1394 Inorganic Chemistry, Vol. 17, No. 6, 1978
Gary J. Long and Peter J. Clarke
W. C. Hamilton, Acta Crystallogr., 18, 502 (1965). The formula [CO(H,O)~] [CoPhDTA] is assumed for the solid sample only because solution studies indicate the presence of the C O ( H ~ O ) ~ ~ + ion; see text. Clearly a detailed study of crystals of the substance is required in order to definitively determine the nature of the coordination polyhedra. (a) M. A. Porai-Koshits, A. I. Pozhidaev, and T. N. Polynova, Zh. Strukt. Khim.,15, 1 1 17 (1974). (b) For an interesting alternative method of classifying EDTA complexes see B. Lee, Inorg. Chem.. 11, 1072 (1972). C. K. Johnson, “ORTEP’, Report ORNL-3794, Oak Ridge National Laboratory, Oak Ridge, Tenn., 1965. At room temperature (21-25 “C) all the complexes exhibit magnetic moments per Co(I1) ion of 4.6-4.9 pB. Thus, all can be considered high-spin complexes at room temperature. All “twist angles” mentioned are defined as the mean of the three twist angles formed using terminal atoms N(lO)-N(20), O(I1)-0(41), and O(21)-O(31) calculated using the centroids of the two triangles to define the twist-axis direction and the centroid of the six ligand atoms as the origin. For details see M. A. Flandera and E. C. Lingafelter, Inorg. Chem., 15, 750 (1976). T. N. Polynova, N. P. Bel’Skaya, D. Tyurk de Garciya Banos, M. A. Porai-Koshits, and L. I. Martynenko, Zh. Strukr. Khim.,11, 164 (1970). N. V. Novozhilova, T. N. Polynova, M. A. Porai-Koshits, N. I. Pechurova, L. I. Martynenko, and A. Khadi, Z h . Strukt. Khim., 14, 745 (1973). S. J. Rettig and J. Trotter, Can. J . Chem., 51, 1303 (1973). A. I. Pozhidaev, T. N. Polynova, M. A. Porai-Koshits, and N. N. Neronova, Zh. Strukr. Khim.,14, 570 (1973). N.V . Novozhilova, T. N. Polynova, M. A. Porai-Koshits, and L. 1. Martynenko, Zh. Strukt. Khim., 8, 553 (1967). M. D. Lind, M. J. Hamor, T. A. Hamor, and J. L. Hoard, Inorg. Chem., 3, 34 (1964). Ya. M.Nesterova, T. N. Polynova, L. I. Martynenko, and N. I. Pechurova, Z h . Strukt. Khim., 12, 1110 (1971). A. I. Pozhidaev, T. N. Polynova, M . A. Porai-Koshits, and V. A. Logvinenko, Zh. Strukt. Khim., 14, 746 (1973). J. L. Hoard, B. Pedersen, S. Richards, and J. V. Silverton, J . A m . Chem. Soc., 83, 3533 (1961).
(33) T. M. Polynova, N. Ti.Anan’eva, M. A. Porai-Koshits, L. I. Martynenko, and N. I. Pechurova, Zh. Strukt. Khim.. 12, 335 (1971). (34) F. P. van Remoortere, J. J. Flynn, and F. P. Boer, Inorg. Chem., 10, 2313 (1971). (35) G. H. Cohen and J. L. Hoard, J . A m . Chem. Soc., 88, 3228 (1966). (36) In this work the conclusionsabout hexadentate (six- or seven-coordinate) EDTA4- complexes do not include the Sn”EDTA4- complex reported by F. P. van Remoortere, J. J. Flynn, F. P. Boer, and P. P. Korth, Inorg. Chem., 10,1511 (1971). Becauseone site in the mrdination polyhedron is apparently occupied by a lone pair from the tin atom, this complex does not fit into either the hexadentate, six-coordinate or hexadentate, seven-coordinate classification. (37) D. L. Kepert, Inorg. Chem., 11, 1561 (1972). (38) The crystal-field calculationswere performed in the manner of Companion and Komarynsky, J . Chem. Educ., 41,257 (1964). The six donor atoms of PhDTA4- were represented by 1- charges and the coordinates of the charges were computed as indicated in the text. (39) W. C. E. Higginson and B. Samuel, J . Chem. SOC.A , 1579 (1970). (40) T. R. Bhat and M. Krishnamurthy, J. Inorg. Nucl. Chem., 25, 1147 (1963). (41) R. G. Wilkins and R. E. Yelin, J . A m . Chem. Soc., 92, 1191 (1970). (42) J. A. Neal and N. J. Rose, Inorg. Chem., 12, 1226 (1973). (43) K. Nakamoto, “Infrared Spectra of Inorganic and Coordination Compounds”, Wiley, New York, N.Y., 1963. (44) J. P. Hunt, Washington State University, Pullman, Wash., private communication. (45) B. N. Figgis, “Introduction to Ligand Fields”, Interscience, New York, N.Y., 1966. (46) A. B. P. Lever, Ad/:. Chem. Ser., No. 62, 430 (1967). (47) W. C. E. Higginson, J . Chem. Soc., 2761 (1962). (48) R. A. Haines and B. E. Douglas, Inorg. Chem., 4, 452 (1965). (49) G. S. Smith and J. L. Hoard, J . A m . Chem. SOC.,81, 556 (1959). (50) G. D. Fallon and B. M. Gatehouse, Acta Crystallogr., Sect. B., 30, 1987 (1974). (51) S. J. Lippard, H. Schugar, and C. Walling, Inorg. Chem., 6, 1825 (1967). (52) A. B. P. Lever, “Inorganic Electronic Spectroscopy”, Elsevier,New York, h-.Y., 1968.
Contribution from the Department of Chemistry, University of Missouri-Rolla, Rolla, Missouri 65401, a n d the Chemical Crystallography Laboratory, Oxford University, Oxford OX 1 3QR, England
Crystal and Molecular Structures of trans-Tetrakis(pyridine)dichloroiron(II), -nickel(II), and -cobalt(II) and trans-Tetrakis(pyridine)dichloroiron(II) Monohydrate G A R Y J. L O N G * and PETER J. C L A R K E
Received July 6, 1977 T h e crystal and molecular structures of Fe(py),C12, Co(pyj4C12, Ni(pyj4CI2, a n d Fe(pyj4C12.H20have been determined from three-dimensional x-ray diffraction data collected on a four-circle diffractometer. T h e first three compounds crystallize in the tetragonal I.ll/acd space group with unit cell parameters of ca. 15.9 8, for a and ca. 17.1 A for 6 and a volume of ca. 4350 A’. Fe(py),Clz.H2O crystallizes in t h e monoclinic P 2 , / c space group with a = 9.384 (6) A, 6 = 16.766 (4) A, c = 16.342 (9) A, /3 = 121.497 (25)’, and I/= 2192.2 (1.2) A,’ T h e structures were solved by Patterson and Fourier methods a n d refined where feasible by full-matrix least-squares procedures. All nonhydrogen atoms were refined with anisotropic thermal parameters and all pyridine hydrogen atoms were located by electron difference methods although more accurate positions were derived through geometric considerations; the resulting conventional R factors a r e 4.77,4.83, 4.98, and 3.88%,respectively. In each complex the metal coordinated in a trans fashion to two chloride ions and four pyridine molecules. T h e molecules, which possess 222 but not 4 symmetry, are oriented with their pseudotetragonal (CI-M-C1) axis normal to the tetragonal axis of the crystals. T h e individual molecules of M(py),ClZ a r e well isolated from each other with essentially no intermolecular contact distances of less than the sum of van der Waals radii. T h e one exception t o this is Fe(py),Cl2-H20 where the water molecule serves a s a presumably hydrogen-bonded bridge between two chloride ions in adjacent molecules. I n the anhydrous iron, cobalt, and nickel complexes the M-CI bond distances are 2.430 (3), 2.440 (2), and 2.437 (3) A, and the M-N bond distances a r e 2.229 (6), 2.183 (4), and 2.133 (4) A, respectively. T h e decrease in the M-N bond distance with increasing metal atomic number is attributed to the importance of the increasing number of tZga-bonding electrons in the metal ions. T h e relatively constant M-C1 bond distance is attributed to the constant number of a-bonding electrons in these metal ions. T h e dihedral angle between the plane of the coordinate nitrogen atoms and the pyridine ring is ca. 51’ in the anhydrous complexes. T h e increase of this dihedral angle above 45’ i s attributed either t o a pyridine hydrogen to chlorine hydrogen-bonded interaction or t o a hydrogen-carbon interaction on adjacent coordinated pyridine molecules.
is
Introduction There have been many with the which have electronic and magnetic properties of tetrakis(pyridine)-
* To whom correspondence should be addressed at the University of Missouri-Rolla. 0020-1669/78/1317-1394$01.00/0
metal(I1) chloride complexes. In several of these papers it has been assumed that the molecule possesses tetragonal symmetry with trans &loride ligands in the axial coordination positions and p y r i d i n e in the four e q u a t o r i a l positions. This is a reasonabie assumption in view bf the preiiminary x-ray structural results for Ni(py),Cl,-based on a two dimensional
0 1978 American C h e m i c a l Society
Tetrakis(pyridine)metal(II) Chloride Complexes
Inorganic Chemistry, Vol. 17, No. 6, 1978 1395
Table I. Crystal Parameters and Intensity Data
Formula Mol wt Crystal dimens, mm C&td class Space group a, A b., A C , 1$.
P , deg
v,A=
Fe(py),Cl, FeC H N C1 443.?640 0.80 X 0.36 X 0.18 Tetragonal 14,lacd, No. 142, origin on 1 15.945 (2)
CO(PY),Cl, CoC H N C1, 446.Y4d0 1.02 X 0.23 X 0.18 Tetragonal 14,lacd, No. 142, origin on 1 15.966 (2)
Ni(p~),Cl,~ NiC H N C1 446762420 0.89 X 0.30 X 0.18 Tetragonal 14,lacd, No. 142, origin on 1 15.920 (3)
17.287 (6)
17.153 (6)
17.046 (12)
4395.1 (2.7)
4372.5 (2.7)
8
8
4320.2 (4.8) 8 1.372 1.409 (1)
1.356 Calcd density, g cm-3 1.340 1.379 (1) 1.351 (1) Exptl density, g cm-3 Asymmetric unit Fe0.25C5H5NC10.5 Co0.15C5H5NC10.5 Mo KLY, Radiation MO K a , 0-60 0-60 20 limits, deg Absorp coeff, cm-' 9.6 10.7 Absorp cor None None Refined parameters 63 63 686 Reflections obsd 533 914 Reflections unobsd 1133 4.83 Unwtd R factor 4.77 6.68 Wtd R factor 6.52 Crystal used corresponded to Ni,~97Fe,~o,(py),C1,with 0.42 wt % Fe (see text). refinement-obtained by Porai-Koshitz and Antsishkina9 and the isomorphism exhibited by the iron, cobalt, and nickel complexes.10 Unfortunately, although the early x-ray work indicated that the crystal class was tetragonal and of space group M l / a c d , the results were not accurate enough to d e termine whether the molecule also possessed tetragonal symmetry. Because of our interest" in the magnetically perturbed single-crystal Mossbauer spectra of these compounds-doped with 57Fe in the case of the cobalt and nickel complexes-we decided to determine the single-crystal x-ray structure of each of these salts. During the course of crystal preparation, a monohydrate of Fe(py),C12 was also obtained and its crystal structure is reported herein. A further incentive for this work was our interest in the details of the metal-ligand bonding as a function of metal ion and the accompanying changes in the electronic structure of the metal ion. In spite of the large number of studies on the electronic and magnetic properties of the various tetrakis(pyridine) complexes, there are relatively few complete x-ray structures reported. In addition to the above-mentioned structure, Porai-Koshitz and his co-workers12have also reported preliminary results on Ni(py),Br2 and C O ( ~ ~ ) , ( N C S )More ~ . recently, Sgtofte and Rasmussen have reported13 the structure of F ~ ( P ~ ) , ( N C S ) ~ and Hamm et al. have reported14 on Ni(py),12. The situation is somewhat better for bis(pyridine) compounds. The important early work of Dunitz15 on the pseudooctahedral polymeric C 0 ( p y ) ~ C 1and ~ C~(py)~Cl~-pseudo-one-dimensional magnetic systems- has recently been refined and extended to the low-temperature y form of C ~ ( p y ) ~ C byl ~ Clarke and Milledge.I6 Richards et al. have also determined the structurei7 of Mn(py),C12 and Morosin has refined and discussedis the structures of C ~ ( p y ) ~ and C l ~C ~ ( p y ) ~ Ball r~, of which possess the pseudooctahedral polymeric structure with bridging halide ligands. A studyIg of C O ( P ~ ) ~ ( N Crevealed S)~ a polymeric octahedral structure with two equivalent nitrogenand sulfur-bonded bridging thiocyanate ligands. A similar result" was found for C U ( ~ ~ ) , ( N C S ) In ~ . contrast, the structure of Zn(py),C12 was recently reported2' to contain a pseudotetrahedrally coordinated zinc ion. The only other type of pyridine complexes studied are C 0 ( p y ) , ( N 0 ~ ) ~and its analogous copper and zinc complex.22 A comparison of the
Ni0.25c5H5Nc10.5
Mo Ka, 0-60 11.6 Empirical 63 848 730 4.98 7.48
F ~ ( P Y ) ~"2 C 0 ~, FeC H N OC1, 460.?8$ 0.86 X 0.23 X 0.16 Monoclinic P2,lc, No. 14 9.384 (6) 16.766 (4) 16.342 (9) 121.497 (25) 2192.2 (1.2) 4 1.394 FeC,,H,,N,Cl,H,O Mo Ka, 0-50
9 .I None 250 1798 1946 3.88 4.53
relative metal-ligand bond distances in these complexes is used to relate the bonding to the nature of the electronic configuration of the metal.
Experimental Section Preparation. Each of the compounds was prepared by adding a solution of the hydrated metal(I1) chloride salt dissolved in methanol slowly to a solution of ca. 50% by volume of pyridine dissolved in methanol. The preparations of the iron compounds were carried out under a stream of nitrogen gas and with deoxygenated solvents to prevent oxidation of the iron(I1). In each case the complex immediately precipitated and was removed by filtration after being stirred about 1 h. The mother liquor was then allowed to evaporate slowly producing single crystals of M ( p ~ ) ~ cEvaporation l~. of the mother liquor containing Fe(py),C12 under nitrogen yielded anhydrous single crystals whereas evaporation in air yielded the monohydrate Fe( ~ y ) ~ C l ~ . HBecause ~ 0 . the nickel complex was also prepared for single-crystal Mossbauer effect studies, these crystals were doped with 0.42 wt % of iron-57. All compounds gave satisfactory C, H, and N analyses. Because the single crystals tend to lose pyridine from their surfaces, all crystals were immediately inserted, along with a small amount of mother liquor, into glass capillaries which were immediately sealed. All experimental densities were measured by flotation in mixtures of 1,l-dichloroethane and 1,2-dibromoethane by using a Westphal balance. Crystal Data. The approximate dimensions of the crystals used in this study are given in Table I.23 The crystals were all mounted with their c axes approximately coincident with the spindle axis. Preliminary studies of the x-ray diffraction patterns were made by means of Weissenberg and precession methods, by using Ni-filtered Cu Ka and Zr-filtered Mo K a radiations, respectively. The photographs obtained fit into two categories. The diffraction symmetry of the anhydrous compounds was 4/mmm and the systematic absences were hkl, h = k = I = 2n + 1; hkO, h ( k ) = 2n + 1; Okl, 1 ( k ) = 2n + 1; hkl ( l = 2n), 2h + 1 = 4n + 1, indicating that the space group was M,/acd. The Fe(py),Cl2.H10 crystals had diffraction symmetry 2/m and systematic absences h01, 1 = 2n + 1; OkO, k = 2n + 1, indicating space group P2!,. X-ray diffraction intensities were collected by means of a Hilger-Watts four-circle diffractometer with Mo Koc radiation (A 0.71069A) and a graphite monochromator (002). Unit cell parameters were determined by a least-squares methodz4from the positions of a number of automatically centered reflections. The parameters and their standard deviations are also given in Table I. Intensity data were collected by the w-20 scan technique with 50 steps of 0 . 0 2 O in
1396 Inorganic Chemistry, Vol. 17, No. 6, 1978
Gary J. Long and Peter J. Clarke
Table 11. Final Positional and Anisotropic Thermal (X l o 3 )Parameters for Nonhvdroeen Atomsa
0.0000 0.1078 (1) 0.0716 (4) 0.1098 (6) 0.1534 (7) 0.1597 (7) 0.1194 (5) 0.0767 (5)
0.2500 0.3578 (1) 0.1821 (4) 0.2225 (6) 0.1818 (7) 0.0967 (7) 0.0523 (6) 0.0987 (5)
0.1250 0.1250 0.0337 (3) -0.0238 (4) -0.0821 (5) -0.0801 (5) -0.0220 (5) 0.0328 (4)
0.0000 0.10826 (8) 0.0694 (3) 0.1078 (4) 0.1524 (5) 0.1580 (5) 0.1 182 (4) 0.0751 (4)
0.2500 0.35826 (8) 0.1828 (3) 0.2229 (4) 0.1818 (5) 0.0964 (5) 0.0547 (4) 0.0995 (4)
0.1250 0.1250 0.0349 -0.0227 -0.0796 -0.0773 -0.0195 0.0356
(2) (3) (4) (4) (4) (3)
0.0000 0.10823 (7) 0.0677 (2) 0.1065 (4) 0.1511 (4) 0.1567 (4) 0.1174 (4) 0.0741 (3)
0.2500 0.35823 (7) 0.1840 (2) 0.2243 (3) 0.1829 (4) 0.0978 (5) 0.0550 (3) 0.1004 (3)
0.1250 0.1250 0.0363 -0.0217 -0.0786 -0.0766 -0.0176 0.0380
(2) (3) (3) (3) (3) (3)
0.03888 (9) 0.2643 (2) -0.1905 (2) 0.1631 (5) 0.3283 (7) 0.4079 (8) 0.3161 (9) 0.1473 (9) 0.0743 (7) -0.0981 (5) -0.1184 (7) -0.2183 (7) -0.3022 (7) -0.2808 (7) -0.1785 (7) -0.0954 (5) -0.0142 (7) -0.0924 (9) -0.262 (1) -0.3480 (8) -0.2623 (7) 0.1749 (5) 0.2611 (7) 0.3472 (8) 0.3458 (8) 0.2595 (8) 0.1746 (7) 0.5542 (8)
0.15385 (9) 0.1779 (3) 0.1793 (4) 0.1381 (4) 0.0937 (4) 0.0921 (5) 0.1 343 (4) 0.3214 (2) 0.3996 (3) 0.4458 (4) 0.4107 (4) 0.3307 (4) 0.2879 (3) 0.3196 (3) 0.3648 (4) 0.4123 (5) 0.4146 (5) 0.3705 (5) 0.3229 (4) 0.1777 (2) 0.2116 (4) 0.1682 (4) 0.0867 (5) 0.0512 (4) 0.0975 (3) 0.0679 (4)
0.4716 (i) 0.3419 (1) 0.3414 (3) 0.3803 (4) 0.3423 (5) 0.2621 (5) 0.2210 (5) 0.2627 (4) 0.4566 (3) 0.4408 (4) 0.4598 (4) 0.4988 (5) 0.5177 (4) 0.4959 (4) 0.2663 (3) 0.2365 (4) 0.1563 (5) 0.1044 (5) 0.1329 (5) 0.2124 (4) 0.5394 (3) 0.6260 (4) 0.7096 (4) 0.7058 (5) 0.6176 (5) 0.5365 (4) 0.1524 (5)
46.7 (4) 58.1 (9) 62.0 (9) 6 3 (3) 79 (4) 108 (6) 1 0 3 (5) 112 (6) 89 (5) 46 (3) 52 (4) 64 (4) 8 8 (5) 89 (5) 60 (3) 68 (3) 108 (5) 140 (7) 142 (7) 126 (6) 82 (4) 5 0 (3) 70 (4) 104 (6) 109 (6) 59 (4) 54 (4)
a The anisotropic temperature factors (X l o 3 ) are of the form exp[-(h2a*’U,, t k 2 b * 2 U 2 2+ 1 2 ~ * 2 U 3 +32hka*b*U,z 2klb*c*U2 Solvent oxygen refined isotropically only; occupancy factor for solvent H,O is 0.76 (1).
31.
w . A t least two equivalents of each reflection were measured for the tetragonal crystals but only one for the monoclinic case. Integrated intensities were extracted from the measured profiles via the ordinate-analysis approachZ5taking the 30 consecutive data points yielding the maximum gross intensity as the peak and the remaining 20 data points as the background. A scale factor of 1.5 was therefore necessary to relate the measured background to the gross peak intensity. Differential absorption curves26were measured for several reflections with x setting angles close to 90°, but only in the case of Ni(py),C12 was the absorption found to be large enough to warrant application of a correction. Data processing and structure refinement were carried out by using the “crystals” system computer program2’ and the Oxford University ICL 1906A computer. The Lorentz-polarization correction was applied to the measured intensities, and the data were merged
+ 2hla*c*U,, +
to yield sets of unique reflections. Intensities less than 4u, where u was the standard deviation from counting statistics, were classed as unobserved and rejected. The structures were solved by Patterson and Fourier methods and refined where feasible by full-matrix least-squares calculations. For each structure, coordinates, scale factors, and isotropic temperature factors were refined until convergence, and hydrogen atoms were added in calculated positions. Further refinement of the scale factor and coordinates and anisotropic temperature factors for the nonhydrogen atoms yielded the final structural parameters given in Tables I1 and 111. Final cycles for the monoclinic Fe(py),C12.H20 structure, which had many more variable parameters than the others, were performed by using a block diagonal matrix approximation. The parameters were divided into seven blocks as follows: (1) all coordinates and the
Inorganic Chemistry, Vol. 17, No. 6,I978 1397
Tetrakis(pyridine)metal(II) Chloride Complexes Table 111. Final Positional Parameters for Hydrogen Atoms Atom
Y
X
z
Fe(py),Cl, (Vi,, = 0.090 A') 0.1086 0.2858 0.2139 0.1849 0.0620 0.1915 -0.0131 0.1225 0.0659 0.0431 CO(PY),C1, (Viso = 0.090 A') 0.2865 0.1065 0.2139 0.1817 0.0624 0.1916 -0.0115 0.1220 0.0668 0.0430 Ni(py),Cl, (Vi,, = 0.050 A') 0.2876 0.1048 0.2147 0.1796 0.0637 0.1910 -0.0106 0.1219 0.0676 0.0429 Fe(py),CI,.H,O (Vi,, = 0.050 A,) 0.2118 0.3977 0.1411 0.5327 0.0629 0.3712 0.0607 0.0766 -0.0498 0.1316 -0.0563 0.4265 -0.2304 0.5044 -0.3769 0.4429 -0.3382 0.3034 -0.1639 0.2294 0.1109 0.3637 -0.0252 0.4443 -0.3208 0.4495 -0.47 32 0.3721 -0.3280 0.2889 0.2713 0.2629 0.1965 0.4109 0.0544 0.4065 -0.0083 0.2583 0.0702 0.1102
-0.0242 -0.1246 -0.1217 -0.0176 0.0743 -0 .O 229 -0.1244 -0.1189 -0.0 143 0.0774
-0.0222 -0.1240 -0.1181 -0.0122 0.0802 0.4399 0.3741 0.2338 0.1609 0.2324 0.4138 0.4454 0.5128 0.5471 0.5100 0.2747 0.1365 0.0462 0.0960 0.2314 0.6302 0.7728 0.7662 0.6126 0.4726
isotropic temperature factor for the oxygen; (2) anisotropictemperature factors for Fe and C1; (3) scale factors and dummy overall isotropic temperature factors; (4-7) anisotropic temperature factors for each of the four pyridine rings. Atomic scattering factors were taken from ref 28, and anomalous dispersion corrections for respective metal and chlorine atoms were taken from ref 29. The function minimized was Cw(lFol Initially, w = 1 for all data, but toward the end of the refinement values of w were calculated from a polynomial function based on a Chebyshev series.30 The expression used for w was w = 1/ ~,lo""A,T,*(x), where n is the number of terms in the summation, A , are the coefficients of the Chebyshev series, T,*(x),and x is Fa/F,,,,, where F,,, is the maximum value of the observed structure factor. The number of terms, n, and the coefficients, A,, were determined such that zw(lFol - IFc1)2was approximately unity for the complete data set and for various subsets of data systematically chosen
Figure 1. A perspective view of Fe(py),Clz showing the molecular
geometry and atomic numbering.
Figure 2. A perspective view of Fe(py),C12-H20showing the molecular geometry and atomic numbering.
over ranges in lFal and (sin @)/A. The values of A, are given in Table IV.31 The observed and calculated structure factors are presented in Table V."
Results and Discussion The results of the structural analysis indicate that the compounds have the expected trans chloride geometry with the pyridine nitrogen atoms approximately in a plane containing the metal ion (see below). The structure of the anhydrous F e ( p ~ ) ~ C molecule l~ and the numbering scheme are shown in Figure 1. The structures of the cobalt and nickel complexes are essentially identical with that shown in Figure 1 and the same numbering scheme is used. The structure of the monohydrate, Fe(py),C12.H20, is shown in Figure 2 along with the numbering scheme. The basic structure of this complex is quite similar to that of the anhydrous complex; however, the presence of the water molecule has lowered the symmetry of the crystal and the molecule making the four
Table VI. Intramolecular Bond Distances (A) Fe(py),Cl, 2.430 (3) 2.229 (6) 1.331 (9) 1.332 (9) 2.417 (2) 2.257 (4) 1.333 (6) 1.328 (7) 1.382 (8) 1.354 (9) 1.359 (9) 1.386 (8)
2.444 (2) 2.1 83 (4) 1.329 (7) 1.333 (7)
2.437 (2) 2.133 (4) 1.330 (6) 1.335 (6)
1.385 (12) 1.361 (13) 1.386 (12) 1.382 (10)
Fe(py),Cl, 2.440 (2) 2.236 (4) 1.331 (6) 1.342 (6) 1.371 (7) 1.377 (8) 1.368 (9) 1.386 (7)
3.137 (7) 2.252 (4) 1.335 (7) 1.338 (6) 1.373 (8) 1.354 (9) 1.348 (9) 1.371 (8)
1.374 (9) 1.367 (10) 1.352 (10) 1.37 1 (8)
1.371 (8) 1.359 (9) 1.366 (9) 1.378 (7) 3.107 (7) 2.241 (4) 1.335 (7) 1.346 (7) 1.377 (8) 1.367 (9) 1.367 (9) 1.376 (8)
Gary J. Long and Peter J. Clarke
11398 Inorganic Chemistry, Vol. 17, No. 6, 1978
Table VIII. Least-Squares Planes and Dihedral Angles
Table VII. Bond Angles (deg) Fe(py),Cl,
CO(PY),C~,
N~(PY),C~,
M-NC(1) M-NC(5) C( 1) - N C (5 ) N-C(1)-C(2) C(l)-C(2)
