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Hydrazine complexes of copper(I) chloride
Notes
3 313
63.0 °, the latent heat of vaporisation as 7.80 kcal.mole -1, and Trouton constant as 23.0. The chief i.r. bands were 1400 w, 1180 vs, 1140 w, 840 s, 760 w, 610 s, 570 s, 530 m, and 440 cm -1. Reaction of bis(trifluoromethyl)amino-bis(trifluoromethyl)arsine with chlorine. Reaction of bis (trifluoromethyl)amino-bis(trifluoromethyl)-arsine (11 I) (1.64 g, 4.48 m-moles) with chlorine (0.568 g, 8.01 m-mole) at 20° (14 hr) gave bis(trifluoromethyl)amino-dichloroarsine (1.37 g, 4"0 m-moles) (Found: CI, 23.2%; C2F6CI~AsN requires CI, 23.8%). The vapour pressures can be represented by the equation, log10 Prom = 7.450 - 2066/T, giving the extrapolated boiling point as 98.0 °, the heat of vaporisation as 9.46 kcal.mole -1 and Trouton constant as 25. The chief i.r. bands were found at 1325 vs, 1130 vs, 1260 vs, 1205 vs, 973 m, 705 w cm -1. The other products found in this reaction were trifluoromethyl chloride (0.867 g, 8.29 m-moles) and N-chlorobis(trifluoromethyl)amine (0.018 g, 0.098 m-mole). In another experiment, the amino-arsine (lI1) (0.632 g, 1.734 m-moles) was again allowed to react with chlorine (0.331 g, 4"67 m-moles) at room temperature for two days. Fractionation of the products gave arsenic trichloride (0.353g, 1-95 m-moles) (Found: CI, 58 2%; M, 181; AsCI3 requires: Cl, 58.7%, M, 182), trifluoromethyl chloride (0"367 g, 3"51 m-moles), and N-chlorobis(trifluoromethyl)amine (0.28 g, 1'58 m-moles) and unreacted amino-arsine (Ili)(0.0199 g, 0-0545 m-moles).
Acknowledgements-The author thanks Professor H. J. Emeleus, F.R.S., for advice and encouragement, and the Royal Commission for the Exhibition of 1851 for a scholarship while this work was being undertaken.
Department of Chemistry University of Singapore Singapore
H. G. A N G
J. inorg,nucl.Chem., 1969,Vol.31, pp. 3313to 3315. PergamonPress. Printedin Great Britain
Hydrazine complexes of copper(I) chloride (Received 24 January 1969) BIS(HYDRAZINE) complexes M (N2H4)2Ci 2 ~ = Mn, Fe, Co, Ni, Zn and Cd) are well characterised [ 13] reaction products of the divalent metal chlorides with hydrazine in aqueous solution. The copper(I I) complex however is particularly difficult to isolate from aqueous solution because of its ease of reduction; indeed the oxidation of hydrazine by aqueous copper(I1) salts has been known for many years as an analytical method[l]. Copper(l) complexes of hydrazines have not been reported; the aqueous reactions resulting usually in the formation of copper(I) oxide. We report here some non-aqueous reactions of copper chlorides with hydrazine and methylhydrazines.
RESULTS AND DISCUSSION Anhydrous hydrazine reduces copper(ll) chloride, the white reaction product of composition CuCI~.3N2H4 being a mixture of NeH4.HCI and CuCI.2N2H4. The overall stoichlometry is probably represented by: 2CUC12 + 8N2H4 --* 2Cu(N2H4)C! + 2N2H4.HCI + 2 N H 3 + N2. 1. L. F. Audrieth and B. A. Ogg, The Chemistry of Hydrazine. Wiley, New York (195 !). 2. L. Sacconi and A. Sabatini, J. inorg, nucl. Chem. 25, 1389 (1963). 3. D. Nicholls and R. Swindells, J. inorg, nucl. Chem. 30, 2211 (1968).
3314
Notes
This bis(hydrazine)copperfl) chloride is readily prepared pure by direct reaction between anhydrous hydrazine and copper(l) chloride. It is a 1 : 1 electrolyte in hydrazine so that in solution at least it is best formulated as a linear cationic complex [N2H~ --~ Cu ,--- N~H4]+C1-. When heated in vacua at 80 ° some reduction to copper occurs according to 2Cu(N2H4)2CI ---> 2 C u + 2N2H4-HCI + 2 N H 3 + N2. The aqueous reactions between copper(II) chloride and methylhydrazines result in evolution of nitrogen and reduction of the copper(II) to copper(l) oxide. Under anhydrous conditions, 1,1-dimethylhydrazine (DMH) reduces copper(II) chloride to a copper(I) complex but the complex cannot readily be isolated from this system. Copper(I) chloride forms a series of complexes with D M H (Fig. 1), the
30
E E
I0
1.0
2!0
Mote ratio Me2 NNHz/CuCI
Fig. 1. Tensimetric study of the CuC1-DMH system at 21°C. thermally stable phase at 21 °C being (CuCI)2 DMH. The other phases correspond to CuC1-DMH and CuCI.2DMH; the extra dimethylhydrazine in these complexes is probably not coordinated but held rather by a weaker type of interaction. The direct reaction between copper(l) chloride and monomethylhydrazine (MMH) leads to some reduction to metallic copper and a pure complex could not be isolated in this reaction. Using dilute alcoholic solutions of copper(II) chloride and M M H however, white crystals of (CuCI)2 M M H can be isolated. This compound is insoluble in non-polar solvents. In methyl cyanide it gives a molar conductivity well below that expected for 1 : 1 electrolytes; reaction with the solvent is probably occurring to some extent to give CuCI.MeCN which is known to be a 1 : 1 electrolyte in methyl cyanide[4]. The complexes (CuCI)2 D M H and (CuCI)2 M M H are probably polymeric with bridging hydrazines although a simple monomeric structure e.g., CI-Cu-NMe2NH2Cu-C1 cannot be ruled out. It is interesting to note that azomethane, another N - N bonded ligand, also forms a complex of stoichiometry (CuCI)~.L and the crystal structure of this complex has been shown [5] to possess infinite Cu-CI chains linked by bridging azomethane molecules. 4. B.J. Hathaway, D. G. Holah andJ. D. Postlethwaite, J. chem. Sac. 3215 (1961). 5. I. D. Brown andJ. D. Dunitz, Acta CrystaUogr. 13, 28 (1960).
Notes
33 ! 5
EXPERIMENTAL Experimental methods and materials. Hydrazines were purified as described previously[6]. Chloride was determined gravimetrically as silver chloride after removal of hydrazines with nitrous acid; copper by thiosulphate titration after oxidation of copper(I) to copper(II) by hydrogen peroxide and destruction of excess peroxide by boiling. Infrared spectra were measured on a Grubb-Parsons G.S.2A instrument and magnetic moments were by the Gouy method. Tensimetric studies were carried out as previously described[3] and all reactions were performed in the absence of air, usually in vacuum apparatus. Reactions with hydrazine-(1) copper(ll) chloride. An excess of anhydrous hydrazine (10 cm 3) was condensed on to anhydrous copper(lI) chloride (0" 1527 g) in vacuo a t - 196°C and the mixture allowed to warm to room temperature. As the hydrazine melted, a vigorous reaction occurred, the crystals turned white and dissolved in the excess of hydrazine. Nitrogen was evolved together with ammonia, these were identified by i.r. and vapour density measurements after fractionation of the volatile constituents. When all the volatiles had been removed in vacuo a white solid (0.2641 g; CuCI~ : N2H4 = 1:3.06) remained. This solid was diamagnetic and its i.r. spectrum showed it to contain N2Ha'HCI and have a peak at 959 cm -1 which we assign to v(N-N) in Cu(N2H4)2CI. It was partly soluble in water giving a colourless solution. (2) Copper(l) chloride. When copper(I) chloride (0.2302 g) was reacted with an excess of hydrazine, a smooth reaction occurred and the chloride partly dissolved. Removal of all the excess hydrazine in vacuo gave 0.3790 g of a white, diamagnetic, residue (Found, Cu, 39.1; C1, 21.7%; CufN2H4)2CI requires, Cu, 38-95; CI, 21.74%). The molar conductivity of a 10-3 M solution of Cu(N2H4)2CI in hydrazine was 76 ohm -1 cm2; at the same concentration Et4NI has AM = 77 ohm -~ cm 2 and Ba(NOz)2 has A~ = 145 ohm -~ cm 2. When heated in vacuo Cu(N2H4)~CI began to evolve hydrazine at 40° and at 80° decomposition occurred to give a red-brown residue and ammonia and nitrogen were evolved. The i.r. spectrum of the residue showed the presence of N 2H4'HC1. Reactions with l,l-dimethylhydrazine-(l) copper(ll) chloride. When an excess of DMH was condensed upon copper(lI) chloride, a dark brown solution was formed; this solution became paler as ammonia and nitrogen were evolved. After removal of all volatiles a pale yellow viscous oil remained with overall composition varying between CuC12.0.95 DMH and CuCI2.1.19DMH in different experiments. Because a powdered sample of the product could not be obtained, the magn,,-tic moment was determined in DMH solution and the complex found to be diamagnetic. The i.r. spectrum of the viscous oil was very complex but contained all the absorptions present in Me2NHNH2CI. The oil was extremely sensitive to air, the surface darkening immediately. (2) Copper(l) chloride. The reaction of copper(I) chloride (0.5680 g) with an excess of DMH followed by removal of the excess in vacuo gave a diamagnetic white powder (0-7442 g) (Found, Cu, 49.1; CI, 27.3%; (CuCI)2 DMH requires Cu, 49.23; Ci, 27.47%). A tensimetric study of the CuCID M H system was carried out at 21 °, the solid-vapour equilibrium part of the diagram being shown in Fig. 1. Reaction o f copper(li) chloride with monomethylhydrazine. A solution of MMH (1 cm a) in absolute ethanol (300 cm z) was added dropwise, with stirring, to a solution of hydrated copper(lI) chloride (2 g) in absolute ethanol (200 cmZ). The blue copper(ll) solution effervesced and became colourless; when the solution was colourless it was set aside; white crystals slowly deposited. These were filtered off, washed with ethanol, ether, and dried in vacuo; (Found, Cu, 52"3; CI, 28-9%; (CuCI)2 MMH requires Cu, 52.08; Ci, 29.06%). The use of more concentrated solutions of the reagents (or if excess MMH is added) results in the formation of a light brown oily precipitate which we have not characterised. If the white crystals of Cu(NsH4)~C! are allowed to stand in contact with mother liquor for a few days or the crystallization allowed to occur in sunlight, they become coated with red copper metal. The complex is insoluble in benzene and ethylene dichloride, sparingly soluble in nitromethane and soluble in methyl cyanide (Au at 10 -z M = 71 ohm -~ cm2; Au for 1 : 1 electrolytes are of the order [7] of 159 ohm -t cm2); it is hydrolysed by caustic soda to copper(I) oxide with liberation of MMH. Donnan Laboratories University o f Liverpool England
D. N I C H O L L S R. S W l N D E L L S
6. D. Nicholls and R. Swindells, J. chem. Soc. 4204 (1964). 7. M.W. Duckworth, G. W. A. Fowles and R. A. Hoodless,J. chem. Soc. 5665 (1963).
3 313
63.0 °, the latent heat of vaporisation as 7.80 kcal.mole -1, and Trouton constant as 23.0. The chief i.r. bands were 1400 w, 1180 vs, 1140 w, 840 s, 760 w, 610 s, 570 s, 530 m, and 440 cm -1. Reaction of bis(trifluoromethyl)amino-bis(trifluoromethyl)arsine with chlorine. Reaction of bis (trifluoromethyl)amino-bis(trifluoromethyl)-arsine (11 I) (1.64 g, 4.48 m-moles) with chlorine (0.568 g, 8.01 m-mole) at 20° (14 hr) gave bis(trifluoromethyl)amino-dichloroarsine (1.37 g, 4"0 m-moles) (Found: CI, 23.2%; C2F6CI~AsN requires CI, 23.8%). The vapour pressures can be represented by the equation, log10 Prom = 7.450 - 2066/T, giving the extrapolated boiling point as 98.0 °, the heat of vaporisation as 9.46 kcal.mole -1 and Trouton constant as 25. The chief i.r. bands were found at 1325 vs, 1130 vs, 1260 vs, 1205 vs, 973 m, 705 w cm -1. The other products found in this reaction were trifluoromethyl chloride (0.867 g, 8.29 m-moles) and N-chlorobis(trifluoromethyl)amine (0.018 g, 0.098 m-mole). In another experiment, the amino-arsine (lI1) (0.632 g, 1.734 m-moles) was again allowed to react with chlorine (0.331 g, 4"67 m-moles) at room temperature for two days. Fractionation of the products gave arsenic trichloride (0.353g, 1-95 m-moles) (Found: CI, 58 2%; M, 181; AsCI3 requires: Cl, 58.7%, M, 182), trifluoromethyl chloride (0"367 g, 3"51 m-moles), and N-chlorobis(trifluoromethyl)amine (0.28 g, 1'58 m-moles) and unreacted amino-arsine (Ili)(0.0199 g, 0-0545 m-moles).
Acknowledgements-The author thanks Professor H. J. Emeleus, F.R.S., for advice and encouragement, and the Royal Commission for the Exhibition of 1851 for a scholarship while this work was being undertaken.
Department of Chemistry University of Singapore Singapore
H. G. A N G
J. inorg,nucl.Chem., 1969,Vol.31, pp. 3313to 3315. PergamonPress. Printedin Great Britain
Hydrazine complexes of copper(I) chloride (Received 24 January 1969) BIS(HYDRAZINE) complexes M (N2H4)2Ci 2 ~ = Mn, Fe, Co, Ni, Zn and Cd) are well characterised [ 13] reaction products of the divalent metal chlorides with hydrazine in aqueous solution. The copper(I I) complex however is particularly difficult to isolate from aqueous solution because of its ease of reduction; indeed the oxidation of hydrazine by aqueous copper(I1) salts has been known for many years as an analytical method[l]. Copper(l) complexes of hydrazines have not been reported; the aqueous reactions resulting usually in the formation of copper(I) oxide. We report here some non-aqueous reactions of copper chlorides with hydrazine and methylhydrazines.
RESULTS AND DISCUSSION Anhydrous hydrazine reduces copper(ll) chloride, the white reaction product of composition CuCI~.3N2H4 being a mixture of NeH4.HCI and CuCI.2N2H4. The overall stoichlometry is probably represented by: 2CUC12 + 8N2H4 --* 2Cu(N2H4)C! + 2N2H4.HCI + 2 N H 3 + N2. 1. L. F. Audrieth and B. A. Ogg, The Chemistry of Hydrazine. Wiley, New York (195 !). 2. L. Sacconi and A. Sabatini, J. inorg, nucl. Chem. 25, 1389 (1963). 3. D. Nicholls and R. Swindells, J. inorg, nucl. Chem. 30, 2211 (1968).
3314
Notes
This bis(hydrazine)copperfl) chloride is readily prepared pure by direct reaction between anhydrous hydrazine and copper(l) chloride. It is a 1 : 1 electrolyte in hydrazine so that in solution at least it is best formulated as a linear cationic complex [N2H~ --~ Cu ,--- N~H4]+C1-. When heated in vacua at 80 ° some reduction to copper occurs according to 2Cu(N2H4)2CI ---> 2 C u + 2N2H4-HCI + 2 N H 3 + N2. The aqueous reactions between copper(II) chloride and methylhydrazines result in evolution of nitrogen and reduction of the copper(II) to copper(l) oxide. Under anhydrous conditions, 1,1-dimethylhydrazine (DMH) reduces copper(II) chloride to a copper(I) complex but the complex cannot readily be isolated from this system. Copper(I) chloride forms a series of complexes with D M H (Fig. 1), the
30
E E
I0
1.0
2!0
Mote ratio Me2 NNHz/CuCI
Fig. 1. Tensimetric study of the CuC1-DMH system at 21°C. thermally stable phase at 21 °C being (CuCI)2 DMH. The other phases correspond to CuC1-DMH and CuCI.2DMH; the extra dimethylhydrazine in these complexes is probably not coordinated but held rather by a weaker type of interaction. The direct reaction between copper(l) chloride and monomethylhydrazine (MMH) leads to some reduction to metallic copper and a pure complex could not be isolated in this reaction. Using dilute alcoholic solutions of copper(II) chloride and M M H however, white crystals of (CuCI)2 M M H can be isolated. This compound is insoluble in non-polar solvents. In methyl cyanide it gives a molar conductivity well below that expected for 1 : 1 electrolytes; reaction with the solvent is probably occurring to some extent to give CuCI.MeCN which is known to be a 1 : 1 electrolyte in methyl cyanide[4]. The complexes (CuCI)2 D M H and (CuCI)2 M M H are probably polymeric with bridging hydrazines although a simple monomeric structure e.g., CI-Cu-NMe2NH2Cu-C1 cannot be ruled out. It is interesting to note that azomethane, another N - N bonded ligand, also forms a complex of stoichiometry (CuCI)~.L and the crystal structure of this complex has been shown [5] to possess infinite Cu-CI chains linked by bridging azomethane molecules. 4. B.J. Hathaway, D. G. Holah andJ. D. Postlethwaite, J. chem. Sac. 3215 (1961). 5. I. D. Brown andJ. D. Dunitz, Acta CrystaUogr. 13, 28 (1960).
Notes
33 ! 5
EXPERIMENTAL Experimental methods and materials. Hydrazines were purified as described previously[6]. Chloride was determined gravimetrically as silver chloride after removal of hydrazines with nitrous acid; copper by thiosulphate titration after oxidation of copper(I) to copper(II) by hydrogen peroxide and destruction of excess peroxide by boiling. Infrared spectra were measured on a Grubb-Parsons G.S.2A instrument and magnetic moments were by the Gouy method. Tensimetric studies were carried out as previously described[3] and all reactions were performed in the absence of air, usually in vacuum apparatus. Reactions with hydrazine-(1) copper(ll) chloride. An excess of anhydrous hydrazine (10 cm 3) was condensed on to anhydrous copper(lI) chloride (0" 1527 g) in vacuo a t - 196°C and the mixture allowed to warm to room temperature. As the hydrazine melted, a vigorous reaction occurred, the crystals turned white and dissolved in the excess of hydrazine. Nitrogen was evolved together with ammonia, these were identified by i.r. and vapour density measurements after fractionation of the volatile constituents. When all the volatiles had been removed in vacuo a white solid (0.2641 g; CuCI~ : N2H4 = 1:3.06) remained. This solid was diamagnetic and its i.r. spectrum showed it to contain N2Ha'HCI and have a peak at 959 cm -1 which we assign to v(N-N) in Cu(N2H4)2CI. It was partly soluble in water giving a colourless solution. (2) Copper(l) chloride. When copper(I) chloride (0.2302 g) was reacted with an excess of hydrazine, a smooth reaction occurred and the chloride partly dissolved. Removal of all the excess hydrazine in vacuo gave 0.3790 g of a white, diamagnetic, residue (Found, Cu, 39.1; C1, 21.7%; CufN2H4)2CI requires, Cu, 38-95; CI, 21.74%). The molar conductivity of a 10-3 M solution of Cu(N2H4)2CI in hydrazine was 76 ohm -1 cm2; at the same concentration Et4NI has AM = 77 ohm -~ cm 2 and Ba(NOz)2 has A~ = 145 ohm -~ cm 2. When heated in vacuo Cu(N2H4)~CI began to evolve hydrazine at 40° and at 80° decomposition occurred to give a red-brown residue and ammonia and nitrogen were evolved. The i.r. spectrum of the residue showed the presence of N 2H4'HC1. Reactions with l,l-dimethylhydrazine-(l) copper(ll) chloride. When an excess of DMH was condensed upon copper(lI) chloride, a dark brown solution was formed; this solution became paler as ammonia and nitrogen were evolved. After removal of all volatiles a pale yellow viscous oil remained with overall composition varying between CuC12.0.95 DMH and CuCI2.1.19DMH in different experiments. Because a powdered sample of the product could not be obtained, the magn,,-tic moment was determined in DMH solution and the complex found to be diamagnetic. The i.r. spectrum of the viscous oil was very complex but contained all the absorptions present in Me2NHNH2CI. The oil was extremely sensitive to air, the surface darkening immediately. (2) Copper(l) chloride. The reaction of copper(I) chloride (0.5680 g) with an excess of DMH followed by removal of the excess in vacuo gave a diamagnetic white powder (0-7442 g) (Found, Cu, 49.1; CI, 27.3%; (CuCI)2 DMH requires Cu, 49.23; Ci, 27.47%). A tensimetric study of the CuCID M H system was carried out at 21 °, the solid-vapour equilibrium part of the diagram being shown in Fig. 1. Reaction o f copper(li) chloride with monomethylhydrazine. A solution of MMH (1 cm a) in absolute ethanol (300 cm z) was added dropwise, with stirring, to a solution of hydrated copper(lI) chloride (2 g) in absolute ethanol (200 cmZ). The blue copper(ll) solution effervesced and became colourless; when the solution was colourless it was set aside; white crystals slowly deposited. These were filtered off, washed with ethanol, ether, and dried in vacuo; (Found, Cu, 52"3; CI, 28-9%; (CuCI)2 MMH requires Cu, 52.08; Ci, 29.06%). The use of more concentrated solutions of the reagents (or if excess MMH is added) results in the formation of a light brown oily precipitate which we have not characterised. If the white crystals of Cu(NsH4)~C! are allowed to stand in contact with mother liquor for a few days or the crystallization allowed to occur in sunlight, they become coated with red copper metal. The complex is insoluble in benzene and ethylene dichloride, sparingly soluble in nitromethane and soluble in methyl cyanide (Au at 10 -z M = 71 ohm -~ cm2; Au for 1 : 1 electrolytes are of the order [7] of 159 ohm -t cm2); it is hydrolysed by caustic soda to copper(I) oxide with liberation of MMH. Donnan Laboratories University o f Liverpool England
D. N I C H O L L S R. S W l N D E L L S
6. D. Nicholls and R. Swindells, J. chem. Soc. 4204 (1964). 7. M.W. Duckworth, G. W. A. Fowles and R. A. Hoodless,J. chem. Soc. 5665 (1963).