782 Correspondence Inorganic Chemistry

We conclude that although it may be possible to With regard to the Co-X stretching mode, Shiman-
prepare salts of [ReCk]3- under suitable conditions, ouchi and Nakagawa calculated the following stretching-
the existing claim5 to such a preparation is invalid. force constants (mdynes/A.): X(Co-F), 2.00; K
All pressure reactions were carried out in Pyrex glass (Co-Cl), 1.97; X(Co-Br), 2.53; and A (Co-I), 2.00.
tubes contained in steel bombs using an autoclave For [Co(NH3)5X]2+ these data require assignment of the
rocking unit. Co-X stretching mode as follows: F-, 504 and 493
Ammonium perrhenate (0.02 M) and ammonium cm.-1; Cl-, 487 and 479 cm.-1; Br-, 487 cm.-1;
chloride (0.04 M) in concentrated hydrochloric acid and I-, 428 cm.-1. That the Co-X bond order should
(40 ml.) were heated for 1.5 hr. with hydrogen at 150° follow the trend Co-Br, Co-I, Co-Cl5 is subject to
and an initial pressure of 100 atm. The products, question on the basis of a simple electronegativity
large green octahedra, red-brown octahedra, and small argument that is supported by recent nuclear quadru-
yellow crystals, were filtered, washed with concen- pole resonance studies of metal-halogen complexes6
trated hydrochloric acid and ethanol, and dried under and a far-infrared spectral study of tetrahalometal-
vacuum. ates.7 Data from the latter reference show that the
Using identical conditions, potassium perrhenate bond order is not Co-Br, Co-I, Co-Cl, but rather Co-Cl,
M) and potassium chloride (0.004 M) in con- Co-Br, Co-I as expected. Also, there is no apparent
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(0.002
centrated hydrochloric acid (5 ml.) yielded large green reason for two absorption bands for the single non-
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octahedra and small yellow crystals. degenerate Co-X stretching motion in [Co(NH3)6X]2+,
except the possibility of lattice coupling, in view of the
Acknowledgment. —We are grateful to the U. S.
Atomic Energy Commission for financial support. reported crystal structure8 of [Co(NH3)6Cl]Cl2.9 Re-
cent work7'10·11 on the Co-Cl stretching mode in
Department of Chemistry F. A. Cotton [CoCl4]2- led to assignments which, together with data
Massachusetts Institute of Technology B. F. G. Johnson
on Pd-Cl and Pt-Cl stretching motions,12 lead us to the
Cambridge 39, Massachusetts
conclusion that the 290 cm.-1 band in [Co(NH8)4Ck]Cl,
Received February 6, 1964
and the 283 cm.-1 band in [Co(NH3)6Cl]Br2 and
[Co(NH3)5Cl](N03)2, are due to the Co-Cl stretching
vibration. Accordingly, it must follow that the Co-Br
and Co-I modes lie below 250 cm,-1, which is supported
The Infrared Spectra of Ammines
by the recent work of Sabatini and Sacconi.7
of Cobalt(III) Chloride With regard to the Co-N stretching vibrations,
Sir: Shimanouchi and Nakagawa assigned the (Co-N)
Use of infrared spectra in the 700-200 cm.-1 region to Flu stretching mode in [Co(NH3)6]3+ at 464 cm.-1.
establish the identity of certain thermal decomposition Both they and Nakamoto, et al., have published spectra
products of [Co(NH3)e]Cl3, [Co(NH3)6C1]C12, and for [Co(NH8)6]I3 that are somewhat different,4·13 and
trans- [Co(NH3)4Cl2]Cl1 has led to a re-examination of the spectra obtained by the latter for [ ( 3)6]03,
the spectra of these three ammines2 and a re-evaluation [Co(NH3)6]Br3, and [Co(NH3)e]I3 focus attention on
of the assignments previously proposed for absorptions the crystal structure of each complex and the three
in the Csl region.3 While our spectral data are in weak bands at 450-500 cm.-1. The chloride and bro-
generally good agreement with those of Shimanouchi mide are monoclinic and the iodide is cubic.14 The
and Nakagawa,4 we believe that their conclusions with space group for the iodide is Oh6-F4/m32/m, with
regard to the Co-X and Co-N stretching vibrations Z = 4. Hence the Co3+ ion in [Co(NH3)6]3+ resides
require reconsideration. at a lattice site of Oh symmetry, and therefore the
In their study of the spectra of [Co(NH3)6]X3 (X = selection rules operative are those associated with the
Br", I-), [Co(NH8)6X]2+ (X F-, Cl-, Br-, I-), and
=
Oh point group.15-17 Thus, if the three weak bands
trans-[Co(NH8)4X2] + (X Cl-, Br-), Shimanouchi
= observed for the chloride and bromide are the com-
and Nakagawa assumed that the NH3 ligand behaved
(5) The Co-F is not compared in view of its recognized anomalous
as a dynamic group. This permitted a normal co- behavior.
case

ordinate analysis of these systems and allowed the (6) D. Nakamura, K. Ito, and M. Kubo, Inorg. Chem., 2, 61 (1963), and
mathematical treatment to be that of a seven-body pertinent references therein cited.
(7) A. Sabatini and L. Sacconi, J. Am. Chem. Soc., 86, 17 (1964).
problem. As a result, interactions (coupling) between (8) Y. Shigeta, Y. Komiyama, and H. Kuroya, Bull. Chem. Soc. Japan,
36- 1159 (1963).
the low frequency (below 900 cm.-1) vibrations of NHS
(9) Crystalline [Co(NHa)sCl 1CU is orthorhombic, having a CalYtypc
and the Co-N skeleton had to be ignored or assumed lattice. The space group is Pnma-I)2iiir>, with Z, =
4, thus placing the
[CoíNtLOsCl]-f in general positions.
negligible; this would appear to be an unsupported Í10) 1). M. Adams, J. Chalí, J. M. Davidson, and. .j. Gerratl, J. Chem.
condition. Soc., 2189 (1963).
(11) R. J. H. Clark and T. M, Dunn, ibid., 1198 (1963).
(1) G. W. Watt, Inorg. Chem, 3, 325 (1664). (12) E. G. Brame, Jr., Dissertation, University of Wisconsin, 1957.
(2) Measured as Nujol mulls using a Beckman IR-7 infrared spectro- (13) K. Nakamoto, Y. Morimoto, and J. Funito, Proceedings of the 7th
photometer in conjunction with a Beckman long wave length (CsT) inter- International Conference on Coordination Chemistry, Almqvist & Wiksell,
change. A.B.. Uppsala, Sweden, 1962, pp. 14-16.
(3) For review and references see: K. Nakamoto, “Infrared Spectra of (14) M. Gimenez-Huguet, Dissertation Abstr., 22, 2209 (1962).
Inorganic and Coordination Compounds,” John Wiley and Sons, Inc., New (15) R. S. Halford, J. Chem. Phys., 14, 8 (1946).
York, N. Y., 1963, pp. 143-151. (16) H. Winston and R. S. Halford, ibid., 17, 607 (1949).
(4) T. Shimanouchi and I. Nakagawa, Spectrochim. Acta, 18, 89 (1962). (17) D. F. Hornig, ibid., 16, 1063 (1948).
Vol. 3, No. 5, May, 1964 Book Reviews 783

ponents of the F iu species, which have been split owing spectra of appropriate complexes below 200 cm.-1
to the monoclinic environment, then a single band of and undertake a complete (as possible) normal co-
reasonable intensity would be expected in the spectrum ordinate analysis.
of the iodide. According to Nakamoto, et al., this is not
Acknowledgment.—This work was supported by
the case, and the spectrum obtained by Shimanouchi the United States Atomic Energy Commission and
and Nakagawa therefore imposes an indeterminate the Robert A. Welch Foundation.
answer.
Department of Chemistry George W. Watt
In view of these uncertainties, we suggest that the The University of Texas Donald S. Klett
nature of the Co-N stretching and deformation Austin, Texas 78712
modes remains to be resolved. We plan to observe the Received January 2, 1964

Book Reviews
Chromatographic Methods. By R. Stock and C. B. F. Rice, The last chapter describes eighteen model experiments based on
Department of Chemistry and Biology, College of Technology, the authors’ experience in teaching a course on chromatography.
Liverpool. Chapman and Hall Ltd., 37 Essex Street, London The experiments were chosen to give an example of each of the
W. C. 2. 1963. viii + 206 pp. 13.5 X 21.6 cm. Price, 40 s. main procedures and demonstrate the principles involved. There
The importance of chromatography to chemistry is readily are frequent references to earlier discussions that are germane to

apparent from its phenomenal growth and widespread use. the various experiments. For reasons of simplicity, paper
There are many books that deal with special types of chromatog- chromatographic experiments are the most numerous. There are
raphy, but considerably fewer that attempt to cover the spectrum. two experiments in gas chromatography that merit special com-
The appearance of a book with such a general title, therefore, ment. For the laboratory without gas chromatography equip-
might be expected to elicit interest from several sectors. This ment, the authors have thoughtfully described a simple appara-
book is an introductory treatment of chromatography, with tus, attributed to Cowan and Sugihara, which can be quickly as-
primary emphasis on techniques. It is intended principally for sembled from glass tubing and cleverly makes use of the eye as a
advanced undergraduates, but will also be of value to chemists detector. A second experiment requires a conventional apparatus
who want an introduction to the chromatographic techniques of the type now available in most laboratories. The student is
with which they are unfamiliar. asked to perform a variety of separations and to determine the
The first chapter gives a short and excellent classification of efficiency of the column by measurement of HETP values.
chromatographic processes and an introduction to the principles Aside from the minor objections noted earlier, the book is
of chromatography. Partition and adsorption methods are written clearly and concisely. It is well referenced at the end of
compared and the advantages of each discussed. After classify- each chapter and has a valuable bibliography following the
ing the techniques according to phenomenon, i.e., adsorption vs. Appendix. The volume gives an excellent treatment of the prac-
partition, and giving a breakdown depending on the physical tical aspects of chromatography and will be welcomed as a teach-
states of the stationary and mobile phases, the authors choose in ing aid. It must be recognized, however, as introductory in
the remainder of the book to discuss the topics according to scope; therefore it will be necessary for those anticipating the use
similarities in techniques. In Chapter 2, for example, they dis- of chromatography in their research to supplement their reading
cuss all types of liquid-phase column chromatography including by reference to more comprehensive works.
liquid-solid, liquid-liquid, and ion-exchange processes. Aerospace Research Laboratories Robert E. Sievers
The longest and most detailed chapters deal with paper and
Wright-Patterson Air Force Base, Ohio
gas chromatography. The chapter on paper chromatography
presents methods of development (ascending, descending, and
horizontal), selection and preparation of solvent and paper,
and methods of detection and identification of the separated
components. In the same chapter there are brief discussions of The Constitution of Glasses. A Dynamic Interpretation.
thin-layer chromatography and zone electrophoresis. The latter, Volume I. By Woldemar A. Weyl and Evelyn Chostner
though not strictly a chromatographic method, was included be- Marboe. Interscience Publishers, 440 Park Avenue South,
cause the techniques are closely related to those in paper chroma- New York 16, N. Y. 1962. xix + 427 pp. 15 X 23 cm. Price,
tography. In the chapter on gas chromatography, the section $16.00.
entitled “Inorganic Separations’’ will be of special interest to the Volume I of this two-volume series is subtitled “Fundamentals
inorganic chemist. The number and variety of studies of the Structure of Inorganic Liquids and Solids.’’ In keeping
reported is indicative of the recent intense research in inorganic with this subtitle, some ten or eleven of its sixteen chapters are
applications of gas chromatography. The first portion of the devoted to a summary of the properties of condensed systems in
chapter is devoted to a description of techniques and apparatus, general and a discussion of forces and bonding in such systems.
and at the end of the chapter there is a discussion of the theory The remaining chapters deal with the glassy state, its formation
of chromatography. The placement of this all-important section and constitution, and experimental approaches to studying
at the end of the next to the last chapter could be criticized. constitution. The discussions are documented by some 300
It would have been better to present the discussion earlier. references. Both an extensive author index and a somewhat
On the whole, the explanations are clear, but an exception is abbreviated subject index are included.
found on p. 141 where the limitation of gas chromatography to The book is substantially a presentation of a case for a dynamic
volatile samples is discussed. It is correctly stated that the approach to glass formation as opposed to the structural approach
vapor pressure of substances to be separated need only be a few that stems from the classic studies of Zachariasen. To this end,
millimeters, but the accompanying explanation implies that the much emphasis is laid upon an electrostatic approach to bonding
ease of elution is a function of the sample size. in terms of extensions of the Fajans quanticule approach and in-