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Diastereoisomers with Differing Bond Lengths Structure Analysis of the Diastereomeric Forms of -(1 2-Dichloro-1 2-diphenyldiphosphane)bis(pentacarbonylchromium).

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oacuo and the crude isocyanide (3) purified by distillation
or recrystallization.
Received: January 27, 1977 [Z 659 IE]
German version: Angew. Chem. 89, 267 (1977)
CAS Registry numbers:
( l a ) , 123-39-7; ( I b ) , 2425-74-3; ( I c ) , 766-93-8; ( I d ) , 6343-54-0; (le),
5470-34-8; ( I f ) . 3154-54-9; ( J g ) , 59490-41-4; (Z), 503-38-8; ( 3 a ) , 593-75-9;
( 3 b ) , 7188-38-7; ( 3 ~ )931-53-3;
,
( 3 d ) , 10340-91-7; ( 3 e ) . 10349-38-9; (3f),
39687-95-1; ( 3 g ) , 61752-36-1
[l] Review: I. Ugi, U . Fetrer, U . Eholzer, H . Knupfer, K . Offermann, Angew.
Chem. 77,492 (1965); Angew. Chem. Int. Ed. Engl. 4,472 (1965).
[2] I . Ugi, W Befz, U . Fetzer, K . Offermann, Chem. Ber. 94, 2814 (1961);
P . Hoffmann, G . Gokef, D. Marquarding, I . Ugi in I . U g i : Isonitrile
Chemistry. Academic Press, New York 1971, p. 9.
[3] H . C. Ramsperger, G . Waddington, J. Am. Chem. SOC.55, 214 (1933).
[4] K. M e y r , I. Ugi, Chem. Ber. 93, 239 (1960).
[5] D . Marquarding, P . Seidel, unpublished result.
[6] R . Urban, D. Marquarding, P . Seidel, A . Weinelt, I . Ugi, Chem. Ber.,
in press; see also R . Urban,Dissertation, Technische Universitat Miinchen
1975.
[7] G. Skorna, I. Ugi, Tetrahedron Lett., in press.
[8] D. A r k , H . Hagemann, P . Hofmann, I . Ugi, DAS 1668 100 (1968), Farbenfabriken Bayer.
Diastereoisomers with Differing Bond Lengths: Structure Analysis of the Diastereomeric Forms of p-(1,2Dichloro-l,2- diphenyldiphosphane)bis ( pentacarbonylchromium)[**]
By Gottjried Huttner, Peter Friedrich, Heinrich Willenberg,
and Hans-Dieter Miillery]
The distances between covalently bonded phosphorus atoms
deviate only slightly from an average value of 222 pm, regardless of the nature of the substituents attached to the phosphorus and its formal charge"]. It therefore appears surprising
that the P-P distance in P2F4 has recently been determined
as 228.1(6)pm[21.We have now found even longer P-P distances in transition metal complexes of 1,2-dichloro-1,2diphenyldiphosphane, which can be interpreted at least in part
as the result of steric interactions, as demonstrated by structural comparison of two diastereomeric diphosphane complexes.
The symmetricallysubstituted diphosphane Ph2PzCI2forms
the dinuclear complexes ( 1 ) with (C0)5Cr[31.The structures
of the meso form (I a) and of the racemate (1 b ) were determined by X-ray
(Fig. 1).
The P-P distance in the meso form (1 a ) is 229.ql)pm
and thus lies at the upper limit of the range hitherto observed
for the P-P bond lengths of diphosphane~[~.~]
and their
In the racemic form ( 1 b ) the P-P distance is increased
by 3.7pm to 232.7(6)pm; thus (I b ) exhibits the longest P-P
distance so far reported for diphosphanes.
Since ( l a ) and ( I b ) bear the same substituents at the
phosphorus, the difference in the P-P bond lengths can only
arise from steric interactions between the substituents which
have to adopt a less favorable arrangement in the racemate
(1 b ) (C, symmetry) than in the centrosymmetric meso form
(1 a) (Fig. 1).
Toour knowledge the compounds (1 a ) and (1 b ) constitute
the first pair of diastereoisomers for which significant differences have been observed in the central bond lengths.
Received: December 1, 1976;
revised: January 28, 1977 [Z 661 IE]
German version: Angew. Chem. 89,268 (1977)
[l] D . E. C. Corbridge: The Structural Chemistry of Phosphorus. Elsevier,
Amsterdam 1974.
[2] H . L. Hodges, L . S. Su, L. S . Bartefl, Inorg. Chem. J4, 599 (1975).
[3] G. Huttner, H . Willenberg, H.-D. Miilfer, unpublished.
[4] Measurement: SYNTEX-P21; solution: SYNTEX-XTL; ( 1 a ) : space
group PT, Z=1, 1379 independent reflections ( 1 2 3 4 , T=183K,
R I =0.037; ( J b ) : space group C2/c, Z=4 , 633 independent reflections
( I t 3 u ) , T=298K, R1=0.062.
[S] A survey is given in [I] and in Annu. Rep. Prog. Chem. Sect. A 72,
129 (I 976).
[6] G. Huttner, H.-D. Miilfer, T.: Bejenke, 0.Orama, Z. Naturforsch. 3 1 6 ,
1166(1976);J. A. J. Jarvis, R. H . B. Mais, P . G . Owston, D . 7: Thompson,
J. Chem. Soc. A 1968, 622, and references cited therein.
CI
\
233 pm
ph-2p'\
Ph
(la)
Ph'
(Ib)
Fig. 1. Schematic representation of the diastereomeric diphosphane complexes
( 1 a ) and ( I b ) .
[*] Doz. Dr. G. Huttner, Dip].-Chem. P. Friedrich, DipLChem. H. Willenberg, Dr. H.-D. Miiller
Anorganisch-chemisches Institut der Technischen Universitat
Arcisstrasse 21, D-8000 Miinchen 2 (Germany)
p * ] This work was supported by the Deutsche Forschungsgemeinschaft
and the Fonds der Chemischen Industrie.
260
A Monothiooxalato-0,s-oxo Complex of Molybdenum
Containing Two Sg- Ligands
By Karl Mennemann and Ruiner Mattesp]
During studies on the reactivity of mono- and dinuclear
halogeno- and oxalato-oxomolybdates(v) towards thiooxalated'] we isolated from aqueous solution dark red crystals
of a molybdenum compound having an unexpectedly high
sulfur content. The IR spectrum revealed the presence of
0,s-coordinated monothiooxalate['I and of terminal oxygen
[ v ( M o O ) :930cm-']; a band at 530cm-' could not initially
be assigned.
X-Ray structure analysis[31showed the molybdenum atom
to be heptacoordinated in the form of a pentagonal bipyramid
(cf. Fig. 1): the equatorial plane contains only sulfur atoms,
oiz. the S atom of the monothiooxalate ligand [d(MoS):
253(2)pm] and, surprisingly, two S2 groups with a mean MoS distance of 238(2)pm and an S-S distance of 203(2)pm; a terminal oxygen atom and an 0 atom belonging to the carboxyl
group of the monothiooxalate form the two apices of the
bipyramid [d(MoO): 170(4)and 231(4)pm]. Thus the geometry
[*] Prof. Dr. R. Mattes, Dipl.-Chem. K. Mennemann
Anorganisch-chemisches Institut der Universitat
Gievenbecker Weg 9, D-4400 Miinster (Germany)
Angew. Chem. Int. Ed. Engl. I6 (1977) NO. 4
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forma, bond, pentacarbonylchromium, structure, diastereoisomers, length, dichloro, analysis, bis, diastereomeric, diphenyldiphosphane, differing
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