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Radical Complexes of Molybdenum as Reactive Intermediates.

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Table I . Yields (from chromatography and/or recrystallization) and melting or boiling point of the products is)-( I l ) The reaction of the lithium derivatives (2j and (3) lo
give (6) and (7) respectively E = D. produced in both cases ~ 9 5 %
monodeulerated compounds ('H-NMR. MS analysis). All spectroscopic data and elemental analyses are
consistent with the structures given. For the preparation and data of the aducts (2) and /3). see ref. [4b. c].
~
~~~~
Educt
(Li derivative)
Reagent
Product
E
Yield [%I
M. p. ['TI or
B. p. [ "C/Torr]
(21
12)
(2)
Methyl iodide
I-Chloro-, 1-Bromo-. 1-lodoctane
2-Iodopropane
lodocyclohexane
(64
(66)
CH,
C~HII
(CH,)lCH
c-C,Ht i
94
85. 85. 86
90
89
66
40
71
I25
3.4-Methylenedioxybenzylbromide
(be)
77
101
(6fi
I4
Trimethylchlorosilane
Tributyltin chloride
Propanal
(6g)
(6h) and (R)
(CH,)Si
(C&)Sn
CzH5CH(OH)(3: I ]
88
84
69
2 10/0.01
I29
12)
Benzaldehyde
(61) and (9)
C,H,CH(OH) 13.5: I ]
78
(2)
C yclopentanone
Benzophenone
Iodine
Methyl iodide
Methyl iodide
(6;)
(CH2)aC(OH)
(C,H<)ZC(OH)
75
83
45
59
56
90
77
88
85
71
(2)
(2)
(2)
(21
(601
(3)
(2)
(6C)
164
(6k)
(10)
(11)
(1)
(54
(12)
(12)
(12) lcl
5
)(;
(3)
KOH
(1)
1717)
KOH
(54
(no)
(6;)
CHI
(74
CHI
(CH1)4C(OH)
CH,
Ill
105/0.02
160
76-78
I32
182
243
80
97-98
I W 4 [a]
125/14 [a]
106
I50/70 [a]
187 [b]
[a] Boiling point on Kugelrohr distillation. [b] Picrale; m.p. 187 " C (Beilsrein: Handbuch der Organischen Chemie. Vol. 20. €11 185). [c] 1.5 equivalents
E
(I), X
=
(I), X
=
H
COC(CH3)s
( 3 ) , X = COC(OH)(CH3)2
(5), X = H
( 6 ) , X = COC(CH3)3
(7), X = COC(OH)(CHZ),
Q N . x
R*OX
(8). R = CzH,, X = COC(CH3)3
( 9 ) . R = CSH,, X = COC(CH3)3
(lo), X
= COC(CH,),
suitable reaction conditions for deprotonation of the corresponding benzamides.
Received: September 29. 1980 [Z 667 I€]
German version: Angew. Chem. 93. 125 (1981)
CAS Registry numbers:
( I ) , 91-21-4; (2). 76068-XI-0: (3). 76068-82-1; ( 5 ~ ) 4965-09-7:
.
(50). 76068-83-2.
( 5 ~ )76068-84-3:
.
(Cia).76068-85-4; (66). 76068-86-5; (6c). 76068-87-6 (6d). 760688R-7: ( l e i . 76068-89-8: /6A. 76068-90-1: (6g). 76068-91-2: (6h). 76068-92-3. (61).
76068-93-4. (6~).
76068-94-5: (6k). 76068-95-6. (7a). 76068-96-7, (9). 76068-97-8:
(10). 76068-98-93 i l l ) . 76068-99-0: (12). 75339-25-2; f8).76069-00-6: methyl iodide. 74-88-4: I-chlorooctane. 1 11-85-3: I-bromooctane. 1 11-83-1. I-iodooctane.
629-27-6. 2-rodopropane. 75-30-9: iodocyclohexane 626-62-0: 3.4-methylendioxvhenn I hrcmidt.. 7 6 3 5 - 174: trimeihylchlorocilane. 75-77-4: tributylin
chloride. Y'l5-45-Y. prvpdnal. 123-3X-6. benzaldehyde. 100-52-7. cyclopentanone.
120-92-3; benf.ophenone, 119-61-9
Angew. Chem. Inr. Ed Engl. 20 (19x1) No. I
[ l ] A. Reissert. Ber. Dtsch. Chem. Ges. 38, 1603. 3415 (1905): Review: ?
, D.
Popp. Adv. Heterocycl. Chem. 24. 187 (1979). and cited literature: see also G.
Srork, R. M. Jacobson, R . Levitz, Tetrahedron Lett. IY79, 77 I .
121 D. Seebach. Angew. Chem 91.259 (1979): Angew. Chem. Int. Ed. Engl. I8.
239 (1979).
[3] D. Seebach. D. Enders. Angew. Chem. 87. I (1975): Angew. Chem. Int. Ed.
Engl. 14. 15 (1975). B. Renger. D. Seebach. Chem. Ber. 1 1 0 . 2334 (1977): T.
Hassel. D. Seebach. Angew. Chem. 91, 427 (1979): Angew. Chem. Int. Ed.
Engl. 18. 399 (1979): W. Lubosch, D. Seebach. Helv. Chim. Acta 63. 102
(f980): W. Wykyprel. D Seebach, Tetrahedron Lett. 14x0. 1927.
141 a) N.N-Dimethylpivalamide could not be metalated without self-condensation
131. b) From ( 1 ) and pivaloyl chloride/Et3N ether at R. T., 9U96 yield,
m . p . = 6 5 'C. c) From (I-chlorocarbonyl-I-methyl)elhylacetate/(lj/Et,N in
ether. ( I ) X=COC(OAC)(CHx), (m p.=61-62"C) is first produced, whose
alkaline hydrolysis gives (3) (m.p.=78"C). Total yield 74% relative to l l j .
[5] With /err-butyl iodide no alkylated product is formed, which instead of a radical mechanism [cf. K. Deuchetr. U. Herfensrein. S. Hunig. C Wehncr.
Chem. Ber. 112, 2045 (1979)l or a capfodarita radical stdbi~ization( H G.
Viehe. R. Merenyi, L. SreNu. 2. Tanousek, Angew. Chem. 91. 982 (1980): Angew. Chem. Int. Ed. Engl. 18. 917 (1979)). suggests an SN2-mechantsm.
[6] Cf. M . - A . Siedried. H. Hilperr. M Re?. A. S. Dreiding. Helv. Chim. Acta 6.Z.
938 (19x0).
[7] The amides (6j are just as stable towards hydrolysis by aqueous acid and alkali solutions as they are towards reaction with boiling ethylendiamine or diisobutylaluminum hydride (DIBAH) With LiAIHI or LiBHE1, a mixture of
(S) and the N-neopentyl derivative were isolated
[8] A. Hujos: Complex Hydrides. Elsevier, Amsterdam 1979; J. Vrf. Eastman
Org. Chem. Bull. 43 (3). 1 (1970): J. M d e k . M. Cern,:. Synthesis IY72, 217.
191 The diastereomerically pure amides (6). E = CH(0H)R are unfortunately
converted into mixtures of diastereoismers (8)or (9). This type of rearrangement has also been observed in peptides having hydroxyalkyl side chains. see
e.g. A. Ruegger. M . Kuhn, H Lichri. I l . - R . Loorlv. R Huguenm. Ch. Quiquer~
ez. A. run Warrburg, Helv. Chem. Acta 5Y. 1075 (1976).
Radical Complexes of Molybdenum as Reactive
Intermediates
By Dieter Fenske and Anestis Christidis"'
Dedicated to Professor Withelm KIemm on the occasion
of his 85th birthday
In ligand exchange reactions of metal(0) complexes such as
C O ~ ( C Oor) ~Pd(PPh& with ditertiary phosphanes such as
['I
Priv.-Do7. Dr. D. Fenske, A. Christidis
knorganisch-chemisches Institut der Universitat
Gievenbecker Weg 9. D-4400 Munster (Germany)
0 Verlag Chemre, GmbH. 6940 Weinheim. 1981
0570-0X33/81/0~01-012~ S 02.50/0
I29
bis(dipheny1phosphino)maleic anhydride (1) and -N-methylimide (PP) we observed the formation of paramagnetic complexes in which the coordination of the bidentate ligand to
the metal is accompanied by an electron transfer from the
metal into a n* orbital of the ligand['.2'. The ligand is converted into a complex bonded radical anion (PP-), as illustrated by the formulas Co'(CO),(PP-) and Pd2+(PP-)2.
Such complexes are in part extremely reactive, so they only
occur as non-isolable intermediates, e.g. in the reaction of
Ni(CSH5), with (1)"'. We have now observed a further secondary reaction to the deep-brown radical complexes (2) and
(3) which are obtainable from [Mo(C,H,)(CO)~], and (1) or
(PP), respectively.
tained yellow crystalline (5), which, in contrast to (3), is diamagnetic. According to the IR spectrum, (5) contains CO ligands; the ligand PP has somewhat modified IR bands. The
phosphorus atoms are no longer symmetry equivalent (31PNMR: S = - 26.5 and -72.9, referred to 85% H3P04;
Jp = 10 Hd4'. A crystal structure determinatior~[~]
enabled
(5) to be characterized and, at the same time, provided an ex13) + P h C H ,
+
planation of the secondary reaction that takes place on prolonged heating in boiling toluene [eq. (a)]. The formation of
1,2-diphenylethane could be demonstrated.
(I), X
= 0
( P P ) , X = NCH3
(7). X = 0
( 3 ) . X = NCH3
The reaction of [Fe(CSHS(C0)2]2with (PP) or (1) analogously leads to paramagnetic complexes of the type
Fe (PP-)(C5HS)(CO). However, we restricted our studies to
(3) and its secondary reactions.
The following findings show that in the formation of (3)
an unpaired electron is transferred from molybdenum into a
T* orbital of the complex bonded ligand.
1. The magnetic moment of (3) is obtained from the susceptibility pemwhich follows the Curie law, perf=1.72 p B (at
295 K). Accordingly. an unpaired electron is present.
2. The ESR spectrum of (3) in tetrahydrofuran consists of
a triplet of three groups of signals in the intensity ratio 1 :2: 1.
The triplet structure is due to coupling between unpaired
electron and P nucleus, the fine structure of each triplet component to corresponding coupling with the N and H nuclei of
the NCH3 group (ap= 9.28, aN= 1.84, uH = 0.68 gauss)[3].
3. In the IR spectrum the PCO bonds of the ligand PP on
complexation to (3) are lowered by about 80-100 cm-I, as
we have previously always observed when such ligands are
transformed into radical
4. Oxidation of (3) with I2 in CHzC12leads to the iodide (4)
of the cation formed by withdrawal of electrons from (3). (4)
+
is diamagnetic and the K O bands of the ligand PP occur in
the same region as the free ligand. A crystal structure analysis confirms the presence of the complex cation and the anionic nature of the iodine outside of the coordination shell.
The yield of (3) is satisfactory only when the synthesis is
carried out in a relatively short reaction time; a secondary
reaction occurs on prolonged reaction in boiling toluene. On
heating a solution of (3) in toluene for several days we ob-
130
@ Verlag Chemie, GmbH. 6940 Weinheim, 1981
uc4
Fig 1. Molecular structure of the molybdenum complex (5) in the crystal 151
(-5) crystallizes from toluene as a 1 :1 solvate with the solvent. Figure 1 shows the molecular structure, in which the H
atoms except that on C51 added during the formation of (5)
from (3) have been omitted; it was unequivocally located in a
difference Fourier synthesis. The formation of a CH bond at
C51, which previously belonged to the C - C bond in the
maleimide system of (3). follows from the sum of the angles
of the bonds from C51 to PI, C52 and C53 (332"). The atoms
C52, C53, C54 and N in the five-membered ring, on the other hand are planar coordinated.
By addition of the H-atom, C51 becomes a center of chirality, and is probably formed by participation of the previously unpaired electron in the PP radical of (3). The electrons of the original Cr-C bond are shifted to C52. The
strong influence of the new bond system on the bond lengths
in the Mo(H-PP-) part of the molecule of (5) follows from
the following data (in pm):
Mo-PI
Pl-C51
CSI-C52
N-C53
052-C53
=
=
=
=
=
0570-0833/81/0101-0130
250(0.1)
184(1)
fSl(7)
134(1)
1230)
$ 02.50/0
Mo-P2
P2-C52
CSt-C53
N-C54
051-C54
=
=
=
=
=
256(0.1)
175(1)
!53(1)
145(1)
123(1)
C52-C54 = !40( 1 )
Angew. Chem. Int. Ed. Engl. 20 (1981) No. 1
These distances indicate considerable mesomeric interaction of the free electron pair on C52 with the )C=O groups,
with the free electron pair on the imide nitrogen, and with
the phosphorus atoms.
The cyclopentadiene ring in (5) is pentahapto bonded to
molybdenum. The bond lengths in the M O ( C O ) ~ ( C ~ part
H~)
of the molecule are normal (in pm):
Mo-CP
Mo-ClO
CIO-OCI
= 230-236
= 199(1)
= 114(1)
CP-CP
Mo-C20
CZO-OC2
= 139-142
= 196(1)
= 115(1)
A further proof for the constitution of (5) is its smooth oxidation to (4) [eq. (b)]:
(5)
[3 + 21-cycloadducts (2a) and (2b), respectively, of the iminophosphane (1) and the heteroallenes
In an attempt to generate the still unknown bis(methy1ene)phosphorane (3c) in a similar way from the analogue
l,2,4A3-diazaphospholine (2c) of (2b), we obtained the A'phosphirane (4) isomeric to the phosphorus ylide (3c).
+ Iz + (4) + HI
(b)
Procedure
A solution of [MO(C,H,)(CO>,]~(1.2 g, 2.45 mmol) and
(PP) (2.36 g, 4.91 mmol) in boiling toluene is stirred until
evolution of CO is complete. Brown (3) crystallizes from the
dark-brown solution; yield 95%.-The iodide (4) is prepared
by oxidation of (3) (2.38 g, 3.41 mmol) with iodine (0.435 g,
3.42 mmol) in ether/l,2-dichloroethane(1 : 1) at "C; dark-red
crystals, yield 80%.-When (3) is heated for several days at
80°C in toluene, (5) is obtained as large, yellow crystals;
yield 40-60%.
Received: April 30, 1980 [Z 675 IE]
German version: Angew. Chem. 93. 113 (1981)
[ I ] D. Fenske, Angew. Chem. 88, 415 (1976); Angew. Chem. Int. Ed. Engl. IS.
381 (1976); Chem. Ber. 112. 363 (1979); W Bensmann, D. Fenske, Angew.
Chem. 90,488 (1978): Angew. Chem. Int. Ed. Engl. 17, 462 (1978).
121 W. Bensmann, D. Fenske. Angew. Chem. 9f. 754 (1979): Angew. Chem. Int.
Ed. Engl 18. 677 (1979).
[3] We thank Dr. Korth. Universitat Essen, for recording and discussing the ESR
spectrum.
[4] We thank Dr. Heckmunn, lnstitut fur Anorganische Chemie der Universitat
Stuttgart for measuring the "P-NMR spectra.
[ 5 ] (Si.1 toluene, space group PZ,/n; u=964.2(4). b = 1457.0(6), c=2602.5 (9)
pm. p=97.45(3)". 2 = 4 . psdlL=1.4l.p,,,,=1.43 g/cm3. ~ ( M o K , , ) = 4 . c8 m - '
Low-temperature measurement ( - 13O"C), Syntex-PZ, diffractometer, up to
2 8 = 50"; 6542 reflections, 5002 with I > 1.96a(n. Solution of structure: heavy atom method, anisotropic refinement of all site parameters and temperature factors. R , =0.048, R2 =0.046. All H-positions could be found in a final
difference Fourier analysis.
Nz-Elimination from a [3+ 2]-Cycloadduct of
Diazoalkane and Amino(methy1ene)phosphane to
give a A3-Phosphirane[**]
By Edgar Niecke, WoEfgang W. Schoeller, and
Dirk-Andreas Wildbredti']
Kinetically stable phosphorus ylides such as (3a) and (3b)
can be obtained by N2-elimination from the thermolabilel']
The highly electrophilic [bis(trimethylsilyl)amino](trimethylsilylmethy1ene)phosphane (5), which is isoelectronic to
( l ) ,proved to be a suitable precursor for the synthesis of (2c).
(5) can be readily obtained in a one-pot reaction and can be
smoothly converted into the desired [3 + 21-cycloadduct (2c)
by reaction with 1-diazo-2,2-dimethylpropane.
1) R2CHMgCI, - MgOZ
2) R2NL1, - LiCl
3) 1 5 0 T - R C I
RCHN2
* R2N-P*
C -R
/2cl
The composition and constitution of (5), (2c) and (4) are
confirmed by elemental analysis, mass spectra, NMR data
(Table 1) and, in the case of (5), also by the IR spectrum. A
noticeable feature on comparison of (5) with the known methylene pho~phanes'~'
is the downfield shift of the "P-NMR
signal (6=308.7) and the upfield shift of the I3C-NMR signal (6= 147.9); this would indicate considerable changes in
the polarity of the P=C bond and explain the high reactivity
of (5) towards dipolar and oxidative additionf4'. The high
value for 2Js,cp
(40.5 Hz) would suggest existence of the sterically favorable Z-form, which has been demonstrated for the
corresponding imine derivative ( l ) I 5 1 . The P-C valence vibrations (vP cH=1120, v p cD=1085 cm-') can be identified by comparison of the very similar IR spectra of (5) and
(I)''] and of the derivative of (5) deuterated at the methylene
carbon.
In the [3 + 21-cycloaddition product (2c) the 31P-nucleusis
drastically shielded (A6 = 300 ppm), as is also observed in the
transition from (1) to (2a). The symmetry of (2c)-and thus
Table 1. "P-. 'H-, "C- and "'SI-NMR dara of the compounds fS). f2cl and (4)
la1
S(3'P)
308.7
3.6
&('H)(JHP IHzl)
0.27 (1.3)
PNSiMe,
PCSiMe,
0.11 (1.3)
PCH(Si)
7.13 (18 2)
PCH(C)
PCCMei
-
008
0.14
4.65
4.81
1.10
- 110.5
(1.3)
(0.7)
(2.5)
(0.5)
(0.2)
0.20
0.16
0.59
2.19
0.93
(1.0)
(0.2)
(4.9)'"'
(1.8)lh'
(0.7)
S("C) (Jcr [Hz])
(21
(3)
SihIe3,R'= C M e 3 ; ( a ) : A = N , (h): A = C H
(1)
R
['I
["I
=
Prof. Dr. E. Niecke. Priv.-Doz. Dr. W. W. Schoeller. DipLChem. D:A.
W ildbredt
Fakultat fur Chemie der Universitat
Universitatsstr.. D-4800 Bielefeld (Germany)
This work was supported by the Fonds der Chemischen Industrie.
Angew. Chem. Inl. Ed. Engl. 20 (1981) No. 1
PNSiC,
PCSiC,
PC(Si)
PC(C)
PCC
PCCC,
3.5 (6.7)
0.8 (9.0)
147.9 (70.3)
-
4.2 (7.4)
-1.4
(5.0)
9 0 4 (54.1)
110.0 (46.1)
35.6 (29.9)
24.0 (8.9)
4.7 (5.7)
2.9 (4.5)
21.8 (59.1)
46.7 (56.4)
33.1 (11.2)
30.9 (6.0)
S(*"Si) (Js,P IHzl)
PNSi
6.5 (4.4)
PCSi
-6.5 (40.5)
[a] 30% solution in CDCI,, H3P0, as external ("P) and TMS ( ' H , "C. "Si) as
internal standard, 25 "C.
[b] ' " J ~ ~ = 1 3 . 7
HZ
0 Verlag Chemie, GmbH. 6940 Weinheim. 1981
0S70-0833/81/0101-0131
8 02.50/0
131
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