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Crown ether complexes of transition metals
0277~5387182/O.W/tl Pergamon Press Ltd.
Polyhedron Vol. I, No. 4. pp. 40!9-412. 1982 Printed in Great Britain.
CROWN ETHER COMPLEXES OF TRANSITION METALS SYNTHESIS AND CHARACTERIZATION OF COMPLEXES FORMED BETWEEN HYDRATED NICKEL (II) CHLORIDE AND THE CYCLIC POLYETHER 18 CROWN 6 JACQUES JARRIN* and FRANCOIS DAWANS Direction de Recherche Mat6riaux et Chimie Organique Appliqute, Institut Fran9ais du Petrole I,4 Avenue de Bois Preau, 92506Rueil Malmaison, Paris, France and FRANCIS ROBERT and YVES JEANNIN Laboratoire de Chimie des Mttaux de Transition ERA 608,4 Place Jussieu 75230Paris, France (Received 7 Ju/y 1981) Abstract-When hydrated nickel (II) chloride reacts with l&crown-6, two products are yielded: NiZC12(H20)s Clz. 18 C6 (compound I) and 2 NiClr. 2HrO. 18C6 (compound II). These complexes were separately isolated and characterized by infrared spectroscopy. The crystal structure of compound I is described. It crystallizes in the triclinic system with a = 8$28 (4) b = 9,693 (4). c = 10,616 (4) A, (I =55,74 (3), fi =6i,47 (3), ~=63,62 (3), V= 648,l A’, space group Pl. This structure shows an unusual conformation of the 18 crown 6 polyether (all the atoms of the crown are divided into two parallel planes separated by 1.1A) and a Ni2C12(H20)s unit containing the nickel atoms in the form of a bridged dinuclear unit. The cohesion of the structure is given by hydrogen bonds between the crown ether and the water molecules surrounding the dinickel unit. In a previously reported structure involving crown ether the hexa-aquo metal ions were present as monometallic units.
INTRODUCTION
In previously described structures of complexes between alkali and alkaline earth metal cations and cyclic polyethers,‘.’ the metal cation is generally located at the centre of the hole. In more recently described complexes of actinides and lanthanides3S5the metal is outside of the hole. Some structures have been determined for complexes of the transition metal cations within the first series. Sandwich-type structures are proposed when the metal is directly bonded to the crow&‘. Coordinated water molecules give more complicated structures in which the metal is not bonded to the crown. The cohesion of the structure is then give by hydrogen bonds between the water molecules in the aquated cation and the crown polyether.a’o The synthesis of (NiCl,)* 18C6 was briefly described by D. de Vosy but the experimental conditions were not given in detail. We obtained different reaction products using the below-mentioned conditions. So we are giving herein the synthesis of two new complexes of hydrated nickel (II) chloride with 18-crown-6. The infrared spectra of both products are compared with that of the crown polyether in the free state. Further, the structure of compound I is determined by X-ray diffraction. EXPERIMENTAL Synthesis of the complexes Triethylorthorformate, used by De Vos’ as a drying agent, reacts with water to yield ethanol and ethyl formate. According to the conditions described, we always obtained compounds containing coordinated methanol and ethanol molecules. In all cases these compounds were isolated as powders. By varying the *Author to whom correspondence should be addressed.
crystallization conditions we succeeded in obtaining two new crystalline complexes as follows: NiC12,6H20(2.38g, 10mmol) and 18C6 (2.64g, IOmmol) were mixed in 30 ml of an methanol/ethyl formate mixture (5: 1 volume ratio). With the addition of dried diethyl ether (about 75ml) the green solution became muddy. After several days, two different products are obtained: yellow-orange crystals (compound II) which are formed on the walls of the reaction vessel and a green oil (compound I) which is decanted and slowly crystallized from diethyl ether at room temperature. The use of ethyl formate is necessary, but the methanol/ethyl formate ratio, if it is between 5: 1 and 2 : 1,does not inthtence the nature of the reaction products. Table 1 shows the elemental analysis of the separately isolated complexes. Both compounds I and II are sensitive to atmospheric moisture and thus must be carefully stored under an argon atmosphere. The slight variations observed between the experimental and the theoretical values, particularly for compound I, are presumably due to the above-mentioned instability of the complexes. CHARACTERIZATIONOF THE COMPLEXES
IR spectroscopy The IR spectra of the compounds are determined by a Perkin-Elmer 457 recording spectrophotometer as dry nujol mulls between potassium bromide plates. X-Ray diffraction The cell constants were determined directly on a
diffractometer and refined from the least-squares fit of 28, x, Q for 36 high Bragg angle reflections. This gave the triclinic lattice arameters: a = 8.828 (4), 6 = 9.693 (4); c = 10.616 (4) Ap; a = 55.74 (3); /3 = 63.47 (3); y = 63.62 (3)“; V = 648.1 A’. The space group is Pi. Data were collected by an automatic CAD-3 EnrafNonius Diffractometer with MO& = 0.71069A)Zr filtered radiation in the B- 28 scan mode up to 2&,., = 409
JACQUES JARRIN et al.
410
Table 1. Elemental analysis of compounds I and II
[Ni2C12(H20)s]C12.18C6 compound I 2NiC12.2Hz0.18C6 compound II
%
C
H
Cl
0
Ni
Found talc. Found Calc.
21.8 21.6 24.1 25.7
5.9 6.0 5.0 5.0
23.6 21.2 28.5 25.4
31.2* 33.6 24.6 22.9
17.5 17.6 21.4 21.0
*Calculated by difference.
50”. The scan range varied according to A0 = 0.70 + 0.34 tg 8. 1301 reflections with I 2 3c~(I)were used for further calculations. The intensities were corrected for the Lorentz and polarization factors but not for absorption (pAMa= 19.3cm-‘) The structure was solved by direct methods (Multan”)-isotropic and then anisotropic full matrix leastsquares refinement gave R = 0,086. At this stage, alternate Fourier syntheses and least-squares refinement were used to locate all hydrogen atoms. In the last leastsquares cycles a weighting scheme is used with the form w = (325.0-1.857 Fo)-’ for Foc85.0 and w= (100.0to.7 Fo) for Foa 85.0. The final R values are Rw= R = (211Fol - IFcll)/ZIFol= 0.045 and (Pw(jFol - IFcl)‘/Zw Fo )“2 = 0.059.t The atomic scattering factors were taken from Infernational Tables for X-Ray Crystallography.” The real and imaginary parts of the anomalous dispersion were taken into account for nickel and chlorine atoms.
1600 1666
1466 1200 1000
600
800
406
Fig. 1. IR spectra of; (a) compound I [Ni2C12(H20)s]ClZ * 18C6. (b) compound II 2NiC12.2H20 * lEC6.
RESULTSANDDISCUSSION IR spectroscopy
The spectra of compounds I and II are compared with the one of the pure ll-crown-6 polyether previously described by Charpin.13 As shown in Fig. 1, the absorptions at 3500-3150 and 1635cm-’ frequencies are attributed to water molecules involved in a complicated set of hydrogen bonds.“’ The spectra of both compounds show the characteristic absorptions of 18-crownd, but the absorption frequencies are slightly displaced, thus proving complex formation. The absorptions between 1030 and 1080cm-’ in the spectrum of complex II probably indicate a crown ether configuration similar to that observed with the free state. They are not mentioned in the previously described complexes. The spectrum of compound I in the 12501350cm-’ frequency range is similar to that of (MnX2)2. 18C6. 8H20 described by M.E. Farago.” X-Ray dijfraction
This compound presents a chain structure. The [Ni2C12(H,0),]2’ and 18C6 groups are alternatively bonded by hydrogen bonds. Free chloride ions are also hydrogen bonded to the water molecules surrounding two neighbouring dinickel units (Fig. 2). Since the space group is centrosymmetric with one [Ni2C12(H20)s]C12.18C6 group in the unit cell, this implies that both the ether and the [Ni2C12(HZ0)8]2+ group lie on inversion centers (Fig 2).
tAtomic co-ordinates, thermal parameters and lists of Fo/Fc values have been deposited as supplementary material with the Editor, from whom copies are available on request. Atomic co-ordinates have also been deposited with the Cambridge Crystallographic Data Centre.
Fig. 2. Hydrogen bonding.
The [Ni2C12(H20)s]2+
This unit is formed by two edges sharing octahedra around Ni with the chlorine atoms at each end of the common edge. Four water molecules on each nickel atom complete the octahedron. The Ni-Cl distances are respectively 2.403 A and 2.420 A, which agree with those found in the [Ni2ClJ- ion’6.‘7 No significant variance is observed concerning bond angles and distances (Table 2 and 3). The water molecules are repelled by the Cl atoms, with Cl-Ni-0 bond angles higher than 0-Ni-0 ones (93.3 and 87.1”respectively). All hydrogen atoms of the water molecules participate in the hydrogen bonds. The hydrogen atoms of the water molecules which are not involved in hydrogen bonds with the crown have hydrogen bonds with the free chlorine atom (Fig. 2). The 18-crown-6 polyether.
The bond angles and the distances do not differ from those usually found in other similar structures.‘3V’b22On the contrary a conformational analysis shows some big
Crown ether complexes of transition metals
411
Table 2. Interatomic distances in A (the e.s.d.) in parentheses refer to last decimal places) NCCl(1) Ni-Cl’(l) Ni-O(1) Ni-O(2) NC0(3) Ni-O(4)
2.403(2) 2.420(3) 2.068(8) 2.067(7) 2.05q6) 2.07q7)
1.433(12) 1.425(14) 1.425(12) 1.432(12) 1.424(11) 1.430(14) 1X35(16) 1.498(15) 1.502(14)
oc(WC(2) oc(W(3) oc(2kc(4) oc(2XC(S) W3Wl) W3W(6) C(0-W) C(3W4) CWX9
Table 3. Bond angles in @)(The e.s.d. in parentheses refer to last decimal places) Cl(l)-Ni-Cl’(l) Cl(l)-Ni-O(1) Cl(I)-Ni-O(2) Cl(I)-Ni-q3) Cl(lkNi-O(4) Cl’(l)-Ni-O(l) Cl’(lbNi-q2) Cl’(l)-Ni-O(3) c(1)s(2HMl) C(2WAl)_C(3) O,(lW3)_C(4) C(3tW4WA2) C(4HM2W5)
85.12(8) 93.2(2) 94.8(2) 178.3(2) 91.9(2) 92.3(2) 92.5(2) 95.0(2) 109.4(8) 111.1(7) 108.7(8) 108.5(S) 113.2(7)
Cl’(+Ni-O(4) o( l)_Ni-o(2) O( I)-Ni-O(3) O(1jNi-o(4) O(2)-Ni-@3) 0(2)_Ni-o(4) O(3)-Ni-o(4) Ni-Cl( I)-Ni Q(2)-c(5W(6) C(W(6)_0,(3) C(6)_0,(3tc(l) 0,(3)-c(lW(2)
176.1(2) 170.9(3) 85.q3) 85.3(3) 86.9(3) 90.2(3) 87.9(3) 94.88(9) 112.7(8) 115.4(8) 112.1(7) 109.5(e)
Fig. 4. Crown viewed perpendicular to the mean plane.
(Table 4). The atoms are not alternately above and below the mean plane of the crown. It can be described (Fig. 4) as a sequence of five atoms below (C(l), C(2), Oc(l), C(3), C(4)), two above (O@), C(5)) and two below (C(6), Oc(3)), and the reverse for the symmetry related ones. In this way, all the atoms of the crown are in two parallel planes, and the distance between these planes is 1.10 A (Fig. 4). The crown is thicker than in other similar structures. The 6 oxygen atoms of the crown have hydrogen bonds with the water molecules of the [Ni2C1,(H,0),]*’ units (Fig. 2). These bonds are alternately below and above the plane of the crown and roughly perpendicular to this plane. This may explain the unusual thickness of the crown and its peculiar conformation. The unusual conformation of the crown ether is related to the strong hydrogen network which assumes crystal packing in the three directions
differences
0
HI511
Fig. 3. The 18-crown-6polyether.
Table 4. Torsional angles in the crown (0) 72.6 - 173.7 173.3 -65.4 - 176.9 - 75.5 -56.1 - 68.4 177.1
CONCLUSIONS
The presence of polar oxygenated ligands such as water molecules around the metal causes an unfavorable competition with respect to crown ether ligation. So, 18-crown-6, which is a very flexible crown ether, is not bonded to the nickel atoms but is hydrogen bonded to the aquated cation [Ni2C12, (H20)J?’ The dinuclear unit were not observed in the previous reported structures of complexes between hydrated cations and crown ethers.“”
JACQUES JARRIN et al.
412
This investigation shows, once again, that the solventmetal interaction strongly influences the complexing. The IR spectrum of compound II is quite different, and if suitable crystals are prepared their crystal structure will be solved. Acknowledgements-The authors wish to thank Professors E. Marechal and S. Boileau (University of Paris VI) for fruitful discussions.
REFERENCEs ‘M. R. Truter, In Structure and Bonding Vol. 16. SpringerVerlag, Berlin (1973). ‘J. J. Christensen, J. Delbert, D. J. Eatough and R. M. Izatt, Chem. Rev. 1974,74, 351. ‘G. Folcher, P. Charpin, R. M. Costes, N. Keller and G. C. de Vilkxdi, Inorg. Chim. Acta 1979,38,87. ‘C. Bombieri and G. de Paoli, Inorg. Chim Acta 1976,L23, 18. ‘M. Ciampolini and N. Nardi, Inorg. Chim. Acta 1979,L9,32. 6A. C. L. Su and J. F. Weiher, Inorg. Chem. 1968,7, 176. ‘D. DeVos, J. Van Daalen, A. C. Knegt, Th. C. Van. Heyningen, L. P. Otto, M. W. Vonk, A. J. M. Wijsman and W. L. Driessen, J. Inorg. Nucl. Chem. 1975,37, 1319.
‘A. Knogel, J. Kopf, J. Gehler and G. Rudolf, berg. Nucf. Chem. Lett. 1978,14,61. 9. B. Vance Jr, E. M. Holt, C. G. Pierpont and S. L. Holt, Acta Cryst. 1980,B36, 150. ‘(‘I. B. Vance Jr. E. M. Holt, C. G. Pierpont and S. L. Holt, Acta. Cry&, 1980, BJ6, 153. “MULTAN: G. Germain. P. Main and M. M. Woolfson, Acta Crysf. 1971,A27,368. ‘*International Tables for X-Ray Crystallography Vol. 4, p. 71. Kynoch Press, Birmingham (1974). “P. Charpin, R. M. Costes, G. Folcher, P. Plurien, A. Navaza and C. de Rango, Inorg. Nucl. Chem. Lett. 1977,13,341. “K. Nakamoto in Infrared and Raman Spectra of Inorganic and Coordination Compounds. Wiley New York (1978). “M. E. Farago, Inorg. Chim. Acta 1977,25,71. ‘6v. L. Gocken, L. M. Valhxino and J. V. Quagliano, J. Am. Chem. Sot. 1970,92,303. “F. K. Rass and G. D. Shucky, J. Am. Chem. Sot. 1970,92,4538. ‘sJ. D. Dunitz and P. Seiler, Acta Cryst 1974,B30,2739. ‘%4. Dobler, J. D. Dunitz and P. Seiler, Acta Cryst. 1974,B30, 2741. ‘9. Seiler. M. Dobler and J. D. Dunitz, Acta Cryst. 1974,B30, 2744. *‘M. Dobler and P. Phizackerley, Acta Crysl. 1974,B30, 2746. 22M.Dobler and P. Phizackerley, Acta Cryst. 1974,B30, 2748.
Polyhedron Vol. I, No. 4. pp. 40!9-412. 1982 Printed in Great Britain.
CROWN ETHER COMPLEXES OF TRANSITION METALS SYNTHESIS AND CHARACTERIZATION OF COMPLEXES FORMED BETWEEN HYDRATED NICKEL (II) CHLORIDE AND THE CYCLIC POLYETHER 18 CROWN 6 JACQUES JARRIN* and FRANCOIS DAWANS Direction de Recherche Mat6riaux et Chimie Organique Appliqute, Institut Fran9ais du Petrole I,4 Avenue de Bois Preau, 92506Rueil Malmaison, Paris, France and FRANCIS ROBERT and YVES JEANNIN Laboratoire de Chimie des Mttaux de Transition ERA 608,4 Place Jussieu 75230Paris, France (Received 7 Ju/y 1981) Abstract-When hydrated nickel (II) chloride reacts with l&crown-6, two products are yielded: NiZC12(H20)s Clz. 18 C6 (compound I) and 2 NiClr. 2HrO. 18C6 (compound II). These complexes were separately isolated and characterized by infrared spectroscopy. The crystal structure of compound I is described. It crystallizes in the triclinic system with a = 8$28 (4) b = 9,693 (4). c = 10,616 (4) A, (I =55,74 (3), fi =6i,47 (3), ~=63,62 (3), V= 648,l A’, space group Pl. This structure shows an unusual conformation of the 18 crown 6 polyether (all the atoms of the crown are divided into two parallel planes separated by 1.1A) and a Ni2C12(H20)s unit containing the nickel atoms in the form of a bridged dinuclear unit. The cohesion of the structure is given by hydrogen bonds between the crown ether and the water molecules surrounding the dinickel unit. In a previously reported structure involving crown ether the hexa-aquo metal ions were present as monometallic units.
INTRODUCTION
In previously described structures of complexes between alkali and alkaline earth metal cations and cyclic polyethers,‘.’ the metal cation is generally located at the centre of the hole. In more recently described complexes of actinides and lanthanides3S5the metal is outside of the hole. Some structures have been determined for complexes of the transition metal cations within the first series. Sandwich-type structures are proposed when the metal is directly bonded to the crow&‘. Coordinated water molecules give more complicated structures in which the metal is not bonded to the crown. The cohesion of the structure is then give by hydrogen bonds between the water molecules in the aquated cation and the crown polyether.a’o The synthesis of (NiCl,)* 18C6 was briefly described by D. de Vosy but the experimental conditions were not given in detail. We obtained different reaction products using the below-mentioned conditions. So we are giving herein the synthesis of two new complexes of hydrated nickel (II) chloride with 18-crown-6. The infrared spectra of both products are compared with that of the crown polyether in the free state. Further, the structure of compound I is determined by X-ray diffraction. EXPERIMENTAL Synthesis of the complexes Triethylorthorformate, used by De Vos’ as a drying agent, reacts with water to yield ethanol and ethyl formate. According to the conditions described, we always obtained compounds containing coordinated methanol and ethanol molecules. In all cases these compounds were isolated as powders. By varying the *Author to whom correspondence should be addressed.
crystallization conditions we succeeded in obtaining two new crystalline complexes as follows: NiC12,6H20(2.38g, 10mmol) and 18C6 (2.64g, IOmmol) were mixed in 30 ml of an methanol/ethyl formate mixture (5: 1 volume ratio). With the addition of dried diethyl ether (about 75ml) the green solution became muddy. After several days, two different products are obtained: yellow-orange crystals (compound II) which are formed on the walls of the reaction vessel and a green oil (compound I) which is decanted and slowly crystallized from diethyl ether at room temperature. The use of ethyl formate is necessary, but the methanol/ethyl formate ratio, if it is between 5: 1 and 2 : 1,does not inthtence the nature of the reaction products. Table 1 shows the elemental analysis of the separately isolated complexes. Both compounds I and II are sensitive to atmospheric moisture and thus must be carefully stored under an argon atmosphere. The slight variations observed between the experimental and the theoretical values, particularly for compound I, are presumably due to the above-mentioned instability of the complexes. CHARACTERIZATIONOF THE COMPLEXES
IR spectroscopy The IR spectra of the compounds are determined by a Perkin-Elmer 457 recording spectrophotometer as dry nujol mulls between potassium bromide plates. X-Ray diffraction The cell constants were determined directly on a
diffractometer and refined from the least-squares fit of 28, x, Q for 36 high Bragg angle reflections. This gave the triclinic lattice arameters: a = 8.828 (4), 6 = 9.693 (4); c = 10.616 (4) Ap; a = 55.74 (3); /3 = 63.47 (3); y = 63.62 (3)“; V = 648.1 A’. The space group is Pi. Data were collected by an automatic CAD-3 EnrafNonius Diffractometer with MO& = 0.71069A)Zr filtered radiation in the B- 28 scan mode up to 2&,., = 409
JACQUES JARRIN et al.
410
Table 1. Elemental analysis of compounds I and II
[Ni2C12(H20)s]C12.18C6 compound I 2NiC12.2Hz0.18C6 compound II
%
C
H
Cl
0
Ni
Found talc. Found Calc.
21.8 21.6 24.1 25.7
5.9 6.0 5.0 5.0
23.6 21.2 28.5 25.4
31.2* 33.6 24.6 22.9
17.5 17.6 21.4 21.0
*Calculated by difference.
50”. The scan range varied according to A0 = 0.70 + 0.34 tg 8. 1301 reflections with I 2 3c~(I)were used for further calculations. The intensities were corrected for the Lorentz and polarization factors but not for absorption (pAMa= 19.3cm-‘) The structure was solved by direct methods (Multan”)-isotropic and then anisotropic full matrix leastsquares refinement gave R = 0,086. At this stage, alternate Fourier syntheses and least-squares refinement were used to locate all hydrogen atoms. In the last leastsquares cycles a weighting scheme is used with the form w = (325.0-1.857 Fo)-’ for Foc85.0 and w= (100.0to.7 Fo) for Foa 85.0. The final R values are Rw= R = (211Fol - IFcll)/ZIFol= 0.045 and (Pw(jFol - IFcl)‘/Zw Fo )“2 = 0.059.t The atomic scattering factors were taken from Infernational Tables for X-Ray Crystallography.” The real and imaginary parts of the anomalous dispersion were taken into account for nickel and chlorine atoms.
1600 1666
1466 1200 1000
600
800
406
Fig. 1. IR spectra of; (a) compound I [Ni2C12(H20)s]ClZ * 18C6. (b) compound II 2NiC12.2H20 * lEC6.
RESULTSANDDISCUSSION IR spectroscopy
The spectra of compounds I and II are compared with the one of the pure ll-crown-6 polyether previously described by Charpin.13 As shown in Fig. 1, the absorptions at 3500-3150 and 1635cm-’ frequencies are attributed to water molecules involved in a complicated set of hydrogen bonds.“’ The spectra of both compounds show the characteristic absorptions of 18-crownd, but the absorption frequencies are slightly displaced, thus proving complex formation. The absorptions between 1030 and 1080cm-’ in the spectrum of complex II probably indicate a crown ether configuration similar to that observed with the free state. They are not mentioned in the previously described complexes. The spectrum of compound I in the 12501350cm-’ frequency range is similar to that of (MnX2)2. 18C6. 8H20 described by M.E. Farago.” X-Ray dijfraction
This compound presents a chain structure. The [Ni2C12(H,0),]2’ and 18C6 groups are alternatively bonded by hydrogen bonds. Free chloride ions are also hydrogen bonded to the water molecules surrounding two neighbouring dinickel units (Fig. 2). Since the space group is centrosymmetric with one [Ni2C12(H20)s]C12.18C6 group in the unit cell, this implies that both the ether and the [Ni2C12(HZ0)8]2+ group lie on inversion centers (Fig 2).
tAtomic co-ordinates, thermal parameters and lists of Fo/Fc values have been deposited as supplementary material with the Editor, from whom copies are available on request. Atomic co-ordinates have also been deposited with the Cambridge Crystallographic Data Centre.
Fig. 2. Hydrogen bonding.
The [Ni2C12(H20)s]2+
This unit is formed by two edges sharing octahedra around Ni with the chlorine atoms at each end of the common edge. Four water molecules on each nickel atom complete the octahedron. The Ni-Cl distances are respectively 2.403 A and 2.420 A, which agree with those found in the [Ni2ClJ- ion’6.‘7 No significant variance is observed concerning bond angles and distances (Table 2 and 3). The water molecules are repelled by the Cl atoms, with Cl-Ni-0 bond angles higher than 0-Ni-0 ones (93.3 and 87.1”respectively). All hydrogen atoms of the water molecules participate in the hydrogen bonds. The hydrogen atoms of the water molecules which are not involved in hydrogen bonds with the crown have hydrogen bonds with the free chlorine atom (Fig. 2). The 18-crown-6 polyether.
The bond angles and the distances do not differ from those usually found in other similar structures.‘3V’b22On the contrary a conformational analysis shows some big
Crown ether complexes of transition metals
411
Table 2. Interatomic distances in A (the e.s.d.) in parentheses refer to last decimal places) NCCl(1) Ni-Cl’(l) Ni-O(1) Ni-O(2) NC0(3) Ni-O(4)
2.403(2) 2.420(3) 2.068(8) 2.067(7) 2.05q6) 2.07q7)
1.433(12) 1.425(14) 1.425(12) 1.432(12) 1.424(11) 1.430(14) 1X35(16) 1.498(15) 1.502(14)
oc(WC(2) oc(W(3) oc(2kc(4) oc(2XC(S) W3Wl) W3W(6) C(0-W) C(3W4) CWX9
Table 3. Bond angles in @)(The e.s.d. in parentheses refer to last decimal places) Cl(l)-Ni-Cl’(l) Cl(l)-Ni-O(1) Cl(I)-Ni-O(2) Cl(I)-Ni-q3) Cl(lkNi-O(4) Cl’(l)-Ni-O(l) Cl’(lbNi-q2) Cl’(l)-Ni-O(3) c(1)s(2HMl) C(2WAl)_C(3) O,(lW3)_C(4) C(3tW4WA2) C(4HM2W5)
85.12(8) 93.2(2) 94.8(2) 178.3(2) 91.9(2) 92.3(2) 92.5(2) 95.0(2) 109.4(8) 111.1(7) 108.7(8) 108.5(S) 113.2(7)
Cl’(+Ni-O(4) o( l)_Ni-o(2) O( I)-Ni-O(3) O(1jNi-o(4) O(2)-Ni-@3) 0(2)_Ni-o(4) O(3)-Ni-o(4) Ni-Cl( I)-Ni Q(2)-c(5W(6) C(W(6)_0,(3) C(6)_0,(3tc(l) 0,(3)-c(lW(2)
176.1(2) 170.9(3) 85.q3) 85.3(3) 86.9(3) 90.2(3) 87.9(3) 94.88(9) 112.7(8) 115.4(8) 112.1(7) 109.5(e)
Fig. 4. Crown viewed perpendicular to the mean plane.
(Table 4). The atoms are not alternately above and below the mean plane of the crown. It can be described (Fig. 4) as a sequence of five atoms below (C(l), C(2), Oc(l), C(3), C(4)), two above (O@), C(5)) and two below (C(6), Oc(3)), and the reverse for the symmetry related ones. In this way, all the atoms of the crown are in two parallel planes, and the distance between these planes is 1.10 A (Fig. 4). The crown is thicker than in other similar structures. The 6 oxygen atoms of the crown have hydrogen bonds with the water molecules of the [Ni2C1,(H,0),]*’ units (Fig. 2). These bonds are alternately below and above the plane of the crown and roughly perpendicular to this plane. This may explain the unusual thickness of the crown and its peculiar conformation. The unusual conformation of the crown ether is related to the strong hydrogen network which assumes crystal packing in the three directions
differences
0
HI511
Fig. 3. The 18-crown-6polyether.
Table 4. Torsional angles in the crown (0) 72.6 - 173.7 173.3 -65.4 - 176.9 - 75.5 -56.1 - 68.4 177.1
CONCLUSIONS
The presence of polar oxygenated ligands such as water molecules around the metal causes an unfavorable competition with respect to crown ether ligation. So, 18-crown-6, which is a very flexible crown ether, is not bonded to the nickel atoms but is hydrogen bonded to the aquated cation [Ni2C12, (H20)J?’ The dinuclear unit were not observed in the previous reported structures of complexes between hydrated cations and crown ethers.“”
JACQUES JARRIN et al.
412
This investigation shows, once again, that the solventmetal interaction strongly influences the complexing. The IR spectrum of compound II is quite different, and if suitable crystals are prepared their crystal structure will be solved. Acknowledgements-The authors wish to thank Professors E. Marechal and S. Boileau (University of Paris VI) for fruitful discussions.
REFERENCEs ‘M. R. Truter, In Structure and Bonding Vol. 16. SpringerVerlag, Berlin (1973). ‘J. J. Christensen, J. Delbert, D. J. Eatough and R. M. Izatt, Chem. Rev. 1974,74, 351. ‘G. Folcher, P. Charpin, R. M. Costes, N. Keller and G. C. de Vilkxdi, Inorg. Chim. Acta 1979,38,87. ‘C. Bombieri and G. de Paoli, Inorg. Chim Acta 1976,L23, 18. ‘M. Ciampolini and N. Nardi, Inorg. Chim. Acta 1979,L9,32. 6A. C. L. Su and J. F. Weiher, Inorg. Chem. 1968,7, 176. ‘D. DeVos, J. Van Daalen, A. C. Knegt, Th. C. Van. Heyningen, L. P. Otto, M. W. Vonk, A. J. M. Wijsman and W. L. Driessen, J. Inorg. Nucl. Chem. 1975,37, 1319.
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