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Thermal and electrical properties of organometallic coordination polymers based on centrosymmetric 1,5-naphthyridine derivatives
140
Notes
molecules and by the tetramer equation [8] for complexes of this symmetry type. Fortran IV programs were written and used to interpret the data with a D E C System 10 computer. A g-value of 2.13 was obtained from E P R spectra and used as a constant in the least-squares fitting process. In application of the dimetallic model, only the inplane interactions between copper ions (1 and 3) and (2 and 4) are taken into account (see Fig. 1). The best fit to the dimer equation [7] dictated by the Hamiltonian, H = - 23,S 1 • S2, yields 2J = - 308 cm -1 and N a = 54 × 10 -6 cgsu. For the application of the tetrametallic model, electron spin-spin interactions among all four copper ions are taken into account. The susceptibility equation [8] for a tetrametallic system of this Jype containing four centers of s =½ is based upon a spin-only isotropic HeisenbergDirac-Van Vleck model for which the Hamiltonian is H = -23,1(S 1 • 52)-2./2(52 " S 4 - [ - 5 1 • 5 3 ) - 23,3(S1 • S 4 "~52.53) - 23-453 • S 4. The spin-spin coupling constant, J~, represents the interaction between copper ions 1 and 2, while J4 is a measure of the interaction between coppers 3 and 4. The interaction between coppers 1 and 3 is equivalent to that between coppers 2 and 4, and is represented by 3"2. The interaction between coppers 1 and 4 is equivalent to that between coppers 2 and 3 and is represented by J3. The best fit of the tetramer equation [8] to the experimental data provided the following parameters: J~ = + 8 4 c m -1, ./2 = - 1 6 3 c m -~, 3 , 3 = - 5 7 c m -1, J 4 = 0 and N a = 10 x 10 -6 cgsu. From Fig. 2 it is evident that the tetramer model provides a better fit. The overall antiferromagnetic behavior of the compound is described primarily by the in-plane coupling defined by J2. Both the sign and magnitude of 3'2 may be somewhat expected based on the 3,-value determined by the dimetallic model, where 23" = - 3 0 8 cm -~ or 3 ' = - 154 cm -~. The interaction between copper ions 1 and 2, J~, might be expected to be positive based upon the 3,-value of + 1 0 c m -1 reported for dimetallic N,N'-ethylenebis(salicylideneiminato)copper(II) [9]. This Schitt base complex has only an out-of-plane interaction which is almost identical to that described by
Jt for the title compound. On making this comparison, it is difficult to rationalize why 3,, is so much higher than about 10cm-1; and it appears that such a comparison may be an oversimplification. A J3-value of - 5 7 cm -1 is in agreement with the values of 3'1 and 3'2, and a 3,:value of zero is expected because of the rather large distance over which a superexchange mechanism would be employed. Thus it has been possible to describe the magnetic properties of acetylacetonemono (o-hydroxyanil)copper(II) by use of a tetrametallic model which takes into account all of the spin-spin interactions in the molecule.
Acknowledgements--We are grateful for the support of this research by The Robert A. Welch Foundation under Grant No. AE-491 and by Organized Research of West Texas State University. The KiUgore Reseach Center West Texas State University
M. V. H A N S O N G. D. SIMPSON W. E. M A R S H G. O. C A R L I S L E
Canyon,TX 79016 U.S.A.
REFERENCES
1. M. Kishita, Y. Muto and M. Kubo, Aust. J. Chem. 10, 386 (1957). 2. G. A. Barclay, C. M. Harris, B. F. Hoskins and E. Kokot, Proc. Chem. Soc. 264 (1961). 3. G. A. Barclay and B. F. Hoskins, J. Chem. Soc. 1979 (1965). 4. P. E. Rush, J. D. Oliver, G. D. Simpson and G. O. Carlisle, J. Inorg. Nucl. Chem. 37, 1393 (1975). 5. B. N. Figgis and R. C. Nyholm, 3'. Chem. Soc. 4190 (1958). 6. J. Lewis and R. C. Wilkins, Modem Coordination Chemistry, p. 403 Interscience, New York (1960). 7. B. Bleaney and K. D. Bowers, Proc. Roy. Soc., Set. A, 214, 451 (1952). 8. J. E. Andrew, A. B. Blake and L. R. Fraser, 3". Chem. Soc., Dalton 477 (1976). 9. G. D. Simpson, G. O. Carlisle and W. E. Hatfield, 3'. Inorg. Nucl. Chem. 36, 2257 (1974).
J, inorg, nucl. Chem. Vol. 42, pp. 140-143 © P e r g a m o n Press Ltd., 1980. Printed in Great Britain
0022-1902/80/0101-0140/$02.00/0
Thermal and electrical properties of organometaHic coordination polymers based
on centrosymmetric 1,5-naphthyridine derivatives (Received 9 April 1979) We report thermal and bulk electrical characteristics of coordination polymers based on the centrosymmetric, tetradentate ligands 4,8-dihydroxy- 1,5-naphthyridine (DHNH2) and 4,8-dithiohydroxy- 1,5-naphthyridine (DTNH2). These novel aromatic ligands are formally analogous to 8-hydroxy-quinoline (oxine). In certain cases it has been shown that the incorporation of alternating aromatic molecules into a chain of metal ions as in coordination polymers produces materials which are electrical semiconductors [1] and the current study was undertaken with this in mind.
EXPERIMENTAL
Physical measurements. Thermogravimetry was performed using an R. L. Stone T G A - 5 B Thermobalance (Cahn electrobalance) in a flowing nitrogen/oxygen atmosphere unless otherwise indicated. Samples ranging in size from 12 to 27 mg were run at a heating rate of 5°C/min. IR spectra were taken on a Beckman IR8 spectrometer using KBr pellets. X-ray powder diffraction patterns were determined on a Hayes Powder Diffractometer using filtered C u - K a radiation (A = 1.5418 A.).
Notes Conductivity m e a s u r e m e n t s were taken with a Keithley 515 M e g o h m Bridge on powder samples pressed into the form of disks. Sample disks were consistently 1 cm in dia. and between 0.9 and 1 . 1 m m thick. Contact between bridge electrodes and sample disks was facilitated by spotting the disk with either H g - - I n alloy or silver conducting paint. Resistance readings taken at ambient t e m p erature in air or in vacuo were similar, but resistances taken in air slowly decreased as the sample adsorbed water vapor. Elemental analyses were performed by Galbraith Laboratories, Knoxville, Tennessee. Preparation of D H N coordination polymers. The ligand [2] (0.31 mmol) was dissolved in warm water by addition of sodium carbonate (0.31 mmol). The warm solution was added to an a q u e o u s solution of the appropriate metal salt and after several hours the precipitate was collected on a fritted glass funnel, washed with water, and dried over P2Os in vacuo at room temperature unless otherwise indicated. Each c o m p o u n d was ground to a powder before characterization. Yields were ca. 95%. Metal salts used were C u ( O A c ) 2 . H 2 0 , Ni(NO3)z-6HzO, C0(N03)2"6 H 2 0 , M n S O a ' H 2 0 , Fe(NO3)3"9 H 2 0 , ZnCl2, CdSO4, and Pb(OAc)2'3 H 2 0 . Preparation of D T N coordination polymers. T h e ligand [2] (1 retool) was dissolved in warm D M F (dried over Linde 4 A molecular sieve) and a warm solution of transition metal acetate (1 retool) in D M F was added. After several hours the precipitate was collected on a fritted glass funnel, washed with DMF, and dried over P2Os, first at room temperature and finally at 153°C. The brittle polymers were ground to powder before characterization. Yields were roughly quantitative.
DHN, Y = O DTN, Y = S
RESULTS A N D DISCUSSION D H N polymers were prepared in aqueous solution in the presence of base. The c o m p o u n d s were isolated as the
141
hydrates whose X-ray powder diffraction patterns consisted of several diffuse bands along with lower intensity distinct bands, indicating only a low degree of crystallinity. D T N polymers were prepared in dimethyl formamide without added base. These polymers were obtained as brittle, iridescent solids whose powder diffraction patterns exhibited two highly diffuse bands. T h e C o . D T N polymer was hygroscopic, as were all the dried D H N polymers to varying degrees. Dried N i . D H N changed color from (lark brown to light green upon absorbing water from the atmosphere. Analytical data for all polymers are given in Table 1. The metal:ligand ratio was found to be 1 : 1 in all cases. The Co-DTN polymer was apparently an oligomer of low molecular weight containing dimethyl formamide. In repeated preparations of C o . D T N , the characteristic color of Co z+ was observed in the product filtrate, indicating that precipitation of Co 2+ by D T N H 2 was incomplete. The IR spectra of all the D H N polymers were similar (Table 2). It has been reported [3] that the IR spectra of the various metal oxinates are also basically identical. There is little resemblance between the oxinate spectra and those of the D H N polymers. It is difficult to compare the D H N polymer spectra with the spectrum of D H N H 2 itself because D H N H 2 probably exists as the diketo tautomer in the solid state while the D H N units in the polymers are probably formally derived from the dihydroxy tautomer. That the polymers contain chelated D H N is indicated by the loss of the finely structured band centered at 3 0 5 0 c m J, present in the spectrum of D H N H 2 and due at least partly to N - H stretching vibration. Also the strong, broad carbonyl stretching vibration at about 1545 cm 1 in the spectrum of D H N H 2 is replaced in the polymer spectra by a sharp peak at about 1500 cm- J, corresponding apparently to an aromatic ring vibration. The IR spectra of the D T N polymers also resembled one another. For reasons given above, con> parison with the spectrum of D T N H 2 is difficull. Note, however, that the D T N polymer spectra have lost both the strong band at 1 1 8 4 c m t present in the DTNH., spectrum and due to C - - S , as well as the finely strnctured N - H bands above 3000 cm- ~. None of the polymers showed any sign of melting below 300°C. T G data for all polymers are given in Table 3. Each of the D H N polymers lost water below 200°C and then decomposed in a single step to yield the metal oxide. D T N polymers decomposed in two distinct stages. This is best explained by assuming loss of ligand in the first stage
Table 1. Analytical results Calculated (%) Compound
Color
Cu'DHN.½ H 2 0 * Ni-DHN.3 H20 Co.DHN.2-½ H20 Mn-DHN-1-1 H20 FeOH.DHN.H20* Z n - D H N .3 H 2 0 * C d . D H N .3 H~O* Pb' D H N Cu.DTN? Ni-DTN§ Co. D T N II
Dark green Light green Dark brown Brown Black-violet White White White Dark green Red-brown Green
Found (%)
C
H
N
Metal
C
H
N
Metal
41.29 35.21 36.38 39.69 38.28 40.20 33.59 26.16 37.56 38.29 38.25
2.17 3.69 3.43 2.91 2.81 2.32 1.94 1.10 1.58 1.61 1.61
12.04 10.27 10.61 11.57 11.16 11.72 9.79 7.63 10.95 11.16 11.15
27.31 21.51 22.31 22.69 22.25 27.35 39.29 56.41 24.84 23.39 23.46
41.81 35.03 36.24 39.56 38.41 40.38 34.02 26.02 37.34 38.56 37.98
1.98 3.83 3.76 3.13 2.62 2.22 2.14 1.20 1.71 1.83 2.12
I 1.97 10.03 10.60 11.42 11.05 11.78 9.82 7.47 10.72 11.3t) 10.06
27.04 21.36 21.42 22.53 22.66 26.71 37.71 56.05 24.8~.: 23. !6 17.7I:
* Dried at 195°C over P2Os. -t %S. Calculated: 25.07. Found: 24.89. + D e t e r m i n e d by TG. § %S. Calculated: 25.55. Found: 25.47. II %S. Calculated: 25.53. Found: 23.14.
142
Notes Table 2. Principal IR spectral bands (v, cm 1) Compound DHNH 2 Cu.DHN'½ H20 Ni'DHN'3 H20 Co.DHN'2-½ H20 Mn.DHN. 1-½ H20 FeOH.DHN.H20 Zn-DHN -3 H20 Cd.DHN -3 H20 Pb.DHN DTNH 2 Cu.DTN Ni.DTN Co.DTN
IR 3145 m, 3050 s, 2985 m, 2950 m, 2880 m, 1545 b-vs, 1390 s, 1310m, 1187s, 1173s, 1085 m, 826s, 795m 1548 m, 1490 vs, 1430 s, 1325 m, 1265 w, 1217 s, 1000 m, 827 m, 695 w 3300 b, 1550 s, 1500 vs, 1423 s, 1322 m, 1250 m, 1218 s, 996 m, 823 m, 695 w 3300b, 1550s, 1500vs, 1420s, 1320m, 1248m, 1215s, 995 m, 821 m, 695 m 3300b, 1550s, 1502vs, 1415s, 1330m, 1243 m, 1213s, 986 m, 818 m, 695 m 3400 b-w, 1547 s, 1496vs, 1420 m, 1323 m, 1257 w, 1212m, 999 m, 823 m, 695 m 3300 b, 1550 s, 1505 vs, 1425 s, 1335 m, 1250 m, 1220 s, 993 m, 832 m, 821 m, 695 m 3300 b, 1548 s, 1502 vs, 1417 s, 1332 m, 1240 m, 1217 s, 986 m, 831m, 815 m, 695 m 1548s, 1500vs, 1425s, 1331m, 1250m, 1217m, l191s, 990 m, 847 m, 807 m, 695 m 3135m, 3100m, 3065 m, 1540s, 1515m, 1400s, 1310m, 1235m, 1213m, l184vs, 1065s, 1055s, 790s 1480 s, 1365 s, 1242 m, 1208 m, 1078 w, 829 m, 787 s, 696 m, 1485 s, 1378 m, 1250 w, 1210 s, 1080 w, 840 w, 800 s, 695 w 3400w, 3015w, 2915w, 1550w, 1485 vs, 1370s, 1243m, 1210 s, 1083 m, 825 m, 786 m, 695 m
Table 3. Results of thermogravimetric studies Weight loss (%) Compound
Ta (°C)*
Species volatilized
Cu.DHN.½ n 2 0
50-150 340-460 50-200 410-500 30-185 270-305 30-210 255-300
½H20 CsH4NzO 3 H20 CsH4N20 2½ H20 CaH4N20 2 H20 CaH4N20
FeOH.DHN-1½ H20
50-120 295-325
1½H20 CsH5N2Olo/2 )
Zn.DHN.2 H20
30-140 385-515
2 H20 CaH4N2 O
Cd.DHN.2 H20
30-155 445-540
Pb-DHN
Ni-DHN-3 H20 Co.DHN.2½ H20 Mn.DHN-2 H20
Found
Calculated
3.0 62.0 20.7 52.1 16.0 54.3 15.0 55.5
3.9 61.9 19.8 52.8 17.1 54.6 14.3 57.4
9.2 59.2
%Metalt
27.9(27.3 CuO) 21.4(21.5 NiO) 21.8(22.3 Co304) 21.3(21.9 Mn304)
10.4 58.9
21.5(21.5 Fe203)
12.4 56.4
13.8 55.1
25.0(25.0 ZnO)
2 H20 CsH4N20
10.3 46.6
11.7 46.7
34.9(36.4 CdO)
415-475
CsHaN20
38.9
39.2
55.4(56.4 PbO)
Cu.DTN
325-510 650-730
CsH4N2S S
59.8 9.2
62.6 6.3
25.1(25.1 CuO)
Ni-DTN
470-610 690-770
CsH4NzS S
56.3 15.9
63.8 6.4
21.8(23.2 NiO)
Co.DTN
30-100 200-550 710-800
(H20) CsHaN2S S
3.3 59.1 13.5
63.8 6.4
17.7(23.5 Co3Oa)
* From first significant weight loss to beginning of plateau. t Calculated values in parentheses with species weighed.
143
Notes accompanied by partial oxidation, giving a mixture of metal sulfide and metal sulfate which is then completely oxidized to the metal oxide in the second stage of decomposition. T G decomposition temperatures for the Zn z÷, Cd 2+, Pb 2+, and for the two Ni 2+ polymers, are remarkably high. Powder resistivity for all the polymers was > 1 0 ~ 2 0 h m c m ~. This may reflect the apparent low degree of crystallinity of the materials. Macrocrystals of the polymers could not be obtained by simple recrystallization since the c o m p o u n d s were highly insoluble in c o m m o n solvents.
Acknowledgement--Financial support by the Robert A. Welch Foundation and helpful conversations with Professor H. Steinfink are gratefully acknowledged.
Department of Chemistry The University of Texas at Austin Austin, T X 78712 U.S.A.
S. B. B R O W N M, J. S. D E W A R
REFERENCES 1. M. J. S. Dewar and A. M. Talati, J. Am. Chem. Soc. 86, 1592 (1964); H. Meir, Organic Semiconductors, Verlag Chemic, W e i n h e i m (1974); G. Manecke in
XXIVth International Congress of Pure and Applied Chemistry, Hamburg, Germany, 1973, Vol. 1, High Polymers, p. 155. Butterworths, London (1974). 2. S. B. Brown and M. J. S. Dewar, J. Org. Chem. 43, 1331 (1978). 3. R. G. Charles, H. Freiser, F. Friedel, L. E. Hilliard, and W. D. Johnston, Spectrochim. Acta 8, 1 (1956).
1. inorg, nucl. Chem. Vol. 42. pp. 143-145 © Pergamon Press Ltd.. 1980. Printed in Great Britain
0022-1902/80/01014)143/$02.1X)/0
2-Ethylsuifinylpyridine N-oxide complexes prepared from lanthanide(lll) perchlorates and chlorides (Received 9 May 1979) Previously [1] we c o m m u n i c a t e d o u r initial findings of only the l a n t h a n u m complex, [La(CTHgNO2S)4IC104]3, in conjunction with the nickel(II) complex of 2ethylsulfinylpyridine N-oxide (L). More recently we have reported on the transition metal ion complexes formed with 2-methylsulfinylpyridine N-oxide [2] and the title ligand [3]. Here we wish to report on the preparation and I R spectra of seven additional lanthanide complexes prepared from perchlorate salts and two solids prepared using hydrated lanthanide chlorides. A s indicated in o u r previous reports involving this ligand [1, 3], powdered microcrystilline solids can only be obtained by triturating the oils resulting from the preparative mixtures with n u m e r o u s portions of anyhydrous ether in a nitrogen atmosphere. Once formed, the solids m u s t be stored in a v a c u u m oven at 80°C while not in use. T h e partial elemental analysis of the dried solids are shown in Table 1. It is of interest to note that only the l a n t h a n u m complex was isolated free of solvent molecules. In addition, the n u m b e r of ligands per metal ion is less, excepting the p r a s e o d y m i u m solid, than the four found for lanthanum. However, the coordination n u m b e r of eight reported [1] for [LnL4](CIO4) 3 m a y be achieved for the heavier metal ions of the series by incorporation of solvent molecules in the coordination sphere. In Table 2 assignments of the I R bands pertinent to the establishment of the nature of these complexes are compiled. T h e wave n u m b e r values are assigned from spectra recorded on a B e c k m a n IR 12 as K B r disks and nujol mulls between CsI plates. The N - O stretching frequency, v N O , is shifted to lower wave n u m b e r s in all the metal complexes compared to the free ligand which is consistent with coordination of the N-oxide oxygen to metal ions [4]. It is of interest to note that the shift to lower wave n u m b e r s of 2 4 - 3 2 cm t is JINC Vol. 42, No. l--J
Table 1. Partial elemental analysis of 2ethylsulfinylpyridine N-oxide (L) complexes prepared from lanthanide(III) perchlorates and chlorides
Compound LaL4(C104)3 PrL4(H20)(CIO4)3 SmL3(CH3OH)(HzO)x (C10,)3 GdL3(CH3OH)2(CIO4)~ DyL3(CH3OH)2(CIO4)3 HoL3(CH3OH)(H20)x (C|O4)3 ErL3(CH3OH)2(C104)3 YbL~(CH3OH)z(C104)3 SmL2(CH3OH)C13 ErL2(CH3OH)CI3
Calculated C H N
C
Found H
N
29.97 3.23 4.99 29.90 3.37 4.85 29.44 3.35 4.91 29.33 3.39 4.77 26.10 3.29 4.15 26.(/3 3.55 4.22 26.73 3.41 4.07 27.35 3.50 4.48 26.60 3.40 4.05 26.63 3.50 4.48 25.73 3.24 4.09 25.59 3.75 3.96 26.48 26.33 28.54 27.80
3.38 3.36 3.52 3.42
4.03 4.01 4.44 4.32
26.20 26.50 28.61 28.16
3.43 3.74 3.45 3.37
4.07 4.31 4.34 4.40
s o m e w h a t less than the shift observed for divalent transition metal ions, 3 2 - 4 2 cm 1, and considerably less than the 4 4 - 4 9 cm -1 range found for the trivalent transition metal ions of this ligand. Similarly, vSO is shifted to lower wave n u m b e r s in the lanthanide complexes when compared to the free ligand confirming that it is also b o u n d to the lanthanide ion via oxygen [5]. Again the shift is somewhat less than observed in the transition metal ion complexes of this ligand [3]. T h e smaller shifts in these two bands seem to suggest weaker bonding of the ligand to these metal ions and this weaker bonding m a y be a result of higher coordination n u m b e r s being exhibited by the lanthanide ions.
Notes
molecules and by the tetramer equation [8] for complexes of this symmetry type. Fortran IV programs were written and used to interpret the data with a D E C System 10 computer. A g-value of 2.13 was obtained from E P R spectra and used as a constant in the least-squares fitting process. In application of the dimetallic model, only the inplane interactions between copper ions (1 and 3) and (2 and 4) are taken into account (see Fig. 1). The best fit to the dimer equation [7] dictated by the Hamiltonian, H = - 23,S 1 • S2, yields 2J = - 308 cm -1 and N a = 54 × 10 -6 cgsu. For the application of the tetrametallic model, electron spin-spin interactions among all four copper ions are taken into account. The susceptibility equation [8] for a tetrametallic system of this Jype containing four centers of s =½ is based upon a spin-only isotropic HeisenbergDirac-Van Vleck model for which the Hamiltonian is H = -23,1(S 1 • 52)-2./2(52 " S 4 - [ - 5 1 • 5 3 ) - 23,3(S1 • S 4 "~52.53) - 23-453 • S 4. The spin-spin coupling constant, J~, represents the interaction between copper ions 1 and 2, while J4 is a measure of the interaction between coppers 3 and 4. The interaction between coppers 1 and 3 is equivalent to that between coppers 2 and 4, and is represented by 3"2. The interaction between coppers 1 and 4 is equivalent to that between coppers 2 and 3 and is represented by J3. The best fit of the tetramer equation [8] to the experimental data provided the following parameters: J~ = + 8 4 c m -1, ./2 = - 1 6 3 c m -~, 3 , 3 = - 5 7 c m -1, J 4 = 0 and N a = 10 x 10 -6 cgsu. From Fig. 2 it is evident that the tetramer model provides a better fit. The overall antiferromagnetic behavior of the compound is described primarily by the in-plane coupling defined by J2. Both the sign and magnitude of 3'2 may be somewhat expected based on the 3,-value determined by the dimetallic model, where 23" = - 3 0 8 cm -~ or 3 ' = - 154 cm -~. The interaction between copper ions 1 and 2, J~, might be expected to be positive based upon the 3,-value of + 1 0 c m -1 reported for dimetallic N,N'-ethylenebis(salicylideneiminato)copper(II) [9]. This Schitt base complex has only an out-of-plane interaction which is almost identical to that described by
Jt for the title compound. On making this comparison, it is difficult to rationalize why 3,, is so much higher than about 10cm-1; and it appears that such a comparison may be an oversimplification. A J3-value of - 5 7 cm -1 is in agreement with the values of 3'1 and 3'2, and a 3,:value of zero is expected because of the rather large distance over which a superexchange mechanism would be employed. Thus it has been possible to describe the magnetic properties of acetylacetonemono (o-hydroxyanil)copper(II) by use of a tetrametallic model which takes into account all of the spin-spin interactions in the molecule.
Acknowledgements--We are grateful for the support of this research by The Robert A. Welch Foundation under Grant No. AE-491 and by Organized Research of West Texas State University. The KiUgore Reseach Center West Texas State University
M. V. H A N S O N G. D. SIMPSON W. E. M A R S H G. O. C A R L I S L E
Canyon,TX 79016 U.S.A.
REFERENCES
1. M. Kishita, Y. Muto and M. Kubo, Aust. J. Chem. 10, 386 (1957). 2. G. A. Barclay, C. M. Harris, B. F. Hoskins and E. Kokot, Proc. Chem. Soc. 264 (1961). 3. G. A. Barclay and B. F. Hoskins, J. Chem. Soc. 1979 (1965). 4. P. E. Rush, J. D. Oliver, G. D. Simpson and G. O. Carlisle, J. Inorg. Nucl. Chem. 37, 1393 (1975). 5. B. N. Figgis and R. C. Nyholm, 3'. Chem. Soc. 4190 (1958). 6. J. Lewis and R. C. Wilkins, Modem Coordination Chemistry, p. 403 Interscience, New York (1960). 7. B. Bleaney and K. D. Bowers, Proc. Roy. Soc., Set. A, 214, 451 (1952). 8. J. E. Andrew, A. B. Blake and L. R. Fraser, 3". Chem. Soc., Dalton 477 (1976). 9. G. D. Simpson, G. O. Carlisle and W. E. Hatfield, 3'. Inorg. Nucl. Chem. 36, 2257 (1974).
J, inorg, nucl. Chem. Vol. 42, pp. 140-143 © P e r g a m o n Press Ltd., 1980. Printed in Great Britain
0022-1902/80/0101-0140/$02.00/0
Thermal and electrical properties of organometaHic coordination polymers based
on centrosymmetric 1,5-naphthyridine derivatives (Received 9 April 1979) We report thermal and bulk electrical characteristics of coordination polymers based on the centrosymmetric, tetradentate ligands 4,8-dihydroxy- 1,5-naphthyridine (DHNH2) and 4,8-dithiohydroxy- 1,5-naphthyridine (DTNH2). These novel aromatic ligands are formally analogous to 8-hydroxy-quinoline (oxine). In certain cases it has been shown that the incorporation of alternating aromatic molecules into a chain of metal ions as in coordination polymers produces materials which are electrical semiconductors [1] and the current study was undertaken with this in mind.
EXPERIMENTAL
Physical measurements. Thermogravimetry was performed using an R. L. Stone T G A - 5 B Thermobalance (Cahn electrobalance) in a flowing nitrogen/oxygen atmosphere unless otherwise indicated. Samples ranging in size from 12 to 27 mg were run at a heating rate of 5°C/min. IR spectra were taken on a Beckman IR8 spectrometer using KBr pellets. X-ray powder diffraction patterns were determined on a Hayes Powder Diffractometer using filtered C u - K a radiation (A = 1.5418 A.).
Notes Conductivity m e a s u r e m e n t s were taken with a Keithley 515 M e g o h m Bridge on powder samples pressed into the form of disks. Sample disks were consistently 1 cm in dia. and between 0.9 and 1 . 1 m m thick. Contact between bridge electrodes and sample disks was facilitated by spotting the disk with either H g - - I n alloy or silver conducting paint. Resistance readings taken at ambient t e m p erature in air or in vacuo were similar, but resistances taken in air slowly decreased as the sample adsorbed water vapor. Elemental analyses were performed by Galbraith Laboratories, Knoxville, Tennessee. Preparation of D H N coordination polymers. The ligand [2] (0.31 mmol) was dissolved in warm water by addition of sodium carbonate (0.31 mmol). The warm solution was added to an a q u e o u s solution of the appropriate metal salt and after several hours the precipitate was collected on a fritted glass funnel, washed with water, and dried over P2Os in vacuo at room temperature unless otherwise indicated. Each c o m p o u n d was ground to a powder before characterization. Yields were ca. 95%. Metal salts used were C u ( O A c ) 2 . H 2 0 , Ni(NO3)z-6HzO, C0(N03)2"6 H 2 0 , M n S O a ' H 2 0 , Fe(NO3)3"9 H 2 0 , ZnCl2, CdSO4, and Pb(OAc)2'3 H 2 0 . Preparation of D T N coordination polymers. T h e ligand [2] (1 retool) was dissolved in warm D M F (dried over Linde 4 A molecular sieve) and a warm solution of transition metal acetate (1 retool) in D M F was added. After several hours the precipitate was collected on a fritted glass funnel, washed with DMF, and dried over P2Os, first at room temperature and finally at 153°C. The brittle polymers were ground to powder before characterization. Yields were roughly quantitative.
DHN, Y = O DTN, Y = S
RESULTS A N D DISCUSSION D H N polymers were prepared in aqueous solution in the presence of base. The c o m p o u n d s were isolated as the
141
hydrates whose X-ray powder diffraction patterns consisted of several diffuse bands along with lower intensity distinct bands, indicating only a low degree of crystallinity. D T N polymers were prepared in dimethyl formamide without added base. These polymers were obtained as brittle, iridescent solids whose powder diffraction patterns exhibited two highly diffuse bands. T h e C o . D T N polymer was hygroscopic, as were all the dried D H N polymers to varying degrees. Dried N i . D H N changed color from (lark brown to light green upon absorbing water from the atmosphere. Analytical data for all polymers are given in Table 1. The metal:ligand ratio was found to be 1 : 1 in all cases. The Co-DTN polymer was apparently an oligomer of low molecular weight containing dimethyl formamide. In repeated preparations of C o . D T N , the characteristic color of Co z+ was observed in the product filtrate, indicating that precipitation of Co 2+ by D T N H 2 was incomplete. The IR spectra of all the D H N polymers were similar (Table 2). It has been reported [3] that the IR spectra of the various metal oxinates are also basically identical. There is little resemblance between the oxinate spectra and those of the D H N polymers. It is difficult to compare the D H N polymer spectra with the spectrum of D H N H 2 itself because D H N H 2 probably exists as the diketo tautomer in the solid state while the D H N units in the polymers are probably formally derived from the dihydroxy tautomer. That the polymers contain chelated D H N is indicated by the loss of the finely structured band centered at 3 0 5 0 c m J, present in the spectrum of D H N H 2 and due at least partly to N - H stretching vibration. Also the strong, broad carbonyl stretching vibration at about 1545 cm 1 in the spectrum of D H N H 2 is replaced in the polymer spectra by a sharp peak at about 1500 cm- J, corresponding apparently to an aromatic ring vibration. The IR spectra of the D T N polymers also resembled one another. For reasons given above, con> parison with the spectrum of D T N H 2 is difficull. Note, however, that the D T N polymer spectra have lost both the strong band at 1 1 8 4 c m t present in the DTNH., spectrum and due to C - - S , as well as the finely strnctured N - H bands above 3000 cm- ~. None of the polymers showed any sign of melting below 300°C. T G data for all polymers are given in Table 3. Each of the D H N polymers lost water below 200°C and then decomposed in a single step to yield the metal oxide. D T N polymers decomposed in two distinct stages. This is best explained by assuming loss of ligand in the first stage
Table 1. Analytical results Calculated (%) Compound
Color
Cu'DHN.½ H 2 0 * Ni-DHN.3 H20 Co.DHN.2-½ H20 Mn-DHN-1-1 H20 FeOH.DHN.H20* Z n - D H N .3 H 2 0 * C d . D H N .3 H~O* Pb' D H N Cu.DTN? Ni-DTN§ Co. D T N II
Dark green Light green Dark brown Brown Black-violet White White White Dark green Red-brown Green
Found (%)
C
H
N
Metal
C
H
N
Metal
41.29 35.21 36.38 39.69 38.28 40.20 33.59 26.16 37.56 38.29 38.25
2.17 3.69 3.43 2.91 2.81 2.32 1.94 1.10 1.58 1.61 1.61
12.04 10.27 10.61 11.57 11.16 11.72 9.79 7.63 10.95 11.16 11.15
27.31 21.51 22.31 22.69 22.25 27.35 39.29 56.41 24.84 23.39 23.46
41.81 35.03 36.24 39.56 38.41 40.38 34.02 26.02 37.34 38.56 37.98
1.98 3.83 3.76 3.13 2.62 2.22 2.14 1.20 1.71 1.83 2.12
I 1.97 10.03 10.60 11.42 11.05 11.78 9.82 7.47 10.72 11.3t) 10.06
27.04 21.36 21.42 22.53 22.66 26.71 37.71 56.05 24.8~.: 23. !6 17.7I:
* Dried at 195°C over P2Os. -t %S. Calculated: 25.07. Found: 24.89. + D e t e r m i n e d by TG. § %S. Calculated: 25.55. Found: 25.47. II %S. Calculated: 25.53. Found: 23.14.
142
Notes Table 2. Principal IR spectral bands (v, cm 1) Compound DHNH 2 Cu.DHN'½ H20 Ni'DHN'3 H20 Co.DHN'2-½ H20 Mn.DHN. 1-½ H20 FeOH.DHN.H20 Zn-DHN -3 H20 Cd.DHN -3 H20 Pb.DHN DTNH 2 Cu.DTN Ni.DTN Co.DTN
IR 3145 m, 3050 s, 2985 m, 2950 m, 2880 m, 1545 b-vs, 1390 s, 1310m, 1187s, 1173s, 1085 m, 826s, 795m 1548 m, 1490 vs, 1430 s, 1325 m, 1265 w, 1217 s, 1000 m, 827 m, 695 w 3300 b, 1550 s, 1500 vs, 1423 s, 1322 m, 1250 m, 1218 s, 996 m, 823 m, 695 w 3300b, 1550s, 1500vs, 1420s, 1320m, 1248m, 1215s, 995 m, 821 m, 695 m 3300b, 1550s, 1502vs, 1415s, 1330m, 1243 m, 1213s, 986 m, 818 m, 695 m 3400 b-w, 1547 s, 1496vs, 1420 m, 1323 m, 1257 w, 1212m, 999 m, 823 m, 695 m 3300 b, 1550 s, 1505 vs, 1425 s, 1335 m, 1250 m, 1220 s, 993 m, 832 m, 821 m, 695 m 3300 b, 1548 s, 1502 vs, 1417 s, 1332 m, 1240 m, 1217 s, 986 m, 831m, 815 m, 695 m 1548s, 1500vs, 1425s, 1331m, 1250m, 1217m, l191s, 990 m, 847 m, 807 m, 695 m 3135m, 3100m, 3065 m, 1540s, 1515m, 1400s, 1310m, 1235m, 1213m, l184vs, 1065s, 1055s, 790s 1480 s, 1365 s, 1242 m, 1208 m, 1078 w, 829 m, 787 s, 696 m, 1485 s, 1378 m, 1250 w, 1210 s, 1080 w, 840 w, 800 s, 695 w 3400w, 3015w, 2915w, 1550w, 1485 vs, 1370s, 1243m, 1210 s, 1083 m, 825 m, 786 m, 695 m
Table 3. Results of thermogravimetric studies Weight loss (%) Compound
Ta (°C)*
Species volatilized
Cu.DHN.½ n 2 0
50-150 340-460 50-200 410-500 30-185 270-305 30-210 255-300
½H20 CsH4NzO 3 H20 CsH4N20 2½ H20 CaH4N20 2 H20 CaH4N20
FeOH.DHN-1½ H20
50-120 295-325
1½H20 CsH5N2Olo/2 )
Zn.DHN.2 H20
30-140 385-515
2 H20 CaH4N2 O
Cd.DHN.2 H20
30-155 445-540
Pb-DHN
Ni-DHN-3 H20 Co.DHN.2½ H20 Mn.DHN-2 H20
Found
Calculated
3.0 62.0 20.7 52.1 16.0 54.3 15.0 55.5
3.9 61.9 19.8 52.8 17.1 54.6 14.3 57.4
9.2 59.2
%Metalt
27.9(27.3 CuO) 21.4(21.5 NiO) 21.8(22.3 Co304) 21.3(21.9 Mn304)
10.4 58.9
21.5(21.5 Fe203)
12.4 56.4
13.8 55.1
25.0(25.0 ZnO)
2 H20 CsH4N20
10.3 46.6
11.7 46.7
34.9(36.4 CdO)
415-475
CsHaN20
38.9
39.2
55.4(56.4 PbO)
Cu.DTN
325-510 650-730
CsH4N2S S
59.8 9.2
62.6 6.3
25.1(25.1 CuO)
Ni-DTN
470-610 690-770
CsH4NzS S
56.3 15.9
63.8 6.4
21.8(23.2 NiO)
Co.DTN
30-100 200-550 710-800
(H20) CsHaN2S S
3.3 59.1 13.5
63.8 6.4
17.7(23.5 Co3Oa)
* From first significant weight loss to beginning of plateau. t Calculated values in parentheses with species weighed.
143
Notes accompanied by partial oxidation, giving a mixture of metal sulfide and metal sulfate which is then completely oxidized to the metal oxide in the second stage of decomposition. T G decomposition temperatures for the Zn z÷, Cd 2+, Pb 2+, and for the two Ni 2+ polymers, are remarkably high. Powder resistivity for all the polymers was > 1 0 ~ 2 0 h m c m ~. This may reflect the apparent low degree of crystallinity of the materials. Macrocrystals of the polymers could not be obtained by simple recrystallization since the c o m p o u n d s were highly insoluble in c o m m o n solvents.
Acknowledgement--Financial support by the Robert A. Welch Foundation and helpful conversations with Professor H. Steinfink are gratefully acknowledged.
Department of Chemistry The University of Texas at Austin Austin, T X 78712 U.S.A.
S. B. B R O W N M, J. S. D E W A R
REFERENCES 1. M. J. S. Dewar and A. M. Talati, J. Am. Chem. Soc. 86, 1592 (1964); H. Meir, Organic Semiconductors, Verlag Chemic, W e i n h e i m (1974); G. Manecke in
XXIVth International Congress of Pure and Applied Chemistry, Hamburg, Germany, 1973, Vol. 1, High Polymers, p. 155. Butterworths, London (1974). 2. S. B. Brown and M. J. S. Dewar, J. Org. Chem. 43, 1331 (1978). 3. R. G. Charles, H. Freiser, F. Friedel, L. E. Hilliard, and W. D. Johnston, Spectrochim. Acta 8, 1 (1956).
1. inorg, nucl. Chem. Vol. 42. pp. 143-145 © Pergamon Press Ltd.. 1980. Printed in Great Britain
0022-1902/80/01014)143/$02.1X)/0
2-Ethylsuifinylpyridine N-oxide complexes prepared from lanthanide(lll) perchlorates and chlorides (Received 9 May 1979) Previously [1] we c o m m u n i c a t e d o u r initial findings of only the l a n t h a n u m complex, [La(CTHgNO2S)4IC104]3, in conjunction with the nickel(II) complex of 2ethylsulfinylpyridine N-oxide (L). More recently we have reported on the transition metal ion complexes formed with 2-methylsulfinylpyridine N-oxide [2] and the title ligand [3]. Here we wish to report on the preparation and I R spectra of seven additional lanthanide complexes prepared from perchlorate salts and two solids prepared using hydrated lanthanide chlorides. A s indicated in o u r previous reports involving this ligand [1, 3], powdered microcrystilline solids can only be obtained by triturating the oils resulting from the preparative mixtures with n u m e r o u s portions of anyhydrous ether in a nitrogen atmosphere. Once formed, the solids m u s t be stored in a v a c u u m oven at 80°C while not in use. T h e partial elemental analysis of the dried solids are shown in Table 1. It is of interest to note that only the l a n t h a n u m complex was isolated free of solvent molecules. In addition, the n u m b e r of ligands per metal ion is less, excepting the p r a s e o d y m i u m solid, than the four found for lanthanum. However, the coordination n u m b e r of eight reported [1] for [LnL4](CIO4) 3 m a y be achieved for the heavier metal ions of the series by incorporation of solvent molecules in the coordination sphere. In Table 2 assignments of the I R bands pertinent to the establishment of the nature of these complexes are compiled. T h e wave n u m b e r values are assigned from spectra recorded on a B e c k m a n IR 12 as K B r disks and nujol mulls between CsI plates. The N - O stretching frequency, v N O , is shifted to lower wave n u m b e r s in all the metal complexes compared to the free ligand which is consistent with coordination of the N-oxide oxygen to metal ions [4]. It is of interest to note that the shift to lower wave n u m b e r s of 2 4 - 3 2 cm t is JINC Vol. 42, No. l--J
Table 1. Partial elemental analysis of 2ethylsulfinylpyridine N-oxide (L) complexes prepared from lanthanide(III) perchlorates and chlorides
Compound LaL4(C104)3 PrL4(H20)(CIO4)3 SmL3(CH3OH)(HzO)x (C10,)3 GdL3(CH3OH)2(CIO4)~ DyL3(CH3OH)2(CIO4)3 HoL3(CH3OH)(H20)x (C|O4)3 ErL3(CH3OH)2(C104)3 YbL~(CH3OH)z(C104)3 SmL2(CH3OH)C13 ErL2(CH3OH)CI3
Calculated C H N
C
Found H
N
29.97 3.23 4.99 29.90 3.37 4.85 29.44 3.35 4.91 29.33 3.39 4.77 26.10 3.29 4.15 26.(/3 3.55 4.22 26.73 3.41 4.07 27.35 3.50 4.48 26.60 3.40 4.05 26.63 3.50 4.48 25.73 3.24 4.09 25.59 3.75 3.96 26.48 26.33 28.54 27.80
3.38 3.36 3.52 3.42
4.03 4.01 4.44 4.32
26.20 26.50 28.61 28.16
3.43 3.74 3.45 3.37
4.07 4.31 4.34 4.40
s o m e w h a t less than the shift observed for divalent transition metal ions, 3 2 - 4 2 cm 1, and considerably less than the 4 4 - 4 9 cm -1 range found for the trivalent transition metal ions of this ligand. Similarly, vSO is shifted to lower wave n u m b e r s in the lanthanide complexes when compared to the free ligand confirming that it is also b o u n d to the lanthanide ion via oxygen [5]. Again the shift is somewhat less than observed in the transition metal ion complexes of this ligand [3]. T h e smaller shifts in these two bands seem to suggest weaker bonding of the ligand to these metal ions and this weaker bonding m a y be a result of higher coordination n u m b e r s being exhibited by the lanthanide ions.