Reactivity of the amido complex [Re(NHpTol)(Co)3(bipy)] toward neutral organic electrophiles

Article abstract of DOI:10.1021/om020667p

The amido complex [Re(NHpTol)(CO)₃(bipy)] (1) reacts with pTolNCS and with Ph₂CCO giving the products of the insertion of these heterocumulenes into the Re-N and N-H bonds, the complexes [Re{SC(NpTol)(NHpTol)}(CO)₃(bipy)]

Full text of DOI:10.1021/om020667p

Organometallics 2003, 22, 257-263
257
Rea ctivity of th e Am id o Com p lex
[Re(NHpTol)(CO)3(bip y)] tow a r d Neu tr a l Or ga n ic
Electr op h iles
Eva Hevia, J ulio Pe´rez,* and V´ıctor Riera
Departamento de Quı´mica Orga´nica e Inorga´nica / IUQOEM, Facultad de Quı´mica,
Universidad de Oviedo-CSIC, 33071 Oviedo, Spain
Daniel Miguel
Departamento de Quı´mica Inorga´nica, Facultad de Ciencias, Universidad de Valladolid,
47071 Valladolid, Spain
Received August 15, 2002
The amido complex [Re(NHpTol)(CO)3(bipy)] (1) reacts with pTolNCS and with Ph2CCO
giving the products of the insertion of these heterocumulenes into the Re-N and N-H bonds,
the complexes [Re{SC(NpTol)(NHpTol)}(CO)3(bipy)] (2) and [Re{N(pTol)C(O)CHPh2}(CO)3-
(bipy)] (3), respectively. The reaction of 1 with activated acetylenes containing at least one
alkoxycarbonyl group afforded the compounds [Re{N(pTol)C(R′)C(R)C(OH)}(CO)3(bipy)] (4a -
c). The formation of the metallacycle present in these compounds involves the activation of
one of the carbonyl ligands of 1. The structures of the complexes 2, 3, and 4b have been
determined by single-crystal X-ray diffraction. 13C NMR and crystallographic data indicate
that the metal-bonded carbon atom of the metallacycle possesses carbene character.
In tr od u ction
that were found to react with the previously known
amido complexes of the group 8-10 metals. Our findings
Low-valent transition metal amido complexes display
a high nucleophilicity at nitrogen as a result of desta-
bilizing interactions between the amido lone electron
pair and filled metal d orbitals.1 As a consequence, these
complexes react with different organic electrophiles,
including unsaturated molecules such as CO2, CS2, and
isocyanates, with formation of C-N bonds. Most of these
studies have been conducted with transition metals of
groups 8-10.2 Bergman reported the synthesis of [Re-
(NHPh)(CO)3(PR3)2] amido complexes and their reactiv-
ity toward CO2.3 We have recently reported the synthe-
sis of [Re(N(R)Ar)(CO)3(bipy)] (R ) H, Me, aryl; bipy )
2,2′-bipyridine) amido complexes4 and their reactivity
with isocyanates.5
are the matter of this paper.
Resu lts a n d Discu ssion
We have previously found (a) that the amido complex
[Re(NHpTol)(CO)3(bipy)] (pTol ) para-tolyl) (1) reacts
with isocyanates5 and (b) that isothiocyanates are less
reactive substrates than isocyanates toward the rhe-
nium methoxo complex [Re(OMe)(CO)3(bipy)].6 There-
fore, we wanted to know whether the amido complex 1
would react with isothiocyanates. While the reactivity
of isocyanates with transition metal organometallic
complexes has been the subject of a number of studies,7
the related isothiocyanate chemistry has been much less
explored.8
We wondered if our rhenium amido complexes can be
used to form C-N bonds with the organic substrates
The reaction of equimolar amounts of 1 and pTolNCS
(see Scheme 1) in THF takes place instantaneously and
is accompanied by a change in the color of the solution
from emerald green to orange. The resulting solution
displayed three ν(CO) bands (the one at higher fre-
quency being much more acute than the other two) in
the IR spectrum, indicative of the retention of a fac-
tricarbonyl moiety. Their frequencies were some 15 cm-1
higher than those of the precursor amido complex, as
expected for the addition of an electrophile. The 1H NMR
* Correspondence author. E-mail: japm@sauron.quimica.uniovi.es.
(1) (a) Mayer, J . M. Comments Inorg. Chem. 1988, 8, 125. (b)
Caulton, K. G. New J . Chem. 1994, 18, 25. (c) J ayaprakash, K. N.;
Conner, D.; Gunnoe, T. B. Organometallics 2001, 20, 5254. (d) Conner,
D.; J ayaprakash, K. N.; Gunnoe, T. B.; Boyle, P. D. Inorg. Chem. 2002,
41, 3042. (e) Fulton, J . R.; Holland, A. W.; Fox, D. J .; Bergman, R. G.
Acc. Chem. Res. 2002, 35, 44.
(2) (a) Cowan, R. L.; Trogler, W. C. J . Am. Chem. Soc. 1989, 111,
4750. (b) Hartwig, J . F.; Bergman, R. G.; Andersen, R. A. J . Am. Chem.
Soc. 1991, 113, 6499. (c) Glueck, D. J .; Newman Winslow, L. J .;
Bergman, R. G. Organometallics 1991, 10, 1462. (d) Villanueva, L. A.;
Abboud, K. A.; Boncella, J . M. Organometallics 1992, 11, 2963. (e)
Legzdins, P.; Rettig, S. J .; Ross, K. J . Organometallics 1994, 13, 569.
(f) Boncella, J . M.; Villanueva, L. A. J . Organomet. Chem. 1994, 465,
297. (g) Vanderlende, D. D.; Abboud, K. A. Boncella, J . M. Inorg. Chem.
1995, 34, 5319. (h) Boncella, J . M.; Eve, T. M.; Rickman, B.; Abboud,
K. A. Polyhedron 1998, 5, 725.
(6) Hevia, E.; Pe´rez, J .; Riera, L.; Riera, V.; Miguel, D.; del R´ıo, I.;
Garc´ıa-Granda, S. Chem., Eur. J . 2002, 8, 4510.
(7) For a review of transition metal mediated reactions of isocyan-
ates, see: Braunstein, P.; Nobel, D. Chem. Rev. 1989, 89, 1927. See
also refs 2b, c, e, f, and g.
(8) The reactivity of lanthanocene diphenylamido complexes toward
PhNCS has been recently reported: Li, H.; Yao, Y.; Shen, Q.; Weng,
L. Organometallics 2002, 21, 2529.
(3) Simpson, R. D.; Bergman, R. G. Organometallics 1993, 12, 781.
(4) Hevia, E.; Pe´rez, J .; Riera, V.; Miguel, D. Organometallics 2002,
21, 1966.
(5) Hevia, E.; Pe´rez, J .; Riera, V.; Miguel, D. Chem. Commun. 2002,
1814.
10.1021/om020667p CCC: $25.00 © 2003 American Chemical Society
Publication on Web 12/17/2002

258 Organometallics, Vol. 22, No. 2, 2003
Hevia et al.
Ta ble 1. Selected Bon d Dista n ces a n d An gles for
Com p lex 2
Bond Distances (Å)
Re(1)-C(1)
Re(1)-C(2)
Re(1)-C(3)
Re(1)-N(1)
Re(1)-N(2)
1.872(11)
1.888(11)
1.898(9)
2.180(6)
2.156(7)
Re(1)-S(1)
S(1)-C(4)
C(4)-N(3)
C(4)-N(4)
2.498(2)
1.755(8)
1.302(9)
1.359(10)
Bond Angles (deg)
C(1)-Re(1)-C(2)
C(3)-Re(1)-C(2)
C(1)-Re(1)-C(3)
C(2)-Re(1)-N(1)
C(1)-Re(1)-N(1)
C(3)-Re(1)-N(1)
C(2)-Re(1)-N(2)
C(3)-Re(1)-N(2)
N(1)-Re(1)-N(2)
87.4(3)
89.8(4)
88.6(4)
173.8(3)
92.2(3)
96.3(3)
99.6(3)
170.5(3)
74.2(3)
C(1)-Re(1)-N(2)
C(2)-Re(1)-S(1)
C(1)-Re(1)-S(1)
C(3)-Re(1)-S(1)
N(1)-Re(1)-S(1)
N(2)-Re(1)-S(1)
C(4)-S(1)-Re(1)
C(4)-N(4)-C(41)
C(4)-N(3)-C(51)
92.6(3)
96.8(2)
173.7(3)
96.0(3)
83.11(17)
82.94(14)
116.1(3)
133.1(8)
119.2(7)
Sch em e 2
F igu r e 1. Plot of [Re{SC(NpTol)(NHpTol)}(CO)3(bipy)] (2)
showing the atom-numbering scheme (30% probability
ellipsoids).
Sch em e 1
the Re-N bond of the amido complex 1. The Re-S
distance, 2.498(2) Å, is close to those found for the
complexes [Re{SC(dNEt)OMe}(CO)3(bipy)] (2.5131(14)
Å) and [Re{SC(dS)OMe}(CO)3(bipy)] (2.5059(15) Å),
obtained by the reactions of [Re(OMe)(CO)3(bipy)] with
EtNCS and with CS2 respectively.6 The S-C distance
in 2, 1.755(8) Å, also close to those found in the above
complexes (1.729(6) and 1.755(5) Å respectively), is
within the range of single C-S bonds.9 The distances
C(4)-N(3) (1.302(9) Å) and C(4)-N(4) (1.359(10) Å) are
intermediate between single and double bonds, indicat-
ing some degree of delocalization. In view of the
structure, the equivalence of the two para-tolyl groups
in the NMR spectrum can be ascribed to the fast
exchange of the hydrogen atom between the two nitro-
gens.
spectrum of the crude product showed the presence of
a single species 2 with four bipy signals, indicating the
presence of a mirror plane. This was confirmed by the
five bipy signals in the 13C NMR spectrum. Both spectra
contained only one set of para-tolyl signals, although
their integration against the signals of the bipy ligand
1
in the H NMR spectrum indicated the existence of two
para-tolyl groups, as expected for the addition of a
pTolNCS molecule to the p-tolylamido complex. Thus,
the two para-tolyl groups are equivalent. A broad signal
at 2.16 ppm in 1H NMR is assigned to the nitrogen-
bonded hydrogen atom. The limited solubility of 2
precluded the observation of more signals than those
of bipy and p-tolyl groups in the 13C NMR.
We have previously studied the reactivity of the amido
complex 1 with isocyanates.5 Our observations, as well
as those of previous workers,2f,g can be accounted for
assuming initial nucleophilic attack by the undissoci-
ated amido ligand to the central carbon of the isocyanate
and rearrangement of the resulting zwitterionic species
through a displacement of the amino end of the resulting
ligand by the better donor amido end (see Scheme 2).
Then, for R ) H, H and {Re(CO)3(bipy)} would exchange
sites due to the different acidity of the two nitrogens.
For isothiocyanate insertion, the putative zwitterionic
Complex 2 was isolated as an analytically and spec-
troscopically pure solid by crystallization of the crude
product in 81% yield (see Experimental Section).
The structure of 2 was determined by means of X-ray
diffraction on a single crystal of 2‚CH2Cl2 obtained by
slow diffusion of diethyl ether into a CH2Cl2 solution of
the complex. A representation of the molecular structure
of 2 is shown in Figure 1, and selected distances and
angles are given in Table 1.
The molecule of 2 consists of a {Re(CO)3(bipy)}
fragment bonded to the sulfur atom of a SC(NpTol)-
(N(H)pTol) thioureato ligand resulting from the formal
insertion of the C-S bond of p-tolylisothiocyanate into
(9) Carmona, E.; Contreras, L.; Sa´nchez, L. J .; Gutie´rrez-Puebla,
E.; Monge, A. J . Chem. Soc., Dalton Trans. 1989, 2003.

Amido Complex [Re(NHpTol)(CO)3(bipy)]
Organometallics, Vol. 22, No. 2, 2003 259
Ta ble 2. Selected Bon d Dista n ces a n d An gles for
Com p lex 3
Bond Distances (Å)
Re(1)-C(1)
Re(1)-C(2)
Re(1)-C(3)
Re(1)-N(1)
Re(1)-N(2)
1.889(10)
1.880(10)
1.907(10)
2.172(6)
2.192(6)
Re(1)-N(3)
N(3)-C(4)
N(3)-C(31)
C(4)-O(4)
2.184(6)
1.333(8)
1.432(9)
1.228(8)
Bond Angles (deg)
C(2)-Re(1)-C(1)
C(2)-Re(1)-C(3)
C(1)-Re(1)-C(3)
C(2)-Re(1)-N(1)
C(1)-Re(1)-N(1)
C(3)-Re(1)-N(1)
C(2)-Re(1)-N(2)
C(3)-Re(1)-N(2)
N(1)-Re(1)-N(2)
88.4(4)
87.0(3)
88.8(3)
100.3(3)
92.2(3)
172.6(3)
174.1(3)
98.7(3)
73.9(2)
C(1)-Re(1)-N(2)
C(2)-Re(1)-N(3)
C(1)-Re(1)-N(3)
C(3)-Re(1)-N(3)
N(1)-Re(1)-N(3)
N(3)-Re(1)-N(2)
C(4)-N(3)-Re(1)
C(4)-N(3)-C(31)
C(31)-N(3)-Re(1)
93.2(3)
94.3(3)
175.7(3)
94.7(3)
84.0(2)
83.7(2)
122.6(5)
120.6(6)
116.6(5)
C-H unit of the diphenylmethyl group appears as
1
signals at 54.99 and 4.58 ppm in the 13C and H NMR
F igu r e 2. Plot of [Re{N(pTol)C(O)CHPh2}(CO)3(bipy)] (3)
showing the atom-numbering scheme (30% probability
ellipsoids).
spectra, respectively, and the carbonyl group within the
amidato ligand resonates at 174.29 in 13C NMR.
The amidato ligand present in 3 corresponds to a
formal insertion of the CdC bond of the ketene into the
amido N-H bond of complex 1. A similar insertion of
diphenylketene was reported by Boncella for a square-
planar nickel(II) anilido complex.2g The reaction re-
sembles those of secondary amines with ketenes to give
N,N-disubstituted amides.10 The different regiochem-
istry (insertion into N-H versus Re-N) encountered for
the formation of 3 with respect to that of 2 can be
rationalized assuming proton transfer from the am-
monium nitrogen of the zwitterionic intermediate (re-
sulting from amido attack to the ketene carbonyl carbon)
to the less acidic carbon atom, as depicted in Scheme 3.
Nucleophilic attack by nitrogen at the carbonyl group
is considered to be the first step in the reactions of
amines with ketenes,11 and a zwitterionic species such
as the one depicted in Scheme 3 has been spectroscopi-
cally detected in recent studies of the reaction between
diphenylketene and pyridine.11 The instantaneous reac-
tion of 1 with diphenylketene at room temperature
contrasts with the slower reactions of diphenylketene
with anilines.12 This difference can be rationalized
taking into account that the repulsive interaction
between metal filled d orbitals and the electron pair on
the nitrogen increases the nucleophilicity of the latter.
The molecule of 3 is planar at nitrogen (sum of the
angles around N(3) ) 359.8°), mainly due to the delo-
calization of the amido nitrogen lone pair involving the
carbonyl group. Evidence of this interaction is provided
by the short N(3)-C(4) distance (1.333(8) Å). A similar
feature was found in the complex [Re{N(pTol)C(O)-
NHEt}(CO)3(bipy)], obtained by the reaction of the
amido complex 1 with ethylisocyanate,5 as well as in
the nickel complex mentioned above.2g The N-C(ipso)
distance, 1.462(9), Å is longer than that found in the
anilido complex [Re(NHPh)(CO)3(bipy)] (1.360(5) Å),4
analogous to 1, in which the nitrogen lone pair delocal-
izes through the phenyl group.13 The Re-N(3) distance
Sch em e 3
intermediate would rearrange to the observed S-bound
product. The softer nature of sulfur should be an
important factor of this difference. A similar structural
difference (Re-N versus Re-S) was found for the
reactivity of [Re(OMe)(CO)3(bipy)] with isocyanates and
isothiocyanates.6 A final step of exchange between H
and the metal fragment, like the one in the proposed
mechanism of RNCO insertion,5 does not occur with
isothiocyanate due to the higher acidity of S-H com-
pared with N-H.
The amido complex 1 reacted instantaneously with
diphenylketene, as indicated by a change in the color
of the THF solution from green to orange and a shift to
higher wavenumbers in the IR ν(CO) bands (See Scheme
3). The single product 3 was isolated in a 87% yield and
was characterized by spectroscopy and single-crystal
1
X-ray diffraction. The IR ν(CO) bands and the H NMR
bipy signals are consistent with the presence in solution
of an octahedral molecule with a facial disposition of
the three carbonyl ligands and a mirror plane, as was
found for 2 (see above). In addition, for 3, further
support for this type of structure is lent by the observa-
tion of two signals with an approximate 1:2 intensity
ratio in the carbonyl region of the 13C NMR spectrum.
The results of the structural determination (Figure 2
and Table 2) showed that the molecule of 3 consists of
a {Re(CO)3(bipy)} fragment bonded to the nitrogen atom
of a (N-pTolyl)diphenylacetamidato group. The central
(10) March, J . Advanced Organic Chemistry, 4th ed.; J ohn Wiley
and Sons: New York, 1992; p 799.
(11) Wagner, B. D.; Arnold, B. R.; Brown, G. S.; Lusztyk, J . J . Am.
Chem. Soc. 1998, 120, 1827.
(12) Briody, J . M.; Satchell, D. P. N. Tetrahedron 1966, 22, 2649.
(13) The N-C(ipso) distance in 3 is similar to that found in [Re-
(NH2pTol)(CO)3(bipy)]OTf (1.448(6) Å); see ref 4.

260 Organometallics, Vol. 22, No. 2, 2003
Hevia et al.
Sch em e 4
(2.184(6) Å) is very close to the corresponding Re-N
distance in [Re{N(pTol)C(O)NHEt}(CO)3(bipy)] (2.182-
(4) Å), mentioned above. A consequence of the amido
pair delocalization is that the Re-bonded nitrogen is no
longer nucleophilic; thus, 3 does not further react with
diphenylketene.
F igu r e 3. Plot of [Re{N(pTol)C(CO2Et)C(CO2Et)C(OH)}-
(CO)3(bipy)] (4b) showing the atom-numbering scheme
(30% probability ellipsoids).
Ta ble 3. Selected Bon d Dista n ces a n d An gles for
Com p lex 4b
The amido complex 1 reacted instantaneously with
dimethylacetylenedicarboxylate, DMAD (Scheme 4). As
in the previous reactions of 1 with electrophiles, the
color of the solution changed from green to red. To our
surprise, the IR spectrum of the resulting solution
contained two ν(CO) bands of similar intensity and
width at 1921 and 1852 cm-1. This pattern is diagnostic
of a cis-Re(CO)2 moiety. This was unexpected since fac-
Re(CO)3 fragments are very reluctant to undergo CO
Bond Distances (Å)
Re(1)-C(1)
Re(1)-C(2)
Re(1)-C(3)
Re(1)-N(1)
Re(1)-N(2)
1.869(6)
1.897(6)
2.024(5)
2.200(4)
2.177(4)
Re(1)-N(3)
N(3)-C(11)
C(11)-C(12)
C(12)-C(3)
C(3)-O(3)
2.189(4)
1.304(6)
1.435(6)
1.425(7)
1.354(6)
Bond Angles (deg)
C(1)-Re(1)-C(2)
C(2)-Re(1)-C(3)
C(1)-Re(1)-C(3)
C(2)-Re(1)-N(1)
87.0(2)
91.8(2)
90.8(2)
C(1)-Re(1)-N(3)
C(3)-Re(1)-N(3)
N(3)-Re(1)-N(1)
165.75(18)
75.78(17)
90.06(14)
83.11(15)
1
substitution processes.14 The H NMR of the reaction
96.21(19) N(2)-Re(1)-N(3)
C(1)-Re(1)-N(1) 102.75(19) C(41)-N(3)-Re(1) 123.6(3)
C(3)-Re(1)-N(1) 164.59(17) C(11)-N(3)-C(41) 120.7(4)
C(2)-Re(1)-N(2) 170.03(18) C(11)-N(3)-Re(1) 115.1(3)
crude showed the formation of a single product, 4a ,
which could be isolated in the form of red needle-shaped
1
crystals, whose IR and H NMR were identical to those
C(3)-Re(1)-N(2)
N(2)-Re(1)-N(1)
C(1)-Re(1)-N(2)
C(2)-Re(1)-N(3)
98.04(17) O(3)-C(3)-Re(1)
73.85(15) O(3)-C(3)-C(12)
124.7(4)
116.5(4)
of the crude solutions. The incorporation of DMAD was
indicated by the two CO2Me singlets at 3.66 and 3.37
94.4(2)
97.9(2)
C(12)-C(3)-Re(1) 118.9(3)
1
ppm in the H NMR. Unlike in complexes 2 and 3, an
1
asymmetric bipy pattern was found in the H NMR of
allacycle. The cycle is essentially planar, the major
deviation affecting N(3), 0.0173 Å out of plane. Aside
from the typical small bite angle of the bipy chelate
(N(1)-Re-N(2) ) 73.85(15)°), the main deviations from
an idealized octahedral geometry are imposed by the
metallacycle (for instance, C(3)-Re-N(3) ) 75.78(17)°,
and C(1)-Re-N(3) ) 165.75(18)°). The four atoms that,
in addition to rhenium, form the metallacycle are the
nitrogen from the amido group, the two acetylenic
carbons from EtO2CCtCCO2Et, and one carbon atom
from a carbonyl ligand. The Re-C(3) distance, 2.024(5)
Å, is quite short, suggesting some multiple character.
Thus, for instance, Re-C distances of 2.071(8) and
2.078(10) Å were found for the carbene carbons of the
octahedral LnMdC(OEt)Me and LnMdC(OMe)C(H)d
C(H)Me (LnM ) Re(CO)2(triphos)) complexes,15 and a
Re-C distance of 2.198(8) Å was found for the single
bond in [Re{C(CO2Me)dC(CO2Me)OMe}(CO)3(bipy)].16
4a , indicating the absence of a molecular mirror plane.
As a result, the two carbonyl ligands appeared as two
separate resonances of similar intensity at 205.08 and
199.58 ppm in the 13C NMR spectrum.
A single crystal of 4a suitable to determine its
structure by means of X-ray diffraction could not be
obtained. Therefore, we prepared the analogous complex
4b, resulting from reaction of 1 with diethylacetylene-
dicarboxylate. The spectroscopic data of 4b, given in the
Experimental Section, showed it to be isostructural with
4a . A single crystal of 4b was used for an X-ray
structural determination, the results of which are
displayed in Figure 3 and Table 3.
The molecule of 4b consists of a rhenium atom in a
distorted octahedral environment. Two coordination
positions are occupied by the two carbonyl ligands,
which are in mutual cis disposition (C(1)-Re-C(2) )
87.0(2)°), and two are occupied by the bipy nitrogens.
The remaining two positions belong to the carbon and
nitrogen ends of a five-membered Re-N-C-C-C met-
(15) (a) Bianchini, C.; Marchi, A.; Marvelli, L.; Peruzzini, M.;
Romerosa, A.; Rossi, R. Organometallics 1996, 15, 3804. (b) Bianchini,
C.; Mantovani, N.; Marchi, A.; Marvelli, L.; Masi, D.; Peruzzini, M.;
Rossi, R.; Romerosa, A.; Organometallics 1999, 18, 4501.
(16) Hevia, E.; Pe´rez, J .; Riera, L.; Riera, V.; Miguel, D. Organo-
metallics 2002, 21, 1750.
(14) Koike, K.; Tanabe, J .; Toyama, S.; Tsubaki, H.; Sakamoto, K.;
Westwell, J . R.; J ohnson, F. P. A.; Hori, H.; Saitoh, H.; Ishitani, O.
Inorg. Chem. 2000, 39, 277, and references therein.

Amido Complex [Re(NHpTol)(CO)3(bipy)]
Organometallics, Vol. 22, No. 2, 2003 261
Sch em e 5
insertion into the M-N bond, previously reported by
Boncella,2f-h and with our recently reported insertion
of DMAD into the Re-O bond of alkoxo complexes [Re-
(OR)(CO)3(bipy)] to afford tricarbonyl bipyridine com-
plexes with a Z-alkenyl ligand.16 {Re(CO)3(bipy)} frag-
ments are very robust,20 and a CO activation at these
systems is rare.
In addition to the amido complexes mentioned above,
the recent preparation by Templeton of a five-membered
metallacycle containing a carbene carbon from acetylene
carbons and a carbonyl ligand is pertinent to the present
work.21 Insertion of acetylenes into metal-nitrogen
bonds has few precedents,22 and, recently, such a
reaction allowed Odom to obtain a four-membered
metallacycle in a Mo(IV) complex.23
In agreement with this short distance, the correspond-
ing carbon appears at 269.07 ppm in the 13C NMR, a
chemical shift close to those found for the carbene
complexes mentioned above. Also close are the chemical
shift values reported by Casey for rhenium cyclic
hydroxycarbenes.17
The Re-N(3) distance (2.189(4) Å) is similar to that
found for complex 3, and C-C and C-N distances
within the metallacycle have values between those
expected for single and double bonds, suggesting sig-
nificant delocalization, in agreement with the planarity
of the cycle noted above. The presence of a hydroxy
group is supported by the results of the X-ray structure
determination. Thus, the C(3)-O(3) distance (1.354(6)
Å) corresponds to a single bond,18 and the hydrogen
atom bonded to O(3) was located and refined with the
distance fixed at 0.923 Å, but it was allowed to rotate
freely. Furthermore, the hydrogen resonates at 13.85
ppm in the 1H NMR spectrum, a value similar to
previously reported hydroxycarbenes.17 A hydrogen
bond interaction between this hydrogen and O(16)
(d(O-H) ) 1.684 Å and d(O(3)-O(16)) ) 2.561(7) Å)
completes a six-membered cycle, as represented in
Figure 3 by the dashed line. The two cycles are virtually
coplanar.
In conclusion, we have found that the amido complex
1 reacts with three different organic electrophiles to
form new C-N bonds. The nucleophilicity of 1 is
comparable to those exhibited by previously known
amido compounds of the groups 8-10.
Exp er im en ta l Section
General procedures and preparation of 1 are given else-
where.4
Cr ysta l Str u ctu r e Deter m in a tion for Com p ou n d s 2, 3,
a n d 4b. A suitable crystal was attached to a glass fiber and
transferred to a Bruker AXS SMART 1000 diffractometer with
graphite-monochromatized Mo KR X-radiation and a CCD area
detector. A hemisphere of the reciprocal space was collected
up to 2θ ) 48.6°. Raw frame data were integrated with the
SAINT24 program. The structure was solved by direct methods
with SHELXTL.25 A semiempirical absorption correction was
applied with the program SADABS.26 All non-hydrogen atoms
were refined anisotropically. Hydrogen atoms were set in
calculated positions and refined as riding atoms, with a
common thermal parameter. All calculations and graphics
were made with SHELXTL. Crystal and refinement data are
presented in Table 4.
A reaction like those leading to 4a ,b was observed to
occur between 1 and methyl propiolate (Scheme 4). The
longer reaction time (30 min at room temperature) is
attributed to the lower electrophilic character of the
acetylene.19 Complexes 4a -c were isolated in yields
around 80% (see Experimental Section). No reaction was
observed between 1 and PhCtCCO2Me.
Rea ction of 1 w ith p-Tolylisoth iocya n a te. pTolNCS
(0.013 g, 0.083 mmol) was added to a solution of 1 (0.050 g,
0.083 mmol) in THF (15 mL). The color of the solution changed
instantaneously from green to orange. Solvent was removed
under vacuum, and the red solid was redisolved in CH2Cl2 (5
mL). Slow diffusion of diethyl ether into this solution at room
temperature afforded orange crystals of 2‚CH2Cl2, one of which
was employed for an X-ray structure determination. Yield:
Complex 4a did not react with trimethylphosphine (3
equiv, 4 h, refluxing THF), a fact that indicates that
the opening of the metallacycle is not facile. Treatment
n
of 4a with the stoichiometric amount of either BuLi or
KN(SiMe3)2 led to solutions with lower values of ν(CO)
IR bands, suggesting deprotonation of the OH group.
Addition of methyl triflate afforded the neutral complex
5 (see Scheme 5), spectroscopically characterized (see
Experimental Section).
A rationale for the formation of the metallacycles in
4a -c, depicted in Scheme 4, assumes nucleophilic
amido attack (as discussed for the formation of 2 and
3) to the activated acetylene, attack by the resulting
carbanion to one of the proximal CO groups, and proton
transfer from nitrogen to oxygen.
1
81% (0.051 g). IR (CH2Cl2): 2021, 1919, 1900. H NMR(CD2-
Cl2): 8.85 [m, 2H, bipy], 8.01 [m, 4H, bipy], 7.39 [m, 2H, bipy],
6.91-6.59 [m, 8H, pTol], 2.25 [s, 6H, CH3, pTol], 2.16 [s, 1H,
br, NH]. 13C{1H} NMR (CD2Cl2): 155.48, 153.45 [bipy], 147.65
[pTol], 138.93 [bipy],130.85, 128.91, 128.18 [pTol], 127.33,
123.55 [bipy], 20.84 [CH3, pTol]. Anal. Calcd for C28H23N4O3-
(20) Thus, for instance, CO substitution at these complexes requires
drastic conditions; see ref 14.
(21) Gunnoe, T. B.; Caldarelli, J . L.; White, P. S.; Templeton, J . L.
Angew. Chem., Int. Ed. 1998, 37, 2093.
(22) (a) Kemmitt, R. D. W.; Mason, S.; Moore, M. R.; Fawcett, J .;
Russell, D. R. Chem. Commun. 1990, 1535. (b) Walsh, P. J .; Hollander,
F. J .; Bergman, R. G. J . Organomet. Chem. 1992, 428, 13. (c) Cabeza,
J . A.; del R´ıo, I.; Grepioni, F.; Moreno, M.; Riera, V. Organometallics
2001, 20, 4190.
(23) Katayev, E.; Li, Y.; Odom, A. L. Chem. Commun. 2002, 836.
(24) SAINT+. SAX area detector integration program, Version 6.02;
Bruker AXS, Inc.: Madison, WI, 1999.
The formation of the metallacycles 4a -c contrasts
with the reactivity of DMAD toward ruthenium, nickel,
and palladium amides to give the products of acetylene
(17) Casey, C. P.; Czerwinski, C. J .; Fusie, K. A.; Hayashi, R. K. J .
Am. Chem. Soc. 1997, 119, 3971.
(18) C(16)-O(16) ) 1.234(6) Å and C(13)-O(13) ) 1.199(6) Å
distances are indicative of CdO double bonds.
(25) Sheldrick, G. M. SHELXTL, An integrated system for solving,
refining, and displaying crystal structures from diffraction data,
Version 5.1; Bruker AXS, Inc.: Madison, WI, 1998.
(19) The methoxo complex [Re(OMe)(CO)3(bipy)] reacts with DMAD,
but not with methyl propiolate.
(26) Sheldrick, G. M. SADABS, Empirical Absorption Correction
Program; University of Go¨ttingen: Go¨ttingen, Germany, 1997.

262 Organometallics, Vol. 22, No. 2, 2003
Ta ble 4. Cr ysta l Da ta a n d Refin em en t Deta ils for Com p lexes 2, 3, a n d 4b
Hevia et al.
2
3
4b
formula
fw
C
28H23N4O3ReS‚CH2Cl2
C
38H34N3O5Re
C32H34N3O8Re
774.78
766.69
798.88
cryst syst
space group
a, Å
b, Å
c, Å
monoclinic
P21/c
15.275(3)
17.059(3)
12.377(2)
90
109.805(4)
90
3034.2(9)
4
triclinic
P1h
triclinic
P1h
8.7734(17)
11.721(2)
16.512(3)
101.297(4)
90.510(4)
99.202(4)
1642.2(6)
2
8.895(2)
13.262(3)
15.644(4)
65.453(4)
81.655(4)
80.031(4)
1647.8(7)
2
R, deg
â, deg
γ, deg
V, Å3
Z
T, K
295(2)
1.678
1504
293(2)
1.616
796
293(2)
1.562
772
Dc, g cm-3
F(000)
λ(Mo KR), Å
cryst size, mm
µ, mm-1
scan range, deg
no. of reflns measd
no. of ind reflns
no. of data/restraints/params
goodness-of-fit on F2
R1/Rw2 [I>2σ(I)]
R1/Rw2 (all data)
0.71073
0.03 × 0.10 × 0.11
5.209
1.11 e θ e 23.26
13 402
4357
4357/0/367
0.929
0.0389/0.0546
0.0755/0.0591
0.71073
0.04 × 0.08 × 0.19
3.749
1.26 e θ e 23.32
10 760
4725
4725/0/425
1.004
0.0324/0.0657
0.0464/0.0875
0.71073
0.04 × 0.07 × 0.25
3.739
1.70 e θ e 23.45
10 588
4774
4774/0/379
1.020
0.0282/0.0637
0.0341/0.0652
ReS‚CH2Cl2: C, 45.43; H, 3.28; N, 7.30. Found: C, 45.55; H,
3.31; N, 7.43.
for an X-ray experiment. Yield: 0.046 g, 79%. IR (THF): 1920,
1851. 1H NMR(CD2Cl2): 13.85 [s, br, 1H, OH], 8.89 [m, 1H,
bipy], 8.50 [m, 1H, bipy], 7.96 [m, 2H, bipy], 7.60 [m, 3H, bipy],
7.46 [m, 1H, bipy], 6.48 [m, 4H, pTol], 4.16 [q (6.98 Hz), 2H,
OCH2CH3], 3.82 [q (6.98 Hz), 2H, OCH2CH3], 2.07 [s, 3H, CH3,
pTol], 1.81 [t (6.98 Hz), 3H, OCH2CH3], 1.20 [t (6.98 Hz), 3H,
OCH2CH3]. 13C{1H} NMR (CD2Cl2): 269.07 [RedC], 205.45
[CO], 199.84 [CO], 171.90 [CdO], 168.12 [NCdC], 165.06 [Cd
O], 156.68, 154.13, 153.73, 152.34 [bipy], 143.11 [C(OH)C(CO2-
Me)], 138.32, 135.79 [bipy], 134.87, 129.21 [pTol], 126.94,
126.46 [bipy], 123.21 [pTol], 122.60, 122.44 [bipy], 113.44
[pTol], 61.20 [OCH2CH3], 59.9 [OCH2CH3], 25.94 [CH3, pTol],
14.36 [OCH2CH3], 13.74 [OCH2CH3]. Anal. Calcd for C24H20N3O5-
Re: C, 47.85; H, 3.72; N, 5.97. Found: C, 47.90; H, 3.75; N,
5.84.
Rea ction of 1 w ith Dip h en ylk eten e. Ph2CdCdO27 (13
µL, 0.083 mmol) was added to a solution of 1 (0.050 g, 0.083
mmol) in THF (15 mL). The color of the solution changed
instantaneously from green to orange. Slow diffusion of hexane
into this solution at room temperature afforded orange crystals
of 3‚THF, one of which was employed for an X-ray structure
determination. Yield: 87% (0.057 g). IR (THF): 2014, 1914,
1887. 1H NMR(CD2Cl2): 8.86 [m, 2H, bipy], 8.04 [m, 4H, bipy],
7.34 [m, 2H, bipy], 7.05 [m, 6H, Ph], 6.73 [m, 4H, Ph], 6.63,
6.59, 5.93, 5.91 [AA′BB′, 4H, pTol], 4.58 [s, 1H, CH], 2.18 [s,
3H, CH3, pTol]. 13C{1H} NMR (CD2Cl2): 199.39 [2CO], 193.68
[CO], 174.29 [OdC], 155.66, 155.08 [bipy], 149.10, [pTol],
143.32 [Ph], 139.46 [bipy], 133.04 [pTol], 129.31 [Ph], 128.97
[bipy], 127.97 [Ph], 126.90, 126.52, 125.99 [Ph, pTol], 122.60
[bipy], 54.99 [CH], 20.80 [CH3, pTol]. Anal. Calcd for C38H34N3O5-
Re: C, 57.13; H, 4.28; N, 5.25. Found: C, 57.18; H, 4.19; N,
5.33.
Rea ction of 1 w ith Meth yl P r op iola te. HCtCCO2Me
(7.5 µL, 0.083 mmol) was added to a solution of 1 (0.050 g,
0.083 mmol) in THF (10 mL). After 30 min stirring, the solvent
was removed under vacuum and the red solid was redissolved
in CH2Cl2 (10 mL). Slow diffusion of hexanes into this solution
at room temperature afforded red crystals of 4c. Yield: 0.041
g, 81%. IR (THF): 1918, 1848. 1H NMR (CD2Cl2): 13.60 [s,
br, 1H, OH], 9.13 [m, 1H, bipy], 8.37 [m, 1H, bipy], 7.88 [m,
2H, bipy], 7.63 [m, 3H, bipy], 7.27 [m, 1H, bipy], 6.60, 6.56,
5.98, 5.94 [AA′BB′, 4H, pTol], 3.70 [s, 3H, OCH3], 2.10 [s, 3H,
CH3, pTol]. 13C{1H} NMR (CD2Cl2): 269.34 [RedC], 204.93
[CO], 200.21 [CO], 169.78 [NCHdC], 169.07, 165.01 [CdO],
156.37, 154.20, 153.94, 151.83 [bipy], 146.74 [C(OH)C(CO2-
Me)], 139.75, 138.02 [bipy], 134.36, 129.03 [pTol], 126.83,
126.61 [bipy], 122.55 [pTol], 122.49, 122.11 [bipy], 115.77
[pTol], 50.59 [OCH3], 20.77 [CH3, pTol]. Anal. Calcd for
Rea ction of 1 w ith Dim eth yla cetylen ed ica r boxyla te.
MeO2CCtCCO2Me (10 µL, 0.083 mmol) was added to a
solution of 1 (0.050 g, 0.083 mmol) in THF (10 mL). The color
of the solution changed instantaneously from green to red.
Volatiles were removed under vacuum, and the solid was
redissolved in CH2Cl2 (10 mL). Slow diffusion of hexanes into
this solution at room temperature afforded red crystals of 4a .
Yield: 0.047 g, 84%. IR (THF): 1921, 1852. 1H NMR (CD2-
Cl2): 13.91 [s, br, 1H, OH], 8.86 [m, 1H, bipy], 8.46 [m, 1H,
bipy], 7.94 [m, 2H, bipy], 7.48 [m, 3H, bipy], 7.17 [m, 1H, bipy],
6.48 [m, 4H, pTol], 3.66 [s, 3H, OCH3], 3.37 [s, 3H, OCH3],
2.06 [s, 3H, CH3, pTol]. 13C{1H} NMR (CD2Cl2): 269.10 [Red
C], 205.08 [CO], 199.58 [CO], 171.40 [CdO], 168.29 [NCdC],
165.71 [CdO], 156.66, 154.07, 153.78, 152.36 [bipy], 143.13
[C(OH)C(CO2Me)], 138.18, 135.66 [bipy], 134.88, 128.95 [pTol],
126.91, 126.45 [bipy], 124.48 [pTol], 122.44, 122.28 [bipy],
113.55 [pTol], 51.89 [OCH3], 51.08 [OCH3], 25.94 [CH3, pTol].
Anal. Calcd for C26H22N3O7Re: C, 46.28; H, 3.28; N, 6.22.
Found: C, 46.37; H, 3.19; N, 6.35.
C
24H20N3O5Re: C, 46.74; H, 3.26; N, 6.81 Found: C, 46.64; H,
3.29; N, 6.69.
Rea ction by Dep r oton a tion /Meth yla tion of 4a . KN-
(SiMe3)2 (0.150 mL of a 0.5 M solution in toluene, 0.074 mmol)
was added to a solution of 4a (0.050 g, 0.074 mmol) in THF
(15 mL) previously cooled at -78 °C. The color of the solution
darkened inmediately. MeOTf (8.4 µL, 0.074 mmol) was added
at -78 °C, and the mixture was stirred and allowed to reach
room temperature. The solvent was removed under vacuum.
The red residue was extracted with CH2Cl2 (2 × 10 mL). The
resulting solution was concentrated to 5 mL. Slow diffusion
of hexanes into this solution at room temperature afforded 5
as a red microcrystaline solid. Yield: 0.037 g, 74%. IR (THF):
Rea ction of 1 w ith Dieth yla cetylen ed ica r boxyla te.
Following the procedure described for 4a , the reaction of 1
(0.050 g, 0.083 mmol) with EtO2CCtCCO2Et (13 µL, 0.083
mmol) afforded red crystals of 4b, one of which was suitable
(27) Taylor, E. C.; McKillop, A.; Hawks, G. H. Organic Syntheses;
Wiley: New York, 1980; Vol. VI, p 549.

Amido Complex [Re(NHpTol)(CO)3(bipy)]
Organometallics, Vol. 22, No. 2, 2003 263
1914, 1841. 1H NMR (CD2Cl2): 8.92 [m, 1H, bipy], 8.57 [m,
1H, bipy], 8.03 [m, 2H, bipy], 7.60 [m, 3H, bipy], 7.17 [m, 1H,
bipy], 6.57 [m, 4H, pTol], 4.42 [s, 3H, RedCOCH3], 3.65 [s,
3H, OCH3], 3.36 [s, 3H, OCH3], 2.10 [s, 3H, CH3, pTol]. 13C-
{1H} NMR(CD2Cl2): 272.65 [RedC], 205.63 [CO], 197.61 [CO],
173.24 [CdO], 166.04 [NCdC], 165.01 [CdO], 156.66, 154.27,
152.44, 151.23 [bipy], 143.98 [C(OMe)dC(CO2Me)], 138.83,
136.32 [bipy], 134.37, 129.11 [pTol], 127.17, 126.72 [bipy],
122.85 [pTol], 122.71, 122.26 [bipy], 118.68 [pTol], 66.74 [Red
COCH3], 51.69 [OCH3], 50.72 [OCH3], 20.71 [CH3, pTol]. Anal.
Calcd for C27H24N3O7Re: C, 47.08; H, 3.51; N, 6.10 Found: C,
47.14; H, 3.58; N, 6.09.
Ack n ow led gm en t. We thank Ministerio de Ciencia
y Tecnolog´ıa and Ministerio de Educacio´n for support
of this work (Projects MCT-00-BQU-0220, PB97-0470-
C02-01 and PR-01-GE-7) and a predoctoral fellowship
(to E.H.).
Su p p or tin g In for m a tion Ava ila ble: Tables giving posi-
tional and thermal parameters, bond distances, and bond
angles for 2, 3, and 4b. This material is available free of charge
via the Internet at http://pubs.acs.org.
OM020667P