\)

was obtained by the interaction of concentrated solutions of amylpyridinium bromide (2 mol.) and cadmium chloride (1 mol.). Silvery-white scaly crystals precipitate immediately after mixing the aqueous solutions of the starting substances. They are sparingly soluble in water and have m.p. \(=262^\circ\).

Analytical data:
1. No water of crystallization.
2. Cd content in the complex:

Found . . . . . . . . . . . \(17.36\%\)
Calculated . . . . . . . . . \(17.47\%\)

Sample 0.4162 g.
Obtained: \(\mathrm{CdSO_4}=0.1340\) g.; \(\mathrm{Cd}=0.0722\) g.

1. Amount of chlorine and bromine:

Found . . . . . . . \(\mathrm{Cl}=11.10\%\)  \(\mathrm{Br}=24.9\%\)
Calculated . . . . . \(\mathrm{Cl}=11.03\%\)  \(\mathrm{Br}=24.24\%\)

Sample 0.4341 g.
Obtained: \(\mathrm{AgCl}+\mathrm{AgBr}=0.4471\) g.; converted to \(\mathrm{AgCl}=0.3894\) g.
\(\mathrm{AgCl}=0.1947\) g.; \(\mathrm{Cl}=0.0482\) g.;
\(\mathrm{AgBr}=0.2524\) g.; \(\mathrm{Br}=0.1081\) g.
Hence: \(\mathrm{Cl}=11.1\%\); \(\mathrm{Br}=24.90\%\).

II.

Complex compounds of benzylpyridinium chloride with salts of heavy metals.

Benzylpyridinium chloride¹ was obtained by heating equimolecular amounts of freshly distilled pyridine and benzyl chloride to \(100^\circ\). It is a white crystalline substance, extremely readily soluble in water, of bitter taste.

The complex salts obtained from this compound also retain a bitter taste.

Complex \((\mathrm{C_5H_5NCH_2C_6H_5Cl})_2\cdot\mathrm{CuCl_2}\)

was prepared by the interaction of aqueous solutions of benzylpyridinium chloride and cupric chloride, calculated for 2 mol. of the former and 1 mol. of the latter, followed by removal of part of the solvent by heating on a water bath until crystallization began. The crystals are bright orange in color, readily soluble in water, less readily in alcohol, and very little in ether.

The solution is emerald-green in color. M.p. \(144^\circ\).

Analytical data:
1. No water of crystallization.
2. Copper content in the complex:

Found . . . . . . . . . . . \(\mathrm{Cu}=11.91\%\)
Calculated . . . . . . . . . \(\mathrm{Cu}=11.65\%\)

Sample 0.5221 g.
\(\mathrm{Cu_2S}=0.0779\) g.; \(\mathrm{Cu}=0.0622\) g.

1. Chlorine content:

Found: by Volhard’s method . . . 25.62%
by precipitation . . . . . . . . . 25.83%.
Calculated . . . . . . . . . . . . 25.98%

Sample 0.5640 g.
Obtained AgCl = 0.5888 g; Cl = 0.1456 g.
The results of the analysis support the correctness of the formula:

\[ (\mathrm{C_5H_5NCH_2C_6H_5Cl})_2 \cdot \mathrm{CuCl_2}. \]

Complex \((\mathrm{C_5H_5NCH_2C_6H_5Cl})_2 \cdot \mathrm{CuBr_2}\)

was obtained in the same way as the preceding one. The complex is dark brown, almost black in color (dark red as a powder). Melting point = 137.5°. Readily soluble in water. The concentrated solution is brownish in color. Less soluble in alcohol and only slightly soluble in ether.

Analytical data:
1. No water of crystallization.
2. Cu content in the complex:

Obtained . . . . . . . . . . . . 9.98%
Calculated . . . . . . . . . . . 10.02%

Sample 0.5284 g.
Found: Cu₂S = 0.0661 g; Cu = 0.0528 g; Cu = 9.98%.

1. Amount of chlorine and bromine in the complex:

Found . . . . . . . Cl = 11.16%  Br = 25.15%
Calculated . . . . . Cl = 11.18%  Br = 25.21%

Sample 0.6245 g.
Sum AgCl + AgBr = 0.6513 g.
Converted to AgCl = 0.5640 g.
Whence: AgCl = 0.2820 g.  Cl = 0.06974 g.
AgBr = 0.3693 g.  Br = 0.1571 g.

Complex \((\mathrm{C_5H_5NCH_2C_6H_5Cl})_2 \cdot \mathrm{CoCl_2}\)

was obtained by the same method as the preceding one. This compound consists of well-formed crystals of cornflower-blue color, blue as a powder. Readily soluble in water, less so in alcohol, insoluble in ether. Melting point 136°.

Analytical data:
1. No water of crystallization.
2. Cobalt content:

Found . . . . . . . . . . . Co = 10.73%
Calculated . . . . . . . . . Co = 10.9%

Sample 0.6891 g.
Found Co = 0.0739 g.

1. Amount of chlorine in the complex:

Found . . . . . . . . . . . . 26.18%
Calculated . . . . . . . . . . 26.21%

Sample 0.2934 g; AgCl = 0.3040 g; Cl = 0.007508 g, or 26.18%.

Complex of benzylpyridinium chloride with nickel chloride

gives a thick, syrup-like liquid of grass-green color, crystallizing poorly. The small quantity of crystals that could be isolated was bluish-green in color and, in form, close to the form of the crystals of the cobalt complex. m.p. = 142°.

The analysis was not performed, since the substance did not crystallize over the course of 6 months.

The complex of benzylpyridinium chloride with ferric chloride was obtained in two forms: from a boiling mixture of solutions of the starting substances there first separated a powdery precipitate of light-brown color, which was separated by filtration and examined. From the filtrate, after standing for 2 days, there separated prismatic, elongated-habit, transparent crystals of iron-yellow color, which were examined separately.

Analysis of the powdery complex:

1. There is no water of crystallization.
2. Iron content:

\[ \begin{aligned} \text{Found} \ . . . . . . . . . . . .\quad & \mathrm{Fe}=15.62\% \\ \text{Calculated} \ . . . . . . . . .\quad & \mathrm{Fe}=15.18\% \end{aligned} \]

Sample weight: 0.6466 g.
Found: \(\mathrm{Fe_2O_3}=0.1444\) g; \(\mathrm{Fe}=0.10096\) g, or \(15.62\%\).

1. Chlorine content in the complex:

\[ \begin{aligned} \text{Found} \ . . . . . . . . . . . .\quad & \mathrm{Cl}=38.61\% \\ \text{Calculated} \ . . . . . . . . .\quad & \mathrm{Cl}=38.56\% \end{aligned} \]

Sample weight: 0.3542 g.
Obtained: \(\mathrm{AgCl}=0.5542\) g; \(\mathrm{Cl}=0.1368\) g.

From the analytical data it follows that the formula of the brown complex will be:

\[ \mathrm{C_5H_5NCH_2C_6H_5Cl.FeCl_3}. \]

Its melting temperature is \(127.5^\circ\).

Analysis of the iron-yellow complex gave the following results:

1. Water of crystallization: \(4.6\%\).
2. Fe content:

\[ \begin{aligned} \text{Found} \ . . . . . . . . . . . .\quad & \mathrm{Fe}=14.86\% \\ \text{Calculated} \ . . . . . . . . .\quad & \mathrm{Fe}=14.51\% \end{aligned} \]

Sample weight: 0.6020 g.
Found: \(\mathrm{Fe_2O_3}=0.1283\) g; \(\mathrm{Fe}=0.0897\) g, or \(14.86\%\).

1. Amount of chlorine in the complex:

\[ \begin{aligned} \text{Found} \ . . . . . . . . . . . .\quad & \mathrm{Cl}=36.93\% \\ \text{Calculated} \ . . . . . . . . .\quad & \mathrm{Cl}=36.76\% \end{aligned} \]

Sample weight: 0.3490 g.
Obtained: \(\mathrm{AgCl}=0.5210\) g; \(\mathrm{Cl}=0.1288\), or \(36.93\%\).

It follows from this that the formula of the compound studied must be:

\[ \mathrm{C_5H_5NCH_2C_6H_5Cl.FeCl_3.H_2O}. \]

Its melting temperature is \(78^\circ\).

This complex is readily soluble in water, in contrast to the light-brown one, which is less readily soluble.

The complex \((\mathrm{C_5H_5NCH_2C_6H_5Cl})_2.\mathrm{MnCl_2}\)

was obtained by the same method as all the preceding ones. Well-formed light-yellow crystals begin to separate from the solution only when almost all the water has evaporated. Melting temperature \(=123.5^\circ\).

Analysis data:

1. There is no water of crystallization.
2. Mn content:

Found . . . . . . . . . . . . . . . . . $\mathrm{Mn}=10.54\%$
Calculated . . . . . . . . . . . . $\mathrm{Mn}=10.23\%$

Sample 0.4872 g.
Found: $\mathrm{Mn_3O_4}=0.0714$ g; $\mathrm{Mn}=0.0514$ g.

1. Amount of chlorine in the complex:

Found . . . . . . . . . . . . . . . . . $26.59\%$
Calculated . . . . . . . . . . . . $26.4\%$

Sample 0.4132 g.
Found: $\mathrm{AgCl}=0.4441$ g; $\mathrm{Cl}=0.1098$ g, or $26.59\%$.

Complex $(\mathrm{C_5H_5NCH_2C_6H_5Cl})_2 \cdot \mathrm{CdCl_2}$.

When aqueous solutions of benzylpyridinium chloride and cadmium chloride are mixed, a white precipitate immediately separates, which indicates the lower solubility of the cadmium complex than of the other compounds considered above. Its m.p. is $134^\circ$.

Analysis data:

1. There is no water of crystallization.
2. Cd content:

Found . . . . . . . . . . . . . . . . . $\mathrm{Cd}=18.93\%$
Calculated . . . . . . . . . . . . $\mathrm{Cd}=18.90\%$

Sample 0.6381 g.
Obtained: $\mathrm{CdSO_4}=0.2235$ g; $\mathrm{Cd}=0.1205$ g, or $18.93\%$.

In an attempt to obtain the complex of benzylpyridinium chloride with cadmium iodide, a heavy oil separated, which then changed into yellowish crystals, extremely difficultly soluble in water. On prolonged boiling the substance passes into solution, from which, on cooling, yellowish, scaly, lustrous, small plates crystallize, with m.p. $=155^\circ$.

According to the analytical data, it proved to be benzylpyridinium iodide, which gives white complex compounds both with cadmium iodide and with cadmium chloride.

The latter were not investigated.

Experiments to obtain complexes of another composition by the indicated method of work gave a negative result.

Complex compounds with sulfuric-acid and nitric-acid salts of heavy metals could not be prepared. On evaporating a mixture of solutions of benzylpyridinium chloride and the sulfate of one or another metal, the greater part of the sulfate precipitates; a small part enters into a double-decomposition reaction with tetra-substituted ammonium. The metal chloride thereby formed gives a complex with benzylpyridinium chloride, i.e., one or another of the already studied compounds is obtained. This is easy to conclude by comparing the form, color, and m.p. of the crystals obtained with the corresponding complex prepared with the chloride of the given metal.

Thus it may be assumed that the reaction proceeds as follows:

I. $2\mathrm{C_5H_5NCH_2C_6H_5Cl}+\mathrm{CoSO_4}\rightleftarrows(\mathrm{C_5H_5NCH_2C_6H_5})_2\mathrm{SO_4}+\mathrm{CoCl_2}$.

II. $2\mathrm{C_5H_5NCH_2C_6H_5Cl}+\mathrm{CoCl_2}=(\mathrm{C_5H_5NCH_2C_6H_5Cl})_2\mathrm{CoCl_2}$.

Residue after separation of the crystals:

1. \( \mathrm{CoSO_4 \cdot 7H_2O} \), flesh-red in color,
2. \( (\mathrm{C_6H_5NCH_2C_6H_5Cl})_2 \cdot \mathrm{CoCl_2} \), blue in color; it is a thick, yellowish liquid, which did not crystallize over the course of 6 months.

Conclusions.

1. The results of the present work show that pyridinium salts, like quinolinium salts, can also give complex compounds with halides of heavy metals. It may be supposed that this capacity is inherent in general in all, or at any rate in many, organic ammonium salts.

2. The very low solubility of some of the complexes obtained supports the idea of the possibility of using tetrasubstituted ammonium salts as characteristic reagents for the corresponding metals. Of the complex salts studied in the present work, the following proved to be sparingly soluble:

\[ (\mathrm{C_5H_5NC_5H_{11}Br})_2 \cdot \mathrm{CdCl_2}, \]

\[ (\mathrm{C_5H_5NC_5H_{11}Br})_2 \cdot \mathrm{CdJ_2}. \]

It is possible that the use of one of these compounds will be of benefit in the determination of cadmium.

1. Hofmann. B. 14, 1505. ↩↩↩