VoL 8,No. 9,Sqbtember 1969
AROMATIC N-OXIDECOMPLEXES 1879 CONTRIBUTION FROM
THE
DEPARTMENT OF CHEMISTRY,
TEXAS CHRISTIANUNIVERSITY,FORTWORTH,TEXAS76129
The Structure and Properties of Complexes Formed between Aromatic N-Oxides and Copper(I1) Compounds BY W. H. WATSON
Received February 2, 1969
-4variety of complexes may be formed between aromatic N-oxides and copper(I1) compounds. The complexes have been classified as (a) low magnetic moment 1:1complexes, (b) low and normal magnetic moment 2 : 1 dimeric complexes, (c) trans and distorted cis 2: 1 monomeric complexes with normal magnetic moments, (d) polymeric complexes, (e) adducts of the above complexes, and ( f ) miscellaneous complexes. The structures of these complexes are discussed and the infrared spectra and magnetic properties are rationalized in terms of molecular structure and intermolecular interactions.
Introduction There have been many reports on the physical propperties of complexes formed between aromatic N-oxides and copper(I1) halide compounds since their inital preparation a few years We initially were interested in these complexes because of interactions between the metal ions, which resulted in reduced magnetic moments. An understanding of the isolated magnetic interactions and the chemical properties of these systems should permit us to synthesize complexes with specific magnetic properties. After a preliminary study had been completed,13it was evident that the chemistry of copper(I1) ions when mixed with aromatic N-oxides was quite complex. This report is an attempt to enumerate and rationalize the complexities of these systems. The aromatic N-oxide-copper( 11) complexes may be divided into general categories which reflect their chemical composition and physical properties. Most complexes which have been isolated and characterized are (a) low magnetic moment 1: 1 complexes, (b) low and normal magnetic moment 2 : 1 dimeric complexes, (c) trans and distorted cis 2 : 1 monomeric complexes with normal magnetic moments, (d) polymeric complexes, (e) adducts of most of the above complexes with small polar molecules, like DMSO, DMF, CHIOH, and HzO, or (f) miscellaneous complexes. The crystal structures (1) J. V. Quagliano, J. Fujita, G. Frans, D. J. Phillips, J. A. Walmsley, and S. Y.Tyree, J . A m . Chem. Soc., 83,3770 (1961). (2) R. L. Carlin, ibid., 83,3773 (1961). (3) C. M. Harris, E. Kokot, S. L. Lenzer, and T. N. Lockyer, Chem. I n d . (London), 651 (1962). (4) M. Kubo, Y.Kurodo, M. Kishita, and Y.Muto, Austvalian J . Chem., 16, 7 (1963). (5) S. Kida, J. V. Quagliano, J. A. Walmsley, and S. Y . Tyree, Spectvochim. Acta, 19, 189 (1963). (6) M. Kato, H. B. Jonassen, and J. C. Fanning, Chem. Rev..,64, 99 (1964). (7) H. B. Jonassen, Y.Muto, and M. Kato, U . S.Govt. Res. Rept., 39 (9), 20 (1964). (8) W. E. Hatfield and J. S. Paschal, J . A m . Chem. Soc., 86,3888 (1964). (9) W. E. Hatfield, Y.Muto, H. B. Jonassen, and J. S. Paschal, Inovg. Chem., 4 , 97 (1965). (10) H. 1,. Schafer, J. C. Morrow, and H. M. Smith, J . Chem. Phys., 42, 504 (1965). (11) W. E. Hatfield and J. C. Morrison, Ino!’g. Chent., 6 , 1390 (1966). (12) W. B. Hatfield and F. L. Bunger, i b i d . , 5 , 1161 (1966). (13) M . R . Kidd, R . S. Sager, and W. H. Watson, i b i d . , 6, 946 (1967). (14) K. S. Sager, K. J. Williams, and W. H. Watson, i h i d . , 6, 951 (19R7). (15) R. Whymau and W. E. Hatfield, ibid., 6, 1850 (1967). (16) S . J. Gruber, C. M. Harris, E. Kokot, S. L. Lenzer, T. N. Lockyer, and E. Sinn, Australian J . Chem., 20, 2403 (1967). (17) R. Whyman, D. B. Copley, and W. E. Hatfield, J . A m . Chem. Soc., 89, 3135 (1967). (18) R. S. Sager and W. H. Watson, Inorg. Chem., 1, 2035 (1968).
of a number of complexes have been determined, and we will use these data to discuss their geometry and physical properties. There have been more than 100 aromatic N-oxide-copper(I1) complexes prepared, and we have included most of them in Table I. Assignments to structural categories in some cases are based upon limited data and are subject to revision when additional results become available ; however, the generalizations proposed in this paper should be of value in formulating future experiments. Experimental Section Materials.-All aromatic N-oxides, not previously reported in the literature, were prepared from the corresponding amines by peroxide oxidation in acetic acid. The amines were purchased from Aldrich Chemical Co. and Reilly Tar and Chemical Co. or were synthesized by standard procedures. The aromatic N-oxides were recrystallized from ethanol and characterized by their melting points, elemental analyses, and spectra. The preparation and characterization of copper(I1) complexes have been described adequately in many of the early papers included in the references. Enquiries concerning specific complexes or their physical properties may be referred to the author. Spectra.-Infrared spectra were obtained with Perkin-Elmer Model 235 and Beckman Model IR-10 spectrophotometers using Nujol mulls or reflectance techniques. All infrared spectra were calibrated with peaks from a polystyrene film. The spectra on the IR-10 were scale expanded. Molecular Weights.-Molecular weights were determined with a Mechrolab osmometer, Model 301A, using distilled nitroethane as a solvent. Magnetic Susceptibility.-Magnetic susceptibilities were measured by the Faraday method using a Cahn automatic electrobalance, Model RH. Electrobalance output and thermocouple voltage were measured with a Hewlett-Packard digital voltmeter, Model 3440A, with a Model 3443A range plug-in unit. A digital recorder, Hewlett-Packard Model 562A, printed the ouput of the voltmeter upon receiving a 10-V pulse from an automatic control system. The automatic control system performed all switching for the magnet control system and reading. A thermocouple of silver with 0.37 atom % gold and gold with 2.10 atom yo cobalt was used to measure the temperature. The thermocouple measuring junction was placed directly below the sample container and the reference junctiou was immersed in a n ice bath. The temperature dependence of ammonium manganese sulfate hexahydrate was used to calibrate the thermocouple at low temperatures, and mercuric tetrathiocyanatocobaltate(I1) was used a t higher temperatures. A helium dewar was used for all low-temperature measurements. A special heating unit was constructed for measurement above room temperature. After the usual diamagnetic corrections had
IS80 IN. H. WATSON
Inorganic Claernistry 'rhHLl2 P,
1 2J, K
UM
ux-o,'
K
I'UU
u1,o
R
1: 1 Complexes
l(PYO)CuCl2la [ (2-CHapyO)CuClzI z [ (3-CHspyO)CuClzl~ 2 U C ~ Z ] [(~-CH~~~O)C [(2,4-(CHa)z~~O)CuC1,1 L [ (2,6-( C H ~ ) Z P Y O ) C U2C ~ ~ I 1(2,4,6-(CHa)apyO )CuC121B [(4-Cl(pyO))CuCl212 [(4-Br(pyO))CuC121~ [ (4-OHpyO )CuCL]2 [ (4-CNpyO)CuCl2l2 [ ( 4 - ~ \ ~ 0 ~)CuC1212 pyo [( ~ - C H ~ O P Y O ) C U C ~ Z I ~ [(4-CsH~Op~O)CuC1z]z [( ~ - ~ - C ~ H ~ P Y O ) C U C L I Z [ ( ~ - C G H S P Y O ) C zU C ~ ~ ] [ (4-B~(pyO))C~Clz]2 [ ( ~ - C H ~ O H ~ ~ O )2 C U C ~ ~ ] [(4-C00CHspyO)C~Cl~]a [ ( ~ - C O O C ~ H ~ ~ ~ O )2 C U C I ~ ] [ (3-Cl(pyO1)CUC1212 [ ( 3 - 0 H ~ ~ O ) C u C 2l a l [(3-CHaOpyO)C~Clp]z [( ~ - C O O H ~ Y O ) C U 2 C~~] [(3-COOCH3pyO)CuCia]z [ (3-C00CzHspyO)C~C1~] 2 [ (quinO)CuCL]2 [ (4-CH3quinO)CuCl~] z [(6-CH3quinO)CuC1~] 2 [(pyO)CuBrd~ [ (2-CHspyO)CuBrp]~ [ (3-CHspyO)CuBr~l z [ (4-CHapyO)CuBrd z [(2,6-(CHa)zpyO)CuBruIu
0.69-1, 06,L-d 0.63
616,e 720,' 716
12030
330, 311*
0.55,d 0.975 0 , 52,d,j 0.49 0.22d 0.68,' 0 . 2 ~ ? ~ 0 ,63i 0.58,i 0 . 2 8 0.30 0i 0.36 1.01," 1.20,J0 . 9 5 0.33 0.30 0.56 0.32 0.48 0.38 0.41 0,501 0.46l 0.38l 0.55l 0.53l 0.56l 0 . 4gZ 0,' 0 . 3 G ~ 0 . 561". 0 .4 1' 1 ) 0 ,24-0 .OWf/
680-810' 986,b 829
1253 1203;j 1204
316;" 323 327, 31Zh
I..
326h 327h 317;" 3 14
... ...
930-1090' 960-1080i 1090,k 1064 1050 2 150b 966 529 994 1027 776 966 838 941 923
...
... 1208;j 1205
... 1210i
...
...
...
,..
... ... ... ... . . I
... ... ... .
.
.., ...
305;h310 324;h 324 320 316, 310 316 338, 309 316, 303 329
... ... ...
... ...
I
...
, . .
344, 3327'3 334, 3257'L 340, 328va
...
...
...
1200i
...
. ~ .
890 1080'
1234 1203;i 1208 1198
...
1(4-Cl(pyO ))CuBnl z
...
1201
[ (4-CNpyO)CuBrzlz [ (4-N02pyO)CuBrz]z [ (4-CHaOpyO)CuBrz]2
143h
1238, 1 2 2 3 1205
...
... ... ... ~
*
*
... . . ~
...
...
...
[(4-CnH~OpyO)CuBr21~ [(4-t-C4HspyO)CuBrz]z I (4-CcH~pyO)CuBr~l2 [ (4-COOC2H&pyO)CuBr~1 z [ (3-Cl(pyO))CuBr~l 2 [ (3-Br(pyO))CuBrrl; [(3-0HpyO)CuBr~] 2 [(3-COOHpyO)CuBrZ12 [ (quinO)CuBr2] 2 [ (4-CHaquinO)CuBr2]2 [ (4-Cl(quinO)CuBr2] 2 [ (6-CHsquinO)CuBrz]z [ (4-C1-6-CHsquinO)CuBr~]z [ (3-XO2-6-CHaquinO)CuBrl]2
...
...
...
940-1100^. 960-11201
...
...
1207 1200 1200 1213 1212 1209 1208 1199
,,.
...
[(2,4,6-(CH3)3pyO)CuBr~l~
...
1217
...
...
... ...
...
...
... ... ... ...
... ...
...
... ...
...
... ...
...
... ...
,., .
I
.
...
...
A\dductsof 1: 1 Conlplcxes
~(~)~~)CllCl~(L)~I~)J~ \(pyO)CuClz(DMSO)]n [(Z-CH~P~O)CUC~~(CHSOH)]B [(~-CH,~~O)CUC~~(DMSO)]~ [ (3-CHspy 0 )CuC12(DMSO)]2 [ (4-CHapyO)CuClz(DMSO I) 2 [ ( 4 - 0 H p y O ) C ~ C l ~ ( H)212 20 [ (2,6-{CHa)yyyO)CuClB(DMSO)]z [ (pyO)CuBr2(DMF)]2 [(pyO)CuBr2(DMSO)lz [(4-CH3pyO)CuBr2(DMSO)]z
1 %);< 1203i
...
...
... ...
J
...
... ...
...
... ... ...
0.31 0 . 4Bd 1.12d 0.971
...
...
...
..,
...
... ...
1153
1217
316. 332
... ... ... ..,
...
...
1202j
...
1211i
AROMATIC N-OXIDECOMPLEXES1881
Vol. 8, No. 9,Sefdember 1969 TABLEI (Continued) Compounda
P,
BM
25, K
2: 1 Low and Normal Motnent Dimers 0.46,f 0.63d ... 1.4f 242f 1.8gb ... 1.88,f 1 . 9 l C ...
UN-O,K
1223, 1206~ 1211, 12029 1211, 1202
310, 280h
...
...
...
...
1.33f
ucu-ci, K
...
...
...
...
trans 2 : 1 Monomers
... ...
1.95
... ...
1.90i 1.913 1.75i
... ...
...
...
...
...
341h 346h
...
...
...
1.88,
... ...
1.88" 1 . 8 f 1 , 1.93d ~ 1.97m 1.87% 1.81"
3Bh 322h 339, 316, 296"
... ... ...
...
... ... .
...
I
.
327h
... ...
... ... ...
.,.
Distorted cis 2: 1 Monomers
...
...
...
...
...
...
...
319, 297" 318, 330"
...
...
...
*..
1.91m
2: 1 Monomers
...
...
2.04; 1.89
...
...
.,*
1.961 ... 1.83" ... 1.83m 1.82~1 ... 1.85m ... 1 .98" ... Adducts of 2 : 1 Monomers 1.96f ... 1.96f ... Polymeric Complexes 1.22 ... 2.07" ... 1.6gm ... 1.91m ... I
.
... ...
... ...
...
.
Miscellaneous Complexes 1.62,b 1.80,j 2 . 0 9 ~ ...
...
...
...
I
.
.
... ... ...
...
... ...
... ...
315, 302, 2911 308, 290nA 307, 280m 306, 290m
... ... ... 1215, 12050
... ...
,..
... ...
p y 0 = pyridine N-oxide; quinO = quinoline N-oxide. * Reference 1. Reference 3. Reference 6. 6 Reference 10. f Reference 16. 0 Reference 5. h Reference 15. Reference 11. j Reference 9. IC Reference 8. Reference 21. Reference 17. n Mixture of trans and distorted cis forms. Commas separate more than one infrared band; semicolons separate more than one measurement of the same band. 5
been made, the experimental data for the dimeric complexes were least-squares fitted to the expression
X m 'Or
- NB[ -
3kT
1
+ 1 exp(2JlkT)
1
+ Na + C -
The term C accounts for any paramagnetic impurity which might be present. The impurity was assumed to obey the Curie law and have an effective moment of 1.90 BM. The percentage of paramagnetic impurity was small in all cases. Expressions for the magnetic susceptibility of more than two intereacting tran-
sitioh metal ions may be derived from the Heisenberg-DiracVan Vleck spin-coupling Hamiltonian.'S
Discussion
Cow Magnetic Moment 1 :1 Complexes.-The crystal structure of the 1: I complex formed between pyridine N-oxide and copper (II) -chloride, [ (CjHbNO)Cu C1, I,, was the first to be r e p 0 r t e d . 1 ~ ~The ~ ~ molecular structure as shown in these papers probably represents the complex in solution, and i t has been used extensively t o (19) K. Kambe, J . Phys. SOC.J a p a n , 6, 48 (1950).
Figure l.--Molecular
structures of Cu(I1) and Zn(I1) complexes with aromatic S-oxides. The structures have been idealized to facilitate discussion.
rationalize the physical properties of the crystalline solid. Unfortunately, a number of significant interand intramolecular interactions were omitted. The complex, structure 1 (see Figure 1) actually
should be described as an infinite chain of oxyxeiibridged dimers joined by n-eak chloride bridges.2" The (20) R.J. Williams, I
