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A comparative 13C and 19F NMR study of some nickel, zinc and cobalt monothio-β-diketonate complexes
J. inorg, nucL Chem. VoL 43, pp, 1807-1810, 1981 Printed in Great Britain.
0022-1902/81/0818074)4502.00/0 Pergamon Press Ltd.
A COMPARATIVE 13C AND 19F NMR STUDY OF SOME NICKEL, ZINC AND COBALT MONOTHIO-fl-DIKETONATE COMPLEXES DANIEL T. HAWORTH* and DIANA L. MAAS Department of Chemistry,Marquette University, Milwaukee,WI 53233, U.S.A. and MANORANJAN DAS School of Chemistry,Universityof New South Wales, Kensington,N.S.W. 2033, Australia
(Received 29 September 1980; received [or publication 17 October 1980) Abstract--The t3C and 19F NMR spectra of the nickel, zinc and cobalt complexesof l,l-difluoro-4-mercapto-4-(2'thienyl)but-3-en-2-one, 1,1,l-trifluoro-4-mercapto-4-(2'-thienyl)but-3-en-2-one and 1,1,l-trifluoro-4-mercapto-4-(2'naphthyl)but-e-en-2-oneare reported. The nickel and zinc complexes have a cis-square planar, and tetrahedral geometry, respectively. Our NMR data support a facial (cis) octahedral geometry for the cobalt complexes.The high and low frequency IR spectra of the zinc complexesshow a smallvariationin the diketone ring vibrationswith thienyl or naphthyl substituents.The 19F NMR spectra show the chemical shift of the trifluoromethylgroup to be metal dependent. INTRODUCTION The substitution of one of the oxygen atoms with a sulfur atom in/3-diketones has been shown to yield metal monothio-/~-diketonate complexes which are monomeric, anhydrous and soluble in organic solvents, whereas metal complexes of/3-diketones are solvated, polymeric and insoluble in organic solvents[l]. Recently we have reported on the 13C and t9F NMR spectra of various trifluoromonothio-/3-diketonate complexes of the ligand RC(SH) = CHCOCF3. The data show that the chemical shift of the carbons of the R group (where R is substituted phenyl) is not dependent on the metal or on the geometry of the complex[2]. Instead the data show a dependence of the t3C NMR chemical shift of the diketone carbons with metal complexed. Our tgF NMR data also showed the chemical shift of the trifluoromethyl group to be metal dependent[2]. In continuation of our NMR studies of monothio-fldiketonate complexes we now report on the 13C and tgF NMR spectra of a series of nickel, zinc and cobalt complexes of RC(SH)=CHCOCF3 (R=2'-thienyl and 2'naphthyl) and RC(SH)=CHCOCHF2 (R = 2'-thienyl) and their corresponding ligands.
ligands Sthdf-H, Sthtf-H and Snpff-H are presented in Table 1. For comparative purposes, the ~3C NMR chemical shift of the ligands are also shown. One notes that the thiocarbonyl carbon of Sthdf and Sthff complexes are more shielded than the thiocarbonyl carbon of the respective ligands but it is deshielded in the Snptf complexes. Similarly, a deshielding of the carbonyl carbon in the Sthdf-H and Sthff-H complexes is observed as compared to the Snpth-H complexes where the carbonyl carbon is more shielded. As noted previously, the carbonyl carbon resonance in monothio-fl-diketonate complexes occurs at higher field as compared to metal aceIyacetonate(acac) complexes [6]. On the other hand, the methine carbons are more deshielded regardless of the ligand. The chemical shift difference between the ligands and their corresponding complexes carbons are thiocarbonyl > carbonyl > methine. In this study and in our previous report the thiocarbonyl resonance generally occurs at a lower field compared to the carbonyl carbon[2]; however, the nickel complex, Ni(Sthdfh, gave a thiocarbonyl resonance at a higher field (174.7 Hz) than its carbonyl carbon (177.5 Hz).
EXPERIMENTAL The various monothio-/3-diketonatezinc, nickel and cobalt complexes were prepared as previously described[3-5].The t3C and 19F NMR were recorded in CDC13 and were taken with a JEOL-FX60 NMR Spectrometer.The t3C NMR spectra were run over a 4000Hz sweep width using 8 or 16K data points with tetramethylsilane (TMS) as an internal standard. The 19F NMR spectra were run over a 15,150Hz sweep width using CFCI3as an internal standard. IR spectra were taken on a Beckman IR-4620 recording spectrophotomer using the KBr pellet and Nujolpolyethylenesheet techniques. RESULTS AND DISCUSSION
The 13C NMR chemical shift data (ppm) for the nickel, zinc and cobalt complexes of the monothio-/3-diketonate *Author to whom correspondenceshould be addressed.
R
H I
__C_
R"
"C~'z~'~ / I [[ S--.H--'O
R 2'-thienyl 2'-thienyl 2'-naphthyl
R'
Ligand
CHF2 Sthdf-H CF3 Sthff-H CF3 Snptf-H
The CF3 group has a larger shielding effect on the carbonyl and methine carbon resonances than the CHF2 group in thdf and thff complexes. This shielding has also been observed for the methine carbon in acetylacetonate ligands containing CF3 groups substituted for CH3 groups. This shift has been explained by an electric field effect[7]; however, a more recent study indicates that the paramagnetic effect in NMR chemical shift theory is dominant and the compounds are quasi-aromatic [8]. One
1807
D. T. HAWORTHand D. L. MAAS
1808
Table 1. ~3C NMR chemical shifts (ppm) and coupling constants (Hz) of some monothio-~-diketonatecomplexes of nickel, zinc and cobalt
C-SS
Compound
C-O
C-_._HH
2_
Th4 en),l Carbons
3_
4_
5_
168.8 (23.9)
104.7 (4.9)
151.1
135.8
128.4
128.8
II0.0 (245.1)
NJ(Sthdf) 2 174.7
177.5 (24.4)
107.9 (2.0)
143.5
132.2
128.5
128.5
109.7 (250.0)
Zn(Sthdf)2 184.7
183.7 (22.9)
106.9 (2.4)
150.0
133.9
128.5
129.6
110.8 (251.2)
Co(Sthdf) 3 181.0
177.4 (26.9)
104.8 (2.4)
143.1
131.7
128.8
128.2
109,8 (252.4)
Sthtf-H
196.4
164.5 (35,1)
104.5 (2.9)
149.0
135.8
128.8
128.9
118.3 (279.3)
Nf(Sthtf) 2 176.4
169.1 (34.2)
107.5 (1.5)
143.3
133,3
128.8
128,9
116,6 (284.2)
Zn(Sthtf) 2 187.9
175.1 (33.1)
105.7 (2.0)
149.5
135,1
128.9
130,1
117,9 (285.7)
Co($thtf)3
173.9 (34.2)
104.6 (2.0)
143.0
132.6
128.5
129.2
116.3
Napllthyl Carbons ~ 9
1._00
Sthdf-H
200=7
179.4
2_
°..
(285.7)
182.4
177.1 (35.2)
108.9 (2.0)
134.7
123.2
132.6
138.3
117.1 (287.1)
Nt(_$optf12b 187.5
170.6 (34.7)
110.5 (2.0)
134.4
123.2
132.4
137.1
116.7 (283.7)
ZoC$nptb)2c 200.3
176.6 (33.7)
109.9 (1.9)
134.6
123.8
132.2
142.3
117.8 (288.9)
CO(_Snptf)3d 190.7
174.6 (35.2)
167.6 (1.5)
134.4
123.5
132.3
137.2
116.3 (286.2)
Snptf-~
Other naphthylcarbon resonances a t : (a)
12Q.9,
128.7, 128.0, 127.~, 127.1, 127.0
4
3
8
9
I
-
DK
(b) 128.9, 128.4, 127.8, 127.5, 126.9 (2x) (¢)
129.2, 126.2, 128.0, 127.5, 127.3, 125.8
5
4
(d) 128.8, 128.2, 127.7, 127.4, 127.1,126.8
also notes that the chemical shift of the CF3 and CO carbons are very similar for each respective metal in the Sthtf and Snptf complexes. The 19F NMR spectra of other monothio-fl-diketonate complexes showed the chemical shift of the CFa group to be metal dependent[2]. The 13C-19Fcoupling constants are larger in the Sthdf and Sthtf complexes than in the Snptf complexes as compared to the ligands. The trifiuoromethyl carbon of the 2'-naphthyl substituent gave the largest coupling constant (287.1 Hz). Spin coupling J('3C-I'F) was observed for the fluoro, methine and carbonyl carbons with the CHF2 and CF3 substituents giving triplet and quartet resonances, respectively. The thienyl carbon assignments in Table 1 are in accord with our previous study[9]. The quaternary thienyl carbon (C-2) is the most deshielded and has the smallest resonance intensity. This carbon as expected has the largest chemical shift difference in the complexes as compared to the ligand. There is a significant change in this shift in the nickel and cobalt complexes as compared to the zinc complexes. It is too early to speculate on whether this is a result of geometry and/or metal complexed. The chemical shift of some 2'-naphthyl carbons (Table 1) are tentatively assigned for C-2, C-3 and C-9 and C-10. These assignments are based on the carbon resonances in 2-naphthylaldehyde[10]. C-2, C-9 and C10 carbons are quaternary of low intensity and the most
deshielded. The ten carbons of the naphthyl group for each complex and the ligand each show a different chemical shift except the 126.9ppm resonance of the nickel complex which gave twice the intensity of the other peaks. The C-3 resonance (ortho) occurs at high field. All the cobalt complexes (COL3) have a cis(fac) configuration. Since the ligand is in unsymmetrical, only one resonance is expected for a cis configuration for each type of carbon. A trans(mer) configuration having nonequivalent carbon sites would give a spectrum having
(s
/s
o o
trans(mer)
cis(fac)
three resonances for each carbon. The larger dipole moments of Co(Sthtf)3 (7.14D)[5] and Co(Snpff)3 (6.90D) [11] also support a cis(fac) structure. While it was not possible from dipole moment studies to distinguish between facial or meridional-octahedral configurations for Co(Sthdf)~ (4.95D), this 13C NMR study confirms its facial (cis) octahedral structure in CDC1314]. The large dipole moment of the NiL2 complexes sug-
A comparative13Cand 19FNMR study of some nickel, zinc and cobalt monothio-@-diketonatecomplexes
1809
Table 2. 19FNMRchemicalshift data for metal complexesof RC(SH)=CHCOCFS(LHY Complex NIL2
ZnL2
CoL3
R
74 .Fd
3:5t(CH30)2C6H3
2!c4ti3s”
74.5
2!cl
74.7
OHJ~
4!C2HgC6H4
J6.ld
4LC2H60C6H4
J6.od
3:4:5'(CH30)3CgH2
76.ld
2k4H3sb
76.1
2k,0ttJC
76.0
4+i5Oc6H4
J5.ld
3:4:61(Cti30)3C6H2
J6.2d
zk4H3sb
75.1
2!cl
75.1
OHJ~
Geometry
GF3
e&-square
planar
tetrahedral
fat-octahedral
'ppm upfield from WC13 bC4H3S-thierlyl 'CIOHJ-naphthyl ddata taken from ref. 2
gests a c&square planar configuration whereas a transsquare planar configuration would have a smaller dipole moment [4,5]. The still smaller dipole moment values for tetrahedral the ZnLl support a complexes geometry[4,12]. It is apparent that square planar and octahedral complexes of these ligands give a cis arrangement as the most stable configuration in the solid state and in solution. All of the zinc complexes gave IR bands (cm-‘) at cu. 1550 (C-O stretch 1500 (C-C stretch), 1400 (C-H bending), 1250(C-S stretch), 1130 (C-F stretch), 805 (C-H out of plane plus C-S stretch), 430 (Zn-0 stretch), 360 (Zn-S stretch)[lf, 141. The CF, substituents and the thiocarbonyl of the diketonate ligand have been shown to lower the ring frequencies which has also been used to support the quasi-aromatic character of these chelates [8, IS]. The 19F NMR spectra1 data complexes of the ligand RC(SH)=CHCOCF, are displayed in Table 2. As previously noted the organic substituent (thienyl and naphthy]) is not an important factor in the chemical shift, rather, the metals complexed give a good correlation with chemical shift data. For comparative purposes previous data are also included for the CF, substituents monothio+-diketonate chelates[2]. The chemical shift data indicates the order of decreasing field strength: NiLz > CoL, > ZnL,. This is the inverse order of 13CNMR chemical shift data for the thiocarbonyl and carbonyl carbons which also agrees with our previous data[2]. The 19F NMR resonance of the Sthtf-H[9] and Snptf-H ligands occurred at - 74.5 and - 77.3 ppm, respectively.
The fluorine resonances of the naphthyl complexes are more deshielded but the fluorine resonances of the thienyl complexes are more shielded with respect to their ligand resonances. The fluorine resonances of the NiL2, Znh and CoLp complexes of the ligand 2’-C4H$(CS)=CHCOCHF2 which were recorded at - 123.3, - 124.5and - 123.1ppm; respectively, were all more deshielded than the fluorine resonance of the protonated ligand (Sthdf-H) at - 125.1ppm. Finally, our previous Y! NMR study of various monothio-/I-diketonate ligands supports the view that the enol form of the ligand dominates in solution[9]. This study included the Sthdf-H and Sthtf-H ligands and now the 13C NMR spectrum of l,l,l-tritIuoro4mercapto-4-(2’naphthyl)but-3-en-2-one (Snptf-H) indicates the enol form as also being the major tautomer in solution. Only one thiocarbonyl and carbonyl carbon resonance and no ring ethylene carbon (CH,) was observed. This study supports the ‘H NMR work which has shown the predominance of the enol tautomer for monothio-fi-diketonate ligands [ 16,171. Acknowledgemenrs-This project was partially supported by the Marauette University Committee on Research and by a NSF Undergraduate Research Fellowship to D. Maas. The assistance of Mr. James W. Beery in taking the lsF NMR spectra is gratefully appreciated.
1. M. Das, therein.
Inorg.
RRFRRRNCRS Chim. Acta 36, 79 (1979) and refs. cited
1810
D.T. HAWORTH and D. L. MAAS
2. M. Das and D. T. Haworth, J. lnorg. Nucl. Chem. in press. 3. S. E. Livingstone and D. S. Moore, Austral. J. Chem. 29, 283 (1976). 4. M. Das, Transition Met. Chem. 5, 17 (1980). 5. M. Das, S. E. Livingstone, S. W. Filipczuk, J. W. Hayes and D. V. Radford, ~ Chem. Soe. Dalton 1409 (1974). 6. C. A. Wilkie and D. T. Haworth, J. Inorg. Nucl. Chem. 40, 195 (1978). 7. J. C. Hammel and J. A. S. Smith, J. Chem. $oe. (A) 1855 (1970). 8. C. L. Watkins and M. E. Harris, J. lnorg. Nucl. Chem. 40, 1765 (1978). 9. D. T. Haworth and M. Das, lnorg. Nucl. Chem. Lett. 16, 529 (1980). 10. 13C NMR spectra, Sadtler Research Laboratories, Philad-
delphia, Pennsylvania (1979). 11. D. S. Moore, B. Sc(Hons) thesis, University of New South Wales (1974). 12. S. W. Filipczuk, J. W. Hayes, D. V. Radford, M. Das and S. E. Livingstone, J. Chem. Soc. Soc. Dalton 886 (1975). 13. G. Dorange and J. E. Guerchais, Bull. Soc. Chim. 43 (1971). 14. K. C. Joshi and V. N. Pathak, J. lnorg. Nucl. Chem. 38, 3161 (1973). 15. R. C. Mehrotra, R. Bohra and D. P. Gaur, Metal ~Diketonates and Allied Derivatives, p. 239. Academic Press, New York (1978). 16. M. Cox and J. Darken, Coord. Chem. Rev. 7, 29 (1971). 17. R. C. Mehrotra, R. Bohra and D. P. Gaur, Metal flDiletonates and Allied Derivatives, p. 223. Academic Press, New York (1978).
0022-1902/81/0818074)4502.00/0 Pergamon Press Ltd.
A COMPARATIVE 13C AND 19F NMR STUDY OF SOME NICKEL, ZINC AND COBALT MONOTHIO-fl-DIKETONATE COMPLEXES DANIEL T. HAWORTH* and DIANA L. MAAS Department of Chemistry,Marquette University, Milwaukee,WI 53233, U.S.A. and MANORANJAN DAS School of Chemistry,Universityof New South Wales, Kensington,N.S.W. 2033, Australia
(Received 29 September 1980; received [or publication 17 October 1980) Abstract--The t3C and 19F NMR spectra of the nickel, zinc and cobalt complexesof l,l-difluoro-4-mercapto-4-(2'thienyl)but-3-en-2-one, 1,1,l-trifluoro-4-mercapto-4-(2'-thienyl)but-3-en-2-one and 1,1,l-trifluoro-4-mercapto-4-(2'naphthyl)but-e-en-2-oneare reported. The nickel and zinc complexes have a cis-square planar, and tetrahedral geometry, respectively. Our NMR data support a facial (cis) octahedral geometry for the cobalt complexes.The high and low frequency IR spectra of the zinc complexesshow a smallvariationin the diketone ring vibrationswith thienyl or naphthyl substituents.The 19F NMR spectra show the chemical shift of the trifluoromethylgroup to be metal dependent. INTRODUCTION The substitution of one of the oxygen atoms with a sulfur atom in/3-diketones has been shown to yield metal monothio-/~-diketonate complexes which are monomeric, anhydrous and soluble in organic solvents, whereas metal complexes of/3-diketones are solvated, polymeric and insoluble in organic solvents[l]. Recently we have reported on the 13C and t9F NMR spectra of various trifluoromonothio-/3-diketonate complexes of the ligand RC(SH) = CHCOCF3. The data show that the chemical shift of the carbons of the R group (where R is substituted phenyl) is not dependent on the metal or on the geometry of the complex[2]. Instead the data show a dependence of the t3C NMR chemical shift of the diketone carbons with metal complexed. Our tgF NMR data also showed the chemical shift of the trifluoromethyl group to be metal dependent[2]. In continuation of our NMR studies of monothio-fldiketonate complexes we now report on the 13C and tgF NMR spectra of a series of nickel, zinc and cobalt complexes of RC(SH)=CHCOCF3 (R=2'-thienyl and 2'naphthyl) and RC(SH)=CHCOCHF2 (R = 2'-thienyl) and their corresponding ligands.
ligands Sthdf-H, Sthtf-H and Snpff-H are presented in Table 1. For comparative purposes, the ~3C NMR chemical shift of the ligands are also shown. One notes that the thiocarbonyl carbon of Sthdf and Sthff complexes are more shielded than the thiocarbonyl carbon of the respective ligands but it is deshielded in the Snptf complexes. Similarly, a deshielding of the carbonyl carbon in the Sthdf-H and Sthff-H complexes is observed as compared to the Snpth-H complexes where the carbonyl carbon is more shielded. As noted previously, the carbonyl carbon resonance in monothio-fl-diketonate complexes occurs at higher field as compared to metal aceIyacetonate(acac) complexes [6]. On the other hand, the methine carbons are more deshielded regardless of the ligand. The chemical shift difference between the ligands and their corresponding complexes carbons are thiocarbonyl > carbonyl > methine. In this study and in our previous report the thiocarbonyl resonance generally occurs at a lower field compared to the carbonyl carbon[2]; however, the nickel complex, Ni(Sthdfh, gave a thiocarbonyl resonance at a higher field (174.7 Hz) than its carbonyl carbon (177.5 Hz).
EXPERIMENTAL The various monothio-/3-diketonatezinc, nickel and cobalt complexes were prepared as previously described[3-5].The t3C and 19F NMR were recorded in CDC13 and were taken with a JEOL-FX60 NMR Spectrometer.The t3C NMR spectra were run over a 4000Hz sweep width using 8 or 16K data points with tetramethylsilane (TMS) as an internal standard. The 19F NMR spectra were run over a 15,150Hz sweep width using CFCI3as an internal standard. IR spectra were taken on a Beckman IR-4620 recording spectrophotomer using the KBr pellet and Nujolpolyethylenesheet techniques. RESULTS AND DISCUSSION
The 13C NMR chemical shift data (ppm) for the nickel, zinc and cobalt complexes of the monothio-/3-diketonate *Author to whom correspondenceshould be addressed.
R
H I
__C_
R"
"C~'z~'~ / I [[ S--.H--'O
R 2'-thienyl 2'-thienyl 2'-naphthyl
R'
Ligand
CHF2 Sthdf-H CF3 Sthff-H CF3 Snptf-H
The CF3 group has a larger shielding effect on the carbonyl and methine carbon resonances than the CHF2 group in thdf and thff complexes. This shielding has also been observed for the methine carbon in acetylacetonate ligands containing CF3 groups substituted for CH3 groups. This shift has been explained by an electric field effect[7]; however, a more recent study indicates that the paramagnetic effect in NMR chemical shift theory is dominant and the compounds are quasi-aromatic [8]. One
1807
D. T. HAWORTHand D. L. MAAS
1808
Table 1. ~3C NMR chemical shifts (ppm) and coupling constants (Hz) of some monothio-~-diketonatecomplexes of nickel, zinc and cobalt
C-SS
Compound
C-O
C-_._HH
2_
Th4 en),l Carbons
3_
4_
5_
168.8 (23.9)
104.7 (4.9)
151.1
135.8
128.4
128.8
II0.0 (245.1)
NJ(Sthdf) 2 174.7
177.5 (24.4)
107.9 (2.0)
143.5
132.2
128.5
128.5
109.7 (250.0)
Zn(Sthdf)2 184.7
183.7 (22.9)
106.9 (2.4)
150.0
133.9
128.5
129.6
110.8 (251.2)
Co(Sthdf) 3 181.0
177.4 (26.9)
104.8 (2.4)
143.1
131.7
128.8
128.2
109,8 (252.4)
Sthtf-H
196.4
164.5 (35,1)
104.5 (2.9)
149.0
135.8
128.8
128.9
118.3 (279.3)
Nf(Sthtf) 2 176.4
169.1 (34.2)
107.5 (1.5)
143.3
133,3
128.8
128,9
116,6 (284.2)
Zn(Sthtf) 2 187.9
175.1 (33.1)
105.7 (2.0)
149.5
135,1
128.9
130,1
117,9 (285.7)
Co($thtf)3
173.9 (34.2)
104.6 (2.0)
143.0
132.6
128.5
129.2
116.3
Napllthyl Carbons ~ 9
1._00
Sthdf-H
200=7
179.4
2_
°..
(285.7)
182.4
177.1 (35.2)
108.9 (2.0)
134.7
123.2
132.6
138.3
117.1 (287.1)
Nt(_$optf12b 187.5
170.6 (34.7)
110.5 (2.0)
134.4
123.2
132.4
137.1
116.7 (283.7)
ZoC$nptb)2c 200.3
176.6 (33.7)
109.9 (1.9)
134.6
123.8
132.2
142.3
117.8 (288.9)
CO(_Snptf)3d 190.7
174.6 (35.2)
167.6 (1.5)
134.4
123.5
132.3
137.2
116.3 (286.2)
Snptf-~
Other naphthylcarbon resonances a t : (a)
12Q.9,
128.7, 128.0, 127.~, 127.1, 127.0
4
3
8
9
I
-
DK
(b) 128.9, 128.4, 127.8, 127.5, 126.9 (2x) (¢)
129.2, 126.2, 128.0, 127.5, 127.3, 125.8
5
4
(d) 128.8, 128.2, 127.7, 127.4, 127.1,126.8
also notes that the chemical shift of the CF3 and CO carbons are very similar for each respective metal in the Sthtf and Snptf complexes. The 19F NMR spectra of other monothio-fl-diketonate complexes showed the chemical shift of the CFa group to be metal dependent[2]. The 13C-19Fcoupling constants are larger in the Sthdf and Sthtf complexes than in the Snptf complexes as compared to the ligands. The trifiuoromethyl carbon of the 2'-naphthyl substituent gave the largest coupling constant (287.1 Hz). Spin coupling J('3C-I'F) was observed for the fluoro, methine and carbonyl carbons with the CHF2 and CF3 substituents giving triplet and quartet resonances, respectively. The thienyl carbon assignments in Table 1 are in accord with our previous study[9]. The quaternary thienyl carbon (C-2) is the most deshielded and has the smallest resonance intensity. This carbon as expected has the largest chemical shift difference in the complexes as compared to the ligand. There is a significant change in this shift in the nickel and cobalt complexes as compared to the zinc complexes. It is too early to speculate on whether this is a result of geometry and/or metal complexed. The chemical shift of some 2'-naphthyl carbons (Table 1) are tentatively assigned for C-2, C-3 and C-9 and C-10. These assignments are based on the carbon resonances in 2-naphthylaldehyde[10]. C-2, C-9 and C10 carbons are quaternary of low intensity and the most
deshielded. The ten carbons of the naphthyl group for each complex and the ligand each show a different chemical shift except the 126.9ppm resonance of the nickel complex which gave twice the intensity of the other peaks. The C-3 resonance (ortho) occurs at high field. All the cobalt complexes (COL3) have a cis(fac) configuration. Since the ligand is in unsymmetrical, only one resonance is expected for a cis configuration for each type of carbon. A trans(mer) configuration having nonequivalent carbon sites would give a spectrum having
(s
/s
o o
trans(mer)
cis(fac)
three resonances for each carbon. The larger dipole moments of Co(Sthtf)3 (7.14D)[5] and Co(Snpff)3 (6.90D) [11] also support a cis(fac) structure. While it was not possible from dipole moment studies to distinguish between facial or meridional-octahedral configurations for Co(Sthdf)~ (4.95D), this 13C NMR study confirms its facial (cis) octahedral structure in CDC1314]. The large dipole moment of the NiL2 complexes sug-
A comparative13Cand 19FNMR study of some nickel, zinc and cobalt monothio-@-diketonatecomplexes
1809
Table 2. 19FNMRchemicalshift data for metal complexesof RC(SH)=CHCOCFS(LHY Complex NIL2
ZnL2
CoL3
R
74 .Fd
3:5t(CH30)2C6H3
2!c4ti3s”
74.5
2!cl
74.7
OHJ~
4!C2HgC6H4
J6.ld
4LC2H60C6H4
J6.od
3:4:5'(CH30)3CgH2
76.ld
2k4H3sb
76.1
2k,0ttJC
76.0
4+i5Oc6H4
J5.ld
3:4:61(Cti30)3C6H2
J6.2d
zk4H3sb
75.1
2!cl
75.1
OHJ~
Geometry
GF3
e&-square
planar
tetrahedral
fat-octahedral
'ppm upfield from WC13 bC4H3S-thierlyl 'CIOHJ-naphthyl ddata taken from ref. 2
gests a c&square planar configuration whereas a transsquare planar configuration would have a smaller dipole moment [4,5]. The still smaller dipole moment values for tetrahedral the ZnLl support a complexes geometry[4,12]. It is apparent that square planar and octahedral complexes of these ligands give a cis arrangement as the most stable configuration in the solid state and in solution. All of the zinc complexes gave IR bands (cm-‘) at cu. 1550 (C-O stretch 1500 (C-C stretch), 1400 (C-H bending), 1250(C-S stretch), 1130 (C-F stretch), 805 (C-H out of plane plus C-S stretch), 430 (Zn-0 stretch), 360 (Zn-S stretch)[lf, 141. The CF, substituents and the thiocarbonyl of the diketonate ligand have been shown to lower the ring frequencies which has also been used to support the quasi-aromatic character of these chelates [8, IS]. The 19F NMR spectra1 data complexes of the ligand RC(SH)=CHCOCF, are displayed in Table 2. As previously noted the organic substituent (thienyl and naphthy]) is not an important factor in the chemical shift, rather, the metals complexed give a good correlation with chemical shift data. For comparative purposes previous data are also included for the CF, substituents monothio+-diketonate chelates[2]. The chemical shift data indicates the order of decreasing field strength: NiLz > CoL, > ZnL,. This is the inverse order of 13CNMR chemical shift data for the thiocarbonyl and carbonyl carbons which also agrees with our previous data[2]. The 19F NMR resonance of the Sthtf-H[9] and Snptf-H ligands occurred at - 74.5 and - 77.3 ppm, respectively.
The fluorine resonances of the naphthyl complexes are more deshielded but the fluorine resonances of the thienyl complexes are more shielded with respect to their ligand resonances. The fluorine resonances of the NiL2, Znh and CoLp complexes of the ligand 2’-C4H$(CS)=CHCOCHF2 which were recorded at - 123.3, - 124.5and - 123.1ppm; respectively, were all more deshielded than the fluorine resonance of the protonated ligand (Sthdf-H) at - 125.1ppm. Finally, our previous Y! NMR study of various monothio-/I-diketonate ligands supports the view that the enol form of the ligand dominates in solution[9]. This study included the Sthdf-H and Sthtf-H ligands and now the 13C NMR spectrum of l,l,l-tritIuoro4mercapto-4-(2’naphthyl)but-3-en-2-one (Snptf-H) indicates the enol form as also being the major tautomer in solution. Only one thiocarbonyl and carbonyl carbon resonance and no ring ethylene carbon (CH,) was observed. This study supports the ‘H NMR work which has shown the predominance of the enol tautomer for monothio-fi-diketonate ligands [ 16,171. Acknowledgemenrs-This project was partially supported by the Marauette University Committee on Research and by a NSF Undergraduate Research Fellowship to D. Maas. The assistance of Mr. James W. Beery in taking the lsF NMR spectra is gratefully appreciated.
1. M. Das, therein.
Inorg.
RRFRRRNCRS Chim. Acta 36, 79 (1979) and refs. cited
1810
D.T. HAWORTH and D. L. MAAS
2. M. Das and D. T. Haworth, J. lnorg. Nucl. Chem. in press. 3. S. E. Livingstone and D. S. Moore, Austral. J. Chem. 29, 283 (1976). 4. M. Das, Transition Met. Chem. 5, 17 (1980). 5. M. Das, S. E. Livingstone, S. W. Filipczuk, J. W. Hayes and D. V. Radford, ~ Chem. Soe. Dalton 1409 (1974). 6. C. A. Wilkie and D. T. Haworth, J. Inorg. Nucl. Chem. 40, 195 (1978). 7. J. C. Hammel and J. A. S. Smith, J. Chem. $oe. (A) 1855 (1970). 8. C. L. Watkins and M. E. Harris, J. lnorg. Nucl. Chem. 40, 1765 (1978). 9. D. T. Haworth and M. Das, lnorg. Nucl. Chem. Lett. 16, 529 (1980). 10. 13C NMR spectra, Sadtler Research Laboratories, Philad-
delphia, Pennsylvania (1979). 11. D. S. Moore, B. Sc(Hons) thesis, University of New South Wales (1974). 12. S. W. Filipczuk, J. W. Hayes, D. V. Radford, M. Das and S. E. Livingstone, J. Chem. Soc. Soc. Dalton 886 (1975). 13. G. Dorange and J. E. Guerchais, Bull. Soc. Chim. 43 (1971). 14. K. C. Joshi and V. N. Pathak, J. lnorg. Nucl. Chem. 38, 3161 (1973). 15. R. C. Mehrotra, R. Bohra and D. P. Gaur, Metal ~Diketonates and Allied Derivatives, p. 239. Academic Press, New York (1978). 16. M. Cox and J. Darken, Coord. Chem. Rev. 7, 29 (1971). 17. R. C. Mehrotra, R. Bohra and D. P. Gaur, Metal flDiletonates and Allied Derivatives, p. 223. Academic Press, New York (1978).