"Naked" phosphorus as a bent bridging ligand

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[5] a) C. Ollivier, P. Renaud, Chem. Eur. J. 1999, 5, 1468 ± 1473. For
related radical reactions involving organoboranes, see b) C. Ollivier,
R. Chuard, P. Renaud, Synlett 1999, 807 ± 809; c) N. Kihara, C.
Ollivier, P. Renaud, Org. Lett. 1999, 1, 1419 ± 1422.
[6] This work was presented at the 1999 meeting of the New Swiss,
Chemical Society (Basel, October 12, 1999); abstract: C. Ollivier, P.
Renaud, Chimia 1999, 53, 368.
[7] Recently, we have shown that the reaction of B-alkylcatecholboranes
with stable aminoxyl radicals such as 2,2,6,6-tetramethylpiperidine-N-
oxide (TEMPO) produces cleanly alkyl radicals, see ref. [5b].
[8] It is well established that alkylboranes react efficiently with hetero-
atom-centered radicals such as alkoxyl radicals. For review articles,
see H. C. Brown, M. M. Midland, Angew. Chem. 1972, 84, 702 ± 710;
Angew. Chem. Int. Ed. Engl. 1972, 11, 692; A. Ghosez, B. Giese, H.
Zipse in Methoden der Organischen Chemie (Houben-Weyl) 4th ed.
1952 ± , Vol. E19a, 1989, pp. 753 ± 765. Reaction with carbon radicals
has not been observed except for a recently reported intramolecular
reaction: R. A. Batey, D. V. Smil, Angew. Chem. 1999, 111, 1912 ±
1915; Angew. Chem. Int. Ed. 1999, 38, 1798 ± 1800.
removed or transformed into a variety of functional groups as
amply demonstrated by Barton.[13] Since radical precursors
are generated through a hydroboration step, this procedure
could take advantage of the chemo- and regioselectivity of the
hydroboration and offers a very simple and efficient method
for the preparation of highly functionalized systems through
inter- and intramolecular radical addition. Applications of this
approach to cascade reactions starting from a polyene are
currently under investigation. Finally, preparation of optically
active materials through enantioselective hydroboration of
prochiral alkenes should represent valuable entries into the
synthesis of enantiomerically enriched compounds.
Experimental Section
Sulfur inclusion into B-Alkylcatecholboranes: Catecholborane (0.64 mL,
6.0 mmol) was added dropwise at 08C to a solution of the olefin (3.0 mmol)
and N,N-dimethylacetamide (28.0 mL, 0.3 mmol) in CH2Cl2 (2.0 mL). The
mixture was heated under reflux for 3 h. Methanol (0.15 mL, 3.6 mmol) was
added at 08C and the mixture was stirred for 15 min at room temperature.
Â
[9] M. Newcomb, M. U. Kumar, J. Boivin, E. Crepon, S. Z. Zard,
Tetrahedron Lett. 1991, 32, 45 ± 48; A. L. J. Beckwith, I. G. E. Davison,
Tetrahedron Lett. 1991, 32, 49 ± 52.
[10] A. L. J. Beckwith, B. P. Hay, J. Am. Chem. Soc. 1988, 110, 4415 ± 4416;
A. L. J. Beckwith, B. P. Hay, J. Am. Chem. Soc. 1989, 111, 230 ± 234.
[11] C. E. Garrett, G. C. Fu, J. Org. Chem. 1996, 61, 3224 ± 3225.
[12] B. Giese, W. Damm, F. Wetterich, H.-G. Zeitz, Tetrahedron Lett. 1992,
33, 1863 ± 1866.
[13] D. H. R. Barton, C. Y. Chern, J. C. Jaszberenyi, Aust. J. Chem. 1995,
48, 407 ± 425, and references therein.
[14] Evaporation of CH2Cl2 afforded better results with tertiary radicals.
With secondary and primary alkyl radicals, similar yields are obtained
without evaporating the solvent. This evaporation step was not
employed when running conjugate additions.
The CH2Cl2 was evaporated under vacuum with strict exclusion of O2.[14]
A
yellow solution of PTOC-OMe (9.0 mmol), freshly prepared by stirring for
1 h in the dark the sodium salt of N-hydroxypyridine-2-thione (1.41 g,
9.45 mmol) and methyl chloroformate (0.7 mL, 9.0 mmol) in benzene
(15 mL), was added to the B-alkylcatecholborane followed by 1,3-dimethyl
hexahydro-2-pyrimidone (DMPU; 0.36 mL, 3.0 mmol). The reaction
mixture was irradiated at 108C with a 150 W tungsten lamp for about
14 h, and treated with 1n NaOH (20 mL). The aqueous layer was extracted
with CH2Cl2 and the combined organic phases were washed with a
saturated NaCl solution (30 mL), dried with MgSO4, and concentrated in
vacuo. The crude product was purified by flash chromatography (hexane/
EtOAc).
Conjugate addition: Catecholborane (0.64 mL, 6.0 mmol) was added
dropwise at 08C to
a solution of the olefin (3.0 mmol) and N,N-
dimethylacetamide (28.0 mL, 0.3 mmol) in CH2Cl2 (2.0 mL). The reaction
mixture was heated under reflux for 3 h. Methanol (0.15 mL, 3.6 mmol) was
added at 08C and the mixture was stirred for 15 min at room temperature.
ªNakedº Phosphorus as a Bent Bridging
Ligand**
A
yellow solution of PTOC-OMe (9.0 mmol), freshly prepared as
Peter Kramkowski and Manfred Scheer*
previously described, was added to the B-alkylcatecholborane followed
by the activated alkene (15 mmol) in benzene (15 mL) and DMPU
(0.36 mL, 3.0 mmol). In the case of dimethyl fumarate as the alkene,
CH2Cl2 (15 mL) was used instead of benzene. The reaction mixture was
irradiated at 108C with a 150 W tungsten lamp for about 14 h, and treated
with 1n NaOH (20 mL). The aqueous layer was extracted with CH2Cl2 and
the combined organic phases were washed with a saturated NaCl solution
(30 mL), dried with MgSO4, and concentrated in vacuo. The crude product
was purified by flash chromatography (hexane/EtOAc).
Dedicated to Professor Dirk Walther
on the occasion of his 60th birthday
Only a small number of the complexes containing pnico-
genido (E3 ) ligands of the heavier Group 15 elements (E ˆ P,
As, Sb, Bi)[1] are known in which the ligands display low
coordination numbers 1 and 2. Only in 1995 were the first
complexes of type A,[6] with terminal ligands and coordina-
tion number 1, synthesized and structurally characterized
Received: September 20, 1999 [Z14034]
[1] a) B. Giese, Radicals in Organic Synthesis: Formation of Carbon
Carbon Bonds, Pergamon, Oxford, 1988; b) D. P. Curran in Compre-
hensive Organic Synthesis, Vol. 4 (Eds.: B. M. Trost, I. Fleming),
Pergamon, Oxford, 1991, pp. 715 ± 777; c) W. B. Motherwell, D. Crich,
Free Radical Chain Reactions in Organic Synthesis, Academic Press,
London, 1992; d) D. P. Curran, N. A. Porter, B. Giese, Stereochemistry
of Radical Reactions, VCH, Weinheim, 1996; e) J. Fossey, D. Lefort, J.
Sorba, Free Radicals in Organic Synthesis, Wiley, Chichester, 1995;
f) C. Chatgilialoglu, P. Renaud in General Aspects of the Chemistry of
Radicals (Ed.: Z. B. Alfassi), Wiley, Chichester, 1999, pp. 501 ± 538.
[2] a) G. Stork, N. H. Baine, J. Am. Chem. Soc. 1982, 104, 2321 ± 2323;
b) S. D. Burke, W. F. Fobare, D. A. Armistead, J. Org. Chem. 1982, 47,
3348 ± 3350; c) B. Giese, J. Dupuis, Angew. Chem. 1983, 95, 633 ± 634;
Angew. Chem. Int. Ed. Engl. 1983, 23, 622 ± 623. For review articles,
see ref. [1a] and d) B. Giese, Angew. Chem. 1983, 95, 771 ± 782; Angew.
Chem. Int. Ed. Engl. 1983, 23, 753 ± 764.
ꢀ
with the compounds [(Ar'RN)3Mo P] (Ar' ˆ 3,5-C6H3Me2,
R ˆ C(CD3)2CH3)[2]
and
[(ꢁN3Nꢂ)M E]
[ꢁN3Nꢂ ˆ
ꢀ
N(CH2CH2NSiMe3)3; E ˆ P, M ˆ W, Mo;[3] E ˆ As, M ˆ W,[4]
Mo[5]]. We recently found the asymmetric linear coordination
mode B with coordination number 2 in the complexes
[(ꢁN3Nꢂ)M E !MLm] (MLm ˆ GaCl3;[7] M(CO)4, M ˆ Cr,
ꢀ
W ] and [(RO)3W P !M(CO)5] (M ˆ Cr, W; R ˆ tBu[8], Ar
[5]
ꢀ
(2,6-Me2C6H3)[9]). Symmetrical linearly bridged complexes of
[*] Prof. Dr. M. Scheer, Dr. P. Kramkowski
Institut für Anorganische Chemie der Universität
76128 Karlsruhe (Germany)
Fax : (‡ 49)721-661921
E-mail: mascheer@achibm6.chemie.uni-karlsruhe.de
[3] P. A. Baguley, J. C. Walton, Angew. Chem. 1998, 110, 3272 ± 3283;
Angew. Chem. Int. Ed. 1998, 37, 3072 ± 3082.
[4] H. C. Brown, E. Negishi, J. Am. Chem. Soc. 1971, 93, 3777 ± 3779.
[**] This work was supported by the Deutsche Forschungsgemeinschaft
and the Fonds der Chemischen Industrie.
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Angew. Chem. Int. Ed. 2000, 39, No. 5

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type C of the heavier Group 15 elements are so far exclusively
known for cationic complexes, which were prepared by
Huttner and co-workers.[10] Neutral compounds of this type
are only known for E ˆ P in the complexes [{Cp2Zr}2(m-P)]
and [{(R'RN)3Mo}2(m-P)] (R ˆ Ph; R' ˆ tBu), synthesized in
the groups of Stephan[11] and Cummins[12], respectively. We
recently synthesized the first neutral example for antimony
ˆ
ˆ
in the complex [(ꢁN3Nꢂ)W Sb W(ꢁN3Nꢂ)] (C) [ꢁN3Nꢂ ˆ
N(CH2CH2NCH2tBu)3].[13] The nonlinear bent bridging coor-
dination mode D of the coordination number 2, however, has
not yet been observed for the heavier Group 15 elements.[1] So
far this coordination mode has been found exclusively for
nitrogen,[14] for example, in complexes of vanadium[15] and
tantalum[16]. We report here the synthesis, structure, and
properties of the first complex with a bent bridging phospho-
rus ligand of coordination number 2.
The formation of 3 could occur by the dimerization of two
ꢀ
phosphido complex units [(ArO)3W P] with simultaneous
addition of a further phosphaalkyne. This intermediate is
stabilized by 1,3-ArO shifts from the Watoms to the P atom of
the additionally attached phosphaalkyne with formation of a
tungsten ± tungsten bond. The postulated dimerization of two
ꢀ
[(ArO)3W P] intermediates is also observed for the isolable
ꢀ
phosphido complex [(ArO)3W P !W(CO)5], leading to the
planar four-membered ring de-
rivative 4.[9]
In our studies on the synthesis of phosphido complexes of
ꢀ
type B with the formula [thf(ArO)3W P !M(CO)5] using the
The molecular structure of
3[19] (Figure 1) reveals a four-
membered ring of the atoms
W1, P1, W2, and P2, which is
folded along the W1 ± W2 bond
(2.8162(8) Š) (dihedral angle:
151.48) and further coordinated
by a tBuCP unit (C1 and P3). The atom C1 is connected to the
tungsten atom W2 and to the phosphorus atoms P1 and P3
three-component reaction between [W2(OAr)6] (Arˆ 2,6-
Me2C6H3)[17] and R'C P (R' ˆ tBu, Mes; Mes ˆ 2,4,6-
ꢀ
Me3C6H2) in the presence of [M(CO)5thf] (M ˆ Cr, W),[9] we
have also investigated the corresponding two-component
[18]
ꢀ
ꢀ
systems [W2(OAr)6]/R'C P.
Whereas, for MesC P only
the four-membered ring derivatives 1a and 2a were obtained
as a consequence of the reaction of the initially formed
phosphido complex and alkylidyne complex, respectively,
with further phosphaalkyne and subsequent 1,3-OAr shift
ꢀ
(Scheme 1), in the case of tBuC P the complex 3 of type D
Scheme 1.
Figure 1. Molecular structure of 3 (hydrogen atoms are omitted for
clarity). Selected bond lengths [Š] and angles [8]: W1-P2 2.301(2), W2-P2
2.284(2), W1-P1 2.483(2), W2-P1 2.483(2), W1-P3 2.475(2), W1-W2
2.8162(8), W2-C1 2.200(7), P1-C1 1.860(7), P3-C1 1.743(6); W1-P2-W2
75.78(6), W1-P1-W2 70.22(5), W1-P3-C1 95.1(2), P1-W1-P2 100.98(7), P1-
W2-P2 103.68(7), C1-P1-W2 60.4(2), C1-P1-W1 91.9(2), P3-C1-W2 99.0(3).
with a bent phosphorus ligand [Eq. (1)] is obtained in addition
to the cyclic complexes 1b and 2b. The dark red crystalline
complex 3 is extremely sensitive towards hydrolysis and is
readily soluble in n-pentane, toluene, and THF. The molecular
ion peak is observed in the mass spectrum of 3.
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through single bonds. The lone pair of electrons on the
phosphorus atom P3 coordinates to the W1 atom, as indicated
by the P ± W distance of 2.475(2) Š. The predominant
structural feature of 3 is the substituent-free phosphorus
atom P2 that bridges the atoms W1 and W2. The bond lengths
of the phosphorus atom P2 to the atoms W1 and W2 are
2.301(2) and 2.284(2) Š, respectively, with an angle W1-P2-
W2 of 75.78(6)8. Comparison with the structural data for the
complex 4, in which the symmetrical phosphido ligand has the
coordination number 3 (d(W P) 2.2805(17) and 2.2806(17) Š;
a(W-P-W) 76.69(7)8), demonstrates the insignificant struc-
tural influence of the additional coordination of the phosphi-
do phosphorus atom to the W(CO)5 moiety in 4. Presumably
the planar geometry in 4 is responsible for a shortening of the
W P bonds. The differently substituted and therefore elec-
tronically different W atoms could be the reason for the
asymmetrical phosphido bridge of the P2 atom in 3.
The 1H-coupled as well as the 1H-decoupled 31P NMR
spectra of 3 show three singlets. The signal at d ˆ 831.8 can be
assigned to the naked phosphorus atom P2. In comparison
with the P atom coordinating to a W(CO)5 moiety in 4, the
signal appears shifted down field by almost 300 ppm (4: d ˆ
558.2). A similar difference in the chemical shifts, combined
with a high-field shift in the case of additional coordination of
the P atom is observed for the phosphido complexes
(5b), respectively, appears on this signal, which has to be
assigned to the coupling with the tungsten atoms of the
W(OAr)2 moieties. No couplings to the W(OR)2 groups were
found, either in complex 4[9] with the coordination number 3
on the phosphido phosphorus atom or in its tBu-substituted
analogues.[8] This highlights the different geometry at the
tungsten alkoxide groups of 5 in comparison with those of 3
and 4, respectively. All other chemical shifts of the phospho-
rus atoms in 5a, b are slightly different from those in 3 (a
down field shift of 10 ± 12 ppm in each case).
The cause of the so far unique formation of the bent bridged
P1 ligand of 3 is the predominant tendency of the phosphorus
atom to incorporate its lone pair of electrons into the bonding
mode to form either the coordination number 3 or the linear
coordination modes B or C. Thus, in the complex 3 optimum
conditions for the realization of this coordination mode D are
present: 1) the high tendency of (RO)3W fragments to
eliminate RO groups under formation of a W W bond[9]
and 2) optimal steric parameters of the substituents at the
tungsten alkoxide and on the phosphaalkyne, which prevent a
subsequent reaction with the alkoxide dimer to form
[{(RO)3W}3(m3-P)] (R ˆ 2,6-Me2C6H3), as we had observed
for R ˆ neopentyl.[8] Furthermore, the reaction procedure is
also very important; long reaction times at very low temper-
ꢀ
atures give the metathesis product [(ArO)3W P] the possi-
ꢀ
ꢀ
ꢀ
[(tBuO)3W P] (d ˆ 845.0) and [(tBuO)3W P !W(CO)5]
(d ˆ 546.0).[8] Furthermore, as a result of the two ArO
substituents, the signal of the phosphorus atom P3 in 3 is
detected at high field (d ˆ 97.5). However, this effect is less
distinct than with the P atoms bearing single ArO substituents
in the WC2P and WCP2 four-membered ring complexes 1b
(d ˆ 151.5) and 2b (d ˆ 87.1), respectively. Only the signal
of the phosphorus atom P3 shows coupling to tungsten
(1J(W,P) ˆ 216 Hz). No coupling to the tungsten atoms was
observed for either of the other singlets, including that of
atom P1 at 140.4 ppm.
bility to react with a second molecule and tBuC P simulta-
neously to give the complex 3. The exclusive reaction of the
ꢀ
phosphido complex with tBuC P leads to complex 2b.
Therefore, the accessibility of complexes of type D for the
heavier homologues of phosphorus seems to be only possible
after the first synthesis of the corresponding arsa- and
stibaalkynes.
Experimental Section
1a and 2a: [W2(OAr)6][20] (Arˆ 2,6-Me2C6H3) (550 mg, 0.5 mmol) was
The bent bridged phosphorus atom P2 in 3 should be able to
coordinate through its lone pair of electrons to Lewis acid
complex fragments such as [M(CO)5thf]. Thus, 3 reacts with
[M(CO)5thf] (M ˆ W, Cr) to give the complexes 5a, b
[Eq. (2)]. The signals of 3 could no longer be observed in
the 31P NMR spectrum of the crude mixture of reaction (2).
dissolved in toluene (25 mL) and frozen with liquid nitrogen. A solution of
[21]
ꢀ
MesC P (Mes ˆ 2,4,6-Me3C6H2) (162 mg, 1 mmol) in n-hexane (20 mL)
was added at 788C. The reaction mixture was allowed to warm to room
temperature over a period of 15 h. All volatile materials were then
removed under high vacuum. The reddish brown residue was characterized
by 31P{1H} NMR spectroscopy, which revealed the presence of 1a and 2a.
No separation of 1a and 2a was achieved either by fractional crystallization
or by column chromatographic work-up on silica gel and Al2O3, respec-
tively. 31P{1H} NMR (101.256 MHz, [D6]benzene, 298 K, 85% H3PO4 ext.):
1
1
1a: d ˆ 154.8 (s); 2a: d ˆ 434.2 (d, J(P,P) ˆ 442 Hz), 89.5 (d, J(P,P) ˆ
442 Hz).
3: [W2(OAr)6] (Arˆ 2,6-Me2C6H3) (550 mg, 0.5 mmol) was dissolved in
THF (15 mL) and cooled to 608C. To this solution was added a solution
of tBuC P[22] (100 mg, 1 mmol) in n-pentane (15 mL) over 3 h. The reaction
ꢀ
mixture was allowed to warm to room temperature over a period of 15 h.
After removal of the solvent, the residue was extracted with n-pentane
(30 mL) and filtered through celite. After the volume of solvent had been
reduced to about 10 mL, dark red crystals of 3 (75 mg, 12%) were obtained.
The solid reaction residue was dissolved in toluene (30 mL) and filtered
through celite. Fractional crystallization failed to separate the four-
membered ring derivatives 1b and 2b. 31P{1H} NMR (101.256 MHz,
[D6]benzene, 298 K, 85% H3PO4 ext.): 1b: d ˆ 151.5 (s); 2b: d ˆ 446.0
The 31P NMR data of 5a, b support the coordination of the
bridging atom P2 to the corresponding M(CO)5 group (M ˆ
Cr, W) with a significant high field shift of 180 ppm (M ˆ W:
650.5 ppm) and 115 ppm (M ˆ Cr: 715.0 ppm), respectively,
for the resonance signal of this phosphorus atom. A pair of
satellites with a coupling constant of 210 Hz (5a) and 197 Hz
(d, 1J(P,P) ˆ 449 Hz),
87.1 (d, 1J(P,P) ˆ 449 Hz). 3: 31P{1H} NMR
(101.256 MHz, [D6]benzene, 298 K, 85% H3PO4 ext., PA ˆ P2, PB ˆ P1,
PC ˆ P3): d ˆ 831.8 (PA: s), 140.4 (PB: s), 97.5 (PC: s; 1J(W,P) ˆ 216 Hz);
1H NMR [250.113 MHz, [D6] benzene, 298 K, TMS): d ˆ 6.58 ± 7.16 (18H,
aromatic protons) 2.50 (12H, Me), 2.05 (12H, Me), 1.36 (9H, tBu); EI-MS
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‡
‡
(70 eV; 1408C): m/z (%): 1256 (1) [M ], 1014 (4) [M
2OAr], 772 (10)
solution of
[15] T. S. Haddad, A. Aistars, J. W. Ziller, M. N. Doherty, Organometallics
1993, 12, 2420 ± 2422.
‡
[M
4OAr].
[16] a) H. Plenio, H. W. Roesky, M. Noltemeyer, G. M. Sheldrick, Angew.
Chem. 1988, 100, 1377 ± 1378; Angew. Chem. Int. Ed. Engl. 1988, 27,
1330; b) M. M. B. Holl, M. Kersting, B. D. Pendley, P. T. Wolczanski,
Inorg. Chem. 1990, 29, 1518 ± 1526.
5a, b: Complex
3
(50 mg, 0.04 mmol) was added to a
[M(CO)5thf] (0.06 mmol; M ˆ W, Cr) in THF (25 mL) and stirred for
24 h at room temperature. Then all of the volatiles were removed under
high vacuum and the residue was recrystallized from toluene to give the
dark red complexes 5a (45 mg; 71%) and 5b (35 mg; 60%), respectively.
31P{1H} NMR (101.256 MHz, [D6]benzene, 298 K, 85% H3PO4 ext.): 5a
(M ˆ W): d ˆ 650.5 (s, 1J(W,P) ˆ 210 Hz), 152.8 (s), 107.2, (s, 1J(W,P) ˆ
233 Hz); 5b (M ˆ Cr): d ˆ 715.0 (s, 1J(W,P) ˆ 197 Hz), 153.7 (s), 108.0 (s,
1J(W,P) ˆ 233 Hz).
[17] The single-crystal X-ray analysis of [(ArO)6W2][19] (Arˆ 2,6-
Me2C6H3) reveals a staggered orientation of the ArO ligands with a
ꢀ
very short W W triple bond of 2.3128(6) Š. This bond length is
shorter than that in the only crystallographically characterized dimeric
tungsten alkoxide complex [(CyO)6W2] (2.340(1) Š) without bridging
ligands; compare: M. H. Chisholm, K. Folting, M. Hampden-Smith,
C. A. Smith, Polyhedron 1987, 6, 1746 ± 1755.
Received: September 30, 1999 [Z14082]
ꢀ
[18] First investigations on such metathesis reactions between tBuC P and
[1] reviews: M. Scheer, E. Herrmann, Z. Chem. 1990, 30, 41 ± 55; O. J.
Scherer, Angew. Chem. 1990, 102, 1137 ± 1155; Angew. Chem. Int. Ed.
Engl. 1990, 29, 1104 ± 1122; O. J. Scherer, Acc. Chem. Res. 1999, 32,
751 ± 762; K. H. Whitmire, Adv. Organomet. Chem. 1998, 42, 1 ± 145.
[2] C. E. Laplaza, W. M. Davis, C. C. Cummins, Angew. Chem. 1995, 107,
2181 ± 2183; Angew. Chem. Int. Ed. Engl. 1995, 34, 2042 ± 2043.
[3] N. C. Zanetti, R. R. Schrock, W. M. Davis, Angew. Chem. 1995, 107,
2184 ± 2186; Angew. Chem. Int. Ed. Engl. 1995, 34, 2044 ± 2046.
[4] M. Scheer, J. Müller, M. Häser, Angew. Chem. 1996, 108, 2637 ± 2641;
Angew. Chem. Int. Ed. Engl. 1996, 35, 2492 ± 2496.
[5] N. C. Zanetti, R. R. Schrock, W. M. Davis, K. Wanninger, S. W. Seidel,
M. B. OꢂDonoghue, J. Am. Chem. Soc. 1997, 119, 11037 ± 11048.
[6] Reviews: M. Scheer, Angew. Chem. 1995, 107, 2151 ± 2153; Angew.
Chem. Int. Ed. Engl. 1995, 34, 1997 ± 1999; M. Scheer, Coord. Chem.
Rev. 1997, 163, 271 ± 286.
[7] M. Scheer, J. Müller, G. Baum, M. Häser, Chem. Commun. 1998,
1051 ± 1052.
[8] M. Scheer, P. Kramkowski, K. Schuster, Organometallics 1999, 18,
2874 ± 2883.
[9] P. Kramkowski, G. Baum, U. Radius, M. Kaupp, M. Scheer, Chem.
Eur. J. 1999, 5, 2890 ± 2898.
[10] a) A. Strube, G. Huttner, L. Zsolnai, Angew. Chem. 1988, 100, 1586 ±
1587; Angew. Chem. Int. Ed. Engl. 1988, 27, 1529; b) A. Strube, J.
Heuser, G. Huttner, H. Lang, J. Organomet. Chem. 1988, 356, C9-C11;
c) A. Strube, G. Huttner, L. Zsolnai, J. Organomet. Chem. 1990, 399,
267 ± 279; d) F. Bringewski, G. Huttner, W. Imhof, J. Organomet.
Chem. 1993, 448, C3-C5; e) S. J. Davies, N. A. Compton, G. Huttner,
L. Zolnai, S. E. Garner, Chem. Ber. 1991, 124, 2731 ± 2738.
[11] M. C. Fermin, J. Ho, D. W. Stephan, Organometallics 1995, 14, 4247 ±
4256.
[(tBuO)6W2] were carried out by G. Becker et al.: a) G. Becker, W.
Becker, R. Knebl, H. Schmidt, U. Weber, M. Westerhausen, Nova
Acta Leopold. 1985, 59, 55 ± 67; b) P. Binger in Multiple Bonds and
Low Coordination in Phosphorus Chemistry (Eds.: M. Regitz, O. J.
Scherer), Thieme, Stuttgart 1990, p. 100.
[19] Crystal structure analyses of 3 ´ 0.5C5H12 and [(ArO)6W2]. STOE
IPDS area-detector diffractometer with MoKa radiation (l ˆ
0.71073 Š). The structures were solved by direct methods using
SHELXS-86,[23a] and refined by full-matrix least-squares on F 2 using
SHELXL-93[23b], with anisotropic displacement for non-H atoms.
Hydrogen atoms were placed in idealized positions and refined
isotropically using
a riding model. 3 ´ 0.5C5H12: C53H63O6P3W2 ´
0.5C5H12, Mr ˆ 1292.72, crystal size 0.11  0.08  0.04 mm, triclinic,
Å
space group P1 (no. 2); a ˆ 13.077(3), b ˆ 13.777(3), c ˆ 18.069(4) Š,
a ˆ 86.55(3), b ˆ 83.35(3), g ˆ 64.56(3)8, Tˆ 200(2) K, Z ˆ 2, Vˆ
2919.6(10) Š3, 1calcd ˆ 1.470 Mgm 3, m(MoKa) ˆ 40.63 cm 1, 10490 in-
dependent reflections (2qmax ˆ 528) of which 7715 observed with Fo ˆ
4s(Fo); 614 parameters, R1 ˆ 0.0381, wR2 ˆ 0.1050; [(ArO)6W2]:
C48H54O6W2, Mr ˆ 1094.62, crystal size 0.15  0.15  0.02 mm, mono-
clinic, space group P21/n (no. 14); a ˆ 11.830(2), b ˆ 9.935(2), c ˆ
18.193(4) Š, b ˆ 90.85(3)8, Tˆ 183(1) K, Z ˆ 2, Vˆ 2138.0(7) Š3,
1calcd ˆ 1.700 Mgm 3, m(MoKa) ˆ 54.24 cm 1, 3935 independent reflec-
tions (2qmax ˆ 538), 3360 of which observed with Fo ˆ 4s(Fo); 259
parameters, R1 ˆ 0.0384, wR2 ˆ 0.1090. Crystallographic data (exclud-
ing structure factors) for the structures reported in this paper have
been deposited with the Cambridge Crystallographic Data Centre as
supplementary publication no. CCDC-135166 (3 ´ 0.5C5H12) and
CCDC-135167 ([(ArO)6W2]). Copies of the data can be obtained
free of charge on application to CCDC, 12 Union Road, Cambridge
CB21EZ, UK (fax: (‡44)1223-336-033; e-mail: deposit@ccdc.cam.
ac.uk).
[12] M. J. A. Johnson, P. M. Lee, A. L. Odom, W. M. Davis, C. C.
Cummins, Angew. Chem. 1997, 109, 110 ± 113; Angew. Chem. Int.
Ed. Engl. 1997, 36, 87 ± 91.
[20] I. A. Latham, L. R. Sita, R. R. Schrock, Organometallics 1986, 5,
1508 ± 1510.
[13] M. Scheer, J. Müller, Chem. Commun. 1998, 2505 ± 2506.
[14] Reviews: a) K. Dehnicke, J. Strähle, Angew. Chem. 1981, 93, 451 ± 464;
Angew. Chem. Int. Ed. Engl. 1981, 20, 413; b) K. Dehnicke, J. Strähle,
Angew. Chem. 1992, 104, 978 ± 1000; Angew. Chem. Int. Ed. Engl.
1992, 32, 955; c) W. A. Herrmann, Angew. Chem. 1986, 98, 57 ± 77;
Angew. Chem. Int. Ed. Engl. 1986, 25, 56.
[21] A. Mack, E. Pierron, T. Alspach, U. Bergsträsser, M. Regitz, Synthesis
1998, 1305 ± 1313.
[22] T. Allspach, M. Regitz, G. Becker, W. Becker, Synthesis 1986,
31 ± 36.
[23] a) G. M. Sheldrick, SHELXS-86, Universität Göttingen, 1986;
b) G. M. Sheldrick, SHELXL-93, Universität Göttingen, 1993.
Angew. Chem. Int. Ed. 2000, 39, No. 5
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