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Carbene Osmium Complexes by Double Metalation of Alkoxylalkyl- and Aminoalkylphosphanes.

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[61 The new cornponds 2,4,7, and 9 were fully characterized by spectroscopic
methods (IR, UV, 'H NMR, ,C NMR, MS) and by elemental analysis.
All the NMR signals of 2 were assigned from 2D NMR spectra (H,HCOSY. C,H-COSY. COLOC); NMR data were obtained for 6 (for selected
data see Experimental Procedure).
[7] a) H. D. Empsall, P. N. heys, B. L. Shaw, .lChem. Sac. Dalton Trans.
1978, 257-262 (Iodolysis of aryllithium compound); b) R. C. Larock,
L. W. Harrison. J. Am. Chem. SOC.1984, 106,42118-4227.
[XI G. Bringmann, H. Reuscher, Tetrahedron Left. 1989, 30, 5249-5252.
[9] Our own findings prove that I-iodo-2,6-dimethoxybenzenereacts in the
presence of styrene to form 2,6-dirnethoxystilbenein 91 % yield as product
of the Heck reaction and is therefore certainly not inert under the reaction
[lo] A. D. Ryabov, Chem. Rev. 1990, 90, 403-424.
[Ill A . J. Canty, Acc. Chem. Res. 1992, 2S, 83-90.
spectra of both compounds, 3 a and 3b, reveal a signal in the
low-field region which is split due to P-H coupling into a
doublet at 6 = 15.50 and 15.46, respectively, thus indicating
the presence of a =CHOR unit.[2c*61In the I3CNMR
spectrum of 3b a signal at 6 = 247.33 characteristic of a
carbene moiety appears in a position very similar to that of
cyclic oxycarbene complexes with the structural unit
OS=CCH,CH,CH(R)O.[~~The 31PNMR spectra of both
3 a and 3b show two doublets with a small P-P coupling
which confirms the cis position of the two phosphorus
atoms. These and other selected spectroscopic data for the
new compounds are summarized in Table 1.
Table 1. Selected spectroscopic data (without 'H and 13CNMR data for the
CH, and iPr groups). 'HNMR spectra at 400 MHz (at 60 MHz for 3 a only),
' T N M R spectra at 100.6 MHz (at 22.5 MHz for 10 only), "PNMR spectra
at 162.0 MHz for 3 b and 5, at 36.2 MHz for 3a, 8, 9, and 10.
Carbene Osmium Complexes by Double Metalation
of Alkoxylalkyl- and Aminoalkylphosphanes""
By Helmut Werner,* Birgit Weber, Oliver Niirnberg,
and Justin Wolf
Dedicated to Professor Ekkehard Winterfeldt
on the occasion of this 60th birthday
Since the first synthesis of a carbene metal complex by
Fischer and Maasbol,['l a wide variety of substrates have
been employed to generate metal-bound carbenes.[21In the
extensive literature, however, there is no single report to date
which illustrates that a compound of the general composition [L,M=CHX] (X = OR, NR,, etc.) is formed from a
suitable precursor CH,X and a transition metal compound.
We report herec3' that such a conversion succeeds with high
efficiency with osmium as the metal center if the CH,O or
CH,N group to be metalated is part of an alkoxylalkyl- or
aminoalkylphosphane molecule.
Recently, we described that [RuCI,(PPh,),] reacts with
alkoxyalkylphosphane 1by ligand exchange to give the octahedral complex [ R ~ C l ~ ( q ' - l )If
~ ]the
. osmium complex
treated with 1 under similar conditions (benzene, 80 "C,
45 h), a small amount of a yellow solid is isolated with a
composition corresponding to 3 a [Eq. (a)]. Because of the
3 a : 'HNMR (CDCI,): 6 =15.50 (d, J(PH) = 4.0 Hz, Os=CH), 3.80 (s,
OCH,); "PNMR (CDCI,): 6 = 15.37 and -19.00 (both d, J(PP) = 10.3 Hz)
3b: 'HNMR(C6Ds): 6 =15.46(d,J(PH) = 3.6Hz.Os=CH), 3.79 (s,OCH,);
' T N M R (CDCI,): 6 = 247.33 (t. J(PC) = 17.05 Hz, OS=C), 59.80 (s, OCH,);
"PNMR (CDCI,): 6 = 20.95 (d, J(PP) =10.1, J('870s3'P) = 266 Hz),
-15.13 (d, J(PP) =10.1, J('*'Os3'P) = 228 Hz)
5: ' H N M R (CDCI,): 6 =13.14 (d, J(PH) = 4.2 Hz, Os=CH), 3.23, 2.80, and
2.40 (each s, NCH,); ',CNMR (CDCI,): 6 = 212.99 (d, J(PC) =7.6 Hz,
Os=C), 50.59 and 49.69 (both s, NCH,); ,'PNMR (CDCI,): 6 =16.33 (d,
J(PP) =7.3, J('870s3'P) = 280Hz), -18.95 (d, J(PP) =7.3, J(1870s3iP)=
274 Hz)
8: 'HNMR (CGD,): 6 = 3.41 (s, OCH,); "CNMR (C,D,): 6 =185.25 (s,
CO,Me), 55.03 (s, OCH,); ,'PNMR (C,D,): 6 = 2.75(s)
9: IR (KBr): C[cm-'] =1915 (OsCO), 1710 (CO,Me, free), 1615 (CO,Me,
coord.); ' H N M R ([D,]toluene): d = 3.53 and 3.52 (both s, OCH,); "PNMR
(CDCI,): 6 = 24.80 and 9.59 (both d, J(PP) = 290.2 Hz)
10: 'HNMR ([D,]toluene, 60°C): 6 =7.38 and 6.95 (both m, C,H,),
3.52 (S, OCH,), 2.64 (t. J(PH) = 5.9 Hz, Os=CHF'h); ' T N M R (C,D,):
6 = 297.11 (t, J(PC) = 22.0 Hz, Os=C=CHPh), 109.31 (t. J(PC) = 6.1 Hz,
Os=C=CHPh), 53.25 (s, OCH,); ,'PNMR ([DJtoluene): 6 = 2.56(s) at
40°C; 6 = 9.51 and -2.93 (both d, J(PP) = 332 Hz) at -80°C.
The stereochemistry of 3b is established by the X-ray
structure analysis.['' It confirms (Fig. 1) that one of the
alkoxyalkylphosphane ligands is converted by double metalation of the methoxy group into a carbene unit, which is
1 = iPr,PCH,CH,OMe
unsatisfactory yield of 3 a (16 YO),we attempted to prepare
this complex directly from OsCI, . 3 H,O and 1. This reaction provided almost quantitatively (80YOyield with regard
to OsCI, . 3 H,O) a lemon-yellow crystalline product 3 b with
the same analytical composition as 3 a [Eq. (b)]. The 'HNMR
2 d
[ o s c I ~ ( = c H o c H ~ c H ~ P ~ P ~ ~ ) ( ~Ib)
[*I Prof. Dr. H. Werner, Dip].-Chem. B. Weber, Dip].-Chem. 0. Nurnberg,
Dr. J. Wolf
lnstitut fur Anorganische Chemie der Universitlt
Am Hubland, D-W-8700 Wiirzburg (FRG)
[**I This work was supported by the Deutsche Forschungsgerneinschaft
(SFB 347), the Fonds der Chemischen Industrie, and Degussa AG.
Angen Chem Int. Ed. Engl. 1992, 31, No. 8
Fig. 1. Crystal structure of 3b. Selected bond distances [A] and angles I"]:
0s-C1 1.83(1), 0s-P1 2.256(3), Os-P2 2.336(3), 0s-C11 2.466(4), 0s-C12
2.495(3), 0 s - 0 2 2.297(8), C1-01 1 34(1), C2-01 1.42(2); P1-0s-02 176.5(3),
P2-0s-CIl 167.3(1),C1-0s-C12 167 4(3), 0s-C1-01 138 8(9).
VCH Verlagsgesellschajt mbH, W-6940 Wernheim, 1992
0570-0833~92j0808-t02S$3.50+ .2Sj0
part of a six-membered chelate ring system. The intact
alkoxyalkylphosphane ligand is coordinated to the metal
center at P and 0.The 0s-C1 distance is significantly shorter
than that in related carbene osmium complexes such as [OsCI(=CH,)(NO)(PPh,) ] (1.92(1) A) and [OsCI,(=CHPh)(CO)(PPh,),J (1.94(1) .k):'] both of which also contain two
phosphane ligands.
For [OsC12(=CHOCH,CH,PiPr2)(q2-l)]
there are three
more possible stereoisomers besides 3 b A , B, and C which
are all chiral (Scheme 1). The question of which of the iso-
90 % yield after a mixture of 7" and 6 in hexane is heated
at 110 "C for 4 h (Scheme 3). Surprisingly, the reaction of 8
with CO leads to a monocarbonyl and not to a dicarbonyl
metal complex (isolated yield of 9: 77%); the reaction of 8
and phenylacetylene affords vinylidene-osmium derivative
10 quantitatively. The Os=C distance in 10 is 1.802(6) A,
comparable with the Os=C bond length in 3b.[31
CsHe. A. 4 h
0 = iPr,PCH,CH,OMe
Scheme 1
0 = iPr,PCH,C02Me
Scheme 3
mers A, B, or C corresponds to the complex 3a is still open.
Remarkably, in the single crystal of 3 b used for the X-ray
structural analysis only one enantiomer is present, which
according to the designation for octahedral complexes not
containing two cisoid bidentate or three bidentate ligands
has the A configuration (corresponding to the S configuration for tetrahedral compounds).*g1The enantiomeric purity
of the crystal could be due to packing effects or, alternatively, could originate from the mechanism of the reaction of
OsC1, . 3H,O with 1. We assume that the formation of
3a and 3 b occurs via hydridometal intermediates, and
that an insertion of the metal into the C-H bond of a OCH,
group is the primary step. In this context we note that in the
reaction of the olefin iridium compound [IrCl(C8H14)z]2
with 1, the metallated hydridoiridium complex
is formed nearly quantitatively.["'
The reaction of OsC1, . 3 H 2 0 with aminophosphane 4
proceeds in moderate yield (40-50 YO)to the carbene complex 5,and that of 2 with 4 in good yield (70-75%). In the
reaction of OsC1, . 3 H 2 0 with 4, several by-products are
formed which could not as yet be completely separated from
5.By comparing the 'H, I3C, and ,'PNMR data of 5 and 3b
we conclude that the compounds are structurally related.
In toluene at room temperature compound 10 exists in two
rapidly converting isomeric forms as is apparent from the
broadening of the 'H NMR signals. The free energy of activation AG* for the "open-and-close mechanism" (i.e. the
simultaneous cleavage and formation of one 0s-0 bond) is
53 kJmol-' ( T = 288 K).li21 The carbonyl complex was
found to be rigid at room temperature on the NMR timescale; owing to the large P-P coupling (290 Hz) of the signals
in the ,lPNMR spectrum there is no doubt that the two
nonequivalent phosphane ligands are trans to each other.['3]
Experimental Procedure
3 b : A suspension of 413mg (1.18mmol) of OsCI, .3H,O in 20mL of 2propanol was treated with 870 pL (4.70 mmol) of 1 and heated for 48 h at
reflux. After the solution was cooled, it was concentrated to 2 mL, and 25 mL
of ether was added. The yellow solid that precipitated was filtered off and
recrystallized twice from methanol/ether. A second fraction of 3 b was isolated
from the filtrate; yield 576mg (80%); m.p. 132°C.
5 : A solution of 214 mg (0.37 mmol) of 2 in 10 mL of benzene was treated with
234 pL (1.10 mmol) of 4 and heated for 72 h under reflux. After the solution
was cooled, the solvent was removed and the brown oily residue stirred with
10 mL of hexane to give a pale yellow solid; yield 166 mg (71 %) m.p. 176 "C.
8: A suspension of 119 mg (0.20 mmol) of 7 in 15 mL of hexane was treated
dropwise with 120 pL (0.61 mmol) of 6 and heated for 4 h at 110 "C in a sealed
tube. After the solution was cooled, orange crystals started to precipitate. To
enhance the precipitation, the reaction mixture was concentrated to 2 mL. The
orange crystalline solid was filtered off and washed with ether; yield 118 mg
(90%); m.p. 69°C.
10: A solution of 93 mg (0.145 mmol) of 8 in 5 mL of benzene was treated with
32 pL (0.29 mmol) of phenylacetylene and heated for 3 h at reflux. After the
solution was cooled, the solvent was removed and the residue stirred with a
small amount of hexane to give a salmon-colored solid; yield 103 mg (96%);
m.p. 154°C.
Received: March 12, 1992 [Z 5236 IE]
German version: Angew. Chem. 1992, 104,1079
Scheme 2.
An osmium complex of the general type [OsC12(q2-iPr2PY ) 2 J (Y = heteroatom unit), originally expected as the
product of the reaction of 2 and 1, is accessible with the
methyloxycarbonylphosphane 6. Compound 8 is isolated in
Verlagsgeselischufi mbH, W-6940 Weinheim, 1992
[l] E. 0 . Fischer, A. Maasbol, Angew. Chem. 1964,76,645;Angew. Chem. Inr.
Ed. Engl. 1964, 3, 580.
[2] a) K. H. Dotz, H. Fischer, P. Hofmann, F. R. Kreissl, U. Schubert, K.
Weiss, Transition Meral Carbene Complexes, Verlag Chemie, Weinheim,
1983, Chap. 1; b) Advances in Metal Carbene Chemistry (Ed.: U. Schubert)
(NATO AS1 Ser. Ser. C 1989,269);c) P. J. Brothers, W. R. Roper, Chem.
Rev. 1988,88,1293-1326.
[3] B. Weber, Diplomarbeit, Universitat Wiirzburg, 1992.
[4] H. Werner, A. Stark, M. Schulz, J. Wolf, Organomerallics 1992, f f , 11261130.
0570-0833192j0808-1026 S 3 . 5 0 t ,2510
Angew. Chem. hi.Ed. Engl. 1992, 31, N o . 8
[5] P. R. Hoffman, K. G. Caulton, J. Am. Chem. Soc. 1975, 97,4221-4228.
[6] a) M . A. Gallop, W. R. Roper, Adv. Organomet. Chem. 1986,25,121- 198;
b) W. R. Roper, .
Orgunomer. Chem. 1986, 300, 167-190.
[7] H. Werner, W. Knaup, M. Schulz, Chem. Ber. 1991, 124, 1121-1125.
[8] Crystals from methanol/diethyl ether (1 : 5 ) ; crystal size 0.1 x 0.2 x 0.4 mm;
orthorhombic, space group P2,2,2, (No. 19); Z = 4; u = 10.459(2),
b = 14.232(3), c = 15.925(3) A, V = 2370.4 A3,pEslcd
= 1.71 g ~ m - max.
~ ;
28 = 52" (Mo,., 1 = 0.70930 A, graphite monochromator, o/28-scan,
T = 293 K); 2645 independent reflections, 1645 observed IFo > 3u(Fo)],
Lorentz, polarization, and empirical absorption corrections
( p = 57.4 cm-', Y-scan method, min. transmission 88.2%); Patterson
method (SHELXS 86). refinement with program package SDP (EnrafNonius). The hydrogen atoms were calculated for ideal geometry by the
riding method and included in the final refinement (full-matrix leastsquares); R = 0.045, R , = 0.049; reflex/parameter ratio 7.32; residual
electron density + 1.S6/-0.91 e k 3 . The absolute configuration at the
osmium center was determined after the anomalous dispersion had been
taken into account. For the other enantiomer R = 0.060 and R , = 0.069.
Further details of the X-ray structure analysis are available on request
from the Fachinformationszentrum Karlsruhe, Gesellschaft for wissenschafthch-technische Information mbH, D-W-7514 Eggenstein-Leopoldshafen 2 (FRG), on quoting the depository number CSD-56271, the
names of the authors, and the journal citation.
[9] T. E. Sloan in Top. Stereochem. (Ed.: G. L. Geoffroy), 1981, f2, 1-36.
[lo] M. Schulz, Ph.D. Thesis, Universitlt Wiirzburg 1991.
[Ill M. Aracama, M. A. Esteruelas, F. J. Lahoz, J. A. Lopez, U. Meyer, L. A.
Oro, H. Werner, Inorg. Chem. 1991, 30, 288-293.
1121 For further examples see: A. Bader, E. Lindner, C o d . Chem. Rev. 1991,
[I31 a) P. Braunstein, D. Matt, Y. Dusausoy, Inorg. Chem. 1983, 22, 20432047; b) E. Lindner, U. Schober, R. Fawzi. W Hiller, U. Englert, P.
Wegner, Chem. Ber. 1987, 120, 1621- 1628.
Complexes 2 a, b form black crystals which can be handled in
air for a short time. These crystals dissolve well in hexane
and are even more soluble in benzene and dichloromethane.
[(Cp"Rh),(E,-E,)(RhCp"),l 2 % b
190°C. 3 h
[ ( ( C p " R h ) ( ~ ( , ~ ~ : ~ ~ - E3a,
, ) j ,bl
a: E = P, b: E = A s ; Cp" =I,3-tBuzC,H,
The X-ray structure
(Fig. 1) shows that the
polycyclic Rh,P,, framework of 2a is centrosymmetric and
also that the all-phophorus analogue of dihydrofulvalene
(structure type B) is arranged so that the Rh atoms can
achieve the 18 valence electron configuration; formally, Rh 2
receives the four 7c electrons of the double bonds P2-P 3 and
P4-P5 [2.143(2) and 2.148(2) A, respectively], and Rh 1 has
the pair of nonbonding electrons on P I at its disposal, as
well as a bonding electron pair as a result of the opening
(oxidative addition) of the P3-P4 edge [2.624(2) A]. Thus,
Double Open-Edged PI Dihydrofulvalene
as a 16-Electron Donor Ligand""
By Otto J. Scherer,* Bernd Hobel,
and Gotthelf Wolmershauser
Since the discovery of the stabilization of P, As, and several other P,, and As, molecules by complexation approximately 20 years ago, it has become clear--especially in very recent
times-that no limit has yet been placed on the structural
variety of such acyclic, cyclic, and polycyclic Pn and As,
ligands.['I Whereas theory predicts polycyclic molecules as
being the most stable isomers for P, to P,
the cyclo-En
molecules (E = P, As; n = 4-6), isovalent with the carbocyclic (CH), 7c systems, can also be stabilized by coordination."'
Starting from 1 and E, (E = P, As) we have now been able
to synthesize En building blocks of this type, namely, PI, and
As,, (structure type B). These are analogous to the dihydro-
Fig. 1. Crystal structure of 2a. Selected bond lengths [A] and bond angles ["I:
PI-PI' 2.184(2), P1-P2 2.192(1), P1-P5 2.193(1), P2-P3 2.143(2), P4-P5 2.148(2),
P3 ' 'P4 2.624(2), Rhl-PI 2.209(1), Rhl-P3' 2.329(1), R h l - P4 2.325(1), Rh2P2 2.406(1), Rh2-P3 2.435(1), Rh2-P4 2.443(1), Rh2-P5 2.401(1), Rhl-Cp"
(center) 1.95, Rh2-Cp" (center) 1.90; Pl'-PI-P2 101.7(1). PI'-Pl-P5 102.2(1),
PI'-PI-Rhl lll.O(l), P2-PI-P5 91.2(1), Pl-P2-P3 100.2(1), P2-P3-P4 96.7(1),
P3-P4-P5 96.9(1), P4-P5-P1 99.5(1), P3-Rhl'-P4 68.6(1). P3-Rh2-P4 65.1(1),
Rhl'-P3-Rh2 112.6(1), Rhl'-P4-Rh2 112.4(1), Pl-P2-Rh2 93.5(1), P1-PS-Rh2
93.6(1), P2-Rh2-P5 81.4(1). @ = CtBu.
PI, functions as a 16-electron donor ligand. The structure of
the [Rh 2,P 3,P 2,P 5,P4,Rh 1'1 fragment differs only slightly
from the analogously constructed binuclear complex 41s1(for
2a one has to imagine that P 2 is connected to P5, Fig. 1).
The Rh 1-P 1 distance (2.209(1) A) is similar to the Rh-P
fulvalene A and are coordinated in an open-edged form as
ligand in the tetranuclear rhodium complexes 2 [Eq.(a)].
Prof. Dr. 0. J. Scherer, DipLChem. B. Hobel, Dr. G. Wolmershaiuser'']
Fachbereich Chemie der Universitlt
Erwin-Schrodinger-Strasse, D-W-6750 Kaiserslautern (FRG)
X-ray structure analyses
This work was supported by the Fonds der Chemischen Industne. We
thank Johnson Matthey, Reading, England, for their generous loan of
Angeu,. Chrm. Int. Ed. Engl. 1992, 31, No. 8
[Cp'Rh(p, q4: '1' :qi-P4)Rh(CO)Cp'J
4, Cp' = C,Me4Et
6, C p = C,H,
distances of 2.200(2) and 2.213(2) 8, found in the binuclear
complex 5.16]The average value of the P-P distances (2.17 A)
in 2a is significantly shorter than that for the same distances
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carbene, alkoxylalkyl, osmium, aminoalkylphosphanes, double, complexes, metalation
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