- Email: [email protected]
Structures of α-tris (2,4-pentanedionato) ruthenium(III) and tris(3-bromo-2,4-pentanedionato) ruthenium(III)
STRUCTURES OF a-TRIS (2,4_PENTANEDIONATO) RUTHENIUM(II1) AND TRIS(3-BROMO-2,4_PENTANEDIONATO) RUTHENIUM(II1) T. S. KNOWLES,* Department
B. J. HOWLIN,
of Chemistry,
University
J. R. JONES and D. C. POVEY
of Surrey, Guildford,
Surrey GU2 5XH, U.K.
and C. A. AMODIO Department
of Physical
Sciences, St Mary’s College, Strawberry Middlesex TWl 4SX, U.K.
(Received
Hill, Twickenham,
16 June 1993 ; accepted 6 August 1993)
Abstract--Both title complexes have been synthesized and subsequently characterized by X-ray diffraction. Results available on the Cambridge Crystallographic Database (V.3) suggest that this is the first tris complex of a fully substituted O,O’-bonded acetylacetone to be characterized as a crystal structure from X-ray methods.
One step catalytic procedures which lead to the regiospecific introduction of the isotopes (‘H, ‘H) of hydrogen are becoming increasingly attractive methods for incorporating the label in a wide range of organic compounds, particularly those of interest to the pharmaceutical industry and until recently, the preferred catalyst for this has been hydrated rhodium(III) chloride.’ The discovery that ruthenium acetylacetonate complexes catalyse the regiospecific tritiation of aromatic carboxylates offers the dual advantages of improved specific activity and ease of chemical investigation owing to improved homogeneous retention. Only the ruthenium(II1) complex of this ligand is known to catalyse the reaction ; current work reflects modifications made to the catalyst structure and subsequent investigations in the potential for tritiation catalysis shown by homologous complexes. The apparently unique exhibition of catalytic behaviour by the ruthenium(III) complex suggested that structural considerations may be responsible, but this structure determination refutes such suggestions.
EXPERIMENTAL
There are two routes to complex I, both involving refluxing hydrated ruthenium(I11) chloride in aqueous solution. Route A proceeds via an ethanolic reduction to [Ru,C~,,]~- with the subsequent addition and reaction of the ligand with the cluster anion,’ whereas in route B’ the ligand is added directly to the solution of hot ruthenium(II1) chloride. RuC13.3H20
(A) reductive (FI) non-reductive
Ru( acac) 7 0)
*Author to whom correspondence should be addressed.
additmn addlhon
NBS. room tempcraturc
, Ru~3Br_acac~, (II)
The microcrystalline product from route A was crystallized over the course of several days from ethanol, giving ruby-red prisms which were suitable for crystallographic analysis. It was subsequently found that route B gave a cleaner reaction and product and a better yield ; thus, for the preparation of complex II the reaction of N-bromosuccinimide (NBS) with complex I prepared via route B was
2921
T. S. KNOWLES et nl.
2922
Table 1. Summary of key crystallographic data
Crystal description Crystal dimensions (mm) Data collection range (“) hkl ranges Total hkl hkl [I r ,3o (Z)] (%) Molecular formula Mr Crystal system Space group e(A) b(A) c(A) B(“) V(A’) Z
D(g cm-‘) flOO0) p (MO-K,) (cm-‘) R Rw
Complex I
Complex II
Ruby prism 0.5, 0.35, 0.075 126226 G16, o-18,0-20 3778 2332 (62) RuC,5HzOs 398.40 Orthorhombic Pbca 13.468 16.566 15.364 90.00 3427.9 8 1.544 1624 9.2 0.037 0.047
Hexagonal maroon plate 0.65, 0.60, 0.425, 0.05 126~25 O-15,0-11, -18 to +18 3815 2649 (69) RuGH&& 635.10 Monoclinic P2,ln 12.798 9.980 15.809 105.42 1946.6 4 2.170 1220 69.3 0.047 0.073
employed.4 Complex II gave maroon polyhedral plates when recrystallized from hot acetone. Both cell determinations and data collections were performed on an Enraf-Nonius CAD4 fourcircle diffractometer using graphite monochromated MO-K, radiation (2 = 0.71069 A). In both cases, 25 reflections taken from the angular range 13 > 13> 15” were used to determine the unit cell and no mechanical or chemical deterioration was observed in either case. Details of data collection and results for both complexes are summarized in Table 1. For complex I, bond lengths and angles are summarized in Table 2 and those of complex II in Table 3. Solution to crystal structures
Both structures were solved using the EnrafNonius Structure Determination package.’ Complex I. Solution of a three-dimensional Patterson synthesis gave a ruthenium position in the Harker plane (u, f, W) which refined to 34%. Iterative Fourier synthesis with isotropic refinement yielded a complete molecule with R = 8.8%. Subsequent anisotropic refinement, of the ruthenium only, with the Killean-Lawrence weighting scheme6 reduced R to 5.3%. Anisotropic refinement of the whole molecule converged to give a final R value of 3.7%. Figure 1 shows an ORTEP drawing of complex I.
Complex II. The direct methods program MULTAN7 was used to provide four heavy atom positions which refined to R = 32%. Further isotropic refinement with a single Fourier map yielded one ligand with R at 23% and then a single difference map provided the atomic complement necessary to complete the molecular skeleton, causing R to fall to 16%. Hydrogen atoms were added at calculated positions (bond length of 1 A) and anisotropic refinement of the whole molecule using the Killean-Lawrence weighting scheme reduced R to
Table 2. Selected bond lengths (A) and angles (“) for complex I Ru-O( 1) Ru-O(2) Ru-O(3) Ru-O(4) Ru-O(5) Ru-O(6)
1.998(3) 1.991(3) 2.008(3) 1.990(3) 2.005(3) 1.998(3)
0( 1)--Ru-O(2) O(3)-Ru-O(6) O(4)-Ru-O(5) O(l)-Ru-O(5) o(2)-Ru--0(3) O(4)-Ru-O(6)
93.7( 1) 92.5( 1) 92.8( 1) 178.5(l) 177.9(l) 178.8( 1)
Estimated parentheses.
standard
deviations
are in
2923
Strnctures of a-tris rutheninrn(II1) complexes Table 3. Selected bond lengths (A) and angles (“) for complex II Ru-O( I) Ru-O(2) Ru-O(3) Ru-O(4) Ru-O(5) Ru-O(6) C(l2jBr(l) C(36jBr(3) C(45jBr(S)
1.998(5) 1.988(5) 2.005(6) 1.994(5) 1.980(6) 2.005(5) 1.916(8) 1.913(9) 1.914(9)
0( ljRu-O(2) O(3)-Ru-O(6) 0(4jRu-O( 5) O(ljRu-O(5) 0(2jRu-O(3) 0(4jRu-O(6) C(It_C(I2jBr(I) C(2jC( 12jBr( 1) C(IjC(I2)--c(2) C(3jC(36jBr(3) C(6jC(36jBr(3) C(3jC(36HX6) C(4t-C(45jBr(5) C(5jC(45)-Br(5) C(4jC(45)-C(5)
91.3(2) 90.1(3) 92.0(2) 87.2(2) 89.4(2) 90.1(2) 116.8(6) 115.7(6) 127.5(8) 115.9(7) 115.8(6) 128.3(8) 116.2(6) 115.4(7) 128.4(8)
Br3 QJ
c22 1’
Fig. 2. ORTEP drawing of tris(3-bromo-2,4-pentanedionato) ruthenium(II1) with 50% probability thermal ellipsoids.
chelates of a variety of closely related metals were investigated ; none of these exhibited catalytic activity. A structural examination of those complexes tested, aided by the Cambridge Crystallographic Database (V.3),8 revealed distortion in the structure of the racemic ruthenium complex which has already been reported to crystallize in the Estimated standard deviations are in monoclinic space group P2’/c.9 parentheses. The redetermination of the structure of complex I resulted in the discovery of a dimorphic relationship which does not confirm the variation in rutheniumoxygen bond lengths previously recorded. As the 4.7%, at which the refinement converged. Figure 2 previous determination and labelling work both shows an ORTEP drawing of complex II. employed the commercially available compound, powder photographs were taken to investigate the RESULTS AND DISCUSSION relationship between these forms. The resulting photographs were identical, suggesting that strucFollowing the discovery of tritiation catalysis tural irregularities do not account for the observed shown by the ruthenium(III) complex, analogous catalytic effect. A dimorphic relationship in Pbca and P2Jc is observed in the acetylacetone complexes of vanadium(II1)” and manganese(II1) ;‘I by analogy, this is the a-form, the p-form being that previously reported. Furthermore, this ruthenium complex is isomorphic with the acetylacetone complexes of iron(III)‘2 and scandium(III).‘3 In both structures the mean ruthenium-oxygen bond distance is 2.00 A, which is within the range observed in other /I-diketonato complexes of ruthenium(III)‘4~‘s and in agreement with the racemic and enantiomeric forms.16 Evidence for pseudoaromatic character in both cases comes from the typical 0.01 8, shortening observed in ring carbon-carbon bonds in comparison to the terminal bonds. In complex II, the mean Fig. 1. ORTEP drawing of tris(2,4qentanedionato) carbon-carbon distance is 1.914(9) A, which is ruthenium(II1) with 50% probability thermal ellipsoids. carbon-bromine
T. S. KNOWLES et al.
comparable to those observed in other substituted bromoaromatic systems.17.‘8 The structure of II represents a new development in the chemistry of acetylacetonate complexes ; the only previous structural determinations are on the 3-methyl and 3-phenyl derivatives of copper(II).‘9,20 There appears to be a slight reduction in the external angles at the 3-position in comparison to the aforementioned methyl derivative, but substitution of hydrogen by bromine at the 3-position does not affect the geometry. Acknowledgements-We would like to thank Mr G. W. Smith for his kind guidance in overseeing the structural solutions, Dr J. H. Aupers for valuable discussion and helpful comments and Mr N. D. Wright for his instruction on the Cambridge Crystallographic Database.
REFERENCES
D. Hesk, J. R. Jones and W. S. Lockley, J. Lab. Comp. Radiopharm. 1990,28, 1427. A. Endo, K. Shimizu, G. P. Sato and M. Mukaida, Chem. Lett. 1984,437. R. Grobelny, B. Jezowska-Trzebiatowska .and W. Wojchiechowski, J. Znorg. Nucl: Chem., 1966, 28, 2715. 4. A. Endo, K. Shimizu and G. P. Sato, Chem. Lett. 1985,581. 5. B. A. Frenz and Associates, Enraf-Non&s Structure Determination Package. SDP Users Guide Version l.la Delft, The Netherlands (1985). 6. R. C. G. Killean and J. L. Lawrence, Acta Cryst. 1978, B25, 1750.
7. P. Main, S. E. Hull, L. Lessinger, G. Germain, J. P.
8.
9. 10. 11. 12. 13. 14.
15.
16. 17. 18. 19. 20.
Declerqc and M. M. Woolfson, Multan 78, A System of Computer Programs For The Automatic Solution of Crystal Structures From X-Ray Diffraction Data. University of York, U.K. and Louvain, Belgium (1978). F. H. Allen, S. A. Belard, M. D. Brice, B. A. Cartwright, A. Doubleday, H. Higgs, T. Hummelink, B. G. Hummelink-Peters, 0. Kennard, W. D. S. Motherwell, J. R. Rodgers and D. G. Watson, Acta Cryst. 1979, B35, 233 1. G. K.-J. Chao, R. L. Sime and R. J. Sime, Acta Cryst. 1973, B29,2845. B. Morosin and H. Montgomery, Acta Cryst. 1969, B25, 1354. J. P. Fackler and A. Avdeef, Znorg. Chem. 1974, 13, 1864. J. Iball and C. H. Morgan, Acta Cryst. 1967,23,239. T. J. Anderson, M. A. Neuman and G. A. Melson, Znorg. Chem. 1973, 12,927. S. Aynetchi, P. B. Hitchcock, E. A. Seddon, K. R. Seddon, Z. Yousif and A. Zalal, Znorg. Chim. Acta 1986, 113, L7. Y. Hoshino, Y. Yukawa, T. Maruyama, A. Endo, K. Shimizu and G. P. Sato, Znorg. Chim. Acta 1990, 174, 41. H. Matsuzawa, Y. Ohashi, Y. Kaizu and H. Kobayashi, Znorg. Chem. 1988, 27, 2891. W. Harrison, S. Rettig and J. Trotter, J. Chem. Sot., Dalton Trans. 1972, 1852. F. Toda, K. Tanaka and H. Ueda, Tetrahedron Lett. 1981,22,4669. I. Robertson and M. Truter, J. Chem. Sot. A 1967, 309. J. W. Carmichael, L. K. Steinrauf and R. L. Belford, J. Chem. Phys. 1965,43,3959.
B. J. HOWLIN,
of Chemistry,
University
J. R. JONES and D. C. POVEY
of Surrey, Guildford,
Surrey GU2 5XH, U.K.
and C. A. AMODIO Department
of Physical
Sciences, St Mary’s College, Strawberry Middlesex TWl 4SX, U.K.
(Received
Hill, Twickenham,
16 June 1993 ; accepted 6 August 1993)
Abstract--Both title complexes have been synthesized and subsequently characterized by X-ray diffraction. Results available on the Cambridge Crystallographic Database (V.3) suggest that this is the first tris complex of a fully substituted O,O’-bonded acetylacetone to be characterized as a crystal structure from X-ray methods.
One step catalytic procedures which lead to the regiospecific introduction of the isotopes (‘H, ‘H) of hydrogen are becoming increasingly attractive methods for incorporating the label in a wide range of organic compounds, particularly those of interest to the pharmaceutical industry and until recently, the preferred catalyst for this has been hydrated rhodium(III) chloride.’ The discovery that ruthenium acetylacetonate complexes catalyse the regiospecific tritiation of aromatic carboxylates offers the dual advantages of improved specific activity and ease of chemical investigation owing to improved homogeneous retention. Only the ruthenium(II1) complex of this ligand is known to catalyse the reaction ; current work reflects modifications made to the catalyst structure and subsequent investigations in the potential for tritiation catalysis shown by homologous complexes. The apparently unique exhibition of catalytic behaviour by the ruthenium(III) complex suggested that structural considerations may be responsible, but this structure determination refutes such suggestions.
EXPERIMENTAL
There are two routes to complex I, both involving refluxing hydrated ruthenium(I11) chloride in aqueous solution. Route A proceeds via an ethanolic reduction to [Ru,C~,,]~- with the subsequent addition and reaction of the ligand with the cluster anion,’ whereas in route B’ the ligand is added directly to the solution of hot ruthenium(II1) chloride. RuC13.3H20
(A) reductive (FI) non-reductive
Ru( acac) 7 0)
*Author to whom correspondence should be addressed.
additmn addlhon
NBS. room tempcraturc
, Ru~3Br_acac~, (II)
The microcrystalline product from route A was crystallized over the course of several days from ethanol, giving ruby-red prisms which were suitable for crystallographic analysis. It was subsequently found that route B gave a cleaner reaction and product and a better yield ; thus, for the preparation of complex II the reaction of N-bromosuccinimide (NBS) with complex I prepared via route B was
2921
T. S. KNOWLES et nl.
2922
Table 1. Summary of key crystallographic data
Crystal description Crystal dimensions (mm) Data collection range (“) hkl ranges Total hkl hkl [I r ,3o (Z)] (%) Molecular formula Mr Crystal system Space group e(A) b(A) c(A) B(“) V(A’) Z
D(g cm-‘) flOO0) p (MO-K,) (cm-‘) R Rw
Complex I
Complex II
Ruby prism 0.5, 0.35, 0.075 126226 G16, o-18,0-20 3778 2332 (62) RuC,5HzOs 398.40 Orthorhombic Pbca 13.468 16.566 15.364 90.00 3427.9 8 1.544 1624 9.2 0.037 0.047
Hexagonal maroon plate 0.65, 0.60, 0.425, 0.05 126~25 O-15,0-11, -18 to +18 3815 2649 (69) RuGH&& 635.10 Monoclinic P2,ln 12.798 9.980 15.809 105.42 1946.6 4 2.170 1220 69.3 0.047 0.073
employed.4 Complex II gave maroon polyhedral plates when recrystallized from hot acetone. Both cell determinations and data collections were performed on an Enraf-Nonius CAD4 fourcircle diffractometer using graphite monochromated MO-K, radiation (2 = 0.71069 A). In both cases, 25 reflections taken from the angular range 13 > 13> 15” were used to determine the unit cell and no mechanical or chemical deterioration was observed in either case. Details of data collection and results for both complexes are summarized in Table 1. For complex I, bond lengths and angles are summarized in Table 2 and those of complex II in Table 3. Solution to crystal structures
Both structures were solved using the EnrafNonius Structure Determination package.’ Complex I. Solution of a three-dimensional Patterson synthesis gave a ruthenium position in the Harker plane (u, f, W) which refined to 34%. Iterative Fourier synthesis with isotropic refinement yielded a complete molecule with R = 8.8%. Subsequent anisotropic refinement, of the ruthenium only, with the Killean-Lawrence weighting scheme6 reduced R to 5.3%. Anisotropic refinement of the whole molecule converged to give a final R value of 3.7%. Figure 1 shows an ORTEP drawing of complex I.
Complex II. The direct methods program MULTAN7 was used to provide four heavy atom positions which refined to R = 32%. Further isotropic refinement with a single Fourier map yielded one ligand with R at 23% and then a single difference map provided the atomic complement necessary to complete the molecular skeleton, causing R to fall to 16%. Hydrogen atoms were added at calculated positions (bond length of 1 A) and anisotropic refinement of the whole molecule using the Killean-Lawrence weighting scheme reduced R to
Table 2. Selected bond lengths (A) and angles (“) for complex I Ru-O( 1) Ru-O(2) Ru-O(3) Ru-O(4) Ru-O(5) Ru-O(6)
1.998(3) 1.991(3) 2.008(3) 1.990(3) 2.005(3) 1.998(3)
0( 1)--Ru-O(2) O(3)-Ru-O(6) O(4)-Ru-O(5) O(l)-Ru-O(5) o(2)-Ru--0(3) O(4)-Ru-O(6)
93.7( 1) 92.5( 1) 92.8( 1) 178.5(l) 177.9(l) 178.8( 1)
Estimated parentheses.
standard
deviations
are in
2923
Strnctures of a-tris rutheninrn(II1) complexes Table 3. Selected bond lengths (A) and angles (“) for complex II Ru-O( I) Ru-O(2) Ru-O(3) Ru-O(4) Ru-O(5) Ru-O(6) C(l2jBr(l) C(36jBr(3) C(45jBr(S)
1.998(5) 1.988(5) 2.005(6) 1.994(5) 1.980(6) 2.005(5) 1.916(8) 1.913(9) 1.914(9)
0( ljRu-O(2) O(3)-Ru-O(6) 0(4jRu-O( 5) O(ljRu-O(5) 0(2jRu-O(3) 0(4jRu-O(6) C(It_C(I2jBr(I) C(2jC( 12jBr( 1) C(IjC(I2)--c(2) C(3jC(36jBr(3) C(6jC(36jBr(3) C(3jC(36HX6) C(4t-C(45jBr(5) C(5jC(45)-Br(5) C(4jC(45)-C(5)
91.3(2) 90.1(3) 92.0(2) 87.2(2) 89.4(2) 90.1(2) 116.8(6) 115.7(6) 127.5(8) 115.9(7) 115.8(6) 128.3(8) 116.2(6) 115.4(7) 128.4(8)
Br3 QJ
c22 1’
Fig. 2. ORTEP drawing of tris(3-bromo-2,4-pentanedionato) ruthenium(II1) with 50% probability thermal ellipsoids.
chelates of a variety of closely related metals were investigated ; none of these exhibited catalytic activity. A structural examination of those complexes tested, aided by the Cambridge Crystallographic Database (V.3),8 revealed distortion in the structure of the racemic ruthenium complex which has already been reported to crystallize in the Estimated standard deviations are in monoclinic space group P2’/c.9 parentheses. The redetermination of the structure of complex I resulted in the discovery of a dimorphic relationship which does not confirm the variation in rutheniumoxygen bond lengths previously recorded. As the 4.7%, at which the refinement converged. Figure 2 previous determination and labelling work both shows an ORTEP drawing of complex II. employed the commercially available compound, powder photographs were taken to investigate the RESULTS AND DISCUSSION relationship between these forms. The resulting photographs were identical, suggesting that strucFollowing the discovery of tritiation catalysis tural irregularities do not account for the observed shown by the ruthenium(III) complex, analogous catalytic effect. A dimorphic relationship in Pbca and P2Jc is observed in the acetylacetone complexes of vanadium(II1)” and manganese(II1) ;‘I by analogy, this is the a-form, the p-form being that previously reported. Furthermore, this ruthenium complex is isomorphic with the acetylacetone complexes of iron(III)‘2 and scandium(III).‘3 In both structures the mean ruthenium-oxygen bond distance is 2.00 A, which is within the range observed in other /I-diketonato complexes of ruthenium(III)‘4~‘s and in agreement with the racemic and enantiomeric forms.16 Evidence for pseudoaromatic character in both cases comes from the typical 0.01 8, shortening observed in ring carbon-carbon bonds in comparison to the terminal bonds. In complex II, the mean Fig. 1. ORTEP drawing of tris(2,4qentanedionato) carbon-carbon distance is 1.914(9) A, which is ruthenium(II1) with 50% probability thermal ellipsoids. carbon-bromine
T. S. KNOWLES et al.
comparable to those observed in other substituted bromoaromatic systems.17.‘8 The structure of II represents a new development in the chemistry of acetylacetonate complexes ; the only previous structural determinations are on the 3-methyl and 3-phenyl derivatives of copper(II).‘9,20 There appears to be a slight reduction in the external angles at the 3-position in comparison to the aforementioned methyl derivative, but substitution of hydrogen by bromine at the 3-position does not affect the geometry. Acknowledgements-We would like to thank Mr G. W. Smith for his kind guidance in overseeing the structural solutions, Dr J. H. Aupers for valuable discussion and helpful comments and Mr N. D. Wright for his instruction on the Cambridge Crystallographic Database.
REFERENCES
D. Hesk, J. R. Jones and W. S. Lockley, J. Lab. Comp. Radiopharm. 1990,28, 1427. A. Endo, K. Shimizu, G. P. Sato and M. Mukaida, Chem. Lett. 1984,437. R. Grobelny, B. Jezowska-Trzebiatowska .and W. Wojchiechowski, J. Znorg. Nucl: Chem., 1966, 28, 2715. 4. A. Endo, K. Shimizu and G. P. Sato, Chem. Lett. 1985,581. 5. B. A. Frenz and Associates, Enraf-Non&s Structure Determination Package. SDP Users Guide Version l.la Delft, The Netherlands (1985). 6. R. C. G. Killean and J. L. Lawrence, Acta Cryst. 1978, B25, 1750.
7. P. Main, S. E. Hull, L. Lessinger, G. Germain, J. P.
8.
9. 10. 11. 12. 13. 14.
15.
16. 17. 18. 19. 20.
Declerqc and M. M. Woolfson, Multan 78, A System of Computer Programs For The Automatic Solution of Crystal Structures From X-Ray Diffraction Data. University of York, U.K. and Louvain, Belgium (1978). F. H. Allen, S. A. Belard, M. D. Brice, B. A. Cartwright, A. Doubleday, H. Higgs, T. Hummelink, B. G. Hummelink-Peters, 0. Kennard, W. D. S. Motherwell, J. R. Rodgers and D. G. Watson, Acta Cryst. 1979, B35, 233 1. G. K.-J. Chao, R. L. Sime and R. J. Sime, Acta Cryst. 1973, B29,2845. B. Morosin and H. Montgomery, Acta Cryst. 1969, B25, 1354. J. P. Fackler and A. Avdeef, Znorg. Chem. 1974, 13, 1864. J. Iball and C. H. Morgan, Acta Cryst. 1967,23,239. T. J. Anderson, M. A. Neuman and G. A. Melson, Znorg. Chem. 1973, 12,927. S. Aynetchi, P. B. Hitchcock, E. A. Seddon, K. R. Seddon, Z. Yousif and A. Zalal, Znorg. Chim. Acta 1986, 113, L7. Y. Hoshino, Y. Yukawa, T. Maruyama, A. Endo, K. Shimizu and G. P. Sato, Znorg. Chim. Acta 1990, 174, 41. H. Matsuzawa, Y. Ohashi, Y. Kaizu and H. Kobayashi, Znorg. Chem. 1988, 27, 2891. W. Harrison, S. Rettig and J. Trotter, J. Chem. Sot., Dalton Trans. 1972, 1852. F. Toda, K. Tanaka and H. Ueda, Tetrahedron Lett. 1981,22,4669. I. Robertson and M. Truter, J. Chem. Sot. A 1967, 309. J. W. Carmichael, L. K. Steinrauf and R. L. Belford, J. Chem. Phys. 1965,43,3959.