Synthesis, structures, and electrochemistry of group 6 aminocarbenes with a P-chelating 1′-(diphenylphosphino)ferrocenyl substituent

Article abstract of DOI:10.1021/om040007f

Ferrocene amides Ph₂PfcC(O)NR₂ (1; fc = ferrocene-1,1′-diyl, NR₂ = NEt₂ (a), morpholin4-yl (b)) react with [Cr(CO)₅]^2- in the presence of Me ₃SiCl to give easily separable mixtures of the respective P-chelated carbene [Cr(CO)₄(Ph₂PfcC(NR₂)- κ²C¹,P)] (2) and a phosphine complex, [Cr(CO) ₅(1-κP)] (3). A similar reaction between 1a and [W(CO) ₅]^2- is more complex, affording a mixture of the nonchelated carbene [Cr(CO)₄{Ph₂PfcC(NEt) ₂-kC¹}] (5), trimetallic carbene [(u-1kC ¹,2kP-Ph₂PfcC(NEt₂)){W(CO)₅} ₂] (6), and the phosphine complex [W(CO)₅{1a-kP}] (4). Removal of 4 by chromatography and heating the mixture of 5 and 6 in toluene gives another mixture containing carbene analogous to 2, [W(CO) ₄(Ph₂PfcC(NEt₂)-k²C¹,P)] (7), unreacted 6, and [W(CO)₅{Ph₂PfcCHO-kP}] (8) as a decomposition product. In contrast, the reaction of la with the iron carbonylate [Fe(CO)₄]^2- under identical conditions yields solely [Fe(CO)⁴{1a-kP}] (9). All compounds except for 5 were isolated and characterized by spectral methods. The structures of 2aCH ₂Cl₂, 2b, 6CHCl₃, 7, and 9 were determined by single-crystal X-ray diffraction. An electrochemical study showed that whereas compounds 1 and 3 behave as a simple system (ferrocene) and two localized redox systems (ferrocene and chromium), respectively, carbenes 2 are electronically delocalized systems, where the redox changes probably occur in the whole molecule.

Full text of DOI:10.1021/om040007f

Organometallics 2004, 23, 2541-2551
2541
Syn th esis, Str u ctu r es, a n d Electr och em istr y of Gr ou p 6
Am in oca r ben es w ith a P -Ch ela tin g
1′-(Dip h en ylp h osp h in o)fer r ocen yl Su bstitu en t
Ludeˇk Meca,† Dalimil Dvorˇa´k,† J irˇ´ı Ludv´ık,‡ Ivana C´ısarˇova´,§ and
Petr Sˇteˇpnicˇka*,§
Department of Organic Chemistry, Institute of Chemical Technology, Prague, Czech Republic,
J . Heyrovsky´ Institute of Physical Chemistry, Academy of Sciences of the Czech Republic,
Prague, Czech Republic, and Department of Inorganic Chemistry, Faculty of Science,
Charles University, Hlavova 2030, 128 40 Prague 2, Czech Republic
Received J anuary 15, 2004
Ferrocene amides Ph2PfcC(O)NR2 (1; fc ) ferrocene-1,1′-diyl, NR2 ) NEt2 (a ), morpholin-
4-yl (b)) react with [Cr(CO)5]2- in the presence of Me3SiCl to give easily separable mixtures
of the respective P-chelated carbene [Cr(CO)4(Ph2PfcC(NR2)-κ2C1,P)] (2) and a phosphine
complex, [Cr(CO)5(1-κP)] (3). A similar reaction between 1a and [W(CO)5]2- is more complex,
affording a mixture of the nonchelated carbene [Cr(CO)4{Ph2PfcC(NEt)2-κC1}] (5), trimetallic
carbene [(µ-1κC1,2κP-Ph2PfcC(NEt2)){W(CO)5}2] (6), and the phosphine complex [W(CO)5-
{1a -κP}] (4). Removal of 4 by chromatography and heating the mixture of 5 and 6 in toluene
gives another mixture containing carbene analogous to 2, [W(CO)4(Ph2PfcC(NEt2)-κ2C1,P)]
(7), unreacted 6, and [W(CO)5{Ph2PfcCHO-κP}] (8) as a decomposition product. In contrast,
the reaction of 1a with the iron carbonylate [Fe(CO)4]2- under identical conditions yields
solely [Fe(CO)4{1a -κP}] (9). All compounds except for 5 were isolated and characterized by
spectral methods. The structures of 2a ‚CH2Cl2, 2b, 6‚CHCl3, 7, and 9 were determined by
single-crystal X-ray diffraction. An electrochemical study showed that whereas compounds
1 and 3 behave as a simple system (ferrocene) and two localized redox systems (ferrocene
and chromium), respectively, carbenes 2 are electronically delocalized systems, where the
redox changes probably occur in the whole molecule.
In tr od u ction
at the ferrocene unit remains unexplored. In 1982,
Herrmann and Ugi6 reported the unexpected products
resulting from the reaction of tungsten hexacarbonyl
and (R,Rp)-1-{1-(dimethylamino)ethyl}-2-lithioferrocene.7
Three years later, Cullen et al.8 described the use of a
functionalized lithium reagent, 1′-(diphenylphosphino)-
ferrocenyllithium (I, Scheme 1),9 in the procedure orig-
inally developed for the preparation of Fischer-type
alkoxycarbenes to afford a mixture of chelated ferrocene
methoxycarbenes II (M ) Cr, W; 20-40%) and zwitter-
ionic compounds III (10-20%).
Compounds combining different organometallic moi-
eties and their physicochemical properties have at-
tracted considerable attention. The first ferrocenylated
group 6 metal Fischer-type carbenes, [(OC)5MdC(Fc)-
(OR)]1 and [(OC)5MdC(Fc)(NR2)],1c where M ) Cr, Mo,
W; Fc ) ferrocenyl, and R is usually an alkyl group,
were synthesized shortly after the first article concern-
ing these types of compounds appeared.2 Since then,
other ferrocene carbenes have been synthesized and
these carbenes have been converted to their respective
carbynes,3 applied in the synthesis of ferrocenylated
organic molecules,4 and studied as push-pull nonlinear
optical materials (Scheme 1).5 However, the chemistry
of ferrocene carbenes bearing other functional group(s)
More recently, we reported the carboxylation of I with
carbon dioxide, providing 1′-(diphenylphosphino)ferro-
cenecarboxylic acid, [Fe(η5-C5H4PPh2){η5-C5H4CO2H}]
(4) Selected examples: (a) Connor, J . A.; Lloyd, J . P. J . Chem. Soc.,
Dalton Trans. 1973, 17. (b) Do¨tz, K. H.; Dietz, R.; Neugebauer, D.
Chem. Ber. 1979, 112, 1486. (c) Barluenga, J .; Ferna´ndez-Acebes, A.;
Trabanco, A. A.; Flo´rez, J . J . Am. Chem. Soc. 1997, 119, 7591. (d)
Mongin, C.; Ortin, Y.; Lugan, N.; Mathieu, R. Eur. J . Inorg. Chem.
1999, 739. (e) Zora, M.; Gu¨ngo¨r, E. U¨ . Tetrahedron Lett. 2001, 422,
4733. (f) Zora, M.; Yucel, B.; Peynircioglu, N. B. J . Organomet. Chem.
2002, 656, 11.
* To whom correspondence should be addressed. E-mail: stepnic@
natur.cuni.cz.
† Institute of Chemical Technology.
‡ Academy of Sciences of the Czech Republic.
§ Charles University.
(1) (a) Connor, J . A.; J ones, E. M.; Lloyd, J . P. J . Organomet. Chem.
1970, 24, C20. (b) Moser, G. A.; Fischer, E. O.; Rausch, M. D. J .
Organomet. Chem. 1971, 27, 379. (c) Connor, J . A.; Lloyd, J . P. J . Chem.
Soc., Dalton Trans. 1972, 1470 (the aminocarbenes were synthesized
from the respective alkoxycarbenes by reacting with secondary amines).
(2) Fischer, E. O.; Maasbo¨l, A. Angew. Chem., Int. Ed. Engl. 1964,
3, 580.
(3) (a) Fischer, E. O.; Schluge, M.; Besenhard, J . O.; Friedrich, P.;
Huttner, G.; Kreissl, F. R. Chem. Ber. 1978, 111, 3530. (b) Fischer, E.
O.; Gammel, F. J .; Besenhard, J . O.; Frank, A.; Neugebauer, D. J .
Organomet. Chem. 1980, 191, 261.
(5) (a) J ayaprakash, K. N.; Ray, P. C.; Matsuoka, I.; Bhadbhade,
M. M.; Puranik, V. G.; Das, P. K.; Nishihara, H.; Sarkar, A. Organo-
metallics 1999, 18, 3851. For similar compounds see, e.g.: (b) Ma-
comber, D. W.; Madhukar, P.; Rogers, R. D. Organometallics 1989, 8,
1275. (c) Briel, O.; Fehn, A.; Beck, W. J . Organomet. Chem. 1999, 578,
247.
(6) Herrmann, R.; Ugi, I. Angew. Chem. 1982, 94, 798.
(7) Marquarding, D.; Klusacek, H.; Gokel, G.; Hoffmann, P.; Ugi, I.
J . Am. Chem. Soc. 1970, 92, 5389.
(8) Butler, I. R.; Cullen, W. R.; Einstein, F. W. B.; Willis, A. C.
Organometallics 1985, 4, 603.
10.1021/om040007f CCC: $27.50 © 2004 American Chemical Society
Publication on Web 04/21/2004

2542 Organometallics, Vol. 23, No. 11, 2004
Meca et al.
Sch em e 1
Sch em e 2a
(Hdpf),10 and studied the coordination chemistry11 and
further synthetic utility12 of this organometallic car-
boxyphosphine ligand. We have shown that Hdpf can
act as a chelating ligand (as the dpf- anion in [Rh(L)-
(CO)(dpf-κ2O,P)]11c) and that in complexes with P-
coordinated Hdpf the ferrocene unit and the metal
center are electronically coupled.11a Since some 1,1′-
chelating ferrocene ligands bring the ferrocene iron and
the ligated metal into proximity, which allows for a
direct donation from the electron-rich iron atom to the
chelated metal (FefM),13 we decided to synthesize the
Hdpf amides [Fe(η5-C5H4PPh2){η5-C5H4C(O)NR2}] (1)
and convert them into so far unknown, P-chelating
ferrocene aminocarbenes analogous to II. In this con-
tribution we report on the characterization, solid-state
structures, and electrochemistry of the products arising
from the reaction of chromium, tungsten, and iron
carbonylate salts and 1′-(diphenylphosphino)ferrocene
carboxamides.
a
Legend: NR2 ) NEt2 (a ), morpholin-4-yl (b); EDC ) N-[3-
(dimethylamino)prop-1-yl]-N′-ethylcarbodiimide; HOBt ) 1-
hydroxy-1,2,3-benzotriazole.
Resu lts a n d Discu ssion
Syn th esis a n d Ch a r a cter iza tion of Am id es a n d
Ch r om iu m Com p lexes. The amides Ph2PfcC(O)NR2
(fc ) ferrocene-1,1′-diyl; NR2 ) NEt2 (1a ), morpholin-
4-yl (1b)) were obtained by amidation of Hdpf10 with
diethylamine and morpholine in nearly quantitative
yields as viscous orange oils, which solidify upon stand-
ing to rusty brown, somewhat waxy solids. The amides
were subsequently reacted with the carbonylate salts
[M(CO)5]2- (M ) Cr, W) generated in situ14 and an
excess of Me3SiCl, as reported previously by Hegedus
et al.15 The reaction of 1a with [Cr(CO)5]2- (Scheme 2)
proceeded with the formation of two major products,
which were separated by column chromatography and
characterized as the P-chelated carbene 2a (46%) and
the phosphine carbonyl complex 3a (37%). A similar
reaction with the amide 1b afforded a pair of analogous
compounds, 2b (19%) and 3b (38%).
The chelated carbenes 2a and 2b were obtained as
bright orange crystalline solids. They are fairly stable
when stored as solids in the dark but decompose in
daylight and in solution. The carbenes lack typical
amide νCdO bands in their IR spectra and show char-
acteristic low-field signals in the 13C NMR spectra due
to the carbene carbons (δC ca. 280) split into doublets
by the phosphorus of the phosphine group (2J PC ) 13
Hz). In addition, the 13C NMR spectra show a markedly
downfield-shifted, phosphorus-coupled signal of the
ferrocene Cipso attached to the carbene carbon (cf. δC
(9) I can be prepared either by opening of the strained ferro-
cenophane ring in (ferrocene-1,1′-diyl)phenylphosphine9a,b with phenyl-
lithium9b,c or, alternatively, by a stepwise metalation/functionalization
of 1,1′-dibromoferrocene.9d,e Prior to the report concerning compounds
II and III, reagent I has been utilized in the synthesis of ferraphosphino-
ferrocenophanes.9f,g (a) Osborne, A. G.; Whiteley, R. H.; Meads, R. E.
J . Organomet. Chem. 1980, 193, 345. (b) Seyferth, D.; Withers, H. P.,
J r. Organometallics 1982, 1, 1275. (c) Seyferth, D.; Withers, H. P., J r.
J . Organomet. Chem. 1980, 185, C1. (d) Butler, I. R.; Davies, R. L.
Synthesis 1996, 1350. (e) Dong, T.-Y.; Lai, L.-L. J . Organomet. Chem.
1996, 509, 131. (f) Butler, I. R.; Cullen, W. R. Organometallics 1984,
3, 1846. (g) Butler, I. R.; Cullen, W. R.; Rettig, S. J . Organometallics
1987, 6, 872.
(10) Podlaha, J .; Sˇteˇpnicˇka, P.; C´ısarˇova´, I.; Ludv´ık, J . Organo-
metallics 1996, 15, 543.
(11) Representative examples: (a) Sˇteˇpnicˇka, P.; Gyepes, R.;
Lavastre, O.; Dixneuf, P. H. Organometallics 1997, 16, 5089. (b)
Sˇteˇpnicˇka, P.; Podlaha, J .; Gyepes, R.; Pola´sˇek, M. J . Organomet.
Chem. 1998, 552, 293. (c) Sˇteˇpnicˇka, P.; C´ısarˇova´, I. J . Chem. Soc.,
Dalton Trans. 1998, 2807. (d) Sˇteˇpnicˇka, P.; Gyepes, R.; Podlaha, J .
Collect. Czech. Chem. Commun. 1998, 63, 64. (e) Sˇteˇpnicˇka, P.;
C´ısarˇova´, I.; Podlaha, J .; Ludv´ık, J .; Nejezchleba, M. J . Organomet.
Chem. 1999, 582, 319. For other ferrocene phosphino carboxylic acids,
see the following. (f) Zhang, T. Shimanuki, T. Kida, Y. Nakatsuji, I.
Ikeda, I. J . Org. Chem. 1999, 64, 6247 and references cited therein
(esters and amides). (g) You, S.-L.; Hou, X.-L.; Dai, L.-X.; Cao, B.-X.;
Sun, J . Chem. Commun. 2000, 1933. (h) Longmire, J . M.; Wang, B.;
Zhang, X.; Tetrahedron Lett. 2000, 41, 5435. (i) Sˇteˇpnicˇka, P. New J .
Chem. 2002, 26, 567. (j) Sˇteˇpnicˇka, P.; C´ısarˇova´, I. Organometallics
2003, 22, 1728.
(12) So far, Hdpf has been used in the synthesis of ferrocene
oxazolines12a,b and [1′-(diphenylphosphino)ferrocenyl]methanol:12c (a)
Zhang, W.; Yoneda, Y.; Kida, T.; Nakatsuji, Y.; Ikeda, I. Tetrahedron:
Asymmetry 1998, 9, 3371 (as Me ester). (b) Drahonˇovsky´, D.; C´ısarˇova´,
I.; Sˇteˇpnicˇka, P.; Dvorˇa´kova´, H.; Malonˇ, P.; Dvorˇa´k, D. Collect. Czech.
Chem. Commun. 2001, 66, 588. (c) Sˇteˇpnicˇka, P.; Basˇe, T. Inorg. Chem.
Commun. 2001, 4, 682.
(13) The FefM dative bond has been observed in complexes with
chelating 1,1′-dichalcogenolatoferrocene(2-),13a-e 1,1′-bis(diphenylphos-
phino)ferrocene13f,g and also with some ferrocene diamide13h and bis-
(pyridyl)13i ligands. (a) Seyferth, D.; Hames, B. W.; Rucker, T. G.;
Cowle, M.; Dickson, R. S. Organometallics 1983, 2, 472. (b) Cowie, M.;
Dickson, R. S. J . Organomet. Chem. 1987, 326, 269. (c) Akabori, S.;
Kumagai, T.; Shirahige, T.; Sato, S.; Kawazoe, K.; Tamura, C.; Sato,
M. Organometallics 1987, 6, 526. (d) Akabori, S.; Kumagai, T.;
Shirahige, T.; Sato, S.; Kawazoe, K.; Tamura, C.; Sato, M. Organo-
metallics 1987, 6, 2105. (e) Takemoto, S.; Kuwata, S.; Nishibayashi,
Y.; Hidai, M. Inorg. Chem. 1998, 37, 6428. (f) Sato, M.; Sekino, M.;
Akabori, S. J . Organomet. Chem. 1988, 344, C31. (g) Sato, M.; Shigeta,
H.; Sekino, M.; Akabori, S. J . Organomet. Chem. 1993, 458, 199. (h)
Shafir, A.; Rheingold, J . J . Am. Chem. Soc. 2001, 123, 9212. (i) Enders,
M.; Kohl, G.; Pritzkow, H. Organometallics 2002, 21, 1111.
3
109.24 (d, J PC ) 5 Hz) for 2a and 81.32 (s) for 3a ) and
three signals due to the carbonyl ligands, as expected
for an asymmetric cis-[Cr(L1)(L2)(CO)4] complex. In the
31P NMR spectra 2a and 2b exhibit singlets shifted
significantly downfield from those of the parent amides
and also the phosphine complexes 3a and 3b (δP 58.1
(2a ), 58.5 (2b)). The structures of 2a and 2b were
corroborated by X-ray crystallography (see below).
The side products 3a and 3b are rusty orange,
noncrystallizing solids, showing strong amide carbonyl
(14) Borel, C.; Hegedus, L. S.; Krebs, J .; Satoh, Y. J . Am. Chem.
Soc. 1987, 109, 1101.
(15) (a) Imwinkelried, R.; Hegedus, L. S. Organometallics 1988, 7,
702. (b) Schwindt, M. A.; Lejon, T.; Hegedus, L. S. Organometallics
1990, 9, 2814.

Group 6 Aminocarbenes with a Ferrocenyl Substituent
Organometallics, Vol. 23, No. 11, 2004 2543
Sch em e 3
stretching bands in the IR spectra (3a , 1614 cm-1; 3b,
1623 cm-1). The 1H and 13C NMR spectra of 3 are
indicative of unchanged carboxamide groups and display
resonances due to carbonyl ligands (13C NMR) at posi-
tions nearly identical with those of [Cr(CO)5(Hdpf-κP)].16
Likewise, the 31P NMR signals (δP 47.3 for 3a and 3b)
compare nicely to those of [Cr(CO)5(Hdpf-κP)] (δP 47.7),
thus supporting the formulation of 3 as [Cr(CO)5(1-κP)],
where the amides behave as simple phosphine ligands.
P r ep a r a tion of Tu n gsten An a logu es. In compari-
son to the chromium system, the reactions occurring
with tungsten carbonylate under analogous conditions
are more complex. The reaction of [W(CO)5]2- with 1a
and Me3SiCl gave a mixture of nonchelated carbene 5,
trinuclear, ferrocene-bridged (µ-1κC1:2κP) complex 6,
and the expected side product, [W(CO)5(1a -κP)] (4)
(Scheme 3). To convert 5, which is an apparent precur-
sor of a P-chelated carbene, into a complex analogous
to 2a , the mixture of 5 and 6 was heated in toluene (80
°C/4 h) and the resulting material separated by chro-
matography to give (in order of increasing polarity)
unchanged 6, P-chelated carbene 7, and [W(CO)5(Ph2-
PfcCHO-κP)] (8) as a decomposition product.17 All
compounds were isolated in pure form and characterized
except for 5, which could not be separated from 6 due
to similar retention properties; the spectral data for 5
were obtained by subtracting the signals due to 6 from
the spectra of the 5/6 mixture. The structures of 6 and
7 were determined by single-crystal X-ray diffraction
(see below).
Sch em e 4
at δC ca. 261 for the P-chelated carbene 7. The 13C
NMR spectra are also indicative of the CO substitution
at tungsten: carbene 5 shows two (intensity 1 + 4) 183W-
coupled signals, while the trinuclear complex 6 exhibits
two such sets, one of which is further split into doublets
by the phosphine group. The chelated carbene 7 displays
three different phosphorus-coupled CO signals (inten-
sity 1 + 1 + 2). In addition, the carbenes show 31P NMR
shifts typical of an uncoordinated (5, δP -18.2), P-
coordinated (6, δP 11.0), or P-chelating (7, δP 27.9)
ferrocenylphosphino groupswith (6 and 7) or without
(5) 183W satellites.
On the other hand, the phosphine complexes 4 and 8
show 13C NMR signals due to a carbonyl group (amide
or aldehyde) and two phosphorus-coupled signals for the
tungsten-bonded CO ligands with 183W satellites. These
features, as well as the 31P NMR shifts (δP; 4, 11.2; 8,
11.1), correspond nicely to a complex with a P-coordi-
1
nated Hdpf, [W(CO)5(Hdpf-κP)] (cf. δP 10.9, J WP ) 247
Hz),16 and, in the case of 8, also to IR and NMR spectra
of uncoordinated Ph2PfcCHO (CHO: δH 9.67, δC 193.44;
νCdO 1677 s, 1662 s).12c
Compounds 5-8 are easily distinguishable by NMR
spectroscopy. Similar to the case for the chromium
analogues, the conversion of the amide group into a
carbene is reflected by a disappearance of the νCdO
amide signal in the IR spectra and by a typical low-
field carbene signal in the 13C NMR spectra at about
δC ca. 251 for the nonchelated carbenes 5 and 6, and
Rea ction w ith Ir on Ca r bon yla te. The reaction of
[Fe(CO)4]2- with 1a as described above for chromium
carbonylate gave the ochre phosphine complex 9 as the
only isolated product (Scheme 4; 56% yield). The com-
pound shows typical amide and CO signals in the IR
and NMR spectra, and its 13C and 31P NMR parameters
correspond with the spectra of the related complexes
[Fe(dppf-κP)(CO)4] and [(µ-dppf){Fe(CO)4}2] (dppf ) 1,1′-
bis(diphenylphosphino)ferrocene).18 In addition, the struc-
ture of 9 was determined by single-crystal X-ray dif-
fraction (see below). The exclusive formation of 9 is
rather surprising, in view of the fact that tertiary
aromatic, heterocyclic amides and HC(O)NMe2 react
(16) Lukesˇova´, L.; Ludv´ık, J .; C´ısarˇova´, I.; Sˇteˇpnicˇka, P. Collect.
Czech. Chem. Commun. 2000, 65, 1897.
(17) Compound 8 was detected also as a minor impurity in a mixture
of 5 and 6 which had been recovered from a CDCl3 solution after NMR
measurements and analyzed again after standing for about 1 month
at +4 °C in the dark. It is known that aldehydes result from hydrolysis
of alkoxycarbenes17a and were observed as side products in reactions
of aminocarbenes at elevated temperatures.17b,c (a) Aumann, R.;
Hinterding, P.; Kru¨ger, C.; Goddard, R. J . Organomet. Chem. 1993,
459, 145. (b) Sierra, M. A.; del Amo, J . C.; Mancheo, M. J .; Go´mez-
Gallego, M. J . Am. Chem. Soc. 2001, 123, 851. (c) Woodgate, P. D.;
Sutherland, H. S.; Rickard, C. E. F. J . Organomet. Chem. 2001, 627,
206.
(18) (a) Kim, T.-J .; Kwon, K.-H.; Kwon, S.-C.; Baeg, J .-O.; Lee, D.-
H. J . Organomet. Chem. 1990, 389, 205. (b) Kim, T.-J .; Kwon, S.-C.;
Kim, Y.-H.; Heo, N. H.; Teeter, M. T.; Yamano, A. J . Organomet. Chem.
1991, 426, 71.

2544 Organometallics, Vol. 23, No. 11, 2004
Meca et al.
Ta ble 1. Selected Bon d Dista n ces (Å) a n d An gles (d eg) for 2a ‚CH2Cl2 (M ) Cr ) a n d 7 (M ) W)a
2a ‚CH2Cl2
7
2a ‚CH2Cl2
7
Fe-Cg(1)
M-P
1.651(1)
2.3898(6)
1.813(2)
1.834(2)
1.838(2)
2.148(2)
1.499(3)
1.326(3)
1.495(3)
1.478(3)
1.650(1)
2.5391(9)
1.800(3)
1.839(3)
1.841(3)
2.268(4)
1.510(5)
1.324(4)
1.489(4)
1.482(4)
Fe-Cg(2)
M-C(28)
1.6475(9)
1.860(2)
1.150(3)
1.884(2)
1.154(3)
1.891(2)
1.147(3)
1.857(2)
1.153(3)
1.644(1)
1.985(4)
1.154(5)
2.031(3)
1.151(4)
2.018(4)
1.150(5)
2.000(4)
1.146(5)
P-C(6)
C(28)-O(2)
M-C(29)
P-C(16)
P-C(22)
M-C(11)
C(1)-C(11)
C(11)-N
N-C(12)
N-C(14)
C(29)-O(3)
M-C(30)
C(30)-O(4)
M-C(31)
C(31)-O(5)
Cp(1)-Cp(2)
3.3(1)
2.1(2)
P-M-C(11)
91.79(6)
103.95(9)
98.43(9)
100.88(9)
90.8(1)
C(1)-C(11)-N
C(11)-N-C(12)
C(11)-N-C(14)
111.2(2)
125.5(2)
123.4(2)
109.9(3)
126.2(3)
122.8(3)
C(6)-P-C(16)
C(6)-P-C(22)
C(16)-P-C(22)
101.9(1)
101.0(1)
101.3(1)
a
Ring plane definitions: Cp(1), C(1-5); Cp(2), C(6-10). Cg1 and Cg2 are the respective ring centroids.
F igu r e 1. View of the molecular structure of 2a ‚CH2Cl2.
The solvate molecule is omitted. Thermal motion ellipsoids
are drawn at the 30% probability level.
F igu r e 2. View of the molecular structure of 7. Thermal
motion ellipsoids are drawn at the 30% probability level.
) 2.546(2) Å),21 while the distances in 7 compare
favorably to those in its methoxy analogue II (M ) W;8,22
(WdC ) 2.20 Å, W-P ) 2.55 Å). In all cases, the lower
trans influence of phosphine and carbene donors is
reflected by a slight shortening of the M-CO bonds
trans to these ligands (relatively by ca. 2%),23 while all
the MC-O bond lengths remain virtually identical.
The ferrocene unit in carbenes 2a , 2b, and 7 remains
essentially undisturbed, showing a maximum cyclo-
smoothly with [Fe(CO)4]2- under identical conditions,
affording the respective iron aminocarbenes.19
Str u ctu r e Deter m in a tion . Ca r ben es 2 a n d 7. The
overall structures of the chelated carbenes 2a ‚CH2Cl2
(Figure 1, Table 1), 7 (Figure 2, Table 1), and 2b (Figure
3, Table 2) are similar and, hence, will be discussed
jointly. The bite angles of the (phosphinoferrocenyl)-
methylidene ligand (P-M-C11) as well as other inter-
ligand angles in carbenes 2 and 7 do not differ much
from the octahedral values. The coordination spheres
are thus asymmetric only in the metal-donor distances,
which themselves are unexceptional when compared to
those of similar compounds. For instance, the Cr-P
distances are similar to those of [Cr(CO)5(Hdpf-κP)]
(Cr-P ) 2.413(6) Å),16 [(µ-dppf){Cr(CO)5}2] (Cr-P )
2.389(2) Å),20 and trans-[PtCl2{(µ-dppf)(Cr(CO)5)}2] (Cr-P
(19) Dvorˇa´k, D. Organometallics 1995, 14, 570.
(20) Hor, T. S. A.; Phang, L.-T.; Liu, L.-K.; Wen, Y.-S. J . Organomet.
Chem. 1990, 397, 29.
(21) Phang, L.-T.; Au-Yeung, S. C. F.; Hor, T. S. A.; Khoo, S. B.;
Zhou, Z.-Y.; Mak, T. C. W. J . Chem. Soc., Dalton Trans. 1993, 165.
(22) The structural data were retrieved from the Cambridge Crys-
tallographic Database; coden CUKZUD.
(23) Wang, C.-C.; Wang, Y.; Liu, H.-J .; Lin, K.-J .; Chou, L.-K.; Chan,
K.-S. J . Phys. Chem. A 1997, 101, 8887.

Group 6 Aminocarbenes with a Ferrocenyl Substituent
Organometallics, Vol. 23, No. 11, 2004 2545
Ta ble 2. Selected Bon d Dista n ces (Å) a n d An gles
(d eg) for 2ba
dienyl rings in the same direction. In addition, the
ferrocene cyclopentadienyls are rotated from a synclinal
eclipsed conformation (τ ) 5.9(2)° (2a ), 10.9(2)° (2b), and
12.6(3)°; τ is the torsion angle C1-Cg1-Cg2-C6, see
Tables 1 and 2 for definitions), bringing the metal-
ligating groups into a position which may further relax
the possible steric strain.
Fe-Cg(1)
Cr-P
1.6448(8)
2.4092(6)
1.809(2)
1.833(2)
1.842(2)
2.139(2)
1.500(2)
1.325(2)
1.475(2)
1.491(2)
1.428(2)
1.424(2)
Fe-Cg(2)
1.6391(8)
1.848(2)
1.157(2)
1.890(2)
1.155(2)
1.888(2)
1.151(2)
1.854(2)
1.155(2)
1.515(3)
1.515(3)
Cr-C(28)
P-C(6)
C(28)-O(2)
Cr-C(29)
P-C(16)
P-C(22)
Cr-C(11)
C(1)-C(11)
C(11)-N
N-C(12)
N-C(15)
O(1)-C(13)
O(1)-C(14)
C(29)-O(3)
Cr-C(30)
C(30)-O(4)
Cr-C(31)
6‚CHCl3. The structure of complex 6 (Figure 4, Table
3) combines “independent” phosphine- and carbene-
substituted W(CO)5 groups. Similarly to the above cases,
the M-CO bonds trans to the phosphine and carbene
in both W(CO)5 units are slightly shorter than the other
ones and the asymmetry is relayed further to the MC-O
bonds, which are longer in trans positions. The WdC
(2.284(4) Å) and W-P (2.545(1) Å) distances differ only
insignificantly from 7, further confirming the non-
strained nature of carbene 7. However, a comparison
of the structure of 6 with those of P-chelated carbenes
2 and 7 reveals some differences in the geometry of the
ferrocene framework: complex 6 shows a notably higher
tilt of the cyclopentadienyl rings (9.2(2)°) and the
conformation of the ferrocene unit, which is devoid of
the geometric constraints imposed by cis chelation, is
more opened (τ ) 88.3(4)°) to a position almost exactly
halfway between synclinal eclipsed (τ ) 72°) and anti-
clinal staggered (τ ) 108°).
C(31)-O(5)
C(12)-C(13)
C(14)-C(15)
Cp(1)-Cp(2)
2.1(1)
90.15(5)
103.97(8)
100.75(8)
99.50(8)
111.0(1)
C(11)-N-C(12)
C(11)-N-C(15)
C(12)-N-C(15)
N-C(12)-C(13)
N-C(15)-C(14)
C(13)-O(1)-C(14)
124.6(2)
127.4(2)
109.0(1)
109.5(2)
108.8(2)
110.1(1)
P-Cr-C(11)
C(6)-P-C(16)
C(6)-P-C(22)
C(16)-P-C(22)
C(1)-C(11)-N
a
Definitions of the ring planes: Cp(1), C(1-5); Cp(2), C(6-10).
Cg(1) and Cg(2) are the respective ring centroids.
Com p lex 9. The molecular structure of 9, along with
selected geometric parameters, is shown in Figure 5.
The complex possesses a trigonal-bipyramidal structure
with the phosphine ligand attached in an axial position.
The coordination geometry at Fe2 is unsymmetric in the
Fe2-donor distances (Fe2-P vs four shorter, almost
identical Fe2-CO bonds) but displays the regular
interligand angles, not differing much from those in the
related complexes [Fe(dppf-κP)(CO)4] and [(µ-dppf-1κP:
2κP′){Fe(CO)4}2].18b The ferrocene unit adopts a confor-
mation between anticlinal staggered and anticlinal
eclipsed, although closer to the latter (τ ) 132.7(2)°),
and shows a negligible tilt of the cyclopentadienyl rings
(4.3(1)°). Its amide substituent remains untouched by
coordination of the phosphino part, showing a geometry
typical for simple organic amides,24 but slightly rotated
from the plane of its parent cyclopentadienyl ring
(dihedral angle 20.3(2)°).
Electr och em istr y. The amides 1 and the series of
chromium complexes 2 and 3 were studied by cyclic
voltammetry on a stationary platinum-disk electrode
and by voltammetry on the rotating platinum-disk
electrode (Pt-RDE) in dichloromethane. The amides
exhibit one-electron reversible oxidation waves at simi-
lar potentials due to the ferrocene backbone (Table 4).
The potentials are approximately 100 mV more nega-
tive than that of Hdpf (E° ) 0.32 V vs ferrocene/
ferrocenium),15,10 indicating an easier oxidation of 1,
which is in accordance with a lower electron-withdraw-
ing ability (-I) and a higher +M effect of an amino
group as compared to that of a hydroxy group.25 The
redox response of the phosphine complexes 3 is also
rather straightforward: the complexes undergo two one-
electron, reversible oxidations. The first one, around
0.30 V, can be attributed to the ferrocene unit (ferrocene/
F igu r e 3. View of the molecular structure of 2b. Thermal
motion ellipsoids are drawn at the 30% probability level.
pentadienyl ring tilt of 3.3(1)° for 2a . The geometries
of the phosphine groups compare well to those of
complexes with P-bonded Hdpf,11a-e and the C1-C11
distances are identical with that in 9, where the amide
group remains intact. However, the substituents at the
ferrocene unit in the carbenes are disposed from the
planes of their parent cyclopentadienyl rings, in the
same fashion for all the compounds: the phosphorus
atoms are inclined toward the iron (distances (Å) from
the parent cyclopentadienyl plane: 2a , 0.216(1); 2b,
0.286(1); 7. 0.187(1)) while C1-C11 is bent outward the
ferrocene unit (distances (Å) for C11: 2a , 0.124(2); 2b,
0.169(2); 7, 0.161(2)). Hence, the C1-C11 and C(6)-P
bonds are tilted from the planes of their cyclopenta-
(24) Allen, F. H.; Kennard, O.; Watson, D. G.; Brammer, L.; Orpen,
A. G.; Taylor, R.; J . Chem. Soc., Dalton Trans. 1987, S1.
(25) Zuman, P. Substituent Effects in Organic Polarography; Plenum
Press: New York, 1967; p 47.

2546 Organometallics, Vol. 23, No. 11, 2004
Meca et al.
F igu r e 4. View of the molecular structure of 6‚CHCl3. Thermal motion ellipsoids are drawn at the 30% probability level.
The solvent molecule is not shown.
Ta ble 3. Selected Bon d Dista n ces (Å) a n d An gles
electron wave, whose position changes with Y (E° ) 0.30
V (Y ) OMe), 0.31 V (OEt), and 0.12 V (pyrrolidin-4-yl)
in CH2Cl2). This oxidation has been ascribed to remov-
ing an electron from a molecular orbital which encom-
passes both metal centers.26 On the other hand, the
carbenes all-trans-Fc(CHdCH)nC(OMe)dCr(CO)5 (n )
1-3) show two successive one-electron waves, assigned
by spectroelectrochemical measurements to oxidations
of separate (but electronically communicating) ferrocene
and carbene units.5a
The carbenes 2 exhibit two one-electron redox proc-
esses; the first oxidation is reversible, shifted to mark-
edly lower potentials than in other compounds men-
tioned in this study (E° < 0 V). The second step occurs
approximately 350 mV more positive. This remarkable
negative shift of the first oxidation wave in 2 can be
accounted for by a cooperative influence of the higher
electron-donating ability of NR2 as compared to the OR
group (see E° values for the [FcC(Y)dCr(CO)5] series
above) and an electron density increase resulting from
a replacement of one CO ligand with a phosphine, which
makes the oxidation easier (cf. E° in [CrL(CO)5]:25b L )
CO, E° > 1.2 V; L ) PPh3, E° ) 0.76 V). The latter
assumption is further supported by an observed pKa(CH3)
increase by nearly two orders of magnitude upon
replacement of one carbonyl ligand in the methyl-
carbene species [(OC)5CrdC(Me)OMe] with PPh3, which
points to a higher electron density at chromium and,
consequently, at the methyl group.27
a
(d eg) for 6‚CHCl3
Fe-Cg(1)
W(1)-C(11)
C(1)-C(11)
C(11)-N
1.673(2)
2.284(4)
1.501(5)
1.313(5)
1.480(6)
1.479(5)
Fe-Cg(2)
W(2)-P
P-C(6)
P-C(16)
P-C(22)
1.663(2)
2.545(1)
1.809(4)
1.835(4)
1.830(4)
N-C(12)
N-C(14)
W(1)-C(28)
C(28)-O(1)
W(1)-C(29)
C(29)-O(2)
W(1)-C(30)
C(30)-O(3)
W(1)-C(31)
C(31)-O(4)
W(1)-C(32)
C(32)-O(5)
1.987(5)
1.169(6)
2.045(4)
1.132(5)
2.028(5)
1.142(6)
2.052(4)
1.140(6)
2.070(4)
1.132(5)
W(2)-C(33)
C(33)-O(6)
W(2)-C(34)
C(34)-O(7)
W(2)-C(35)
C(35)-O(8)
W(2)-C(36)
C(36)-O(9)
W(2)-C(37)
C(37)-O(10)
1.997(4)
1.146(5)
2.059(4)
1.131(6)
2.038(5)
1.136(6)
2.038(4)
1.136(5)
2.037(4)
1.139(6)
Cp(1)-Cp(2)
9.2(2)
C(6)-P-C(16)
C(6)-P-C(22)
C(16)-P-C(22)
101.9(2)
103.0(2)
102.3(2)
C(1)-C(11)-N
C(11)-N-C(12)
C(11)-N-C(14)
118.5(3)
125.6(3)
122.4(3)
a
Definitions of the ring planes: Cp(1), C(1-5); Cp(2), C(6-10).
Cg(1) and Cg(2) are the corresponding ring centroids.
ferrocenium). This potential is more positive than for
1, due to a lowered electron density at the ferrocene unit
resulting from coordination of 1 to chromium (the
differences of the first redox potentials for 3 and 1 are
similar: E°(3b) - E°(3a ) ) 30 mV, E°(1b) - E°(1a ) )
20 mV). The second oxidation at 0.88 V is chromium-
centered, which is supported by a comparison with
[Cr(CO)5(Hdpf-κP)],16 where the first wave is shifted
more positively (0.50 V) due to the mentioned substitu-
ent effects, whereas the second oxidation occurs at a
similar potential (+0.85 V).
The question of whether the two oxidation steps
observed for 2 can be assigned to isolated molecular
(26) (a) McCleverty, J . A.; Orchard, D. G.; Connor, J . A.; J ones, E.
M.; Lloyd, J . P.; Rose, P. D. J . Organomet. Chem. 1971, 30, C75. (b)
Lloyd, M. K.; McCleverty, J . A.; Orchard, D. G.; Connor, J . A.; Hall,
M. B.; Hillier, I. H.; J ones, E. M.; McEwen, G. K. J . Chem. Soc., Dalton
Trans. 1973, 1743.
(27) Bernasconi, C. F.; Leyes, A. E.; Ragains, M. L.; Shi, Y.; Wang,
H.; Wulff, W. D. J . Am. Chem. Soc. 1998, 120, 8632.
The redox behavior of 2 cannot be interpreted as
simply as that of 1 and 3. It has been shown that
carbenes [FcC(Y)dCr(CO)5] display a single, one-

Group 6 Aminocarbenes with a Ferrocenyl Substituent
Organometallics, Vol. 23, No. 11, 2004 2547
F igu r e 5. View of the molecular structure of 9 drawn at the 30% probability level. Selected interatomic distances (Å) and
angles (deg): Fe(2)-P ) 2.2505(6), Fe(2)-C(28) ) 1.790(2), C(28)-O(2) ) 1.144(3), Fe(2)-C(29) ) 1.787(2), C(29)-O(3) )
1.155(2), Fe(2)-C(30) ) 1.800(2), C(30)-O(4) ) 1.143(3), Fe(2)-C(31) ) 1.794(2), C(31)-O(5) ) 1.147(3), P-C(6) ) 1.808(2),
P-C(16) ) 1.830(2), P-C(22) ) 1.829(2), C(1)-C(11) ) 1.498(2), N-C(11) ) 1.356(2), C(11)-O(1) ) 1.236(2), N-C(12) )
1.464(3), C(12)-C(13) ) 1.520(3), N-C(14) ) 1.465(2), C(14)-C(15) ) 1.524(3); P-Fe(2)-C(28) ) 177.29(8), P-Fe(2)-
C(29,30,31) ) 87.77(6)-92.08(6), C-P-C ) 102.76(8)-104.31(8), N-C(11)-O(1) ) 121.0(2), C(1)-C(11)-O(1) ) 118.1(2),
C(1)-C(11)-N ) 120.9(2), C(12)-N-C(14) ) 115.3(2), C(11)-N-C(12) ) 126.1(2), C(11)-N-C(14) ) 118.6(2).
Ta ble 4. Electr och em ica l Da ta for Ch r om iu m
chromium carbene complexes 2 with P-chelating phos-
phinoferrocenyl substituents. Formation of carbenes 2
from the amides and [Cr(CO)5]2- salts evenly competes
with the formation of phosphine complexes 3; both
products can be separated from the reaction mixtures
by chromatography. The parallel formation of the phos-
phine complexes from possibly unreacted [Cr(CO)6] in
the efficiently formed carbonylate salt is very unlikely,
since a replacement of one carbonyl ligand in the
carbonyl with Hdpf, the acid parent to the amides 1,
does not proceed willingly (the substitution can be
effected using the labile intermediate [Cr(CO)5(THF)]).16
Com p lexes 1-3a
first wave
second wave
E°
(V)
∆Ep
(mV)
E1/2
(V)
E°
(V)
∆Ep
(mV)
E1/2
(V)
compd
1a
1b
2a
2b
3a
3b
0.20
0.22
-0.13
-0.08
0.33
75
85
60
70
90
80
0.20
0.22
-0.13
-0.07
0.33
0.23
0.27
0.88
0.88
80
120
100
100
b
b
0.88
0.89
0.36
0.36
a
The potentials are given relative to internal ferrocene/ferro-
cenium. E° is the redox potential from cyclic voltammetry, defined
as E° ) 1/2(Epa + Epc), while ∆Ep denotes the separation of the
cyclic voltammetric peaks: ∆Ep ) Ep,a - Ep,c. Ep,a and Ep,c are the
anodic and cathodic peak potentials, respectively. E1/2 is the half-
A similar synthesis of the tungsten analogues is much
less satisfactory, due to a more complicated reaction
sequence and lower yields, and not feasible at all for
the reaction of [Fe(CO)4]2- with 1a , since the side
reaction prevails, giving the phosphine carbonyl complex
9 as the only isolated product.
b
wave potential, determined by voltammetry. Not read; the vol-
tammetric wave is tilted.
parts or are two successive oxidations of the whole
molecular system remains unaddressed. The latter
alternative seems to be more likely, considering the
conjugated nature of these compounds and rather large
separations of the metal center (2a , 4.0828(4) Å; 4b ,
4.0876(4) Å; 7, 4.1945(4) Å; cf. Fe-W1 ) 5.2323(6) Å
and Fe-W2 ) 5.0188(6) Å for 5), which rule out direct
metal-metal bonding but not an electrostatic interac-
tion.
P-chelated carbenes 2 are most likely formed in a
stepwise manner by a sequence of the carbene-forming
reaction and a subsequent intramolecular substitution
of one CO ligand, as suggested for the alkoxy analogues
II.8 Strong support for this mechanism comes from the
reactions of kinetically more stable tungsten analogues,
where the anticipated intermediate, the simple carbene
5, was characterized and further converted to 7. Forma-
tion of the chelated carbenes from nonchelated precur-
sors cannot be simply reversed; carbenes 2 and 7 do not
react in solution with CO gas (1 atm). As indicated by
Con clu sion
Phosphinoamides 1 are valuable building blocks for
organometallic synthesis, allowing access to unique

2548 Organometallics, Vol. 23, No. 11, 2004
Meca et al.
Mor p h olid e 1b. Amide 1b was obtained by a similar
protocol, starting with Hdpf10 (1.243 g, 3.00 mmol), 1-hydroxy-
benzotriazole (0.446 g, 3.3 mmol), N-(3-(dimethylamino)-
propyl)-N′-ethylcarbodiimide (0.512 g, 3.3 mmol), and mor-
pholine (0.30 mL, 3.44 mmol) in dichloromethane (50 mL).
Yield: 1.434 g (99%) of an orange-red oil which solidifies upon
standing.
electrochemical measurements, carbenes 2 are an ex-
ample of the cooperative effect of the metal center
enhanced by a conjugated bridge.
Exp er im en ta l Section
Ch em ica ls a n d Meth od s. All syntheses were carried out
under argon with the exclusion of direct sunlight. Dichloro-
methane used in the syntheses was dried over potassium
carbonate. THF and toluene were freshly distilled from
sodium-benzophenone ketyl. Diethylamine and morpholine
were distilled from sodium under argon. Other chemicals were
prepared by the literature procedures (see below) or used as
received from commercial suppliers.
NMR spectra were recorded on a Varian UNITY Inova 400
spectrometer at 399.95 (1H), 100.58 (13C), and 161.90 MHz
(31P). Chemical shifts (δ/ppm) are referenced to internal
tetramethylsilane (1H, 13C) and external 85% aqueous H3PO4
(31P). IR spectra were recorded on either a Nicolet 740 or a
Nicolet Magna FT IR spectrometer. Mass spectra were meas-
ured using an Autospec Ultima or a ZAB-SEQ VG analytical
spectrometer operating in positive-ion electron impact (EI) or
fast atom bombardment (FAB) modes.
Electrochemical measurements were carried out with a
multipurpose PA3 polarograph interfaced to a Model 4103 XY
recorder (Laboratorn´ı prˇ´ıstroje, Prague, Czech Republic) at
room temperature using a standard three-electrode system:
platinum-disk working electrode, platinum-wire auxiliary
electrode, and Ag/AgCl (1 M KCl) reference electrode. The
analyzed solutions contained a ca. 4 × 10-4 M concentration
of the analyte and 0.1 M Bu4NPF6 (Fluka, purissimum for
electrochemistry) as the supporting electrolyte in dichloro-
methane (Merck p.a., used without further purification). Prior
to the measurement, the solutions were purged with argon and
kept under an argon blanket. Cyclic voltammograms were
recorded on a stationary disk electrode (scan rate 100 mV s-1),
while the voltammograms were measured with a rotating
electrode (1000 min-1, scan rate 20 mV s-1). The potentials
are given in volts relative to the redox potential of the
ferrocene/ferrocenium standard.
1H NMR (CDCl3): δ 3.60-3.68 (m, 8 H, NCH2CH2O); 4.15
(apparent q, 2 H, CH, fc); 4.21, 4.36, 4.49 (3 × apparent t, 2
H, CH, fc); 7.29-7.38 (m, 10 H, PPh2). 13C{1H} NMR (CDCl3):
δ ∼45 (very br, NCH2); 66.93 (OCH2); 70.73, 71.17, 73.56 (d,
J PC ) 4 Hz), 74.31 (d, J PC ) 14 Hz) (4 × CH, fc); 79.00 (Cipso
,
fc); 128.21 (d, J PC ) 7 Hz), 128.65, 133.44 (d, J PC ) 19 Hz) (3
× CH, PPh2); 133.49 (d, 1J PC ) 9 Hz, Cipso, PPh2); 169.12 (CdO);
the other Cipso(fc) was not found. 31P{1H} NMR (CDCl3): δ
-16.9 (s). IR (Nujol): ν/cm-1
ν
CdO 1612 (vs), 1605 (vs). HR MS
(EI): calcd for C27H2656FeNO2P (M+), 483.1051; found, 483.1002.
Syn th esis of [(Dieth yla m in o){1′-(d ip h en ylp h os-
p h in o-KP )fer r ocen yl}m et h ylid en e-KC1]t et r a ca r b on yl-
ch r om iu m (0) (2a ) a n d [N,N-Dieth yl-1′-(d ip h en ylp h os-
p h in o-KP )fer r ocen eca r b oxa m id e]p en t a ca r b on ylch r o-
m iu m (0) (3a ). A solution of sodium naphthalenide, prepared
by stirring sodium metal (48 mg, 2.1 mmol) and naphthalene
(272 mg, 2.1 mmol) in anhydrous THF (5 mL) at room
temperature until all the metal dissolved, was added at -78
°C via a syringe into a solution of chromium hexacarbonyl (176
mg, 0.8 mmol) in the same solvent (5 mL). The reaction
mixture was warmed to 0 °C, stirred for 30 min, and cooled to
-78 °C. Amide 1a (328 mg, 0.7 mmol) in THF (2 mL) was
added to the solution of carbonylate salt Na2[Cr(CO)5], and
the mixture was warmed to 0 °C and stirred at this temper-
ature for 30 min. Then, it was recooled to -78 °C and treated
with trimethylchlorosilane (0.2 mL, 1.6 mmol). After the
mixture was stirred at -78 °C for another 30 min, the cooling
bath was removed and the reaction mixture was brought to
room temperature for 1 h with stirring and mixed with neutral
alumina (1 g). The solvent was removed under vacuum and
the residue carefully dried under vacuum of an oil pump to
remove all volatiles. The solid residue was mixed with light
petroleum (2 mL) and the suspension transferred to a chro-
matographic column filled with neutral alumina (15 g).
Naphthalene was removed with hexane. A subsequent suc-
cessive elution with hexane-dichloromethane (1:1) and di-
chloromethane afforded respectively carbene 2a (bright orange
solid; 200 mg, 46%) and the phosphine complex 3a (orange
waxy solid; 172 mg, 37%).
P r epar ation of Am ides 1. N,N-Dieth yl-1′-(diph en ylph os-
p h in o)fer r ocen eca r boxa m id e (1a ). To an ice-cooled solution
of Hpdf10 (2.072 g, 5.00 mmol) in dry dichloromethane (75 mL)
was added 1-hydroxybenzotriazole (0.748 g, 5.5 mmol) and
N-(3-(dimethylamino)propyl)-N′-ethylcarbodiimide (0.861 g, 5.5
mmol). The mixture was stirred at 0 °C for 1 h; the triazole
quickly dissolved. Neat diethylamine (0.64 mL, 6.2 mmol) was
added, the cooling bath was removed, and stirring was
continued at room temperature overnight. The reaction mix-
ture was extracted with 3 M HCl, saturated aqueous NaHCO3,
and water, and the organic phase was dried (MgSO4) and
evaporated. The residue was purified by flash chromatography
on silica gel using dichloromethane-methanol (10:1) as the
eluent. Evaporation (at 60 °C/0.3 Torr for 30 min) yielded a
red-orange oil which solidified upon standing at room tem-
perature to give a rusty brown amorphous solid. Yield: 2.141
g (91%).
1
Analytical data for 2a are as follows. H NMR (CDCl3): δ
3
3
1.00, 1.61 (2 × t, J HH ) 7.2 Hz, 3 H, Me); 3.45 (q, J HH ) 7.2
Hz, 2 H, NCH2); 4.14 (apparent t, 2 H), 4.18 (br s, 2 H), 4.35
(br apparent t, 2 H), 4.41 (br s, 2 H) (4 × CH, fc); 4.84 (q, 3J HH
) 7.2 Hz, 2 H, NCH2); 7.31-4.78 (m, 10 H, PPh2). 13C{1H}
NMR (CDCl3): δ 13.98, 14.26 (Me); 46.67, 56.91 (NCH2); 67.48,
67.83 (br), 71.63 (br d, J PC ≈ 5 Hz), 76.88 (d, J PC ) 10 Hz) (4
1
3
× CH, fc); 84.13 (d, J PC ) 34 Hz, CP, fc); 109.24 (d, J PC ) 5
Hz, CCdCr, fc); 127.73 (d, J PC ) 9 Hz), 129.37 (d, J PC ≈ 1 Hz),
1
133.17 (d, J PC ) 11 Hz) (3 × CH, PPh2); 137.90 (d, J PC ) 32
2
2
Hz, Cipso, PPh2); 221.63 (d, J PC ) 15 Hz), 227.33 (d, J PC ) 10
Hz), 227.89 (3 × CtO); 279.21 (d, 2J PC ) 13 Hz, CdCr). 31P{1H}
NMR (CDCl3): δ 58.1 (s). IR (CHCl3): ν/cm-1 νCtO 1993 vs,
1897 s, 1871 br vs. MS (EI): m/z 589 ([M - CO]+), 505 ([M -
4 CO]+), 476 ([M - CO - C2H5]+), 434 ([M - 4 CO - NC4H9]+).
Anal. Calcd for C31H28CrFeNO4P‚2/3CH2Cl2: C, 56.43; H, 4.39;
N, 2.08. Found: C, 56.42; H, 4.54; N, 1.91 (the complex tends
to retain solvent in the structure upon recrystallization from
dichloromethane; the solvent content was verified by 1H NMR).
3
1H NMR (CDCl3): δ 1.16 (t, J HH ) 7.1 Hz, 6 H, Me); 3.44
(br q, 3J HH ≈ 7 Hz, 4 H, NCH2); 4.15 (apparent q, 2 H, CH, fc);
4.18, 4.46, 4.51 (3 × apparent t, 2 H, CH, fc); 7.28-7.39 (m,
10 H, PPh2). 13C{1H} NMR (CDCl3): δ 0.13.7 (br, Me); ∼41.7
(br, NCH2); 70.89, 71.09, 73.74 (br d, J PC ≈ 4 Hz), 74.11 (d,
J PC ) 14 Hz) (4 × CH, fc); 79.71 (Cipso, fc); 128.20 (d, J PC ) 7
Hz), 128.70, 133.43 (d, J PC ) 19 Hz) (3 × CH, PPh2); ∼133.8
(br, Cipso, PPh2); 169.05 (CdO); the second Cipso(fc) resonance
is probably obscured by the solvent signal. 31P{1H} NMR
(CDCl3): δ -16.8 (s). IR (Nujol): ν/cm-1 νCdO 1629 (vs), 1620
(vs). HR MS (EI): calcd for C27H2856FeNOP (M+), 469.1258;
found, 469.1276. Anal. Calcd for C27H28FeNOP: C, 69.10; H,
6.01; N, 2.98. Found: C, 69.01; H, 6.23; N, 3.10.
1
Analytical data for 3a are as follows. H NMR (CDCl3): δ
1.11 (br s, 6 H, Me); 3.35 (br s, 4 H, CH2); 4.03 (apparent t, 2
H), 4.34 (apparent t, 2 H), 4.36 (apparent q, 2 H), 4.60 (br
apparent t, 2 H) (4 × CH, fc); 7.39-7.50 (m, 10 H, PPh2).
13C{1H} NMR (CDCl3): δ 12.79, 14.63 (br, Me); 40.65, 42.65
(CH2); 71.11, 71.13, 74.67 (d, J PC ) 11 Hz), 74.90 (d, J PC ) 11

Group 6 Aminocarbenes with a Ferrocenyl Substituent
Organometallics, Vol. 23, No. 11, 2004 2549
1
Hz) (4 × CH, fc); 79.89 (d, J PC ) 39 Hz, CP, fc); 81.32 (C-
finally, dichloromethane eluted [W(CO)5{Ph2PfcCHO-κP}] (8;
red-orange oil; 37 mg, 3%).
CO, fc); 128.15 (d, J PC ) 9 Hz), 128.94 (d, J PC ) 2 Hz), 132.28
(d, J PC ) 11 Hz) (3 × CH, PPh2); 137.82 (d, 1J PC ) 39 Hz, Cipso
,
Analytical data for [N,N-diethyl-1′-(diphenylphosphino-κP)-
ferrocenecarboxamide]pentacarbonyltungsten(0) (4) are as fol-
PPh2), 168.37 (CdO), 216.74 (d, 2J PC ) 13 Hz), 221.28 (d, 2J PC
) 7 Hz) (2 × CtO). 31P{1H} NMR (CDCl3): δ 47.3 (s). IR
(CHCl3): ν/cm-1 νCtO 2063 s, 1984 m, 1939 br vs; νCdO 1614
m. MS (EI): m/z 661 (M+), 521 ([M - 5 CO]+), 469 ([Ph2PfcC-
(O)NEt2]+). HR MS (EI): calcd for C27H2852Cr56FeNOP ([M -
5 CO]+), 521.0663; found, 521.0657.
1
lows. H NMR (CDCl3): δ 1.10 (br s, 6 H, Me); 3.34 (br s, 4 H,
CH2); 4.06 (apparent t, 2 H), 4.34-4.37 (m, 4 H), 4.63 (d of
apparent t, 2 H) (4 × CH, fc); 7.39-7.48 (m, 10 H, PPh2).
13C{1H} NMR (CDCl3): δ 12.81, 14.62 (br, Me); 40.63, 42.62
(CH2); 71.01, 71.08, 74.91 (d, J PC ) 12 Hz), 75.18 (d, J PC ) 7
1
Syn th esis of [(4-Mor p h olin yl){1′-(d ip h en ylp h osp h in o-
KP )fer r ocen yl}m et h ylid en e-KC1]-t et r a ca r b on ylch r om i-
u m (0) (2b) a n d [1′-(Dip h en ylp h osp h in o-KP )fer r ocen e-
ca r boxylic a cid m or p h olid e]p en ta ca r bon ylch r om iu m (0)
(3b). With morpholide 1b as starting material (338 mg, 0.7
mmol), the same procedure as above afforded a mixture of
morpholide complexes 2b and 3b. Chromatography on alumina
with hexane-dichloromethane (1:1) as the eluent gave a small
amount of colored byproducts, immediately followed by 2b
(bright orange solid; 85 mg, 19%). Further elution with
dichloromethane yielded 3b as an orange solid (182 mg, 38%).
Hz) (4 × CH, fc); 79.31 (d, J PC ) 45 Hz, CP, fc), 81.41 (C-
CO, fc), 128.15 (d, J PC ) 9 Hz), 130.00 (d, J PC ) 2 Hz), 132.42
(d, J PC ) 12 Hz) (3 × CH, PPh2); 137.76 (d, 1J PC ) 44 Hz, Cipso
,
2
PPh2), 168.32 (CdO), 197.28 (d, J PC ) 13 Hz, 183W satellites,
2
2J WC ) 126 Hz), 198.77 (d, J PC ) 21 Hz) (2 × CtO). 31P{1H}
1
NMR (CDCl3): δ 11.2 (s; 183W satellites, J WP ) 246 Hz). IR
(CHCl3): ν/cm-1 νCtO 2071 s, 1982 m, 1982 vs, 1738 m; νCdO
1613 m. MS (EI): m/z 793 (M+), 709 ([M - 3 CO]+), 651 ([M -
5 CO]+), 469 ([Ph2PfcC(O)NEt2]+). HR MS (EI): calcd for
C29H2856FeNO3P184W ([M - 3 CO]+), 709.0666; found, 709.0659.
Analytical data for [(diethylamino){1′-(diphenylphosphino)-
ferrocenyl}methylidene-κC1]pentacarbonyltungsten(0) (5) are
as follows. This compound could not be isolated in pure form.
NMR data have been obtained by a subtraction of signals due
to 6 from the spectra of the above mixture of 5 and 6. 1H NMR
1
Analytical data for 2b are as follows. H NMR (CDCl3): δ
3.48 (m, 2 H, CH2); 3.64 (m, 2 H, CH2); 4.13 (br s, 2 H, CH, fc);
4.15-4.19 (m, 4 H, CH2 and CH(fc)); 4.37, 4.72 (2 × br s, 2 H,
CH, fc); 4.99 (m, 2 H, CH2); 7.33-7.48 (m, 10 H, PPh2). 13C{1H}
NMR (CDCl3): δ 55.30 (CH2); 62.58 (CH2); 67.74 (CH2); 67.97
(CH, fc); 68.33 (CH2); 71.85 (br, CH, fc); 76.86 (d, J PC ) 10 Hz,
CH, fc); 84.17 (d, 1J PC ) 34 Hz, CP, fc); 108.30 (d, 3J PC ) 5 Hz,
CCdCr, fc); 127.84 (d, J PC ) 9 Hz); 129.51 (d, J PC ≈ 2 Hz);
3
(CDCl3): δ 1.34, 1.41 (2 × t, J HH ) 7.2 Hz, 3 H, Me); 4.00
(apparent q, 2 H, fc); 4.25 (q, 3J HH ) 7.2 Hz, 2 H, NCH2), 4.29,
3
4.39, 4.40 (3 × apparent t, 2 H, fc); 4.80 (q, J HH ) 7.2 Hz, 2
H, NCH2); 7.31-7.47 (m, 10 H, PPh2). 13C{1H} NMR (CDCl3):
δ 14.40, 15.29 (Me); 45.77, 58.28 (NCH2); 70.85, 71.19, 72.47
(d, J PC ) 3 Hz), 74.17 (d, J PC ) 14 Hz) (4 × CH, fc); 78.34 (d,
1J PC ) 8 Hz, CP, fc); 97.69 (CCdCr, fc); 128.30 (d, J PC ≈ 10
Hz), 128.76, 133.40 (d, J PC ) 19 Hz) (3 × CH, PPh2); 138.12
1
133.10 (d, J PC ) 11 Hz) (3 × CH, PPh2); 137.75 (d, J PC ) 32
2
2
Hz, Cipso, PPh2); 221.86 (d, J PC ) 15 Hz), 227.03 (d, J PC ) 9
2
Hz), 228.15 (3 × CtO); 280.46 (d, J PC ) 13 Hz, CdCr); one
CH(fc) probably overlapped by the solvent signal. 31P{1H}
NMR (CDCl3): δ 58.5 (s). IR (CHCl3): ν/cm-1 νCtO 1994 vs,
1939 m, 1900 m, 1873 br vs. MS (EI): m/z 603 ([M - CO]+),
519 ([M - 4 CO]+), 434 ([M - 4 CO - C4H7NO]+). Anal. Calcd
for C32H26FeNO6P: C, 58.97; H, 4.15; N, 2.22. Found: C, 58.50;
H, 4.13; N, 2.09.
1
(d, J PC ) 10 Hz, Cipso, PPh2), 198.96 (s with 183W satellites,
1J WC. 114 Hz), 204.09 (2 × CdW(CO)5), 251.04 (WdC).
31P{1H} NMR (CDCl3): δ -18.2 (s). HR MS (FAB): calcd for
C30H2856FeNO3P184W ([M - 2 CO]+), 721.0666; found, 721.0673.
Analytical data for [(diethylamino){1′-(diphenylphosphino-2κP)-
ferrocenyl}methylidene-1κC1]bis[pentacarbonyltungsten(0)]
1
Analytical data for 3b are as follows. H NMR (CDCl3): δ
1
3
3.55, 3.59 (2 × br s, 4 H, CH2); 4.02 (apparent t, 2 H); 4.28
(apparent t, 2 H), 4.36 (apparent q, 2 H), 4.64 (dt, J ≈ 0.8, 1.9
Hz, 2 H) (4 × CH, fc); 7.40-7.49 (m, 10 H, PPh2). 13C{1H} NMR
(CDCl3): δ ∼43.3, ∼47.0 (v br, CH2); 66.79 (CH2); 71.24, 71.00,
74.84 (d, J PC ) 7 Hz), 74.89 (d, J PC ) 11 Hz) (4 × CH, fc);
(6) are as follows. H NMR (CDCl3): δ 1.32, 1.42 (2 × t, J HH
) 7.1 Hz, 3 H, Me); 4.19 (s, 4 H, fc); 4.22 (apparent q, 2 H, fc);
4.26 (q, 3J HH ) 7.1 Hz, 2 H, NCH2); 4.54 (apparent dt, 2 H, fc);
4.71 (q, 3J HH ) 7.1 Hz, 2 H, NCH2); 7.38-7.47 (m, 10 H, PPh2).
13C{1H} NMR (CDCl3): δ 14.33, 15.22 (Me); 45.48, 58.32
(NCH2); 71.00, 71.15, 73.77 (d, J PC ) 7 Hz), 74.66 (d, J PC ) 11
Hz) (4 × CH, fc); 80.80 (d, 1J PC ) 43 Hz, CP, fc); 98.37 (CCdCr,
fc); 128.30 (d, J PC ) 10 Hz), 130.27 (d, J PC ) 2 Hz), 132.38
1
80.45 (d, J PC ) 38 Hz, CP, fc); 80.48 (C-CO, fc); 128.17 (d,
J PC ) 10 Hz), 129.86 (d, J PC ) 2 Hz), 132.25 (d, J PC ) 11 Hz)
1
(3 × CH, PPh2); 137.82 (d, J PC ) 39 Hz, Cipso, PPh2), 168.34
2
2
1
(CdO), 216.70 (d, J PC ) 13 Hz), 221.19 (d, J PC ) 7 Hz)
(2 × CtO). 31P{1H} NMR (CDCl3): δ 47.3 (s). IR (CHCl3):
ν/cm-1 νCtO 2063 s, 1984 m, 1939 br vs; νCdO 1623 m. MS
(EI): m/z 675 (M+), 563 ([M - 4 CO]+), 535 ([M - 5 CO]+),
483 ([Ph2PfcC(O)N(CH2CH2)O]+). HR MS (EI): calcd for
(d, J PC ) 12 Hz) (3 × CH, PPh2); 137.35 (d, J PC ) 44 Hz,
2
1
C
ipso, PPh2); 197.14 (d, J PC ) 7 Hz with 183W satellites, J WC
2
) 126 Hz), 198.47 (d, J PC ) 21 Hz) (2 × PW(CO)5); 198.82
(s with 183W satellites, J WC ) 128 Hz), 203.88 (s with
1
183W satellites, 1J WC ) 127 Hz) (2 × CdW(CO)5); 250.86 (s with
32H2652Cr56FeNO7P (M•+), 675.0203; found, 675.0206. HR MS
183W satellites, J WC. 90 Hz, WdC). 31P{1H} NMR (CDCl3): δ
1
C
(EI): calcd for C27H2652Cr56FeNO2P ([M - 5 CO]+), 535.0456;
found, 535.0439.
11.0 (s; 183W satellites, J WP ) 247 Hz). IR (CHCl3): ν/cm-1
1
νCtO 2072 s, 2060 s, 1928 br vs. HR MS (FAB): calcd for
C32H2856FeNO5P184W2 ([M - 5 CO]+), 961.0074; found, 961.0091.
Analytical data for [(diethylamino){1′-(diphenylphosphino-
κP)ferrocenyl}methylidene-κC1]tetracarbonyltungsten(0) (7) are
P r ep a r a tion of Tu n gsten Com p lexes. With tungsten
hexacarbonyl (564 mg, 1.6 mmol) and 1a (656 mg, 1.4 mmol)
as starting materials, the above method gave a red-orange
solid which was purified by chromatography on alumina.
Elution with a hexane-dichloromethane mixture (2:1) gave a
mixture of 5 and 6 (bright red solid, 125 mg). A further elution
with dichloromethane afforded
[W(CO)5{Ph2PfcC(O)NEt2-κP}] (4) (orange waxy solid; 585 mg,
53%).
The mixture containing 5 and 6 was dissolved in toluene
(125 mg in 1 mL) and the solution heated to 80 °C for 4 h. The
solvent was removed under reduced pressure and the residue
purified by chromatography on silica gel (50 g). Elution with
a hexane-dichloromethane mixture (2:1) afforded unchanged
6 (red foam; 29 mg, 2%), subsequent elution with hexane-
dichloromethane (1:1) gave the carbene [W(CO)4{Ph2PfcC-
(NEt)2-κ2C1,P}] (7; bright orange crystals; 46 mg, 4%), and,
3
as follows. 1H NMR (CDCl3): δ 1.03, 1.55 (2 × t, J HH ) 7.2
3
Hz, 3 H, Me); 3.44 (q, J HH ) 7.2 Hz, 2 H, NCH2); 4.18 (br m,
3
4 H), 4.37 (s, 4 H) (4 × CH, fc); 4.70 (q, J HH ) 7.2 Hz, 2 H,
NCH2); 7.31-7.48 (m, 10 H, PPh2). 13C{1H} NMR (CDCl3): δ
13.91, 14.01 (Me); 46.54, 59.55 (NCH2); 67.46, 67.86 (br), 71.55
(br d, J PC ≈ 6 Hz), ca. 76.7 (d, J PC ≈ 12 Hz) (4 × CH, fc); 84.10
a well-separated band of
1
3
(d, J PC ) 42 Hz, CP, fc); 109.50 (d, J PC ) 5 Hz, CCdW, fc);
127.80 (d, J PC ) 9 Hz), 129.61 (d, J PC ) 2 Hz), 133.43 (d, J PC
) 12 Hz) (3 × CH, PPh2); 137.40 (d, 1J PC ) 38 Hz, Cipso, PPh2);
2
2
204.94 (d, J PC ) 7 Hz), 209.06 (d, J PC ) 31 Hz), 209.86 (d,
2J PC ) 4 Hz) (3 × CtO); 260.64 (d, 2J PC ) 9 Hz, CdW). 31P{1H}
NMR (CDCl3): δ 27.9 (s; 183W satellites, J WP ) 249 Hz). IR
1
(CHCl3): ν/cm-1 νCtO 2001 vs, 1894 s, 1872 br vs. MS (EI):
m/z 749 (M+), 721 ([M - CO]+), 693 ([M - 2 CO]+), 665 ([M -

2550 Organometallics, Vol. 23, No. 11, 2004
Meca et al.
Ta ble 5. Cr ysta llogr a p h ic Da ta a n d Da ta Collection a n d Stu ctu r e Refin em en t Deta ils for 2a ‚CH2Cl2, 2b,
6‚CHCl3, 7, a n d 9
2a ‚CH2Cl2
2b
6‚CHCl3
7
9
formula
mol wt
cryst syst
space group
a (Å)
C
32H28Cl2CrFeNO4Pc
C
31H26CrFeNO5P
C38H29Cl3FeNO10PW2
1220.49
monoclinic
P21/n (No. 14)
13.7968(2)
9.1526(1)
33.1824(3)
90
90.5776(7)
90
4189.95(8)
4
C31H28FeNO4PW C31H28Fe2NO5P
700.27
631.35
749.21
637.21
monoclinic
P21/n (No. 14)
10.0026(1)
16.9132(2)
18.5294(2)
90
98.0621(6)
90
3103.75(6)
4
1.499
1.079
13 927
7094/6189
390
triclinic
P1h (No. 2)
9.1250(1)
9.2763(1)
17.0026(3)
76.4486(8)
77.4729(8)
82.9206(7)
1361.85(3)
2
1.540
1.033
11 540
6212/5224
361
monoclinic
Cc (No. 9)f
9.9709(1)
19.0932(3)
15.1138(3)
90
monoclinic
P21/n (No. 14)
15.0963(2)
8.4394(1)
23.0502(3)
90
b (Å)
c (Å)
R (deg)
â (deg)
γ (deg)
V (Å3)
Z
92.778(1)
90
106.5920(5)
90
2873.93(8)
4
2814.40(6)
4
Dc (g cm-3
)
1.935
1.732
1.504
1.129
µ(Mo KR) (mm-1
)
6.104e
4.596g
total no. of diffrns
no. of unique/obsda diffrns
no. of params
52 703
9567/8125
507
2.86
6.90, 6.37
1.28, -1.45
21 249
12 434
6337/6253
354
6441/4977
363
R (obsd diffrns) (%)b
R, Rw (all data) (%)b
3.58
2.93
3.95, 6.92
0.35, -0.57
1.71
3.27
4.26, 9.90
3.81, 3.78
0.50, -0.75
5.08, 7.93
0.34, -0.44
∆F (e Å-3
)
1.07, -1.09d
Diffractions with Io > 2σ(Io). R(F) ) ∑||Fo| - |Fc||/∑|Fo|; Rw(F2) ) [∑{w(Fo - Fc2)2}/∑w(Fo2)2]1/2
.
c The solvate was refined without
a
b
2
d
hydrogen atoms (see Experimental Section). Residual electron density in the space accommodating the disordered solvate molecules.
g
e Corrected for absorption; transmission coefficient range 0.160-0.619. f Flack’s enantiomorph parameter: -0.015(4). Corrected for
absorption; transmission coefficient range 0.231-0.506.
3 CO]+), 637 ([M - 4 CO]+), 370 (FcPPh2)+. Anal. Calcd for
31H28FeNO4PW: C, 49.70; H, 3.77; N, 1.87. Found: C, 49.69;
H, 3.73; N, 1.77.
1H NMR (CDCl3): δ 1.10, 1.12 (2 × br s, 3 H, Me); 3.30,
3.37 (2 × br s, 2 H, CH2); 3.69 (apparent t, 2 H), 4.24 (apparent
t, 2 H), 4.61-4.65 (m, 4 H) (4 × CH, fc); 7.39-7.59 (m, 10 H,
PPh2). 13C{1H} NMR (CDCl3): δ 12.81, 14.63 (br, Me); 40.71,
42.64 (CH2); 71.11, 71.53, 75.04 (d, J PC ) 10 Hz), 75.93 (d, J PC
C
Analytical data for [1′-(diphenylphosphino-κP)ferrocene-
carboxaldehyde]pentacarbonyltungsten(0) (8) are as follows.
1H NMR (CDCl3): δ 4.38-4.41 (m, 4 H), 4.58 (apparent t, 2
H), 4.64 (apparent dt, 2 H) (4 × CH, fc); 7.40-7.48 (m, 10 H,
PPh2), 9.43 (s, 1 H, CHO). 13C{1H} NMR (CDCl3): δ 70.79,
73.19 (d, J PC ) 7 Hz), 74.71, 74.97 (d, J PC ) 12 Hz) (4 × CH,
1
) 11 Hz) (4 × CH, fc); 77.09 (d, J PC ≈ 50 Hz, CP, fc; partly
obscured by the solvent signal); 81.50 (C-CO, fc); 128.16 (d,
J PC ) 10 Hz), 130.44 (d, J PC ) 2 Hz), 132.49 (d, J PC ) 10 Hz)
1
(3 × CH, PPh2); 137.58 (d, J PC ) 52 Hz, Cipso, PPh2), 168.43
1
2
fc); 79.74 (C-CHO, fc); 80.99 (d, J PC ) 43 Hz, CP, fc); 128.37
(CdO), 213.20 (d, J PC ) 19 Hz) (CtO). 31P{1H} NMR
(d, J PC ) 10 Hz), 130.31 (d, J PC ) 2 Hz), 132.41 (d, J PC ) 12
(CDCl3): δ 66.9 (s). IR (CHCl3): ν/cm-1 νCtO 2049 vs, 1975 s,
1941 vs; νCdO 1615 m. MS: m/z 603 ([M - CO]+), 581 ([M - 2
CO]+), 553 ([M - 3 CO]+), 525 ([M - 4 CO]+), 469 ([Ph2PfcC-
(O)NEt2]+). HR MS (EI): calcd for C32H2852Cr56FeNO6P ([M -
3 CO]+), 553.0556; found, 553.0550.
Hz) (3 × CH, PPh2); 137.46 (d, 1J PC ) 44 Hz, Cipso, PPh2); 193.21
2
2
(CdO), 197.12 (d, J PC ) 7 Hz), 198.45 (d, J PC ) 22 Hz) (2 ×
CtO). 31P{1H} NMR (CDCl3): δ 11.1 (s; 183W satellites, J WP
1
) 247 Hz). IR (CHCl3): ν/cm-1 νCtO 2072 s, 1984 m, 1937 br
vs; νCdO 1684 m, 1665 m. MS (EI): m/z 722 (M+), 694 ([M -
CO]+), 666 ([M - 2 CO]+), 638 ([M - 3 CO]+), 610 ([M - 4
CO]+), 582 ([M - 5 CO]+).
X-r a y Cr ysta llogr a p h y. X-ray-quality crystals were ob-
tained by diffusion of pentane into a dichloromethane solution
(2a ‚CH2Cl2, red prism, 0.28 × 0.28 × 0.35 mm3) or similarly
from pentane/CHCl3 (2b, red-orange plate, 0.08 × 0.20 × 0.53
mm3) and hexane/CHCl3 (6‚CHCl3, red plate, 0.09 × 0.15 ×
0.35 mm3; 7, orange prism, 0.15 × 0.35 × 0.40 mm3; 9, red
plate, 0.08 × 0.10 × 0.30 mm3). Full-set diffraction data
((h,(k,(l) with 2θ e 55.0° for all compounds were collected
Rea ction s of 2a a n d 7 w ith Ca r bon Mon oxid e. A
solution of carbene in CDCl3 (2a , 20 mg/1 mL; 7, 8.5 mg/1 mL)
was stirred under CO (1 atm) at room temperature for 1 day.
The solution was filtered trough a 0.45 µm PTFE syringe filter
1
and immediately analyzed by H and 31P NMR spectroscopy.
In both cases the spectra revealed only unchanged carbenes.
Syn th esis of [N,N-Dieth yl-1′-(d ip h en ylp h osp h in o-KP )-
fer r ocen eca r boxa m id e]tetr a ca r bon ylir on (0), [F e(CO)4-
{P h 2P fcC(O)NEt2-KP }] (9). A solution of sodium naphtha-
lenide prepared as above from sodium (72 mg, 3.1 mmol) and
naphthalene (408 mg, 3.2 mmol) in THF (6 mL) was added
via a syringe into a solution of iron pentacarbonyl (0.16 mL,
0.8 mmol) in THF (6 mL) at -78 °C. The reaction mixture was
warmed to 0 °C, stirred at this temperature for 30 min, cooled
to -78 °C, and treated with a solution of 1a (328 mg, 0.7 mmol)
in THF (2 mL). The mixture was warmed to 0 °C, stirred for
30 min at 0 °C, and then cooled to -78 °C. Trimethylchloro-
silane (0.3 mL, 2.4 mmol) was added and the solution stirred
at -78 °C for another 30 min. The cooling bath was removed,
and the mixture was stirred for 1 h without external cooling.
Then, neutral alumina (1 g) was added, THF was removed
under reduced pressure, and the residue was dried under high
vacuum to remove all volatiles. The residue was mixed with
light petroleum (2 mL) and the suspension transferred onto a
column filled with neutral alumina (15 g). Naphthalene was
eluted with hexane. A subsequent elution with dichloro-
methane gave 9 as an orange solid (250 mg, 56%).
on a Nonius KappaCCD diffractometer equipped with a
Cryostream cooler (Oxford Crysoystems) at 150 K using
graphite-monochromated Mo KR radiation (λ ) 0.710 73 Å)
and analyzed with the HKL program package.27
The structures were solved by direct methods (SIR9228
)
and refined by weighted full-matrix least squares on F2
(SHELXL9729). Final geometric calculations were carried out
with a recent version of the Platon program.30 All non-
hydrogen atoms were refined with anisotropic thermal motion
parameters. The hydrogen atoms were included in the theo-
retical positions (C-H bond lengths: 0.93 (aromatic), 0.97
(methylene) and 0.96 (methyl) C) and assigned Uiso(H) )
(28) Otwinowski, Z.; Minor, W. HKL Denzo and Scalepack program
package by Nonius BV, Delft, The Netherlands, 1997. For a reference
see: Otwinowski, Z.; Minor, W. Methods Enzymol. 1997, 276, 307.
(29) Altomare, A.; Burla, M. C.; Camalli, M.; Cascarano, G.; Giaco-
vazzo, C.; Guagliardi, A.; Polidori, G. J . Appl. Crystallogr. 1994, 27,
435.
(30) Sheldrick, G. M. SHELXL97. Program for Crystal Structure
Refinement from Diffraction Data; University of Go¨ttingen, Go¨ttingen,
Germany, 1997.
(31) Spek, A. L. Platon-A Multipurpose Crystallographic Tool, 2001;
available at http://www.cryst.chem.uu.nl/platon/.

Group 6 Aminocarbenes with a Ferrocenyl Substituent
Organometallics, Vol. 23, No. 11, 2004 2551
1.2[Ueq(C)] (aromatic and methylene) or 1.5[Ueq(C)] (methyl).
Solvating dichloromethane in the structure of 2a ‚CH2Cl2 is
extensively disordered and was modeled as if being contributed
from two positions (one of which adopted two orientations,
ratio 0.80:0.20) to sum up to one solvate molecule per the
complex molecule. Due to the complex nature of the dis-
order, the solvating molecules were included in the model
without the hydrogen atoms. Relevant crystallographic data
and data on structure refinement are given in Table 5. CCDC
reference numbers: CCDC-225468 (2a ‚CH2Cl2), CCDC-225469
(2b), CCDC-225470 (7), CCDC-225471 (6‚CHCl3), and CCDC-
225472 (9).
0487) and is a part of a long-term research plan of the
Faculty of Science, Charles University. The Grant
Agency of the Czech Republic also sponsored access to
the Cambridge Structural Database (Grant No. 203/02/
0436).
Su p p or tin g In for m a tion Ava ila ble: A drawing of the
molecular structure of 7 and full listings of the refined atomic
coordinates, anisotropic thermal motion parameters, calculated
hydrogen coordinates, bond distances, and bond angles for all
crystallographically characterized compounds; these data are
also available as CIF files. This material is available free of
charge via the Internet at http://pubs.acs.org.
Ack n ow led gm en t. This work was financially sup-
ported by the Grant Agency of the Czech Republic
(Grant Nos. 203/01/P002, 203/99/M037, and 203/04/
OM040007F