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Lipophilic technetium complexes—VII. Neutral oxotechnetium(V) complexes of tridentate Schiff-bases containing monothioles as co-ligands
A&. Radial. Isor. Vol. 41, No. 2, pp. 185-188, Inl. J. Radiat. Appl. Instrum. Part A Printed in Great Britain. All rights reserved
1990 Copyright
0883-2889/90 $3.00 + 0.00 cs 1990 Pergamon Press plc
Lipophilic Technetium Complexes-VII. Neutral Oxotechnetium(V) Complexes of Tridentate Schiff-bases Containing Monothioles as Co-ligands H.-J. PIETZSCH,’ ‘Central
Institute
H. SPIES,‘*
S. HOFFMANN’
and
D. SCHELLER’
of Nuclear Research, Rossendorf 8051 Dresden, Postfach 19 and ‘Dresden University of Technology, Dresden, G.D.R.
(Received
20 February
1989; in revised form 26 April 1989)
Five-coordinate oxotechnetium(V) complexes TcOL(SR), where H,L = Schiff-bases N-salicylidene-2aminothiophenole (H,salabt), N-acetylacetone-2-aminothiophenole (H,acacabt) or N-salicylidene-2aminophenole (H,sap) and R-SH = thiophenoles, mercaptanes or 2-mercaptoacetic acid ethylester, are prepared by the reaction of tetrachlorooxotechnetate(V) or Tc(V) gluconate with a I:1 mixture of the appropriate tridentate/monodentate ligands. The products are characterized by elemental analysis, u.v.-vis, i.r. and ‘H-NMR spectroscopy. The compounds represent the first Schiff-base complexes of Tc(V) which contain monodentate thioles as co-ligands.
Introduction Recently we were able to achieve synthesis of neutral, small-sized Tc complexes TcO(SXS)(SR) by joint action of dianionic tridentate ligands HSXSH and monodentate thiole ligands R-SH on appropriate oxotechnetium(V) precursors (Pietzsch et al., 1989a,b) and suggest that this method could be a general approach to new neutral Tc complexes (Spies and Pietzsch, 1988). The continuing interest in the design of neutral Tc complexes and our own desire to exploit the full chemistry range of the Tc compounds based on 3 + 1 donor ligand combinations encouraged us to involve tridentate Schiff-bases, in combination with monothioles, to synthesize neutral oxotechnetium(V) complexes. As reported earlier by Bandoli et al. (1984) and Tisato et al. (1987), tridentate Schiff-bases provide a variety of Tc=O complexes including those with additional, preferably bidentate, co-ligands. Thus, the reaction of the tridentate Schiff-bases N-salicylidene-2-aminothioor N-salicylidene-2-aminophenole (Hz salabt) phenole (H,sap) with TcOCl; gives TcOLCl. Mixed complexes of the formulation TcOLL*, where L2 = bidentate Schiff-base anions or quinolin-8-01, were obtained by the subsequent reaction of TcOLCl with those bidentate ligands. Reaction of 2-(2-
*Author for correspondence
hydroxyphenyl)benzothiazohne with TcOCl; yields oxotechnetium(V) complexes containing the oxidized form 2-(2-hydroxyphenyl)benzothiazole (Duatti et al., 1988). In the present paper we describe the synthesis of oxotechnetium(V) complexes with H2L = tridentate ONS and ON0 Schiff-bases and R-SH = monodentate thioles R-SH and their characterization by elemental analysis and spectroscopic methods.
Experimental Methods The content of Tc was determined by liquid-scintillation counting. i.r. Spectra were recorded in KBr discs on a UR 20 spectrometer and u.v.-vis spectra on a Specord M 40 of Carl-Zeiss Jena; ‘H-NMR spectra were measured on a spectrometer WH 90 DS Bruker Spectrospin; U.V. and NMR spectra were measured in chloroform. Preparations Tetrachlorooxotechnetate(V) was prepared according to Davison et al. (1982). Tc(V) gluconate was prepared by stepwise addition of stannous chloride solution to an aqueous solution of pertechnetate in an excess of sodium gluconate, by Johannsen and Spies (1981). The ligands H,L, H,salabt (Cloasz, 1916), H,-acacabt and H,salap (Alyea and Malek, 1975) were prepared by known published methods. 185
H.-J.
186
P~ETZSCH er al.
+?‘=cH9 (ring
XH
bn
a)
(rmg
X=0
HI ralap
x=s
H~salabt
-CH
OH
Fig. I. Schiff-base ligands. procedure
.for the preparation
of
cr>,stalline
complexes Method (a). A solution of IOO~~rnol of the appropriate Schiff-base and 100 pmol of the thiole in 2 mL ethanol is added, dropwise, to a stirred solution of 100 pmol Bu,N[TcOCl,] in 2 mL chloroform. The colour of the reaction mixture turns to red-brown. After stirring for 30 min and reducing the volume to 2 mL brown solids precipitate. The solids are separated and dissolved in 2 mL chloroform. The solution is filtered and 3 mL methanol are added. After standing in a refrigerator overnight red-brown crystals precipitate. Yields are in the range of 4&70%. Method (3). A solution of 50bmol of the Schiffbase and 50 pmol of the appropriate thiole in 0.5 mL acetone is added, dropwise, to a stirred aqueousacetonic solution (2 : 1, v/v) of 50 pmol Tc gluconate. The reaction mixture becomes red-brown and brown solids precipitate. The solids are separated, washed twice with water and dissolved in 2 mL chloroform as described above. Yields are in the range of 4@55%.
Results and Discussion The ligands H,L (Fig. 1) and R-SH yield a full range of complexes TcOL(SR) (Table I). The complexes were synthesized by two routes (Fig. 2): (a) by
Table
I. Tc complexes
+
with tridentate
-+
TiOL(SR)
scheme
for the
preparation
I
Z 3 4 5 6 I
Schiff-base salabt salabc salabt salabt acacabt acacabt Ydlkip
*L&and exchange reaction netium gluconate
reaction of tetrachlorooxotechnetate(V) in ethanolic solution: and (b) by reaction of Tc(V) gluconate in aqueous solution with a stoichiometric amount of a I: 1 mixture of the SchifTbase!thiole ligands. Both precursors proved to be useful starting materials for the preparation of oxotechnetium(V) complexes. preferably with sulphur donor ligands (Davison et al.. 1980; Spies and Johannsen. 1981). because of their ease of preparation and their reactivity. Compound 7 was not obtained starting from Tc gluconate since the more reactive tetrachlorooxotechnetate(V) is required for its preparation. It should be emphasized, however, that combined action of both ligdnds is required to achieve good results. After the reaction of tetrachlorooxotechnetate(V) with Schiff-base ligand alone and subsequent addition of the monothiole co-ligand, only small amounts of the expected compounds are obtained. In this connection it should be mentioned that TcOLCl does not itself react with thiole group containing bidentate ligands (Tisato et al., 1987). After separate addition of the ligand, Tc gluconate yields complexes derived from the individual ligand species. These seem to bis(Schiffbase)oxotechnetium complexes (Spies et al., 1984) and monothiole containing complexes which differ in their composition from those described for steritally-hindered arenethiolate ligands [TcO(ArS),] by Davison et al. (1986). The complexes are obtained as dark brown crystalline solids, which do not show any signs of decomposition in storage in air at room temperature. The compounds are soluble in chloroform and acetone. slightly soluble in methanol and ethanol and insoluble in water. The analytical and spectroscopic properties (Tables 2 and 3) are consistent with the formulation
ONS- and ONO-donor
R-SH C,H,-Sh p-CH1OOC-C,H,-SH n-C,H,,-SH C:H,OOC-CH,-SH p-Ch,OOC-C6H,-SH n-C,H,-SH p-CH,OOC-C,H,-SH starting
of complexes
yields).
Schlff-bases
and monothmles Yield (%)*
Compound
zn:L:i?,
,//*,“’
RSH*
2. Reaction
/
RSH
TcOL (SR) (‘poor
H,acacabt
General
/
ll,L
H,L !48
Fig.
EC-CH,
sn
/
,\\\__\\j TCOLCL
b)
TcOgluc
TCOC1;
m.p. (9CC)
(a)
(b)
217-21X 241-242 R&85 163-164 209-2 IO 95%97 735 237
70 5s
55 50 40 50
(a) from tetrachlorooxotechnetate(V)
60 40 40 and (b) from tech-
Lipophilic Tc complexes-VII Table 2. Analvtical Analytical Compound 1 2 3 4 5 6 7
187
data of comolexes data, found/calculated
(%)
C
H
N
s
TC
50.1/50.6 49.0149.4 52.2/51.7 44.3144.3 46.9146.8 43.7/44.0 49.5/51.1
3.1/3.1 3.2/3.3 5.5j5.3 3.513.5 3.613.7 4.8/4.9 3.6/3.3
2.913.1 2.312.7 2.812.6 3.213.0 2.612.9 3.4i3.4 2.5/2.8
14.5114.2 12.5112.6 13.2/13.1 13.7/13.6 13.4/13.2 14.1/15.6 6.516.5
22.1122.0 19.5119.4 23.3120.3 21.8/21.5 21.5/20.3 23.8/24.2 20.9/20. I
Table 3. u.v.~vis and 1.r. spectra i.r. (cm-‘) Comoound
u.v.-vis 271(4.36), 271(4.36), 274(4.28), 275(4.49).
1
2 3 4 5 6 I (a)’ (b)’
338(4.18). 338(4.08). 334(4. I2), 334(4.30) 392(4. IO) 389(3.70) 390(3.90), 335(4.04), 333(4.08),
320(4.20), 271(4.18).
*Values of (a) TcO(salabt)Cl tThree shoulders.
(nm) (loe c)
l-c=0
413(3.96) 408(3.84) 408(3.84) 401(4.05)
475(3.70)t 406sh((3.60) 445sh(3.60)
and (b) TcO(salap)Cl
Table 4. ‘H-NMR
(Bandoli
Compound
(CDCI,)
ring c* OCH,
4.58 t 4.74 4.20 1.24
AB q t
2H 2H 3H
SCH, O%-CH, OCH,-CA
7.72 i 8.05
AA’BB’
4H
ring c
3.94
s
3H
OCH,
8.09 + 7.72
AA’BB’
4H
ring c
3.95
s
3H
OCH,
8H IH
ring a,b H-C=N
7.82+8.12 3.97
4
7.lL8.0 9.48
m s
8H IH
ring a,b H--C=N
5
7.s7.6
m
4H
7
(ppm)
4H 3H
m s
s
1H
H-C=C
s s
3H 3H
CH, CH,
7.G7.7 9.18
m s
8H IH
H-C=N
ring a,b
1725
Signals of thiole part
7.1-7.x 9.50
5.87
1725 1720
AA’BB s
2
2.60 2.20
1725
er al., 1984) in ethanol.
part
ring a
c--o
1610 I620 1610 1620 159s 1580 1610
data of Tc comolexes
’ H-NMR Signals of Schiff-base
C=N
950 940 980 965 950 960 965 970 980
*Ring a,b see Fig. I, ring c = (subst.) phenyl (see Table I).
TcOL(SR). This formulation as oxotechnetium complexes is confirmed by the presence of intense bands in the i.r. spectra assigned to Td vibration. Compared to the chlorine coordinated compounds TcO(salabt)Cl (Tc==-O 970 cm- ‘) and TcO(salap)Cl (Tc===O 980 cm-‘) (Bandoli et al., 1984), the bands of the thiole coordinate compounds described here are in the region of 94G980 cm-‘. [Six-coordinate complexes (Tisato et al., 1987) are ca. 40 cm-’ lower than those of TcO(salabt)Cl and TcO(salap)Cl]. C==N bands are found in the range of 1580-1620 cm-‘. The assignment is complicated by interference with bands of the aromatic rings (Table 3). The ‘H-NMR data of compounds 2, 4, 5 and 7 (Table 4) clearly indicate the presence of both the Schiff-base and monothiole ligand in a ratio of 1: 1 in the complex. The azomethine protons of the Schiffbase ligands (Alyea and Malek, 1975) are shifted downfield upon complexation by more than 1 ppm. The U.V. spectra are listed in Table 3. In general the spectra of the Schiff-baseithiole coordinated compounds are similar to the corresponding Schiff-
base/chloride coordinated compounds. As already observed for TcO(salabt)Cl and TcO(salap)Cl (Bandoli et al., 1984), the bands for the salabt complexes with SNO donaton (l-4) (which appear at 401413 nm) are shifted to 475 for the salap compound (7) with ON0 donors. In addition to the bands listed in Table 3, spectra of the Tc-salabt complexes (I-4) show a shoulder at about 500 nm. The influence of R on the spectra is practically negligible. Our findings suggest a configuration of compounds l-7 corresponding to that of TcO(salabt)Cl and TcO(salap)Cl (Bandoli et al., 1984). Due to the different arrangement of the tridentate ligand, two enantiomers should exist (Fig. 3).
Fig. 3. Configuration
of complexes
TcOL(SR)
( x S.0).
H.-J. PIETZSCH et nl.
188
The facility of formation of Tc complexes containing tridentate Schiff-bases and monodentate thiole ligands is remarkable insofar as “mixed” compounds MOL’ L, where L’ = tridentate Schiff-bases and L = quinoline-Gthiole and N-b-nitrobenzylidene)-2amino thiophenole, were obtained only for M = Re but not for Tc (Tisato et al., 1987). In sum, the synthesis of neutral complexes TcOL(SR) confirms the validity of the 3 + I concept as formulated by Pietzsch et al., (1989a,b) as a tool for the design of small-sized, neutral Tc complexes.
References Alyea E. C. and Malek A. (1975) Can. J. Chem Bandoli G., Mazzi U.. Wilcox B. E.. Jurisson Deutsch E. (1984) Inorg. C/tint. Acta 95, 217. Claasz M. (1916) Chem Brr. 49, 1141.
53, 939. S. and
Davison A., Orvig C., Trop H. S.. Sohn M.. DePamphilis B. V. and Jones A. G. (1980) Inorg. Chem. 19. 1988. Davison A., Trap H. S., DePamphilisB. V. and Jones A. G. (1982) Inorg. Synfh. 21, 160. Davison A., de Vries N., Dewan J. and Jones A. G. (1986) Inorg. Chim. Acta 120, Ll5. Duatti A.. Marchi A.. Rossi R., Magon L., Deutsch E.. Bertolasi V. and Bellucci F. (1988) Inorg. Chem. 27,4208. Johannsen B. and Spies H. (1981) Chemie und Radiopharmakologie uon Technetiumkomple.ren. CNR, Rossendorf. Pietzsch H.-J.. Spies H., Hoffmann S. and Stach A. (1989a) Inorg. Chim. Acfa. Submitted for publication. Pietzsch H.-J.. Spies H. and Hoffman S. (1989b) Inorg, Chim. Acra Submitted for publication. Spies H. and Johannsen B. (1981) Inorg. Chim. Acra 48, 255. Spies H. and Pietzsch H.-J. (1988) Annual Report CNR Rossendorf. Spies H., Pietzsch H.-J. and Abram U. (1984) J. Radroanal. Nucl. Chem. Letr. 85, 339. Ttsato F., Refosco F.. Mazzi U., Bandoli G. and Nicolim M. (1987) J. Chrm. Sot. Dalton Trans. 1693.
1990 Copyright
0883-2889/90 $3.00 + 0.00 cs 1990 Pergamon Press plc
Lipophilic Technetium Complexes-VII. Neutral Oxotechnetium(V) Complexes of Tridentate Schiff-bases Containing Monothioles as Co-ligands H.-J. PIETZSCH,’ ‘Central
Institute
H. SPIES,‘*
S. HOFFMANN’
and
D. SCHELLER’
of Nuclear Research, Rossendorf 8051 Dresden, Postfach 19 and ‘Dresden University of Technology, Dresden, G.D.R.
(Received
20 February
1989; in revised form 26 April 1989)
Five-coordinate oxotechnetium(V) complexes TcOL(SR), where H,L = Schiff-bases N-salicylidene-2aminothiophenole (H,salabt), N-acetylacetone-2-aminothiophenole (H,acacabt) or N-salicylidene-2aminophenole (H,sap) and R-SH = thiophenoles, mercaptanes or 2-mercaptoacetic acid ethylester, are prepared by the reaction of tetrachlorooxotechnetate(V) or Tc(V) gluconate with a I:1 mixture of the appropriate tridentate/monodentate ligands. The products are characterized by elemental analysis, u.v.-vis, i.r. and ‘H-NMR spectroscopy. The compounds represent the first Schiff-base complexes of Tc(V) which contain monodentate thioles as co-ligands.
Introduction Recently we were able to achieve synthesis of neutral, small-sized Tc complexes TcO(SXS)(SR) by joint action of dianionic tridentate ligands HSXSH and monodentate thiole ligands R-SH on appropriate oxotechnetium(V) precursors (Pietzsch et al., 1989a,b) and suggest that this method could be a general approach to new neutral Tc complexes (Spies and Pietzsch, 1988). The continuing interest in the design of neutral Tc complexes and our own desire to exploit the full chemistry range of the Tc compounds based on 3 + 1 donor ligand combinations encouraged us to involve tridentate Schiff-bases, in combination with monothioles, to synthesize neutral oxotechnetium(V) complexes. As reported earlier by Bandoli et al. (1984) and Tisato et al. (1987), tridentate Schiff-bases provide a variety of Tc=O complexes including those with additional, preferably bidentate, co-ligands. Thus, the reaction of the tridentate Schiff-bases N-salicylidene-2-aminothioor N-salicylidene-2-aminophenole (Hz salabt) phenole (H,sap) with TcOCl; gives TcOLCl. Mixed complexes of the formulation TcOLL*, where L2 = bidentate Schiff-base anions or quinolin-8-01, were obtained by the subsequent reaction of TcOLCl with those bidentate ligands. Reaction of 2-(2-
*Author for correspondence
hydroxyphenyl)benzothiazohne with TcOCl; yields oxotechnetium(V) complexes containing the oxidized form 2-(2-hydroxyphenyl)benzothiazole (Duatti et al., 1988). In the present paper we describe the synthesis of oxotechnetium(V) complexes with H2L = tridentate ONS and ON0 Schiff-bases and R-SH = monodentate thioles R-SH and their characterization by elemental analysis and spectroscopic methods.
Experimental Methods The content of Tc was determined by liquid-scintillation counting. i.r. Spectra were recorded in KBr discs on a UR 20 spectrometer and u.v.-vis spectra on a Specord M 40 of Carl-Zeiss Jena; ‘H-NMR spectra were measured on a spectrometer WH 90 DS Bruker Spectrospin; U.V. and NMR spectra were measured in chloroform. Preparations Tetrachlorooxotechnetate(V) was prepared according to Davison et al. (1982). Tc(V) gluconate was prepared by stepwise addition of stannous chloride solution to an aqueous solution of pertechnetate in an excess of sodium gluconate, by Johannsen and Spies (1981). The ligands H,L, H,salabt (Cloasz, 1916), H,-acacabt and H,salap (Alyea and Malek, 1975) were prepared by known published methods. 185
H.-J.
186
P~ETZSCH er al.
+?‘=cH9 (ring
XH
bn
a)
(rmg
X=0
HI ralap
x=s
H~salabt
-CH
OH
Fig. I. Schiff-base ligands. procedure
.for the preparation
of
cr>,stalline
complexes Method (a). A solution of IOO~~rnol of the appropriate Schiff-base and 100 pmol of the thiole in 2 mL ethanol is added, dropwise, to a stirred solution of 100 pmol Bu,N[TcOCl,] in 2 mL chloroform. The colour of the reaction mixture turns to red-brown. After stirring for 30 min and reducing the volume to 2 mL brown solids precipitate. The solids are separated and dissolved in 2 mL chloroform. The solution is filtered and 3 mL methanol are added. After standing in a refrigerator overnight red-brown crystals precipitate. Yields are in the range of 4&70%. Method (3). A solution of 50bmol of the Schiffbase and 50 pmol of the appropriate thiole in 0.5 mL acetone is added, dropwise, to a stirred aqueousacetonic solution (2 : 1, v/v) of 50 pmol Tc gluconate. The reaction mixture becomes red-brown and brown solids precipitate. The solids are separated, washed twice with water and dissolved in 2 mL chloroform as described above. Yields are in the range of 4@55%.
Results and Discussion The ligands H,L (Fig. 1) and R-SH yield a full range of complexes TcOL(SR) (Table I). The complexes were synthesized by two routes (Fig. 2): (a) by
Table
I. Tc complexes
+
with tridentate
-+
TiOL(SR)
scheme
for the
preparation
I
Z 3 4 5 6 I
Schiff-base salabt salabc salabt salabt acacabt acacabt Ydlkip
*L&and exchange reaction netium gluconate
reaction of tetrachlorooxotechnetate(V) in ethanolic solution: and (b) by reaction of Tc(V) gluconate in aqueous solution with a stoichiometric amount of a I: 1 mixture of the SchifTbase!thiole ligands. Both precursors proved to be useful starting materials for the preparation of oxotechnetium(V) complexes. preferably with sulphur donor ligands (Davison et al.. 1980; Spies and Johannsen. 1981). because of their ease of preparation and their reactivity. Compound 7 was not obtained starting from Tc gluconate since the more reactive tetrachlorooxotechnetate(V) is required for its preparation. It should be emphasized, however, that combined action of both ligdnds is required to achieve good results. After the reaction of tetrachlorooxotechnetate(V) with Schiff-base ligand alone and subsequent addition of the monothiole co-ligand, only small amounts of the expected compounds are obtained. In this connection it should be mentioned that TcOLCl does not itself react with thiole group containing bidentate ligands (Tisato et al., 1987). After separate addition of the ligand, Tc gluconate yields complexes derived from the individual ligand species. These seem to bis(Schiffbase)oxotechnetium complexes (Spies et al., 1984) and monothiole containing complexes which differ in their composition from those described for steritally-hindered arenethiolate ligands [TcO(ArS),] by Davison et al. (1986). The complexes are obtained as dark brown crystalline solids, which do not show any signs of decomposition in storage in air at room temperature. The compounds are soluble in chloroform and acetone. slightly soluble in methanol and ethanol and insoluble in water. The analytical and spectroscopic properties (Tables 2 and 3) are consistent with the formulation
ONS- and ONO-donor
R-SH C,H,-Sh p-CH1OOC-C,H,-SH n-C,H,,-SH C:H,OOC-CH,-SH p-Ch,OOC-C6H,-SH n-C,H,-SH p-CH,OOC-C,H,-SH starting
of complexes
yields).
Schlff-bases
and monothmles Yield (%)*
Compound
zn:L:i?,
,//*,“’
RSH*
2. Reaction
/
RSH
TcOL (SR) (‘poor
H,acacabt
General
/
ll,L
H,L !48
Fig.
EC-CH,
sn
/
,\\\__\\j TCOLCL
b)
TcOgluc
TCOC1;
m.p. (9CC)
(a)
(b)
217-21X 241-242 R&85 163-164 209-2 IO 95%97 735 237
70 5s
55 50 40 50
(a) from tetrachlorooxotechnetate(V)
60 40 40 and (b) from tech-
Lipophilic Tc complexes-VII Table 2. Analvtical Analytical Compound 1 2 3 4 5 6 7
187
data of comolexes data, found/calculated
(%)
C
H
N
s
TC
50.1/50.6 49.0149.4 52.2/51.7 44.3144.3 46.9146.8 43.7/44.0 49.5/51.1
3.1/3.1 3.2/3.3 5.5j5.3 3.513.5 3.613.7 4.8/4.9 3.6/3.3
2.913.1 2.312.7 2.812.6 3.213.0 2.612.9 3.4i3.4 2.5/2.8
14.5114.2 12.5112.6 13.2/13.1 13.7/13.6 13.4/13.2 14.1/15.6 6.516.5
22.1122.0 19.5119.4 23.3120.3 21.8/21.5 21.5/20.3 23.8/24.2 20.9/20. I
Table 3. u.v.~vis and 1.r. spectra i.r. (cm-‘) Comoound
u.v.-vis 271(4.36), 271(4.36), 274(4.28), 275(4.49).
1
2 3 4 5 6 I (a)’ (b)’
338(4.18). 338(4.08). 334(4. I2), 334(4.30) 392(4. IO) 389(3.70) 390(3.90), 335(4.04), 333(4.08),
320(4.20), 271(4.18).
*Values of (a) TcO(salabt)Cl tThree shoulders.
(nm) (loe c)
l-c=0
413(3.96) 408(3.84) 408(3.84) 401(4.05)
475(3.70)t 406sh((3.60) 445sh(3.60)
and (b) TcO(salap)Cl
Table 4. ‘H-NMR
(Bandoli
Compound
(CDCI,)
ring c* OCH,
4.58 t 4.74 4.20 1.24
AB q t
2H 2H 3H
SCH, O%-CH, OCH,-CA
7.72 i 8.05
AA’BB’
4H
ring c
3.94
s
3H
OCH,
8.09 + 7.72
AA’BB’
4H
ring c
3.95
s
3H
OCH,
8H IH
ring a,b H-C=N
7.82+8.12 3.97
4
7.lL8.0 9.48
m s
8H IH
ring a,b H--C=N
5
7.s7.6
m
4H
7
(ppm)
4H 3H
m s
s
1H
H-C=C
s s
3H 3H
CH, CH,
7.G7.7 9.18
m s
8H IH
H-C=N
ring a,b
1725
Signals of thiole part
7.1-7.x 9.50
5.87
1725 1720
AA’BB s
2
2.60 2.20
1725
er al., 1984) in ethanol.
part
ring a
c--o
1610 I620 1610 1620 159s 1580 1610
data of Tc comolexes
’ H-NMR Signals of Schiff-base
C=N
950 940 980 965 950 960 965 970 980
*Ring a,b see Fig. I, ring c = (subst.) phenyl (see Table I).
TcOL(SR). This formulation as oxotechnetium complexes is confirmed by the presence of intense bands in the i.r. spectra assigned to Td vibration. Compared to the chlorine coordinated compounds TcO(salabt)Cl (Tc==-O 970 cm- ‘) and TcO(salap)Cl (Tc===O 980 cm-‘) (Bandoli et al., 1984), the bands of the thiole coordinate compounds described here are in the region of 94G980 cm-‘. [Six-coordinate complexes (Tisato et al., 1987) are ca. 40 cm-’ lower than those of TcO(salabt)Cl and TcO(salap)Cl]. C==N bands are found in the range of 1580-1620 cm-‘. The assignment is complicated by interference with bands of the aromatic rings (Table 3). The ‘H-NMR data of compounds 2, 4, 5 and 7 (Table 4) clearly indicate the presence of both the Schiff-base and monothiole ligand in a ratio of 1: 1 in the complex. The azomethine protons of the Schiffbase ligands (Alyea and Malek, 1975) are shifted downfield upon complexation by more than 1 ppm. The U.V. spectra are listed in Table 3. In general the spectra of the Schiff-baseithiole coordinated compounds are similar to the corresponding Schiff-
base/chloride coordinated compounds. As already observed for TcO(salabt)Cl and TcO(salap)Cl (Bandoli et al., 1984), the bands for the salabt complexes with SNO donaton (l-4) (which appear at 401413 nm) are shifted to 475 for the salap compound (7) with ON0 donors. In addition to the bands listed in Table 3, spectra of the Tc-salabt complexes (I-4) show a shoulder at about 500 nm. The influence of R on the spectra is practically negligible. Our findings suggest a configuration of compounds l-7 corresponding to that of TcO(salabt)Cl and TcO(salap)Cl (Bandoli et al., 1984). Due to the different arrangement of the tridentate ligand, two enantiomers should exist (Fig. 3).
Fig. 3. Configuration
of complexes
TcOL(SR)
( x S.0).
H.-J. PIETZSCH et nl.
188
The facility of formation of Tc complexes containing tridentate Schiff-bases and monodentate thiole ligands is remarkable insofar as “mixed” compounds MOL’ L, where L’ = tridentate Schiff-bases and L = quinoline-Gthiole and N-b-nitrobenzylidene)-2amino thiophenole, were obtained only for M = Re but not for Tc (Tisato et al., 1987). In sum, the synthesis of neutral complexes TcOL(SR) confirms the validity of the 3 + I concept as formulated by Pietzsch et al., (1989a,b) as a tool for the design of small-sized, neutral Tc complexes.
References Alyea E. C. and Malek A. (1975) Can. J. Chem Bandoli G., Mazzi U.. Wilcox B. E.. Jurisson Deutsch E. (1984) Inorg. C/tint. Acta 95, 217. Claasz M. (1916) Chem Brr. 49, 1141.
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Davison A., Orvig C., Trop H. S.. Sohn M.. DePamphilis B. V. and Jones A. G. (1980) Inorg. Chem. 19. 1988. Davison A., Trap H. S., DePamphilisB. V. and Jones A. G. (1982) Inorg. Synfh. 21, 160. Davison A., de Vries N., Dewan J. and Jones A. G. (1986) Inorg. Chim. Acta 120, Ll5. Duatti A.. Marchi A.. Rossi R., Magon L., Deutsch E.. Bertolasi V. and Bellucci F. (1988) Inorg. Chem. 27,4208. Johannsen B. and Spies H. (1981) Chemie und Radiopharmakologie uon Technetiumkomple.ren. CNR, Rossendorf. Pietzsch H.-J.. Spies H., Hoffmann S. and Stach A. (1989a) Inorg. Chim. Acfa. Submitted for publication. Pietzsch H.-J.. Spies H. and Hoffman S. (1989b) Inorg, Chim. Acra Submitted for publication. Spies H. and Johannsen B. (1981) Inorg. Chim. Acra 48, 255. Spies H. and Pietzsch H.-J. (1988) Annual Report CNR Rossendorf. Spies H., Pietzsch H.-J. and Abram U. (1984) J. Radroanal. Nucl. Chem. Letr. 85, 339. Ttsato F., Refosco F.. Mazzi U., Bandoli G. and Nicolim M. (1987) J. Chrm. Sot. Dalton Trans. 1693.