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Complexes of tetramethyl- and tetraethyldithiooxamide with zinc(II), cadmium(II) and mercury(II)
J. inorg, nucl. C/lem., 1974, Vol. 36, pp. 1751 1754.Pergamon Press. Printed in Great Britain.
COMPLEXES OF TETRAMETHYL- A N D TETRAETHYLDITHIOOXAMIDE WITH ZINC(II), CADMIUM(II) A N D MERCURY(II) A N T O N I O C. FABRETTI, G I A N C A R L O P E L L A C A N I and G I O R G I O P E Y R O N E L lstituto di Chimica Generale e lnorganica, University of Modena, 41100 Modena, Italy (Receilcd 18 Mat" 1973) Abstract With tetramethyl- (MeaD) and tetraethyl-dithiooxamide (EtaD) zinc(IlL cadmium(ll) and mercurylll) form IMLX2] iX = CI, Br, 1) complexes (which are non-electrolytes) and [ML3](CIOa) 2 complexes (which are 1:2 electrolytes). The i.r. v(CN) and v(CS) bands of the ligands are shifted in the complexes to higher and lower frequencies respectively, in agreement with a sulpht~r-coordination of the ligand to the metal: v{MS) bands are observed at frequencies higher for the MEAD- than for the EtaDcomplexes, indicating that MeaD is a stronger ligand than Et4D. The observed metal halogen stretching frequencies indicate that Z n L X 2 complexes are tetrahedral, HgLX 2 complexes may be considered effectively four coordinate, while the CdLX2 complexes are octahedral through halogen bridging. The complex iHglMeaD)3](C1Oa)2 shows three i.r. bands of the free ligand besides the same bands shifted by complexation, as in the other complexes. This may indicate that in this complex only part of the R z , N - - C = S groups are sulphur-coordinated to the metal leading to a lower, presumably tetrahedral, coordination.
INTRODUCTION
WITH the first t r a n s i t i o n series m e t a l s , f r o m m a n ganese(II) to copper(ll), t e t r a m e t h y l - a n d t e t r a e t h y l d i t h i o o x a m i d e f o r m o c t a h e d r a l M L 3 A 2 (A = C104, FeCI,,), Cu(MeaD)2(C1Oa)2, C u L X 2 (X = C1, Br) S,Sc o o r d i n a t e d c o m p l e x e s [ l ] . Since d i v a l e n t zinc, cadm i u m a n d m e r c u r y ions c a n f o r m c o m p l e x e s with v a r i o u s g e o m e t r i e s , a n d c o m p l e x e s o f t h e s e m e t a l s with" t e t r a m e t h y l - (Me,,D) a n d t e t r a e t h y l - d i t h i o o x a m i d e (EtaD) are u n k n o w n , t h e y h a v e been investigated.
EXPERIMENTAL Both the ligands were prepared by the method described by Hurd el al. for tetraethyldithiooxamide[2]. All reagents were of the best chemical grade. Acid used : HAc (glacial), HCI (37",,), HBr (481',d, HI (571',,), HCIOa {60,,,). The complexes were prepared by adding a metal salt solution to a ligand (L) solution in the following solvents (acetic acid = HAc, methylcellosolve = MCS) and ratios. Zn(MegD)X 2 IX = CI, Br, 1): 1 m M Z n X z in 20 ml HAc to I m M L in 20 ml HAc: Zn(Et,~D)X z (X = CI, Br, I): I m M Z n X z in 10 ml HAc to l m M L in 10 ml HAc: Zn(EtaDJ3(CIOa)2 : 6 m M ZnAc 2 in 10 ml HAc + 5 ml HCIO a to 2 m M L in 10 ml HAc: Cd(MeaD)I2 : I m M CdI 2 in 3 ml MCS to 2 m M L in 3 ml MCS: Cd(MeaDI3(CIO,02:2 m M CdAc2 in 10 ml HAc + 5 ml H C I O a t o 2 m M L i n lOml HAc:Cd(Et,tDIBr2 : 2mMCdAc, in6mlHActo4mMLin20mlHAc + l ml HBr: Cd(EL, D)I2 : 3 m M Cdl 2 in 6 ml MCS to 2 m M L in 6 ml MCS + 1 ml HBr: Cd(Et4D)3(CIO,,)2 : 3 m M CdAc2 in 12 ml HC10 a to 4 m M L in 40 ml HAc: Hg{MegD)X 2 and Hg(EL.D)X 2 (X = CI, Brt: 2 m M HgAc2 in 5 ml HX to
4 ml L in 20 ml HAc: Hg(Me4D)I2:2 m M Hgl 2 in 10 ml MCS to 3 m M L in 8 ml M C S Hg(Me4Dts(CIO,02 : 1 mM HgAc z in 3ml HCIO 4 to 2 m M L in 15 ml HAc : Hg(Et4DJl 2 : 1 m M HgIg in 5 ml MCS to I m M L in 5 ml MCS: HgIEtaD)3(CIO.~) 2 : 2 m M HgAc 2 in 5 ml HCIO 4 to 4 mM L in 20 ml HAc. The c o m p o u n d s may be washed with the same solvent, HAc or MCS, from which they were precipitated, and with ethyl ether: all are soluble in D M F and most of them in acetone. Analytical determinations were performed as follows: zinc by EDTA titration, cadmium as CdNHgPO,~, mercury as sulphide, sulphur as BaSOa, carbon by combustion, chlorine in the Zn- and Cd-complexes by Volhard titration and in the Hg-complexes ponderally as AgCI. Analytical resuhs are given in Table I. Conductivities (Table I I were measured with a W T W conductivity bridge at 25°C. [.R. spectra (Table 2) were recorded with a Perkin-Elmer 521 spectrophotometer on KBr pelletts (4000-250 cm ~) or on nujol mulls on polythene (600-250 cm 11 and with a Perkin Elmer F'IS3 spectrophotometer on nujol mulls on polythene (400-60 c m - 1).
RESULTS AND D I S C U S S I O N
With tetramethyl- and tetraethyl-dithiooxamide zinc(II), c a d m i u m ( I 1 ) a n d m e r c u r y ( I I ) f o r m c o m p l e x e s of s t o i c h i o m e t r y [ M L X 2 ] (X = CI, Br, I) w h i c h b e h a v e as n o n - e l e c t r o l y t e s (AM = 4 - 2 3 in D M F or acetone) a n d [ML31(C1Oa) 2 w h i c h are 1 : 2 electrolytes (AM = 150-181 in D M F ) . Between 4000 a n d 500 c m - t t h e i.r. s p e c t r a of t h e c o m p l e x e s a r e very s i m i l a r to t h o s e of their ligand.
1751
1752
ANTONIOC. FABRETTI,GIANCARLOPELLACANIand GIORGIOPEYRONEL
Table 1. Analytical data, found !',, and Icalcd !'ot: molar conductivity AM (~-~. mole -~ .cm 2) in 10 3 M acetone solution L = Me4 D
Colour
Yield i',,
ZnLCI z ZnLBr 2 ZnLI2 CdLI 2 CdLa(CIO4) 2 HgLCI a HgLBr z HgLI 2 HgL~(CIO4J2
white white yellow white pale yellow white white pale yellow yellow
90 100 86 90 50 100 80 90 80
20.87(20.92) 16-21( 16.29t 13-13(13.19) 20.49(20.72) 13.21(13.38) 44.90(44.80) 37.61(37-37) 31-61(31.80t 21-77(21.61)
pale yellow pale yellow pale yellow white pale yellow white white yellow dark yellow yellow yellow
40 40 70 10 80 50 50 70 90 70 10
17.76(17.74) 14.27(14.29) 11.88(11.85) 6.84 (6.80) 21.94(22.28) 18.42(18.781 10.84(11.15) 39.94(39.81) 33.92(33.84t 29.60(29.21) 17.55(18.29)
L= Et4D ZnLCI2 ZnLBr 2 ZnLI 2 ZnL3(CIO,,) 2
CdLBr a CdLI 2 CdL3(CIO,,)2 HgLCI z HgLBr 2 HgLI 2 HgL3(CIO#)2
M
According to the assignments given by Scott and Wagner[3] for the dithiooxamide and by Gosavi, Agarwala and Rao[4] for other thioamidic ligand i.r. spectra, the band at 1528 cm-1 for Me4D and 1498 c m - ~ for Et4D are principally due to v(CN), and those at 828 c m - 1 for Me4D and 869 c m - t for Et,~D to v(CS) vibrations. In the complexes these bands are shifted to higher frequencies for the v(CN) bands (1555-1565 c m - a for Me4D and 1520-1565 c m - ~ for Et4D) and to lower frequencies for the v(CS) bands (815-820 c m - 1 for Me4D and 855-860 c m - ~ for Et4D) indicating an increase in the C - N and a decrease in the C - S doublebond character owing to a sulphur coordination of the ligands to the metal : R 2Nr'~C--S~-~ Me. J
The far i.r. spectra of the complexes confirm this coordination. Two new bands at 330-350 and 320-340 cm-~ for the Me4D-complexes and at 300-320 c m and 250-275 cm-1 for the Et4D-complexes may be assigned to v(M-S) modes. Two bands are consistent with symmetric and antisymmetric M - S stretching vibrations[5]. In the non-electrolyte MLX2 complexes the halogen atoms are coordinated to the metal. Most of the ZnLX 2 complexes distinctly show two v(ZnX) bands in agreement with a tetrahedral symmetry[6]; the observed v(ZnX) frequencies are consistent with other values given for non-bridged halogen-metal bonds in a Ta symmetry : The v(ZnBr)/v(ZnCl) and v(Znl)/v(ZnCl) ratios agree well with those cited for tetrahedral anions MX~ (6) (0.77 and 0.65).
S
C
10 - 3
M DMF and (*) CI
23.04(23.04t 18.60(17.93) 14.30(14.53) 13.71(13.27) 22.82(22.90) 14.88(14.33) 11.92111.95J 10-15(10.17t 20-68t20.73)
20.02(20.02) 12.23(12.71) 10.81(10.72) 19.00(19.08) 13.26(12.73) 10.84(10.821 9-34 O.34~ 18-08(18.05)
8.23 (8.44) 16.05(15.84)
33.00(32.56) 26.63(26.23) 21.69(21.76) 8.09 (7.37) 7-18 (7.03) 14.14114.07) 6.29 (6.46)
AM 6 9 5* 21 161 6 7 4 181 6 8 4* 150 20 23 151 5 5 4 151
The observed v(CdX) frequencies agree with those given for other complexes postulated as being octahedral with halide bridging : A weakened bridging interaction [8] may be responsible for the higher v(Cdl) values observed in both the complexes and which are closer to the v(CdBr) values. The observed v(HgX) frequencies are consistent with an effective four-coordination of the metal. It is remarkable that all the v(MS) frequencies are higher for the Me4D- than for the Et4D-complexes while the opposite is true of the v(MX) frequencies. This may be due[10] to the different basicity (1) Me4D > Et4D of the ligands. The ratios v(HgX)/ v(HgCl) observed for the complexes HgX 2 . L (L = Me4D, Et4D) well agree with those observed in other complexes[7-9, 11]. In all ML3(C104) 2 complexes perchlorate ions are not coordinated, as is shown by their observed v3, Vl and v4 bands (Table 2) which correspond very well to those given[12] for the Ta ion : 1119, 928 and 625 c m - 1. in the Hg(Me4D)3(CIOg)z complex three bands of the ligand are split into two bands: one having the frequency observed for the ligand, the other the frequency observed for the other complexes : The splitting of these three bands indicates that in the Hg(Me,,D)3(C104) 2 complex only part of the R 2 N - - C = S groups are S-bonded to the metal as in the other complexes while another part is uncoordinated. This may signify that either one Me,,D molecule is uncoordinated in a tetrahedral complex [Hg(MegD)2]. Me4D(C104)2 or that only one MegD molecule is bicoordinated while the other two act as monodentate ligands in a deformed tetrahedral structure ; lattice site inequalities may also be possible.
1753
Complexes of MeaD and EtaD with Zn(ll), Cd(ll) and Hg(ll) Table 2. Principal infrared bands (cm - L)
CIO~ bands
1. = Me4D ZnLCI2 ZnLBr, ZnLI 2 Cdl.I 2 CdL3ICIOJ2 HgLCI2 HgLBr2
HgLI2 HgL3IC10,d ~ L = Et.;D
ZnI.CI 2 ZnLBr
e
ZnLI2 ZnL.,,(C104)2 CdLBr2 CdL[ 2 CdL3(CIO.,)2 HgLCI2 HgLBrz Hgl.12 Hgl..dCIO~L,
v(CN)
v(CS)
v(MS)
1528vs 1565vsb 1565vsb 1555vsb 1560vsb 1560vsb 1555vsb 1563vs 1550vsb 1560sh. 1545sh
828m 820s 822s 81% 818s 817s 815s 816s 813s 816ms
352s, 339s 351s. 336s 349s, 336s 341ms. 328ms 341ms. 326sh 347m. 333ms 341 ms. 326ms 332mw. 319mw 345mb
1498vs 1564 1550vs 1553vsb 1550vsb 1548vs. 1500sh 1547vs, 1525sh 1520vs 1545vs, 1498sh 1550vs, 1510s 1548¥s, 1515s 1520vsb 1530vsb
869m 855m 853m 854m 858m 857m 854m 860m 858m 858m 858m 862ms
298m,
247w
298w,
252m
332, 308 331,323 326, 293 307, 289 332
v(HgCl) HgX 2 . bipyridyl[8] HgX 2 . pyridine N-oxyde[9] HgX 2 . pyrazine[7] HgX 2 . pyrimidine[7] HgX z . Me, D (this work) HgX2. Et4D (this work)
270 300 254 263 240 297
U4
628vs
ll00vsb
ll00vsb
938mw
625s
332vsb 258vsb 219vs, 184vs 1085vsb
623s
1090vsb
622s
1090vsb
628vs
205s 172s 297s 198s, 184s 161s
v(Znl)
vIZnBrl
v(ZnCl) 0.73 0.78 0-80 0.79 0-78
0-65 0.64 0.66 0.66
vICdBr)
vICdl)
186 205 176 167, t50
142
viHgBr) v(HgCI)
vIZnll
vIZnCl)
244 260, 252 260, 254 242, 233 258
205
0.70 0-80 0.82 0.78 0-72 0.67
VI
240vsb 173s 146ms
vlZnBr)
CdX 2 . pyrazine[7] CdX 2 . pyrimidine[7] CdX_,. pyridazine[7] C d X z . bipyridyl[8] CdX 2 . Me4D 1this work) C d X 2 . Et,~D {this workl
~'3
307vs. 289vs 242vs. 233vs 204vs, 196sh 172s
1292ms1 305vsb, 270sh 305vsb. 276sh 305vsb. 274s 298mw, 260msb 308m. 260vw 304m, 260w 297mw, 260sb 318sh 312m
v~ZnCl) ZnX 2 . pyridazine[7] Z n X 2 . bipyridyl[8] Z n X 2 . 2 pyridine[81 Z n X 2 . Me4D (this work) ZnX 2 . Et4D [this work)
v[MXI
215, 196 210 204, 196 219, 184
157.149 172 172
vIHgBr) 190 240 208 205 173 198,184
v(Hgll v{HgCl)
v(Hgl)
0.60
162,142
0.61 0.54
146 161
1754
ANTONIO C. FABRETT1,GIAN CARLOPELLACANIand GIORGIO PEYRONEL
Me~,D
1528vs 989s
HglMe,,DI3(CIO,d 2
--* ~
573ms ~
1560sh 1545sh 1530s 982ms 965ms 572sh 562ms
The other complexes ~
1550 1565vsb
~
965-970s
~
562 568s
It has been shown[l] that Me4D is a stronger ligand than Et4D. This is demonstrated, also in these complexes, by the v(MS) frequencies being higher for the Me4D- than for the Et4D-complexes. In the case of the Hg(ClO,,)2-complexes, the higher coordination energy of Me~D could be responsible for a more compact coordination in the Hg(Me4D)3(C104)2 complex as against a more relaxed (deformed octahedral?) coordination of the Et,,D-complex.
Acknowledgement--This work has,been supported by a financial aid of the Consigfio Nazionale delle Ricerche of Italy.
REFERENCES
I. G. Peyronel, G. C. Pellacani, A. Pignedoli and G. Benetti, lnorg. Chim. Acta 5, 263 (1971). 2. R. N. Hurd, G. De La Mater, G. C. McElheny and L. V. Peiffer, J. Am. c/wm. Soc. 82, 4454 (1960). 3. J. A. Scott and E. L. Wagner, I. chem. Phys. 10, 465 (1958). 4. R. K. Gosavi, U. Agarwala and C. N. R. Rao, J. Am. chem. Soc. 89, 235 (1967). 5. J. R. Ferraro, Low-Frequen~ 3' Vibrations qf Inorganic and Coordination CompoumLs-, p. 248. Plenum Press, New York (1971). 6. R. J. H. Clark and C. S. Williams, lm,g. Chem. 4, 350 (1965). 7. J. R. Ferraro, W. Wozniak and G. Roch, Ricerca scient. 38, 433 (1968). 8. J. E. Douglas and C. J. Wilkins, hTorg. Chim. Acta 3, 635 (1969). 9. 1. S. Ahuja and P. Rast.ogi, J. chem. Soc. (A), 378 (1970). 10. S. C. ,lain and R. Rivest, h~org. Chim. Acta 3, 552 (1969). l l. G. B. Deacon, J. H. S. Green and D. J. Harrison, Spectrochim. Acta 24A, 1921 (1968). 12. K. Nakamoto, lnfi'ared Spectra qf Inorganic and Coordination Compounds, p. 11 I, Wiley-lnterscience, New York (1970).
COMPLEXES OF TETRAMETHYL- A N D TETRAETHYLDITHIOOXAMIDE WITH ZINC(II), CADMIUM(II) A N D MERCURY(II) A N T O N I O C. FABRETTI, G I A N C A R L O P E L L A C A N I and G I O R G I O P E Y R O N E L lstituto di Chimica Generale e lnorganica, University of Modena, 41100 Modena, Italy (Receilcd 18 Mat" 1973) Abstract With tetramethyl- (MeaD) and tetraethyl-dithiooxamide (EtaD) zinc(IlL cadmium(ll) and mercurylll) form IMLX2] iX = CI, Br, 1) complexes (which are non-electrolytes) and [ML3](CIOa) 2 complexes (which are 1:2 electrolytes). The i.r. v(CN) and v(CS) bands of the ligands are shifted in the complexes to higher and lower frequencies respectively, in agreement with a sulpht~r-coordination of the ligand to the metal: v{MS) bands are observed at frequencies higher for the MEAD- than for the EtaDcomplexes, indicating that MeaD is a stronger ligand than Et4D. The observed metal halogen stretching frequencies indicate that Z n L X 2 complexes are tetrahedral, HgLX 2 complexes may be considered effectively four coordinate, while the CdLX2 complexes are octahedral through halogen bridging. The complex iHglMeaD)3](C1Oa)2 shows three i.r. bands of the free ligand besides the same bands shifted by complexation, as in the other complexes. This may indicate that in this complex only part of the R z , N - - C = S groups are sulphur-coordinated to the metal leading to a lower, presumably tetrahedral, coordination.
INTRODUCTION
WITH the first t r a n s i t i o n series m e t a l s , f r o m m a n ganese(II) to copper(ll), t e t r a m e t h y l - a n d t e t r a e t h y l d i t h i o o x a m i d e f o r m o c t a h e d r a l M L 3 A 2 (A = C104, FeCI,,), Cu(MeaD)2(C1Oa)2, C u L X 2 (X = C1, Br) S,Sc o o r d i n a t e d c o m p l e x e s [ l ] . Since d i v a l e n t zinc, cadm i u m a n d m e r c u r y ions c a n f o r m c o m p l e x e s with v a r i o u s g e o m e t r i e s , a n d c o m p l e x e s o f t h e s e m e t a l s with" t e t r a m e t h y l - (Me,,D) a n d t e t r a e t h y l - d i t h i o o x a m i d e (EtaD) are u n k n o w n , t h e y h a v e been investigated.
EXPERIMENTAL Both the ligands were prepared by the method described by Hurd el al. for tetraethyldithiooxamide[2]. All reagents were of the best chemical grade. Acid used : HAc (glacial), HCI (37",,), HBr (481',d, HI (571',,), HCIOa {60,,,). The complexes were prepared by adding a metal salt solution to a ligand (L) solution in the following solvents (acetic acid = HAc, methylcellosolve = MCS) and ratios. Zn(MegD)X 2 IX = CI, Br, 1): 1 m M Z n X z in 20 ml HAc to I m M L in 20 ml HAc: Zn(Et,~D)X z (X = CI, Br, I): I m M Z n X z in 10 ml HAc to l m M L in 10 ml HAc: Zn(EtaDJ3(CIOa)2 : 6 m M ZnAc 2 in 10 ml HAc + 5 ml HCIO a to 2 m M L in 10 ml HAc: Cd(MeaD)I2 : I m M CdI 2 in 3 ml MCS to 2 m M L in 3 ml MCS: Cd(MeaDI3(CIO,02:2 m M CdAc2 in 10 ml HAc + 5 ml H C I O a t o 2 m M L i n lOml HAc:Cd(Et,tDIBr2 : 2mMCdAc, in6mlHActo4mMLin20mlHAc + l ml HBr: Cd(EL, D)I2 : 3 m M Cdl 2 in 6 ml MCS to 2 m M L in 6 ml MCS + 1 ml HBr: Cd(Et4D)3(CIO,,)2 : 3 m M CdAc2 in 12 ml HC10 a to 4 m M L in 40 ml HAc: Hg{MegD)X 2 and Hg(EL.D)X 2 (X = CI, Brt: 2 m M HgAc2 in 5 ml HX to
4 ml L in 20 ml HAc: Hg(Me4D)I2:2 m M Hgl 2 in 10 ml MCS to 3 m M L in 8 ml M C S Hg(Me4Dts(CIO,02 : 1 mM HgAc z in 3ml HCIO 4 to 2 m M L in 15 ml HAc : Hg(Et4DJl 2 : 1 m M HgIg in 5 ml MCS to I m M L in 5 ml MCS: HgIEtaD)3(CIO.~) 2 : 2 m M HgAc 2 in 5 ml HCIO 4 to 4 mM L in 20 ml HAc. The c o m p o u n d s may be washed with the same solvent, HAc or MCS, from which they were precipitated, and with ethyl ether: all are soluble in D M F and most of them in acetone. Analytical determinations were performed as follows: zinc by EDTA titration, cadmium as CdNHgPO,~, mercury as sulphide, sulphur as BaSOa, carbon by combustion, chlorine in the Zn- and Cd-complexes by Volhard titration and in the Hg-complexes ponderally as AgCI. Analytical resuhs are given in Table I. Conductivities (Table I I were measured with a W T W conductivity bridge at 25°C. [.R. spectra (Table 2) were recorded with a Perkin-Elmer 521 spectrophotometer on KBr pelletts (4000-250 cm ~) or on nujol mulls on polythene (600-250 cm 11 and with a Perkin Elmer F'IS3 spectrophotometer on nujol mulls on polythene (400-60 c m - 1).
RESULTS AND D I S C U S S I O N
With tetramethyl- and tetraethyl-dithiooxamide zinc(II), c a d m i u m ( I 1 ) a n d m e r c u r y ( I I ) f o r m c o m p l e x e s of s t o i c h i o m e t r y [ M L X 2 ] (X = CI, Br, I) w h i c h b e h a v e as n o n - e l e c t r o l y t e s (AM = 4 - 2 3 in D M F or acetone) a n d [ML31(C1Oa) 2 w h i c h are 1 : 2 electrolytes (AM = 150-181 in D M F ) . Between 4000 a n d 500 c m - t t h e i.r. s p e c t r a of t h e c o m p l e x e s a r e very s i m i l a r to t h o s e of their ligand.
1751
1752
ANTONIOC. FABRETTI,GIANCARLOPELLACANIand GIORGIOPEYRONEL
Table 1. Analytical data, found !',, and Icalcd !'ot: molar conductivity AM (~-~. mole -~ .cm 2) in 10 3 M acetone solution L = Me4 D
Colour
Yield i',,
ZnLCI z ZnLBr 2 ZnLI2 CdLI 2 CdLa(CIO4) 2 HgLCI a HgLBr z HgLI 2 HgL~(CIO4J2
white white yellow white pale yellow white white pale yellow yellow
90 100 86 90 50 100 80 90 80
20.87(20.92) 16-21( 16.29t 13-13(13.19) 20.49(20.72) 13.21(13.38) 44.90(44.80) 37.61(37-37) 31-61(31.80t 21-77(21.61)
pale yellow pale yellow pale yellow white pale yellow white white yellow dark yellow yellow yellow
40 40 70 10 80 50 50 70 90 70 10
17.76(17.74) 14.27(14.29) 11.88(11.85) 6.84 (6.80) 21.94(22.28) 18.42(18.781 10.84(11.15) 39.94(39.81) 33.92(33.84t 29.60(29.21) 17.55(18.29)
L= Et4D ZnLCI2 ZnLBr 2 ZnLI 2 ZnL3(CIO,,) 2
CdLBr a CdLI 2 CdL3(CIO,,)2 HgLCI z HgLBr 2 HgLI 2 HgL3(CIO#)2
M
According to the assignments given by Scott and Wagner[3] for the dithiooxamide and by Gosavi, Agarwala and Rao[4] for other thioamidic ligand i.r. spectra, the band at 1528 cm-1 for Me4D and 1498 c m - ~ for Et4D are principally due to v(CN), and those at 828 c m - 1 for Me4D and 869 c m - t for Et,~D to v(CS) vibrations. In the complexes these bands are shifted to higher frequencies for the v(CN) bands (1555-1565 c m - a for Me4D and 1520-1565 c m - ~ for Et4D) and to lower frequencies for the v(CS) bands (815-820 c m - 1 for Me4D and 855-860 c m - ~ for Et4D) indicating an increase in the C - N and a decrease in the C - S doublebond character owing to a sulphur coordination of the ligands to the metal : R 2Nr'~C--S~-~ Me. J
The far i.r. spectra of the complexes confirm this coordination. Two new bands at 330-350 and 320-340 cm-~ for the Me4D-complexes and at 300-320 c m and 250-275 cm-1 for the Et4D-complexes may be assigned to v(M-S) modes. Two bands are consistent with symmetric and antisymmetric M - S stretching vibrations[5]. In the non-electrolyte MLX2 complexes the halogen atoms are coordinated to the metal. Most of the ZnLX 2 complexes distinctly show two v(ZnX) bands in agreement with a tetrahedral symmetry[6]; the observed v(ZnX) frequencies are consistent with other values given for non-bridged halogen-metal bonds in a Ta symmetry : The v(ZnBr)/v(ZnCl) and v(Znl)/v(ZnCl) ratios agree well with those cited for tetrahedral anions MX~ (6) (0.77 and 0.65).
S
C
10 - 3
M DMF and (*) CI
23.04(23.04t 18.60(17.93) 14.30(14.53) 13.71(13.27) 22.82(22.90) 14.88(14.33) 11.92111.95J 10-15(10.17t 20-68t20.73)
20.02(20.02) 12.23(12.71) 10.81(10.72) 19.00(19.08) 13.26(12.73) 10.84(10.821 9-34 O.34~ 18-08(18.05)
8.23 (8.44) 16.05(15.84)
33.00(32.56) 26.63(26.23) 21.69(21.76) 8.09 (7.37) 7-18 (7.03) 14.14114.07) 6.29 (6.46)
AM 6 9 5* 21 161 6 7 4 181 6 8 4* 150 20 23 151 5 5 4 151
The observed v(CdX) frequencies agree with those given for other complexes postulated as being octahedral with halide bridging : A weakened bridging interaction [8] may be responsible for the higher v(Cdl) values observed in both the complexes and which are closer to the v(CdBr) values. The observed v(HgX) frequencies are consistent with an effective four-coordination of the metal. It is remarkable that all the v(MS) frequencies are higher for the Me4D- than for the Et4D-complexes while the opposite is true of the v(MX) frequencies. This may be due[10] to the different basicity (1) Me4D > Et4D of the ligands. The ratios v(HgX)/ v(HgCl) observed for the complexes HgX 2 . L (L = Me4D, Et4D) well agree with those observed in other complexes[7-9, 11]. In all ML3(C104) 2 complexes perchlorate ions are not coordinated, as is shown by their observed v3, Vl and v4 bands (Table 2) which correspond very well to those given[12] for the Ta ion : 1119, 928 and 625 c m - 1. in the Hg(Me4D)3(CIOg)z complex three bands of the ligand are split into two bands: one having the frequency observed for the ligand, the other the frequency observed for the other complexes : The splitting of these three bands indicates that in the Hg(Me,,D)3(C104) 2 complex only part of the R 2 N - - C = S groups are S-bonded to the metal as in the other complexes while another part is uncoordinated. This may signify that either one Me,,D molecule is uncoordinated in a tetrahedral complex [Hg(MegD)2]. Me4D(C104)2 or that only one MegD molecule is bicoordinated while the other two act as monodentate ligands in a deformed tetrahedral structure ; lattice site inequalities may also be possible.
1753
Complexes of MeaD and EtaD with Zn(ll), Cd(ll) and Hg(ll) Table 2. Principal infrared bands (cm - L)
CIO~ bands
1. = Me4D ZnLCI2 ZnLBr, ZnLI 2 Cdl.I 2 CdL3ICIOJ2 HgLCI2 HgLBr2
HgLI2 HgL3IC10,d ~ L = Et.;D
ZnI.CI 2 ZnLBr
e
ZnLI2 ZnL.,,(C104)2 CdLBr2 CdL[ 2 CdL3(CIO.,)2 HgLCI2 HgLBrz Hgl.12 Hgl..dCIO~L,
v(CN)
v(CS)
v(MS)
1528vs 1565vsb 1565vsb 1555vsb 1560vsb 1560vsb 1555vsb 1563vs 1550vsb 1560sh. 1545sh
828m 820s 822s 81% 818s 817s 815s 816s 813s 816ms
352s, 339s 351s. 336s 349s, 336s 341ms. 328ms 341ms. 326sh 347m. 333ms 341 ms. 326ms 332mw. 319mw 345mb
1498vs 1564 1550vs 1553vsb 1550vsb 1548vs. 1500sh 1547vs, 1525sh 1520vs 1545vs, 1498sh 1550vs, 1510s 1548¥s, 1515s 1520vsb 1530vsb
869m 855m 853m 854m 858m 857m 854m 860m 858m 858m 858m 862ms
298m,
247w
298w,
252m
332, 308 331,323 326, 293 307, 289 332
v(HgCl) HgX 2 . bipyridyl[8] HgX 2 . pyridine N-oxyde[9] HgX 2 . pyrazine[7] HgX 2 . pyrimidine[7] HgX z . Me, D (this work) HgX2. Et4D (this work)
270 300 254 263 240 297
U4
628vs
ll00vsb
ll00vsb
938mw
625s
332vsb 258vsb 219vs, 184vs 1085vsb
623s
1090vsb
622s
1090vsb
628vs
205s 172s 297s 198s, 184s 161s
v(Znl)
vIZnBrl
v(ZnCl) 0.73 0.78 0-80 0.79 0-78
0-65 0.64 0.66 0.66
vICdBr)
vICdl)
186 205 176 167, t50
142
viHgBr) v(HgCI)
vIZnll
vIZnCl)
244 260, 252 260, 254 242, 233 258
205
0.70 0-80 0.82 0.78 0-72 0.67
VI
240vsb 173s 146ms
vlZnBr)
CdX 2 . pyrazine[7] CdX 2 . pyrimidine[7] CdX_,. pyridazine[7] C d X z . bipyridyl[8] CdX 2 . Me4D 1this work) C d X 2 . Et,~D {this workl
~'3
307vs. 289vs 242vs. 233vs 204vs, 196sh 172s
1292ms1 305vsb, 270sh 305vsb. 276sh 305vsb. 274s 298mw, 260msb 308m. 260vw 304m, 260w 297mw, 260sb 318sh 312m
v~ZnCl) ZnX 2 . pyridazine[7] Z n X 2 . bipyridyl[8] Z n X 2 . 2 pyridine[81 Z n X 2 . Me4D (this work) ZnX 2 . Et4D [this work)
v[MXI
215, 196 210 204, 196 219, 184
157.149 172 172
vIHgBr) 190 240 208 205 173 198,184
v(Hgll v{HgCl)
v(Hgl)
0.60
162,142
0.61 0.54
146 161
1754
ANTONIO C. FABRETT1,GIAN CARLOPELLACANIand GIORGIO PEYRONEL
Me~,D
1528vs 989s
HglMe,,DI3(CIO,d 2
--* ~
573ms ~
1560sh 1545sh 1530s 982ms 965ms 572sh 562ms
The other complexes ~
1550 1565vsb
~
965-970s
~
562 568s
It has been shown[l] that Me4D is a stronger ligand than Et4D. This is demonstrated, also in these complexes, by the v(MS) frequencies being higher for the Me4D- than for the Et4D-complexes. In the case of the Hg(ClO,,)2-complexes, the higher coordination energy of Me~D could be responsible for a more compact coordination in the Hg(Me4D)3(C104)2 complex as against a more relaxed (deformed octahedral?) coordination of the Et,,D-complex.
Acknowledgement--This work has,been supported by a financial aid of the Consigfio Nazionale delle Ricerche of Italy.
REFERENCES
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