Synthesis, Characterization, and Reactivity of (Fluoroalkyl)- and (Fluorocycloalkyl)cobaloximes: Molecular Structure of a (2-Fluorocyclohexyl)cobaloxime Complex and Hindered Rotation of 2-Fluorocycloalkyl Ligands

Article abstract of DOI:10.1021/om030525a

The preparation of fluoroalkyl and fluorocycloalkyl was discussed. The synthesis and characterization proved that the C-F activation was restricted to fluorine substitution at the β position. Molecular structures of the compound was found to exhibit complexes with an equitorial pseudomacrocyclic ligands as well as axial base and organo ligand in mutually trans positions.

Full text of DOI:10.1021/om030525a

Organometallics 2003, 22, 4873-4884
4873
Syn th esis, Ch a r a cter iza tion , a n d Rea ctivity of
(F lu or oa lk yl)- a n d (F lu or ocycloa lk yl)coba loxim es:
Molecu la r Str u ctu r e of a (2-F lu or ocycloh exyl)coba loxim e
Com p lex a n d Hin d er ed Rota tion of 2-F lu or ocycloa lk yl
Liga n d s
J elena Galinkina,† Eduard Rusanov,† Christoph Wagner,† Harry Schmidt,†
Dieter Stro¨hl,‡ Sven Tobisch,† and Dirk Steinborn*,†
Institut fu¨r Anorganische Chemie und Institut fu¨r Organische Chemie,
Martin-Luther-Universita¨t Halle-Wittenberg, Kurt-Mothes-Strasse 2, D-06120 Halle, Germany
Received J uly 8, 2003
Reaction of Ph3P-[Co]- ([Co] ) Co(dmgH)2; dmgH2 ) dimethylglyoxime), prepared by
reduction of Ph3P-[Co]-Cl with NaBH4 in methanolic NaOH, with BrCH2CH2CH2F resulted
in formation of Ph3P-[Co]-CH2CH2CH2F (3). In neutral methanolic solutions py*-[Co]-
H/py*-[Co]- (py* ) py, 4-(t-Bu)py, 3-Fpy; 4-(t-Bu)py ) 4-tert-butylpyridine, 3-Fpy )
3-fluoropyridine) were found to react with BrCH2CHF2, yielding the 2,2-difluoroethyl
complexes py*-[Co]-CH2CHF2 (py* ) py (4a ), 4-(t-Bu)py (4b), 3-Fpy (4c)). Reactions of
XCH2CH2F (X ) Br, TfO; TfO ) triflate) with reduced cobaloximes in alkaline and neutral
methanolic solutions resulted in formation of the 2-methoxyethyl complexes py*-[Co]-CH2-
CH2OMe (py* ) py (5a ), 4-(t-Bu)py (5b), 3-Fpy (5c)) with ethylene as side product. py*-
[Co]-H/py*-[Co]- (py* ) py, 3-Fpy) was found to react with TfOCH2CMe2F, yielding py*-
[Co]-CHdCMe2 (py* ) py (6a ), 3-Fpy (6b)) and H2CdCMe2. All these reactions indicate
the formation of the (unseen) intermediate py*-[Co]-CH2CR2F (R ) H, Me), which
decomposes via nucleophilic substitution (F f OMe), heterolytic fragmentation, yielding
olefins, and HF elimination, yielding vinyl complexes, respectively. Analogous reactions of
reduced cobaloximes with trans-1-bromo-2-fluorocyclohexane and trans-1-bromo-2-fluoro-
cyclopentane resulted in the formation of (2-fluorocyclohexyl)- and (2-fluorocyclopentyl)-
cobaloximes, py*-[Co]-C6H10F (py* ) py (7a ), 4-(t-Bu)py (7b)) and py*-[Co]-C5H8F (py*
1
) py (10a ), 4-(t-Bu)py (10b)). All these complexes were fully characterized by H, 13C, and
19F NMR spectroscopic investigations. Molecular structures of the cobaloximes 3, 4a , 7b,
and 7b‚CH2Cl2 were obtained by single-crystal X-ray diffraction analyses, exhibiting
complexes with an equatorial pseudomacrocyclic (dmgH)2 ligand as well as axial base (PPh3,
py*) and organo ligand in mutually trans positions. The cycloalkyl complexes are the ae
isomers, having the sterically demanding Co(dmgH)2 moieties as equatorial substituents.
The axially oriented fluoro substituents give rise to hindered rotation of 2-fluorocycloalkyl
1
ligands, as indicated by two distinct sets of signals for dmgH ligands in the H and 13C
NMR spectra. Further proof for this came from DFT calculations of py-[Co]-C6H10F (11)
and, for comparison, of the cyclohexyl complex py-[Co]-C6H11 (12). The conformational
energy diagrams of 11 and 12 are discussed.
1. In tr od u ction
containing alkyl or cycloalkyl ligands having carbon
atoms with fluorine and hydrogen atoms (-CH2F,
-CHF2, -C(R)HF; R ) alkyl) have been much less
investigated. Thus, up to now transition-metal com-
The strongest carbon-element single bond is the C-F
bond. This, along with the small size and high elec-
tronegativity of fluorine atoms, is the reason for numer-
ous unusual and sometimes unique stabilities and
reactivities of organometallics containing fluorinated
ligands. Thus, C-F bond activation is a challenge in
organometallic and coordination chemistry.1 The chem-
istry of organometallics with perfluorinated hydrocarbon
ligands has been well explored ever since the synthesis
of [Mn(CF3)(CO)5] in 1959, the first transition-metal
complex of this type.2 On the other hand, complexes
(1) Recent review articles: (a) Harrison, R. G.; Richmond, T. G.
Chemtracts: Inorg. Chem. 1993, 5, 115-118. (b) Richmond, T. G.
Chemtracts: Inorg. Chem. 1994, 6, 39-44. (c) Kiplinger, J . L.;
Richmond, T. G.; Osterberg, C. E. Chem. Rev. 1994, 94, 373-431. (d)
Osterberg, C. E.; Richmond, T. G. Inorganic Fluorine Chemistry; ACS
Symposium Series No. 555; American Chemical Society: Washington,
DC, 1994; pp 392-404. (e) Burdeniuc, J .; J edlicka, B.; Crabtree, R. H.
Chem. Ber./ Recl. 1997, 130, 145-154. (f) Krogh-J espersen, K.; Gold-
man, A. S. Transition State Modeling for Catalysis; ACS Symposium
Series 721; American Chemical Society: Washington, DC, 1999; pp
151-162. (g) Richmond, T. G. Top. Organomet. Chem. 1999, 3, 243-
269. (h) Richmond, T. G. Angew. Chem. 2000, 112, 3378-3380.
(2) Review: Morrison, J . A. Adv. Organomet. Chem. 1993, 35, 211-
239.
† Institut fu¨r Anorganische Chemie.
‡ Institut fu¨r Organische Chemie.
10.1021/om030525a CCC: $25.00 © 2003 American Chemical Society
Publication on Web 10/23/2003

4874 Organometallics, Vol. 22, No. 24, 2003
Galinkina et al.
Sch em e 1
plexes of the type LxM-CH2CH2F have not been de-
scribed. Only in the reaction of [Rh(Cp)(η2-H2CdCH2)-
(η2-H2CdCHF)] with HCl at -80 °C, have 1H NMR
spectroscopic investigations given some indication that
[Rh(CH2CH2F)Cl(Cp)(η2-H2CdCH2)] could be formed.3
Organocobalt and, in a broader sense, also organo-
rhodium complexes with the pseudomacrocyclic bis-
(dimethylglyoximato) ligand L-[M]-R (L ) axial base,
R ) organo ligand, [M] ) M(dmgH)2, M ) Co, Rh,
dmgH2 ) dimethylglyoxime) are not only useful and
widely used vitamin B12 coenzyme models4 but proved
to be also a suitable class of organometallics that are
readily accessible with a large variety of organo ligands
R, among them heteroatom-functionalized ones. In the
case of alkyl and cycloalkyl cobaloximes and rhodoximes
with fluorine substitution5 at the â-carbon atom, the
2,2,2-trifluoroethyl complexes L-[M]-CH2CF3 (M ) Co,
2. Resu lts a n d Discu ssion
2.1. (3-F lu or op r op yl)coba loxim es. (a ) Syn th esis
a n d Ch a r a cter iza tion . Reaction of Ph3P-[Co]-, pre-
pared by reduction of Ph3P-[Co]-Cl with NaBH4 in
methanolic NaOH, with BrCH2CH2CH2F resulted in
formation of Ph3P-[Co]-CH2CH2CH2F (3) (Scheme 1).
Complex 3 was isolated as orange microcrystals in 65%
yield. The identity of 3 was confirmed by microanalysis,
NMR (1H, 13C, 19F, 31P) spectroscopy, and X-ray diffrac-
tion analysis. The protons of the trimethylene group
represents an AA′MM′XX′spin system that is coupled
with the 31P nucleus (I ) 1/2, 100% natural abundance)
and the 19F nucleus (I ) 1/2, 100% natural abundance).
The protons of the 3-CH2F group appear as a doublet
of triplets (“dt”). A first-order treatment (i.e., to treat
the protons as an A2M2X2 spin system) results in
7
Rh)6 and 2,2-difluoroethyl complexes L-[Co]-CF2CHF2
(prepared via insertion of perfluoroethylene into the
Co-H bond) have been prepared. Our own investiga-
tions8 to obtain a monofluoroethyl rhodoxime complex
in the reaction of Ph3P-[Rh]- with BrCH2CH2F resulted
in a C-F activation reaction to generate the binuclear
ethylene-bridged rhodoxime complex Ph3P-[Rh]-CH2-
3
2
coupling constants J H,H ) 6.5 Hz and J F,H ) 47.7 Hz.
2
The coupling J F,H is virtually the same as that in
1-fluoropropane (48.5 Hz).11 As for other organoco-
baloximes, the large electric quadrupole moment of
59Co (0.42 × 10-28 m2)12 combined with I ) 7/2 gave rise
to line broadening so that the signal of the 13C nucleus
directly bound to cobalt could not be detected. δC(CH2F)
9
CH2-[Rh]-PPh3 in high yields. This unexpected reac-
tion prompted us to extend our investigations on
cobaloximes and on analogous reactions using 2,2-
difluoroethyl (BrCH2CHF2) as well as monofluoro-
substituted compounds with better leaving groups and/
or higher carbon substitution (TfOCH2CH2F; TfOCH2-
CMe2F; 1-bromo-2-fluorocyclohexane and -pentane).
Thus, we succeeded in synthesizing and fully character-
izing Ph3P-[Co]-CH2CHF2, py*-[Co]-C6H10F, and
py*-[Co]-C5H8F (py* ) py, 4-(t-Bu)py; C6H10F )
2-fluorocyclohexyl; C5H8F ) 2-fluorocyclopentyl). For the
first time, 2,2-difluoroethyl and 2-fluorocyclohexyl tran-
sition-metal complexes could also be characterized
structurally. NMR spectroscopic investigations gave
evidence for hindered rotation of 2-fluorocycloalkyl
ligands around the Co-C bond. To get further proof that
the C-F activation described above is restricted to
fluorine substitution at the â-position, we synthesized
and characterized the 3-fluoropropyl complex Ph3P-
[Co]-CH2CH2CH2F as well. Part of this work has been
previously reported.10
1
and J F,C in complex 3 are close to the corresponding
values in 1-fluoropropane13 (83.3 vs 85.2 ppm, 167.3 vs
163.3 Hz).
(b) Molecu la r Str u ctu r e. The molecular structure
of complex 3, obtained by single-crystal X-ray diffraction
analysis, is shown in Figure 1. Selected bond lengths
and angles are given in Table 1. Co is coordinated in a
distorted-octahedral geometry by four nitrogen atoms
of the pseudomacrocyclic (dmgH)2 ligand in the equato-
rial plane and by one carbon and one phosphorus atom
of the 3-fluoropropyl and triphenylphosphine ligands,
respectively, in mutually trans positions (C9-Co-P )
173.9(1)°). Distortion of the Co(dmgH)2 moiety is rela-
tively small, as the distance d of the cobalt atom from
the mean N4 plane and the dihedral angle R between
the two dmgH planes exhibit (d ) +0.066(1) Å, R ) 1.7-
(2)°; positive values indicate displacement toward L and
bending toward R).14 The 3-fluoropropyl ligand exhibits
a fully staggered conformation (Co-C9-C10-C11 )
175.4(3)°). The C-F bond in 3 has the same length as
that in the corresponding rhodoxime Ph3P-[Rh]-CH2-
CH2CH2F (1.357(5) vs 1.361(8) Å8), the only further
structurally characterized 3-fluoropropyl complex. These
two C-F bonds are relatively short, as comparison with
(3) Seiwell, L. P. Inorg. Chem. 1976, 15, 2560-2563.
(4) (a) Schrauzer, G. N. Angew. Chem. 1976, 88, 465-474. (b)
Schrauzer, G. N. Angew. Chem. 1977, 89, 239-251. (c) Randaccio, L.
Comments Inorg. Chem. 1999, 21, 327-376.
(5) Review on cobaloximes with fluorinated alkyl ligands: Toscano,
P. J .; Barren, E.; Brand, H.; Konieczny, L.; Schermerhorn, E. J .;
Shufon, K.; van Winkler, S. Inorganic Fluorine Chemistry; ACS
Symposium Series 555; American Chemical Society: Washington, DC,
1994; pp 286-296.
(6) (a) Randaccio, L.; Bresciani-Pahor, N.; Orbell, J . D.; Calligaris,
M.; Summers, M. F.; Snyder, B.; Toscano, P. J .; Marzilli, L. G.
Organometallics 1985, 4, 469-478. (b) Bresciani-Pahor, N.; Calligaris,
M.; Randaccio, L.; Marzilli, L. G.; Summers, M. F.; Toscano, P. J .;
Grossman, J .; Liotta, D. Organometallics 1985, 4, 630-636. (c) Dreos
Garlatti, R.; Tauzher, G.; Costa, G. Inorg. Chim. Acta 1986, 121, 27-
32. (d) Randaccio, L.; Geremia, S.; Dreos-Garlatti, R.; Tauzher, G.;
Asaro, F.; Pellizer, G. Inorg. Chim. Acta 1992, 194, 1-8.
(7) (a) Geremia, S.; Randaccio, L.; Zangrando, E. Gazz. Chim. Ital.
1992, 122, 229-232. (b) Randaccio, L.; Geremia, S.; Zangrando, E.;
Ebert, C. Inorg. Chem. 1994, 33, 4641-4650.
(10) Galinkina, J .; Wagner, C.; Rusanov, E.; Schmidt, H.; Steinborn,
D. Challenges for Coordination Chemistry in the New Century; Monogr.
Ser. Int. Conf. Coord. Chem. 5; Slovak Technical University Press:
Bratislava, 2001; pp 177-182.
(11) Weigert, F. J . J . Org. Chem. 1980, 45, 3476-3483.
(12) Mason, J ., Ed. Multinuclear NMR; Plenum: New York, 1987;
p 626.
(13) (a) Wiberg, K. B.; Pratt, W. E.; Bailey, W. F. J . Org. Chem.
1980, 45, 4936-4947. (b) Kalinowski, H.-O.; Berger, S.; Braun, S. 13C
NMR-Spektroskopie; Thieme: Stuttgart, Germany, 1984; p 522.
(14) (a) Bresciani-Pahor, N.; Forcolin, M.; Marzilli, L. G.; Randaccio,
L.; Summers, M. F.; Toscano, P. J . Coord. Chem. Rev. 1985, 63, 1-125.
(b) Randaccio, L.; Bresciani-Pahor, N.; Zangrando, E. Chem. Soc. Rev.
1989, 18, 225-250.
(8) Rausch, M.; Bruhn, C.; Steinborn, D. J . Organomet. Chem. 2001,
622, 172-179.
(9) Steinborn, D.; Rausch, M.; Bruhn, C.; Schmidt, H.; Stro¨hl, D. J .
Chem. Soc., Dalton Trans. 1998, 221-230.

(Fluoroalkyl)- and (Fluorocycloalkyl)cobaloximes
Organometallics, Vol. 22, No. 24, 2003 4875
Sch em e 2
(A, M ) 1H, X ) 19F), the proton resonances have a first-
order appearance (see Figure 2, for example). The 1-CH2
groups appear as pseudotriplets of doublets and the
2-CHF2 groups as pseudotriplets of triplets. Fluorine-
hydrogen couplings were obtained in first-order treat-
ments of the spectra. They are very similar to those in
2
1,1-difluoroethane:16 J F,H ) 58.7-58.9 Hz vs 56.7 Hz
3
and J F,H ) 21.7-22.1 Hz vs 19.9 Hz. Splitting of the
signals of the 2-C atoms into triplets (1J F,C ) 240.5-
1
240.9 Hz; for comparison CH3CHF2 with J F,C ) 233.5
Hz) is indicative of CHF2 groups. In comparison with
1,1-difluoroethane, the 19F resonances in complexes
4a -c are low-field shifted by about 7-8 ppm (-101.4
to -101.8 ppm vs -109.3 ppm16).
F igu r e 1. Molecular structure of Ph3P-[Co]-CH2CH2-
CH2F (3) showing the numbering scheme (displacement
ellipsoids at 30% probability).
(b) Molecu la r Str u ctu r e. Crystals of py-[Co]-CH2-
CHF2 (4a ) suitable for X-ray diffraction measurements
were obtained from thf/diethyl ether. Crystals contain
discrete molecules of 4a without unusual intermolecular
interactions. The molecular structure is shown in Figure
3. The difluoroethyl ligand is disordered over three
positions with occupancies of 40 (A), 35 (B), and 25%
(C) (see the Experimental Section). As shown in Figure
3, this is due to a “rotation” of the CHF2 group around
the Co-C9 and C9-C10 bonds. Disorder of this type
may be caused by the well-known ability of fluorine to
substitute hydrogen in organics without causing gross
geometrical distortions (cf. typical bond lengths 1.3 Å
for C-F with 1.0 Å for C-H and van der Waals radii of
1.20-1.45 Å for H and 1.50-1.60 Å for F).17 Pyridine
and difluoroethyl ligands are in mutually trans position
(N5-Co-C9A ) 170.8(4)°). The Co-C bonds in co-
baloximes py*-[Co]-R with fluorinated ethyl ligands
(Table 2) are all of the same length (1.997(6)-2.03(2)
Å) within the 3σ criterion. In organocobaloximes py-
[Co]-R the length of the Co-Npy bond can be considered
to be a measure for the (structural) trans influence of
organo ligand R. Values of complexes with fluorinated
ethyl ligands are shown in Table 2.18 Although com-
plexes having differently substituted pyridine bases and
differently distorted coordination polyhedra (measured
by d and R; see Table 2) are compared, it can be seen
that all fluorine-substituted ethyl ligands exhibit a
smaller (structurally) trans influence than the ethyl
ligand, whereas differences within the fluorine-substi-
Ta ble 1. Selected In ter a tom ic Dista n ces (in Å) a n d
An gles (in d eg) for P h 3P -[Co]-CH2CH2CH2F (3)
Co-P
Co-C9
C9-C10
2.4121(8)
2.050(3)
1.479(5)
C10-C11
C11-F
Co-NdmgH
1.517(5)
1.357(5)
1.877(3)-1.880(3)
P-Co-C9
173.9(1)
Co-C9-C10
120.8(3)
111.2(4)
110.3(4)
170.1(4)
N1-Co-N4
174.9(1)
177.1(1)
175.4(3)
C9-C10-C11
C10-C11-F
N2-Co-N3
Co-C9-C10-C11
C9-C10-C11-F
C-F bonds in organic -CH2F and >CHF compounds
reveals (median, 1.399 Å; lower/upper quartile, 1.389/
1.408 Å; 25 observations).15
2.2. (2,2-Diflu or oeth yl)coba loxim es. (a ) Syn th e-
sis a n d Ch a r a ct er iza t ion . Reduced cobaloximes
L-[Co]- with phosphines (L ) PBu3, PPh3) as axial
bases were found to react with BrCH2CHF2, yielding
only vinyl fluoride. The formation of 2,2-difluoroethyl
complexes could not be established. In contrast to this,
the reaction of py-[Co]-, prepared by reduction of py-
[Co]-Cl with NaBH4 in methanolic NaOH, resulted in
the formation of the expected 2,2-difluoroethyl complex
py-[Co]-CH2CHF2 (4) in 26% yield. Vinyl fluoride was
found to be a side product. Higher yields were obtained
in neutral solutions. Thus, reactions of py*-[Co]-Cl
(py* ) py, 4-(t-Bu)py, 3-Fpy) with NaBH4 in methanol
at -30 °C gave a mixture of py*-[Co]- and py*-[Co]-
H (pKa ≈ 10)4a that reacts with BrCH2CHF2, giving the
2,2-difluoroethyl complexes py*-[Co]-CH2CHF2 (4a -
c) in 38-57% yields (Scheme 2). Vinyl fluoride was also
found to be a side product.
(16) (a) Foris, A. Magn. Reson. Chem. 2001, 39, 386-398. (b) Kraft,
B. M.; Lachicotte, R. J .; J ones, W. D. J . Am. Chem. Soc. 2001, 123,
10973-10979.
The identities of (2,2-difluoroethyl)cobaloximes 4a -c
1
were confirmed by microanalyses and H, 13C, and 19F
(17) (a) Huheey, J . A.; Keiter, E. A.; Keiter, R. L. Inorganic
Chemistry: Principles of Structure and Reactivity, 4th ed.; Harper
Collins: New York, 1993; p 292. (b) Smart, B. E. In Chemistry of
Organic Fluorine Compounds II; Hudlicky, M., Pavlath, A. E., Eds.;
ACS Monograph 187; American Chemical Society: Washington, DC,
1995; pp 979-1010.
NMR spectroscopic investigations as well as for 4a also
by X-ray crystallography. Although the protons of the
CH2CHF2 ligand are part of an AA′MXX′ spin system
(15) Allen, F. H.; Kennard, O.; Watson, D. G.; Brammer, L.; Orpen,
A. G.; Taylor, R. J . Chem. Soc., Perkin Trans. 2 1987, S1-S19.
(18) Marzilli, L. G.; Summers, M. F.; Ramsden, J . H., J r.; Bresciani-
Pahor, N.; Randaccio, L. J . Chem. Soc., Dalton Trans. 1984, 511-514.

4876 Organometallics, Vol. 22, No. 24, 2003
Galinkina et al.
1
F igu r e 2. 200 MHz H NMR spectrum of py-[Co]-CH2CHF2 (4a ).
Ta ble 2. Str u ctu r a l P a r a m eter s for Or ga n ocoba loxim es p y*-[Co]-R w ith F lu or in a ted Eth yl Liga n d s R
(Va lu es for R ) Et for Com p a r ison )
Co-Npy
(Å)
Co-C
(Å)
da
(Å)
Ra
(deg)
py*
ref
CH2CH3
CH2CF3
CF2CHF2
CH2CHF2
CF2CF3
4-[HNdC(OMe)]py
4-(NC)py
py
py
py
2.081(3)
2.041(2)
2.036(4)
2.030(4)
2.024(6)
2.035(5)
2.010(3)
1.997(6)
2.03(2)
0.05
0.01
-0.03
0.004(1)
9.1
1.0
-9.5
1.9(4)
-8.8
18
6b
7a
b
2.013(3)
-0.04
5
a
Displacement d of the Co atom out of the mean N4-plane and interplanar angle R between the two dmgH ligands. Positive values
b
indicate displacement toward py* and corresponding bending away from py*. This work.
tuted ligands are only small. So far, complex 4a is the
only structurally characterized transition-metal complex
having a 2,2-difluoroethyl ligand.
plexes 5a -c, but in lower yields (9-24%). Analogous
results were obtained in the reaction between py-[Co]-
and TfOCH2CH2F. Furthermore, a stabilization of the
expected intermediate 2-fluoroethyl complex could not
be achieved when the two â-hydrogen atoms were
replaced by more bulky methyl groups: as shown in
Scheme 3, reactions of TfOCH2CMe2F with py*-[Co]-
H/py*-[Co]- (py* ) py, 3-Fpy) resulted in formation of
complexes 6a ,b in low yields (15 and 5%, respectively).
Isobutylene was found as a side product. From proposed
(unseen) intermediates (py*-[Co]-CH2CMe2F), 2-me-
thylprop-1-enyl complexes 6a ,b could be formed by HF
elimination and isobutylene by heterolytic fragmenta-
tion.
2.3. (2-F lu or oa lk yl)- a n d (2-cycloa lk yl)cob a l-
oxim es. (a ) Syn th esis a n d Rea ctivity. Reactions of
py*-[Co]-, prepared by reduction of py*-[Co]-Cl with
NaBH4 in methanolic NaOH, with BrCH2CH2F resulted
in formation of the (2-methoxyethyl)cobaloximes 5a -c
in (isolated) yields between 20 and 37% (Scheme 3).
Ethylene was identified as a side product. Formation
of these two products can be explained when the
(unseen) 2-fluoroethyl complexes py*-[Co]-CH2CH2F
are assumed as intermediates: nucleophilic substitution
of fluorine by a methoxy group gave rise to formation
of complexes 5 and heterolytic fragmentation19 to for-
mation of ethylene (Scheme 3). Even in neutral solutions
at -30 °C, py*-[Co]-H/py*-[Co]- reacted with BrCH2-
CH2F, giving ethylene and the 2-methoxyethyl com-
The identities of (2-methoxyethyl)cobaloximes 5a -c
and of (2-methylprop-1-enyl)cobaloximes 6a ,b were
confirmed unambiguously by 1H and 13C NMR mea-
surements (see the Experimental Section). In complexes
5a -c the protons of the Co-CH2CH2OMe groups give
(19) (a) Grob, C. A.; Schiess, P. W. Angew. Chem. 1967, 79, 1-14.
(b) Grob, C. A. Angew. Chem. 1969, 81, 543-554.
1
AA′XX′ (A, X ) H) spin systems. Due to nonresolved

(Fluoroalkyl)- and (Fluorocycloalkyl)cobaloximes
Organometallics, Vol. 22, No. 24, 2003 4877
4-(t-Bu)py) with trans-1-bromo-2-fluorocyclohexane af-
forded the (2-fluorocyclohexyl)cobaloximes 7a ,b in 35
and 40% yields, respectively (Scheme 4). Cyclohexene
was identified as a side product. For comparison, the
analogous reaction of py-[Co]-H/py-[Co]- with bro-
mocyclohexane was performed, giving the cyclohexyl-
cobaloxime complex py-[Co]-C6H11 (8) in 42% yield.
Qualitatively, no difference in reactivity between bro-
mocyclohexane and trans-1-bromo-2-fluorocyclohexane
was observed.
The reaction of py-[Co]-H/py-[Co]- with the analo-
gous cis derivative cis-1-bromo-2-fluorocyclohexane re-
sulted also in formation of the 2-fluorocyclohexyl com-
plex 7a , but in much lower yield (<5%). Careful
examination of the purity of the starting material made
it clear that impurities of trans-1-bromo-2-fluorocyclo-
hexane in the starting material (cis-1-bromo-2-fluoro-
cyclohexane) as a source for complex 7a can be excluded.
In alkaline solutions, py-[Co]- was found to react with
cis-1-bromo-2-fluorocyclohexane, forming complex 7a in
very low yield (about 3%). Longer reaction times gave
rise to formation of a mixture of the desired 2-fluoro-
cyclohexyl complex 7a and the (cyclohex-1-enyl)co-
baloxime py-[Co]-C6H9 (9; C6H9 ) cyclohex-1-enyl) in
about a 1:1 ratio (total yield ca. 3%). In close analogy to
trans-1-bromo-2-fluorocyclohexane, trans-1-bromo-2-
fluorocyclopentane was found to react with py*-[Co]-
H/py*-[Co]- (py* ) py, 4-(t-Bu)py) within 8 h, giving
(2-fluorocyclopentyl)cobaloximes 10a ,b in 45 and 47%
yields (Scheme 5).
F igu r e 3. Molecular structure of py-[Co]-CH2CHF2 (4a ,
molecule A) (displacement ellipsoids at 30% probability)
(top) and disorder of the 2,2-difluoroethyl ligand (bottom).
Selected bond lengths (Å) and angles (deg): Co-N5 )
2.030(4), Co-C9A ) 2.03(2), C9A-C10A ) 1.495(8), C10A-
F1A ) 1.342(8), C10A-F2A ) 1.345(8), Co-NdmgH ) 1.885-
(4)-1.896(4); N5-Co-C9A ) 170.8(4), Co-C9A-C10A )
118(1), C9A-C10A-F1A ) 108(1), C9A-C10A-F2A )
110(1), N1-Co-N4 ) 179.7(2), N2-Co-N3 ) 179.4(2)°.
Values for molecules B and C are given in the Supporting
Information.
The (2-fluorocyclohexyl)- (7a ,b) and (2-fluorocyclo-
pentyl)cobaloximes (10a ,b) were isolated as brown (7a ,
10a ) and orange (7b, 10b) microcrystals that are stable
for several days in air. They decompose at 160/150 °C
(7a /b) and 155/150 °C (10a /b) without melting. Ther-
mogravimetric investigations of 7b and 10b showed that
decomposition takes place between 150 and 400 °C in
three steps that are not well separated from each other
(total mass loss about 75%). The identities of complexes
1
7a ,b and 10a ,b were proved by microanalysis and H,
13C, and 19F NMR spectroscopy as well as for complex
ab subsystems,20 the four protons appear as pairs of
approximately 1:1:1 triplets with broadened middle lines
(N ) J A,X + J A,X′ ) 16.0-16.6 Hz).
On the other hand, reactions of reduced cobaloximes
with 1-bromo-2-fluorocycloalkanes proceeded with for-
mation of the expected (2-fluorocycloalkyl)cobaloximes.
Thus, reactions of py*-[Co]-H/py*-[Co]- (py* ) py,
7b by single-crystal X-ray crystallography as well.
(b) Molecu la r Str u ctu r e of 4-(t-Bu )p y-[Co]-
C6H10F (7b). Slow evaporation of solvent at room
temperature from solutions of complex 7b in methylene
chloride/n-hexane resulted in crystallization of brown
crystals of the composition [Co(C6H10F)(dmgH)2{4-(t-
Sch em e 3

4878 Organometallics, Vol. 22, No. 24, 2003
Galinkina et al.
Sch em e 4
Sch em e 5
Bu)py}]‚CH2Cl2 (7b‚CH2Cl2). Evaporation of solvent to
dryness gave rise to formation of single crystals of the
composition [Co(C6H10F)(dmgH)2{4-(t-Bu)py}] (7b). Both
crystal structures consist of discrete molecules of [Co-
(C6H10F)(dmgH)2{4-(t-Bu)py}] (and methylene chloride
in 7b‚CH2Cl2) without unusual intermolecular interac-
tions (shortest intermolecular contacts between non-
hydrogen atoms >3.3 Å). The molecular structures along
with the numbering schemes are shown in Figure 4.
Selected bond lengths, bond angles, and torsion angles
are given in Table 3. In both cases the space groups are
nonchiral (Pna21, 7b; Cc, 7b‚CH2Cl2) and the unit cells
contain four formula units. The molecule of 7b has two
chiral centers with opposite configuration: C9R/C10S
and vice versa C9S/C10R. Thus, in both of these crystals
each unit cell contains two pairs of enantiomers. In 7b‚
CH2Cl2 the fluoro substituent is disordered over two
positions with occupancies of 68% (-C10HF-) and 32%
(-C14HF-). Both positions are equivalent, and the
disorder may be due to similar van der Waals radii of
H and F (1.20-1.45 vs 1.50-1.60 Å17). Two superim-
posed molecules have opposite configurations (C9R/C10S
(68%) T C9S/C14R (32%) and vice versa). Thus, the unit
cell also contains the enantiomers pairwise. As shown
in Table 3, both molecules exhibit a very similar
structure. Due to the disorder described above, in the
following all values given refer to molecules in crystals
of 7b.
The geometry around the central Co atom is distorted
octahedral with four N-atom donors of the pseudomac-
rocyclic (dmgH)2 ligand in equatorial positions. 4-tert-
Butylpyridine and the 2-fluorocyclohexyl ligand are
axially coordinated (C9-Co-N5 ) 176.9(1)°). The cy-
clohexyl ring exhibits a chair conformation in a very
good approximation:21 the C-C-C-C torsion angles of
the six-membered cycle are between 52.8(5) and 56.0-
(4)° with alternate signs. The 1,2-disubstituted cyclo-
F igu r e 4. Molecular structure of 4-(t-Bu)py-[Co]-C6H10
F
(C6H10F ) 2-fluorocyclohexyl) in crystals of 7b (top) and
7b‚CH2Cl2 (bottom, without H atoms bound to carbon)
showing the numbering scheme (FA/FB major/minor oc-
cupied position, 68/32%; displacement ellipsoids at 30%
probability).
hexane adopts the (cis) ae conformation. As expected,
the bulky Co(dmgH)2 moiety occupies an equatorial
position and the much smaller fluoro substituent an
axial position. The C-F bond (1.428(5) Å) is long
(20) Gu¨nther, H. Angew. Chem. 1972, 84, 907-920.
(21) Bucourt, R. Top. Stereochem. 1974, 8, 159-224.

(Fluoroalkyl)- and (Fluorocycloalkyl)cobaloximes
Organometallics, Vol. 22, No. 24, 2003 4879
Ta ble 3. Selected Bon d Len gth s (in Å) a n d An gles
(in d eg) for 4-(t-Bu )p y-[Co]-C6H10F in Cr ysta ls of
7b a n d 7b‚CH2Cl2 a n d Ca lcu la ted Va lu es for
p y-[Co]-C6H10F (11a )
should appear as singlet resonances (averaged chemical
shifts result in coalescence to one resonance signal on
the NMR time scale). Frozen rotation, the other bor-
derline case, reduces the symmetry to C1, and four
distinct signals should be found. Due to the symmetry
of (dmgH)2 ligand, hindered rotation results in pairwise
symmetrically equivalent positions that are interrelated
by C2 symmetry. One preferred orientation (having two
equivalent positions) gives rise to two distinct signals
with 1:1 intensities. This case was found experimentally
(see Table 4). Temperature-dependent 1H NMR spec-
troscopic measurements for 7b support this interpreta-
tion: the shift difference ∆δ between the two methyl
proton resonances decreases from 31.9 Hz at -80 °C to
6.5 Hz at +99 °C (for details, see the Experimental
Section). The solvent properties did not allow us to
extend the temperature range. Thus, the two expected
borderline situations (four distinct resonances vs one
averaged resonance) could not be detected experimen-
tally. Furthermore, NOE experiments (DPFGSE-NOE:
double pulsed field gradient spin-echo NOE) of complex
7b support this argument: saturating the very well
shift-separated -CHF resonance (δ 4.70) of the 2-fluo-
rocyclohexyl ligand of 7b resulted in enhancement of
intensity of one of the two methyl signals (intensity ratio
δ(CH3)1065 Hz/δ(CH3)1058 Hz in the NOE spectrum ca. 1/3).
A similar phenomenon has been already observed: thus,
hindered rotation of the axial 2-aminopyridine ligand
in 2-(H2N)py-[Co]-CH2CF3, caused by H-bonding of the
NH2 group to O-H‚‚‚O bridges of the dimethylglyoxi-
mato ligands, resulted in splitting of glyoximato CH3
group signals into two separate resonances.25
7b
7b‚CH2Cl2
11a a
Co-N5
2.085(3)
2.082(3)
1.428(5)
2.086(3)
2.066(4)
1.434(6)b
2.142
2.046
1.422
Co-C9
C14-F
C-Cc-hex
Co-NdmgH
1.501(7)-1.532(5) 1.495(8)-1.547(6) 1.526-1.545
1.885(3)-1.890(2) 1.884(4)-1.898(3) 1.908-1.931
N5-Co-C9 176.9(1)
N1-Co-N4 179.2(1)
N2-Co-N3 179.1(1)
C9-C14-F 109.7(3)
Co-C9-C14 116.1(2)
176.5(2)
179.1(2)
179.2(2)
176.47
178.42
178.48
110.03
116.21
53.2-57.7
109.6(4)c
115.9(3)d
51.3(7)-55.7(5)
C-C-C-
Cc-hex
52.8(5)-56.0(4)
e
a
Fully optimized structure at the DFT level of theory (B3LYP/
BS2). C14-FA. C10-FB ) 1.49(2) Å. c C9-C14-FA. C9-C10-
b
FB ) 101.9(7)°. Co-C9-C10 ) 116.2(3)°. e Absolute values are
d
given.
compared with C-F bonds in 1,2-disubstituted fluoro-
cyclohexanes (median, 1.394 Å, lower/upper quartile,
1.383/1.404 Å; n ) 5).22 The Co-C9 bond in 7b is as
long as that in the cyclohexylcobaloxime complex Me3-
bzm-[Co]-C6H11 (Me3bzm ) 1,5,6-trimethylbenzimi-
dazole):23 2.082(3) vs 2.073(4) Å.
(c) NMR Sp ectr oscop ic In vestiga tion s. Selected
1H, 13C, and 19F NMR parameters of (2-fluorocycloalkyl)-
cobaloximes are given in Table 4. All these data clearly
indicate the constitution of the complexes. Protons of
CHF groups appear at lower field (δ 4.70-4.83), and
thus they are well separated from other cycloalkyl
protons. The large quadrupole moment of the 59Co
7
(d ) Qu a n tu m Ch em ica l Ca lcu la tion s. To get fur-
ther insight into hindered rotation, quantum chemical
calculations on the DFT level of theory were performed.
As a model complex, we chose py-[Co]-C6H10F (11),
which is identical with complex 7a . Calculations were
performed in the gas phase, and solvation effects were
not considered. The calculated structure of the most
stable conformer 11a (Figure 5) proved to be very
similar to the molecular structure of 4-(t-Bu)py-[Co]-
C6H10F (7b) in the solid state, as comparison to Table 3
reveals. Especially, the orientation of the axial 2-fluo-
rocyclohexyl ligand with respect to the equatorial
(dmgH)2 ligand measured by means of the torsion angle
N1-Co-C9-C14 (16.5°) is close to that found in 7b
(2.6°) and 7b‚CH2Cl2 (25.6° for the major occupied
position and N2-Co-C9-C14 ) -26.8° for the minor
occupied position). In all these structures the fluoro
substituent lies approximately above a CdN carbon
atom (Figure 6). As the conformational energy diagram
nucleus combined with I ) /2 gave rise to broadening
the C1 carbon resonances. Therefore, good signal-to-
noise ratios were necessary to detect them. The reso-
nances of carbon atoms C1 (δ 46.4, 7b; δ 41.9, 10a ), C2
(δ 96.4-101.5), and fluorine atoms (δ -177.1 to -189.2)
are low-field shifted compared with those in fluorocy-
clohexane and -pentane (C6H11F/C5H9F: δCH CHF 32.2/
2
33.4; δCHF 91.0/96.5; δF -170.5/-174.2).13a,24
1
The most striking features in the H and 13C spectra
are the two sets of all signals of the dimethylglyoximato
ligands (except for the methyl carbon resonances in
10a ,b), showing that there is a hindered rotation of
2-fluorocycloalkyl ligands around the Co-C bonds: the
2-fluorocycloalkyl ligands in py*-[Co]-C6H10F (7a ,b)
and py*-[Co]-C5H8F (10a ,b) contain a chiral carbon
atom. Free rotation around the Co-C bond gives rise
to chemical equivalence of all four methyl groups of the
equatorial (dmgH)2 ligand. Thus, due to the mean C2v
symmetry, methyl groups in 1H and 13C NMR spectra
Ta ble 4. Selected NMR Sp ectr oscop ic Da ta (δ in p p m , J in Hz) of (2-F lu or ocycloh exyl)coba loxim es
p y*-[Co]-C6H10F (7a ,b) a n d (2-F lu or ocyclop en tyl)coba loxim es p y*-[Co]-C5H8F (10a ,b)
organo ligand
(dmgH)2
C2HF
δH (2J F,H
CH3
C1H
δC
C3H2
C5H2 C4H2/C6H2
δC δC
CdN
δC
δC (1J F,C
)
)
δF
δC (2J F,C
)
δC
δH
py-[Co]-C6H10F (7a ) 96.4 (171.1)
4.70 (47.5) -189.2
a
34.6 (24.1) 20.9 29.2/29.6
11.97/12.01 2.10/2.12 150.1/150.9
4-(t-Bu)py-[Co]-
C6H10F (7b)
96.4 (170.7)
4.70 (47.3) -187.7 46.4 34.6 (24.0) 20.9 29.2/29.5b 11.96/12.01 2.10/2.11 149.8/150.6
py-[Co]-C5H8F (10a ) 101.2 (173.6) 4.82 (53.4) -177.1 41.9 30.6 (24.4) 19.1 28.5
11.8
11.9
2.06/2.07 150.0/150.6
2.08/2.09 149.8/150.5
4-(t-Bu)py-[Co]-
C5H8F (10b)
101.5 (173.2) 4.83 (53.3) -177.1
a
30.7 (24.9) 19.2 28.5
a
b 3
Not found, due to line broadening.
J
) 2.9 Hz.
F,C

4880 Organometallics, Vol. 22, No. 24, 2003
Galinkina et al.
F igu r e 7. Conformational energy diagram for py-[Co]-
C6H10F (11) and py-[Co]-C6H11 (12). Equilibrium struc-
tures and transition states are marked by closed circles.
Structures 11a -d and structure 12a are shown in Figures
6 and 8, where the reference atoms for the torsion angle
N-Co-C-C are given.
F igu r e 5. Calculated structure of py-[Co]-C6H10F (11;
C6H10F ) 2-fluorocyclohexyl).
F igu r e 8. Calculated structure of the rotational conformer
of py-[Co]-C6H11 (12a , equilibrium structure, N-Co-
C-C ) 28°) (view from above, the pyridine ligand was
omitted). Reference atoms for measuring the torsion angle
N-Co-C-C (see Figure 7) are shown in gray. The mag-
nitude of torsion angles in the other equilibrium structure
12c is drawn as a solid line and in the transition states
12b and 12d as dashed lines.
F igu r e 6. Calculated structures of rotational conformers
of py-[Co]-C6H10F (11a ,c, equilibrium structures, N-Co-
C-C ) 16/117°; 11b,d , transition states, N-Co-C-C )
87/140°) (view from above, pyridine ligand was omitted).
Reference atoms for measuring the torsion angle N-Co-
C-C (see Figure 7) and the fluoro substituent are shown
in gray.
bridge and a methyl group, respectively (Figure 6). This
can be rationalized in terms of electrostatic and steric
repulsion between the fluoro substituent and the
O-H‚‚‚O and methyl groups, respectively. A conforma-
tional energy diagram for the analogous cyclohexyl-
cobaloxime complex py-[Co]-C6H11 (12) is shown in
Figure 7. The energy barrier in complex 12 (12a f 12d ,
∆E ) 3.59 kcal/mol) is roughly half of that of the fluoro-
substituted complex 11 (11a f 11b, ∆E ) 6.28 kcal/
mol; see Table 5). The absolute magnitude must not be
overestimated: energy calculations of the optimized
structures with a better basis set (see the Experimental
Section) gave smaller barriers (Table 5), but the ratio
(∆E12/∆E11) remains the same. Furthermore, consider-
ation of solvent effects may result in a shift of these
values.
(Figure 7) exhibits, rotation of 2-fluorocyclohexyl ligands
around the Co-C bond by 180° (giving a complete
picture due to the C2 symmetry of the (dmgH)2 ligand)
results in two minima and two maxima of potential
energy. In the other minimum (N1-Co-C9-C14 )
117°) the fluoro substituent also lies above one CdN
carbon atom (Figure 6). In the (global) transition state
with the highest potential energy (N1-Co-C9-C14 )
87°) and in the local transition state (N1-Co-C9-C14
) 140°), the fluoro substituent lies above the O-H‚‚‚O

(Fluoroalkyl)- and (Fluorocycloalkyl)cobaloximes
Organometallics, Vol. 22, No. 24, 2003 4881
Ta ble 5. En er gies of Equ ilibr iu m Str u ctu r es a n d
Tr a n sition Sta tes (∆E in k ca l/m ol) for
of the C-F bond in three different ways, namely (i) by
nucleophilic substitution of F- (Nu/NuH ) MeO-/
MeOH), (ii) by heterolytic fragmentation to form olefins,
and (iii) by HF elimination to yield vinyl complexes. The
last two reactions should be governed by stereoelectronic
effects. Thus, concerted heterolytic fragmentation reac-
tions and E2 elimination reactions normally require an
antiperiplanar conformation.28 Stable alkyl/cycloalkyl
complexes that are only monofluorinated at the 2-posi-
tion could only be obtained in cobaloximes with cy-
cloalkyl ligands where conformational mobility is se-
verely limited due to the space-demanding Co(dmgH)2
moiety, which can only be bound in an equatorial
position. The stability of these complexes with fluorine
in an axial position can most probably be explained by
the fact that heterolytic fragmentation is hampered by
stereoelectronic effects. Once formed, (2-fluorocycloalky-
l)cobaloximes proved to be very stable. HF elimination
yielding allyl type complexes, (cyclohex-2-enyl)-/(cyclo-
pent-2-enyl)cobaloximes, was not observed.
p y-[Co]-C6H10F (11) a n d p y-[Co]-C6H11 (12)a
N-Co-C-C
∆Eb
∆Ec
py-[Co]-C6H10F (11)
eq str (global min) (11a )
16.1
87.0
0.00
6.28
4.72
5.32
0.00
4.32
2.77
4.03
ts (global max) (11b)
eq str (local min) (11c)
ts (local max) (11d )
117.2
140.4
py-[Co]-C6H11 (12)
eq str (global min) (12a )
109.8
83.1
0.00
3.42
2.02
3.59
0.00
2.74
1.33
2.98
ts (local max) (12b)
eq str (local min) (12c)
ts (global max) (12d )
112.8
142.6
a
Conformations are characterized by the torsion angle N-Co-
C-C (in deg), See Figures 6 and 7. Basis set BS1. c Basis set BS2
(see the Experimental Section).
b
Sch em e 6
3. Exp er im en ta l Section
3.1. Gen er a l Com m en ts. All reactions with CoI were
carried out under argon using Schlenk techniques. Solvents
were dried and distilled under argon according to standard
methods. The cobaloximes L-[Co]-Cl (L ) PPh3, py, 3-Fpy,
4-(t-Bu)py) and TfOCH2CH2F and TfOCH2CMe2F were ob-
tained by published methods or in analogy to them.29-32
Reactions of cyclohexene and cyclopentene with Et3N‚3HF/N-
bromosuccinimide afforded trans-1-bromo-2-fluorocyclohexane
and -pentane.33 Ring opening of epoxycyclohexane with HF/
py (Warning! Extreme care should be exercised while handling
3.4. Con clu sion s. The steric course of reactions of
reduced cobaloximes with cyclohexyl derivatives has
been shown to proceed with inversion of configuration
at carbon, establishing the backside approach of the
cobaloxime unit toward the C-X bond.26 Furthermore,
due to the large steric requirement of the cobaloxime
group, Co(dmgH)2 is forced to take an equatorial con-
formation. Formation of cis-(2-fluorocycloalkyl)cobal-
oximes (ae isomers) 7a ,b and 10a ,b starting from trans-
1-bromo-2-fluorocycloalkanes is in accord with this. The
corresponding reaction with cis-1-bromo-2-fluorocyclo-
hexane did not proceed with formation of trans-(2-
fluorocyclohexyl)cobaloxime (ee isomer) but with forma-
tion of the cis isomers 7a in very small yield. In contrast,
analogous reactions of cis- and trans-1-bromo-2-fluoro-
cyclohexane with trans-[IrCl(CO)(PMe3)2] proceeded
with loss of stereochemistry at carbon, forming a
mixture of two isomers of [Ir(C6H10F)Cl(Br)(CO)-
(PMe3)2].27
HF/py reagent. HF is extremely corrosive to human tissue.34
)
resulted in formation of trans-2-fluorocyclohexanol,35 which
reacted with PBr3 to yield cis-1-bromo-2-fluorocyclohexane.36
The other chemicals were commercial materials used without
further purification. Microanalyses were performed by the
University of Halle microanalytical laboratory using a CHNS-
932 (LECO) and Vario EL (elementar Analysensysteme)
elemental analyzer, respectively. The 1H, 13C, 19F, and 31P
NMR spectra were obtained with Varian Unity 500, VXR 400,
and Gemini 200 spectrometers (1H at 500/400/200 MHz).
Solvent signals (1H, 13C) were used as internal standards. δ-
(19F) and δ(31P) are relative to PhCF3 (0.05% in C6D6, δ -63.9)
and H3PO4 (85%, δ 0), respectively. In higher order multiplets
N gives the distance between the most intense lines. Ther-
moanalytic investigations were performed on a STA 409C
(Netzsch) instrument under an argon atmosphere. A CP9000
(Chrompack) chromatograph was used for gas chromato-
graphic analyses.
The remarkable activation of â-C-F bonds described
in this work can be explained by alkylcobaloximes of
type 13 (Scheme 6) as (unseen) intermediates. When
these intermediates are presumed, the formation of
products observed here can be understood by cleavage
3.2. L-[Co]-/L-[Co]-H (L ) P P h 3, p y, 4-(t-Bu )p y,
3-F p y). To a solution of L-[Co]-Cl (1.3 mmol) in methanolic
(28) March, J . Advanced Organic Chemistry: Reactions, Mecha-
nisms, and Structure, 4th ed.; Wiley: New York, 1992.
(29) Schrauzer, G. N.; Windgassen, R. J . Chem. Ber. 1966, 99, 602-
610.
(22) Cambridge Structural Database (CSD), Cambridge Crystal-
lographic Data Centre, University Chemical Laboratory, Cambridge,
U.K.
(23) Attia, W. M.; Zangrando, E.; Randaccio, L.; Antolini, L.; Lopez,
C. Acta Crystallogr. 1989, C45, 1500-1503.
(24) Schneider, H.-J .; Gschwendtner, W.; Heiske, D.; Hoppen, V.;
Thomas, F. Tetrahedron 1977, 33, 1769-1773.
(25) Marzilli, L. G.; Summers, M. F.; Zangrando, E.; Bresciani-
Pahor, N.; Randaccio, L. J . Am. Chem. Soc. 1986, 108, 4830-4838.
(26) (a) J ensen, F. R.; Madan, V.; Buchanan, D. H. J . Am. Chem.
Soc. 1970, 92, 1414-1416. (b) J ensen, F. R.; Madan, V.; Buchanan, D.
H. J . Am. Chem. Soc. 1971, 93, 5283-5284. (c) Tada, M.; Ogawa, H.
Tetrahedron Lett. 1973, 2639-2642. (d) Shinozaki, H.; Ogawa, H.;
Tada, M. Bull. Chem. Soc. J pn. 1976, 49, 775-778. (e) Branchaud, B.
P.; Yu, G.-X. Organometallics 1991, 10, 3795-3797.
(27) Labinger, J . A.; Osborn, J . A. Inorg. Chem. 1980, 19, 3230-
3236.
(30) Ohta, Y.; Kohda, H.; Kimoto, H.; Okano, T.; Kawazoe, Y. Chem.
Pharm. Bull. 1988, 36, 2410-2416.
(31) Wilson, C. E.; Lucas, H. J . J . Am. Chem. Soc. 1936, 58, 2396-
2402.
(32) Papageorgiou, C.; Borer, X.; French, R. R. Biorg. Med. Chem.
Lett. 1994, 4, 267-272.
(33) Welch, J . T.; Seper, K. W. J . Org. Chem. 1988, 53, 2991-2999.
(34) Meshri, D. T. In Chemistry of Organic Fluorine Compounds II;
Hudlicky, M., Pavlath, A. E., Eds.; ACS Monograph 187; American
Chemical Society: Washington, DC, 1995; pp 25-38.
(35) Ando, T.; Ishihara, T.; Ohtani, E.; Sawada, H. J . Org. Chem.
1981, 46, 4446-4450.
(36) Olah, G. A.; Li, X.-Y.; Wang, Q.; Prakash, G. K. S. Synthesis
1993, 7, 693-699.

4882 Organometallics, Vol. 22, No. 24, 2003
Galinkina et al.
1
2
NaOH (0.15 M, 100 mL) was added a solution of NaBH4 (75
mg, 2.0 mmol) in methanolic NaOH (0.15 M, 25 mL) dropwise,
and the mixture was stirred for about 1-2 h at room temper-
ature to give deep blue (L ) PPh3) and green (L ) py, 4-(t-
Bu)py, 3-Fpy) solutions of L-[Co]-. To L-[Co]-Cl (L ) py,
4-(t-Bu)py, 3-Fpy) (1.3 mmol) in methanol (50 mL) was added
NaBH4 (75 mg, 2.0 mmol) in small portions at -30 °C, and
the mixture was stirred for a further 30 min at this temper-
ature to give a green suspension of L-[Co]-/L-[Co]-H.
3.3. P h 3P -[Co]-CH2CH2CH2F (3). To Ph3P-[Co]- (pre-
pared from 1.3 mmol of Ph3P-[Co]-Cl) in methanolic NaOH
(125 mL, 0.15 M) was added BrCH2CH2CH2F (367 mg, 2.6
mmol) in MeOH (20 mL) dropwise. After the mixture had
turned yellow (about 15 min), stirring was continued for 30
min and water (100 mL) was added. Then the reaction mixture
was neutralized (pH 7-8) with solid CO2. After 30 min the
orange precipitate was filtered off, washed with water (3 × 5
mL) and diethyl ether (3 × 5 mL), and dried in vacuo. Yield:
438 mg (65%). Anal. Calcd for C29H35CoFN4O4P (612.53): C,
(t, J F,C ) 240.7 Hz, CHF2), 125.3 (d, J F,C ) 18.2 Hz, 4-CH of
3-Fpy), 125.9 (d, 3J F,C ) 5.3 Hz, 5-CH of 3-Fpy), 139.0 (d, 2J F,C
4
) 29.8 Hz, 2-CH of 3-Fpy), 146.2 (s, J C,F ) 3.9 Hz, 6-CH of
1
3-Fpy), 150.9 (s, CdN), 160.0 (d, J F,C ) 255.5 Hz, 3-CH of
3-Fpy). 19F NMR (188 MHz, CDCl3): δ -101.8 (“td”, J F,H
)
2
3
58.5 Hz, J F,H ) 22.0 Hz, CHF2), -122.2 (s, CF of 3-Fpy).
3.5. Rea ction s of p y*-[Co]- w ith Br CH2CH2F , Yield in g
p y*-[Co]-CH2CH2OMe (p y* ) p y (5a ), 4-(t-Bu )p y (5b),
3-F p y (5c)). To py*-[Co]- (prepared from 1.3 mmol of py*-
[Co]-Cl; py* ) py, 4-(t-Bu)py, 3-Fpy) in methanol (125 mL)
or in methanolic NaOH (0.15 M, 125 mL) was added a solution
of BrCH2CH2F (330 mg, 2.6 mmol) in MeOH (20 mL) dropwise
at -30 °C. Then the solution was warmed to room tempera-
ture. After the mixture had turned orange (about 30 min),
stirring was continued for 30 min and water (100 mL) was
added. Then the reaction mixture was neutralized (pH 7-8)
with solid CO2. The solution was extracted with CH2Cl2. The
combined organic phases were dried over Na2SO4, and solvent
was completely evaporated in vacuo. The residue was taken
up in CH2Cl2 (5 mL), and diethyl ether (7 mL) was added,
yielding an orange microcrystalline precipitate, which was
filtered off, washed with diethyl ether (3 × 5 mL), and dried
in vacuo.
1
55.17; H, 5.97. Found: C. 55.17; H, 5.97. H NMR (400 MHz,
CDCl3): δ 1.23 (m, 2H, 1-CH2), 1.69 (m, 2H, 2-CH2), 1.80 (d,
3
5J P,H ) 3.30 Hz, 12H, CH3 of dmgH), 4.32 (“dt”, J H,H ) 6.49
2
Hz, J F,H ) 47.65 Hz, 3-CH2), 7.24-7.53 (m, 15H, C6H5). 13C
NMR (100 MHz, CDCl3): δ 11.6 (s, CH3 of dmgH), 30.2 (d,
2J F,C ) 15.8 Hz, 2-CH2), 83.3 (dd, 1J F,C ) 167.3 Hz, 4J P,C ) 10.1
Hz, 3-CH2), 128.3 (d, 3J P,C ) 8.7 Hz, m-C), 130.0 (d, 4J P,C ) 2.1
5a (py* ) py): yield (neutral/alkaline medium) 133/206 mg
1
(24/37%). H NMR (200 MHz, CDCl3): δ 1.53 (m, N ) 16.21
Hz, 2H, 1-CH2), 2.08 (s, 12H, CH3 of dmgH), 3.01 (m, N ) 16.40
Hz, 2H, 2-CH2), 3.17 (s, 3H, OCH3), 7.27 (m, 2H, 3/5-CH of
py), 7.69 (m, 1H, 4-CH of py), 8.52 (“d”, br., N ) 5.08 Hz, 2H,
2/6-CH of py). 13C NMR (100 MHz, CDCl3): δ 11.9 (s, CH3 of
dmgH), 57.7 (s, OCH3), 74.2 (s, 2-CH2), 125.2 (s, 3/5-CH of py),
137.5 (s, 4-CH of py), 149.6 (s, CdN), 149.8 (s, 2/6-CH of py).
1
2
Hz, p-C), 130.4 (d, J P,C ) 28.2 Hz, i-C), 133.8 (d, J P,C ) 9.5
Hz, o-C), 148.7 (s, CdN). 19F NMR (188 MHz, CDCl3):
-215.9 (m). 31P NMR (81 MHz, CDCl3): δ 21.0 (br).
δ
3.4. p y*-[Co]-CH2CHF 2 (p y* ) p y (4a ), 4-(t-Bu )p y (4b),
3-F p y (4c)). To py*-[Co]-H/py*-[Co]- (prepared from 1.3
mmol of py*-[Co]-Cl; py* ) py, 4-(t-Bu)py, 3-Fpy) in methanol
(50 mL) was added a solution of BrCH2CHF2 (377 mg, 2.6
mmol) in MeOH (20 mL) dropwise at -30 °C. Then the solution
was warmed to room temperature. After the mixture had
turned orange (about 2 h), stirring was continued for 30 min
and water (100 mL) was added. After 30 min the orange
precipitate was filtered off, washed with water (3 × 5 mL) and
diethyl ether (3 × 5 mL), and dried in vacuo.
5b (py* ) 4-(t-Bu)py): yield (neutral/alkaline medium) 131/
1
220 mg (21/35%). H NMR (200 MHz, CDCl3): δ 1.23 (s, 9H,
CH3 of t-Bu), 1.52 (m, N ) 16.60 Hz, 2H, 1-CH2), 2.10 (s, 12H,
CH3 of dmgH), 3.03 (m, N ) 16.41 Hz, 2H, 2-CH2), 3.19 (s,
3H, OCH3), 7.23 (“d”, N ) 4.88 Hz, 2H, 3/5-CH of 4-(t-Bu)py),
8.37 (m, N ) 6.80 Hz, 2H, 2/6-CH of 4-(t-Bu)py). 13C NMR (100
MHz, CDCl3): δ 11.9 (s, CH3 of dmgH), 30.3 (s, CH3 of t-Bu),
34.7 (s, C of t-Bu), 57.6 (s, OCH3), 74.2 (s, 2-CH2), 122.3 (s,
3/5-CH of 4-(t-Bu)py), 149.3 (s, 2/6-CH of 4-(t-Bu)py), 149.5 (s,
CdN), 161.7 (s, 4-C of 4-(t-Bu)py).
4a (py* ) py): yield 310 mg (55%). Anal. Calcd for C15H22
-
CoF2N5O4 (433.30): C, 41.58; H, 5.12. Found: C, 41.22; H, 5.35.
3
1H NMR (200 MHz, CDCl3): δ 1.29 (“td”, J H,F ) 21.83 Hz,
5c (py* ) 3-Fpy): yield (neutral/alkaline medium) 52/116
mg (9/20%). 1H NMR (200 MHz, CDCl3): δ 1.56 (m, N ) 16.02
Hz, 2H, 1-CH2), 2.08 (s, 12H, CH3 of dmgH), 2.99 (m, N ) 16.22
Hz, 2H, 2-CH2), 3.18 (s, 3H, OCH3), 7.30 (m, 1H, 4-CH of
3-Fpy), 7.43 (m, 1H, 5-CH of 3-Fpy), 8.40 (“d”, N ) 5.08 Hz,
1H. 6-CH of 3-Fpy), 8.47 (m, 1H, 2-CH of 3-Fpy). 13C NMR-
(100 MHz, CDCl3): δ 11.8 (s, CH3 of dmgH), 57.7 (s, OCH3),
74.2 (s, 2-CH2), 124.9 (d, 2J F,C ) 18.1 Hz, 4-CH of 3-Fpy), 125.9
3J H,H ) 5.01 Hz, 2H, CH2), 2.13 (s, 12H, CH3 of dmgH), 5.62
2
3
(“tt”, J H,F ) 58.89 Hz, J H,H ) 4.98 Hz, 1H, CHF2), 7.27 (m,
2H, 3/5-CH of py), 7.53 (m, 1H, 4-CH of py), 8.49 (“d”, N )
4.88 Hz, 2H, 2/6-CH of py). 13C NMR (100 MHz, CDCl3): δ
12.1 (s, CH3 of dmgH), 120.9 (t, 1J F,C ) 240.5 Hz, CHF2), 125.4
(s, 3/5-CH of py), 137.9 (s, 4-CH of py), 149.8 (s, 2/6-CH of py),
150.6 (s, CdN). 19F NMR (188 MHz, CDCl3): δ -101.6 (“td”,
3
2J F,H ) 62.1 Hz, J F,H ) 21.9 Hz).
3
2
(d, J F,C ) 5.0 Hz, 5-CH of 3-Fpy), 139.0 (d, J F,C ) 29.2 Hz,
2-CH of 3-Fpy), 146.2 (s, 4J C,F ) 4.0 Hz, 6-CH of 3-Fpy), 150.1
(s, CdN), 160.1 (d, 1J F,C ) 256.5 Hz, 3-CH of 3-Fpy). 19F NMR-
(188 MHz, CDCl3): δ -122.8 (m).
4b (py* ) 4-(t-Bu)py): yield 363 mg (57%). Anal. Calcd for
C
19H30CoF2N5O4 (489.41): C, 46.63; H, 6.19. Found: C, 46.39;
H, 6.30. 1H NMR (400 MHz, CDCl3): δ 1.24 (s, 9H, CH3 of
3
3
t-Bu), 1.28 (“td”, J H,F ) 22.05 Hz, J H,H ) 4.98 Hz, 2H, CH2),
3.6. Rea ction s of p y*-[Co]-H/p y*-[Co]- w ith TfOCH2-
CMe2F , Yield in g p y*-[Co]-CHdCMe2 (p y* ) p y (6a ),
3-F p y (6b)). To py*-[Co]-H/py*-[Co]- (prepared from 1.3
mmol of py*-[Co]-Cl; py* ) py, 3-Fpy) in methanol (50 mL)
was added a solution of TfOCH2CMe2F (583 mg, 2.6 mmol) in
MeOH (20 mL) dropwise at -30 °C. Then the solution was
warmed to room temperature. After the mixture had turned
orange (about 16 h), stirring was continued for 30 min and
water (100 mL) was added. After 30 min the orange precipitate
was filtered off, washed with water (3 × 5 mL) and diethyl
ether (3 × 5 mL), and dried in vacuo.
2
3
2.13 (s, 12H, CH3 of dmgH), 5.63 (“tt”, J H,F ) 58.87 Hz, J H,H
) 5.19 Hz, 1H, CHF2), 7.24 (m, N ) 6.49 Hz, 2H, 3/5-CH of
4-(t-Bu)py), 8.34 (“d”, N ) 6.48 Hz, 2H, 2/6-CH of 4-(t-Bu)py).
13C NMR (100 MHz, CDCl3): δ 12.0 (s, CH3 of dmgH), 30.1 (s,
1
CH3 of t-Bu), 34.8 (s, C of t-Bu), 121.1 (t, J F,C ) 240.9 Hz,
CHF2), 122.6 (s, 3/5-CH of 4-(t-Bu)py), 149.4/150.6 (s/s, 2/6-
CH of 4-(t-Bu)py/CdN), 162.5 (s, 4-C of 4-(t-Bu)py). 19F NMR
2
3
(188 MHz, CDCl3): δ -101.4 (“td”, J F,H ) 58.5 Hz, J F,H
)
22.0 Hz).
4c (py* ) 3-Fpy): yield 223 mg (38%). Anal. Calcd for
C
15H21CoF3N5O4 (451.29): C, 39.92; H, 4.69. Found: C, 40.40;
H, 4.70. 1H NMR (200 MHz, CDCl3): δ 1.33 (“dt”, 3J H,F ) 21.68
6a (py* ) py): yield 83 mg (15%). 1H NMR (200 MHz,
CDCl3): δ 1.66 (s, 3H, CH3), 1.74 (s, 3H, CH3), 2.07 (s, 12H,
CH3 of dmgH), 5.29 (s, 1H, dCH), 7.29 (m, 2H, 3/5-CH of py),
7.65 (m, 1H, 4-CH of py), 8.63 (“d”, br, N ) 4.84 Hz, 2H, 2/6-
CH of py). 13C NMR (100 MHz, CDCl3): δ 11.9 (s, CH3 of
dmgH), 19.2 (s, CH3), 28.8 (s, CH3), 125.2 (s, 3/5-CH of py),
3
Hz, J H,H ) 4.88 Hz, 2H, CH2), 2.14 (s, 12H, CH3 of dmgH),
2
3
5.62 (“tt”, J H,F ) 58.70 Hz, J H,H ) 5.01 Hz, 1H, CHF2), 7.46
(m, 1H, 4-CH of 3-Fpy), 7.52 (m, 1H, 5-CH of 3-Fpy), 8.37 (“d”,
N ) 5.28 Hz, 1H, 6-CH of 3-Fpy), 8.44 (m, 1H, 2-CH of 3-Fpy).
13C NMR (100 MHz, CDCl3): δ 12.3 (s, CH3 of dmgH), 120.7

(Fluoroalkyl)- and (Fluorocycloalkyl)cobaloximes
Organometallics, Vol. 22, No. 24, 2003 4883
136.3 (s, dCMe2), 137.5 (s, 4-CH of py), 149.8 (s, CdN), 150.0
(s, 2/6-CH of py).
CDCl3): δ 1.23 (s, 9H, CH3 of t-Bu), 1.38-1.62 (m, 7H, CH/
CH2 of c-pent), 2.08/2.09 (s/s, 12H, CH3 of dmgH), 4.83 (d, 2J F,H
) 53.32 Hz, 1H, CHF), 7.21 (“d”, N ) 6.66 Hz, 2H, 3/5-CH of
4-(t-Bu)py), 8.40 (“d”, N ) 6.41 Hz, 2H, 2/6-CH of 4-(t-Bu)py).
13C NMR (100 MHz, CDCl3): δ 11.9 (s, CH3 of dmgH), 19.2 (s,
5-C of c-pent), 28.5 (s, 4-C of c-pent), 30.1 (s, CH3 of t-Bu), 30.7
6b (py* ) 3-Fpy): yield 29 mg (5%). 1H NMR (200 MHz,
CDCl3): δ 1.65 (s, 3H, CH3), 1.74 (s, 3H, CH3), 2.09 (s, 12H,
CH3 of dmgH), 5.25 (s, 1H, dCH), 7.24-7.45 (m, 2H, 4/5-CH
of 3-Fpy), 8.50 (“d”, N ) 4.69 Hz, 1H, 6-CH of 3-Fpy), 8.58 (m,
2
1H, 2-CH of 3-Fpy). 13C NMR (100 MHz, CDCl3): δ 12.9 (s,
(d, J F,C ) 24.9 Hz, 3-C of c-pent), 34.7 (s, C of t-Bu), 101.5 (d,
1J F,C ) 173.2 Hz, CHF), 122.4 (s, 3/5-CH of 4-(t-Bu)py), 149.3
(s, 2/6-CH of 4-(t-Bu)py), 149.8/150.5 (s/s, CdN), 161.9 (s, 4-C
of 4-(t-Bu)py). 19F NMR (188 MHz, CDCl3): δ -177.1 (m).
3.8. p y-[Co]-C6H11 (8) a n d p y*-[Co]-C6H9 (9). Complex
8 was prepared from py-[Co]- (prepared from 1.3 mmol of py-
[Co]-Cl) and cyclohexyl bromide (424 mg, 2.6 mmol) as
described for complexes 7. Yield: 256 mg (42%). 1H NMR (400
MHz, CDCl3): δ 0.78-2.26 (m, 11H, CH/CH2 of c-hex), 2.09
(s, 12H, CH3 of dmgH), 7.19 (m, 2H, 3/5-CH of py), 7.65 (m,
2
CH3 of dmgH), 20.1 (s, CH3), 29.6 (s, CH3), 125.9 (d, J F,C
)
3
17.8 Hz, 4-CH of 3-Fpy), 126.8 (d, J F,C ) 5.8 Hz, 5-CH of
2
3-Fpy), 137.5 (s, dCMe2), 140.0 (d, J F,C ) 29.4 Hz, 2-CH of
3-Fpy), 147.3 (s, 6-CH of 3-Fpy), 151.1 (s, CdN), 161.1 (d, 1J F,C
) 255.7 Hz, 3-CH of 3-Fpy). 19F NMR (188 MHz, CDCl3): δ
-122.9 (s).
3.7. (2-F lu or ocycloh exyl)- a n d (2-F lu or ocyclop en tyl)-
coba loxim es p y*-[Co]-R (7a ,b a n d 10a ,b). To py*-[Co]-
H/py*-[Co]- (1.3 mmol) in MeOH (50 mL) was added a
solution of trans-1-bromo-2-fluorocyclohexane, cis-1-bromo-2-
fluorocyclohexane, and trans-1-bromo-2-fluorocyclopentane (2.6
mmol), respectively, in MeOH (20 mL) dropwise at -30 °C.
Stirring was continued for 1 h at this temperature and for 16
(7) and 6 h (10), respectively, at room temperature. Then water
(100 mL) was added. The product that precipitated was filtered
off, washed with water (3 × 10 mL) and diethyl ether (3 × 10
mL), and dried in vacuo.
1H, 4-CH of py), 8.55 (“d”, N ) 4.77 Hz, 2H, 2/6-CH of py). 13
C
NMR (100 MHz, CDCl3): δ 11.9 (s, CH3 of dmgH), 27.3 (s, 4-C
of c-hex), 29.7 (s, 3/5-C of c-hex), 36.9 (s, 2/6-C of c-hex), 50.4
(br, 1-CH of c-hex), 125.1 (s, 3/5-CH of py), 137.3 (s, 4-CH of
py), 149.6/150.1 (s/s, 2/6-CH of py/CdN).
Complex 9 (py*-[Co]-C6H9, C6H9 ) cyclohex-1-enyl) in a
mixture with 7a (total yield: ca. 3%) was prepared from py-
[Co]- and cis-1-bromo-2-fluorocyclohexane analogously to the
procedure described for complexes 7. Signals of 7a were as
reported. Data for 9 are as follows. 1H NMR (400 MHz,
CDCl3): δ 1.29-1.97 (m, 8H, CH/CH2), 2.07 (s, 12H, CH3 of
dmgH), 5.02 (s, br, 1H, dCH), 7.25 (m, 2H, 3/5-CH of py), 7.67
(m, 1H, 4-CH of py), 8.62 (“d”, N ) 5.29 Hz, 2H, 2/6-CH of py).
13C NMR (100 MHz, CDCl3): δ 12.0 (s, CH3 of dmgH), 23.4/
26.4/28.5/33.4 (s/s/s/s, 3-6-CH2), 124.8 (s, dCH), 150.02 (s,
2/6-C of py), 150.04 (s, CdN) (3,5-/4-C of py at 125.2/137.4 ppm
are overlapped with corresponding signals of 7a ). NMR data
are in accordance with those given in the literature.37
3.9. Cr ysta llogr a p h ic Stu d ies. Intensity data for 3 were
collected on a STOE-STADI4 four-circle diffractometer and for
4a , 7b, and 7b‚CH2Cl2 on a STOE IPDS diffractometer with
Mo KR radiation (0.710 73 Å, graphite monochromator). A
summary of crystallographic data, data collection parameters,
and refinement parameters is given in Table 6. Absorption
corrections were not applied. The structures were solved by
direct methods with SHELXS-8638 and refined using full-
matrix least-squares routines against F2 with SHELXL-93.38
Non-hydrogen atoms were refined with anisotropic and hy-
drogen atoms with isotropic displacement parameters. The
hydrogen atom positions were calculated and allowed to ride
on their corresponding atoms. The hydrogen atoms in the
O-H‚‚‚O bridges in 3 and 7b were found in the difference
Fourier map. In 4a the CH2CHF2 group is disordered over
three positions with 40, 35, and 25% site occupancies. For the
refinement the bond lengths C9-C10, C10-F1, and C10-F2
were fixed at 1.330(8) and 1.510(8) Å. In 7b‚CH2Cl2 the
fluorine atom is disordered over two positions with a major
(F1, 68%) and a minor (F1a, 38%) site occupancy.
7a (py* ) py, R ) cis-2-fluorocyclohexyl): yield 214 mg
(35%). Anal. Calcd for C19H29CoFN5O4 (469.40): C, 48.62; H,
6.23. Found: C, 48.32; H, 6.01. 1H NMR (200 MHz, CDCl3): δ
1.28-1.78 (m, 9H, CH/CH2 of c-hex), 2.10/2.12 (s/s, 12H, CH3
2
of dmgH), 4.70 (“d”, J F,H ) 47.49 Hz, 1H, CHF), 7.24 (m, 2H,
3/5-CH of py), 7.65 (m, 1H, 4-CH of py), 8.54 (“d”, N ) 5.08
Hz, 2H, 2/6-CH of py). 13C NMR (100 MHz, CDCl3): δ 11.97/
12.01 (s/s, CH3 of dmgH), 20.9 (s, 5-CH2 of c-hex), 29.2/29.6
2
(s/s, 4-CH2/6-CH2 of c-hex), 34.6 (d, J F,C ) 24.1 Hz, 3-CH2 of
c-hex), 96.4 (d, 1J F,C ) 171.1 Hz, CHF), 125.2 (s, 3/5-CH of py),
137.4 (s, 4-CH of py), 150.0 (s, 2/6-CH of py), 150.1/150.9 (s/s,
CdN). 19F NMR (188 MHz, CDCl3): δ -189.2 (m).
7b (py* ) 4-(t-Bu)py, R ) cis-2-fluorocyclohexyl): yield 273
mg (40%). Anal. Calcd. for C23H37CoFN5O4 (525.51): C, 52.57;
H, 7.10. Found: C, 52.64; H, 6.85. 1H NMR (400 MHz,
CDCl3): δ 1.22 (s, 9H, C(CH3)3), 1.31-1.68 (m, 9H, CH/CH2 of
2
c-hex), 2.10/2.11 (s/s, 12H, CH3 of dmgH), 4.70 (“d”, J F,H
)
47.26 Hz, 1H, CHF), 7.19 (“d”, N ) 4.03, 2H, 3/5-CH of 4-(t-
Bu)py), 8.37 (“d”, N ) 4.03 Hz, 2H, 2/6-CH of 4-(t-Bu)py). 13C
NMR (100 MHz, CDCl3): δ 11.96/12.01 (s/s, CH3 of dmgH),
20.9 (s, 5-CH2 of c-hex), 29.2/29.5 (s/d, 3J F,C ) -/2.9 Hz, 4-CH2/
2
6-CH2 of c-hex), 30.1 (s, C(CH3)3), 34.6 (d, J F,C ) 24.0 Hz,
3-CH2 of c-hex), 34.7 (s, C(CH3)3), 46.4 (br, 1-CH of c-hex), 96.4
1
(d, J F,C ) 170.7 Hz, CHF), 122.3 (s, 3/5-CH of 4-(t-Bu)py),
149.4 (s, 2/6-CH of 4-(t-Bu)py), 149.8/150.6 (s/s, CdN), 161.7
(s, 4-C of 4-(t-Bu)py). 19F NMR (188 MHz, CDCl3): δ -187.7
(m). Temperature dependence: 1H NMR (500 MHz, C6D5CD3;
CH3 of dmgH): -80 °C, δ 1.899/1.837 (∆δ ) 31.9 Hz); -50 °C,
δ 1.781/1.729 (∆δ ) 25.7 Hz); -10 °C, δ 1.819/1.782 (∆δ ) 18.8
Hz); +27 °C, δ 1.852/1.825 (∆δ ) 13.7 Hz); +50 °C, δ 1.869/
1.847 (∆δ ) 11.1 Hz); +85 °C, δ 1.889/1.874 (∆δ ) 7.6 Hz);
+99 °C, δ 1.896/1.883 (∆δ ) 6.5 Hz).
3.10. Com p u ta tion a l Deta ils. All reported DFT calcula-
tions were performed by employing the Gaussian98 program39
using the hybrid functional B3LYP.40 An effective core poten-
tial (ECP) was used to represent the innermost electrons of
the cobalt atom.41,42 Two different basis sets were used
throughout the investigations. Geometries of complexes, in-
termediates, and transition states were optimized using the
LANL2DZ basis set41,43 (denoted as BS1) without imposing any
symmetry restrictions. The localized stationary points were
identified exactly as equilibrium structures and transition
states, respectively, at this level of approximation by the
curvature ot the potential-energy surface at these points,
10a (py* ) py, R ) cis-2-fluorocyclopentyl): yield 266 mg
(45%). Anal. Calcd for C18H27CoFN5O4 (455.38): C, 47.48; H,
5.98. Found: C, 47.57; H, 5.74. 1H NMR (400 MHz, CDCl3): δ
1.18-1.66 (m, 7H, CH/CH2 of c-pent), 2.06/2.07 (s/s, 12H, CH3
2
of dmgH), 4.82 (d, J F,H ) 53.41 Hz, 1H, CHF), 7.44 (m, 2H,
3/5-CH of py), 7.67 (m, 1H, 4-CH of py), 8.55 (“d”, N ) 4.88
Hz, 2H, 2/6-CH of py). 13C NMR (100 MHz, CDCl3): δ 11.8 (s,
CH3 of dmgH), 19.1 (s, 5-C of c-pent), 28.5 (s, 4-C of c-pent),
30.6 (d, 2J F,C ) 24.4 Hz, 3-C of c-pent), 41.9 (br, 1-CH of c-pent),
101.2 (d, 1J F,C ) 173.6 Hz, CHF), 125.1 (s, 3/5-CH of py), 137.5
(s, 4-CH of py), 149.9 (s, 2/6-CH of py), 150.0/150.6 (s/s,
CdN). 19F NMR (188 MHz, CDCl3): δ -177.1 (m).
(37) Stang, P. J .; Datta, A. K. J . Am. Chem. Soc. 1989, 111, 1358-
1363.
(38) Sheldrick, G. M. SHELXS-86, SHELXS-93. Programs for
Crystal Structure Determination; University of Go¨ttingen, Go¨ttingen,
Germany, 1986, 1993.
10b (py* ) 4-(t-Bu)py, R ) cis-2-fluorocyclopentyl): yield
313 mg (47%). Anal. Calcd for C22H35CoFN5O4 (511.48): C,
1
51.75; H, 6.90. Found: C, 51.66; H, 6.81. H NMR (400 MHz,

4884 Organometallics, Vol. 22, No. 24, 2003
Ta ble 6. Cr ysta l Da ta a n d Str u ctu r e Refin em en t for 3, 4a , 7b, a n d 7b‚CH2Cl2
Galinkina et al.
3
4a
7b
7b‚CH2Cl2
empirical formula
fw
C29H35CoFN4O4P
612.51
C15H22CoF2N5O4
433.31
C23H37CoFN5O4
525.51
C24H39Cl2CoFN5O4
610.43
T, K
293(2)
293(2)
203(2)
293(2)
cryst syst
space group
a, Å
b, Å
c, Å
orthorhombic
P212121
10.757(2)
14.748(1)
18.520(3)
orthorhombic
P212121
9.676(2)
12.381(2)
15.625(3)
orthorhombic
Pna21
16.124(2)
13.225(2)
12.280(2)
monoclinic
Cc
8.881(2)
16.570(3)
19.647(4)
92.71(3)
2888(1)
4
1.404
0.824
1280
â, deg
V, Å3
Z
2938.2(8)
4
1.385
0.685
1280
1871.9(6)
4
1.538
0.967
896
2618.6(7)
4
1.333
0.699
1112
F
calc, g/cm3
µ(Mo KR), mm-1
F(000)
scan range, deg
no. of rflns collected
no. of indep rflns
no. of obsd rflns
no. of params refined
goodness of fit on F2
final R (I > 2σ(I))
1.77-26.02
2.10-26.15
1.99-25.99
2.08-25.90
9216
14 126
15 166
11 064
5103
4690
370
1.065
R1 ) 0.0354
wR2 ) 0.0934
R1 ) 0.0413
wR2 ) 0.1030
0.386/-0.240
3566
2942
257
1.043
R1 ) 0.0635
wR2 ) 0.1568
R1 ) 0.0743
wR2 ) 0.1630
1.098/-0.387
4970
4116
315
1.011
R1 ) 0.0359
wR2 ) 0.0810
R1 ) 0.0478
wR2 ) 0.0867
0.331/-0.234
5043
4121
351
1.073
R1 ) 0.0433
wR2 ) 0.0942
R1 ) 0.0589
wR2 ) 0.1022
0.524/-0.526
R (all data)
largest diff peak/hole, e Å-3
corresponding to the eigenvalues of the analytical Hessian.
Zero-point vibrational energies were found to affect the
calculated activation potential energies ∆Eq to only a minor
extent. Therefore, uncorrected activation potential energies are
reported.
To obtain more reliable energetics, single-point energy
calculations at the B3LYP level, using the Stuttgart/Dresden
effective core potential (SDD42) and the associated basis set
for Co and 6-31G(d) basis sets for main group elements
(denoted as BS2), have been performed at the B3LYP/BS1
optimized geometries. Furthermore, the structure of complex
11a was fully optimized using basis set BS2 without imposing
any symmetry restrictions. The two fully optimized structures
of 11a (B3LYP/BS1 vs B3LYP/BS2) proved to be very similar,
exhibiting the reliability of structures that were obtained using
the B3LYP/BS1 level of theory. Cartesian coordinates of atom
positions of all localized stationary points are provided as
Supporting Information.
Ack n ow led gm en t. This work was supported by the
Deutsche Forschungsgemeinschaft and by the Fonds der
Chemischen Industrie. Gifts of chemicals by Merck
(Darmstadt) are gratefully acknowledged.
(39) Frisch, M. J .; Trucks, G. W.; Schlegel, H. B.; Scuseria, G. E.;
Robb, M. A.; Cheeseman, J . R.; Zakrzewski, V. G.; Montgomery, J . A.,
J r.; Stratmann, R. E.; Burant, J . C.; Dapprich, S.; Millam, J . M.;
Daniels, A. D.; Kudin, K. N.; Strain, M. C.; Farkas, O.; Tomasi, J .;
Barone, V.; Cossi, M.; Cammi, R.; Mennucci, B.; Pomelli, C.; Adamo,
C.; Clifford, S.; Ochterski, J .; Petersson, G. A.; Ayala, P. Y.; Cui, Q.;
Morokuma, K.; Malick, D. K.; Rabuck, A. D.; Raghavachari, K.;
Foresman, J . B.; Cioslowski, J .; Ortiz, J . V.; Stefanov, B. B.; Liu, G.;
Liashenko, A.; Piskorz, P.; Komaromi, I.; Gomperts, R.; Martin, R. L.;
Fox, D. J .; Keith, T.; Al-Laham, M. A.; Peng, C. Y.; Nanayakkara, A.;
Gonzalez, C.; Challacombe, M.; Gill, P. M. W.; J ohnson, B. G.; Chen,
W.; Wong, M. W.; Andres, J . L.; Head-Gordon, M.; Replogle, E. S.;
Pople, J . A. Gaussian 98, revision A.3; Gaussian, Inc.: Pittsburgh, PA,
1998.
(40) (a) Becke, A. D. Phys. Rev. A 1988, 38, 3098-3100. (b) Becke,
A. D. J . Chem. Phys. 1993, 98, 5648-5652. (c) Lee, C.; Yang, W.; Parr,
R. G. Phys. Rev. B 1988, 37, 785-789. (d) Stephens, P. J .; Devlin, F.
J .; Chabalowski, C. F.; Frisch, M. J . J . Phys. Chem. 1994, 98, 11623-
11627.
(41) Hay, P. J .; Wadt, W. R. J . Chem. Phys. 1985, 82, 299-310.
(42) Dolg, M.; Wedig, U.; Stoll, H.; Preuss, H. J . Chem. Phys. 1987,
86, 866-872.
(43) Dunning, T. H., J r.; Hay, P. J . In Modern Theoretical Chemistry;
Schaefer, H. F., III., Ed.; Plenum: New York, 1976; pp 1-28.
Su p p or tin g In for m a tion Ava ila ble: Complete tables of
atomic coordinates, H atom parameters, bond distances, bond
angles, and anisotropic displacement parameters for 3, 4a , 7b,
and 7b‚CH2Cl2 and complete tables of Cartesian coordinates
of atom positions calculated for equilibrium structures and
transition states (see Table 5) of 11 and 12. This material is
available free of charge via the Internet at http://pubs.acs.org.
Crystallographic data (excluding structure factors) for the
structures reported in this paper have been deposited at the
Cambridge Crystallographic Data Center as Supplementary
Publication Nos. CCDC-219022 (3), CCDC-219023 (4a ), CCDC-
219024 (7b), and CCDC-219025 (7b‚CH2Cl2). Copies of the
data can be obtained free of charge on application to the CCDC,
12 Union Read, Cambridge CB2 1EZ, U.K. (fax, +44-1223-
336033; e-mail, deposit@ccdc.cam.ac.uk).
OM030525A