Synthesis and properties of (η2-C,X) chelate arylcarbene complexes [Fe(C5Me5)(L){η2-C(OMe)C6H 4-o-X}][OTf] (L = CO, PMe3; X = OMe, Cl)

Article abstract of DOI:10.1021/om960711z

The methoxycarbene complexes [Fe(C₅Me₅)(CO)₂{=C(OMe)C₆H ₄-o-X}][OTf] (2a, X = OMe; 2b, X = Cl) are good precursors of the corresponding (η²-C,X) chelate carbene complexes [Fe(C₅Me₅)(CO){η²-C(OMe)C₆H ₄-o-X}][OTf] (OTf = CF₃SO₃) (5a,b). The η₂-chloro derivative 5b has been characterized by X-ray diffraction, confirming the formation of a five-membered ring metallacycle. All the new carbene complexes, including the nonheteroatom-stabilized carbene complex [Fe(C₅Me₅)(CO)₂{=C(H)C₆H ₄-O-OMe}][OTf] (4a), have been fully characterized by ¹H and ¹³C NMR spectrocopy. The lability of the chelating o-substituent is chemically demonstrated by the formation of the corresponding neutral iodo carbene complexes [Fe(C₅Me₅)(CO)(I){η¹-C(OMe)C ₆H₄-o-X}] (6a,b), the competitive O-demethylation process being thus inhibited. Selective ligand exchange reactions of 5a,b afford various substituted complexes such as [Fe(C₅Me₅)(CO)_n(PMe₃){η ^x-C(OMe)C₆H₄-o-OMe}][OTf] (11, n = 1, x = 1; 12, n = 0 x = 2); the mono- and bis(acetonitrile) complexes [Fe(C₅Me₅)(L)(CH₃CN){η¹ C(OMe)C₆H₄-o-Cl}][OTf] (14, L = CH₃CN; 15, L = CO) have been also synthesized. The reactivity of 5a toward NaBH₄ is highly dependent on the solvent. Specific hydride addition occurs in 9:1 THF-MeOH to give the expected complex [Fe(C₅Me₅)(CO){η²-CH(OMe)C ₆H₄-o-OMe}] (9) as a single diastereoisomer, while reduction in pure THF affords the organoborohydride complex [Fe(C₅Me₅)(CO){η²-H₂BHCH ₂C₆H₄-o-OMe}] (10). The latter reaction involves a formal insertion of BH₃ into a Fe-C bond, promoted by the potential vacant coordination site. The carbene ligand is easily displaced and recovered as free carbonylcontaining organic substrates (aldehyde or ester) from both types of carbene complexes upon bubbling of O₂.

Full text of DOI:10.1021/om960711z

124
Organometallics 1997, 16, 124-132
Syn th esis a n d P r op er ties of (η2-C,X) Ch ela te Ar ylca r ben e
Com p lexes [F e(C5Me5)(L){η2-C(OMe)C6H4-o-X}][OTf]
(L ) CO, P Me3; X ) OMe, Cl)
Ge´raldine Poignant, Sylvain Nlate, and Ve´ronique Guerchais*,†
Laboratoire de Chimie des Complexes de Me´taux de Transition et Synthe`se Organique, URA
CNRS 415, Universite´ de Rennes 1, Campus de Beaulieu, 35042 Rennes Cedex, France
Andrew J . Edwards and Paul R. Raithby
Cambridge Centre for Chemical Crystallography, University Chemical Laboratory, University
of Cambridge, Lensfield Road, Cambridge CB2 1EW, United Kingdom
Received August 20, 1996X
The methoxycarbene complexes [Fe(C5Me5)(CO)2{dC(OMe)C6H4-o-X}][OTf] (2a , X ) OMe;
2b, X ) Cl) are good precursors of the corresponding (η2-C,X) chelate carbene complexes
[Fe(C5Me5)(CO){η2-C(OMe)C6H4-o-X}][OTf] (OTf ) CF3SO3) (5a ,b). The η2-chloro derivative
5b has been characterized by X-ray diffraction, confirming the formation of a five-membered
ring metallacycle. All the new carbene complexes, including the nonheteroatom-stabilized
carbene complex [Fe(C5Me5)(CO)2{dC(H)C6H4-o-OMe}][OTf] (4a ), have been fully character-
ized by 1H and 13C NMR spectrocopy. The lability of the chelating o-substituent is chemically
demonstrated by the formation of the corresponding neutral iodo carbene complexes
[Fe(C5Me5)(CO)(I){η1-C(OMe)C6H4-o-X}] (6a ,b), the competitive O-demethylation process
being thus inhibited. Selective ligand exchange reactions of 5a ,b afford various substituted
complexes such as [Fe(C5Me5)(CO)n(PMe3){ηx-C(OMe)C6H4-o-OMe}][OTf] (11, n ) 1, x ) 1;
12, n ) 0, x ) 2); the mono- and bis(acetonitrile) complexes [Fe(C5Me5)(L)(CH3CN){η1-
C(OMe)C6H4-o-Cl}][OTf] (14, L ) CH3CN; 15, L ) CO) have been also synthesized. The
reactivity of 5a toward NaBH4 is highly dependent on the solvent. Specific hydride addition
occurs in 9:1 THF-MeOH to give the expected complex [Fe(C5Me5)(CO){η2-CH(OMe)C6H4-
o-OMe}] (9) as a single diastereoisomer, while reduction in pure THF affords the orga-
noborohydride complex [Fe(C5Me5)(CO){η2-H2BHCH2C6H4-o-OMe}] (10). The latter reaction
involves a formal insertion of BH3 into a Fe-C bond, promoted by the potential vacant
coordination site. The carbene ligand is easily displaced and recovered as free carbonyl-
containing organic substrates (aldehyde or ester) from both types of carbene complexes upon
bubbling of O2.
In tr od u ction
coordinating ortho-substituent X (X ) OMe, Cl) on the
C6 ring; the presence of this dissymmetrically substi-
tuted ring allows (i) additional conformational informa-
tion to be obtained and (ii) access to (η2-C,X) chelate
carbene complexes. The chelating group X is expected
to dissociate easily in order to favor reaction within the
coordination sphere of the metal. Moreover, these
complexes constitute useful precursors for the complex-
ation of new ligands, especially when direct routes
cannot be applied due to side reactions with the carbene
ligand.
Arylcarbene complexes represent good models for the
investigation of the structural, spectral, and chemical
reactivity patterns of iron-carbene complexes:1 the
absence of â-hydrogen atoms inhibits any side rear-
rangement reactions, and the thermal stability of these
electrophilic species is enhanced by the electronic de-
localization of the positive charge into the aryl group.1,2
Our investigations deal with arylcarbene complexes
[Fe(C5Me5)(CO)2{η1-C(R)C6H4-o-X}]+, which possess a
† E-mail: guerchai@univ-rennes1.fr.
X Abstract published in Advance ACS Abstracts, November 15, 1996.
(1) (a) Brookhart, M.; Studabaker, W. B. Chem. Rev. 1987, 87, 411
and references therein. (b) Petz, W., Ed. Iron-Carbene Complexes;
Gmelin-Institut; Springer-Verlag: Berlin, 1993. (c) Doyle, M. P. Chem.
Rev. 1986, 86, 919.
In a preliminary communication,3 we reported the
original reactivity of the (η2-C,O) chelated carbene
complex [Fe(C5Me5)(CO){η2-C(OMe)C6H4-o-OMe}][OTf]
(2a ), precursor of the organoborato complex [Fe(C5-
Me5)(CO){η2-H2BHCH2C6H4-o-OMe}] (10). This led us
to extend our investigations to the related (η2-C,Cl)
(2) (a) Brookhart, M.; Nelson, G. O. J . Am. Chem. Soc. 1977, 99,
6099. (b) Guerchais, V. Bull. Soc. Chim. Fr. 1994, 131, 803 and
references therein. Guerchais, V. J . Chem. Soc., Chem. Commun. 1990,
534. (c) Bly, R. S.; Silverman, G. S. Organometallics 1984, 3, 1765. (d)
Bly, R. S.; Hossain, M. M.; Lebioda, L. J . Am. Chem. Soc. 1985, 107,
5549. (e) Bly, R. S.; Bly, R. K.; Hossain, M. M.; Lebioda, L. Raja, M. J .
Am. Chem. Soc. 1988, 110, 7723. (f) Bly, R. S.; Silverman, G. S.; Bly,
R. K. J . Am. Chem. Soc. 1988, 110, 7730. (g) Bly, R. S.; Bly, R. K. J .
Chem. Soc., Chem. Commun. 1986, 1046.
(3) Nlate, S.; Gue´not, P.; Sinbandhit, S.; Toupet, L.; Lapinte, C.;
Guerchais, V. Angew. Chem., Int. Ed. Engl. 1994, 33, 2218.
S0276-7333(96)00711-X CCC: $14.00 © 1997 American Chemical Society

Arylcarbene Complexes
Organometallics, Vol. 16, No. 1, 1997 125
Sch em e 1
complex [Fe(C5Me5)(CO){η2-C(OMe)C6H4-o-Cl}][OTf] (2b),
since substitution-labile halocarbon complexes are cur-
rently of structural and synthetic interest, especially for
the activation of small molecules.4
We report here a full account of the synthesis,
structure, and reactivity of the (pentamethylcyclopen-
tadienyl)iron-carbene complexes [Fe(C5Me5)(CO){η2-
C(OMe)C6H4-o-X}][OTf] (X ) OMe, Cl).
Resu lts a n d Discu ssion
Syn t h esis of t h e Dica r b on yl Ca r b en e Com -
p lexes. Reactions of the metal anion [Fe(C5Me5)(CO)2]-
[K] with acylating or alkylating agents provide a
convenient route to metal-acyl5 or -alkyl complexes,
whereas the use of aryl halides is generally inefficient.6
The o-anisoyl complex [Fe(C5Me5)(CO)2{C(O)C6H4-o-
OMe}] (1a ) is thus prepared in 80% yield after extrac-
tion and crystallization in ether. The ortho-iodo-
substituted analogue is not accessible in this way, an
electron transfer leading to the starting material [Fe-
(C5Me5)(CO)2]2. In contrast, nucleophilic attack occurs
specifically when [Fe(C5Me5)(CO)2][K] is treated
with the ortho- or para-chlorobenzoyl chloride o-,p-
ClC6H4C(O)Cl, affording the desired chlorobenzoyl com-
plexes [Fe(C5Me5)(CO)2{C(O)C6H4Cl}] (1b, o-Cl (62%
yield); 1c, p-Cl (79% yield)). The corresponding meth-
oxycarbene complexes [Fe(C5Me5)(CO)2{η1-C(OMe)-
C6H4X}][OTf] (2a -c) (OTf ) OSO2CF3) are then ob-
tained from 1a -c by O-methylation (MeOTf, CH2Cl2,
16 h) according to classical procedures.7 Complex
[Fe(C5Me5)(CO)2{η1-CH(OMe)C6H4-o-OMe}] (3a ) is then
prepared by reduction of the methoxycarbene 2a with
NaBH4 in 9:1 THF-MeOH, the presence of methanol
being essential to obtain specifically 3a in good yield.
Further reduction occurs by using pure THF as solvent,
leading to a mixture of 3a and [Fe(C5Me5)(CO)2{η1-
CH2C6H4-o-OMe}], a feature widely observed.7,8 The
nonheteroatom-substituted anisylcarbene complex [Fe(C5-
Me5)(CO)2{η1-C(H)C6H4-o-OMe}][OTf] (4a ) is thus gen-
erated from 3a by R-methylate abstraction using
Me3SiOTf1,2 (Scheme 1).
singlets at δ 15.61 and 15.28 (dCH) in intensity ratio
20:80, respectively; these signals coalesce at TC (300
MHz) ) -62 °C giving rise to a unique singlet at δ
15.16. Since the rotation around the Fe-CR bond
cannot be frozen out in such complexes, as already
mentioned for related carbene-iron derivatives,7,9 this
feature arises from restricted rotation about the CR-
Cipso bond. Therefore, complex 4a can exist as two
geometric isomers which differ from each other in the
orientation of the anisyl group; the observed ratio
probably results from steric requirements of the ortho-
substituent (barrier to aryl rotation ∆Gq ) 9.7 kcal
mol-1). These results are in agreement with those
described by Brookhart for the parent Cp complex
[Fe(C5H5)(CO)2{η1-C(H)C6H4-p-OMe}][OTf], when a
unique isomer is observed as indicated by a single signal
1
for the carbene hydrogen in the H NMR spectrum at
low temperature; the aromatic protons appear as a set
of four distinct signals assigned to the nonequivalent
o,o′- and m,m′-hydrogens.7a It has been proposed that
the aryl group is aligned with the Fe-CR-Cipso plane
(see the Newman projection in Scheme 2), a conforma-
tion providing better electronic delocalization of the
positive charge.7a,10 Moreover, the 13C resonance at -40
°C (a temperature at which the interconversion is rapid)
for the carbene carbon atom of 4a appears as a typical
low-field singlet at δ 322.6. It is noteworthy that one
CO resonance at δ 210.6 is observed, whereas for the
methoxycarbene complexes 2a ,b the 13C NMR (CDCl3,
25 °C) spectra show that the two carbonyl ligands are
magnetically nonequivalent. In contrast, the CO ligands
of the parent para-substituted complex [Fe(C5Me5)(CO)2-
{η1-C(OMe)C6H4-p-Cl}][OTf] (2c) also give rise to a
unique singlet (13C (CDCl3): δCO 210.9). These data
suggest that the conformation is different for each type
of carbene complex, but we cannot definitely assign the
carbene orientation.7a,11 In the case of the methoxycar-
bene complexes 2, the resonance stabilization provided
by the better π-bonding methoxy carbene substituent
would be substantial, compared with that of the aro-
matic ring, and moreover, steric interactions can also
govern the carbene conformation, especially in the
NMR Stu d ies a n d Con for m a tion a l An a lysis. All
1
the new complexes 2a -c exhibit H and 13C resonance
patterns characteristic of the methoxycarbene ligand
(Table 1).1,2,7 The nonheteroatom-stabilized carbene
complex [Fe(C5Me5)(CO)2{η1-C(H)C6H4-o-OMe}][OTf] (4a)
1
was directly generated in an NMR tube. The H NMR
spectrum (CD2Cl2) shows at -80 °C two low-field
(4) (a) Arndtsen, B. A.; Bergman, R. G. Science 1995, 270, 1970 and
references cited. (b) Winter, C. H.; Arif, A. M.; Gladysz, J . A. J . Am.
Chem. Soc. 1987, 109, 7560. (c) Peng, T.-S.; Winter, C. H.; Gladysz, J .
A. Inorg. Chem. 1994, 33, 2534. (d) Czech, P. T.; Gladysz, J . A.; Fenske,
R. F. Organometallics 1989, 8, 1806. (e) Burk, M. J .; Crabtree, R. H.;
Holt, E. M. Organometallics 1984, 3, 638.
(5) Anhydrides or aldehydes have been also used: (a) Ru¨ck-Braun,
K.; Ku¨hn, J . Synlett 1995, 11, 1194. (b) Vargas, R. M.; Theys, R. D.;
Hossain, M. M. J . Am. Chem. Soc. 1992, 114, 777.
(6) (a) Hunter, A. D.; Szigety, A. B. Organometallics 1989, 8, 2670.
(b) Magdesieva, T. V.; Kukhareva, I. I.; Artamkina, G. A.; Butin, K.
P.; Beletskaya, I. P. J . Organomet. Chem. 1994, 468, 213.
(7) (a) Brookhart, M.; Studabaker, W. B.; Humphrey, M. B.; Husk,
G. R. Organometallics 1989, 8, 132. (b) Brookhart, M.; Tucker, J . R.;
Husk, G. R. J . Am. Chem. Soc. 1983, 105, 258. (c) Casey, C. P.; Miles,
W. H.; Tukada, H. J . Am. Chem. Soc. 1985, 107, 2924. (d) Cutler, A.
R. J . Am. Chem. Soc. 1979, 101, 604. (e) Nlate, S; Guerchais, V;
Lapinte, C. J . Organomet. Chem. 1992, 434, 89.
(9) Guerchais, V.; Lapinte, C.; The´pot, J .-Y.; Toupet, L. Organome-
tallics 1988, 7, 604.
(10) Schilling, B. E. R.; Hoffmann, R.; Lichtenberger, D. L. J . Am.
Chem. Soc. 1979, 101, 585.
(11) Knors, C.; Kuo, G.-H.; Lauher, J . W.; Eigenbrot, C.; Helquist,
P. Organometallics 1987, 6, 988.
(8) Davison, A.; Reger, D. L. J . Am. Chem. Soc. 1972, 94, 9237.

126 Organometallics, Vol. 16, No. 1, 1997
Ta ble 1. Selected 13C NMR (CDCl3, δ in p p m ver su s TMS, 25 °C) Da ta
Poignant et al.
cationic carbene complexes [Fe(C5Me5)(CO)n{ηx-C(OMe)C6H4X}]+
(x ) 1, n ) 2; x ) 2, n ) 1) (a , X ) o-OMe; b, X ) o-Cl; c, X ) p-Cl)
neutral carbene complexes
[Fe(C5Me5)(CO)(X′){η1-C(OMe)C6H4-o-X)]
complex
dC
CO
ArX
Aripso
complex
X′
dC
CO
ArX
Aripso
4a a
2a
2b
2c
5a
5b
322.6
328.2
323.5
326.0
325.8
329.1
210.6
159.5 (br s)
148.9
122.8
147.3
167.7
144.0
138.8
147.4
138.1
134.8
145.5
6a b
6b
7a
8
I
I
Cl
334.9
328.1
335.1
311.1
221.6
220.2
218.7
214.6
149.9
124.6
149.5
187.0
141.8
149.4
141.9
139.4
210.9, 210.6
210.7, 210.2
210.9
213.1
211.5
X ) X′ ) O
144.9
a
b
[Fe(C5Me5)(CO)2{)C(H)C6H4-o-OMe}][OTf] (-40 °C). C6D6.
Sch em e 2
Sch em e 3
F igu r e 1. Molecular structure of [Fe(C5Me5)(CO){η2-
C(OMe)C6H4-o-Cl}][OTf] (5b) showing the atom-labeling
scheme.
decomposition. The monodecarbonylation/chelation re-
action is easily monitored by IR spectroscopy, the two
initial ν(CtO) absorptions being replaced by a new
absorption at 1977 (5a ) or 1990 (5b) cm-1. The differ-
ence in the spectra of the unchelated complex 2b and
the chelated one 5b comes, in particular, from the 13C
NMR signal of the ArCl carbon; the resonance is shifted
downfield from δ 122.8 to 144.9, respectively. The
chlorine atom, like the oxygen atom in 5a , acts as a
neutral 2e- donor ligand (Lewis acid-base interaction)
allowing the formation of a five-membered metalla-
cycle.12
The structure of the complex 5b was unequivocally
established by an X-ray crystal structure analysis.
Figure 1 shows the molecular structure of complex 5b;
selected bond distances and angles are given in Table
2, and positional parameters, in the Supporting Infor-
mation. The environment about the iron atom corre-
sponds to that of a slightly distorted three-legged piano
stool: in the metallacycle, the ring angle at the iron
center is reduced to 84.7(2)° (C(10)-Fe-Cl); the other
angles C(101)-Fe-C(10) and C(101)-Fe-Cl are 95.8(3)
and 100.0(2)°, respectively. The Fe-CR distance of
1.857(6) Å is similar to the Fe-carbene distance found
for the related (dppe)-substituted methoxycarbene com-
C5Me5 series. We have previously shown that the
secondary methoxycarbene complex [Fe(C5Me5)(CO)2-
{dCH(OMe)}][PF ] is generated at -80 °C as a C O
‚‚
6
cis isomer (in which the methoxy substituent is directed
toward the [Fe(C5Me5)(CO)2] fragment); subsequent
irreversible isomerization gives the thermodynamic
trans form,9 a feature not observed for the related Cp
complex.7d
Neu tr a l a n d Ca tion ic Ch ela te Ca r ben e Com -
p lexes. The cationic (η2-C,X) chelate-carbene com-
plexes [Fe(C5Me5)(CO){η2-C(OMe)C6H4-o-X}][OTf] (5a,b)
are formed from 2a ,b by irradiation in CH2Cl2 (visible
light, overnight) (Scheme 3). Both compounds 5a ,b are
isolated as black crystals in good yields by crystalliza-
tion from a CH2Cl2/Et2O mixture; they can be stored
indefinitely under argon in the solid state without
(12) Related chelated metal-carbenes: (a) Klemarczyk, P.; Price,
T.; Priester, W.; Rosenblum, M. J . Organomet. Chem. 1977, 139, C25.
(b) Lennon, P.; Priester, W.; Rosan, A. M.; Madhavarao, M.; Rosenblum,
M. J . Organomet. Chem. 1977, 139, C29. (c) Do¨tz, K. H. Organome-
tallics in Organic Synthesis; de Meijere, A., tom Dieck, H., Eds.;
Springer-Verlag: Berlin, Heidelberg, 1987; p 85. (d) Do¨tz, K. H.; Larbig,
H.; Harms, K. Chem. Ber. 1992, 125, 2143.

Arylcarbene Complexes
Organometallics, Vol. 16, No. 1, 1997 127
Ta ble 2. Selected Bon d Len gth s a n d An gles for 5b
Sch em e 5
Bond Lengths (Å)
Fe(1)-Cl(1)
Fe(1)-C(10)
Fe(1)-C(101)
2.310(2)
1.857(6)
1.766(8)
C(10)-C(11)
Cl(1)-C(12)
C(10)-O(10)
1.493(9)
1.753(7)
1.304(7)
Bond Angles (deg)
C(101)-Fe(1)-C(10) 95.8(3) C(12)-Cl(1)-Fe(1)
96.9(2)
C(10)-Fe(1)-Cl(1)
84.7(2) O(101)-C(101)-Fe(1) 174.0(7)
C(101)-Fe(1)-Cl(1) 100.0(2) O(10)-C(10)-C(11)
108.3(6)
Sch em e 4
plex [Fe(C5Me5)(η2-PPh2CH2CH2PPh2){dC(OMe)H}]-
[PF6] (1.82(2) Å).13-15 The Fe-Cl bond (2.310(2) Å) is
comparable to that of the terminal chloride complex
[Fe(C5Me4Et)(CO)2(Cl)] (2.304(2) Å).16 The Cl-CAr bond
distance (1.753(7) Å) is slightly shorter than that of the
Related neutral carbene complexes have been previ-
ously prepared by different procedures. Winter reported
that the complexes [M(C5H5)(CO)(I){dC(OEt)Ph}] (M )
Fe, Ru) are accessible from the tin derivatives [M(C5H5)-
(CO)(SnPh3)(dC(OEt)Ph)] by treatment with iodine.15
An original route, recently described by Werner, consists
of reacting the acetato-ruthenium complex [Ru(C5H5)-
(PPh3)(η2-O2CMe)] with diaryldiazomethanes; subse-
quent addition of Et3NHCl leads to the formation of [Ru-
(C5H5)(PPh3)(Cl)(dCArAr′)].18
chelate chloroarene complex [MePt{η2-Ph2P(C6H4-o-Cl}-
{η1-Ph2P(C6H4-o-Cl}][BF4]17 (chelated Cl-CAr: 1.788(5)
Å).
The chelate-carbene complexes 5a ,b react with 1
equiv of [nBu4N][I] to give the neutral carbene com-
plexes [Fe(C5Me5)(CO)(I){η1-C(OMe)C6H4-o-X}] (6a ,b),
the chelated group X being displaced by the halide
(Scheme 3). This reaction is chemospecific, only one
product being formed in good yield. Two pathways
could be a priori considered: the well-established O-
demethylation process of the methoxycarbene substitu-
ent,8 which is observed for the dicarbonyl complexes
2a ,b (the reverse reaction of 1 f 2), or the substitution
reaction allowing access to neutral halogeno carbene
The reactivity of the methoxy-chelate carbene complex
5a toward hydride reagents is highly dependent on the
reaction conditions. The neutral chelate complex
[Fe(C5Me5)(CO){η2-CH(OMe)C6H4-o-OMe}] (9) is formed
upon reduction at -80 °C of 5a by using either NaBH4
in a mixture of 9:1 THF-MeOH or LiBEt3H in pure
THF (Scheme 5). Extraction with pentane gives an
orange-brown powder in 93% yield, the NMR (1H and
13C) spectra of which display one set of signals, assigned
to the presence of one diastereoisomer.19 Formally, the
formation of this latter species arises from an hydride
attack at the electrophilic carbene carbon atom. How-
ever, since in the present case the methoxy group is
labile, it is plausible to suggest that the addition should
initially occur at the iron center. This proposal is
supported by the above results concerning nucleophilic
substitution at the metal center by halides, but we have
not been able to observe any intermediate. Such migra-
tion processes (hydride, alkyl, vinyl, or aryl) have been
extensively proposed for group 8 metal-carbene com-
plexes, but the transient species are quite often not
spectroscopically detected.18,20,21 An alternative route
to 9 is via irradiation (visible light) of the dicarbonyl
complex 3a ; however, the reaction is slow and involves
some decomposition. As we have already noticed in this
complexes. The chelation process is reversible; complex
-
6b reacts with 1 equiv of AgBF4 to regenerate 5b-BF4
.
Analogously, 5a is converted, in the presence of
[(PPh3)2N][Cl], to the parent chloro derivative [Fe(C5-
Me5)(CO)(Cl){η1-C(OMe)C6H4-o-OMe}] (7), but sponta-
neous elimination of MeCl occurs in CDCl3 solution
within several hours to yield the new neutral chelate
carbene complex [Fe(C5Me5)(CO){η2-C(OMe)C6H4-o-O}]
(8) (Scheme 4). This reaction was monitored by 1H and
13C NMR spectroscopy; the OMeAr signal decreases, and
simultaneously, resonances at δ (1H) 3.02 and δ (13C)
25.9 attributed to MeCl appear. The mechanism of the
formation of 8, which results formally from a demeth-
ylation of the o-methoxy group, is still not clear.
(13) Roger, C. Ph.D. Dissertation, University of Rennes, 1989.
(14) For X-ray crystal structures of iron-carbene complexes, see ref
11 and the following: Riley, P. E.; Davies, R. E.; Allison, N. T.; J ones,
W. M. J . Am. Chem. Soc. 1980, 102, 2458. Riley, P. E.; Davies, R. E.;
Allison, N. T.; J ones, W. M. Inorg. Chem. 1982, 21, 1321. Crespi, A.
M.; Shriver, D. F. Organometallics 1985, 4, 1830.
(15) (a) Adams, H.; Bailey, N. A.; Ridgway, C.; Taylor, B. F.; Walters,
S. J .; Winter, M. J . J . Organomet. Chem. 1990, 394, 349. (b) Adams,
H.; Maloney, C. A.; Muir, J . E.; Walters, S. J .; Winter, M. J . J . Chem.
Soc., Chem. Commun. 1995, 1511.
(16) Akita, M.; Terada, M.; Tanaka, M.; Morooka, Y. J . Organomet.
Chem. 1996, 510, 255. See also: Roger, C.; Hamon, P.; Toupet, L.;
Rabaaˆ, H.; Saillard, J .-Y.; Hamon, J .-R.; Lapinte, C. Organometallics
1991, 10, 1045.
(18) Braun, T.; Gevert, O.; Werner, H. J . Am. Chem. Soc. 1995, 117,
7291.
(19) (a) Brookhart, M.; Buck, R. C. J . Am. Chem. Soc. 1989, 111,
559. (b) Lorsbach, B. A.; Bennet, D. M.; Prock, A.; Giering, W. P.
Organometallics 1995, 14, 869 and references cited.
(20) Yang, J .; J ones, W. M.; Dixon, J . K.; Allison, N. T. J . Am. Chem.
Soc. 1995, 117, 9776.
(21) Osborn, V.; Parker, C. A.; Winter, M. J . J . Chem. Soc., Chem.
Commun. 1986, 1185. Adams, H.; Bailey, N. A.; Tattershall, C. E.;
Winter, M. J . Chem. Soc., Chem. Commun. 1991, 912.
(17) Gomes-Carneiro, T. M.; J ackson, R. D.; Downing, J . H.; Orpen,
A. G.; Pringle, P. G. J . Chem. Soc., Chem. Commun. 1991, 317.

128 Organometallics, Vol. 16, No. 1, 1997
Poignant et al.
Sch em e 6
series, cationic species are more robust toward irradia-
tion than the neutral derivatives.22
In contrast, reaction of 5a with NaBH4 in pure THF
does not give the simple hydride addition product 9 but
leads to the formation of the organoborohydride complex
[Fe(C5Me5)(CO){η2-H2BHCH2C6H4-o-OMe}] (10) (Scheme
5). Complex 10 has been fully characterized by IR, mass
and NMR (1H, 13C, 11B) spectra, elemental analysis, and
an X-ray diffraction study.3 A well-resolved spectrum
1
shows a low-field pseudoquartet at δ 6.35 with a J B-H
value of ca. 108 Hz characteristic of a B-H terminal
coupling constant. The two bridging hydrogens appear
at δ -17.87 (pseudoquartet, 1J B-H 43 Hz). Upon boron
decoupling, both pseudoquartets give rise to singlets.
These chemical shifts, as well as that of the boron (δ(11B)
55.33), compare well with those of the dihapto complexes
[(C5H5)2Ta{η2-H2BHSi(t-Bu)2H}] and [(C5H5)2Ta{η2-
BH4}].23,24 Moreover, this assignment is corroborated
by the methylene resonance located at δ 2.60 (dt, 3J H-BH
3
5 Hz, J H-BH 2.5 Hz). Besides the reduction of the
2
dCHOMe fragment into a methylene group (vide supra),
the reaction involves a formal insertion of BH3 into a
Fe-C bond. As suggested for the former reaction, the
hemilabile ligand could promote the formation of a
monodentate borohydride BH4- intermediate; the inser-
tion of BH3 would then occur within the coordination
sphere of the metal. Such a monodentate borohydride
iron complex [FeH(dmpe)2(η1-BH4)] has been reported.25
Sch em e 7
The hemilabile ligand OMeAr in 5a is easily substi-
tuted by neutral nucleophiles such as PMe3 (room
temperature, CH2Cl2) to give the cationic complex
[Fe(C5Me5)(CO)(PMe3){η1-C(OMe)C6H4-o-OMe}][OTf]
(11). Substitution by PMe3 cannot be directly ac-
complished for 2a , due to the competitive electrophilic
attack at the carbene carbon atom. Complex 11 is then
converted via photo-induced decarbonylation into the
phosphine-substituted chelate complex [Fe(C5Me5)-
(PMe3){η2-C(OMe)C6H4-o-OMe}][OTf] (12) (Scheme 6).
In the permethylated-Cp series, complete decarbonyla-
tion always requires UV irradiation.26 Addition of
[nBu4N][I] to 12 quantitatively affords the o-anisyl
complex [Fe(C5Me5)(PMe3)(CO){η1-C6H4-o-OMe}] (13) as
a mixture of two diastereoisomers in 65:35 ratio (Scheme
Irradiation of 2b or 5b in CH3CN (UV light, 5 h) gives
the bis(acetonitrile) complex [Fe(C5Me5)(CH3CN)2{η1-
C(OMe)C6H4-o-Cl}][OTf] (14) (Scheme 7). Due to the
high lability of the CH3CN ligands, compound 14
decomposes in other organic solvents, even in diethyl
ether. Therefore, compound 14 is precipitated in nearly
quantitative yield as a brown powder by addition of
pentane. NMR studies in CD3CN confirm the proposed
structure; the presence of a single C5Me5 signal at δ 1.42
1
6). They are clearly distinguished in the H, 13C, and
31P NMR spectra of 13. This can be explained by the
presence of both the stereogenic iron center and a
hindered Fe-Cipso rotation (assimilated to an atropi-
somerism). The chemoselectivity of the reaction of
iodide toward chelate complexes changes upon substitu-
tion of a carbonyl ligand by PMe3: the electrophilic
character of the metal center is weakened by the
electron-donating phosphine. The competitive deme-
thylation occurs, and decoordination of the OMeAr group
then promotes the deinsertion/migration of the CdO
group.22
1
in the H NMR spectrum of the crude product indicates
the formation a single product, and the ArCl resonance
located at δ 125.2 compares well with that of the
unchelated dicarbonyl complex 2b. Complex 14 reacts
(CH3CN, room temperature) with (diphenylphophino)-
methane (dppm) to give the diphosphine-carbene com-
plex [Fe(C5Me5)(dppm){η1-C(OMe)C6H4-o-Cl}][OTf] (15)
as an orange powder (Scheme 7). The 31P NMR (CDCl3)
spectrum of 15 exhibits an AB system at δ 32.77 and
29.07 (2J P-P 77 Hz); as for the parent dicarbonyl complex
2b, the ancillary ligands are magnetically nonequiva-
lent. For spectroscopic comparison, the mono(acetoni-
trile) derivative [Fe(C5Me5)(CO)(CH3CN){η1-C(OMe)-
(22) Nlate, S.; Lapinte, C.; Guerchais, V. Organometallics 1993, 12,
4657
(23) J iang, Q.; Carroll, P. J .; Berry, D. H. Organometallics 1993,
12, 177.
(24) Ghilardi, C. A.; Innocenti, P.; Midollini, S.; Orlandini, A. J .
Organomet. Chem. 1982, 231, C78.
(25) Baker, M. V.; Field, L. D. J . Chem. Soc., Chem. Commun. 1984,
996. Bau, R.; Yuan, H. S. H.; Baker, M. V.; Field, L. D. Inorg. Chim.
Acta 1986, 114, L27.
(26) Green, M. L. H.; Haggitt, J .; Mehnert, C. P. J . Chem. Soc.,
Chem. Commun. 1995, 1853.

Arylcarbene Complexes
Organometallics, Vol. 16, No. 1, 1997 129
Sch em e 8
There is no precedent for such a reaction for carbene
complexes of a group 8 transition metal, whereas the
metal-carbene bond of complexes of group 6 is easily
cleaved by oxidizing reagents.32 It should be pointed
out that the above reactions differ from that involved
in the formation of the formaldehyde complex [Re(C5H5)-
(NO)(PPh3)(η2-CH2dO)][PF6] reported by Gladysz, ob-
tained by reacting the methylene complex [Re(C5H5)-
(NO)(PPh3)(dCH2)][PF6] with the nucleophilic iodosyl-
benzene.33 On the other hand, the formation of ben-
zophenone has been observed upon photolysis of diphen-
yldiazomethane in the presence of oxygen.34
In summary, despite the entropic effect of the chela-
tion, the ortho-chlorine or methoxy ligand is labile and
the O-demethylation pathway can thus be inhibited.
Convenient routes to various substituted neutral and
cationic iron-carbene complexes have been developed;
consequently, the synthetic utility of which will be
further investigated.
C6H4-o-Cl}][OTf] (16) was prepared; it is readily formed
upon dissolving complex 5b in CH3CN and isolated as
red microcrystals. Proton NMR studies reveal that
complex 16 exists as two CR-Cipso geometric isomers in
a 75:25 ratio at low temperature (TC (300 MHz) ) 22
°C; barrier to aryl rotation ∆Gq ) 14.3 kcal mol-1); they
are particularly well-differentiated in the 13C NMR
spectrum (see Experimental Section). Thus, it is pos-
sible to access to a series of methoxycarbene complexes,
the conformation of which depends on the nature of the
ancillary ligands.
Exp er im en ta l Section
Complex 14 was expected to be a useful precursor to
electron-rich N-heterocyclic-containing iron complexes,
but attempts to substitute the CH3CN ligands by the
chelating 4,4′-tert-butyl-2,2′-bipyridine (bipy*) ligand27
(CH3CN, O °C) results in a mixture of [Fe(bipy*)3]2+ and
the unreacted starting complex 14. This result shows
that substitution of labile ligands in cationic iron
complexes, although very efficient in the cases of
diphosphines, cannot be applied to strong σ-donor N,N-
ligands.28,29
Disp la cem en t of th e Ca r ben e Liga n d . Carbene
transfer from iron complexes to olefins has been exten-
sively developed,1 and high enantioselective cyclopro-
panation has been achieved by using the (R) and (S)
chiral-at-iron complexes [Fe(C5H5)(CO)(PPh2R*){dCH-
(CH3}]+.30 To the best of our knowledge the displace-
ment of the carbene ligand as a carbonyl organic
substrate, such as aldehyde or ester, has not been
investigated. The electrophilic anisylcarbene complex
4a , generated in situ at -80 °C in CH2Cl2, reacts with
molecular dioxygen (bubbling for 30 s) to give the
o-anisaldehyde o-MeOC6H4CHO and the triflate deriva-
tive [Fe(C5Me5)(CO)2(OTf)]31 (Scheme 8). These two
compounds are readily separated in quantitative yield
by extraction with pentane and ether, respectively. In
contrast, the related dicarbonyl methoxycarbene com-
plex 2b is inert toward O2; the starting complex is
recovered even after 2 days of reaction. The nature of
the ancillary ligands dramatically influences the release
of carbene. Thus, the bis(acetonitrile) complex 14 reacts
with O2 to give o-ClC6H4C(O)OMe (Scheme 8) whereas
the neutral iodo carbene complex 6b remains intact in
solution in DMSO over several days.
Gen er a l Da ta . All manipulations were carried out under
an argon atmosphere with Schlenk or glovebox techniques.
Solvents were dried and distilled under nitrogen before use
by standard methods. Photolysis experiments were carried
out by using an Original Hanau 150 W (Hg, high pressure)
lamp; visible irradiation reactions were performed using a
glass vessel whereas a quartz tube was used for near-UV
irradiation. NMR spectra (1H, 300 MHz; 13C, 75.47 MHz; 31P,
121.5 MHz; 11B, 96.295 MHz) were recorded on Bruker WP-
80 or AC 3000 spectrometers by S. Sinbandhit (CRMPO,
Universite´ de Rennes 1). Infrared spectra were obtained with
a Nicolet 205 FT-IR spectrometer. Mass spectra were recorded
on a Varian MAT 311 (70 eV) instrument at the CRMPO.
Microanalyses were performed by the “Centre de Microanalyse
du CNRS” at Vernaison, France.
P r ep a r a tion of [F e(C5Me5)(CO)2{C(O)C6H4-X}] (1: a , X
) o-OMe; b, X ) o-Cl; c, X ) p-Cl). Gen er a l P r oced u r e. A
suspension of 6 mmol (3 g) of [Fe(C5Me5)(CO)2]2 and 12 mmol
(468 mg) of potassium in 20 mL of THF was refluxed for 2 h.
To the resulting orange mixture was added at room temper-
ature 12 mmol of the appropriate acid chloride XC6H4C(O)Cl.
The solution was stirred for 30 min, and the solvent was
removed in vacuo. Compound 1 was extracted with ether (3
× 20 mL); chromatography on alumina (eluant pentane/
ether: 80/20) afforded a yellow crystalline solid.
3
1a (80% yield): 1H NMR (CDCl3) δ 7.13 (dt, J H-H 8 Hz,
3
4
4J H-H 1.7 Hz, 1H, Ar), 6.86 (dt, J H-H 7 Hz, J H-H 0.9 Hz, 1H,
3
3
4
Ar), 6.81 (d, J H-H 8 Hz, 1H, Ar), 6.65 (dd, J H-H 7 Hz, J H-H
1.7 Hz, 1H, Ar), 3.78 (s, 3H, OMe), 1.83 (s, 15H, C5Me5); 13C-
{1H} NMR (CDCl3) δ 263.9 (CdO), 215.9 (CO), 151.2 (Aripso),
147.8 (ArOMe), 127.7 (Ar), 120.9 (Ar), 120.3 (Ar), 110.9 (Ar),
97.7 (C5Me5), 55.1 (OMe), 9.6 (C5Me5); IR (CH2Cl2) 1613 (s,
ν
CdO), 1943 (s, νCO), 2000 (s, νCO). Anal. Calcd for C20H22O4-
Fe: C, 62.85; H, 5.80. Found: C, 62.56; H, 5.73.
3
1b (62% yield): 1H NMR (CDCl3) δ 7.23 (dd, J H-H 7.2 Hz,
4J H-H 1.2 Hz, 1H, Ar), 7.19 (td, J H-H 7.4 Hz, J H-H 1.3 Hz,
3
4
3
4
1H, Ar), 7.08 (td, J H-H 7.6 Hz, J H-H 1.7 Hz, 1H, Ar), 6.78
(dd, 3J H-H 7.5 Hz, 4J H-H 1.7 Hz, 1H, Ar), 1.85 (s, 15H, C5Me5);
13C{1H} NMR (CDCl3) δ 262.4 (CdO), 215.6 (CO), 155.4 (Aripso),
129.5 (Ar), 127.5 (Ar), 126.8 (Ar), 124.1 (ArCl), 122.2 (Ar), 98.2
(C5Me5), 9.5 (C5Me5); IR (CH2Cl2) 1610 (s, νCdO), 1947 (s, νCO),
(27) Ben Hadda, T.; Le Bozec, H. Inorg. Chim. Acta 1993, 204, 103.
(28) Cationic [Ru(C5Me5)(2,2′-bipy)(L)]+ complexes have been de-
scribed: Balavoine, G. G. A.; Boyer, T.; Livage, C. Organometallics
1992, 11, 456.
(29) The bipy*-substituted carbonyl complex [Fe(C5Me5)(η2-
bipy*)(CO)]+ is thermally stable: Poignant, G.; Guerchais, V. Work in
progress.
(30) (a) Brookhart, M.; Timmers, D.; Tucker, J . R.; Williams, G. D.;
Husk, G. R.; Brunner, H.; Hammer, B. J . Am. Chem. Soc. 1983, 105,
6721. (b) Brookhart, M.; Liu, Y.; Goldman, E. W.; Timmers, D. A.;
Williams, G. D. J . Am. Chem. Soc. 1991, 113, 927.
(31) (a) Guerchais, V.; Astruc, D.; Nunn, C. M.; Cowley, A. H.
Organometallics 1990, 9, 1036. (b) Humphrey, M. B.; Lamanna, W.
M.; Brookhart, M.; Husk, G. R. Inorg. Chem. 1983, 22, 3355.
(32) (a) Fischer, E. O.; Riedmuller, S. Chem. Ber. 1974, 107, 915.
(b) Casey, C. P.; Boggs, R. A.; Anderson, R. L. J . Am. Chem. Soc. 1972,
94, 8947.
(33) Buhro, W. E.; Georgiou, S.; Fernandez, J . M.; Patton, A. T.;
Strouse, C. E.; Gladysz, J . A. Organometallics 1986, 5, 956.
(34) Kirmse, W. Carbene Chemistry. In Organic Chemistry; Aca-
demic Press: New York, 1971; Vol. 1.

130 Organometallics, Vol. 16, No. 1, 1997
Poignant et al.
2003 (s, νCO). Anal. Calcd for C19H19O3ClFe: C, 59.02; H, 4.95.
Found: C, 59.03; H, 5.03.
1c (79% yield): 1H NMR (CDCl3) δ 7.36 (m, AA′BB′, 4H,
Ar), 1.79 (s, 15H, C5Me5); 13C{1H} NMR (CDCl3) δ 262.0 (CdO),
216.0 (CO), 147.7 (Aripso), 136.0 (ArCl), 128.1 (Ar), 127.5 (Ar),
97.4 (C5Me5), 9.7 (C5Me5); IR (CH2Cl2) 1601 (s, νCdO), 1943 (s,
Then 0.56 mmol (110 µL) of Me3SiOSO2CF3 was added: 1H
NMR (CDCl3, 20 °C) δ 15.42 (s, 1H, dCH), 7.96 (m, 1H, Ar),
7.77 (m, 1H, Ar), 7.16 (m, 2H, Ar), 4.15 (s, 3H, OMeAr), 2.00
(s, 15H, C5Me5); 13C{1H} NMR (CDCl3, -40 °C) δ 322.6 (dCH),
210.6 (CO), 159.5 (br s, ArOMe), 145.7 (Ar), 144.0 (Aripso), 137.6
(Ar), 122.0 (Ar), 113.4 (Ar), 105.7 (C5Me5), 56.7 (OMeAr), 10.1
(C5Me5); 1H NMR (CD2Cl2, -80 °C) δ 15.61 (br s, 0.2H, dCHb),
15.07 (br s, 0.8H, dCHa), 7.99 (m, 1H, Ar), 7.59 (m, 1H, Ar),
7.22 (m, 2H, Ar), 4.21 (s, 3H, OMeAr), 1.98 (s, 15H, C5Me5); TC
(300 MHz) ) -62 °C; δ (-50 °C) 15.16 (br s, 1H, dCH); IR
(CH2Cl2) 2045 (s, νCO), 1995 (s, νCO).
ν
CO), 2003 (s, νCO). Anal. Calcd for C19H19O3ClFe: C, 59.02;
H, 4.95. Found: C, 58.96; H, 5.06.
P r ep a r a t ion of [F e(C5Me5)(CO)2{η1-C(OMe)C6H4X}]-
[CF 3SO3] (2: a , X ) o-OMe; b, X ) o-Cl; c, X ) p-Cl). A
CH2Cl2 solution (20 mL) of 2.5 mmol of 1 was treated with 2.5
mmol (282 µL) of CH3OSO2CF3. The mixture was stirred
overnight, and the solution was then reduced in volume under
vacuum to ca. 3-5 mL. Compound 2 was precipitated by
addition of diethyl ether giving yellow microcrystals.
2a (98% yield): 1H NMR (CDCl3) δ 7.42, 7.12, 7.00, 6.82 (4
× m, 4H, Ar), 4.41 (s, 3H, OMe), 3.88 (s, 3H, OMeAr), 1.92 (s,
15H, C5Me5); 13C{1H} NMR (CDCl3) δ 328.2 (dC), 210.9 (CO),
210.6 (CO), 148.9 (ArOMe), 138.8 (Aripso), 132.6 (Ar), 121.7 (Ar),
121.5 (Ar), 111.7 (Ar), 102.2 (C5Me5), 70.2 (OMe), 55.9 (OMeAr),
9.7 (C5Me5); IR (CH2Cl2) 2004 (s, νCO), 2047 (s, νCO). Anal.
Calcd for C22H25O7FeSF3: C, 48.37; H, 4.61. Found: C, 48.44;
H, 4.70.
P r ep a r a tion of [F e(C5Me5)(CO){η2-C(OMe)C6H4-o-X}]-
[CF 3SO3] (5: a , X ) OMe; b, X ) Cl). In a Schlenk tube, a
CH2Cl2 solution (10 mL) of 1 mmol (547 mg) of 2a or 2b was
irradiated overnight. After removal of the solvent under
vacuum, the solid was washed with ether, and crystallization
from CH2Cl2/Et2O gave brown crystals.
5a (96% yield): 1H NMR (CDCl3) δ 7.65 (m, Ar), 7.43 (d,
Ar), 7.21 (m, Ar), 4.78 (s, 3H, OMe), 3.95 (s, 3H, OMeAr), 1.61
(s, 15H, C5Me5); 13C{1H} NMR (CDCl3) δ 325.8 (dC), 213.1
(CO), 167.7 (ArOMe), 137.2 (Ar), 134.8 (Aripso), 125.0 (Ar), 118.9
(Ar), 115.9 (Ar), 95.0 (C5Me5), 71.4 (OMe), 69.9 (OMeAr), 9.5
(C5Me5); IR (Nujol) 1977 (s, νCO). Anal. Calcd for C21H25O6-
FeSF3: C, 48.66; H, 4.86. Found: C, 48.70; H, 4.80.
2b (88% yield): 1H NMR (CDCl3) δ 7.50, 7.42 (2 × m, 3H,
3
4
Ar), 7.19 (dd, J H-H 7.3 Hz, J H-H 1 Hz, 1H, Ar), 4.44 (s, 3H,
OMe), 1.95 (s, 15H, C5Me5); 13C{1H} NMR (CDCl3) δ 323.5
(dC), 210.7 (CO), 210.2 (CO), 147.4 (Aripso), 131.6 (Ar), 129.9
(Ar), 128.6 (Ar), 122.8 (ArCl), 122.7 (Ar), 102.8 (C5Me5), 70.7
(OMe), 9.6 (C5Me5); IR (CH2Cl2) 2009 (s, νCO), 2051 (s, νCO).
Anal. Calcd for C21H22O6ClFeSF3: C, 45.80; H, 4.03. Found:
C, 45.90; H, 4.08.
3
5b (70% yield): 1H NMR (CDCl3) δ 7.95 (dd, J H-H 7.8 Hz,
3
4
4J H-H 1.5 Hz, 1H, Ar), 7.86 (dd, J H-H 8.2 Hz, J H-H 0.8 Hz,
3
4
1H, Ar), 7.75 (td, J H-H 7.8 Hz, J H-H 1.6 Hz, 1H, Ar), 7.57
(td, 3J H-H 7.6 Hz, 4J H-H 1 Hz, 1H, Ar), 4.96 (s, 3H, OMe), 1.67
(s, 15H, C5Me5); 13C{1H} NMR (CDCl3) δ 329.1 (dC), 211.5
(CO), 145.5 (Aripso), 144.9 (ArCl), 136.3 (Ar), 129.4 (Ar), 127.2
(Ar), 122.9 (Ar), 95.7 (C5Me5), 70.7 (OMe), 9.6 (C5Me5); IR
(CH2Cl2) 1990 (s, νCO). Anal. Calcd for C20H22O5ClFeSF3: C,
45.95; H, 4.24. Found: C, 45.74; H, 4.35.
3
2c (55% yield): 1H NMR (CDCl3) δ 7.50 (d, J H-H 8.5 Hz,
2H, Ar), 7.19 (d, 3J H-H 8.5 Hz, 2H, Ar), 4.52 (s, 3H, OMe), 1.90
(s, 15H, C5Me5); 13C{1H} NMR (CDCl3) δ 326.0 (dC), 210.9
(CO), 147.3 (Aripso), 138.1 (ArCl), 129.6 (Ar), 123.5 (Ar), 102.4
(C5Me5), 71.1 (OMe), 9.7 (C5Me5); IR (CH2Cl2) 2004 (s, νCO),
2048 (s, νCO). Anal. Calcd for C21H22O6ClFeSF3: C, 45.80; H,
4.03. Found: C, 45.59; H, 4.01.
P r ep a r a t ion of [F e(C5Me5)(CO)(I){η1-C(OMe)C6H 4-o-
X}][CF 3SO3] (6: a , X ) OMe; b, X ) Cl). A CH2Cl2 solution
(10 mL) of 1 mmol of 5a or 5b was treated with 1.2 mmol (443
mg) of [nBu4N][I]. After removal of the solvent under vacuum,
the solid was extracted with ether. Crystallization from Et2O
gave black crystals.
P r ep a r a tion of [F e(C5Me5)(CO)2{η1-CH(OMe)C6H4-o-
OMe}] (3a ). To 0.8 mmol (454 mg) of 2a and 1.2 mmol (46
mg) of NaBH4 was added 20 mL of THF/MeOH (9:1) at -80
°C. The reaction mixture was stirred at -80 °C for 30 min
and then allowed to warm to room temperature. The solvent
was removed in vacuo, and the residue was extracted with
pentane (2 × 15 mL). Concentration of the solution afforded
245 mg (74%) of orange microcrystals: 1H NMR (C6D6) δ 7.84
3
6a (85% yield): 1H NMR (C6D6) δ 7.89 (d, J H-H 7 Hz, 1H,
3
3
o-Ar), 6.93 (t, J H-H 7 Hz, 1H, p-Ar), 6.72 (t, J H-H 7 Hz, 1H,
3
m-Ar), 6.36 (d, J H-H 8 Hz, 1H, m-Ar), 3.48 (s, 3H, OMe), 3.17
(s, 3H, OMeAr), 1.72 (s, 15H, C5Me5); 1H NMR (DMSO) δ 7.89
3
3
(t, J H-H 7.7 Hz, 1H, Ar), 7.20 (d, J H-H 7.2 Hz, 1H, Ar), 7.06
3
3
(d, J H-H 8.4 Hz, 1H, Ar), 6.91 (t, J H-H 7.7 Hz, 1H, Ar), 3.97
(s, 3H, OMe), 3.80 (s, 3H, OMeAr), 1.73 (s, 15H, C5Me5); 13C{1H}
NMR (C6D6) δ 334.9 (dC), 221.6 (CO), 149.9 (ArOMe), 141.8
(Aripso), 129.4 (Ar) (one Ar signal is obscured by C6D6), 121.4
(Ar), 110.3 (Ar), 97.3 (C5Me5), 63.5 (OMe), 54.6 (OMeAr), 10.5
(C5Me5); IR (Nujol) 1930 (s, νCO). Anal. Calcd for C20H25O3-
FeI: C, 48.42; H, 5.08. Found: C, 48.80; H, 5.04.
3
4
(dd, J H-H 7 Hz, J H-H 2 Hz, 1H, Ar), 7.02 (m, 2H, Ar), 6.64
(dd, 3J H-H 7 Hz, 4J H-H 2 Hz, 1H, Ar), 5.45 (s, 1H, CH), 3.52 (s,
3H, OMe), 3.25 (s, 3H, OMeAr), 1.60 (s, 15H, C5Me5); 13C{1H}
NMR (C6D6) δ 219.3 (CO), 218.1 (CO), 152.8 (ArOMe), 142.6
(Aripso), 124.7 (Ar), 124.5 (Ar), 121.4 (Ar), 109.8 (Ar), 95.8
(C5Me5), 79.8 (CH), 60.5 (OMe), 54.4 (OMeAr), 9.3 (C5Me5); IR
(pentane) 1996 (s, νCO), 1945 (s, νCO). Anal. Calcd for C21H26O4-
Fe: C, 63.33; H, 6.58. Found: C, 63.05; H, 6.65.
6b (68% yield): 1H NMR (CDCl3) δ 7.66 (m, 1H, Ar), 7.33
(m, 1H, Ar), 7.20 (m, 2H, Ar), 4.02 (s, 3H, OMe), 1.84 (s, 15H,
C5Me5); 13C{1H} NMR (CDCl3) δ 328.1 (dC), 220.2 (CO), 149.4
(Aripso), 129.3 (Ar), 129.1 (Ar), 128.2 (Ar), 126.8 (Ar), 124.6
(ArCl), 98.2 (C5Me5), 64.4 (OMe), 10.4 (C5Me5); IR (CH2Cl2) 1952
(s, νCO). Anal. Calcd for C19H22O2ClFeI: C, 45.59; H, 4.43.
Found: C, 45.95; H, 4.67.
Rea ction of [F e(C5Me5)(CO)2{η1-C(OMe)C6H4-o-OMe}]-
[CF 3SO3] (2a ) w ith Na BH4 in THF . To 0.8 mmol (454 mg)
of 2a and 1.2 mmol (46 mg) of NaBH4 was added 20 mL of
THF at -80 °C. The reaction was stirred at -80 °C for 30
min and then allowed to warm to room temperature. The
solvent was removed in vacuo, and the residue was extracted
with pentane (2 × 15 mL). Concentration of the solution
afforded a mixture of 3a and [Fe(C5Me5)(CO)2{η1-CH2C6H4-o-
OMe}], the ratio of which depends on the experiment. Data
for [Fe(C5Me5)(CO)2{η1-CH2C6H4-o-OMe}]: 1H NMR (C6D6) δ
P r ep a r a tion of [F e(C5Me5)(CO)(Cl){η1-C(OMe)C6H4-o-
OMe}] (7) a n d [F e(C5Me5)(CO){η2-C(OMe)C6H4-o-O}] (8).
To a methylene chloride solution of 1 mmol (518 mg) of 5a
was added 1.2 mmol (688 mg) of [(PPh3)2N][Cl] at -80 °C. The
reaction mixture was allowed to warm to room temperature
while stirring, and the solvent was then removed in vacuo.
The resulting solid was extracted with ether, and red micro-
crystals (344 mg, 85%) crystallized at -20 °C. Complex 7 in
CDCl3 solution turned into 8 and MeCl.
[F e(C5Me5)(CO)(Cl){η1-C(OMe)C6H4-o-OMe}] (7). Data
are as follows: 1H NMR (CDCl3) δ 7.25 (m, Ar), 6.97 (m, Ar),
6.88 (m, Ar), 4.13 (s, 3H, OMe), 3.81 (s, 3H, OMeAr), 1.60 (s,
15H, C5Me5); 13C{1H} NMR (CDCl3) δ 335.1 (dC), 218.7 (CO),
3
3
7.47 (d, J H-H 7 Hz, 1H, Ar), 6.96 (m, 2H, Ar), 6.64 (dd, J H-H
7 Hz, 1H, Ar), 3.58 (s, 3H, OMeAr), 2.41 (s, 2H, CH2), 1.46 (s,
15H, C5Me5); 13C{1H} NMR (C6D6) δ 219.1 (CO), 155.8 (ArOMe),
143.1 (Aripso), 128.6 (Ar), 124.1 (Ar), 120.8 (Ar), 109.9 (Ar), 94.7
(C5Me5), 54.5 (OMeAr), 10.0 (CH2), 9.2 (C5Me5).
Gen er a tion of [F e(C5Me5)(CO)2{η1-CH(C6H4-o-OMe)}]-
[CF 3SO3] (4a ). An NMR tube was charged with a CDCl3
solution of 0.38 mmol (150 mg) of 3a and cooled to -80 °C.

Arylcarbene Complexes
Organometallics, Vol. 16, No. 1, 1997 131
149.5 (ArOMe), 141.9 (Aripso), 129.4 (Ar), 123.7 (Ar), 121.1 (Ar),
110.1 (Ar), 98.1 (C5Me5), 64.5 (OMe), 55.3 (OMeAr), 9.6 (C5Me5);
IR (Nujol) 1930 (s, νCO).
31P{1H} NMR (CDCl3/H3PO4 external) δ 31.0 (s, PMe3); IR
(Nujol) 1955 (s, νCO). Anal. Calcd for C24H34O6FePSF3: C,
48.50; H, 5.77. Found: C, 48.22; H, 5.77.
[F e(C5Me5)(CO){η2-C(OMe)C6H4-o-O}] (8). Data are as
follows: 1H NMR (CDCl3) δ 7.26 (d, 3J H-H 7 Hz, 1H, o-Ar), 7.10
P r ep a r a tion of [F e(C5Me5)(P Me3){η2-C(OMe)C6H4-o-
OMe}][CF 3SO3] (12). UV irradiation of 1 mmol (595 mg) of
11 in 210 mL of CH2Cl2 was performed for 90 min. The initial
orange color turned yellow-green. The solvent was removed,
and the resulting solid was crystallized from a CH2Cl2/ether
mixture affording 538 mg (95%) of yellow microcrystals. 1H
3
3
(t, J H-H 7 Hz, 1H, p-Ar), 6.75 (d, J H-H 8 Hz, 1H, m-Ar), 6.37
(t, 3J H-H 8 Hz, 1H, m-Ar), 4.44 (s, 3H, OMe), 3.02 (s, 3H, MeCl),
1.62 (s, 15H, C5Me5); 13C{1H} NMR (CDCl3) δ 311.1 (dC), 214.6
(CO), 187.0 (ArO), 139.4 (Aripso), 134.7 (Ar), 119.4 (Ar), 118.7
(Ar), 113.2 (Ar), 93.8 (C5Me5), 65.7 (OMe), 25.9 (MeCl), 9.4
(C5Me5); IR (Nujol) 1931 (s, νCO). Anal. Calcd for C19H22O3Fe:
C, 64.42; H, 6.26. Found: C, 64.39; H, 6.16.
3
3
NMR (CD2Cl2) δ 7.98 (d, J H-H 8 Hz, 1H, Ar), 7.48 (t, J H-H
8
3
3
Hz, 1H, Ar), 7.08 (t, J H-H 8 Hz, 1H, Ar), 6.85 (d, J H-H 8 Hz,
1H, Ar), 4.65 (s, 3H, OMe), 3.70 (s, 3H, OMeAr), 1.41 (s, 15H,
C5Me5), 1.35 (d, 2J H-H 8 Hz, 9H, PMe3); 13C{1H} NMR (CD2Cl2)
δ 315.1 (d, 2J P-C 25 Hz, dC), 164.6 (ArOMe), 135.3 (Aripso), 132.6
(Ar), 123.9 (Ar), 117.3 (Ar), 111.8 (Ar), 87.9 (C5Me5), 69.3
(OMe), 63.9 (OMeAr), 18.6 (d, 1J P-C 26 Hz, PMe3), 10.4 (C5Me5);
31P{1H} NMR (CD2Cl2/H3PO4 external) δ 24.8 (s, PMe3). Anal.
Calcd for C23H34O5FePSF3: C, 48.77; H, 6.05. Found: C, 48.38;
H, 5.93.
P r ep a r a t ion of [F e(C5Me5)(CO){η2-CH (OMe)C6H 4-o-
OMe}] (9). To a suspension of 1 mmol (518 mg) of 5a in 15
mL of a mixture of 9:1 THF-MeOH, previously cooled to -80
°C, was added 1 mmol (38 mg) of NaBH4 or 1 mmol (1 mL, 1
M solution in THF) of LiBEt3H by using pure THF as solvent.
The solution was then allowed to warm to room temperature.
The initial brown color turned into yellow-orange at -30 °C.
The solvent was evaporated to dryness, and the residue was
extracted with pentane (2 × 10 mL). Cooling the resulting
solution at -20 °C gave 344 mg (93%) of 9 as orange-brown
microcrystals: 1H NMR (C6D6) δ 6.85 (m, 1H, Ar), 6.43 (m,
Rea ction of 12 w ith [n Bu 4N][I]. P r ep a r a tion of [F e-
(C5Me5)(P Me3)(CO){η1-C6H4-o-OMe}] (13). According to the
procedure described for the preparation of 6a ,b, workup gave
362 mg (90% yield) of 13 as a yellow powder. NMR data
showed the presence of two isomers in a 65:35 ratio. Anal.
Calcd for C21H31O2FeP: C, 62.70; H, 7.77. Found: C, 62.51;
H, 7.68.
3
2H, Ar), 5.99 (d, J H-H 6 Hz, 1H, Ar), 4.35 (s, 1H, CH), 3.25
(br s, 6H, OMe and OMeAr), 1.37 (s, 15H, C5Me5); 13C{1H} NMR
(C6D6) δ 224.3 (CO), 158.5 (Ar), one Ar signal is obscured by
C6D6, 125.6 (Ar), 123.2 (Ar), 102.4 (Ar), 93.6 (Ar), 87.7 (C5Me5),
69.6 (CH), 58.1 (OMe), 54.2 (OMeAr), 8.8 (C5Me5); IR (pentane)
1929 (s, νCO). Anal. Calcd for C20H26O3Fe: C, 64.88; H, 7.08.
Found: C, 64.33; H, 7.05.
1
3
Ma jor isom er : H NMR (C6D6) δ 8.00 (m, J H-H 7 Hz, 1H,
Ar), 6.93 (m, 2H, Ar), 6.50 (d, 3J H-H 8 Hz, 1H, Ar), 3.34 (s, 3H,
2
OMeAr), 1.49 (s, 15H, C5Me5), 0.95 (d, J H-H 8 Hz, 9H, PMe3);
13C{1H} NMR (C6D6) δ 223.5 (d, J P-C 33 Hz, CO), 167.0
2
2
(ArOMe), 154.7 (d, J P-C 25 Hz, Aripso), 146.1 (Ar), 122.8 (Ar),
P r ep a r a tion of [F e(C5Me5)(CO){η2-H2BH(CH2C6H4-o-
OMe)}] (10). In a Schlenk tube were added 1 mmol (518 mg)
of 5a and 2 mmol (76 mg) of NaBH4 and then 15 mL of THF
cooled to -80 °C. The solution was then allowed to warm to
room temperature. The initial brown color turned yellow-
orange at -30 °C. The THF was evaporated to dryness, and
the residue was extracted with pentane (2 × 10 mL). Cooling
the resulting solution at -20 °C gave 0.301 mg (85%) of 10 as
119.8 (Ar), 107.8 (Ar), 92.1 (C5Me5), 53.6 (OMeAr), 19.2 (d, 1J P-C
25 Hz, PMe3), 10.2 (C5Me5); 31P{1H} NMR (C6D6/H3PO4 exter-
nal) δ 32.0 (s, PMe3); IR (pentane) 1907 (s, νCO).
Min or isom er : 1H NMR (C6D6) δ 7.47 (m, J H-H 7 Hz, 1H,
3
Ar), 7.09 (m, 2H, Ar), 6.63 (d, 3J H-H 8 Hz, 1H, Ar), 3.66 (s, 3H,
2
OMeAr), 1.54 (s, 15H, C5Me5), 0.88 (d, J H-H 8 Hz, 9H, PMe3);
13C{1H} NMR (C6D6) δ 223.6 (d, J P-C 34 Hz, CO), 166.7
2
2
3
brown microcrystals: 1H NMR (C6D6) δ 7.29 (dd, J H-H 7 Hz,
(ArOMe), 156.2 (d, J P-C 26 Hz, Aripso), 128.6 (Ar), 122.6 (Ar),
120.4 (Ar), 109.1 (Ar), 91.4 (C5Me5), 55.4 (OMeAr), 17.9 (d, 1J P-C
25 Hz, PMe3), 10.1 (C5Me5); 31P{1H} NMR (C6D6/H3PO4 exter-
nal) δ 36.3 (s, PMe3); IR (pentane) 1911 (s, νCO).
3
4
4J H-H 1.7 Hz, 1H, Ar), 7.06 (td, J H-H 8 Hz, J H-H 1.8 Hz, 1H,
3
4
3
Ar), 6.93 (td, J H-H 7 Hz, J H-H 1 Hz, 1H, Ar), 6.65 (d, J H-H
8
1
Hz, 1H, Ar), 6.35 (br pseudo-q, J B-H 108 Hz, 1H, BHterminal),
3.46 (s, 3H, OMeAr), 2.60 (br s, 2H, CH2), 1.39 (s, 15H, C5Me5),
-17.87 (br pseudo-q, 1J B-H 43 Hz, 2H, Fe-Hbridging): (the low-
field resonance at δ 6.35 is too broad to be observed in the
normal spectrum, but its presence is revealed upon B (55 ppm)
or/and bridging H (-17.87 ppm) decoupling); 13C{1H} NMR
(CDCl3) δ 218.8 (CO), 157.4 (ArOMe), 134.8 (Aripso), 130.3 (Ar),
125.3 (Ar) , 120.9 (Ar) , 110.8 (Ar), 90.8 (C5Me5), 55.0 (OMeAr),
33.3 (br m, BCH2), 10.1 (C5Me5); 11B{H} NMR (C6D6/C6H6,
Et2O‚BF3 as external reference) δ 55.33 (br s); IR (Nujol) 1962
(s, νCO); zero field Mo¨ssbauer data (298 K) IS ) 0.104 mm‚s-1
vs Fe, QS ) 1.898 mm‚s-1; high resolution MS (70 eV) (m/z)
calcd for [M - 2H]+ C19H25O2BFe 352.12968, found 352.1301.
Anal. Calcd for C19H27O2BFe: C, 64.45; H, 7.69. Found: C,
64.55; H, 7.62.
P r ep a r a tion of [F e(C5Me5)(CH3CN)2{η1-C(OMe)C6H4-o-
Cl}][CF 3SO3] (14). A CH3CN (200 mL) solution of 1.5 mmol
(833 mg) of 2b was irradiated (UV) for 5 h. The initial yellow
color turned yellow-brown. The CH3CN was evaporated to
dryness by using a trap to trap procedure. The oily residue
was washed with pentane (2 × 10 mL) to give a brown powder.
Compound 14, only stable in CH3CN, was not crystallized: 1H
3
3
NMR (CD3CN) δ 7.39 (d, J H-H 7.6 Hz, 1H, Ar), 7.36 (t, J H-H
3
3
7.5 Hz, 1H, Ar), 7.27 (t, J H-H 7.3 Hz, 1H, Ar), 6.90 (d, J H-H
7.3 Hz, 1H, Ar), 4.30 (s, 3H, OMe), 1.96 (s, CH3CN/CD3CN),
1.42 (s, 15H, C5Me5); 13C{1H} NMR (CD3CN) δ 321.0 (dC),
149.1 (Aripso), 134.0 (CN), 130.1 (Ar), 129.8 (Ar), 127.9 (Ar),
125.2 (ArCl), 124.0 (Ar), 94.6 (C5Me5), 65.3 (OMe), 9.5 (C5Me5),
2.0 (CH3CN/CD3CN).
P r ep a r a tion of [F e(C5Me5)(CO)(P Me3){η1-C(OMe)C6H4-
o-OMe}][CF 3SO3] (11). An excess of PMe3 was added to 518
mg (1 mmol) of 2a dissolved in 10 mL of CH2Cl2. The solution
was stirred for 30 min, and the maroon color became orange.
After removal of the solvent, the residue was washed with
ether (3 × 20 mL) and then crystallized from a CH2Cl2/ether
mixture. Orange crystals were collected (505 mg, 85%): 1H
P r ep a r a tion of [F e(C5Me5)(η2-d p p m ){η1-C(OMe)C6H4-
o-Cl}][CF 3SO3] (15). To a CH3CN solution of 1.2 mmol (692
mg) of 14 was added 1.2 mmol (398 mg) of dppm. The reaction
mixture was stirred for 16 h. The residue was washed with
ether (3 × 20 mL) to give an orange powder (85%): 1H NMR
3
(CD3CN) δ 7.60-7.25 (m, 23H, PPh2 + Ar), 6.45 (d, J H-H 6.9
Hz, 1H, Ar), 5.13 (dt, 2J H-H 15 Hz, 3J P-H 12 Hz, 1H, CH2), 4.62
3
2
3
NMR (CDCl3) δ 7.47 (m, J H-H 8 Hz, 1H, Ar), 7.12 (m, 2H,
(dt, J H-H 15 Hz, J P-H 10 Hz, 1H, CH2), 2.69 (s, 3H, OMe),
3
Ar), 6.93 (d, J H-H 8 Hz, 1H, Ar), 4.20 (s, 3H, OMe), 3.85 (s,
1.25 (s, 15H, C5Me5); 31P{1H} NMR (CD3CN/H3PO4 external)
2
2
2
3H, OMeAr), 1.82 (s, 15H, C5Me5), 1.37 (d, J P-H 13 Hz, 9H,
δ 32.77 (d, J P-P 77 Hz, PPh2), 29.07 (d, J P-P 77 Hz, PPh2);
2
2
PMe3); 13C{1H} NMR (CDCl3) δ 328.9 (d, J P-C 27 Hz, dC),
13C{1H} NMR (CD3CN) δ 307.7 (t, J P-C 28 Hz, dC), 147.7
2
216.7 (d, J P-C 30 Hz, CO), 148.4 (ArOMe), 137.8 (Aripso), 133.6
(Aripso), 136.9 (dd, CipsoPPh2), 135.7 (dd, CipsoPPh2), 133.9 (dd,
2 × CipsoPPh2), 132.3-127.5 (PPh2 + Ar), 127.1 (ArCl), 98.1 (C5-
Me5), 61.9 (OMe), 43.2 (t, 1J P-C 23 Hz, CH2), 10.9 (C5Me5). Anal.
(Ar), 131.7 (Ar), 121.5 (Ar), 111.3 (Ar), 98.7 (C5Me5), 67.9
(OMe), 55.4 (OMeAr), 17.6 (d, 1J P-C 32 Hz, PMe3), 10.1 (C5Me5);

132 Organometallics, Vol. 16, No. 1, 1997
Poignant et al.
Ta ble 3. Cr ysta llogr a p h ic Da ta for
[F e(C5Me5)(CO)2{η2-C(OMe)C6H4-o-Cl}][CF 3SO3] (5b)
Calcd for C44H44O4P2FeClSF3: C, 60.11; H, 5.04. Found: C,
59.56; H, 5.02.
P r ep a r a tion of [F e(C5Me5)(CO)(CH3CN){η1-C(OMe)-
C6H4-o-Cl}][CF 3SO3] (16). Complex 5b (0.5 mmol, 261 mg)
was dissolved in 5 mL of CH3CN, and the brown solution
immediately became deep-red. Crystallization from CH3CN/
Et2O gave red crystals (225 mg): 1H NMR (CD3CN, -40 °C) δ
formula
fw
C20H22ClF3FeO5S
522.74
temp
293(2) K
wavelength (Mo KR)
cryst system
space group
unit cell dimens
0.710 73 Å
orthorhombic
Pbca
a ) 12.700(3) Å
b ) 14.305(3) Å
c ) 24.390(5) Å
4431(2) Å3
3
7.41 (m, 3H, Ar), 7.03 (d, J H-H 7 Hz, 0.75H, Armaj, 75%), 6.83
3
(d, J H-H 7 Hz, 0.25H, Armin, 25%), 4.24 (s, 3H, OMe), 2.08 (s,
0.75H, CH3CNmin), 1.84 (s, 2.25H, CH3CNmaj), 1.66 (s, 15H,
C5Me5); 1H NMR (CD3CN, +50 °C) δ 7.43 (m, 3H, Ar), 6.99 (d,
3
1H, J H-H 7 Hz, Ar), 4.31 (s, 3H, OMe), 1.96 (s, 3H, CH3CN),
V
1.70 (s, 15H, C5Me5).
Z
8
1.567 Mg/m3
0.950 mm-1
Ma jor isom er : 13C{1H} NMR (CD3CN, -40 °C) δ 325.7
(dC), 219.8 (CO), 146.2 (Aripso), 132.5 (CN), 131.4 (Ar), 130.4
(Ar), 128.9 (Ar), 124.7 (ArCl), 123.6 (Ar), 119.8 (q, CF3SO3), 99.6
(C5Me5), 68.90 (OMe), 9.6 (C5Me5), 4.2 (CH3CN).
D(calcd)
abs coeff
F(000)
cryst size
θ range for data collcn
index ranges
reflcns collcd
indepdt reflcns
struct solution
2144
0.49 × 0.43 × 0.38 mm
2.72-22.55°
-2 e h e 13, 0 e k e 15, 0 e l e 26
3007
Min or isom er : 13C{1H} NMR (CD3CN, -40 °C) δ 332.0
(dC), 218.5 (CO), 147.9 (Aripso), 133.0 (CN), 131.5 (Ar), 130.8
(Ar), 128.7 (Ar), 124.1 (ArCl), 123.1 (Ar), 99.7 (C5Me5), 68.94
(OMe), 9.7 (C5Me5), 5.0 (CH3CN); IR (CH2Cl2) 1989 (s, νCO).
2902 (Rint ) 0.0125)
direct methods
0.490, 0.463
Ψ scans (Tmax , Tmin
refinement method
)
Anal. Calcd for
C22H25O5NFeClSF3: C, 46.87; H, 4.47.
full-matrix least squares on F2
2856/0/286
Found: C, 46.62; H, 4.51.
Rea ction of [F e(C5Me5)(CO)2{η1-CH(C6H4-o-OMe)}] (4a )
w ith O2. A Schlenk tube was charged with 0.38 mmol (150
mg) of 3a and cooled to -80 °C. Then 0.56 mmol (110 µL) of
Me3SiOSO2CF3 was added generating 4a in situ. Dioxygen
was bubbled through the resulting reaction mixture for 30 s,
and the solution was allowed to warm to room temperature.
The o-anisaldehyde o-MeOC6H4CHO was extracted with pen-
tane, and the triflate derivative [Fe(C5Me5)(CO)2(OSO2CF3)],
soluble in ether, was identified by comparison with an
authentic sample.31 Data for o-MeOC6H4CHO: 1H NMR
(CDCl3) δ 10.48 (s, 1H, CHO), 7.84 (d, 3J H-H 7.6 Hz, 1H, ArH6),
7.56 (t, 3J H-H 7.7 Hz, 1H, ArH4), 7.03 (t, 3J H-H 7.4 Hz, 1H, ArH5),
data/restaints/params
goodness-of-fit on F2
final R indices [I >2σ (I)]
R indices (all data)
1.056
a
b
R1 ) 0.0495, wR2 ) 0.0963
R1 ) 0.1107, wR2 ) 0.2327
largest diff peak and hole 0.416 and -0.316 e Å-3
a
Definition of R indices: R1 ) {∑(Fo - Fc)}/∑(Fo); wR2
)
{∑[w(Fo - Fc2)2]1/2}/{∑[w(Fo2)2}.
2
and results of the refinement are listed in Table 3. All data
processing was performed on a Viglen 486PC computer using
SHELXTL-PLUS35 and SHELXL 93.36 Lorentz-polarization
(Lp) corrections were applied as was a semi-empirical absorp-
tion correction based on five azimuthal Ψ-scans. The structure
was solved by a combination of direct methods (TREF) and
Fourier difference techniques. All non-hydrogen atoms were
refined with anisotropic displacement parameters, and hydro-
gen atoms were placed in idealized positions and allowed to
ride on the relevant carbon atom. In the final cycles of
3
7.00 (d, J H-H 8.2 Hz, 1H, ArH3), 3.93 (s, 3H, OMe); 13C{1H}
NMR (CDCl3) δ 189.9 (CHO), 161.9 (ArOMe), 136.0 (Ar), 128.6
(Ar), 124.9 (ArCHO), 120.7 (Ar), 111.7 (Ar), 55.7 (OMe); IR (CH2-
Cl2) 1601.9 (m, νCdO).
Rea ction of [Fe(C5Me5)(CH3CN)2{η1-C(OMe)C6H4-o-Cl}]-
[CF 3SO3] (14) w ith O2. Complex 14 (0.3 mmol, 173 mg) was
dissolved in 10 mL of CH3CN, and O2 was bubbled through
the solution for 30 s. The reaction mixture was stirred
overnight and the solvent removed under vacuum. The
residue was extracted with CDCl3 and the solution filtered
through a short alumina pad. The 1H NMR spectrum showed
the presence of the spectroscopically pure ester derivative
o-ClC6H4C(O)OMe: 1H NMR (CDCl3) δ 7.83 (dd, 3J H-H 7.8 Hz,
2
refinements the weighting scheme w ) 1/[σ2(Fo + (0.0366P)2
+ 14.03P], where P ) 2Fc2/3, was applied, as this gave a fairly
flat analysis of variance.
Ack n ow led gm en t. We are grateful to S. Sinbandhit
(CRMPO, Rennes, France) for helpful discussions. The
“Conseil Re´gional de Bretagne” is gratefully acknowl-
edged for a grant to G.P. This work was supported by
the CNRS and the European Union (Human Capital
and Mobility Network Contract No. ERBCHXCT940501).
4J H-H 1.7 Hz, 1H, Ar), 7.47 (dd, J H-H 8 Hz, J H-H 1.7 Hz, 1H,
Ar), 7.42 (td, 3J H-H 8 Hz, 4J H-H 1.7 Hz, 1H, Ar), 7.32 (td, 3J H-H
7.3 Hz, 4J H-H 1.7 Hz, 1H, Ar), 3.94 (s, 3H, OMe); 3C{1H} NMR
(CDCl3) δ 166.2 (CdO), 133.7 (Ar), 132.6 (Ar), 131.4 (Ar), 131.1
(Ar), 130.2 (Ar), 126.6 (Ar), 52.3 (OMe).
3
4
Su p p or tin g In for m a tion Ava ila ble: Tables of complete
atom coordinates and U values, anisotropic displacement
parameters, and complete bond distances and angles and
ORTEP diagrams for 5b (5 pages). Ordering information is
given on any current masthead page.
Str u ctu r e Deter m in ation of [Fe(C5Me5)(CO){η2-C(OMe)-
C6H4-o-Cl}][CF 3SO3] (5b). Crystals of 5b suitable for X-ray
diffraction analysis were grown from a solution of a solvent
mixture of CH2Cl2/Et2O by slow evaporation of the solvent. A
crystal was mounted on the end of a glass fiber and transferred
to a Stoe four-circle diffractometer equipped with Mo KR
radiation. The unit cell was determined from 25 randomly
selected reflections. Crystal data, data collection parameters,
OM960711Z
(35) SHELXTL-PLUS Rev. 4.0, Siemens Analytical X-ray Instru-
ments, Madison, WI, 1990.
(36) SHELXL 93: Sheldrick, G. M. University of Go¨ttingen, Ger-
many, 1993.