New octahedral rhenium(I) tricarbonyl amido complexes

Article abstract of DOI:10.1021/om0110383

Several new Re(I) octahedral amido complexes fac-[Re(NRR′)(CO)₃(N-N)] (R = aryl; R′ = H, aryl; N-N = 2,2′-bipyridine, bipy; 1,10-phenanthroline, phen) have been synthesized either by reaction of [Re(OTf)CO)₃-(N-N)] precursors with po

Full text of DOI:10.1021/om0110383

1966
Organometallics 2002, 21, 1966-1974
New Octa h ed r a l Rh en iu m (I) Tr ica r bon yl Am id o
Com p lexes
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 December 5, 2001
Several new Re(I) octahedral amido complexes fac-[Re(NRR′)(CO)3(N-N)] (R ) aryl; R′ )
H, aryl; N-N ) 2,2′-bipyridine, bipy; 1,10-phenanthroline, phen) have been synthesized either
by reaction of [Re(OTf)(CO)3(N-N)] precursors with potassium amides or by deprotonation
of [Re(NH2Ar)(CO)3(N-N)]OTf compounds, in turn obtained by reaction of [Re(OTf)(CO)3-
(N-N)] compounds with amines. The structure of the amido complexes [Re(NHPh)(CO)3-
(bipy)] (5) and [Re(NPh2)(CO)3(bipy)] (6) have been determined by single-crystal X-ray
diffraction. The results, coupled with the solution NMR behavior of the complexes, indicate
that the delocalization of the nitrogen lone pair of the amido group involves mainly the
N-aryl bonds. Amido complexes [Re(NHp-Tol)(CO)3(N-N)] (4a ,b) (p-Tol ) 4-methylphenyl)
react with 4-ethylphenol, with ethanothiol, and with diphenylphosphine to give the complexes
[Re(OC6H4-4-C2H5)(CO)3(bipy)] (8), [Re(SCH2CH3)(CO)3(bipy)] (9), and [Re(PPh2)(CO)3(N-
N)] (10a ,b). The structure of the diphenylphosphido complex [Re(PPh2)(CO)3(phen)] (10b),
determined by X-ray diffraction, was compared with the structure of the homologous
diphenylamido complex 6. The different geometries (pyramidal phosphorus and planar amido
nitrogen) correlate with the higher nucleophilicity of the phosphido complex.
In tr od u ction
ity: the nitrogen atom should possess a high basicity
and nucleophilicity, and the repulsion between the
nitrogen lone pair and the metal filled orbitals should
make the M-N bond very reactive. Actually, a mean-
ingful discussion of the M-N distances requires the
comparison between structures determined with a high
accuracy, which are not always available. Furthermore,
the relationship between the degree of multiplicity of
the M-N bond and the M-N distance may be compli-
cated by steric factors. This is of particular importance
when a metal center has both a high coordination
number and very bulky ligands, which are often used
to stabilize the amido complexes. This situation is
typically found in d6 octahedral amido complexes, which
are the most relevant to the work described here.2-5
Amido complexes of late transition metals in low
oxidation states have been the subject of much research1
due to (a) the earlier belief that these compounds would
be inherently unstable as a result of the mismatch
between the soft metal fragment and the hard amido
ligand and (b) the interesting reactivity displayed by
some of these species. Although it is now recognized that
no thermodynamic instability is necessarily attached to
this type of complex, their syntheses remain challenging
due to undesirable side reactions brought about by the
strongly basic or reducing character of the reagents.
In its simple description, the metal-amido bond can
be considered to consist of (a) a σ bond like the M-C
bond in metal alkyls, and (b) a π bond due to donation
of an electron pair from the nitrogen atom into a
suitable empty d orbital of the metal fragment. This
second component is important in amido complexes of
early transition metals of intermediate or high oxidation
states. However, for 18-electron low-valent transition
metal amido complexes, at least formally, this π dona-
tion should not be possible and, therefore, the amido
ligand should be pyramidal, and the metal-nitrogen
distance should correspond to a single bond. In turn,
this should have important consequences on the reactiv-
(2) Re(I) amido complexes: (a) Dewey, M. A.; Arif, A. M.; Gladysz,
J . A. J . Chem. Soc., Chem. Commun. 1991, 712-714. (b) Dewey, M.
A.; Knight, D. A.; Arif, A.; Gladysz, J . A. Chem. Ber. 1992, 125, 815-
824. (c) Dewey, M. A.; Stark, G. A.; Gladysz, J . A. Organometallics
1996, 15, 4798-4807. (d) Simpson R. D.; Bergman, R. G. Organome-
tallics 1992, 11, 3980-3993.
(3) Ru(II) amido complexes: (a) Bryndza, H. E.; Fong, L. K.; Paciello,
R. A.; Tam, W.; Bercaw, J . E. J . Am. Chem. Soc. 1987, 109, 1444-
1456. (b) Hartwig, J . F.; Andersen, R. A.; Bergman, R. G. J . Am. Chem.
Soc. 1989, 111, 2717-2719. (c) Hartwig, J . F.; Andersen, R. A.;
Bergman, R. G. Organometallics 1991, 10, 1875-1887. (d) J oslin, F.
L.; J ohnson, M. P.; Mague, J . T.; Roundhill, D. M. Organometallics
1991, 10, 2781-2794. (e) Hsu, G. C.; Kosar, W. P.; J ones, W. D.
Organometallics 1994, 13, 385-396. (f) Kaplan, A. W.; Ritter, J . C.
M.; Bergman, R. G. J . Am. Chem. Soc. 1998, 120, 6828-6829. (g)
Boncella, J . M.; Eve, T. M.; Rickman, B.; Abboud, K. A. Polyhedron
1998, 17, 725-736. (h) Fulton, J . R.; Bouwkamp, M. W.; Bergman, R.
G. J . Am. Chem. Soc. 2000, 122, 8799-8800. (i) J ayaprakash, K. N.;
Gunnoe, T. B.; Boyle, P. D. Inorg. Chem. 2001, 40, 6481-6486.
(4) Os(II) amido complexes: Flood, T. C.; Lim, J . K.; Deming, M.
A.; Keung, W. Organometallics 2000, 19, 1166-1174.
* Corresponding author. E-mail: japm@sauron.quimica.uniovi.es.
(1) (a) Chisholm, M. H. Comprehensive Inorganic Chemistry; Wilkin-
son, G., Gillard, R. D., McCleverty, J . A., Eds.; Pergamon Press:
Oxford, U.K., 1987; Vol. 2, pp 161-188. (b) Bryndza, H. E.; Tam, W.
Chem. Rev. 1988, 88, 1163-1188. (C) Fryzuk, M. D.; Montgomery, C.
D. Coord. Chem. Rev. 1989, 95, 1-40.
10.1021/om0110383 CCC: $22.00 © 2002 American Chemical Society
Publication on Web 04/04/2002

Octahedral Rhenium(I) Tricarbonyl Amido Complexes
Organometallics, Vol. 21, No. 9, 2002 1967
Sch em e 1
With regard to the geometry of the amido ligand, most
complexes of this sort are planar at the nitrogen,6 a fact
usually interpreted in terms of electron delocalization
involving the R groups on the amido nitrogen, and that
is most significant when R ) aryl, C(O)R, and SiR3.1c
Nevertheless, these d6 octahedral amido complexes
display a rich reactivity. We have begun to explore the
synthesis, structure, and reactivity of amido complexes
of the metal fragment {Re(CO)3(bipy)}, and here we
report our first results.
Octahedral Re(I) derivatives fac-[ReX(CO)3(bipy)] (X
) anionic ligand) have been extensively studied within
the fields of photophysics7 and CO2 activation,8 whereas
their application in other areas has been somewhat
limited.9 In particular, no amido derivatives of this kind
were known. We felt that amido complexes [Re(NRR′)-
(CO)3(bipy)], if they could be prepared, would be attrac-
tive for several reasons: (a) {Re(CO)3(bipy)} fragments
are rather inert, thus eliminating possible side reac-
tions, including facile descomposition pathways. (b)
Given the very strong preference for a fac geometry and
the planarity of the bipy ligand, steric hindrance would
be, unlike in most isolable low-valent amido complexes,
virtually absent, a feature that would simplify the
analysis of the influence of the electronic properties and
that, coupled with the fact that no NfRe π-donation
would be possible for these 18-electron species, should
enhance their reactivity.
halo complexes are unreactive toward the amide re-
agent. Complex 1a is rather thermally stable and can
be stored under nitrogen several months. Alternatively,
it can be generated by reaction of [ReCl(CO)3(bipy)] with
silver triflate and, once the AgBr byproduct was re-
moved by filtration, used without isolation for the
synthesis of the amido complexes. We initially employed
lithium amides as reagents for the preparation of amido
complexes. However, only oily materials could be ob-
tained. Similar difficulties, attributed to the presence
of lithium triflate, were experienced by Gladysz during
the purification of [ReCp(NRR′)(NO)(PPh3)] complexes.2b
The complete elimination of LiOTf is difficult due to its
appreciable solubility in the solvents into which the
amido complexes can be extracted. Hence, we turned
our attention to potassium amides, generated by in situ
deprotonation of amines with KN(SiMe3)2. The lower
solubility of KOTf allowed the isolation of the amido
complexes as microcrystalline solids. However, when
this method was applied to the synthesis of the aryla-
mido compounds [Re(NHAr)(CO)3(bipy)] (Ar ) p-Tol,
1
Ph), the H NMR of the products showed the contami-
nation with traces of unidentified species. Therefore, we
sought an alternative method.
The triflato complex 1a reacts with arylamines NH2p-
Tol and NH2Ph to give the salts [Re(NH2p-Tol)(CO)3-
(bipy)]OTf (2a ) and [Re(NH2Ph)(CO)3(bipy)]OTf (3). The
facile substitution of the triflate group in 1a using
stoichiometric amounts of arylamine and mild condi-
tions (1 h, room temperature) contrasts with the previ-
ously reported substitution using PPh3, which required
100 equiv of triphenylphosphine.11 This difference can
be attributed to the higher basicity and lower steric bulk
of the primary amines.
The treatment of 2a and 3 with KN(SiMe3)2 in THF
at -78 °C afforded the amido complexes [Re(NHp-Tol)-
(CO)3(bipy)] (4a ) and [Re(NHPh)(CO)3(bipy)] (5), respec-
tively (see Scheme 1), which could be isolated as
spectroscopically pure compounds. The deprotonation of
coordinated amines in cationic complexes was previously
used as a route to amido complexes and, in some
instances, was found to be preferable to the employment
of preformed alkaline amides.12
Resu lts a n d Discu ssion
We have found that arylamido complexes [Re(NRAr)-
(CO)3(bipy)] (R ) H, Ph, 4-MeC6H4 (p-Tol)) can be
prepared by two methods. The first method is the
reaction of the triflato complex [Re(OTf)(CO)3(bipy)]10
(1a ) with potassium amides. The employment of the
more labile triflato complex as precursor was found to
be necessary given that [ReX(CO)3(bipy)]11 (X ) Cl, Br)
(5) Ir(III) amido complexes: (a) Glueck, D. S.; Winslow, L. J . N.;
Bergman, R. G. Organometallics 1991, 10, 1462-1479. (b) Glueck, D.
S.; Bergman, R. G. Organometallics 1991, 10, 1479-1486. (c) Woerpel,
K. A.; Bergman, R. G. J . Am. Chem. Soc. 1993, 115, 7888-7889.
(6) We are aware of only two exceptions; see refs 2a-c and 3i.
(7) See for instance: (a) Stufkens, D. J .; Vlcek, A., J r. Coord. Chem.
Rev. 1998, 177, 127-179. (b) Farrell, I. R.; Vlcek, A., J r. Coord. Chem.
Rev. 2000, 208, 87-101. (c) Striplin, D. R.; Crosby, G. A. Coord. Chem.
Rev. 2001, 211, 163-175.
(8) (a) Kutal, C.; Weber, M. A.; Ferraudi, G.; Geiger, D. Organome-
tallics 1985, 4, 2161-2166. (b) Sullivan, B. P.; Meyer, T. J . Organo-
metallics 1986, 5, 1500-1505. (c) Kutal, C.; Corbin, J .; Ferraudi, G.
Organometallics 1987, 6, 553-557. (d) Scheiring, T.; Klein, A.; Kaim,
W. J . Chem. Soc., Perkin Trans. 2 1997, 2569-2571.
The IR spectra of 4a and 5 displayed three νCO bands
typical of fac-tricarbonyl compounds, with wavenumber
values some 30 cm-1 lower than the precursor amino
complexes, reflecting the transformation of cationic
species into neutral ones.
(9) Gibson, D. H.; Sleaad, B. A.; Yin, X.; Vij, A. Organometallics
1998, 17, 2689-2691.
(10) Triflato complexes of this kind have been previously prepared.
See for instance: Guerrero, J .; Pino, O. E.; Wolcan, E.; Feliz, M. R.;
Ferraudi, G.; Moya, S. A. Organometallics 2001, 20, 2842-2853.
(11) Klein, A.; Vogler, C.; Kaim, W. Organometallics 1996, 15, 236-
244.
(12) Martin, G. C.; Palenik, G. J .; Boncella, J . M. Inorg. Chem. 1990,
29, 2027-2030.

1968 Organometallics, Vol. 21, No. 9, 2002
Hevia et al.
Sch em e 2
Sch em e 3
The most relevant features in the NMR spectra of the
new compounds are the broad signals at 5.51 (2a ) and
4.78 (3) ppm, and the broad singlets at 2.15 ppm (4a )
and 2.11 ppm (5), assigned to the nitrogen-bonded
hydrogens.13
Diarylamines Ph2NH and p-Tol2NH did not react with
[Re(OTf)(CO)3(bipy)] (1a ) under the conditions used for
the synthesis of the primary amine complexes, surely
due to the lower basicity and larger bulk of the diary-
lamines. Fortunately, the reaction of 1a with the potas-
sium diarylamides yielded the diarylamido complexes
[Re(NPh2)(CO)3(bipy)] (6) and [Re(Np-Tol2)(CO)3(bipy)]
(7), which could be purified by filtration followed by
crystallization.
We have begun to study the reactivity of the new
amido complexes. The p-tolylamido complex 4a does not
react with an excess (10 equiv) of methanol or water (5
h, room temperature, THF). This contrasts with the
reactivity toward methanol shown by Bergman’s com-
plex [Re(NHPh)(CO)3(depe)].2d Complex 4a reacted with
4-ethylphenol to yield the orange aryloxo complex [Re-
(OAr)(CO)3(bipy)] (8) (Ar ) 4-ethylphenyl) and with
ethanethiol to give the red thiolato complex [Re(SEt)-
(CO)3(bipy)] (9) (see Scheme 3 and Experimental Sec-
tion). The reaction of 4a with an equimolar amount of
diphenylphosphine in THF at room temperature af-
forded the diphenylphosphido complex [Re(PPh2)(CO)3-
(bipy)] (10a ). The reaction was accompanied by a color
change from emerald green to deep blue. The 31P NMR
chemical shift of the singlet of 10a (-43.09 ppm) is close
to that of free diphenylphosphine (-40.55 ppm), in
accordance with the data of previously reported rhenium
terminal phosphido complexes.14 When the reaction
between 4a and HPPh2 was carried out in an NMR tube
F igu r e 1. Thermal ellipsoid plot (ellipsoids at 30% prob-
ability level) of 5.
1
in C6D6, the H NMR spectrum of the resulting solution
showed the presence of free p-toluidine in addition to
the signals of 10a . Although bridging phosphido com-
plexes are relatively abundant, only a few terminal
examples have been fully characterized, including the
rhenium(I) complex [ReCp(PPh2)(NO)(PPh3)].14a-c This
preparation of phosphido complexes 10a ,b is reminis-
cent of the reaction between the methoxo complex [Re-
(OMe)(CO)3(depe)] and HPPh2 to afford the phosphido
complex [Re(PPh2)(CO)3(depe)].2d
The structures of the amido complexes 5 and 6 were
determined by single-crystal X-ray diffraction (Figures
1 and 3 and Tables 1 and 3). For comparative purposes,
(13) The chemical shift of N-H hydrogens of amido complexes has
been reported to appear over a wide range of values; see for instance:
(a) Powell, K. R.; Pe´rez, P. J .; Luan, L.; Feng, S. G., White, P. S.;
Brookhart, M.; Templeton, J . L. Organometallics 1994, 13, 1851-
1864: 15.33 and 13.00 ppm for the major and minor rotational isomers
of [WTp′(NHPh)(CO)2]. (b) VanderLende, D. D.; Abboud, K. A., Boncella
J . M. Inorg. Chem. 1995, 34, 5319-5326: 0.18 ppm for trans-[Ni(Ph)-
(NHPh)(PMe3)2].
(14) See ref 2d and: (a) Buhro, W. E.; Georgiou, S.; Hutchinson, J .
P.; Gladysz, J . A. J . Am. Chem. Soc. 1985, 107, 3346-3348. (b) Buhro,
W. E.; Gladysz, J . A. Inorg. Chem. 1985, 24, 3507-3508. (c) Buhro,
W. E.; Zwick, B. D.; Georgiou, S.; Hutchinson, J . P.; Gladysz, J . A. J .
Am. Chem. Soc. 1988, 110, 2427-2439, and references therein.

Octahedral Rhenium(I) Tricarbonyl Amido Complexes
Organometallics, Vol. 21, No. 9, 2002 1969
Ta ble 1. Selected Bon d Dista n ces a n d An gles for
Com p lex 5
(1.898(5) and 1.901(5) Å). Since the comparison is
between the Re-CO distances of the three carbonyl
ligands each trans to a nitrogen atom, the difference
reflects the larger trans influence of the amido group.
The amido ligand of 5, as in nearly all the previously
known amido complexes structurally characterized, is
planar at nitrogen6 (the sum of the angles about N is
360.1°).
Bond Distances (Å)
Re(1)-C(1)
Re(1)-C(2)
Re(1)-C(3)
Re(1)-N(1)
Re(1)-N(2)
1.901(5)
1.898(5)
1.925(5)
2.182(3)
2.188(4)
Re(1)-N(3)
N(3)-C(21)
C(1)-O(1)
C(2)-O(2)
C(3)-O(3)
2.112(4)
1.360(5)
1.156(5)
1.152(5)
1.154(6)
Bond Angles (deg)
The Re-N(amido) distance (2.112(4) Å) in 5 is some-
what shorter than the Re-N(bipy) distances (2.182(3)
and 2.188(4) Å) in the same complex and then the Re-
N(amine) distance (2.250(3) Å) in 2a . The Re-N(amido)
bond has some degree of ionic component, which is
known to shorten the bond lengths.15 Moreover, a dative
(as opossed to covalent) bond, like Re-N(bipy), usually
gives larger bond lengths. Therefore, multiple character
of the Re-N(amido) bond does not need to be invoked
to account for the difference in Re-N bond lengths.
C(1)-Re(1)-C(2)
C(2)-Re(1)-C(3)
C(1)-Re(1)-C(3)
90.0(2)
C(1)-Re(1)-N(2)
173.09(16)
97.22(18)
93.75(17)
175.85(17)
83.69(14)
82.94(14)
86.74(19) C(2)-Re(1)-N(3)
87.47(18) C(1)-Re(1)-N(3)
C(2)-Re(1)-N(1) 170.21(16) C(3)-Re(1)-N(3)
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)
99.71(17) N(3)-Re(1)-N(1)
92.20(16) N(3)-Re(1)-N(2)
96.45(17) Re(1)-N(3)-C(21) 134.9 3)
95.42(15) H(3)-N(3)-C(21)
73.95(13) Re(1)-N(3)-H(3)
111.1(9)
114.1(7)
The 1H NMR spectra of [Re(NHp-Tol)(CO)3(bipy)] (4a )
and [Re(NHPh)(CO)3(bipy)] (5) each show one set of four
1
multiplets for the bipy ligand. Given that the H NMR
spectrum of 4a is more informative, variable-tempera-
ture experiments were carried out with this complex.
1
The bipy signals in the H NMR of 4a remain invariant
between 25 and -80 °C. This is consistent with free
rotation around the Re-N(amido) bond over this tem-
perature range or with a static structure with the amido
group lying in the mirror plane of the {Re(CO)3(bipy)}
fragment. Since there is neither steric hindrance nor π
donation from the amido lone pair to the metal dp
orbitals (filled in these d6 complexes), free rotation
seems to be the more plausible explanation.
The Re-N(amido) distance in 5 (2.112(4) Å) is slightly
shorter than in the structurally similar complex [Re-
(NHPh)(CO)3(depe)]2d (2.170(4) Å), a fact that can be
attributed to the steric bulk of the diphosphine depe
(1,2-diethylphosphinoethane), both P atoms of which are
adjacent to the amido group in this complex. A slightly
shorter Re-N(amido) distance was found in the complex
[ReCp(NHPh)(NO)(PPh3)]2a,b (2.076(6) Å), which fea-
tures a pyramidal amido ligand and for which, therefore,
the lack of multiple character for the Re-N bond is well
established. The longer Re-N distance of 5 should, at
least in part, be due to the presence of a CO ligand (with
a strong trans influence) in the position trans to the
amido group in the octahedral molecule of 5.
F igu r e 2. Thermal ellipsoid plot (ellipsoids at 30% prob-
ability level) of 2a .
Ta ble 2. Selected Bon d Dista n ces a n d An gles for
Com p lex 2a
Bond Distances (Å)
Re(1)-C(1)
Re(1)-C(2)
Re(1)-C(3)
Re(1)-N(1)
Re(1)-N(2)
1.926(6)
1.915(5)
1.934(6)
2.162(4)
2.163(4)
Re(1)-N(3)
N(3)-C(21)
C(1)-O(1)
C(2)-O(2)
C(3)-O(3)
2.250(3)
1.488(6)
1.141(6)
1.144(6)
1.132(7)
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)
89.0(2)
88.6(2)
85.8(2)
N(1)-Re(1)-N(2)
C(1)-Re(1)-N(2)
C(2)-Re(1)-N(3)
74.96(16)
94.72(17)
92.18(18)
178.83(16)
94.16(19)
84.78(14)
84.14(15)
An interesting comparison can be made between the
structures of the aminocomplex 2a and the amido
derivative 5. The N-C(ipso) distance in 5 (1.360(5) Å)
is significantly shorter than the corresponding distance
in 2a (1.488(6) Å), which in turn is similar to the value
found for other structurally characterized rhenium
aniline complexes (1.444(6) Å in [Re(NH2Ph)(NPh)-
Cl3]).16 This indicates that substantial delocalization of
the nitrogen lone pair takes place involving the phenyl
group, a fact that explains why the amido group is
planar at the nitrogen in this 18-electron compound. The
lone pair delocalization involving the N-Ar bond is
97.27(19) C(1)-Re(1)-N(3)
95.19(17) C(3)-Re(1)-N(3)
C(3)-Re(1)-N(1) 174.1(2)
N(1)-Re(1)-N(3)
C(2)-Re(1)-N(2) 171.64(19) N(2)-Re(1)-N(3)
C(3)-Re(1)-N(2) 99.1(2)
C(21)-N(3)-Re(1) 111.9(3)
the structure of the amino complex 2a was also deter-
mined (Figure 2 and Table 2). The three derivatives
have the expected octahedral geometry around the
rhenium atom, the major deviation from an idealized
octahedral geometry being the small (74-75°) angle
subtended by Re and the bipy nitrogens, imposed by the
rigid geometry of the chelate.
1
further substantiated by the variable-temperature H
NMR behavior of complex 4a . At room temperature, an
For complex 5, the distance between rhenium and the
carbon atom of the carbonyl ligand trans to the amido
group (1.925(5) Å) is appreciably longer than the cor-
responding distances for the other two CO groups
(15) Holland, P. L.; Andersen, R. A.; Bergman, R. G. Comments
Inorg. Chem. 1999, 21, 115-129.
(16) Rossi, R.; Marchi, A.; Duatti, A.; Magon, L.; Casellato, U.;
Graziani, R. Inorg. Chim. Acta 1988, 142, 23-25.

1970 Organometallics, Vol. 21, No. 9, 2002
Hevia et al.
Ta ble 3. Selected Bon d Dista n ces a n d An gles for
Com p lex 6
Bond Distances (Å)
Re(1)-C(1)
Re(1)-C(2)
Re(1)-C(3)
Re(1)-N(1)
Re(1)-N(2)
Re(1)-N(3)
1.920(3)
1.933(4)
1.905(3)
2.178(3)
2.197(3)
2.201(2)
N(3)-C(21)
N(3)-C(27)
C(1)-O(1)
C(2)-O(2)
C(3)-O(3)
1.384(4)
1.433(4)
1.153 (4)
1.142(4)
1.157(4)
Bond Angles (deg)
C(1)-Re(1)-C(2)
C(3)-Re(1)-C(2)
C(3)-Re(1)-C(1)
88.57(13) C(1)-Re(1)-N(2)
86.11(14) C(2)-Re(1)-N(3)
87.98(13) C(1)-Re(1)-N(3)
92.37(11)
95.69(12)
175.46(11)
93.90(12)
83.50(9)
C(2)-Re(1)-N(1) 174.80(12) C(3)-Re(1)-N(3)
C(1)-Re(1)-N(1)
C(3)-Re(1)-N(1)
92.12(11) N(1)-Re(1)-N(3)
99.06(12) N(2)-Re(1)-N(3)
85.30(10)
C(2)-Re(1)-N(2) 100.47(12) C(21)-N(3)-Re(1) 129.8(2)
C(3)-Re(1)-N(2) 173.41(12) C(27)-N(3)-Re(1) 114.81(18)
N(1)-Re(1)-N(2)
74.35(10) C(21)-N(3)-C(27) 115.1(2)
Re-C(2) (1.933(4) Å) and Re-N(2) (2.197(3) Å) are
longer than the “equivalent” Re-C(3) (1.905(3) Å) and
Re-N(1) (2.178(3) Å) (which are almost identical to the
distances found in 5).
The amido ligand in 6 is planar at the nitrogen, with
a Re-N distance of 2.201(2) Å. The longer distance
with respect to 5 is due to the lower basicity and larger
bulk of the diphenylamido ligand, but given the planar-
ity of the bipy ligand and the octahedral geometry of
the complex, the steric factor must be of minor impor-
tance.
With regard to the basicity, it should be noted that
for 6 two aromatic rings are available for the resonance
delocalization of the nitrogen lone pair. As a result, the
N-C(ipso) distance in complex 5, with only one aromatic
ring, (1.360(5) Å), is shorter than any of the N-C(ipso)
distances in the diphenylamido complex 6 (1.384(4) and
1.433(4) Å). The difference found between the two
N-C(ipso) distances in complex 6 can be interpreted as
indicating that one of the phenyl rings (the one with
the shorter N-C distance) is significantly more engaged
in the delocalization. This ring lies in the plane defined
by Re, N(amido), and C(ipso) (see Figure 3), thus
maximizing the delocalization. The presence of four
F igu r e 3. Thermal ellipsoid plot (ellipsoids at 30% prob-
ability level) of 6.
1
signals for the bipy hydrogens in H NMR, five singlets
AA′BB′ quartet in the 1H NMR spectrum is observed
for the four aromatic hydrogen atoms of the p-tolyl
group. This pattern changes when the temperature is
lowered, indicating that the rotation around the N-C(ip-
so) bond is being frozen. At -80 °C the p-tolyl region of
the spectrum displays three signals; one of them (6.72
ppm), integrating as two hydrogens, is assigned to one
ortho and one meta hydrogen, whereas the two remain-
ing hydrogens give two signals at 6.37 and 5.75 ppm.17
This pattern is similar to the one found at intermediate
temperatures for the amido complex trans-[PtCl{NH-
(4-I-C6H4)}(PEt3)2].18
In the solid-state structure of [Re(NPh2)(CO)3(bipy)]
(6) (see Figure 3), the ortho hydrogen on C(26) is close
to one of the bipy nitrogens (N(2)-H(26) ) 2.851(9) Å)
and to one of the carbonyl carbons (C(2)-H(26) ) 2.549-
(9) Å),19 as shown in Figure 3. This weak interaction
seems to affect the Re-N and Re-C distances, since
for the bipy carbons in the 13C{H} NMR, and only one
13C NMR signal for the two carbonyl ligands trans to
the bipy nitrogens, maintained at -80 °C in complex 6,
is interpreted, reasoning as for complex 5 (see above),
as due to free rotation around the Re-N(amido) bond.
Variable-temperature 1H NMR of [Re(Np-Tol2)(CO)3-
(bipy)] (7) showed the presence of only one methyl
singlet and only one AA′BB′ quartet at temperatures
as low as -80 °C, indicating a similar behavior. In
addition, between room temperature and -80 °C, the
two phenyl groups of 6 appear as only four signals in
the 13C{H} NMR, reflecting that the two ortho carbons
and the two meta carbons of each ring are equivalent
over this temperature range. Thus, free rotation around
the N-C(ipso) bonds must be assumed.
(19) Similar distances have been found in a search through the
Cambridge Structural Database for three-center interactions between
a nitrogen, a carbonyl ligand, and an ortho phenyl hydrogen; see, for
instance: (a) Alonso, F. J . G.; Sanz, M. G.; Riera, V.; Abril, A. A.;
Tiripicchio A.; Ugozzoli, U. Organometallics 1992, 11, 801-806. (b)
Gargulak, J . D.; Gladefelter, W. L. Inorg. Chem. 1994, 33, 253-257.
(c) Cook, J .; Davison, A.; Davis, W. M.; J ones, A. G. Organometallics
1995, 14, 650-654.
(17) Variable-temperature 1H NMR spectra of 4a are given as
Supporting Information.
(18) Albe´niz, A. C.; Calle, V.; Espinet, P.; Go´mez, S. Inorg. Chem.
2001, 40, 4211-4216.

Octahedral Rhenium(I) Tricarbonyl Amido Complexes
Organometallics, Vol. 21, No. 9, 2002 1971
Ta ble 4. Selected Bon d Dista n ces a n d An gles for
Com p lex 10b
Bond Distances (Å)
Re(1)-C(1)
Re(1)-C(2)
Re(1)-C(3)
Re(1)-N(1)
Re(1)-N(2)
Re(1)-P(1)
1.930(10)
1.924(10)
1.894 (10)
2.190(7)
2.164(7)
2.571 (2)
P(1)-C(31)
P(1)-C(41)
C(1)-O(1)
C(2)-O(2)
C(3)-O(3)
1.833(9)
1.830(9)
1.164 (12)
1.125(11)
1.179(11)
Bond Angles (deg)
C(2)-Re(1)-C(1)
C(3)-Re(1)-C(2)
C(3)-Re(1)-C(1)
90.0(4)
89.7(3)
90.4(4)
C(1)-Re(1)-N(2)
C(2)-Re(1)-P(1)
C(1)-Re(1)-P(1)
96.2(4)
93.6(3)
176.0(4)
87.8(3)
91.59(19)
80.52(18)
C(2)-Re(1)-N(1) 174.80(12) C(3)-Re(1)-P(1)
C(1)-Re(1)-N(1)
C(3)-Re(1)-N(1) 172.5(4)
89.8(4)
N(1)-Re(1)-P(1)
N(2)-Re(1)-P(1)
C(2)-Re(1)-N(2)
C(3)-Re(1)-N(2)
N(1)-Re(1)-N(2)
97.8(4)
97.4(3)
75.1(3)
C(41)-P(1)-Re(1) 107.0(3)
C(31)-P(1)-Re(1) 112.8(3)
C(41)-P(1)-C(31) 103.7(4)
between the lone pair on the phosphorus atom and the
filled d orbitals of the metal fragment.14a-c Note that
the opposite is true for amido complexes, which feature
Re-N distances shorter than amino complexes, as
exemplified by the structures of 5 and 6 versus that of
2a (see above). An important consequence of this dif-
ference between homologous amido and phosphido
compounds is that, whereas amines are more nucleo-
philic than phosphines, the phosphido complexes are
more nucleophilic than the amido counterparts. Thus,
whereas [Re(NPh2)(CO)3(bipy)] (6) does not react with
methyl iodide (stoichiometric, room temperature, 24 h,
CD2Cl2 or THF), the phosphido complex 10a is instan-
taneously methylated by MeI (room temperature, THF)
to yield the salt [Re(PPh2Me)(CO)3(bipy)]I (11-I) (see
Scheme 4). With the stronger methylating agent MeOTf,
6 reacts (2 h in CD2Cl2 at room temperature) to give
[Re(OTf)(CO)3(bipy)] (1a ) plus free methyldipheny-
lamine; on the other hand, 10a reacts with MeOTf
(instantaneous at -78 °C, THF) to afford the salt [Re-
(PPh2Me)(CO)3(bipy)]OTf (11-OTf) (see Scheme 4).
These results reflect, besides the more nucleophilic
character of the phosphido complex, the better ability
of phosphorus to accommodate a higher coordination
number due to its larger size.22 Other aspects of the
reactivity of the new amido complexes are being studied
and will be the subject of a forthcoming paper.
F igu r e 4. Thermal ellipsoid plot (ellipsoids at 30% prob-
ability level) of 10b.
It was mentioned that, in the solid state, one of the
aryl rings of complex 6 is more involved in the delocal-
ization of the nitrogen lone pair. A good orbital overlap
requires this ring to lie in the plane defined by the
amido nitrogen and the two ipso carbons. Rotation of
that ring around the N-C(ipso) bond, found to occur in
solution, should result in loss of overlap and, therefore,
of lone pair delocalization through this aryl group.
However, the other ring is also rotating around the
N-C(ipso) bond. At a given point, this second ring would
lie in the NC2 plane, achieving maximum overlap for
the nitrogen lone pair delocalization. This process of
concordant rotation explains that the two aryl rings are
equivalent in solution, although the two N-C(ipso)
distances of 6 are so different in the solid state (see
above).
As few terminal phosphido compounds have been
crystallographically characterized, we sought to carry
out an X-ray analysis of complex 10a . All our attempts
to obtain single crystals of 10a suitable for X-ray
diffraction were unsuccessful. However, we found that
the phenanthroline complex [Re(PPh2)(CO)3(phen)] (10b),
prepared in a completely analogous manner and whose
spectroscopic data are very similar to those of 10a (see
Experimental Section), afforded X-ray quality crystals,
one of which was used for the determination of the
structure (see Figure 4 and Table 4).
In contrast with the planar diphenylamido ligand of
complex 6, the diphenylphosphido group of 10b is
pyramidal: the sum of the angles about phosphorus is
323.5°, nearly identical to what was found in the
complex [ReCp(PPh2)(NO)(PPh3)]14a-c (323°); this sum
would be 328.5° and 360° for idealized tetrahedral and
planar phosphorus atoms, respectively. Planar amido
and pyramidal phosphido ligands are the normally
encountered situations, and a discussion of the factors
leading to this difference has been given by Buhro.20
The Re-P distance (2.571(2) Å) is somewhat longer
than the Re-P distances found for phosphine com-
plexes,2d a fact that can be related to the repulsion
Exp er im en ta l Section
Gen er a l P r oced u r es. All manipulations were carried out
under dinitrogen using standard Schlenk techniques. Solvents
were distilled from Na (hexanes), Na/benzophenone (tetrahy-
drofuran and diethyl ether), and CaH2 (CH2Cl2). CD2Cl2 and
C6D6 were dried over 4 Å molecular sieves, and CD2Cl2 was
stored in the dark over Na2CO3. Elemental analyses were
obtained using a Perkin-Elmer 240-B microanalyzer. The IR
and 1H, 19F, 31P, and 13C NMR spectra were recorded on
Perkin-Elmer FT 1720-X (over the range 2200-1600 cm-1) and
Bruker AC-200 (or AC-300 or DPX-300) spectrometers, re-
spectively.
The complexes [Re(OTf)(CO)3(N-N)]10 (1a ,b) were prepared
in virtually quantitative yield by the reaction of equimolar
amounts of the corresponding [ReBr(CO)3(N-N)]11 compounds
with AgOTf in CH2Cl2 in the dark, followed by filtration
through diatomaceous earth to remove AgBr.
Cr ysta l Str u ctu r e Deter m in a tion for Com p ou n d s 2a ,
5, 6, a n d 10b. A suitable crystal was attached to a glass fiber
and transferred to a Bruker AXS SMART 1000 diffractometer
(20) Coel, S. C.; Chiang, M. Y.; Rauscher, D. J .; Buhro W. E. J . Am.
Chem. Soc. 1993, 115, 160-169.

1972 Organometallics, Vol. 21, No. 9, 2002
Hevia et al.
Sch em e 4
Ta ble 5. Cr ysta l Da ta a n d Refin em en t Deta ils for Com p lexes 2a , 5, 6, a n d 10b
2a
5
6
10b
formula
fw
C
21H17F3N3O6ReS
C23H22N3O4Re
590.64
C25H18N3O3Re
594.62
C29H22N2O3PRe‚1/2C4H8O
671.66
682.64
cryst syst
space group
a, Å
b, Å
c, Å
monoclinic
P21/c
18.5006(9)
9.9985(5)
13.0499(6)
90
95.4930(10)
90
2402.9(2)
4
monoclinic
C2/c
24.903(3)
11.8285(13)
18.891(2)
90
127.520(3)
90
4413.5(9)
8
monoclinic
P21/n
10.4605(8)
13.1053(10)
16.1229(12)
90
104.0680(10)
90
2144.0(3)
4
monoclinic
P21/c
14.237(8)
11.487(6)
19.161(11)
90
111.749(10)
90
2911(3)
R, deg
â, deg
γ, deg
V, Å3
Z
4
T, K
293(2)
1.887
1320
293(2)
1.778
2304
293(2)
1.842
1152
295(2)
1.533
1352
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
data/restraints/params
goodness-of-fit on F2
R1/Rw2 [I>2σ(I)]
R1/Rw2 (all data)
0.71073
0.32 × 0.21 × 0.11
5.209
1.11 e θ e 23.26
10 312
3458
3458/0/318
1.045
0.0256/0.0665
0.0279/0.0677
0.71073
0.45 × 0.22 × 0.18
5.541
2.01 e θ e 23.28
13 742
3169
3169/0/285
1.032
0.0228/0.0621
0.0268/0.0644
0.71073
0.71073
0.27 × 0.28 × 0.36
0.22 × 0.31 × 0.45
5.701
4.262
2.03 e θ e 23.32
9432
3095
3095/0/290
1.059
0.0156/0.0390
0.0175/0.0398
1.54 e θ e 23.66
12 756
4242
4242/0/344
1.014
0.0468/0.1222
0.0624/0.1357
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 SAINT21 program. The structure was solved by direct
methods with SHELXTL.22 A semiempirical absorption cor-
rection was applied with the program SADABS.23 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 5.
[Re(NH2p-Tol)(CO)3(bip y)]OTf (2a ). p-TolNH2 (0.010 g,
0.095 mmol) was added to a solution of [Re(OTf)(CO)3(bipy)]
(1a ) (0.050 g, 0.086 mmol) in CH2Cl2 (15 mL), and the mixture
was stirred for 1 h. The solvent was removed under vacuum,
and the yellow solid was washed with Et2O (2 × 5 mL) to give
the complex 2a . Slow diffusion of hexanes into a solution of
2a in CH2Cl2 at -20 °C afforded yellow crystals, one of which
was suitable for an X-ray analysis. Yield: 0.054 g, 92%. IR
(CH2Cl2): 2034, 1925. 1H NMR (CD2Cl2): 8.84, 8.25, 8.14, and
7.55 [m, 2H each, bipy], 6.85, 6.81, 6.40, and 6.36 [AA′BB′,
4H, C6H4], 5.51 [s, 2H, NH2], 2.23 [s, 3H, CH3]. 13C{1H}
NMR(CD2Cl2): 195.87 [2CO], 190.22 [CO], 156.32, 154.22, and
140.87 [bipy], 139.85 and 135.02 [pTol], 129.95 [bipy], 128.45
[pTol], 125.87 [q (361.78 Hz), CF3SO3], 124.16 [bipy], 120.09
[pTol], 20.73 [CH3]. 19F NMR(CD2Cl2): -78.57. Anal. Calcd for
21H17F3N3O6ReS: C, 36.94; H, 2.51; N, 6.85. Found: C, 36.47;
H, 2.62; N, 6.68.
C
[Re(NH2p-Tol)(CO)3(p h en )]OTf (2b). It was prepared as
described for 2a , starting from [Re(OTf)(CO)3(phen)] (2a )
(0.050 g, 0.083 mmol) and p-TolNH2 (0.010 g, 0.095 mmol).
Yield: 0.052 g, 88%, yellow. IR (CH2Cl2): 2033, 1923. 1H NMR
(CD2Cl2): 9.36, 9.21, 8.63, and 8.17 [m, 2H each, phen], 6.62,
6.58, 6.09, and 6.04 [AA′BB′, 4H, C6H4], 5.78 [s, 2H, NH2], 2.11
[s, 3H, CH3]. 19F NMR (CD2Cl2): -79.02. Anal. Calcd for
C23H17F3N3O6ReS: C, 39.09; H, 2.42; N, 5.94. Found: C, 39.21;
H, 2.50; N, 5.87.
[Re(NH2P h )(CO)3(bip y)]OTf (3). The previous procedure
was followed using [Re(OTf)(CO)3(bipy)] (1a ) (0.050 g, 0.086
mmol) in CH2Cl2 (15 mL) and PhNH2 (9 µL, 0.090 mmol) to
give the complex 3. Yield: 0.049 g, 85%, yellow. IR (CH2Cl2):
1
2034, 1925. H NMR (CD2Cl2): 8.80, 8.20, 8.09, and 7.54 [m,
2H each, bipy], 6.97 [m, 3H, C6H5], 6.24 [m, 2H, C6H5], 4.78
[s, 2H, NH2]. 19F NMR (CD2Cl2): -78.05. Anal. Calcd for
C
20H15F3N3O6ReS: C, 35.98; H, 2.26; N, 6.28. Found: C, 35.48;
H, 2.31; N, 6.49.
[Re(NHpTol)(CO)3(bip y)] (4a ). [Re(NH2p-Tol)(CO)3(bipy)]-
OTf (2a ) (0.050 g, 0.073 mmol) was dissolved in THF (10 mL),
and the solution was cooled to -70 °C. KN(SiMe3)2 (0.146 mL
of a 0.5 M solution in toluene, 0.073 mmol) was added. The
color of the solution changed from yellow to dark green. After
stirring for 15 min at -70 °C, the solution was allowed to warm
to room temperature. Volatiles were removed under vacuum,
the green solid was extracted with CH2Cl2 (2 × 10 mL), and
the solution was filtered using a cannula tipped with filter
paper. CH2Cl2 was removed under vacuum to afford 4a as an
(21) SAINT+. SAX area detector integration program, Version 6.02;
Bruker AXS, Inc.: Madison, WI, 1999.
(22) 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.
(23) Sheldrick, G. M. SADABS, Empirical Absorption Correction
Program; University of Go¨ttingen: Go¨ttingen, Germany, 1997.

Octahedral Rhenium(I) Tricarbonyl Amido Complexes
Organometallics, Vol. 21, No. 9, 2002 1973
emerald green solid. Crystallization of 4a was carried out in
THF/hexane, affording green crystals of 4a ‚THF. Yield: 0.033
4H, C6H4], 2.41 [q (7.5 Hz), 2H, CH2], 1.09 [t (7.5 Hz), 3H, CH3].
13C{1H} NMR (CD2Cl2): 199.59 [2CO], 196.71 [CO], 167.70
[Cipso, OC6H4Et], 153.09 and 139.66 [bipy], 130.66 and 128.19
[OC6H4Et], 127.29 [bipy], 123.52 [OC6H4Et], 119.91 [bipy],
28.15 [CH2CH3], 16.38 [CH2CH3]. Anal. Calcd for C21H17N2O4-
Re: C, 46.06; H, 3.12; N, 5.11. Found: C, 46.29; H, 3.70; N,
5.29.
1
g, 75%. IR (THF): 2003, 1899, 1884. H NMR (CD2Cl2): 9.01,
8.28, 8.12, and 7.55 [m, 2H each, bipy], 6.62, 6.58, 6.30, and
6.26 [AA′BB′, 4H, C6H4], 2.15 [s, 1H, NH], 2.05 [s, 3H, CH3].
13C{1H} NMR (CD2Cl2): 200.37 [2CO], 195.45 [CO], 155.53,
153.45, and 139.48 [bipy]. 138.76 and 129.58 [pTol], 127.58
[bipy], 127.10 [pTol], 123.67 [bipy], 116.14 [pTol], 20.23 [CH3].
Anal. Calcd for C24H24N3O4Re: C, 47.67; H, 4.00; N, 6.94.
Found: C, 47.29; H, 4.10; N, 6.79.
Rea ction of 4a w ith EtSH. EtSH (4 µL, 0.056 mmol) was
added to a solution of 4a (0.034 g, 0.056 mmol) in THF (10
mL), and the mixture was stirred for 40 min at room temper-
ature. The color of the solution changed from green to red.
Volatiles were removed under vacuum, and the red solid was
washed with Et2O (5 mL) to afford 9. Yield: 0.017 g, 66%, red.
IR (THF): 2005, 1904, 1888. 1H NMR (CD2Cl2): 9.03, 8.21,
8.07, and 7.51 [m, 2H each, bipy], 2.56 [q (7.5 Hz), 2H, SCH2-
CH3], 2.03 [t (7.5 Hz), 3H, SCH2CH3]. 13C{1H} NMR (CD2Cl2):
155.49, 153.33, 140.59, 127.11, and 123.59 [bipy], 25.46 [SCH2-
CH3], 21.49 [SCH2CH3]. Anal. Calcd for C15H13N2O3ReS: C,
36.95; H, 2.68; N, 5.74. Found: C, 36.68; H, 2.79; N, 5.60.
Insufficient solubility precluded the observation of CO signals.
[Re(NHpTol)(CO)3(p h en )] (4b). As described for 4a , 4b
was obtained using 2b (0.050 g, 0.070 mmol) and KN(SiMe3)2
(0.141 mL of a solution 0.5 M in toluene, 0.070 mmol).
Subsequent workup afforded 4b. Yield: 0.029 g, 74%, emerald
1
green. IR (THF): 2003, 1899, 1884. H NMR (CD2Cl2): 9.30,
8.55, 8.05, and 7.84 [m, 2H each, phen], 6.56, 6.53, 6.20, and
6.17 [AA′BB′, 4H, C6H4], 2.31 [s, 1H, NH], 2.22 [s, 3H, CH3].
Anal. Calcd for C22H16N3O3Re: C, 47.47; H, 2.89; N, 7.54.
Found: C, 47.09; H, 2.97; N, 7.41.
[Re(NHP h )(CO)3(bip y)] (5). Following the procedure de-
scribed for 4a ,b [Re(NH2Ph)(CO)3(bipy)]OTf (3) (0.050 g, 0.075
mmol) was dissolved in THF (10 mL) and KN(SiMe3)2 (0.150
mL of a solution 0.5 M in toluene, 0.075 mmol) was added at
-70 °C. Subsequent workup gave 5. Slow diffusion of hexanes
into a solution of 5 in THF at room temperature afforded dark
green crystals, one of which was used for X-ray analysis.
Yield: 0.031 g, 70%. IR (THF): 2002, 1897 1887. 1H NMR
(CD2Cl2): 8.96, 8.20, 8.06, and 7.51 [m, 2H each, bipy], 6.75
[m, 2H, C6H5], 6.32 [m, 2H, C6H5], 6.05 [m, 1H, C6H5], 2.11 [s,
1H, NH]. 13C{1H} NMR (CD2Cl2): 200.54 [2CO], 195.65 [CO],
160.53 [Ph], 155.46, 153.48, 139.51, and 129.11 [bipy], 127.65,
115.92, and 110.84 [Ph]. Anal. Calcd for C23H22N3O4Re: C,
46.77; H, 3.75; N, 7.11. Found: C, 46.57; H, 3.63; N, 7.31.
[Re(NP h 2)(CO)3(bip y)] (6). A solution of KNPh2 (prepared
by the reaction of NHPh2 (0.016 g, 0.094 mmol) and KN-
(SiMe3)2 (0.188 mL of a solution 0.5 M in toluene, 0.094 mmol)
in THF (5 mL) at -70 °C) was added to a solution of [Re(OTf)-
(CO)3(bipy)] (1a ) (0.050 g, 0.086 mmol) cooled to -70 °C. The
color of the solution changed from yellow to green. After 15
min stirring at low temperature, the mixture was allowed to
reach room temperature. Volatiles were removed under vacuum,
the green solid was extracted with CH2Cl2 (2 × 10 mL), and
the solution was filtered using a cannula tipped with filter
paper. Slow diffusion of hexanes into a solution of 6 in THF
at -20 °C afforded green crystals, one of which was used for
the X-ray analysis.Yield: 0.037 g, 72%. IR (THF): 2008, 1903,
1890. 1H NMR (CD2Cl2): 8.87 [m, 2H, bipy], 7.95 [m, 4H, bipy],
7.39 [m, 2H, bipy], 6.75 [m, 4H, Ph], 6.39 [m, 4H, Ph], 6.22
[m, 2H, Ph]. 13C{1H} NMR (CD2Cl2): 200.02 [2CO], 193.22
[CO], 157.00 [Ph], 155.96, 153.39, and 138.99 [bipy], 128.85
[Ph], 127.04 [bipy], 123.25 [Ph], 123.07 [bipy], 116.52 [Ph].
Anal. Calcd for C25H18N3O3Re: C, 50.49; H, 3.05; N, 7.06.
Found: C, 50.13; H, 3.29; N, 7.17.
Rea ction of 4a w ith Dip h en ylp h osp h in e. HPPh2 (10
mL, 0.057 mmol) was added to a solution of 4a (0.034 g, 0.056
mmol) in THF (10 mL), and the mixture was stirred for 30
min at room temperature. The color of the solution changed
from green to dark blue. The solvent was removed under
vacuum, and the solid was washed with hexane (5 mL) to
afford 10a , dark blue. Yield: 0.023 g, 67%. IR (THF): 2001,
1
1898. H NMR (C6D6): 8.35 [m, 2H, bipy] 7.48 [m, 4H, bipy],
7.15-6.05 [m, 12H, 2H bipy and 10H, 2 Ph,]. 31P NMR(C6D6):
-43.09. Anal. Calcd for C25H18N2O3PRe: C, 49.09; H, 2.96; N,
4.58. Found: C, 49.50; H, 2.41; N, 4.60.
Rea ction of 4b w ith Dip h en ylp h osp h in e. The procedure
was as described for 10a , using 4b (0.030 g, 0.053 mmol) and
HPPh2 (10 µL, 0.057 mmol). Subsequent workup afforded 10b
as a dark blue powder. Slow diffusion of hexanes into a solution
of 10b in THF at room temperature afforded dark blue
crystals, one of which was suitable for an X-ray analysis.
1
Yield: 0.025 g, 72%. IR (THF): 2002, 1898. H NMR (C6D6):
8.60 [m, 2H, bipy] 7.39 [m, 4H, bipy], 7.33-6.73 [m, 12H, 2H
bipy and 10H, 2 Ph]. 31P NMR (C6D6): -42.21. Anal. Calcd for
C
27H18N2O3PRe: C, 51.09; H, 2.85; N,4.40. Found: C, 51.21;
H, 2.71; N, 4.15.
Rea ction of 10a w ith MeI. MeI (3.0 µL, 0.049 mmol) was
added to a solution of [Re(PPh2)(CO)3(bipy)] (10a ) (0.030 g,
0.049 mmol) in THF (10 mL) cooled at -70 °C. The mixture
was allowed to warm to room temperature. The color of the
solution changed from dark blue to orange. Volatiles were
removed to afford [Re(PMePh2)(CO)3(bipy)]I (11-I). Yield:
1
0.022 g, 60%. IR (THF): 2039, 1954, 1924. H NMR (CD2Cl2):
8.82, 8.66, and 8.22 [m, 2H each, bipy], 7.53-7.10 [m, 12H,
2H bipy and 10H, 2 Ph,], 1.60 [d(7.9 Hz), 3H, PPh2Me]. 31P
NMR (C6D6): 1.02. Anal. Calcd for C26H21IN2O3PRe: C, 41.44;
H, 2.80; N, 3.71. Found: C, 41.26; H, 2.67; N, 3.85.
[Re(NpTol2)(CO)3(bip y)] (7). As described for 6, 7 was
obtained using [Re(OTf)(CO)3(bipy)] (1a ) (0.050 g, 0.086 mmol),
NHpTol2 (0.018 g, 0.094 mmol), and KN(SiMe3)2 (0.188 mL of
a solution 0.5 M in toluene, 0.094 mmol). Yield: 0.045 g, 79%,
green. IR (THF): 2007, 1902, 1887. 1H NMR (CD2Cl2): 8.81
[m, 2H, bipy], 7.89 [m, 4H, bipy], 7.32 [m, 2H, bipy], 6.55, 6.53,
6.10, and 6.08 [AA′BB′, 8H, pTol], 2.06 [s, 6H, CH3, p-Tol].
Anal. Calcd for C27H22N3O3Re: C, 52.07; H, 3.56; N, 6.74.
Found: C, 52.13; H, 3.49; N, 6.47.
Rea ction of 10a w ith MeOTf. MeOTf (5.5 µL, 0.049 mmol)
was added to a solution of [Re(PPh2)(CO)3(bipy)] (10a ) (0.030
g, 0.049 mmol) in THF (10 mL) cooled at -70 °C. The color of
the solution changed instantaneously from dark blue to orange.
Volatiles were removed to afford [Re(PMePh2)(CO)3(bipy)]OTf
(11-OTf). Yield: 0.025 g, 77%. IR (THF): 2039, 1954, 1924.
1H NMR (CD2Cl2): 8.67, 8.48, and 8.16 [m, 2H each, bipy],
7.48-7.05 [m, 12H, 2H bipy and 10H, 2Ph,], 1.57 [d (7.9 Hz),
3H, PPh2Me]. 31P NMR (CD2Cl2): 1.28. 19F NMR (CD2Cl2):
-78.75. Anal. Calcd for C27H21F3N2O6PReS: C, 41.08; H, 2.72;
N, 3.61. Found: C, 41.25; H, 2.38; N, 3.68.
Rea ction of 4a w ith 4-Eth lyp h en ol. 4-Ethylphenol (0.008
g, 0.067 mmol) was added to a solution of [Re(NHp-Tol)(CO)3-
(bipy)] (4a ) (0.034 g, 0.056 mmol) in THF (10 mL). The mixture
was stirred for 3 h at room temperature. The color of the
solution changed from green to orange. The solvent was
removed under reduced pressure, and the orange solid was
washed with Et2O (5 mL) to afford 8. Yield: 0.022 g, 71%. IR
Rea ction of 6 w ith MeOTf. A 5 mm NMR tube was
charged with a solution of [Re(NPh2)(CO)3(bipy)] (6) (20 g,
0.034 mmol) in CD2Cl2 (0.5 mL), capped with a rubber septum,
and cooled to -70 °C. MeOTf (3.8 µL, 0.034 mmol) was
1
1
(THF): 2003, 1899, 1884. H NMR (CD2Cl2): 8.97, 8.22, 8.05,
injected, and the reaction was monitored by H NMR. After 2
and 7.51 [m, 2H each, bipy], 6.73, 6.69, 6.20, and 617 [AA′BB′,
h at room temperature the color of the solution changed from

1974 Organometallics, Vol. 21, No. 9, 2002
Hevia et al.
green to yellow, and the 1H NMR showed the signals of [Re-
(OTf)(CO)3(bipy)] (1a ) and free NMePh2.
Brent Gunnoe for disclosing his results prior to publica-
tion.
Su p p or tin g In for m a tion Ava ila ble: 1H NMR spectra at
variable temperature and tables giving positional and thermal
parameters, bond distances, and bond angles for 2a , 5, 6, and
10b. This material is available free of charge via the Internet
at http://pubs.acs.org.
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.), Dr. Luc´ıa Riera and Dr. Marta E. Gonza´lez-
Mosquera for help with online searches, and Dr. T.
OM0110383