COMMUNICATIONS
[10] 6: At room temperature, only an exchanged-broadened 31P NMR
signal is observed; the meso form 6 is the dominant diastereomer at
Experimental Section
low temperatures. M.p. 1868C; 31P NMR (CDCl
, � 608C): 6: d
3
3
: Methyl triflate (2, 5 g, 30.5 mmol) was added to a saturated solution of 1
485 mg, 0.88 mmol) in CH Cl . Evaporation of solvent and excess 2 led to
a yellow residue, which was dissolved in CH Cl . After addition of hexane,
precipitated as an analytically pure, microcrystalline powder, which was
isolated by filtration and dried under vacuum (442 mg, 0.62 mmol, yield:
0%). Crystals suitable for an X-ray structure analysis could be obtained
by layering a saturated solution of 3 in CH Cl with diethyl ether. After
min sufficiently large platelets appeared, which had to be removed at
once from the mother liquor to avoid decomposition. M.p. 1188C
�
32.4 (s); 6': d � 35.8 (s). The meso isomer 6 was also characterized
(
2
2
by X-ray structure analysis, and showed no special features (P�P:
2
2
2
1
3
.216(1) ; S8(P) 315.9): monoclinic, space group P2 /c; a
1
3
1.0304(4), b 19.3032(10), c 18.2587(8) , b 102.003(2)8; V
3
802.7(3) ; Z 4. Further details can be obtained from the authors.
7
[
[
[
11] M. Koenig, G. Etemand-Moghadam, C. Tachon, J. Bellan, Phosphorus
2
2
Sulfur 1987, 30, 425.
12] For a related study on p-bond energies in protonated Schiff bases, see
D. Bond, J. Am. Chem. Soc. 1991, 113, 385.
5
(
(
decomp.); UV/Vis: l 249.4 (p !p*, PP), 283.7 (p !p*, aryl), 364.2
13] a) For all structures, geometry and frequency calculations were
performed at the MP2(fc)/6-31G(d,p) level of theory using the
31
1
n !p*, PP); P NMR (CD
Cl
Cl
): d 237.0 (d, ArCH
P), 332.2 (d, JPP
2
2
3
1
6
33 Hz, ArP); H NMR (CD
2
2
): d 1.38 (s, 9H, p-tBu), 1.40 (s, 9H, p-
[
13b]
GAUSSIAN 94
program package. Refined energies were obtained
5
tBu), 1.55 (d, JPH 2.44 Hz, 18H, o-tBu), 1.60 (s, 18H, o-tBu), 1.86 (dd,
in CCSD(T)/6-311G(2d,2p) single point calculations on the MP2-
optimized structures. Calculated energetics were corrected for zero-
point vibrational energy (ZPE) using the unscaled MP2 values;
b) M. J. Frisch, G. W. Trucks, H. B. Schlegel, P. M. W. Gill, B. G.
Johnson, M. A. Robb, J. R. Cheeseman, T. Keith, G. A. Petersson,
J. A. Montgomery, K. Raghavachari, M. A. Al-Laham, V. G. Zakr-
zewski, J. V. Ortiz, J. B. Foresman, J. Cioslowski, B. B. Stefanov, A.
Nanayakkara, M. Challacombe, C. Y. Peng, P. Y. Ayala, W. Chen,
M. W. Wong, J. L. Andres, E. S. Replogle, R. Gomperts, R. L. Martin,
D. J. Fox, J. S. Binkley, D. J. Defrees, J. Baker, J. P. Stewart, M. Head-
Gordon, C. Gonzalez, J. A. Pople, Gaussian, Inc., Pittsburgh, PA,
2
3
4
5
J
PH 19.80, JPH 4.87 Hz, 3H, CH
3
), 7.66 (dd, JPH 1.83, JPH 1.83 Hz,
4
2
H, aryl-H), 7.70 (d, JPH 5.18 Hz, 2H, aryl-H).
Received: June 7, 1999 [Z13523IE]
German version: Angew. Chem. 1999, 111, 3546 ± 3548
Keywords: cations ´ dissociation energies ´ multiple bonds ´
nitrogen ´ phosphorus
1
995.
[
1] Review: a) H. Grützmacher, C. M. Marchand, Coord. Chem. Rev.
997, 163, 287; b) D. Ohlmann, C. M. Marchand, H. Grützmacher,
[14] H. Hamaguchi, M. Tasumi, M. Yoshifuji, N. Inamoto, J. Am. Chem.
Soc. 1984, 106, 508.
1
G. S. Chen, D. Framer, R. Glaser, A. Currao, R. Nesper, H. Pritzkow,
Angew. Chem. 1996, 108, 317; Angew. Chem. Int. Ed. Engl. 1996, 35,
[15] a) G. Trinquier, J.-P. Malrieu, J. Am. Chem. Soc. 1987, 109, 5303;
b) review: M. Driess, H. Grützmacher, Angew. Chem. 1996, 108, 900;
Angew. Chem. Int. Ed. Engl. 1996, 35, 828.
300; c) G. Frenking, S. Fau, C. M. Marchand, H. Grützmacher, J. Am.
Chem. Soc. 1997, 119, 6648.
[16] a) J. Niemann, W. W. Schoeller, V. von der Gönna, E. Niecke, Chem.
Ber. 1991, 124, 1563; b) M. Dietrich, J. Heinze, H. Fischer, F. A.
Neugebauer, Angew. Chem. 1986, 98, 999; Angew. Chem. Int. Ed.
Engl. 1986, 25, 1021.
[
[
2] a) H. Grützmacher, H. Pritzkow, Angew. Chem. 1991, 103, 721; Angew.
Chem. Int. Ed. Engl. 1991, 30, 709; b) U. Heim, H. Pritzkow, H.
Schönberg, H. Grützmacher, J. Chem. Soc. Chem. Commun. 1993,
674.
3] Reviews: a) A. H. Cowley, R. A. Kemp, Chem. Rev. 1985, 85, 367;
b) M. Sanchez, M.-R. Mazi eÁ res, L. Lamand e , R. Wolf in Multiple
Bonds and Low Coordination in Phosphorus Chemistry (Eds.: M.
Regitz, O. Scherer), Thieme, Stuttgart, 1990, p. 129.
[
4] This ion is an analogue of hydrazinium ions: a) L. M. Anderson, A. S.
Butler, A. S. McIntosh, J. Chem. Soc. Perkin Trans. 2 1987, 1239; b) S. F.
Nelsen, R. T. Landis II, J. Am. Chem. Soc. 1974, 96, 1788.
Polyoxometalates as Reduction Catalysts:
Deoxygenation and Hydrogenation of
Carbonyl Compounds**
[
5] A. H. Cowley, J. E. Kilduff, N. C. Norman, M. Pakulski, J. Chem. Soc.
Dalton Trans. 1986, 1801.
6] J. R. Bews, C. Glidewell, J. Organomet. Chem. 1983, 255, 49.
7] a) M. T. Nguyen, Chem. Phys. Lett. 1987, 135, 73; b) E. M. Cruz, X.
Lopez, M. Ayerbe, J. M. Ugalde, J. Phys. Chem. A 1997, 101, 2166.
8] M. Yoshifuji, I. Shima, N. Inamoto, J. Am. Chem. Soc. 1981, 103, 4597.
[
[
Vladimir Kogan, Zeev Aizenshtat, and
Ronny Neumann*
[
[
9] Crystal data for 3: monoclinic, space group P2
1
/m; a 11.5412(2), b
3
1
4.5829(3), c 12.6593(1) , b 107.69(1)8; V 2029.84(6) ; Z 2,
Investigations concerning the use of polyoxometalates as
catalysts in both liquid and gas-phase reactions have intensi-
fied significantly over the last decade. These catalytic
MoKa radiation, 2Vmax 41.68. Of 8822 reflections, 2248 were inde-
2
pendent (Rint. 0.0919); R
1
0.0654, wR
2
0.1855 (based on F ) for
259 parameters and 1539 reflections with I > 2s(I). The poorly
diffracting platelet was partially merohedrally twinned (twin law:
[1]
[2]
applications in acid catalysis and oxidation have taken
advantage of the strong Brùnsted acidity of heteropoly acids
and the inherent stability of the polyoxometalate framework
to oxidative degradation in the presence of strong oxidants
and at high temperatures. Although a few examples of
�
1 0 0 0 � 1 0 0 0 1, relationship of twin components: 0.7194:0.2806).
Nevertheless the structure could be solved by direct methods and was
2
refined against full matrix (versus F ) with SHELXTL (Version 5.0),
assigning the reflections listed in the hkl file to each twin component.
Owing to the poor data-to-parameter ratio non-hydrogen atoms were
refined with restricted anisotropic displacement parameters using
SIMU and ISOR instructions. One p-tBu group was refined isotropi-
cally as a rigid group disordered over two positions with relative
occupancy factors of 0.8 and 0.2. Hydrogen atoms were refined on
calculated positions using the riding model or as rigid groups.
Crystallographic data (excluding structure factors) for the structures
reported in this paper have been deposited with the Cambridge
Crystallographic Data Centre as supplementary publication no.
CCDC-120592. Copies of the data can be obtained free of charge on
application to CCDC, 12 Union Road, Cambridge CB21EZ, UK (fax:
[
*] Prof. Dr. R. Neumann, V. Kogan, Prof. Dr. Z. Aizenshtat
Casali Institute of Applied Chemistry
Graduate School of Applied Science
The Hebrew University of Jerusalem
Jerusalem, 91904 (Israel)
Fax : ( 972)2-6528250
E-mail: ronny@vms.huji.ac.il
[**] The Israel Electric Company is thanked for their generous support in
funding a fellowship for V.K.
(
44)1223-336-033; e-mail: deposit@ccdc.cam.ac.uk).
Angew. Chem. Int. Ed. 1999, 38, No. 22
ꢀ WILEY-VCH Verlag GmbH, D-69451 Weinheim, 1999
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