Acyclic diamino carbene complexes of manganese(I): Synthesis, deprotonation, and subsequent Multiple insertion reaction of alkynes

Article abstract of DOI:10.1021/om800888r

The cationic isocyanide complexes fac-[Mn(CNR)(CO)₃(bipy)] ⁺ (1) react with NH₂CH₃ to give acyclic diaminocarbene (ADC) complexes fac-[Mn(ADC)(CO)₃(bipy)]⁺ (2), which when treated with KOH

Full text of DOI:10.1021/om800888r

830
Organometallics 2009, 28, 830–836
Acyclic Diamino Carbene Complexes of Manganese(I): Synthesis,
Deprotonation, and Subsequent Multiple Insertion Reaction of
Alkynes
Javier Ruiz* and Bernabe´ F. Perandones
Departamento de Qu´ımica Orga´nica e Inorga´nica, Facultad de Qu´ımica, UniVersidad de OViedo,
33006 OViedo, Spain
ReceiVed September 12, 2008
The cationic isocyanide complexes fac-[Mn(CNR)(CO)3(bipy)]+ (1) react with NH2CH3 to give acyclic
diaminocarbene (ADC) complexes fac-[Mn(ADC)(CO)3(bipy)]+ (2), which when treated with KOH yield
neutral formamidinyl (ADC-H) derivates fac-[Mn(ADC-H)(CO)3(bipy)] (3). These undergo multiple
insertion reactions of methyl propiolate or phenyl acetylene into the metal-carbon bond to afford
compounds 4 and 5 containing a new η4-azacyclohexadienyl ligand, with the loss of the bipy chelating
ligand.
ADC complexes containing N-H residues can be easily
deprotonated to afford formamidinyl derivatives9 and on occa-
sion liberated from the metal center yielding the corresponding
formamidines,2a,9b which have also been obtained upon reductive
elimination from hydrido formamidinyl Pt(II) derivatives.9b
ADC complexes appear also to be involved in the catalytic
formation of carbodiimides from isocyanides and amines on gold
metal surfaces.10 Apart from the above, the reactivity of ADC
complexes or their deprotonated forms remains practically
unexplored.
In this context, we describe herein the synthesis of cationic
ADC complexes of manganese(I) of general formula fac-
[Mn(ADC)(CO)3(bipy)]+ by 1,2-addition of NH2Me to a variety
of coordinated arylisocyanide ligands, their deprotonation reac-
tion yielding formamidinyl derivatives, and the subsequent
multiple insertion reaction of methyl propiolate and phenyl
acetylene into the metal-carbon bond to afford a new type of
azacyclohexadienyl ligand.
Introduction
The chemistry of N-heterocyclic carbene (NHC) metal
complexes has received widespread interest in recent years
mainly owing to its application in homogeneous catalysis.1 Less
attention has been paid to their analogous acyclic diaminocar-
bene (ADC) complexes, although this type of derivative has
been known for more than four decades.2 However, isolation
of free ADCs3 and recent recognition that ADC palladium
complexes have activities comparable to those of NHCs in some
catalytic processes4 have furnished a new impetus to the field.
Methods for synthesizing ADC complexes involve nucleophilic
addition of primary or secondary amines to coordinated
isocyanides2,5 or reaction of free ADC with the appropriate
metallic fragment.3,6 Specific routes implying deprotonation of
tetrazolium ions with carbonylferrate7 and reaction of tetram-
ethylformamidinium dichloride with Fe2(CO)98 have also been
described.
Results and Discussion
* To whom correspondence should be addressed. E-mail: jruiz@
fq.uniovi.es.
When dichloromethane solutions of the cationic isocyanide
complexes fac-[Mn(CNR)(CO)3(bipy)]+ (1a, R ) phenyl; 1b,
R ) 2-naphthyl; 1c, R ) xylyl; 1d, R ) 2-chloro-6-methylphe-
nyl) are treated with an excess of gaseous methylamine at room
temperature, the acyclic diaminocarbene complexes fac-
[Mn{(C(NHR)NHMe}(CO)3(bipy)]+ (2a-d) are formed within
a few minutes (Scheme 1). The reaction was monitored by IR
spectroscopy showing the disappearance of the νCN band of the
coordinated isocyanide ligand (2171-2176 cm-1) together with
the νCO bands of the carbonyl ligands appearing at lower
frequencies than those in the parent compounds (about 30 cm-1
on average, see Table 1). The IR spectra of these derivatives in
KBr also reveal the presence of νN-H bands in the range
3300-3400 cm-1, as well as a νC-N band around 1530 cm-1
characteristic of diaminocarbene ligands.
(1) (a) Arduengo, A. J., III. Acc. Chem. Res. 1999, 32, 913. (b)
Bourissou, D.; Guerret, O.; Gabba¨ı, F. P.; Bertrand, G. Chem. ReV. 2000,
100, 39. (c) Herrmann, W. A. Angew. Chem., Int. Ed. 2002, 41, 1290. (d)
Crabtree, R. H. Coord. Chem. ReV. 2007, 251 (2), 595.
(2) (a) Crociani, B. In Reactions of Coordinated Ligands; Braterman,
P. S., Ed.; Plenum Press: New York, 1986; pp 553-638. (b) Singleton, E.;
Oosthuizen, H. E. AdV. Organomet. Chem. 1983, 22, 209. (c) Michelin,
R. A.; Pombeiro, A. J. L.; Guedes da Silva, M. F. C. Coord. Chem. ReV.
2001, 218, 75.
(3) (a) Alder, R. W.; Allen, P. R.; Murray, M.; Orpen, A. G. Angew.
Chem., Int. Ed. Engl. 1996, 35, 1121. (b) Rosen, E. L.; Sanderson, M. D.;
Saravanakumar, S.; Bielawski, C. W. Organometallics 2007, 26, 5774.
(4) (a) Wanniarachchi, Y. A.; Kogiso, Y.; Slaughter, L. M. Organome-
tallics 2008, 27, 21. (b) Moncada, A. I.; Khan, M. A.; Slaughter, L. M.
Tetrahedron Lett. 2005, 46, 1399. (c) Moncada, A. I.; Manne, S.; Tanski,
J. M.; Slaughter, L. M. Organometallics 2006, 25, 491. (d) Kremzow, D.;
Seidel, G.; Lehmann, C. W.; Fu¨rstner, A. Chem.sEur. J. 2005, 11, 1833.
(e) Dhudshia, B.; Thadani, A. N. Chem. Commun. 2006, 668.
(5) (a) Wanniarachchi, Y. A.; Slaughter, L. M. Chem. Commun. 2007,
3294. (b) Wanniarachchi, Y. A.; Slaughter, L. M. Organometallics 2008,
27, 1055, and references therein.
¨
(6) (a) Herrmann, W. A.; Ofele, K.; Preysing, D. V.; Herdtweck, E. J.
(9) (a) Riera, V.; Ruiz, J. J. Organomet. Chem. 1990, 384, 339. (b)
Michelin, R. A.; Bertani, R.; Mozzon, M.; Zanotto, L. Organometallics
1990, 9, 1449. (c) Crociani, B.; Bianca, F. D.; Fontana, A.; Forsellini, E.;
Bombieri, G. J. Chem. Soc., Dalton Trans. 1994, 407.
Organomet. Chem. 2003, 684, 235. (b) Frey, G. D.; Herdtweck, E.;
Herrmann, W. A. J. Organomet. Chem. 2006, 691, 2465.
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(7) Mu¨ller, J.; Ofele, K.; Krebs, G. J. Organomet. Chem. 1974, 82, 383.
(8) Petz, W. Angew. Chem., Int. Ed. Engl. 1975, 14, 367.
(10) Angelici, R. J. J. Organomet. Chem. 2008, 693, 847.
10.1021/om800888r CCC: $40.75
2009 American Chemical Society
Publication on Web 01/09/2009

Acyclic Diamino Carbene Complexes of Manganese(I)
Organometallics, Vol. 28, No. 3, 2009 831
Scheme 1. Synthesis of the Manganese Diaminocarbene
neutral formamidinyl complexes 3a-d (Scheme 2) in quantita-
tive yields, a process that is accompanied by a strong color
change from yellow to red. The two step synthesis of forma-
midinyl complexes by reaction of coordinated isocyanides with
amines and subsequent deprotonation reaction is well-known
in the literature,9 although these derivatives can also be obtained
by direct insertion of isocyanides in the metal-nitrogen bond
of amido complexes.14
a
Complexes 2a-d
Deprotonation of 2a-d to afford 3a-d occurs in the N(H)aryl
group rather than in the N(H)Me residue, due to the more acidic
character of the former. This is corroborated by the maintenance
of the doublet signal of the methyl group in the 1H NMR spectra
of compounds 3 (Table 2) (in the case of 3a,b a broad singlet
is observed), as well as by the presence of the N(H)Me fragment
in the insertion product with alkyne molecules, as we will
comment below. Naturally, the IR spectra of 3a-d in the ν(CO)
region show the characteristic pattern of a fac-geometry, but at
lower frequencies (30 cm-1 on average, Table 1) than the parent
complexes 2a-d.
The deprotonation reaction of 2a-d proved to be fully
reversible, so the addition of an equivalent of HBF4 to 3a-d
gives the acyclic diaminocarbene complexes again. In fact, this
reversible process is useful in the purification of compounds
2a,b (see Experimental Section).
In view of the lack of precedents in the literature, we found
it interesting to begin the study of the reactivity of ADC and
formamidinyl complexes toward unsaturated molecules such as
alkynes. It must be pointed out that a rare case of migratory
insertion of alkynes in NHC complexes of ruthenium(II) has
been described.15 In our case, the ADC carbene complexes
2a-d do not react with a variety of alkynes such as dimethyl
acetylenedicarboxylate (DMAD), methyl propiolate, or phenyl
acetylene, even under forcing conditions, whereas the depro-
tonated derivatives 3a-d readily react with those alkynes. In
the case of methyl propiolate and phenyl acetylene, the reaction
is selective and affords the multiple insertion products 4a-d,
and 5a-c, respectively, as we will discuss in subsequent lines.
For the alkyne DMAD, the reaction is not selective giving a
complex and untreatable mixture of species.
The heating of compounds 3 with 2 equiv of methyl
propiolate in toluene at 60 °C for 15 min or with 4 equiv of
phenyl acetylene in toluene at 90 °C for 20 min gave rise to
the formation of complexes 4 and 5, respectively (Scheme 3),
involving liberation of the bipy ligand. Chromatography on
grade IV acidic alumina and elution with 1/3 dichloromethane/
hexane removed the bipy from the mixture, while elution with
1/1 dichloromethane/hexane gave a yellow band of 4a-d or
5a-c, which were isolated as yellow solids. A plausible
mechanism for the formation of these complexes is shown in
Scheme 3. Thus, two successive insertion reactions of the alkyne
into the carbon-metal bond of the formamidinyl ligand16 in a
head-to-tail fashion give rise to the alkenyl intermediates I and
II. The last undergoes electrocyclic rearrangement yielding
complex III, forming a new azacyclohexadienyl ligand acting
in an η1 manner. The additional donor capability of the cyclic
a
2a, R ) phenyl; 2b, R ) 2-napthyl; 2c, R ) xylyl; 2d, R )
2-chloro-6-phenyl.
The multiple-bond character of the two Ccarbene-N bonds
causes restricted rotation around these bonds;2a consequently
four conformers may result depending upon the relative disposi-
tion of the substituents on the nitrogen atoms (Figure 1). The
1H NMR spectra (Table 1 and experimental section) show the
presence of two isomers in the case of 2a,b and just one isomer
in the case of 2c,d. Thus, a doublet signal is observed for the
NMe group around 3.1 ppm for complexes 2c,d, whereas two
doublets at about 3.1 and 2.7 ppm are present in the case of
complexes 2a,b. Owing to steric reasons, the two amphi
configurations ZE and EZ (forms a and b in Figure 1) appear to
be clearly favored2a and should be those formed in complexes
2a,b. The bulkier xylyl and 2-chloro-6-methylphenyl substituents
in complexes 2c,d cause strong steric hinderance so that one of
these two conformers appears to be largely preferred. An X-ray
diffraction study carried out on 2d (Figure 2) shows that this
complex displays a diaminocarbene conformation corresponding
to that of form a in Figure 1, that is with the bulky 2-chloro-
6-methylphenyl group located in a syn disposition with respect
to the metallic fragment and anti with respect to the N(H)Me
group. The preference of form a could be tentatively explained
taking into account the longer value of the Mn-Ccarbene bond
distance (2.097(2) Å) compared with the Ccarbene-N(H)Me bond
length (1.330(3) Å), which would allow a smaller steric
repulsion between the 2-chloro-6-methylphenyl substituent and
the metallic fragment than would exist between this group and
the N(H)Me residue in the isomeric form b. Among the other
structural parameters of 2d, it is worth noting the C1-N1
(1.339(3) Å) and C1-N2 (1.330(3) Å) bond lengths, which are
intermediate between single and double bond, thus justifying
the absence of free rotation around those bonds in the ADC
complexes 2a-d. On the other hand, the Mn-Ccarbene (2.097(2)
Å) distance in 2d is appreciably longer than that found
(2.054-2.078(3) Å) in similar N-heterocyclic carbene com-
plexes of formula fac-[Mn(NHC)(CO)3(bipy)]+, recently pre-
pared by our group.11,12 These structural data, together with the
fact that in the IR spectra the νCO bands for compounds 2a-d
appear at slightly higher frequencies than those for the analogous
NHC compounds (3 cm-1 on average, see Table 1 and refs 11
and 12), seem to indicate that the ADC ligands described herein
have slightly weaker basicities than their NHC counterparts,
contrary to what is found in the literature for other ADC
ligands.13
Complexes 2a-d are instantaneously deprotonated when
(14) Benetollo, F.; Carta, G.; Cavinato, G.; Crociani, L.; Paolucci, G.;
Rossetto, G.; Veronese, F.; Zanella, P. Organometallics 2003, 22, 3985.
(15) (a) Becker, E.; Stingl, V.; Dazinger, G.; Mereiter, K.; Kirchner, K.
Organometallics 2007, 26, 1531. (b) Becker, E.; Stingl, V.; Dazinger, G.;
Puchberger, M.; Mereiter, K.; Kirchner, K. J. Am. Chem. Soc. 2006, 128,
6572.
(16) In order to allow coordination of the alkyne molecule previous to
each insertion process, a reversible change in the coordination mode of the
bipy ligand from bidentade to monodentade could be proposed. See, for
instance: Memering, M. N.; Dobson, G. R. Inorg. Chem. 1973, 12, 2490.
treated with an excess of KOH in dichloromethane to give the
(11) Ruiz, J.; Perandones, B. F.; Garc´ıa, G.; Mosquera, M. E. G.
Organometallics 2007, 26, 5687.
(12) Ruiz, J.; Perandones, B. F. J. Am. Chem. Soc. 2007, 129, 9298.
(13) (a) Denk, K.; Sirsch, P.; Herrmann, W. A. J. Organomet. Chem.
2002, 649, 219. (b) Lee, M.-T.; Hu, C.-H. Organometallics 2004, 23, 976.
(c) Magill, A. M.; Cavell, K. J.; Yates, B. F. J. Am. Chem. Soc. 2004, 126,
8717.

832 Organometallics, Vol. 28, No. 3, 2009
Ruiz and Perandones
1
Table 1. Selected Spectroscopic Data (IR and H NMR) for Compounds 1-5
compound
IR (CH2Cl2, cm-1), ν(CO)a
1H NMR,b
δ
1a
1b
1c
1d
2a
2050vs, 1990s, 1957vs; 2175w ν(CN)
2050vs, 1990s, 1957vs; 2176w ν(CN)
2050vs, 1989s, 1957vs; 2171w ν(CN)
2051vs, 1993s, 1959vs; 2171w ν(CN)
2031vs, 1949s, 1924s
3
Isomer A: 6.57 (2H, br s, NH); 3.08 (3H, d, JHH ) 5.4, NCH3). Isomer
3
B: 6.41 (2H, br s, NH); 2.68 (3H, d, JHH ) 5.4, NCH3)
3
2b
2031vs, 1948s, 1924s
Isomer A: 6.72 (2H, br s, NH); 3.09 (3H, d, JHH ) 4.8, NCH3). Isomer
3
B: 6.59 (2H, br s, NH); 2.75 (3H, d, JHH ) 4.8, NCH3)
3
2c
2d
3a
3b
3c
3d
4a
4b
4c
4d
5a
5b
5c
2033vs, 1952s, 1924s
2033vs, 1953s, 1924s
2001vs, 1912s, 1892s
2001vs, 1912s, 1892s
2000vs, 1906s, 1891s
2002vs, 1910s, 1893s
2004 vs, 1926s, 1910s
2004vs, 1926s, 1911s
2002vs, 1923s, 1908s
2003vs, 1924s, 1909s
1982vs, 1896s, 1886sh
1982vs, 1897s, 1885sh
1979vs, 1890s, 1881sh
6.22 (1H, s, NH); 6.17 (1H, s, NH); 3.14 (3H, d, JHH ) 5.0, NCH3)
3
6.28 (1H, s, NH); 6.13 (1H, s, NH); 3.21 (3H, d, JHH ) 5.1, NCH3)
4.43 (1H, s, NH); 2.52 (3H, br s, NCH3)
4.62 (1H, s, NH); 2.62 (3H, br s, NCH3)
3
3
4.42 (1H, d,, JHH ) 4.0, NH); 2.61 (3H, d, JHH ) 4.0, NCH3)
3
4.48 (1H, s, NH); 2.54 (3H, d, JHH ) 4.4, NCH3)
3
5.21 (1H, s, NH); 2.93 (3H, d, JHH ) 2.5, NCH3)
3
5.30 (1H, s, NH); 2.92 (3H, d, JHH ) 4.8, NHCH3)
4.75 (1H, s, NH); 2.93 (3H, br s, NCH3)
3
4.72 (1H, s, NH); 2.96 (3H, d, JHH ) 5.1, NCH3)
3
5.18 (1H, s, NH); 3.03 (3H, d, JHH ) 3.0, NCH3)
3
5.28 (1H, s, NH); 3.00 (3H, d, JHH ) 3.1, NCH3)
4.55 (1H, s, NH); 3.06 (3H, br s, NCH3)
a Abbreviations: vs ) very strong, s ) strong, w) weak, sh ) shoulder. b NMR spectra recorded in CD2Cl2.
Scheme 2.
Reversible Deprotonation Reaction of
Compounds 2a-d
Figure 1. Schematic representation of the four possible isomers
for carbene complexes 2a-d.
5c, Figures 3 and 4, respectively). The IR spectra in the νCO
region show typical fac-tricarbonyl patterns; the relative low
frequencies of the νCO bands showing a high donor ability of
the cyclic ligand, specially in the case of 5a-c, lacking electron-
withdrawing carboxylate groups. The NMR and X-ray data of
4 and 5 suggest that these complexes are better considered as
containing within the azaheterocycle a butenediyl fragment η4-
coordinated to Mn(+1) (form b in Figure 5) rather than a
butadiene fragment η4-coordinated to Mn(-1) (form a in Figure
5). This is evidenced by the strong difference in the chemical
shift of the two C-H protons in the azaheterocycle, one of them
being close to vinylic in character (range 6.4-6.9 ppm), whereas
the other one appears at much lower frequency (at about 3 ppm),
as a consequence of its alkylic (carbanionic) character. A similar
behavior is observed in the 13C{1H} NMR chemical shifts of
the corresponding C-H carbon atoms, appearing at about 80
(vinylic) and 30 (carbanionic) ppm, respectively (see Experi-
mental Section). The single-crystal X-ray diffraction study
carried out on complexes 4d (Figure 3) and 5c (Figure 4)
showed that both compounds have very similar structures,
forming the same regioisomer of the azacyclohexadienyl ligand.
The four carbon atoms of the cycle directly bonded to
manganese arise from two alkyne molecules, which are coupled
in a head-to-tail mode. The azaheterocycle is completed with
the imine residue of the original formamidinyl ligand. The
azaheterocycle is bent, with dihedral angles between C1-
C2-C3-C4 and C4-C5-N1-C1 planes of 43.7(5)° (4d) and
44.4(2)° (5c). The C1-C2 (1.438(5) Å (4d), 1.446(2) Å (5c))
and C3-C4 (1.454(5) Å (4d), 1.469(2) Å (5c)) distances are
appreciable longer than the C2-C3 distances (1.395(2) Å (4d),
1.403(2) Å (5c)), supporting the butenediyl description of the
four carbon atom segment bonded to manganese (form b, Figure
5). In agreement with this consideration, the Mn1-C2 and
Mn1-C3 bond lengths are slightly shorter than the Mn1-C1
Figure 2. Molecular structure of 2d (50% thermal ellipsoids)
showing only one of the two positions adopted by disordered Cl
and CH3 substituents in the 2-chloro-6-methylphenyl group. Selected
interatomic distances (Å) and angles (deg): Mn1-C1 ) 2.097(2),
C1-N1 ) 1.339(3), C1-N2 ) 1.330(3), N1-C2 ) 1.428(3),
N2-C3 ) 1.466(3); Mn1-C1-N1 ) 129.0(2), Mn1-C1-N2 )
118.1 (2), N1-C1-N2 ) 112.9(2), C1-N1-C2 ) 128.6(2),
C1-N2-C3 ) 126.4(2).
ligand forces substitution of bipy affording complexes 4 and 5,
which contain the azaheterocycle η4-coordinated to the metal
center. It must be noted that related η4-azacyclohexadienyl
complexes have recently been described resulting from the
coupling of alkynes to iminoacyl ligands on manganese.17
The structure of these complexes 4 and 5 depicted in Scheme
3 was determined by spectroscopic methods (Table 1 and
Experimental Section) and by X-ray diffraction analysis (4d and
(17) Homrighausen, C. L.; Alexander, J. J.; Krause Bauer, J. A. Inorg.
Chim. Acta 2002, 334, 419.

Acyclic Diamino Carbene Complexes of Manganese(I)
Organometallics, Vol. 28, No. 3, 2009 833
Table 2. Crystallographic Data for 2d, 4d, and 5c
2d
4d
5c
formula
FW
C22H19Cl2MnN4O7
577.25
C20H18ClMnN2O7 · CH2Cl2
573.68
C29H25MnN2O3 · 0.5CH2Cl2
546.92
color/habit
yellow/prism
0.17 × 0.14 × 0.08
monoclinic
P21/c
9.76710(10)
12.0128(2)
20.2660(3)
95.4160(10)
2367.20(6)
4
yellow/prism
0.25 × 0.20 × 0.04
monoclinic
P21/c
12.376(2)
11.822(2)
16.339(3)
94.657(3)
2382.6(7)
4
yellow/prism
0.58 × 0.42 × 0.17
monoclinic
P21/n
14.7044(6)
10.3457(3)
17.4489(7)
105.016(2)
2563.81(16)
4
cryst dimensions (mm3)
cryst syst
space group
a, Å
b, Å
c, Å
ꢀ, deg
V, Å3
Z
T, K
100(2)
1.62
0.836
1176
110(2)
1.599
0.936
1168
100(2)
1.417
0.654
1132
Dcalcd, g cm-3
µ, mm-1
F(000)
θ range, deg
no. of rflns collected
no. indep reflns/Rint
no. of obsd reflns (I > 2σ(I))
no. data/restraints/params
R1/wR2 (I > 2 σ(I))a
R1/wR2 (all data)a
GOF (on F2)a
1.97-26.43
1.65-26.45
1.62 - 27.88
36093
20548
44778
4864/0.0505
3866
4864/0/337
0.0363/0.0785
0.0519/0.0829
1.030
4902/0.0712
3208
4902/1/328
0.0516/0.1203
0.0878/0.1322
1.088
6116/0.0339
4990
6116/0/358
0.0366/0.0847
0.0498/0.0908
1.052
largest diff peak/hole (e Å-3
)
+0.458/-0.456
+0.704/-0.778
+0.421/-0.369
a
2
2
2
R1 ) ∑(||Fo| - |Fc||)/∑|Fo|; wR2 ) {∑[w(Fo - Fc2)2]/∑[w(Fo )2]}1/2; GOF ) {∑[w(Fo - Fc2)2]/(n - p)}1/2
.
Scheme 3. Proposed Mechanism for the Formation of
Compounds 4a-d and 5a-ca
Figure 3. Molecular structure of 4d (50% thermal ellipsoids)
showing only one of the two positions adopted by disordered Cl
and CH3 substituents in the 2-chloro-6-methylphenyl group. Selected
interatomic distances (Å) and angles (deg): Mn1-C1 ) 2.124(3),
Mn1-C2 ) 2.075(4), Mn1-C3 ) 2.065(4), Mn1-C4 ) 2.125(4),
Mn1-C5 ) 2.934(5), C1-C2 ) 1.438(5), C2-C3 ) 1.395(5),
C3-C4 ) 1.454(5), C4-C5 ) 1.437(5), C5-N1 ) 1.344(4),
C5-N2 ) 1.329(4), C1-N1 ) 1.474(4); C1-C2-C3 ) 113.0(3),
C2-C3-C4 ) 115.2 (3), C3-C4-C5 ) 114.6(3), C4-C5-N1
) 115.7(3), C5-N1-C1 ) 114.4(3), N1-C1-C2 ) 115.8(3).
a
4a, R ) phenyl, R′ ) CO2CH3; 4b, R ) 2-napthyl, R′ ) CO2CH3;
4c, R ) xylyl, R′ ) CO2CH3; 4d, R ) 2-chloro-6-methyl, R′ )
CO2CH3; 5a, R ) R′ ) phenyl; 5b, R ) 2-napthyl, R′ ) phenyl; 5c,
R ) xylyl, R′ ) phenyl.
and Mn1-C4 ones in these complexes (see Figures 3 and 4).
Also of note is the short N1-C5 bond length (1.344(4) and
1.335(2) Å for 4d and 5c, respectively), showing its multiple
bond character.
containing a butenediyl framework within the heterocycle.
Works aiming to insert other unsaturated molecules into the
metal-carbon bond of the formamidinyl derivatives are cur-
rently in progress in our group.
Conclusion
We have described herein the synthesis of acyclic diamino
carbene (ADC) complexes of manganese(I) by reaction of
NH2Me with a variety of coordinated isocyanide ligands. In
these complexes, the carbene ligands are easily deprotonated
affording the corresponding formamidinyl derivatives, which
undergo regiospecific multiple insertion reactions of alkynes into
the metal-carbon bond to form azacyclohexadienyl ligands η4-
coordinated to the metal center. Spectroscopic and structural
data suggest that these cyclic ligands can be considered as
Experimental Section
General Remarks. All reactions and manipulations were carried
out under a nitrogen atmosphere using standard Schlenk techniques.
Solvents were distilled over appropriate drying agents under dry
nitrogen prior to use. Compounds fac-[Mn(CO)3(CNR)(bipy)][ClO4]

834 Organometallics, Vol. 28, No. 3, 2009
Ruiz and Perandones
solution was concentrated to 3 mL, and hexane (10 mL) was added
to afford a yellow solid, which was dried under vacuum. Yield:
0.083 g (70%). Anal. (%) Calcd for C21H18BF4MnN4O3: C 48.87,
H 3.52, N 10.85. Found: C 48.70, H 3.36, N 10.51. IR (CH2Cl2):
ν 2031 (vs), 1949 (s), 1924 (s) cm-1 (CO). IR (KBr): ν 3438 (w),
1
3306 (w) cm-1 (NH); 1536 (s) cm-1 (CN). H NMR (300 MHz,
3
CD2Cl2), Isomer A (25%): δ 9.16 (2H, d, JHH ) 5.4, Ha bipy),
8.50 (2H, d, 3JHH ) 8.1, Hd bipy), 8.22 (2H, td, 4JHH ) 1.2, 3JHH
)
7.9, Hc bipy), 7.78-7.72 (2H, m, Hb bipy), 7.36-7.29 (3H, m, Ph),
3
6.69 (2H, d, JHH ) 7.2, Horto Ph), 6.57 (2H, br s, NH), 3.08 (3H,
d, 3JHH ) 5.4, NCH3). Isomer B (75%): δ 8.73 (2H, d, 3JHH ) 5.4,
3
Ha bipy), 8.28 (2H, d, JHH ) 8.1, Hd bipy), 8.07 (2H, td,4JHH
)
3
3
1.2, JHH ) 7.9, Hc bipy), 7.47 (2H, t, JHH ) 7.3, Hb bipy),
3
7.36-7.29 (3H, m, Ph), 6.99 (2H, d, JHH ) 7.2, Horto Ph), 6.41
(2H, br s, NH), 2.68 (3H, d,3JHH ) 5.4, NCH3).
[Mn{C(NHC10H7)(NHCH3)}(CO)3(bipy)][BF4] (2b · BF4). The
procedure is analogous to that described above, using 1b · ClO4 (0.1
g, 0.18 mmol), NH2CH3 (bubbled through the solution for 10 min),
KOH (0.25 g, 4.46 mmol), and HBF4 (0.028 mL, 54% w, 0.20
Figure 4. Molecular structure of 5c (50% thermal ellipsoids).
Selected interatomic distances (Å) and angles (deg): Mn1-C1 )
2.1101(16), Mn1-C2 ) 2.0852(16), Mn1-C3 ) 2.0849(16),
Mn1-C4 ) 2.1332(17), Mn1-C5 ) 2.9380(20), C1-C2 )
1.446(2), C2-C3 ) 1.403(2), C3-C4 ) 1.469(2), C4-C5 )
1.446(2), C5-N1 ) 1.335(2), C5-N2 ) 1.330(2), C1-N1 )
1.490(2); C1-C2-C3 ) 114.57(15), C2-C3-C4 ) 113.14(14),
C3-C4-C5 ) 115.56(14), C4-C5-N1 ) 115.95(15), C5-N1-C1
) 114.34(13), N1-C1-C2 ) 114.04(14).
mmol). Yield: 0.077
g
(75%). Anal. (%) Calcd for
C25H20BF4MnN4O3: C 53.03, H 3.56, N 9.90. Found: C 52.99, H
3.65, N 9.98. IR (CH2Cl2): ν 2031 (vs), 1948 (s), 1924 (s) cm-1
(CO). IR (KBr): ν 3439 (w), 3325(w) cm-1 (NH); 1538 (s) cm-1
(CN). 1H NMR (300 MHz, CD2Cl2), Isomer A (25%): δ 9.20 (2H,
3
3
d, JHH ) 4.9, Ha bipy), 8.53 (2H, d, JHH ) 8.0, Hd bipy),
8.01-7.04 (11H, m, Harom C10H7, Hc and Hb bipy), 6.72 (2H, br s,
NH), 3.09 (3H, d, JHH ) 4.8, NCH3). Isomer B (75%): δ 8.61
3
3
3
(2H, d, JHH ) 4.9, Ha bipy), 8.24 (2H, d, JHH ) 8.0, Hd bipy),
8.01-7.04 (11H, m, Harom C10H7, Hc and Hb bipy), 6.59 (2H, br s,
NH), 2.75 (3H, d, JHH ) 4.8, NCH3).13C NMR (75.5 MHz,
3
CD2Cl2), Isomer A (25%): δ 219.4 (s, Ccarbene), 216.5, 213.1 (br s,
CO), 158.8 (s, C1 bipy), 154.6 (s, C2 bipy), 140.1-121.4 (C3, C4,
C5 bipy, CHarom naphtyl), 34.7 (NCH3). Isomer B (75%): δ 220.5
(s, Ccarbene); 217.0, 213.1 (br s, CO); 155.5 (s, C1 bipy), 153.7 (s,
C2 bipy), 140.1-121.4 (C3, C4, C5 bipy, CHarom naphtyl), 30.9
(NCH3).
Figure 5. Two extreme representations of the bond between
manganese and the η4-azacyclohexadienyl ligand in the complexes
4 and 5.
[Mn{C(NHXylyl)(NHCH3)}(CO)3(bipy)][ClO4] (2c · ClO4). Thr-
ough a solution of 1c · ClO4 (0.1 g, 0.19 mmol) in CH2Cl2 (10 mL),
NH2CH3 was bubbled for 20 min. The solvent was then evaporated
to dryness, and the remaining mixture was stirred with 10 mL of
CH2Cl2. The resulting suspension was filtered with kieselgur
affording a yellow solution, which was concentrated to 4 mL.
Addition of 10 mL of hexane with vigorous stirring gave a yellow
solid, which was filtered off and dried under vacuum. Yield: 0.075
g (71%). Anal. (%) Calcd for C23H22ClMnN4O7: C 49.61, H 3.98,
N 10.06. Found: C 49.61, H 4.02, N 9.92. IR (CH2Cl2): ν 2033
(vs), 1952 (s), 1924 (s) cm-1 (CO). IR (KBr): ν 3449 (w), 3280
(w) cm-1 (NH); 1532 (s) cm-1 (CN). 1H NMR (300 MHz, CD2Cl2):
(1a-d · ClO4) were prepared according to a reported protocol.18
NMR spectra were recorded on Bruker 300 and 400 MHz
spectrometers. NMR multiplicities are abbreviated as follows: s )
singlet, d ) doublet, t ) triplet, dt ) doublet of triplets, m )
multiplet, br ) broad. Coupling constants, J, are given in Hz.
Methyl propiolate and phenyl acetylene were purchased from
Aldrich and used without previous purification.
Safety note: Perchlorate salts of metal complexes with organic
ligands are potentially explosive. Only small amounts of such
materials should be prepared, and these should be handled with
great caution.
3
3
δ 9.19 (2H, d, JHH ) 4.6, Ha bipy), 8.53 (2H, d, JHH ) 7.9, Hd
bipy), 8.25 (2H, t,3JHH ) 7.5, Hc bipy), 7.71 (2H, t,3JHH ) 6.2, Hb
bipy), 7.14-6.98 (3H, m, xylyl), 6.22 (1H, s, NH), 6.17 (1H, s,
NH), 3.14 (3H, d,3JHH ) 5.0, NCH3), 1.66 (2H,s, CH3 xylyl). 13C
NMR (75.5 MHz, CD2Cl2): δ 221.7 (s, Ccarbene); 215.5, 213.0 (br s,
CO), 155.5 (s, C1 bipy), 154.3 (s, C2 bipy), 140.4 (s, C3 bipy),
136.6 (s, Cipso xylyl), 132.5, 129.7, 129.5 (s, CHarom xylyl), 128.1(s,
C4 bipy), 124.7 (s, C5, bipy), 35.1 (s, CH3-NH), 17.7 (s, CH3 xylyl).
[Mn{C(NHC7H6Cl)(NHCH3)}(CO)3(bipy)][ClO4] (2d · ClO4). The
procedure was completely analogous to that described above, using
1d · ClO4 (0.1 g, 0.18 mmol) and a bubbling time of 15 min. Yield:
0.087 g (82%).Crystals of 2d · ClO4 suitable for X-ray diffraction
study were obtained by slow diffusion of hexane into CH2Cl2
solution of the compound. Anal. (%) Calcd for C22H19Cl2MnN4O7:
C 45.78, H 3.32, N 9.71. Found: C 45.30, H 3.30, N 9.69. IR
(CH2Cl2): ν 2033 (vs), 1953 (s), 1924 (s) cm-1 (CO). IR (KBr): ν
For the NMR spectra, the atom labeling in 2,2′-bipyridine and
in η4-azacyclohexadienyl ligands are as follows:
[Mn{C(NHPh)(NHCH3)}(CO)3(bipy)][BF4] (2a · BF4). Through
a solution of 1a · ClO4 (0.10 g, 0.20 mmol) in CH2Cl2 (10 mL),
NH2CH3 was bubbled for 3 min. The solution was then evaporated
to dryness, and the solid remaining was dissolved in CH2Cl2 (10
mL). After filtration, some KOH (0.25 g, 4.46 mmol) was added,
and the resulting mixture was stirred for 15 min. The red solution
was filtered off, and then HBF4 (0.028 mL, 54% w, 0,20 mmol)
was added to the solution, which immediately turned yellow. The
1
3445 (w), 3286 (w) cm-1 (NH), 1528 (s) cm-1 (CN). H NMR
3
(300 MHz, CD2Cl2): δ 9.17 (2H, d, JHH ) 5.4, Ha bipy), 8.49
(18) Garcia Alonso, F. J.; Riera, V.; Villafan˜e, F.; Vivanco, M. J.
Organomet. Chem. 1984, 276, 39.
3
(2H, d, JHH ) 8.0, Hd bipy), 8.27-8.18 (2H, m, Hc bipy),

Acyclic Diamino Carbene Complexes of Manganese(I)
Organometallics, Vol. 28, No. 3, 2009 835
7.74-7.67 (2H, m, Hb bipy), 7.23-7.15 (3H, m, Harom C7H6Cl),
6.28 (1H, s, NH), 6.13 (1H, s, NH), 3.21 (3H, d, 3JHH ) 5.1, NCH3),
1.83 (2H, s, CH3 C7H6Cl).
chromatographed on an alumina column (activity IV) at room
temperature. Elution with CH2Cl2/hexane (1:4) gave the ligand 2,2′-
bipyridine; next a second elution with CH2Cl2/hexane (1:1) gave a
yellow fraction. Removal of solvents from the latter and crystal-
lization in a mixture of CH2Cl2/hexane at -20 °C provided a yellow
microcrystalline solid. Yield: 0.036 g (35%). Anal. (%) Calcd for
C19H17MnN2O7: C 51.83, H 3.89, N 6.36. Found: C 51.80, H 3.85,
N 6.29. IR (CH2Cl2): ν 2004 (vs), 1926 (s), 1910 (sh) cm-1 (CO).
1H NMR (300 MHz, CD2Cl2): δ 7.42-7.28 (3H, m, Harom Ph), 7.04
[Mn{C(dNPh)(NHCH3)}(CO)3(bipy)] (3a). To a solution of
2a.BF4 (0.1 g, 0.019 mmol) in CH2Cl2 (10 mL), some KOH (0.50
g, 8.91 mmol) was added, and the mixture stirred for 20 min. The
color of the solution changed from yellow to red. Then the solution
was filtered off and concentrated to 3 mL. Hexane (10 mL) was
slowly added to give a red solid, which was filtered off and dried
under vacuum. Yield: 0.070 g (84%). Anal. (%) Calcd for
C21H17MnN4O3: C 58.89, H 4.00, N 13.08. Found: C 58.30, H 4.05,
N 13.09. IR (CH2Cl2): ν 2001 (vs), 1911 (s), 1892 (s) cm-1 (CO).
1H NMR (300 MHz, CD2Cl2): δ 8.72 (2H, d, 3JHH ) 5.0, Ha bipy),
7.96 (2H, d, 3JHH ) 7.9, Hd bipy), 7.80 (2H, t, 3JHH ) 7.5, Hc bipy),
3
4
(2H, d, JHH ) 7.3, Harom Ph), 6.72 (1H, d, JHH ) 1.0, HF), 5.21
(1H, s, NH), 3.90 (3H, s,CO2CH3), 3.46 (3H, s, CO2CH3), 3.02
3
2
(1H, d, JHH ) 1.0, HE), 2.93 (3H, d, JHH ) 2.5, NCH3).
[Mn{η4-C(CO2CH3)CHdC(CO2CH3)CHC(NHCH3)dN(C10H7)}-
(CO)3] (4b). The procedure was identical to that above-described,
but using 3b (0.1 g, 0.21 mmol) and 0.037 mL of methyl propiolate
(d ) 0.945 g/mL, 0.042 mmol) with a reaction time of 10 min.
Yield: 0.057 g (55%). Anal. (%) Calcd for C23H19MnN2O7: C 56.34,
H 3.91, N 5.71. Found: C 56.24, H 3.96, N 5.59. IR (CH2Cl2): ν
3
3
7.12 (2H, t, JHH ) 5.7, Hb bipy), 6.78 (2H, t, JHH ) 6.8, Hmeta
3
3
Ph), 6.62 (1H, t, JHH ) 6.8, Hpara Ph), 6.17 (2H, d, JHH ) 6.7,
Horto Ph), 4.43 (1H, s, NH), 2.52 (3H, br s, NCH3).
[Mn{C(dNC10H7(NHCH3)}(CO)3(bipy)] (3b). The procedure was
completely analogous to that described above, using 2b.BF4 (0.1
g, 0.18 mmol) and KOH (0.50 g, 8.91 mmol). Yield: 0.075 g (89%).
Anal. (%) Calcd for C25H19MnN4O3: C 62.77, H 4.00, N 11.71.
Found: C 62.30, H 4.11, N 11.49. IR (CH2Cl2): ν 2001 (vs), 1912
(s), 1892 (s) cm-1 (CO). 1H NMR (300 MHz, CD2Cl2): δ 8.69 (2H,
1
2004 (vs), 1926 (s), 1911 (sh) cm-1 (CO). H NMR (300 MHz,
CD2Cl2): δ 7.88-7.83 (3H, m, Harom C10H7), 7.58-7.52 (3H, m,
4
Harom C10H7), 7.09 (1H, dd, JHH ) 2.0,3JHH ) 8.5, Harom C10H7),
4
6.78 (1H, d, JHH ) 1.0, HF), 5.30 (1H, s, NH), 3.92 (3H,
4
s,CO2CH3), 3.42 (3H, s, CO2CH3), 3.07 (1H, d, JHH ) 1.0, HE),
3
3
2
d, JHH ) 4.3, Ha bipy), 7.94 (2H, d, JHH ) 8.1, Hd bipy), 7.74
(2H, t, 3JHH ) 7.6, Hc bipy), 7.66 (1H, d, 3JHH ) 8.1, C10H7), 7.45
(1H, d, 3JHH ) 8.1, C10H7), 7.36-7.30 (2H, m, Hb bipy), 7.26-7.19
(1H, m, C10H7), 6.86 (2H, t, 3JHH ) 5.8, C10H7), 6.66 (1H, s, C10H7),
2.92 (3H, d, JHH ) 4.8, NCH3).
[Mn{η4-C(CO2CH3)CHdC(CO2CH3)CHC(NHCH3)dN(xylyl)}-
(CO3)] (4c). The procedure was analogous to the synthesis of 4a,
using 3c (0.1 g, 0.22 mmol) and 0.039 mL of methyl propiolate (d
) 0.945 g/mL, 0.44 mmol). Yield: 0.062 g (60%). Anal. (%) Calcd
for C21H21MnN2O7: C 53.86, H 4.52, N 5.98. Found: C 53.82, H
4.40, N 5.83. IR (CH2Cl2): ν 2002 (vs), 1923 (s), 1908 (sh) cm-1
(CO).1H NMR (300 MHz, CD2Cl2): δ 7.15-7.13 (2H, m, Harom
4
3
6.40 (1H, dd, JHH ) 1.6, JHH ) 8.7, C10H7), 4.62 (1H, s, NH),
2.62 (3H, br s, CH3).
[Mn{C(dNXylyl)(NHCH3)}(CO)3(bipy)] (3c). The procedure was
analogous to the synthesis of 3a using 2c · ClO4 (0.1 g, 0.18 mmol)
and KOH (0.50 g, 8.91 mmol). Yield: 0.069 g (84%). Anal. (%)
Calcd for C23H21MnN4O3: C 60.53, H 4.64, N 12.28. Found: C
60.30, H 4.55, N 12.19. IR (CH2Cl2): ν 2000 (vs), 1907 (s), 1891
4
xylyl), 7.02-6.99 (1H, m, Harom xylyl), 6.83 (1H, d, JHH ) 1.2,
HF), 4.75 (1H, s, NH), 3.90 (3H, s, CO2CH3), 3.45 (3H, s, CO2CH3),
4
3.00 (1H, d, JHH ) 1.2, HE), 2.93 (3H, br s, NCH3), 2.43 (3H, s,
1
3
(s) cm-1 (CO). H NMR (300 MHz, CD2Cl2): δ 9.05 (2H, d, JHH
CH3 xylyl), 1.97 (3H, s, CH3 xylyl). 13C{1H} NMR (300 MHz,
CD2Cl2): δ 221.4 (br s, Mn-CO), 171.8 (s, C5), 169.9, 168.5 (s,
CO), 140.6 (s, Cipso xylyl), 134.9, 133.9 (s, Corto xylyl), 130.0, 129.6,
129.4 (s, Carom xylyl), 90.1 (s, C3), 87.2 (s, C1), 78.1 (s, C2), 52.7,
50.9 (s, OCH3), 38.8 (s, NCH3), 31,0 (s, C4), 18.9, 18.8 (s, CH3
xylyl).
3
) 5.4, Ha bipy), 8.07 (2H, d, JHH ) 8.1, Hd bipy), 7.87 (2H, t,
3JHH ) 7.8, Hc bipy), 7.32 (2H, t, JHH ) 6.4, Hb bipy), 6.64 (2H,
3
3
3
d, JHH ) 7.3, Hmeta xylyl), 6.45 (1H, t, JHH ) 7.3, Hpara xylyl),
4.42 (1H, d, 3JHH ) 4.0, NH), 2.61 (3H, d,3JHH ) 4.0, NCH3), 1.28
(6H, s, CH3 xylyl). 13C NMR (75.5 MHz, CD2Cl2): δ 226.7, 214.1
(br s, CO), 190.6 (s, Ccarbene), 156.9 (s, C1 bipy), 152.5 (s, C2 bipy),
136.9 (s, C3 bipy), 124.1 (s, C4 bipy), 121.6 (s, C5, bipy), 126.9,
119.0 (s, CHarom xylyl), 32.9 (s, CH3-NH), 18.0 (s, CH3 xylyl).
[Mn{C(dNC7H6Cl)(NHCH3)}(CO)3(bipy)] (3d). The procedure
was identical to the synthesis of 3a using 2d · ClO4 (0.1 g, 0.17
mmol) and KOH (0.50 g, 8.91 mmol). Yield: 0.071 g (86%). Anal.
(%) Calcd for C22H18ClMnN4O3: C 55.42, H 3.81, N 11.75. Found:
C 55.80, H 3.65, N 11.69. IR (CH2Cl2): ν 2002 (vs), 1910 (s), 1893
[Mn{η4-C(CO2CH3)CHdC(CO2CH3)CHC(NHCH3)dN(C7H6-
Cl)}(CO)3] (4d). The procedure was completely analogous to the
synthesis of 4a, using 3d (0.1 g, 0.21 mmol) and 0.037 mL of
methyl propiolate (d ) 0.945 g/mL, 0.42 mmol). Yield: 0.050 g
(49%). Crystals of 4d suitable for X-ray diffraction study were
obtained by slow diffusion of hexane into CH2Cl2 solution of the
compound. Anal. (%) Calcd for C20H18ClMnN2O7: C 49.15, H 3.71,
N 5.73. Found: C 49.32, H 3.67, N 5.70. IR (CH2Cl2): ν 2003 (vs),
1924 (s), 1909 (sh) cm-1 (CO).1H NMR (300 MHz, CD2Cl2): δ
1
3
(s) cm-1 (CO). H NMR (300 MHz, CD2Cl2): δ 9.06 (1H, d, JHH
3
) 5.4, Ha bipy), 8.98 (1H, d, JHH ) 5.4, Ha bipy), 8.05 (1H, d,
4
7.24-7.20 (3H, m, Harom C7H6Cl), 6.86 (1H, d, JHH ) 1.5, HF),
3JHH ) 7.9, Hd bipy), 8.04 (1H, d, 3JHH ) 7.9, Hd bipy), 7.88 (1H,
4.72 (1H, s, NH), 3.90 (3H, s, CO2CH3), 3.48 (3H, s, CO2CH3),
2.99 (1H, d, 4JHH ) 1.3, HE), 2.96 (3H, d, 3JHH ) 5.1, NCH3), 2.50
(3H, s, CH3 C7H6Cl).
t, 3JHH ) 7.5, Hc bipy), 7.86 (1H, t, 3JHH ) 7.5, Hc bipy), 7.37-7.30
3
(2H, m, Hb bipy), 6.78 (1H, d, JHH ) 7.9, Hmeta C7H6Cl), 6.71
3
3
(1H, d, JHH ) 7.3, Hmeta C7H6Cl), 6.44 (1H, t, JHH ) 7.7, Hpara
C7H6Cl), 4.48 (1H, s, NH), 2.54 (3H, d,3JHH ) 4.4, NCH3), 1.51
(3H, s, CH3 C7H6Cl).13C NMR (75.5 MHz, CD2Cl2): δ 225.5, 213.4
(br s, CO), 192.5 (s, Ccarbene), 156.1, 156.0 (s, C1 bipy), 152.4, 152.3
(s, C2 bipy), 149.1 (Cipso C7H6Cl), 136.8, 136.7 (s, C3 bipy), 129.9
(Cquat C7H6Cl), 127.1, 124.2, 118.5 (s, CHarom C6H5Cl), 124.2, 124.1
(s, C4 bipy), 121.3, 121.2 (s, C5, bipy), 32.0 (s, CH3-NH), 18.2 (s,
CH3 C7H6Cl).
[Mn{η4-C(CO2CH3)CHd(CO2CH3)CHC(NHCH3)dN(Ph)} (4a).
A solution of 3a (0.1 g, 0.23 mmol) in toluene (60 mL) was heated
to 60 °C with the help of a water bath, and when the temperature
was stable 2 equiv of methyl propiolate (0.042 mL, d ) 0.945 g/mL,
0.47 mmol) was added, and the mixture stirred for 15 min. After
that, the solvent was removed under vacuum, and the residues were
[Mn{η4-C(Ph)CHdC(Ph)CHC(NHCH3)dN(Ph)}(CO3)] (5a). To
a solution of 3a (0.05 g, 0.12 mmol) in toluene (30 mL), 4 equiv
of phenyl acetylene (0.051 mL, d ) 0.93 g/mL, 0.46 mmol) was
added, and the mixture was heated to 90 °C with the help of an oil
bath and stirred for 20 min. The solvent was then removed under
vacuum, and the residues were chromatographed on an alumina
column (activity IV) at room temperature. Elution with CH2Cl2/
hexane (1:3) gave the ligand 2,2′-bipyridine; next a second elution
with CH2Cl2/hexane (1:1) gave a yellow fraction. Removal of
solvents from the latter and crystallization in a mixture of CH2Cl2/
hexane at -20 °C provided a yellow microcrystalline solid. Yield:
0.022 g (43%). Anal. (%) Calcd for C27H21MnN2O3: C 68.07, H
4.44, N 5.88. Found: C 68.12, H 4.57, N 5.77. IR (CH2Cl2): ν 1982
(vs), 1896 (s), 1886 (sh) cm-1 (CO). 1H NMR (400 MHz, CD2Cl2):

836 Organometallics, Vol. 28, No. 3, 2009
Ruiz and Perandones
3
7.79 (2H, d, JHH ) 7.0, Harom Ph), 7.47-7.39 (5H, m, Harom Ph),
Single-Crystal X-ray Structure Determination of Compounds.
Suitable yellow single crystals of 2d, 4d, and 5c for the X-ray
diffraction study were selected. The data collection was carried out
at 110 K. The crystals were mounted on a Smart-CCD-1000
BRUKER single-crystal diffractometer equipped with a graphite-
monochromated Mo KR radiation (λ ) 0.71073 Å). Multiscan19
absorption correction procedures were applied to the data. The
structures were solved, using the WINGX package,20 by direct
methods (DIRDIF-99)21 and refined by using full-matrix least-
squared against F2 (SHELXL-97).22 All non-hydrogen atoms were
anisotropically refined. Hydrogen atoms were geometrically placed
and left riding on their parent atoms except for the hydrogen atoms
on C2 and C4 in compound 4d. Full-matrix least-squares refine-
7.24-7.12 (5H, m, Harom Ph), 7.02-6.96 (3H, m, Harom Ph), 6.44
(1H, s, HF), 5.18 (1H, s, NH), 3.24 (1H, s, HE), 3.03 (3H, d, JHH
3
) 3.0, NCH3). 13C{1H} NMR (400 MHz, CD2Cl2): 225.6 (br, Mn-
CO), 168.8 (s, C5), 142.9, 141.5, 139.9 (s, Cipso Ph), 129.5, 128.6,
127.8, 127.0, 126.9, 125.5, 124.9, 124.6 (s, Carom Ph), 102.6 (s,
C3), 83.3 (s, C1), 79.1 (s, C2), 44.0 (s, NCH3), 30.3 (s, C2).
[Mn{η4-C(Ph)CHdC(Ph)CHC(NHCH3)dN(C10H7)}(CO3)] (5b).
The procedure was completely analogous to the synthesis of 5a,
using 3b (0.05 g, 0.10 mmol) and 0.046 mL of phenyl acetylene
(d ) 0.93 g/mL, 0.42 mmol). The chromatography was similar to
that described above for the compound 5a. Yield: 0.031 g (56%).
Anal. (%) Calcd for C31H23MnN2O3: C 70.72, H 4.40, N 5.32.
Found: C 70.46, H 4.32, N 5.20. IR (CH2Cl2): ν 1982 (vs), 1897
(s), 1885 (sh) cm-1 (CO). 1H NMR (300 MHz, CD2Cl2): 7.84-7.64
(6H, m, Harom Ph and Naftil), 7.47-7.28 (8H, m, Harom Ph and
Naftil), 7.10-7.01 (3H, m, Harom Ph and Naftil), 6.48 (1H, s, HF),
5.28 (1H, s, NH), 3.22 (1H, s, HE), 3.00 (3H, d, 3JHH ) 3.1, NCH3).
[Mn{η4-C(Ph)CHdC(Ph)CHC(NHCH3)dN(Xylyl)}(CO)3] (5c).
The procedure was analogous to the synthesis of 5a, using 3c (0.05
g, 0.11 mmol) and 0.048 mL of phenyl acetylene (d ) 0.93 g/mL,
0.44 mmol). The chromatography was similar to that described for
the compound 5a. Yield: 0.031 g (56%). Crystals of 5c suitable
for X-ray diffraction study were obtained by slow diffusion of
hexane into CH2Cl2 solution of the compound. Anal. (%) Calcd
for C29H25MnN2O3: C 69.05, H 5.00, N 5.55. Found: C 69.35, H
4.92, N 5.40. IR (CH2Cl2): ν 1979 (vs), 1890 (s), 1881 (sh) cm-1
(CO). 1H NMR (400 MHz, CD2Cl2): 7.83 (2H, d, 3JHH ) 6.1, Harom
Ph), 7.48-7.39 (5H, m, Harom Ph), 7.12-6.89 (6H, m, Harom Ph
and xylyl), 6.42 (1H, s, HF), 4.55 (1H, s, NH), 3.06 (4H, br s, NCH3
and CHE), 2.49 (3H, s, CH3 xylyl), 2.08 (3H, s, CH3 xylyl). 13C{1H}
NMR (400 MHz, CD2Cl2): 225.0 (br s, Mn-CO), 170.7 (s, C5),
140.5, 139.7, 138.4 (s, Cipso Ph and xylyl), 134.8, 134.4 (s, Corto
xylyl), 129.3, 129.1, 128.9, 128.8, 128.5, 127.7, 127.4, 127.2, 126.2
(s, Carom Ph and xylyl), 103.8 (s, C3), 88.3 (s, C1), 80.6 (s, C2),
41.0 (s, NCH3), 30.4 (s, C4); 18.7, 18.3 (s, CH3 xylyl).
ments were carried out by minimizing ∑w(Fo - Fc2)2 with the
2
SHELXL-97 weighting scheme. The final residual electron density
map showed no remarkable features.
Acknowledgment. This work was supported by the
Spanish Ministerio de Educacio´n y Ciencia (PGE and
FEDER funding, Project CTQ2006-10035) and the Princi-
pado de Asturias (Project IB05-110). B.F.P. thanks the MEC
for a FPU grant.
Supporting Information Available: Crystallographic data in
CIF format of complexes 2d, 4d, and 5c. This material is available
free of charge via the Internet at http://pubs.acs.org.
OM800888R
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(22) Sheldrick, G. M. SHELXL97: Program for the Refinemet of Crystal
Structures; Universita¨t Go¨ttingen: Go¨ttingen, Germany, 1997.