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Diacetylazine-dioximato metal chelates of Cu(II) and Ni(II); Their i.r. spectra and magnetic properties
J. inorg,nucl.Chem.,197I, Vol.33, pp. 1313to 1317. PergamonPress. Printedin Great Britain
DIACETYLAZINE-DIOXIMATO METAL CHELATES Cu(II) AND Ni(II); THEIR I.R. SPECTRA AND MAGNETIC PROPERTIES
OF
S. SATPATHY and B. SAHOO Indian Institute of Technology, Kharagpur-2, West Bengal, India
(Received 28 September 1970)
Abstract-Diacetylazine-dioxime and its Cu(II) and Ni(II) complexes have been prepared. Assignments of i.r. bands have been made for N - O - H bending, C - - N (azine), ~ N (oxime) and N - O stretching mode. The spectra evince that diacetylazine-dioximate ion is bonded to Cu(II) and Ni(II) in a bi-bidentate manner. Magnetic susceptibility values over a range of temperature show the presence of antiferromagnetic exchange interaction in these systems. INTRODUCTION
Irq Arq earlier paper[l] it was shown that salicylaldazinate ion acts as a dichelating agent with Cu(II), Ni(II) and Co(II), and functions as a tridentate chelating agent with Fe(II). In order to further know the manner in which tetrafunctional azine ligands are coordinated and the properties of such complexes, studies have been carried out with a new azine ligand, diacetylazine-dioxime, CsHI~N40~H2, (abbreviated as DAADOH2). Its Cu(II) and Ni(II) complexes are reported here. Their i.r. spectra indicate that D A A D O forms dichelate complexes with Cu(II) and Ni(II) and the magnetic susceptibilities of the complexes over a range of temperature show the presence of antiferromagnetic exchange interaction in these systems. RESULTS AND DISCUSSION
I.R. spectra
The important vibrational bands of the ligand and the metal complexes are given in Table 1. The most probable structure of D A A D O H ~ is illustrated in Fig. 1. The i.r. spectra of the ligand show multiple bands in the region 3300-2700 cm -1 indicating strong hydrogen bonding in the ligand involving N - O - H group. Further, they are in coincidence with C - H stretching vibrations. The O H stretching vibrations of several oximes involving intramolecular or intermolecular hydrogen bonding are found to occur in 3250-2350 cm -1 region [2,3].
:-%_:-% \O--H"
"H--O/
Fig. 1. 1. S. Satapathy and B. Sahoo, J. inorg, nucl. Chem. 32, 2223 (1970). 2. A. Palm and H. Werbin, Can. J. Chem. 31, 1004 (1953). 3. R. Blinc and D. Hadzi, J. chem. Soe. 4536 (1958). 1313
1314
S. S A T P A T H Y
and B. S A H O O
Table I. Principal i.r. absorption bands for biacetylazinedioxime and its copper(II) and nickel(II) complexes (frequencies in c m -~)
Cu(CsH12N402)
Ni(CsH12N402) 2H20
3125 s (bd) 2849 sh 1672 s
3279 s 2778 w
3226 s (bd)~ 2778 w J
1595 1429 1351 1121 1024 970 930 780 758
1587 1481 1370 1205 1104 1010 990 828 758
1613 1563 1471 1353 1178 1087 I010 980 766 741
CsH~2N402H2
s m s s s s s s m (bd)
m ms s ms s m m s m (bd)
m m s ms ms s w ms w / m (bd)
1
Tentative band assignments
O - H and C - H stretch O - H deformation of N O H group H 2 0 deformation ~N stretch ~N stretch CH3 deformation CH3 rock N-Ostretch
CH~ deformation vibrations
s = strong; m = m e d i u m ; w = weak; m s = m e d i u m strong; bd = broad; sh = shoulder.
A salient feature of the spectra of the ligand is a strong and sharp band at 1672 cm -1 which has been assigned to O - H deformation vibration of the N O H group. This assignment is further strengthened since this band does not occur in the metal complexes where the O - H bonds have been broken in the formation of the metal complexes. I.R. spectra of metal complexes with dimethylglyoximeand with cyclohexane 1:2 dione dioxime show the presence of O - H deformation vibration in the region 1650-1820 cm -1 [3]. The spectra of the ligand as well as metal complexes have certain features in the region 1600-900 cm -1 which are particularly useful as evidence of structure. The first band in this region in the ligand and its metal complexes is found in the region 1600-1560 cm -1 which has been attributed to the ~ N stretching vibration of the azine group. In the spectra of azines and their metal complexes this band appears between 1670-1527 cm -~ [1,4-6]. The next band appears in the region ~ 1485-1430 cm -1 and has been tentatively assigned to ~ N stretching vibration of the ~ N O H group. The unusually lower value of the ~ N group possibly arises due to high degree of conjugation in the ligand. The above assignment is further based on the findings of several earlier workers. In simple oximes [2], the ~ N band appears in the region 16601618 cm -~. In quinoneoximes [7] this band appears at smaller wave numbers (1570-1520 cm -j) which are explained in terms of a strong conjugation with the quinonoid double bonds. Similarly in 2-pyridine aldoxime [8] and in its uncharged metal complexes the ~ N band (acyclic) has been found in 1519-1505 cm-L In 4. 5. 6. 7. 8.
W . J . Stratton and D. H. Busch, J..4 m. chem. Soc. 82, 4834 (1960). R. G. R. Bacon and W. S. Lindsay, J. chem. Soc. 1382 (1958). W . J . Stratton, J. Inorg. Chem. 9, 517 (1970). D. Hadzi, J. chem. Soc. 2725 (1956). R . A . K r a u s e , N. B. Colthup and D. H. Busch, J. phys. Chem. 65, 2216 ( 1961).
Diacetylazine-dioximato metal complexes
1315
dimethyl glyoxime the first band, which is probably the ~ N band appears [9] at 1450 cm -1 and in its metal complexes the ~ N band is located in the region 1560-1490 cm -1 [3]. Our next attempt was to look for the N - O stretching absorption band. Usually, for simple oximes [ 10], N - O stretching bands appear between 960-930 cm -~ and for quinoneoximes[7] near 1000cm -~. In dimethylglyoxime[3] and its metal chelates a couple of bands are located in the region 1250-900 cm-' and has been attributed to N - O stretching vibration. In pyridine aldoxime [8] the band is found at 982 cm -~ but in its metal chelates a group of three bands are observed in the region 1200-950 cm -1. Since it was not possible in the latter case to make an unambiguous assignment to these bands, the band in the middle of the group was arbitrarily chosen as representing the N - O band. In the present case a group of three bands are observed in the region 1100-900 cm-' in the ligand as well as in its metal complexes- a situation analogous to that of pyridine aldoximato metal complexes. It is difficult to make an unequivocal assignment to these bands and in view of this, the band in the middle of the group has been chosen as the N - O stretching band. This band is generally situated at a relatively higher frequency region as expected. As can be seen from the spectral data, the bands for C : N and N - O groups do not split. Besides, there is one to one correspondence for all other bands in the ligand and in its metal complexes in the region 1600-900 cm-L The above spectral data provide the logical conclusion relating to the structure of the complexes, i.e. symmetric bi-bidentate bonding of the ligand with Cu(II) and Ni(II); and the most probable structures of the complexes may be represented as shown in Fig. 2. CH3 CH3 CHs CH3 \ / \ /
O
~ 2
Fig. 2.
M 2
O
M 2+ = Cu 2+, Ni 2+.
Magnetic susceptibility Magnetic properties of the compounds have been studied over the temperature range 90°K to 300°K. Replicate determinations have been carded out on separately prepared samples. The resultant susceptibilities, (XM), were corrected for diamagnetism[11] and temperature independent paramagnetism (t.i.p.). The t.i.p. values 60 x 10-~ c.g.s., e.m.u, and 240 x 10-e c.g.s., e.m.u, were used for Cu(II)[12] and Ni(II)[13] ion respectively. The effective magnetic moment,/ze,, has been calculated at each temperature employing the expression /Zerf=2"83 (x~T) +in 9. K. Nakamoto, I.R. Spectra of Inorganic and Co-ordination Compounds p. 195. Wiley, New York 1963. 10. A. Palm and H. Werbin, Can.J. Chem. 32,858 (1954). 11. B. N. Figgis and J. Lewis, In Modern Coordination Chemistry (Edited by J. Lewis and R. G. Wilkins), p. 403. Interscience, New York (1960). 12. B.N. Figgis and R. L. Martin, J. chem. Soc. 3837 (1956). 13. B.N. Figgis, Introduction to Ligand Fields Chap. 10. Interscience, New York.
1316
S. S A T P A T H Y and B. S A H O O
(Table 2). Graphs of 1/X'~ against temperature gave straight lines for both the compounds and both yielded negative values of 0 . - 160°K a n d - 149°K for Cu(II) and Ni(II) complexes respectively. The presence of antiferromagnetic exchange interaction is clearly implied by the decrease in magnetic moment per nickel ion from 2-67 B.M. at 304°K to 1.99 B.M. at 87°K and per copper(II) ion from 1.17 B.M. at 303°K to 0.87 B.M. at 91°K respectively and from their respective negative Weiss constants. The most obvious fact about these complexes is that the metal ions are bridged by a conjugated system. Among polynuclear complexes, where metal ions are bridged by a conjugated system, superexchange interactions have been studied only in few cases. Ball et al.[14,15] have for the first time and only recently reported spin-spin interaction between two Ni 2+ ions and two Co z+ ions bridged by some dichelating agents containing conjugated systems. Table 2. Magnetic susceptibilities, X~, (c.g.s., e.m.u., after correction for t.i.p, and diamagnetism as described in the text) per formula weight as indicated Cu(CsH12N40~) : 0 = - 160°K 252 237 210 641 665 707 1"13 1"12 1.09
T(°K) 106 x X~ /~en(B.M.)
303 568 1"17
273 607 1"15
195 747 1"08
165 812 1"03
129 913 0"97
T(°K) 106 x X~ /~e~ (B.M.)
304 2941 2"67
Ni(CaHI~N402) 2H20 : 0 = - 149°K 259 240 224 205 183 3321 3436 3596 3783 4011 2"62 2"57 2"54 2"49 2"42
108 5160 2" 11
87 5712 1"99
91 1062 0"87
EXPERIMENTAL Apparatus. Magnetic susceptibilities were measured by the Guoy method with Hg[Co(CNS)4] as calibrant[16]. Current through the magnet was maintained by a stabilised power supply (supplied by Toshniwal & Co., India). The temperature was controlled by a liquid air cryostat and measured with a copper constantan thermocouple. The measured susceptibility of Cu(CHaCO2)2H20 agreed satisfactorily over the range of 80°-300°K [ 12]. I.R. spectra were taken by Perkin Elmer i.r. spectrophotometer in potassium bromide phase. Materials. All the chemicals used were of either E. Merck or B.D.H. quality. Diacetylazine was prepared by the method reported by Busch et al.[4].
Preparation of diacetylazinedioxime Hydroxylamine sulphate (8"2 g, 0.05 mole) was dissolved in about 150 ml of cold distilled water. To it a previously cooled solution of sodium hydroxide (4.5 g, 0.112 mole, in about 100 ml of water) was added dropwise and the solution was stirred. Care was taken so that the resultant solution did not warm up during the addition. The sodium hydroxide solution was continued to be added till the hydroxylamine solution was just distinctly alkaline to litmus. Biacetylazine (8.4 g, 0-05 mole) was dissolved in about 80 ml of methanol and the solution was added in portions to the solution of hydroxylamine sulphate made just alkaline to litmus paper in the above mentioned manner and kept cooled in ice bath and the solution was stirred. A yellow solid gradually appeared. It was allowed to stand for nearly 30 min during which a considerable amount of solid was formed and settled down. It was filtered, washed thoroughly with water and then with a small amount of methanol and dried. Yield: 60%. Melting point of the product alter crystallisation from methanol is 2200C. (Found: C, 49.07; N, 28.18; H, 7.24. Calc. for CsN,O2H14: C, 48.48; N, 28.28; H, 7.07%.) 14. P.W. Ball and A. B. Blake, J. chem. Soc. A, 1415 (I 969). 15. J. E. Andrew, P. W. Ball and A. B. Blake, Chem. Comm. 143 (1969). 16. B. N. Figgis and J. Lewis, In Modern Coordination Chemistry (Edited by J. Lewis and R. G. Wilkins), p. 415. Interscience, New York (1960).
Diacetylazine-dioximato metal complexes
1317
Preparation of bis( diacetylazine-dioximato )di-copper( l l ) A warm solution of cupric nitrate in acetone was added in portions to a solution of diacetylazinedioxime in acetone (ligand:metal salt :: 1:1) and the mixture was stirred. A green compound was formed immediately. It was filtered, washed thoroughly with acetone and dried. The solid does not melt up to 260°C. (Found: Cu, 24-2; N, 20.97. Calc. for CsN402H12Cu: Cu, 24.48; N, 21.58%.)
Preparation of bis( diacetylazine-dioximato )di-nickel( l l ) tetrahydrate A warm solution of nickel acetate tetrahydrate (0.49 g, 0.002 mole) in about 50 ml of distilled water was added dropwise to a solution of diacetylazine-dioxime (0.39 g, 0.002 mole) in about 30 ml of dimethylformamide and the mixture was stirred. A reddish solid was formed immediately. After nearly 15 rain of stirring it was filtered, washed thoroughly with water and finally with dimethylformamide. On drying in vacuo a brown mass was obtained. It does not melt up to 260°C. (Found: Ni, 19"92; N, 18"85. Calc. for CsN402H12Ni, 2H20: Ni, 20' 19; N, 19"26%.)
DIACETYLAZINE-DIOXIMATO METAL CHELATES Cu(II) AND Ni(II); THEIR I.R. SPECTRA AND MAGNETIC PROPERTIES
OF
S. SATPATHY and B. SAHOO Indian Institute of Technology, Kharagpur-2, West Bengal, India
(Received 28 September 1970)
Abstract-Diacetylazine-dioxime and its Cu(II) and Ni(II) complexes have been prepared. Assignments of i.r. bands have been made for N - O - H bending, C - - N (azine), ~ N (oxime) and N - O stretching mode. The spectra evince that diacetylazine-dioximate ion is bonded to Cu(II) and Ni(II) in a bi-bidentate manner. Magnetic susceptibility values over a range of temperature show the presence of antiferromagnetic exchange interaction in these systems. INTRODUCTION
Irq Arq earlier paper[l] it was shown that salicylaldazinate ion acts as a dichelating agent with Cu(II), Ni(II) and Co(II), and functions as a tridentate chelating agent with Fe(II). In order to further know the manner in which tetrafunctional azine ligands are coordinated and the properties of such complexes, studies have been carried out with a new azine ligand, diacetylazine-dioxime, CsHI~N40~H2, (abbreviated as DAADOH2). Its Cu(II) and Ni(II) complexes are reported here. Their i.r. spectra indicate that D A A D O forms dichelate complexes with Cu(II) and Ni(II) and the magnetic susceptibilities of the complexes over a range of temperature show the presence of antiferromagnetic exchange interaction in these systems. RESULTS AND DISCUSSION
I.R. spectra
The important vibrational bands of the ligand and the metal complexes are given in Table 1. The most probable structure of D A A D O H ~ is illustrated in Fig. 1. The i.r. spectra of the ligand show multiple bands in the region 3300-2700 cm -1 indicating strong hydrogen bonding in the ligand involving N - O - H group. Further, they are in coincidence with C - H stretching vibrations. The O H stretching vibrations of several oximes involving intramolecular or intermolecular hydrogen bonding are found to occur in 3250-2350 cm -1 region [2,3].
:-%_:-% \O--H"
"H--O/
Fig. 1. 1. S. Satapathy and B. Sahoo, J. inorg, nucl. Chem. 32, 2223 (1970). 2. A. Palm and H. Werbin, Can. J. Chem. 31, 1004 (1953). 3. R. Blinc and D. Hadzi, J. chem. Soe. 4536 (1958). 1313
1314
S. S A T P A T H Y
and B. S A H O O
Table I. Principal i.r. absorption bands for biacetylazinedioxime and its copper(II) and nickel(II) complexes (frequencies in c m -~)
Cu(CsH12N402)
Ni(CsH12N402) 2H20
3125 s (bd) 2849 sh 1672 s
3279 s 2778 w
3226 s (bd)~ 2778 w J
1595 1429 1351 1121 1024 970 930 780 758
1587 1481 1370 1205 1104 1010 990 828 758
1613 1563 1471 1353 1178 1087 I010 980 766 741
CsH~2N402H2
s m s s s s s s m (bd)
m ms s ms s m m s m (bd)
m m s ms ms s w ms w / m (bd)
1
Tentative band assignments
O - H and C - H stretch O - H deformation of N O H group H 2 0 deformation ~N stretch ~N stretch CH3 deformation CH3 rock N-Ostretch
CH~ deformation vibrations
s = strong; m = m e d i u m ; w = weak; m s = m e d i u m strong; bd = broad; sh = shoulder.
A salient feature of the spectra of the ligand is a strong and sharp band at 1672 cm -1 which has been assigned to O - H deformation vibration of the N O H group. This assignment is further strengthened since this band does not occur in the metal complexes where the O - H bonds have been broken in the formation of the metal complexes. I.R. spectra of metal complexes with dimethylglyoximeand with cyclohexane 1:2 dione dioxime show the presence of O - H deformation vibration in the region 1650-1820 cm -1 [3]. The spectra of the ligand as well as metal complexes have certain features in the region 1600-900 cm -1 which are particularly useful as evidence of structure. The first band in this region in the ligand and its metal complexes is found in the region 1600-1560 cm -1 which has been attributed to the ~ N stretching vibration of the azine group. In the spectra of azines and their metal complexes this band appears between 1670-1527 cm -~ [1,4-6]. The next band appears in the region ~ 1485-1430 cm -1 and has been tentatively assigned to ~ N stretching vibration of the ~ N O H group. The unusually lower value of the ~ N group possibly arises due to high degree of conjugation in the ligand. The above assignment is further based on the findings of several earlier workers. In simple oximes [2], the ~ N band appears in the region 16601618 cm -~. In quinoneoximes [7] this band appears at smaller wave numbers (1570-1520 cm -j) which are explained in terms of a strong conjugation with the quinonoid double bonds. Similarly in 2-pyridine aldoxime [8] and in its uncharged metal complexes the ~ N band (acyclic) has been found in 1519-1505 cm-L In 4. 5. 6. 7. 8.
W . J . Stratton and D. H. Busch, J..4 m. chem. Soc. 82, 4834 (1960). R. G. R. Bacon and W. S. Lindsay, J. chem. Soc. 1382 (1958). W . J . Stratton, J. Inorg. Chem. 9, 517 (1970). D. Hadzi, J. chem. Soc. 2725 (1956). R . A . K r a u s e , N. B. Colthup and D. H. Busch, J. phys. Chem. 65, 2216 ( 1961).
Diacetylazine-dioximato metal complexes
1315
dimethyl glyoxime the first band, which is probably the ~ N band appears [9] at 1450 cm -1 and in its metal complexes the ~ N band is located in the region 1560-1490 cm -1 [3]. Our next attempt was to look for the N - O stretching absorption band. Usually, for simple oximes [ 10], N - O stretching bands appear between 960-930 cm -~ and for quinoneoximes[7] near 1000cm -~. In dimethylglyoxime[3] and its metal chelates a couple of bands are located in the region 1250-900 cm-' and has been attributed to N - O stretching vibration. In pyridine aldoxime [8] the band is found at 982 cm -~ but in its metal chelates a group of three bands are observed in the region 1200-950 cm -1. Since it was not possible in the latter case to make an unambiguous assignment to these bands, the band in the middle of the group was arbitrarily chosen as representing the N - O band. In the present case a group of three bands are observed in the region 1100-900 cm-' in the ligand as well as in its metal complexes- a situation analogous to that of pyridine aldoximato metal complexes. It is difficult to make an unequivocal assignment to these bands and in view of this, the band in the middle of the group has been chosen as the N - O stretching band. This band is generally situated at a relatively higher frequency region as expected. As can be seen from the spectral data, the bands for C : N and N - O groups do not split. Besides, there is one to one correspondence for all other bands in the ligand and in its metal complexes in the region 1600-900 cm-L The above spectral data provide the logical conclusion relating to the structure of the complexes, i.e. symmetric bi-bidentate bonding of the ligand with Cu(II) and Ni(II); and the most probable structures of the complexes may be represented as shown in Fig. 2. CH3 CH3 CHs CH3 \ / \ /
O
~ 2
Fig. 2.
M 2
O
M 2+ = Cu 2+, Ni 2+.
Magnetic susceptibility Magnetic properties of the compounds have been studied over the temperature range 90°K to 300°K. Replicate determinations have been carded out on separately prepared samples. The resultant susceptibilities, (XM), were corrected for diamagnetism[11] and temperature independent paramagnetism (t.i.p.). The t.i.p. values 60 x 10-~ c.g.s., e.m.u, and 240 x 10-e c.g.s., e.m.u, were used for Cu(II)[12] and Ni(II)[13] ion respectively. The effective magnetic moment,/ze,, has been calculated at each temperature employing the expression /Zerf=2"83 (x~T) +in 9. K. Nakamoto, I.R. Spectra of Inorganic and Co-ordination Compounds p. 195. Wiley, New York 1963. 10. A. Palm and H. Werbin, Can.J. Chem. 32,858 (1954). 11. B. N. Figgis and J. Lewis, In Modern Coordination Chemistry (Edited by J. Lewis and R. G. Wilkins), p. 403. Interscience, New York (1960). 12. B.N. Figgis and R. L. Martin, J. chem. Soc. 3837 (1956). 13. B.N. Figgis, Introduction to Ligand Fields Chap. 10. Interscience, New York.
1316
S. S A T P A T H Y and B. S A H O O
(Table 2). Graphs of 1/X'~ against temperature gave straight lines for both the compounds and both yielded negative values of 0 . - 160°K a n d - 149°K for Cu(II) and Ni(II) complexes respectively. The presence of antiferromagnetic exchange interaction is clearly implied by the decrease in magnetic moment per nickel ion from 2-67 B.M. at 304°K to 1.99 B.M. at 87°K and per copper(II) ion from 1.17 B.M. at 303°K to 0.87 B.M. at 91°K respectively and from their respective negative Weiss constants. The most obvious fact about these complexes is that the metal ions are bridged by a conjugated system. Among polynuclear complexes, where metal ions are bridged by a conjugated system, superexchange interactions have been studied only in few cases. Ball et al.[14,15] have for the first time and only recently reported spin-spin interaction between two Ni 2+ ions and two Co z+ ions bridged by some dichelating agents containing conjugated systems. Table 2. Magnetic susceptibilities, X~, (c.g.s., e.m.u., after correction for t.i.p, and diamagnetism as described in the text) per formula weight as indicated Cu(CsH12N40~) : 0 = - 160°K 252 237 210 641 665 707 1"13 1"12 1.09
T(°K) 106 x X~ /~en(B.M.)
303 568 1"17
273 607 1"15
195 747 1"08
165 812 1"03
129 913 0"97
T(°K) 106 x X~ /~e~ (B.M.)
304 2941 2"67
Ni(CaHI~N402) 2H20 : 0 = - 149°K 259 240 224 205 183 3321 3436 3596 3783 4011 2"62 2"57 2"54 2"49 2"42
108 5160 2" 11
87 5712 1"99
91 1062 0"87
EXPERIMENTAL Apparatus. Magnetic susceptibilities were measured by the Guoy method with Hg[Co(CNS)4] as calibrant[16]. Current through the magnet was maintained by a stabilised power supply (supplied by Toshniwal & Co., India). The temperature was controlled by a liquid air cryostat and measured with a copper constantan thermocouple. The measured susceptibility of Cu(CHaCO2)2H20 agreed satisfactorily over the range of 80°-300°K [ 12]. I.R. spectra were taken by Perkin Elmer i.r. spectrophotometer in potassium bromide phase. Materials. All the chemicals used were of either E. Merck or B.D.H. quality. Diacetylazine was prepared by the method reported by Busch et al.[4].
Preparation of diacetylazinedioxime Hydroxylamine sulphate (8"2 g, 0.05 mole) was dissolved in about 150 ml of cold distilled water. To it a previously cooled solution of sodium hydroxide (4.5 g, 0.112 mole, in about 100 ml of water) was added dropwise and the solution was stirred. Care was taken so that the resultant solution did not warm up during the addition. The sodium hydroxide solution was continued to be added till the hydroxylamine solution was just distinctly alkaline to litmus. Biacetylazine (8.4 g, 0-05 mole) was dissolved in about 80 ml of methanol and the solution was added in portions to the solution of hydroxylamine sulphate made just alkaline to litmus paper in the above mentioned manner and kept cooled in ice bath and the solution was stirred. A yellow solid gradually appeared. It was allowed to stand for nearly 30 min during which a considerable amount of solid was formed and settled down. It was filtered, washed thoroughly with water and then with a small amount of methanol and dried. Yield: 60%. Melting point of the product alter crystallisation from methanol is 2200C. (Found: C, 49.07; N, 28.18; H, 7.24. Calc. for CsN,O2H14: C, 48.48; N, 28.28; H, 7.07%.) 14. P.W. Ball and A. B. Blake, J. chem. Soc. A, 1415 (I 969). 15. J. E. Andrew, P. W. Ball and A. B. Blake, Chem. Comm. 143 (1969). 16. B. N. Figgis and J. Lewis, In Modern Coordination Chemistry (Edited by J. Lewis and R. G. Wilkins), p. 415. Interscience, New York (1960).
Diacetylazine-dioximato metal complexes
1317
Preparation of bis( diacetylazine-dioximato )di-copper( l l ) A warm solution of cupric nitrate in acetone was added in portions to a solution of diacetylazinedioxime in acetone (ligand:metal salt :: 1:1) and the mixture was stirred. A green compound was formed immediately. It was filtered, washed thoroughly with acetone and dried. The solid does not melt up to 260°C. (Found: Cu, 24-2; N, 20.97. Calc. for CsN402H12Cu: Cu, 24.48; N, 21.58%.)
Preparation of bis( diacetylazine-dioximato )di-nickel( l l ) tetrahydrate A warm solution of nickel acetate tetrahydrate (0.49 g, 0.002 mole) in about 50 ml of distilled water was added dropwise to a solution of diacetylazine-dioxime (0.39 g, 0.002 mole) in about 30 ml of dimethylformamide and the mixture was stirred. A reddish solid was formed immediately. After nearly 15 rain of stirring it was filtered, washed thoroughly with water and finally with dimethylformamide. On drying in vacuo a brown mass was obtained. It does not melt up to 260°C. (Found: Ni, 19"92; N, 18"85. Calc. for CsN402H12Ni, 2H20: Ni, 20' 19; N, 19"26%.)