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MoIV in Aqueous Solutions The Trinuclear Cluster [MoIVO4F9]5 the First Species Isolated from Mineral Acid Solution.

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through basic Alox I). The mixture was then treated dropwise within 3 h with a solution of (11) (1 mmol) in 8 m L of
the relevant aforementioned solvent. After filtration
through celite the solution was treated with DBU (175 pL,
1.05 mmol) and then, after a further 30 min, the resulting
mixture was poured into water and extracted with CH2C12.
After separation of the aqueous phase the reaction solution was washed twice with water and once with saturated
NaCl solution. The organic phase, after drying over magnesium sulfate and careful removal of solvent, gave a yellow oil, which was rapidly chromatographed on ca. 15 g
MN-silica gel with CH2CI2/CH3OH(25 : 1).
Cycloaddition of (5). R2 = OEt, to olefins: CF3S03SiMe3
(310 pL, 1.72 mmol) was added to a solution of cyclohexene (760 pL, 7.50 mmol; distilled over Na) in dichloroethane or dichloromethane. A solution of (5). R2= OEt, (270
mg, 1.50 mmol) in 8 mL of one of the previously mentioned solbents was then added to the reaction mixture
dropwise within 3 h. After a total of 4 h the solution was
treated with DBU (260 pL, 1.75 mmol). After a further 30
min the mixture was poured into water and worked u p as
mentioned above. For separation, the yellow oil was rapidly chromatographed on ca. 40 g MN-silica gel with C H 2 /
C H 3 0 H , whereupon substantial amounts of (18) decomposed.
Received: September 26, 1980 [ Z 759 IE]
German version: Angew. Chem. 93, 491 (1981)
[I] R. R . Schmidt. Chem. Ber. 103, 3242 (1970). The salts of (I), X = C ,
Y = N"H, were prepared in sifu from N-(chloromethy1)benzamides and
SnCI,.
[2] a) U. M . Kempe. T. K . DasCupta. K . Blarr. P. Gygax, D. Felix. A . Eschenmoser. Helv. Chirn. Acta 55, 2188 (1972). The salts of ( l ) , X = N e ,
Y = CH,, were prepared from a-chloronitrones by chloride-elimination
with AgBF,; b) P. Gygax, 7: K . DasGupta, A . Esrhenrnoser. ibid. S5, 2205
(1972).
[3] M. Riediker. W.Graf; Helv. Chim. Acta 62, 205 (1979). The heterodienes
(Ic) were prepared in silu from epoxypropanalnitrones by CFS0,SiR; induced epoxide-opening. They show an analogous H-shift.
[41 From a mechanistic point of view it could be a stepwise [8+2]-DielsAlder reaction with inverseelectron demand; see J . Sauer. H. Weist, Angew. Chem. 74, 353 (1962); Angew. Chem. Int. Ed. Engl. I, 269 (1962).
MoIV in Aqueous Solutions:
The Trinuclear Cluster I M O ' ~ O ~-,
F~I~
the First Species Isolated from Mineral Acid Solution"]
A solution of Mo'" in aqueous H F was prepared by a
normal cation exchange
Addition of excess
N H 4 F allowed the isolation of deep red, in transmitted
light red, crystalline needles of
(NH&IMO~O~F,I.
N H ~ F . H z O (1)
which was characterized by elemental analysis, IR- and VISspectra (characteristic band in the solid state reflection spectrum at /2=525 nm) and by an X-ray crystal structure analysisf7I.In this way, the first successful isolation of a crystalline
substance from a mineral acid solution of Mo'" without addition of a complexing agent was achieved. The structure of the
anion corresponds to the B,-type of trinuclear electron-poor
transition metal clusterslbl, in which the metal atoms (Mo--Mo = 2.505 A) are surrounded by a distorted octahedron of oxygen and fluorine (Mo-F=2.034 A) and the central JMo(p?O)(p2-O),l-moiety [Mo-(+~-O)= 2.032, Mo-(p2-O)= 1.920 A]
can be considered as a distorted, incomplete cube (average
bond lengths in brackets). ( I ) is isostructural with the corresponding W-compound, which notably was obtained from an
aqueous solution of Wv by addition of HFL8](for an interpretation cf. L61).
The electronic spectrum of the aqueous H F solution of ( I )
also shows the VIS-band observed in the solid state spectrum.
The splitting of this band (doublet: A at ~ 5 1 8 B
, at =535
nm), as well as the time-dependence of the relative intensities
of A and B (following dissolution) and their dependence on
the concentration of acid, indicates that several species of the
are
present. The
type [ M O ~ O ~ F ~ - ~ ( H ~ O ) ~(2)
](~
- ' 'probably
F- H,O ligand exchange process cannot be identified significantly by a change of color, but only by a slight change in the
electronic spectrum (increase in the intensity of A relative to
B). These results, regarding the probable presence of Mo"'
species with a central Mo3O4cluster unit in mineral acid solutions, are clearly contrary to all previous results (Fig. I). This
n
n
W
Fig. 1. hlolecular structure of [Mo,04FJ- in crystals of ( I ) .
By Achim Miiller, Andreas Ruck, Mechthild Dartmann,
and Uta Reinsch- Vogelll*l
also corresponds to our most recent understanding of Mo'",
which shows a strong tendency to form trinuclear clusters (in
accord with the d2-configuration) in solutions containing no
Until 1973 it was assumed that acidic aqueous solutions
strong n-acceptor ligandsfbl. We have assigned the observed
containing Mo'" were not stablef2]("The only well-known
Mo'" species in aqueous solution is [MO(CN),]~-"~~"~). VIS-bands A and B, following an EHMO calculation, to transitions in the Mo,-cluster system (cf. also I@).
Following investigations carried out by Souchay (which
had been overlooked until 1973; cf.
and by Ardon and
P e r n i ~ k l it
~~
has
. ~now
~ , been clearly proven that Mo'" is stable in mineral acid solutions (the characteristic red color
is caused by the absorption band: ;1ca. 505 n m ; d M o c 6 0
dm3 m o l - ' c m - ' ) . From the results of numerous measurements using a variety of different methods, it was concluded that mono- or di-nuclear complexes are p r e ~ e n t ' ~ - ~ ] .
It had, however, already been suggested in a review articleL6]
that some results were more indicative of trinuclear
clusters.
[*I Prof. Dr. A. Muller, A. Ruck, M. Dartmann,
Procedure
A solution of Mo'", (from [MoCl6l3- and [MoOCI,]'-) prepared afterf4], is adsorbed on a cation exchange column
(Dowex 50 WX 2) and purified with 0.5 and 1 M ptoluenesulfonic acid (02-free) afterE4'.The exchanger is eluted with 10
crn' of a 40% aqueous solution of H F and ca. 20 cm3 H20.
NH4F (2 g) is added to the first 10 cm3 of the red eluate. Dark
red crystals of ( I ) precipitate (in certain cases only after slight
concentration of the solution by passing nitrogen over it).
Yield cu. 80%, relative to the Mo-content of the solution.
DipLChem. U. Reinsch-Vogell
Fakultat fur Chemie der Universitlt
Postfach 8640, D-4800 Bielefeld (Germany)
Angew. Chem. Inr. Ed. Engl. 20 (1981) No. 5
Received: June 30, 1980 [Z 761 IE]
supplemented: November 18, 1980
German version: Angew. Chem. 93, 493 (1981)
0 Verlag Chemie GmbH, 6940 Weinheim. 1981
0570-0833/81/05OS-483 S 02.50/0
483
[ I ] T h i s problem was a major topic of discussion at three international conferences
(Reading 1973. Oxford 1976, Ann Arbor 1979) on “The Chemistry and Uses of
Molybdenum”: cf. also [Z].
[2] a) G. P. Haight. D. R . Bosfon in P. C. H. Mitchell: Proceedings of the First International Conference on the Chemistry and Uses of Molybdenum, Climax Molybdenum Company, London 1973, p. 48; b) M. Ardon. A. Pernick in P. C. H.
Mirchell. A . Seaman: Proceedings of the Second International Conference on
the Chemistry and Uses of Molybdenum, Climax Molybdenum Company, London 1976, p. 206; J. Less-Common Met. 54, 233 (1977); c) E. I . Slfefei. Prog.
Inorg. Chem. 22, 1 (1977); d) M. Lamache. J. Less-Common Met. 39, 179
(1975); e) F. A . Coflon, G. Wrlkinsonr Advanced Inorganic Chemistry. 4th Ed.,
Wiley-Interscience, New York 1980; A . Bino. F. A . Cotton. 2. Dori. J. Am.
Chem. SOC. 100, 5252 (1978).
131 Th. Ramasami, R. S. Taylor. A . G. Sykes. J. Am. Chem. SOC.97,5918 (1975); M.
Ardon. A. Bino, G. Yahoo. ibid. 98, 2338 (1976).
141 M.Ardon. A. Pernick, J. Am. Chem. SOC.95,6871 (1973).
I51 S. P. Cramer, H. B. Gray. 2. Dori. A. Bino. J. Am. Chem. SOC. 101, 2770
(1979).
161 A. M d l e r . R. Josles. F A. Cotlon. Angew. Chem. 92,921 (1980); Angew. Chem.
Int. Ed. Engl. 19, 875 (1980).
I71 Space group P 2 J c ; Z = 4 ; a = 13.662(2), b=8.193(1), c= 15.355(2), +94.21( I)’;
3615 observed reflections (Syntex PZ,); R=0.037.
(81 R . Manes, K. Mennemann. 2. Anorg. Allg. Chem. 437, 175 (1977).
191 Note added upon supplementation: Recently published results on isotopic exon Mo‘”-containing solutions, which contain
change reactions (‘‘0/‘’0)
NCS -,also point to a trinuclear species; R. K. Murmann, M. E. Sheiton. J. Am.
Chem. SOC. 102, 3984 (1980).
BOOK R E V I E W S
Comprehensive Biochemistry. Edited by M . Florkin (deceased), A . Neuberger and L. L. M . van Deenen. Vol. 19,
Part B 1 : Protein Metabolism. Elsevier Publishing Company, Amsterdam 1980. xx, 528 pages, 64 figs., bound,
Dfl. 168.00.
This volume of “Comprehensive Biochemistry”“’ begins
with a disarming declaration: “The Editors were faced
with alternative possibilities: one either tried to deal with
the major topic in a comprehensive manner, but this would
have meant almost unavoidably a degree of superficiality
which was unacceptable.. .”. They therefore decided to
give progress reports on somewhat randomly chosen but
particularly topical areas of protein metabolism.
I n their chapter, V . M . Pain and M . J . Clernens manage
to summarize the present knowledge of the many components that take part in the protein synthesis machinery of
the eukaryotic cell, to describe the mechanisms of their interactions, and to give the most important aspects of the
regulation of translation. With the inclusion of more than
500 references u p to 1979 and building-on on a corresponding chapter in Volume 24 (1977), this has obviously
succeeded well. Just how long this information will remain
new in the rapidly evolving field is a question that occurs
time and again when using the whole work, which is evidently considered to be a long-term investment.
The sections by P. J. Garlick and D . J. Millward are devoted to the turnover of plasma proteins and enzymes in
the flowing equilibrium of continuous synthesis and degradation in various tissues and in the whole organism.
The first of these authors concentrated more on the regulation of the rates of these reactions in vivo and on the contribution this makes to the total nitrogen balance of an animal, the second on the various courses of degradation in
the muscles and liver. In these painstaking and well coordinated articles, too, more than 500 publications have been
worked into a clearly arranged and readable general presentation.
Protein metabolism and protein structure are closely entwined subjects. A . J . Bailey and D . J . Etherington were
evidently of the opinion that our knowledge of general
structural chemistry and of the metabolism of collagen and
elastin has now reached such a state that it deserved a really detailed presentation, and convinced the sympathetic
editors to allocate to them almost one-third of the book for
I*] Cf. Angew. Chem.
484
Int. Ed. Engl. 17, 873 (1978)
a thorough review. In spite of dealing with more than 800
references, they still regard this review as not exhaustive.
The main emphasis is placed on connective tissue biosynthesis during growth and on the mechanisms of degradation, thus providing more than just a basis for this research
field equally important to medicine and the food industry.
K . B. M . Reid offers a stimulating and understandable
resume to the complement system, a proteolytic cascade
system of a special kind. This complex defensive mechanism of higher organisms has many molecular special features, so that this chapter, too, will only be a snapshot from
the year 1979.
With its extensive literature reviews and sensible presentation by the authors, who mostly come from the close circle of one of the editors, this topical book will undoubtedly prove a useful new publication for users in the fields
of chemistry, biochemistry, pharmacology, and medicine.
This major volume supplements a field always deliberately
neglected in the main work, which has thus perhaps not always become “more comprehensible” but certainly “more
comprehensive”, in spite of the editors’ reservations.
L. Jaenicke [NB 540 IE]
Statistical Mechanics of the Liquid Surface. By C. A. Croxton. John Wiley and Sons, Chichester 1980. xi, 345
pages, bound, f 25.00.
Our understanding of the equilibrium properties of
atomic fluids has increased so much in recent years with
the help of statistical mechanics that a transition to complex systems appears to be realistic. The particular questions here are whether the principles of statistical mechanics can also be applied to the inhomogeneous region of the
liquid-gas interface, and if the familiar thermodynamic
concepts such as pressure, density, and chemical potential
can be extended to the phase interface. Since many properties of the liquid surface are excess-quantities, which record the change in the liquid’s properties on transition to
the surface, and consequently require knowledge of the
properties of the liquid, a statistical-mechanical description is difficult. Two quantities characterize the liquid-gaseous region: the density profile, which describes the
change in density perpendicularly to the liquid surface,
going from the density of the liquid to the density of its vapor, and the anisotropic pair distribution function, which
gives the probability of finding a second particle at a defiAngen, Chem. I n / . Ed. EngI
20 I I Y H I ) No. 5
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