Improved synthesis of [Mn(CO)5OCIO3], a versatile reagent for the preparation of cationic (Polyene)manganese(I) complexes. Crystal structure of [(η4-1,5-cyclooctadiene)Mn(CO)4] CIO4

Article abstract of DOI:10.1021/om9805739

The title complex is synthesized in one step from [Mn₂(CO)₁₀] and is used to prepare cationic [(η⁴-diene)Mn(CO)₄]⁺ and [(η⁶-triene)Mn(CO)₃]⁺ complexes, including [(η⁴-1,5-cyclooctadiene)Mn(CO)₄]CIO₄, for which an X-ray crystal structure is reported. The kinetics of [(η⁴-norbornadiene)Mn(CO)₄]CIO₄ conversion to cis-[(CH₃CN)₂Mn(CO)₄]⁺ are also studied.

Full text of DOI:10.1021/om9805739

5586
Organometallics 1998, 17, 5586-5590
Notes
Im p r oved Syn th esis of [Mn (CO)5OClO3], a Ver sa tile
Rea gen t for th e P r ep a r a tion of Ca tion ic
(P olyen e)m a n ga n ese(I) Com p lexes. Cr ysta l Str u ctu r e of
[(η4-1,5-Cycloocta d ien e)Mn (CO)4]ClO4
Stuart C. Chaffee, J oshua C. Sutton, Clifford S. Babbitt, J onathan T. Maeyer,
Kathryn A. Guy, and Robert D. Pike*
Department of Chemistry, College of William and Mary, Williamsburg, Virginia 23187
Gene B. Carpenter
Department of Chemistry, Brown University, Providence, Rhode Island 02912
Received J uly 7, 1998
Sch em e 1
Summary: The title complex is synthesized in one step
from [Mn2(CO)10] and is used to prepare cationic [(η4-
diene)Mn(CO)4]+ and [(η6-triene)Mn(CO)3]+ complexes,
including [(η4-1,5-cyclooctadiene)Mn(CO)4]ClO4, for which
an X-ray crystal structure is reported. The kinetics of
[(η4-norbornadiene)Mn(CO)4]ClO4 conversion to cis-
[(CH3CN)2Mn(CO)4]+ are also studied.
or AlCl3.2,7 When silver perchlorate is used, an air-
stable perchlorato complex, [Mn(CO)5OClO3], can be
isolated.8 The latter functions as a stabilized 16-
electron cation. It has been shown to react with a wide
variety of donor ligands to produce [Mn(CO)5L]ClO4,8
as well as with arenes to form [(η6-arene)Mn(CO)3]-
ClO4.9 A stable trifluoromethanesulfonato (“triflate”)
complex of pentacarbonylmanganese(I) can also be pre-
pared using silver triflate.10
In tr od u ction
Manganese(I) carbonyl fragments can be potentially
used to coordinate various polyenes, thereby activating
them toward nucleophilic attack. The resulting com-
plexes include [(η6-triene)Mn(CO)3]+,1,2 [(η4-diene)Mn-
(CO)4]+,3 and [(η2-olefin)Mn(CO)5]+.4 Of these, the η6-
arene complexes are by far the best known, having
found application in organic synthesis.5,6 The arene
complexes are usually obtained through oxidation of
manganese carbonyl to [Mn(CO)5Br] using bromine
(Scheme 1), followed by halide abstraction using Ag(I)
Recently, we have shown that manganese carbonyl
is oxidized by strong acid in trifluoroacetic anhydride
(TFAA) solvent, allowing direct preparation of the arene
complexes without the need for bromine or silver.2 We
now show that, in the absence of donor ligands and
when the acid used is HClO4, [Mn(CO)5OClO3] is
produced in high yield. This species has proved useful
in the synthesis of the little-known [(η4-diene)Mn(CO)4]+
complexes as well as the arene complexes.
(1) (a) Pike, R. D.; Sweigart, D. A. Synlett 1990, 565, and references
therein. (b) Sun, S.; Dullaghan, C. A.; Carpenter, G. B.; Sweigart, D.
A.; Lee, S. S.; Chung, Y. K. Inorg. Chim. Acta 1997, 262, 213. (c) Pike,
R. D.; Sweigart, D. A. Coord. Chem. Rev., in press.
(2) J ackson, J . D.; Villa, S. J .; Bacon, D. S.; Pike, R. D.; Carpenter,
G. B. Organometallics 1994, 13, 3972, and references therein.
(3) Harris, P. J .; Knox, S. A. R.; Stone, F. G. A. J . Organomet. Chem.
1978, 148, 327.
(4) (a) Fischer, E. O.; O¨ fele, K. Angew. Chem. 1961, 73, 581. (b)
Green, M. L. H.; Nagy, P. L. I. J . Organomet. Chem. 1963, 1, 59. (c)
Green, M. L. H.; Massey, A. G.; Moelwyn-Hughes; Nagy, P. L. I. J .
Organomet. Chem. 1967, 8, 511. (d) Rybinskaya, M. I. J . Organomet.
Chem. 1990, 383, 113.
(5) (a) Miles, W. H.; Smiley, P. M.; Brinkman, H. R. J . Chem. Soc.,
Chem. Commun. 1989, 1897. (b) Miles, W. H.; Brinkman, H. R.
Tetrahedron Lett. 1992, 33, 589. (c) Krow, G. R.; Miles, W. H.; Smiley,
P. M.; Lester, W. S.; Kim, Y. J . J . Org. Chem. 1992, 57, 4040.
(6) (a) Pearson, A. J .; Bruhn, P. R.; Gouzoules, F.; Lee, S.-H. J .
Chem. Soc., Chem. Commun. 1989, 659. (b) Pearson, A. J .; Bruhn, P.
R. J . Org. Chem. 1991, 56, 7092. (c) Pearson, A. J .; Shin, H.
Tetrahedron 1992, 48, 7527. (d) Pearson, A. J .; Zhu, P. Y.; Youngs, W.
J .; Bradshaw, J . D.; McConville, D. B. J . Am. Chem. Soc. 1993, 115,
10376. (e) Pearson, A. J .; Milletti, M. C.; Zhu, P. Y. J . Chem. Soc.,
Chem. Commun. 1995, 853.
(7) [(η6-Arene)Mn(CO)3]+ has also been prepared via arene exchange
reactions: Sun, S.; Yeung, L. K.; Sweigart, D. A.; Lee, T.-Y.; Lee, S.
S.; Chung, Y. K.; Switzer, S. R.; Pike, R. D. Organometallics 1995, 14,
2613. However, with this method, the initial oxidation Mn(0) f Mn(I)
and coordination of the arene to be exchanged are still necessary.
(8) (a) Uson, R.; Riera, V.; Gimeno, J .; Laguna, M.; Gamasa, M. P.
J . Chem. Soc., Dalton Trans. 1979, 996. (b) Carriedo, G. A.; Riera, V.;
Rodriguez, M. L.; Sainz-Velicia, J . J . Polyhedron 1987, 6, 1879.
(9) (a) Lee, Y.-A.; Chung, Y. K.; Kim, Y.; J eong, J . H. Organome-
tallics 1990, 9, 2851. (b) J eong, E.; Chung, Y. K. J . Organomet. Chem.
1992, 434, 225. (c) Lee, S. S.; Lee, J .-S.; Chung, Y. K. Organometallics
1993, 12, 4640.
(10) (a) Trogler, W. C. J . Am. Chem. Soc. 1979, 101, 6459. (b)
Schmidt, S. P.; Nitschke, J .; Trogler, W. C. Inorg. Synth. 1989, 26,
113.
10.1021/om9805739 CCC: $15.00 © 1998 American Chemical Society
Publication on Web 10/29/1998

Notes
Organometallics, Vol. 17, No. 25, 1998 5587
Ta ble 1. Kin etics Da ta for th e Solvolysis of
[(η4-Nor bor n a d ien e)Mn (CO)4]ClO4, 0.509 m M, 25.0
( 0.2 °C
Sch em e 2
[CH3CN],
Ma
t1/2
s
,
104 kobs
,
105 kobs[CH3CN]-1
,
s-1
M-1 s-1
5.0
10.0
15.0
19.1b
5960
3850
2990
2180
1.16
1.80
2.32
3.18
2.32
1.80
1.55
1.66
a
b
Diluted in CH3NO2. Pure CH3CN.
product at 25.0 ( 0.2 °C was carried out under pseudo-
first-order conditions. The results are shown in Table
1. The highly linear ln(abs) vs time plots confirmed that
the reaction was first-order with respect to the NBD
complex, and the linearity of kobs vs [CH3CN] indicated
that the reaction was also first-order with respect to the
nucleophile. The average second-order rate constant
was 1.83 × 10-5 M-1 s-1. Previous studies involving
CH3CN displacement of the arene in [(η6-arene)Mn-
(CO)3]+ 11,13 and phosphite and phosphine displacement
of the diene in [(η4-diene)M(CO)4] (M ) Cr, Mo, W)14
have revealed similar dependencies. These results have
generally been interpreted via a mechanism involving
rate-limiting nucleophilic displacement of the first alk-
ene unit of the polyene, in the present case producing
[(η2-diene)Mn(CO)4(NCCH3)]+. This is followed by rapid
ligand loss and further solvent attack.
Resu lts a n d Discu ssion
The perchlorato complex [Mn(CO)5OClO3] was pre-
pared from [Mn2(CO)10] in very high yield in a single
step using HClO4 and TFAA solvent (0 °C, 1.5 h, 94%).
When scaled up to 3 g, the yield was still good (75%).
The product is precipitated as analytically pure crystals
and is readily identified by infrared spectroscopy (IR).
The analogous triflate complex, [Mn(CO)5(OS(O)2CF3)],
has been prepared using HOS(O)2CF3 in TFAA. The
triflate yield was consistently lower (42%) than that of
the perchlorate owing to difficulties in precipitation and
purification of the product. The perchlorate complex
has been used in the synthesis of cationic diene and tri-
ene complexes, as indicated in Scheme 2. The reaction
conditions used are quite mild: boiling CH2Cl2, 2-20 h.
Cationic complexes of the nonconjugated dienes,
bicyclo[2.2.1]hepta-2,5-diene (norbornadiene, NBD) and
1,5-cyclooctadiene (1,5-COD), were synthesized from
[Mn(CO)5OClO3] in good yield, the products spontane-
ously precipitating from refluxing CH2Cl2. However,
attempts to prepare the tetracarbonyl cations of conju-
gated (or readily aromatized) dienes failed in all cases.
Attempts to coordinate 1,3- or 1,4-cyclohexadiene gener-
ated sizable yields of [(η6-C6H6)Mn(CO)3]+, which was
Only a single report of [(η4-diene)Mn(CO)4]+ species
can be found in the literature.3 It involves the synthesis
of the 1,5-COD complexes of [M(CO)4]+ (M ) Mn, Re)
from [M(CO)5Cl] and AlCl3 in the presence of the diene.
These species were shown to react with hydride to
produce η1,η2-cyclooctenyl complexes. No structural
analysis was reported. Therefore, we undertook an
X-ray crystal structure determination for the COD
complex.15 Experimental details are provided in Table
2, positional and isotropic thermal parameters for the
non-hydrogen atoms are in Table 3, and important bond
lengths and angles are in Table 4. A thermal ellipsoid
drawing is shown in Figure 1. Although several d6
octahedral 1,5-COD complexes are known,16 no unsub-
stituted [(η4-1,5-COD)M(CO)4] structure has yet been
reported. The new manganese structure bears similari-
ties to the previously solved [(η4-1,5-COD)M(CO)3-
(P(OMe)3)] complexes (M ) Cr, mer isomer;17 W, fac
isomer18) and to [(η4-diCOT)Mo(CO)4]19 (diCOT ) a
bridged dimer of cyclooctatetraene). The present struc-
ture possesses rigorous C2v symmetry and exhibits
1
readily identified by IR11 and H NMR (comparison to
authentic sample). Aromatization of cyclohexadiene
requires the loss of H2. However, gas chromatographic/
mass spectrometric analysis of the soluble residue from
these reactions revealed no evidence of cyclohexene.
Hence, it does not appear that cyclohexadiene functions
as a hydrogen scavenger. Cyclopentadiene reacted with
[Mn(CO)5OClO3] to produce a moderate amount of the
cyclopentadienyl product, [(η5-C5H5)Mn(CO)3], which
1
was also identified by IR and H NMR. On the other
hand, other conjugated dienes (including 1,3-cycloocta-
diene, isoprene, and 2,3-dimethyl-1,3-butadiene) were
found to be essentially unreactive, affording the recovery
of [Mn(CO)5OClO3] (35-60%).
(11) Kane-Maguire, L. A. P.; Sweigart, D. A. Inorg. Chem. 1979, 18,
700.
(12) Reimann, H.; Singleton, E. J . Chem. Soc., Dalton Trans. 1974,
808.
(13) (a) See reference 7. (b) Verona, I.; Gutheil, J . P.; Pike, R. D.;
Carpenter, G. B. J . Organomet. Chem. 1996, 524, 71.
(14) Dixon, D. T.; Kola, J . C.; Howell, J . A. S. J . Chem. Soc., Dalton
Trans. 1984, 1307.
(15) An X-ray structure was solved for the NBD complex also.
However, increases in standard reflection intensity and cell volume
and a decrease in the extinction coefficient during data collection
suggested that irradiation of the crystal produced an increase in
disorder. Although the solution was of rather poor internal consistency,
the gross structure was akin to that of the 1,5-COD complex.
(16) Wink, D. J . Organometallics 1991, 10, 442.
(17) Wink, D. J .; Wang, N.-F.; Creagan, B. T. Organometallics 1989,
8, 561.
The [(η4-diene)Mn(CO)4]+ products are subject to
nucleophilic displacement of the diene. Over the course
of about an hour in CH3CN, they convert to a product
having carbonyl IR bands at 2133 (vw), 2056 (s), and
2004 (m). The release of NBD from the metal complex
1
was observed by H NMR in CD3CN on the same time
scale. Therefore, it was concluded that the initial
product is the previously unreported complex cis-
[(CH3CN)2Mn(CO)4]+. After several hours this product
converted to fac-[(CH3CN)3Mn(CO)3]+ (IR 2063 (s), 1975
(s, br)).11,12 An IR kinetic study of the initial CH3CN
solvolysis of the NBD complex to the bis-acetonitrile
(18) Wink, D. J .; Oh, C. K. Organometallics 1990, 9, 2403.
(19) Connop, A. H.; Kennedy, R. G.; Knox, S. A. R.; Mills, R. M.;
Riding, G. H.; Woodward, P. J . Chem. Soc., Chem. Commun. 1980,
518.

5588 Organometallics, Vol. 17, No. 25, 1998
Notes
Ta ble 3. Atom ic Coor d in a tes a n d Equ iva len t
Ta ble 2. Cr ysta l Da ta a n d Str u ctu r e Refin em en t
for [(η4-1,5-Cycloocta d ien e)Mn (CO)4]ClO4
Isotr op ic Disp la cem en t P a r a m eter s for
[(η4-1,5-Cycloocta d ien e)Mn (CO)4]ClO4
A. Crystal Data
x
y
z
U(eq),a
Å
empirical formula
fw
C12H12ClMnO8
374.61
Mn(1)
C(1)
C(2)
C(3)
C(4)
C(9)
C(10)
O(1)
O(2)
O(5)
O(6)
Cl(1)
0
3093(1)
1671(3)
1689(3)
844(4)
2500
38(1)
51(1)
48(1)
64(1)
72(1)
49(1)
55(1)
74(1)
80(1)
94(1)
84(1)
56(1)
cryst size, mm
cryst syst
lattice params, Å
0.56 × 0.58 × 0.64
orthorhombic
a ) 11.063(2)
b ) 11.9283(13)
c ) 10.883(2)
1436.1(4)
Pbcn
252(3)
1265(3)
1547(4)
712(4)
1064(3)
1779(3)
2766(4)
3824(4)
1466(3)
1489(3)
847(3)
860(3)
1589(3)
3082(3)
2500
779(4)
-1340(4)
3229(3)
4121(4)
3372(3)
4708(3)
6614(3)
7995(3)
7303(1)
volume, Å3
748(4)
space group
Z
-2138(2)
1252(3)
-562(4)
-886(3)
0
4
density (calcd), mg m-3
abs coeff, mm-1
1.733
1.143
B. Intensity Measurements
a
temp, K
scan type
F000
298(2)
ω
760
U(eq) is defined as one-third of the trace of the orthogonalized
Uij tensor.
θ range for data
collection, deg
index ranges
2.51-26.00
Ta ble 4. Selected Bon d Len gth s (Å) a n d An gles
(d eg) for [(η4-1,5-Cycloocta d ien e)Mn (CO)4]ClO4
-1 e h e 13, -1 e k e 14,
-1 e l e 13
1899
1415 (Rint ) 0.0585)
empirical
Mn(1)-C(10)
Mn(1)-C(2)
C(1)-C(2)
1.844(4)
2.319(4)
1.364(5)
1.479(5)
1.126(4)
1.430(3)
Mn(1)-C(9)
Mn(1)-C(1)
C(2)-C(3)
C(9)-O(1)
Cl(1)-O(6)
1.868(4)
2.323(4)
1.505(6)
1.124(4)
1.430(4)
reflns collected
independent reflns
abs corr
C(3)-C(4)
C(10)-O(2)
Cl(1)-O(5)
max. and min. transmission
0.405, 0.359
C. Structure Solution and Refinement
refinement method
full-matrix least-squares on F2
C(10)-Mn(1)-C(9)
C(9)-Mn(1)-C(2)
C(9)-Mn(1)-C(1)
C(2)-C(1)-Mn(1)
C(1)-C(2)-Mn(1)
C(4)-C(3)-C(2)
86.5(2) C(10)-Mn(1)-C(2)
109.7(2) C(10)-Mn(1)-C(1)
75.7(2) C(2)-Mn(1)-C(1)
72.8(2) C(1)-C(2)-C(3)
73.1(2) C(3)-C(2)-Mn(1)
117.5(3) O(1)-C(9)-Mn(1)
90.4(2)
91.7(2)
no. of data, restraints, params 1415, 0, 102
goodness of fit of F2
final R indices [I > 2σ(I)]
R indices (all data)
extinction coeff
0.895
34.18(13)
124.5(4)
111.5(2)
176.3(4)
109.9(2)
R1 ) 0.0462, wR2 ) 0.1208
R1 ) 0.0724, wR2 ) 0.1325
0.022(2)
O(2)-C(10)-Mn(1) 176.3(4) O(6)-Cl(1)-O(5)
largest peak and hole
0.799, -0.311
in diff map, e Å-3
a
Only independent bond lengths and angles listed; see Experi-
mental Section.
nearly perfect octahedral ligand arrangement around
the metal. The carbonyls are staggered with respect to
the ring. The manganese atom lies 1.685 Å above the
center of the plane produced by the four vinyl carbons.
The carbonyls that are situated trans to another car-
bonyl are slightly longer than those that are oriented
trans to an olefinic bond.
Wink has shown that conjugated and nonconjugated
dienes have differing donor/acceptor properties.16 The
more accessible LUMO of the former makes them more
effective π-back-bonding ligands. Wink has further
shown that this difference is reflected in the structural
properties of d6 [(η4-diene)ML4]+ complexes. Thus,
while complexes of conjugated dienes show serious dis-
tortions from octahedral ligand arrangement, noncon-
jugated dienes show very little distortion. Although no
manganese structures were available for inclusion in
Wink’s study, [(η4-1,5-COD)Mn(CO)4]+ fits the estab-
lished pattern very well. It seems likely that the mini-
mal ability of the electron-deficient [Mn(CO)4]+ frag-
ment to donate electron density to the low-lying LUMO
of the conjugated dienes underlies the observed instabil-
ity of these complexes found in the present study.
Several [(η6-triene)Mn(CO)3]ClO4 species were syn-
thesized from [Mn(CO)5OClO3]. The yields are shown
in Table 5. Satisfactory results were anticipated for
these reactions since the AgClO4 abstraction of halide
from [Mn(CO)5X] is known to allow coordination of
aromatic ligands.2,9 The reactions were typically clean,
as judged by IR, requiring several hours at reflux in
CH2Cl2. Yellow, crystalline products either precipitated
during the course of the reaction or were precipitated
upon the addition of ether.
F igu r e 1. Thermal ellipsoid drawing of [(η4-1,5-cycloocta-
diene)Mn(CO)4]ClO4 at the 50% probability level.
Ta ble 5. Syn th esis Resu lts for
[(η6-Tr ien e)Mn (CO)3]ClO4 Com p lexes
preparation yield,
IR (νCO,
CH3NO2)
arene
time, h
%
1,3,5-trimethoxybenzene
1,2,4,5-tetramethylbenzene
dibenzopyrrole (carbazole)
cycloheptatriene
4.5
3.0
4.0
2.0
85
60
83
66
2069, 2004
2069, 2010
2067, 2007
2078, 2022
We have also attempted to form the complexes [(η2-
olefin)Mn(CO)5]ClO4 (olefin ) cyclopentene, 1-pentene,
norbornylene, cis-stilbene, phenylacetylene, and 3-hex-
yne). Upon stirring the perchlorate complex and the
olefin together in various ratios in CH2Cl2 at room tem-
perature or reflux, new carbonyl IR bands are observed.
These bands (2162 (vw), 2117 (vw), 2078 (s), 2042 (w))
suggest the formation of electron-deficient pentacarbo-
nyl species. The spectra appear to be in agreement with
those of previously reported ethylene and propylene

Notes
Organometallics, Vol. 17, No. 25, 1998 5589
were obtained using 1,3-cyclohexadiene (66% yield). 1H NMR
complexes.4 However, [Mn(CO)5OClO3] was invariably
recovered from these reactions. If, in fact, the olefin
complexes are being formed, it would seem that the per-
chlorate ligand is competing with the olefins for coor-
dination to the strongly electrophilic [Mn(CO)5]+ frag-
ment.
In summary, we have demonstrated a one-step, high-
yield synthesis of the useful Mn(I) carbonyl complex
[Mn(CO)5OClO3]. This species has demonstrated be-
havior consistent with facile release of the 16-electron
[Mn(CO)5]+, which coordinates sufficiently electron-rich
polyene ligands with the loss of the appropriate number
of carbonyl ligands.
(CD3COCD3): δ 6.94 (s, 6 H). IR (νCO, CH3NO2): 2082 (s), 2027
(s, br) cm-1
.
P r ep a r a tion of [(η5-Cyclop en ta d ien yl)Mn (CO)3] fr om
Cyclop en ta d ien e. [Mn(CO)5OClO3] (0.119 g, 0.404 mmol)
and cyclopentadiene (0.0515 g, 0.779 mmol) were refluxed in
50 mL of CH2Cl2 under N2 in the dark for 16.5 h. A black,
insoluble precipitate was removed via filtration. The filtrate
was evaporated and chromatographed on alumina with diethyl
ether. After solvent evaporation, the orange oil was dried un-
der vacuum (0.0206 g, 0.101 mmol, 25%). 1H NMR (CDCl3):
δ 4.76 (s, 5 H). IR (νCO, CH2Cl2): 2022 (s), 1932 (s, br) cm-1
.
P r ep a r a t ion of [(η6-Dib en zop yr r ole)Mn (CO)3]ClO4.
[Mn(CO)5OClO3] (0.150 g, 0.509 mmol) and dibenzopyrrole
(carbazole, 0.259 g, 1.55 mmol) were refluxed in 20 mL of
CH2Cl2 under N2 for 4 h. The mixture was concentrated under
vacuum and precipitated by the addition of diethyl ether. The
pale yellow product was washed with diethyl ether and dried
under vacuum (0.172 g, 0.425 mmol, 83%). Found: C, 44.25;
H, 2.24; N, 3.45. Calcd for C15H8ClMnNO7: C, 44.53; H, 1.99;
N, 3.46. 1H NMR (CD3COCD3): δ 6.43 (t, J ) 6.4, 1 H), 6.97
(t, J ) 6.6, 1 H), 7.44 (d, J ) 7.0, 1 H), 7.55 (t, J ) 7.3, 1 H),
7.85 (m, 2 H), 8.24 (d, J ) 6.6, 1 H), 8.51 (d, J ) 7.9 1 H). 13C
NMR (CD3COCD3): δ 84.6, 88.4, 95.6, 99.8, 111.6, 119.6, 120.8,
121.6, 123.8, 140.7, 145.1. Similar results were obtained using
other arenes.
Exp er im en ta l Section
Gen er a l Meth od s. Infrared spectra were recorded on a
Perkin-Elmer 1600 FTIR using a liquid cell with CaF2 win-
1
dows, and H NMR (300 MHz) and 13C NMR (75 MHz) spectra
were collected using a General Electric QE-300 spectrometer.
Microanalyses were carried out by Atlantic Microlaboratories,
Norcross, GA.
Ma ter ia ls. All solvents were dried and purified according
to standard methods. Dienes were purchased from Aldrich
and distilled from CaH2 prior to use. Trifluoroacetic anhydride
(TFAA) was purchased from Aldrich and used as received.
P r ep a r a tion of [Mn (CO)5OClO3]. TFAA (15 mL) was
cooled to 0 °C, and [Mn2(CO)10] (1.50 g, 3.85 mmol) was added.
The suspension developed a brown color. Aqueous HClO4 (3
mL, 60% solution) was then added dropwise. During 1.5 h
stirring at 0 °C, the mixture became a clear, orange solution.
The TFAA was removed under vacuum, and the resulting
yellow slurry was dried over MgSO4. Boiling CH2Cl2 (10 mL)
was then added, and the suspension was hot-filtered. The
yellow, crystalline product was precipitated by the addition
of diethyl ether and dried under vacuum (2.12 g, 7.20 mmol,
Attem p ted P r ep a r a tion of Con ju ga ted [(η4-Dien e)Mn -
(CO)4]ClO4 a n d [(η2-Olefin )Mn (CO)5]ClO4 Com p lexes.
[Mn(CO)5OClO3] and conjugated diene or olefin (2.0-3.0 equiv)
were refluxed in CH2Cl2. Reaction progress was monitored
by IR. Cationic products were precipitated using diethyl ether.
Solvolysis Kin etics of [(η4-Nor bor n a d ien e)Mn (CO)4]-
ClO4. Solvolysis reactions were carried out under pseudo-first-
order conditions by dissolving the NBD complex (5.09 mM)
into a solution of CH3CN in CH3NO2, which was preequili-
brated to and maintained at 25.0 ( 0.2 °C in a Fisher Isotemp
model 910 thermostatic bath. Samples were periodically
withdrawn and immediately examined by IR spectroscopy. The
loss of the diene ligand was measured by the decrease in the
94%). IR (νCO, CH2Cl2): 2157 (vw), 2074 (s), 2023 (w) cm-1
.
The reaction has been carried out on a larger scale: 3.00 g of
[Mn2(CO)10], 20 mL of TFAA, 4 mL of HClO4 solution. It is
especially important when using a larger scale that the HClO4
be added slowly to avoid a large exotherm. The triflate
complex is prepared in a similar fashion, except that removal
of water with MgSO4 is unnecessary and recrystallization is
carried out from a small volume of diethyl ether.
absorbance of the IR band at 2118 cm-1
.
X-r a y Diffr a ction Stu d y of [(η4-1,5-Cycloocta d ien e)Mn -
(CO)4]ClO4. Suitable crystals were grown by diffusion of
diethyl ether into a nitromethane solution of the compound
at 25 °C. One of the mostly transparent yellow block-shaped
crystals was cut and glued to a glass fiber. X-ray data
collection was carried out at 25 °C using a Siemens P4 single-
crystal diffractometer (Mo KR radiation, 0.710 73 D) controlled
by XSCANS version 2.1 software.20 Omega scans were used
P r epar ation of [(η4-Nor bor n adien e)Mn (CO)4]ClO4. [Mn-
(CO)5OClO3] (2.50 g, 8.49 mmol) and NBD (ca. 2 mL) were
dissolved in 100 mL of CH2Cl2 and refluxed under N2 for 5 h.
A bright yellow, crystalline precipitate slowly formed. The
mixture was cooled and the precipitate collected, washed with
diethyl ether, and dried under vacuum (2.86 g, 7.99 mmol,
94%). Anal. Found: C, 36.93; H, 2.21. Calcd for C11H8-
ClMnO8: C, 36.85; H, 2.25. 1H NMR (CD3NO2): δ 1.80 (bs, 2
H, CH2), 4.13 (bs, 2 H, CHbridgehead), 5.79 (bs, 4 H, CHvinyl). 13C
NMR (CD3NO2): δ 49.0, 67.8, 85.9, 208.6 (MCO), 215.7 (MCO).
for data collection, at variable speeds from 10 to 60 deg min-1
.
Three standard reflections were measured after every 97
reflections; they showed an 8.4% decrease in intensity over
the course of the data collection, and corrections were made
for their variation. Data reduction included profile fitting and
an empirical absorption correction based on 406 ψ-scan reflec-
tions. In the initial refinement, a small correction was made
for the presence of extinction.
IR (νCO, CH3NO2): 2118 (m), 2067 (sh), 2046 (s) cm-1
.
The structure was determined by direct methods and refined
initially by use of programs in the SHELXTL 5.1 package,21
which were also used for all figures. Both the cation and the
P r ep a r a tion of [(η4-1,5-Cycloocta d ien e)Mn (CO)4]ClO4.
This complex was prepared by a method similar to that of the
norbornadiene complex (20 h reflux, 55% yield). 1H NMR (CD3-
NO2): δ 2.47 (d, J ) 9.2 Hz, 4 H, CH2exo), 3.00 (bd, J ) 11.4,
4 H, CH2endo), 5.20 (bs, 4 H, CHvinyl). 13C NMR (CD3NO2): δ
30.0, 104.6, 209.4 (MCO), 216.3 (MCO). IR (νCO, CH3NO2):
1
anion lie on a 2-fold axis along 0, y, /4, so only half of each is
independent. All six independent hydrogen atoms appeared
in a difference map, and each was introduced in an ideal
position, riding on the atom to which it is bonded. Each was
refined with isotropic temperature factors 20% greater than
that of the ridden atom. All other atoms were refined with
2113 (m), 2060 (sh), 2038 (s) cm-1
.
P r ep a r a tion of [(η6-Ben zen e)Mn (CO)3]ClO4 fr om Cy-
cloh exa d ien es. [Mn(CO)5OClO3] (0.135 g, 0.458 mmol) and
1,4-cyclohexadiene (0.131 g, 1.63 mmol) were refluxed in 50
mL of CH2Cl2 under N2 in the dark for 20 h. A pale yellow
precipitate slowly formed. The mixture was cooled and the
precipitate collected, washed with diethyl ether, and dried
under vacuum (0.114 g, 0.361 mmol, 79%). Similar results
(20) XSCANS, X-ray Single-Crystal Analysis System; Siemens
Analytical X-ray Instruments Inc.: Madison, WI, 1993.
(21) Sheldrick, G. M. SHELXTL/ PC, Integrated System for Data
Collection, Processing, Structure Solution and Refinement; Siemens
Analytical X-ray Instruments Inc.: Madison, WI, 1990.

5590 Organometallics, Vol. 17, No. 25, 1998
Notes
anisotropic thermal parameters. Final refinement on F2 was
from an instrument grant from the National Science
Foundation (CHE-8206423) and a grant from the Na-
tional Institutes of Health (RR-06462).
carried out using SHELXL 93.22
Ack n ow led gm en t is made to the Thomas F. and
Kate Miller J effress Memorial Trust and to the College
of William and Mary for support of this research. The
X-ray equipment was purchased with the assistance
Su p p or tin g In for m a tion Ava ila ble: Crystallographic
data: tables of bond lengths and angles, anisotropic displace-
ment parameters, hydrogen fractional coordinates, and se-
lected torsion angles (4 pages). Ordering information is given
on any current masthead page.
(22) Sheldrick, G. M. SHELXL 93, Program for the Refinement of
Crystal Structures; University of Go¨ttingen, Germany, 1993.
OM9805739