Reactions of hydridoirida-β-diketones with amines or with 2-aminopyridines: Formation of hydridoirida-β-ketoimines, PCN terdentate ligands, and acyl decarbonylation

Article abstract of DOI:10.1021/ic202065d

The hydridoirida-β-diketone [IrHCl{(PPh₂(o-C ₆H₄CO))₂H}] (1) reacts with benzylamine (C ₆H₅CH₂NH₂) to give the hydridoirida-β-ketoimine [IrHCl{(PPh₂(o-C

Full text of DOI:10.1021/ic202065d

Article
pubs.acs.org/IC
Reactions of Hydridoirida-β-diketones with Amines or with
2-Aminopyridines: Formation of Hydridoirida-β-ketoimines,
PCN Terdentate Ligands, and Acyl Decarbonylation
Roberto Ciganda,† María A. Garralda,*,† Lourdes Ibarlucea,† Claudio Mendicute-Fierro,†
M. Carmen Torralba,‡ and M. Rosario Torres‡
†Facultad de Química de San Sebastian
́
, Universidad del País Vasco, Apdo. 1072, 20080 San Sebastian
́
, Spain
‡Departamento de Química Inorgan
́
ica, Laboratorio de Difraccion
́
de Rayos X, Facultad de Ciencias Químicas, Universidad
Complutense, 28040 Madrid, Spain
S
* Supporting Information
ABSTRACT: The hydridoirida-β-diketone [IrHCl{(PPh2(o-C6H4CO))2H}]
(1) reacts with benzylamine (C6H5CH2NH2) to give the hydridoirida-
β-ketoimine [IrHCl{(PPh2(o-C6H4CO))(PPh2(o-C6H4CNCH2C6H5))H}]
(2), stabilized by an intramolecular hydrogen bond. 2 reacts with water
to undergo hydrolysis and amine coordination giving hydridodiacylamino
[IrH(PPh2(o-C6H4CO))2(C6H5CH2NH2)] (3). Cyclohexylamine or dimethyl-
amine lead to hydridodiacylamino [IrH(PPh2(o-C6H4CO))2L] (4−5). In
chlorinated solvents hydridodiacylamino complexes undergo exchange of
hydride by chloride to afford [IrCl(PPh2(o-C6H4CO))2L] (6−9). The reac-
tion of 1 with hydrazine (H2NNH2) gives hydridoirida-β-ketoimine [IrHCl-
{(PPh2(o-C6H4CO))(PPh2(o-C6H4CNNH2))H}] (10), fluxional in solution
with values for ΔH⧧ of 2.5 0.3 kcal mol−1 and for ΔS⧧ of −32.9 3 eu. A
hydrolysis/imination sequence can be responsible for fluxionality. 2-Amino-
pyridines (RHNC5H3R′N) react with 1 to afford cis-[IrCl(PPh2(o-C6H4CO))(PPh2(o-C6H4CHNRC5H3R′N))] (R = R′ = H (11), R =
CH3, R′ = H (12), R = H, R′ = CH3 (13)) containing new terdentate PCN ligands in a facial disposition and cis phosphorus atoms as
kinetic products. The formation of 11−13 requires imination of the hydroxycarbene moiety of 1, coordination of the nitrogen atom of
pyridine to iridium, and iridium to carbon hydrogen transfer. In refluxing methanol, complexes 11−13 isomerize to afford the
thermodynamic products 14−16 with trans phosphorus atoms. Chloride abstraction from complexes [IrCl(PPh2(o-C6H4CO))(PPh2-
(o-C6H4CHNRC5H4N))] (R = H or CH3) leads to decarbonylation of the acylphosphine chelating group to afford cationic complexes
[Ir(CO)(PPh2(o-C6H4))(PPh2(o-C6H4CHNRC5H4N))]A, 17 (R = H, A = ClO4) and 18 (R = CH3, A = BF4) as a cis/trans = 4:1
mixture of isomers. Single crystal X-ray diffraction analysis was performed on 6, 9, 13, and 14.
production is the subject of recent intensive research.6 Plausible
INTRODUCTION
■
mechanisms considered to account for the heterogeneous
transition metal catalyzed hydrolysis of NH3BH3 (AB) include
the formation of an activated complex species between AB and the
metal particle surface to which attack by a H2O molecule leads to
concerted dissociation of the B−N bond and the hydrolysis of the
resulting BH3 intermediate.7 The cleavage of the B−N bond may
afford the amine. Metalla-β-diketones are known to react with
ammonia or amines to afford metalla-β-ketoimines.8 In our pre-
liminary communication we have reported that the hydridoirida-
β-diketone [IrHCl{(PPh2(o-C6H4CO))2H}] (1) reacts with
methylamine to afford a hydridometalla-β-ketoimine, which was
characterized by single crystal X-ray diffraction.5
Hydridoirida-β-diketones such as [IrHCl{(PPh2(o-C6H4CO))2H}]
(1) can be considered as acylhydroxycarbene complexes, stabilized
by a strong intramolecular hydrogen bond between the acyl and
the hydroxycarbene moieties. These complexes can be easily
obtained by the reaction of the hydridoacyliridium(III) complex
[Ir(Cod)(Cl)H(PPh2(o-C6H4CO))] (Cod = 1,5-cyclooctadiene)
with chelating aldehydes in methanol.1 Hydridoirida-β-diketones
may undergo reversible deprotonation and/or dehydrogenation
reactions to afford diacyl [IrH(PPh2(o-C6H4CO))2L] (L = CO,
C2H4, DMSO, PPh3, py), [Ir(Cl)(PPh2(o-C6H4CO))2(py)],
[Ir2H2(PPh2(o-C6H4CO))2(μ-PPh2(o-C6H4CO))2], [Ir2(μ-H)
{μ-PPh2(o-C6H4CO)}2(PPh2(o-C6H4CO))2]+, [Ir2H(PPh2-
(o-C6H4CO)){μ-PPh2(o-C6H4CO)}3]+, or [Ir2(μ-Cl){μ-PPh2(o-
C6H4CO)}2(PPh2(o-C6H4CO))2]+ species.2−4 Recently, we have
found that complex 1 is an efficient homogeneous catalyst for
the hydrolysis of ammonia- or amine-borane adducts for hydro-
gen generation.5 The transition-metal catalyzed dehydrogenation
of these potential hydrogen storage materials for hydrogen
We report now on the reaction of 1 with primary or
secondary amines, hydrazine, or 2-aminopyridines to afford
hydridoirida-β-ketoimines, which can undergo reversible
Received: September 21, 2011
Published: January 18, 2012
© 2012 American Chemical Society
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hydrolysis reactions, or new iridium coordinated terdentate
PCN ligands.
The reaction of 1 with cyclohexylamine (C6H11NH2) in CH2Cl2
leads only to complex 4. The reaction of 1 with cyclohexylamine or
with the secondary amine (CH3)2NH in a THF/H2O = 1/1
mixture, leads to 4 or 5, respectively. Complex 1 fails to react with
the tertiary amine NEt3 in dry solvents and reacts in THF/H2O =
1/1 mixtures to afford the known acyl-bridged species
[Ir2H2(PPh2(o-C6H4CO))2(μ-PPh2(o-C6H4CO))2], reported to
react with different donor ligands to form hydridodiacyliridium(III)
complexes analogous to 3−5.3 We observe now that the dimer
[Ir2H2(PPh2(o-C6H4CO))2(μ-PPh2(o-C6H4CO))2] fails to react
with cyclohexylamine or with dimethylamine. Therefore, we
believe that the transformation of 1 into 4 or 5 may proceed via
the sequence shown in Scheme 1. Formation of a condensation
reaction product (i), unstable for compounds with bulky amino
substituents, cyclohexylamine, or when the condensation reaction
cannot result in the formation of the N---H---O hydrogen bond,
dimethylamine, followed by hydrolysis (ii). An aromatic amine,
aniline, fails to react with 1 under the studied reaction conditions.
In chlorinated solvents hydridodiacylamino complexes 3−5,
and also [IrH(PPh2(o-C6H4CO))2(CH3NH2)],5 undergo the
exchange of hydride by chloride to afford complexes [Ir(Cl)-
(PPh2(o-C6H4CO))2L] 6−9 (Scheme 1iv). Such a reaction has
several precedents.9 This exchange occurs with concomitant
isomerization as shown by an X-ray diffraction study. While in
complexes 3−5 the amino group is trans to the acyl group, in
complexes 6−9 the acyl group is trans to chloride and the
amino goup is trans to phosphine. The formation of 6−9 was
demonstrated spectroscopically. The 13C{1H} NMR spectra
show doublets in the 233−230 ppm range (2J(P,C) of 108 Hz)
and resonances in the 210−207 ppm range due to acyl groups
RESULTS AND DISCUSSION
Reaction with Amines or Hydrazine. The reaction of 1 with
benzylamine (C6H5CH2NH2) (see Scheme 1i) in CH2Cl2 leads
■
a
Scheme 1
a
(i) R = C6H5CH2 (2) in CH2Cl2; R = NH2 (10) in THF or THF/
H2O. (ii) 2 in THF/H2O. (iii) L = C6H5CH2NH2 (3); C6H11NH2
(4); (CH3)2NH (5) in THF/H2O. (iv) L = C6H5CH2NH2 (6);
C6H11NH2 (7); CH3NH2 (8); (CH3)2NH (9) in refluxing CCl4.
1
trans or cis to phosphorus atoms respectively. The H NMR
spectra show one of the resonances due to the amino groups at
rather high field, in the 5.99−5.29 ppm range, and suggest the
presence of intramolecular hydrogen bonds. The 31P{1H}
NMR spectra show two doublets at 23 and 9 ppm respectively
to the condensation reaction product, hydridoirida-β-ketoimine
[IrHCl{(PPh2(o-C6H4CO))(PPh2(o-C6H4CNCH2C6H5))H}]
2, stabilized by an intramolecular hydrogen bond between the
keto and the enamine moieties. Complex 2 was fully
characterized spectroscopically. The 31P{1H} NMR spectrum
of 2 shows two doublets at 30.4 and 15.3 ppm with 2J(P,P) of 7
Hz, the 13C{1H} NMR spectrum shows two doublets at 243.3
and 223.0 ppm due to acyl and imino groups trans to
phosphorus atoms (2J(P,C) of 106 and 103 Hz respectively),
2
with J(P,P) of 4 Hz, for complexes 6−8, containing primary
amines and two singlets at higher field, 17.5 and 7.7 ppm, for
complex 9. On account of these spectroscopic data it is not
possible to distinguish between the disposition shown in
Scheme 1 and an isomer containing the amino group trans to
the acyl group as in complexes 3−5.
1
and the H NMR spectrum shows a hydride resonance in the
2
high field region, at −20.47 ppm, as triplet due to J(P,H) of
An X-ray diffraction study on complexes 6, [C45H37Cl-
NO2P2Ir]·1/2C4H10O and 9, [C40H35ClNO2P2Ir] confirms the
isomerization reaction. These compounds crystallized in the
C2/c monoclinic group. Figure 1 and Figure 2 show ORTEP
views of complexes 6 and 9, respectively. Selected bond
distances and angles are reported in Table 1. In both
compounds the crystal consists of neutral Ir complexes and
for 6 half a solvent molecule of diethyl ether is also present.
The coordinative environment of the Ir atom is slightly
distorted octahedral with four positions occupied by the two
bidentate acylphosphine ligands and the other two positions
occupied by the amino and the chloride ligands. The P1−Ir−P2
bond angles (100.2 (1) and 98.4(1)°) confirm that, in both
cases, the phosphorus atoms are mutually cis, with P1 trans to
one acyl group and P2 trans to the amino group. Inspection of
the bond lengths in these complexes shows that the Ir−N,
Ir−P, Ir−C, and Ir−Cl bond distances are in the expected
ranges.4,10 The Ir−P bond distance values of 2.360(2) Å for P1,
trans to the acyl group, and of 2.275(2) Å for P2, trans to the
amino group, agree with the trans influence order of the
ligands: acyl ≫ amine.11 In these complexes the amino group
forms a strong intramolecular hydrogen bond with the oxygen
14.2 Hz, which agrees with the hydride being trans to chlorine
and cis to two phosphines, and a low field singlet at 13.40 ppm
that supports the presence of fairly strong N···H···O hydrogen
bonds and the existence of a irida-β-ketoimine. In tetrahydrofuran
(THF) solution, 2 reacts with water to undergo hydrolysis and
amine coordination thus affording the hydridodiacylamino complex
[IrH(PPh2(o-C6H4CO))2(C6H5CH2NH2)] 3, as shown in
Scheme 1ii. The 31P{1H} NMR spectrum of 3 shows two
2
doublets at 31.0 and 25.4 ppm with J(P,P) of 4 Hz. In the 31P
NMR spectrum, the signal at 31.0 ppm appears as doublet with
2J(H,P)trans of 130 Hz. The 13C{1H} NMR spectrum shows a
doublet at 239.0 (2J(P,C) of 102 Hz) and a singlet at 213.6 ppm
respectively due to acyl groups trans or cis to phosphorus atoms,
and the 1H NMR spectrum shows a hydride resonance in the high
field region, at −7.83 ppm, as doublet of doublet due to 2J(P,H)trans
2
of 130.2 Hz and J(P,H)cis of 19.8 Hz, along with the resonances
due to the coordinated amine at 2.61 and 1.87 ppm, at lower field
than that of the free ligand. All these data agree with the structure
shown in Scheme 1. Complex 3 is most conveniently prepared by
the reaction of 1 with C6H5CH2NH2 in a THF/H2O = 1/1
mixture (Scheme 1iii).
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Table 1. Selected Bond Lengths (Å) and Angles (deg) for 6
and 9
6
9
Ir−P1
Ir−P2
Ir−C1
Ir−C20
Ir−CL
Ir−N1
C1−O1
C20−O2
N1−H1
2.360(2)
2.275(2)
2.005(8)
2.066(8)
2.511(2)
2.164(6)
1.232(9)
1.226(9)
0.94
Ir−P1
Ir−P2
Ir−C1
Ir−C20
Ir−CL
Ir−N1
C1−O1
C20−O2
N1−H1
2.361(3)
2.279(3)
2.02(1)
2.06(1)
2.510(2)
2.21(1)
1.22(1)
1.22(1)
0.98
N1−H2
1.09
N1---O2
2.752(9)
2.10
N1---O2
2.70(1)
2.06
O2···H1
O2···H1
P1−Ir−CL
P1−Ir−C20
P1−Ir−C1
P1−Ir−P2
P1−Ir−N1
CL−Ir−C20
CL−Ir−C1
CL−Ir−P2
CL−Ir−N1
C20−Ir−C1
C20−Ir−P2
C20−Ir−N1
C1−Ir−P2
C1−Ir−N1
P2−Ir−N1
N1−H1−O2
96.3(1)
173.2(2)
84.0(2)
100.2(1)
92.5(2)
88.6(2)
170.7(2)
100.4(1)
79.0(2)
90.4(3)
83.4(2)
83.9(3)
88.7(3)
91.7(3)
167.3(2)
125.5
P1−Ir−CL
P1−Ir−C20
P1−Ir−C1
P1−Ir−P2
P1−Ir−N1
CL−Ir−C20
CL−Ir−C1
CL−Ir−P2
CL−Ir−N1
C20−Ir−C1
C20−Ir−P2
C20−Ir−N1
C1−Ir−P2
C1−Ir−N1
P2−Ir−N1
N1−H1−O2
96.3(1)
174.0(3)
84.9(3)
98.4(1)
96.0(3)
88.9(3)
176.1(3)
97.4(1)
86.7(3)
89.7(4)
83.7(3)
81.4(4)
86.0(3)
89.5(4)
164.5(3)
120.5
Figure 1. ORTEP plot (25% probability ellipsoids) of complex 6,
showing the labeling of the asymmetric unit. The solvent molecule and
the hydrogen atoms except two, have been omitted for clarity.
atom of an acyl group N1−H1---O2 (N1---O2 = 2.752(9) Å or
2.70(1) Å for 6 or 9 respectively). We observe that the
intramolecular hydrogen bond formation occurs between the
amino group and the acyl group trans to P with the longest Ir−
C bond distance (2.066(8) Å), rather than with the acyl group
trans to chloride, with shorter Ir−C bond distance (2.005(8) Å).
This preference has also been observed in related diacyldi-
aminerhodium(III) complexes.11b
pound is fluxional in solution as shown by inspection of the
31P{1H} and 1H NMR spectra in THF-d8. At 173 K the 31P{1H}
NMR spectrum shows two singlets at 19.8 and 13.3 ppm and the
1H NMR spectrum shows a resonance in the high field region, at
−19.11 ppm, as triplet (2J(P,H) of 16.8 Hz) due to a hydride cis
The reaction of 1 with hydrazine (H2NNH2) (see Scheme 1i)
in dry THF leads to the hydridoirida-β-ketoimine [IrHCl-
{(PPh2(o-C6H4CO))(PPh2(o-C6H4CNNH2))H}] 10. This com-
Figure 2. ORTEP plot (20% probability ellipsoids) of complex 9, showing the labeling of the asymmetric unit. The solvent molecule and the
hydrogen atoms except one, have been omitted for clarity.
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to two phosphorus atoms, a resonance at 3.21 ppm due to the
amino group and a low field singlet at 14.16 ppm due to the
N···H···O hydrogen bond of the irida-β-ketoimine. On raising the
temperature the signals due to the phosphorus atoms broaden
and coalescence occurs at 263 K (see Figure 3), while the
corresponding hydridodiacylhydrazineiridium(III) derivative of
the 3−5 type was not observed.
Reaction with 2-Aminopyridines. 2-Aminopyridines are
well-known to form a variety of complexes behaving as a
monodentate N-pyridine ligand.15 Their reaction with acylhy-
droxycarbene platinum(II) complexes has been reported to
yield cyclic five-membered PtNCNC aminocarbene deriva-
tives;16 therefore, we thought it interesting to study the reaction
of complex 1 with these ligands. These reactions could also be
of interest because the catalytic hydrolysis of ammonia- or
amine-boranes with complex 1 could involve interactions of
the iridium atom with the borane fragment and of the
hydroxycarbene moiety with the amino fragment thus affording
IrHBNC metallocyles. Ammonia- or amine-borane adducts can
coordinate to transition metals to afford a variety of σ-borane com-
plexes, or compounds containing M−H−BHnR2−n−NHnR3−n
fragments.17
2-Aminopyridines react with 1 in a dichloromethane/
methanol mixture, at room temperature, to afford complexes
11−13 containing new terdentate PCN ligands with a coor-
dinated sp3 carbon atom as shown in Scheme 3i. The
NMR spectra, including 2D experiments, agree with the
formation of the new C−N bonds and with the structure
shown in Scheme 3i. The 31P{1H} NMR spectra show two
a
Scheme 3
Figure 3. Variable-temperature 31P{1H} NMR spectra of 10 in THF-d8:
(left) experimental and (right) calculated.
resonances due to the amino group and to the N···H···O moiety
also broaden and coalesce. The resonance due to the hydride
remains as a triplet. These features indicate exchange between
the keto and the imine moieties as shown in Scheme 2. From
Scheme 2. Exchange between the Keto and the Imine
Moieties in 10
a
(i) R = R′ = H (11), R = CH3, R′ = H (12), R = H, R′ = CH3 (13) in
CH2Cl2/CH3OH; (ii) R = R′ = H (14), R = CH3, R′ = H (15), R = H,
R′ = CH3 (16) in refluxing CH3OH.
line-shape analysis12 of the variable temperature 31P{1H} NMR
spectra of complex 10, the activation parameters ΔH⧧ = 2.5
0.3 kcal mol−1 and ΔS⧧ = −32.9 3 cal K−1 mol−1 have been
determined. The enthalpy of activation indicates a low activation
barrier. The high entropy of activation suggests an associative
mechanism,13 which could occur by interaction of adventitious
water with the imino fragment in 10a to afford its hydrolysis and
deliver free hydrazine, which could promote again the imination
reaction giving 10b and the observed site exchange. This behavior
suggests that the irida-β-ketoimine formation shown in Scheme 1i
can be a reversible reaction.
2
doublets at 24 and 17 ppm respectively with J(P,P) of 4 Hz,
due to phosphorus atoms in mutually cis positions. The
13C{1H} NMR spectra show singlets in the 219−216 ppm
range due to terminal acyl groups bonded to iridium and
doublets in the 76−66 ppm range due to benzylic carbon atoms
trans to phosphorus (2J(P,C) of 84 Hz), which correlate with
1
resonances in the 6.2−5.8 ppm range in the H NMR spectra
that also contain the resonances due to the amino groups at
5.29 or 5.78 ppm for compounds 11 or 13, respectively. PCN
ligands may adopt meridional or facial coordination patterns in
octahedral transition metal complexes, and some cationic
Ir(III) complexes have been reported to undergo the fac-mer
isomerization reaction.18 As indicated by an X-ray diffraction
Some hydridohydrazineiridium(III) complexes are known,14
so we thought that the reaction of 1 with hydrazine (H2NNH2)
in THF/H2O = 1:1 could afford a complex similar to 3−5. This
last reaction gave only complex 10, and the formation of the
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study (vide infra), the PCN terdentate ligand in complexes
11−13 adopts a facial disposition.
Table 2. Selected Bond Lengths (Å) and Angles (deg) for 13
and 14
a
We believe that the formation of complexes 11−13 involves
a condensation reaction to yield a transient aminocarbene
followed by iridium to carbon hydrogen transfer, with
concomitant coordination of the nitrogen atom of pyridine to
iridium. Most likely, in the present reaction the coordination of
pyridine makes the formed aminocarbene fragment to be
involved in a five-membered IrNCNC metallacycle thus inhi-
biting the formation of a N---H---O hydrogen bond with the
keto group. The lack of stabilization would be responsible for
the observed iridium to carbon hydrogen transfer to afford
complexes 11−13. α-Hydrogen transfer has been reported for
hydrido-carbene iridium complexes.19 As indicated previously
we have observed that aromatic amines fail to afford the
imination reaction and in a previous report we described that
the reaction of 1 with pyridine in refluxing methanol led to a
diacylpyridine complex with hydrogen loss.4 In contrast, 2-
aminopyridines afford a new reaction, most likely favored by
chelate formation, to give the five-membered IrNCNC
metallacycle.
13
14
Ir−P1
Ir−P2
Ir−C1
Ir−C20
Ir−CL1
Ir−N1
C1−O1
C20−N2
N2−H2
2.3552(7)
2.2526(7)
2.020(3)
2.110(3)
2.4304(7)
2.160(2)
1.224(3)
1.467(3)
0.93
Ir−P1
Ir−P2
Ir−C1
Ir−C20
Ir−CL1
Ir−N1
C1−O1
C20−N2
2.307(3)
2.307(3)
1.98(1)
2.082(8)
2.468(2)
2.145(7)
1.23(1)
1.47(1)
1.04
N2−H2
N2---O2
3.584(4)
2.70
N2---CL1′
CL1′···H2
P1−Ir−CL1
P1−Ir−C20
P1−Ir−C1
P1−Ir−P2
P1−Ir−N1
CL1−Ir−C20
CL1−Ir−C1
CL1−Ir−P2
CL1−Ir−N1
C20−Ir−C1
C20−Ir−P2
C20−Ir−N1
C1−Ir−P2
C1−Ir−N1
P2−Ir−N1
3.244(7)
2.29
O2···H2
P1−Ir−CL1
P1−Ir−C20
P1−Ir−C1
P1−Ir−P2
P1−Ir−N1
CL1−Ir−C20
CL1−Ir−C1
CL1−Ir−P2
CL1−Ir−N1
C20−Ir−C1
C20−Ir−P2
C20−Ir−N1
C1−Ir−P2
C1−Ir−N1
P2−Ir−N1
90.17(3)
173.29(7)
83.47(8)
102.52(3)
104.63(7)
85.51(8)
83.71(8)
165.42(3)
86.35(7)
91.0(1)
88.03(9)
97.2(3)
83.2(3)
172.29(9)
95.0(2)
170.6(3)
95.2(2)
94.93(9)
90.5(2)
93.2(3)
80.9(3)
81.3(3)
89.4(3)
174.0(3)
92.1(2)
108.3(7)
151.8
Complexes 11−13 are the kinetic products of this reaction.
When refluxed in methanol for 90 min, the isomerization
reaction occurs to afford the thermodynamic products 14−16
with also a facial disposition of the PCN ligand, trans
phosphorus atoms and with the chloride trans to the benzyl
group as shown in Scheme 3ii. Complexes 14−16 can be more
easily obtained by the reaction of 1 with the corresponding 2-
aminopyridine in refluxing methanol. The 31P{1H} NMR
spectra show two doublets at slightly lower field than in
81.18(8)
80.3(1)
90.56(8)
167.2(1)
97.17(7)
110.8(2)
158.9
C21−C20−N2
N2−H2−O2
C21−C20−N2
N2−H2−CL1′
2
complexes 11−13, in the 33−23 ppm range, with J(P,P) of
390 Hz, due to phosphorus atoms in mutually trans positions.
The 13C{1H} NMR spectra show the expected singlets at
218 ppm due to the terminal acyl groups bonded to iridium and
in the 54−44 ppm range due to the benzyl groups. The latter
resonances correlate with resonances in the 4.6−4.2 ppm range
a
(′) −x+2, y+1/2,−z+1/2.
1
in the H NMR spectra that also show resonances at 4.09 and
3.83 ppm due to the amino groups in 14 and 16, respectively.
Complexes 11−16 contain an asymmetric sp3 carbon atom
newly formed. These complexes are diastereomeric because the
iridium atom is also chiral. In all cases only one group of
resonances is observed and indicates the formation of only a
pair of enantiomers of the four possible diastereomers.
An X-ray diffraction study on complexes 13 and 14 was
undertaken and confirms the formation of new C−N bonds
and the Ir-to-C hydrogen transfer to give the final products.
These compounds crystallized in the P1 triclinic group and in
̅
the P21/c monoclinic group respectively. The crystals consist of
[C44H36ClN2OP2Ir] neutral molecules and diethyl ether solvent
molecules bonded by weak hydrogen bond for 13, and of
[C43H34ClN2OP2Ir] neutral molecules and dichloromethane
solvent molecules for 14. In the latter compound the
intermolecular hydrogen bond (Table 2) led to chains along
the a axis. Figure 4 and Figure 5 show the ORTEP views of the
complexes with the atomic numbering scheme. Selected bond
distances and angles are listed in Table 2. The C20−N2 bond
distances, 1.467(3) and 1.47(1) Å for 13 and 14 respectively,
along with the C21−C20−N2 bond angle of 110.8(2)° and
108.3(7) for 13 and 14, respectively, show the new C−N bond
formation, with C20 changing from sp2 to sp3. The iridium
atom in compounds 13 and 14 is coordinated in a slightly
distorted octahedral fashion because of the presence of a
bidentate and a terdentate ligand. The maxima deviation from
Figure 4. ORTEP plot (20% probability ellipsoids) of complex 13,
showing the labeling of the asymmetric unit. The solvent molecule and
the hydrogen atoms except two have been omitted for clarity.
the octahedral geometry corresponds to 15° for the angle
CL1−Ir−P2 for 14 and 13° for the angle C1−Ir−N1 for 13.
Compounds 13 and 14 can be considered as geometric
isomers, although the terdentate ligands derive from 2-amino-3-
methylpyridine or 2-aminopyridine, respectively. The most
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Inorganic Chemistry
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a
Scheme 4
a
(i) AgClO4 in CH2Cl2, 17 (R = H); Et3OBF4 in CH2Cl2, 18 (R =
CH3).
decarbonylation of acyl halides or of aldehydes has been
established as a useful synthetic transformation. Nevertheless,
chelate formation frequently renders the decarbonylation reaction
more difficult and halide abstraction from rhodium or iridium
complexes containing acylphosphine chelates frequently results in
the formation of dimer species with acyl bridging groups.24
Complexes 17 and 18 behave as 1:1 electrolytes and were
identified spectroscopically. The appearance of resonances in the
31P{1H} NMR spectra at very high field, −66 ppm, which
represents shifts over +80 ppm to higher fields with respect to the
starting materials, indicates the formation of four-membered
metallacycles.25 The trans isomers, show two doublets with 2J(P,P)
of 340 Hz. The cis-17 isomer also shows two doublets with
2J(P,P) of 7 Hz, and the cis-18 isomer shows two singlets due to
Figure 5. ORTEP plot (20% probability ellipsoids) of complex 14,
showing the labeling of the asymmetric unit. The solvent molecule and
the hydrogen atoms except two have been omitted for clarity.
notable difference observed in these compounds is the cis
coordination of the phosphorus atoms in 13 while they are
trans coordinated in 14. The bond angles closest to the linearity
correspond to P1−Ir−C20 for 13 (173.29(7)°) and P1−Ir−P2
for 14 (172.29(9)°). For this reason, those donor atoms were
considered to occupy the apical positions. In consequence the
equatorial plane is formed by [P2, C1, CL1, N1] for 13 and by
[C1, C20, N1, CL1] for 14. The Ir atom is shifted away from
the best least-squares plane by 0.22 Å in the former, while it is
practically on the equatorial plane in the latter. In 13, the Ir−P
bond distances, shorter for P2, trans to chloride, than for P1,
trans to the C20 atom of the terdentate ligand, reflect the
higher trans influence of alkyl than that of chloride. In 14, the
Ir−P bond distances are equal as expected. Also, the Ir−C1
bond distances are shorter than the Ir−C20 bond distances as a
consequence of the different hybridization for C1 (sp2) than for
C20 (sp3).10a,20
In an attempt to obtain PCN unsaturated 16e species, we
have studied the chloride abstraction reaction from complexes
11 or 12 by using AgClO4 or Et3OBF4. Unsaturated pincer
complexes, especially those involving a meridional disposition
for the terdentate ligand, are of considerable current interest, as
they may lead to a variety of bond activation and catalytic
processes.21 An unsaturated Ir-pincer complex is an efficient
catalyst for the dehydrocoupling of amine-boranes under
anhydrous conditions.22 As shown in Scheme 4, the formation
of stable unsaturated 16e species does not occur. Instead, the
decarbonylation of the acylphosphine chelating group occurs to
afford coordinatively saturated complexes 17 and 18 as a cis/
trans = 4:1 mixture of isomers. By starting from complexes
14 or 16, the same mixture of isomers was obtained.
Orthometalated complexes containing the M[PPh2(o-C6H4)]
fragment are well-known.23 However, the formation of 17 and
18 was unexpected to some extent because it requires
decarbonylation of an acylphosphine chelate. Transition metal
acyl complexes may undergo decarbonylation to afford
carbonylated metal complexes. The transition metal promoted
2
unobservable J(P,P). The presence of the coordinated carbonyl
group, cis to phosphorus atoms in these compounds, is identified
by the appearance of strong absorptions at 2040 cm−1 in the IR
spectra and by the presence of triplets at 168 ppm (2J(P,C) = 5
Hz) in the 13C{1H} NMR spectra. The carbon atoms of the PCN
ligands appear as doublets (2J(P,C)trans = 70 Hz) in the cis isomers
and as singlets in the trans isomers. Assuming a facial disposition
of the PCN ligand these NMR data indicate the structure shown
in Scheme 4 for the cis isomers. For the trans isomers a disposition
with the nitrogen atom trans to the aryl ligand, with larger
structural trans effect than CO,11a appears more likely though the
other disposition, trans to CO, cannot be totally excluded.
CONCLUSIONS
■
Hydridoirida-β-diketones react with aliphatic amines or with
hydrazine to afford, reversibly, hydridoirida-β-ketoimines that may
also undergo hydrolysis to afford hydridodiacylaminoiridium(III)
derivatives. The reaction of hydridoirida-β-diketones with 2-amino-
pyridines leads to imination and to iridium to carbon hydrogen
transfer to afford the formation of complexes containing new
terdentate PCN ligands. These complexes containing pincer and
acylphosphine ligands may undergo decarbonylation of the
chelating acylphosphine ligands at room temperature.
EXPERIMENTAL SECTION
General Procedures. The preparation of the metal complexes was
carried out at room temperature under nitrogen by standard Schlenk
■
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techniques. The complexes [IrHCl{(PPh2(o-C6H4CO))2H}]1a (1)
and [IrH(PPh2(o-C6H4CO))2(CH3NH2)]5 were prepared as pre-
viously reported. Microanalysis were carried out with a Leco CHNS-
932 microanalyzer. Conductivities were measured in acetone solution
with a Metrohm 712 conductimeter. IR spectra were recorded with a
Nicolet FTIR 510 spectrophotometer in the range 4000−400 cm−1
using KBr pellets. NMR spectra were recorded with Bruker Avance
DPX 300 or Bruker Avance 500 spectrometers; 1H and 13C{1H}
(TMS internal standard), 31P{1H} (H3PO4 external standard) and 2D
spectra were measured from CDCl3 or THF-d8 solutions.
C44H41ClIrNO2P2: C, 58.37, H, 4.56, N, 1.55; found: C, 58.49, H,
4.47, N, 1.74. H NMR (CDCl3): δ 5.39 (m, 1H, NH); 3.10 (m, 1H,
1
NH and 1H, CH cyclohexyl), 2.50 to −0.02(m, 10H, cyclohexyl).
31P{1H}NMR (CDCl3): δ 22.6 (d, JP,P = 3 Hz); 8.4 (d). 13C{1H}NMR
(CDCl3): δ 230.9 (d, JP,C = 108 Hz, IrCO); 207.2 (s, IrCO).
Data for 8. Yield: 28 mg, 90%. IR (cm−1): 3312 (w), 3145 (w),
ν(NH); 1621 (s), ν(CO). Anal. Calc. for C39H33ClIrNO2-
P2·0.25CH3Cl: C, 54.92, H, 3.91, N, 1.63; found: C, 54.78, H, 3.95,
1
N, 1.61. H NMR (CDCl3): δ 5.29 (s, br, 1H, NH); 2.81 (s, br, 1H,
NH); 1.78 (m, 3H, CH3). 31P{1H}NMR (CDCl3): δ 22.9 (d, JP,P = 5
Hz); 10.5 (d). 13C{1H}NMR (CDCl3): δ 231.8 (d, JP,C = 109 Hz,
IrCO); 208.2 (d, JP,C = 7 Hz); 31.6 (s, CH3). Data for 9. Yield: 32
mg, 59%. IR (cm−1): 3134 (w), ν(NH); 1614 (s), 1571 ν(CO).
Anal. Calc. for C39H33ClIrNO2P2·0.5CH2Cl2: C, 54.42, H, 4.06, N,
Preparation of [IrHCl{(PPh2(o-C6H4CO)(PPh2(o-C6H4CN-
(CH2C6H5))H}] (2). To a dichloromethane solution of 1 (50 mg,
0.062 mmol) was added benzylamine (6.8 μL, 0.062 mmol) and 4 Å
molecular sieve. Stirring during 2 h and evaporation of the solvent gave
a yellow solid that was washed with diethyl ether and vacuum-dried.
Yield: 41 mg, 74%. IR (cm−1): 2169 (m), ν(IrH); 1592 (s), 1566 (s),
ν(CO). Anal. Calc. for C45H36ClIrNOP2: C 60.30, H 4.05, N 1.56;
1
1.57; found: C, 54.72, H, 4.06, N, 1.63. H NMR (CDCl3): δ 5.99 (s,
br, 1H, NH); 2.00 (m, 6H, CH3). 31P{1H}NMR (CDCl3): δ 17.5 (s);
7.7 (s). 13C{1H}NMR (CDCl3): δ 232.7 (d, JP,C = 109 Hz, IrCO);
210.0 (d, JP,C = 8 Hz); 44.6 (s, CH3); 40.8 (s, CH3).
1
found: C 60.39, H 3.64, N 1.89. H NMR (CDCl3): δ 13.40 (s, 1H,
N···H···O); 3.93 (s, 2H, CH2); −20.47 (t, 1H, JP,H = 14.2 Hz, IrH).
Preparation of [IrHCl{(PPh2(o-C6H4CO)(PPh2(o-C6H4CNNH2)-
H}] (10). To a THF solution of 1 (50 mg, 0.062 mmol) was added
hydrazine (1.8 μL, 0.062 mmol). Stirring during 90 min and
evaporation of the solvent gave an orange solid that was washed
with diethyl ether and vacuum-dried. Yield: 40 mg, 79%. IR (cm−1):
3175 (m), ν(NH); 2190 (m), ν(IrH); 1587 (s), ν(CO). Anal. Calc.
for C38H32ClIrN2OP2: C 55.51, H 3.92, N 3.41; found: C 56.03, H
31P{1H}NMR (CDCl3): δ 30.4 (d, JP,P = 7 Hz); 15.3 (d). 13C{1H}-
NMR (CDCl3): δ 243.3 (d, JP,C = 106 Hz, IrCO); 223.0 (d, JP,C
103 Hz, IrCN); 46.5 (s, CH2).
=
Preparation of [IrH(PPh2(o-C6H4CO))2L] (L = (H2NCH2C6H5 (3);
H2NC6H11 (4)). To a THF/H2O (1/1) suspension of 1 (50 mg, 0.062
mmol) was added the corresponding ligand (13.6 or 14.2 μL, 0.124
mmol). Stirring during 4 h and decantation gave pale yellow solids that
were washed with diethyl ether and vacuum-dried. Data for 3. Yield:
35 mg, 63%. IR (cm−1): 3310 (m), 3272 (w), ν(NH); 2031 (s),
ν(IrH); 1596 (s), 1560 (s), ν(CO). Anal. Calc. for C45H38IrNO2P2:
1
3.27, N 3.96. H NMR (THF-d8, 173 K): δ 14.16 (s, 1H, N···H···O);
3.21 (s, 2H, NH2); −19.11 (t, 1H, JP,H = 16.8 Hz, IrH). 31P{1H}NMR
(THF-d8, 173 K): δ 19.8 (s); 13.3 (s).
Preparation of cis-[IrCl(PPh2 (o-C6 H4 CO))(PPh2 (o-
C6H4CHNRC5H3R′N))] (R = R′ = H (11); R = CH3, R′ = H (12); R =
H, R′ = CH3 (13)). To a dichloromethane/methanol (1:1) solution of 1
(50 mg, 0.062 mmol) was added the corresponding ligand (0.062
mmol). Stirring during 24 h and evaporation of CH2Cl2 gave yellow
solids that were decanted, washed with methanol and vacuum-dried.
Data for 11. Yield 42 mg, 77%. IR (cm−1): 3273 (m), ν(NH); 1627
(s), ν(CO). Anal. Calc. for C43H33ClIrN2OP2·0.5CH2Cl2: C 56.43,
1
C 61.49, H 4.36, N 1.50; found: C 61.07, H 4.29, N 1.68. H NMR
(CDCl3): δ 3.43 (s, 2H, CH2); 2.61 (s, br, 1H, NH); 1.87 (s, br, 1H,
NH); −7.83 (dd, 1H, J(P,H)cis = 19.8 Hz; J(P,H)trans = 130.2 Hz, IrH).
31P{1H}NMR (CDCl3): δ 31.0 (d, JP,P = 4 Hz); 25.4 (d). 13C{1H}-
NMR (CDCl3): δ 239.0 (d, JP,C = 102 Hz, IrCO); 213.6 (s, IrC
O); 54.8 (s, CH2). Data for 4. Yield: 43 mg, 87%. IR (cm−1): 3309
(w), 3220 (w), ν(NH); 2050 (m), ν(IrH); 1609 (s), 1563(s), ν(C
O). Anal. Calc. for C44H42IrNO2P2·CH2Cl2: C, 56.54; H, 4.64; N,
1.47; found: C, 56.43; H, 4.62; N, 1.67. 1H NMR (CDCl3): δ 3.09 (s,
br, 2H, NH); 2.92 − 0.25 (m, 11H, cyclohexyl); −7.98 (dd, 1H,
J(P,H)cis = 19.7 Hz; J(P,H)trans = 130.1 Hz, IrH). 31P{1H}NMR (CDCl3):
δ 30.1 (d, JP,P = 5 Hz); 24.7 (d). 13C{1H}NMR (CDCl3): δ 238.7 (d,
JP,C = 103 Hz, IrCO); 214.0 (s, IrCO).
1
H 3.70, N 3.03; found C 56.00, H 3.79, N 3.16. H NMR (CDCl3):
δ 6.07 (m, 1H, IrCH); 5.29 (d, 1H, JP,H = 7.9 Hz, NH). 31P{1H} NMR
(CDCl3): δ 23.8 (d, JP,P = 4 Hz); 17.4 (d). 13C{1H} NMR (CDCl3):
δ 216.3 (s, IrCO); 67.4 (d, JP,C = 86 Hz, IrCH). Data for 12.
Yield 35 mg, 63%. IR (cm−1): 1616 (s), ν(CO). Anal. Calc. for
C44H35ClIrN2OP2·0.75CH2Cl2: C 55.93, H 3.83, N 2.92; found C
55.89, H 3.85, N 2.89. 1H NMR (CDCl3): δ 5.86 (d, 1H, JP,H = 5.7 Hz,
IrCH); 3.14 (s, 3H, CH3). 31P{1H} NMR (CDCl3): δ 24.0 (d, JP,P = 4
Hz); 16.4 (d). 13C{1H} NMR (CDCl3): δ 217.9 (s, IrCO); 75.2 (d,
JP,C = 83 Hz, IrCH); 37.5 (s, CH3). Data for 13. Yield 40 mg, 72%. IR
(cm−1): 3420 (w), ν(NH); 1615(s), ν(CO). Anal. Calc. for
C44H35ClIrN2OP2·0.5CH2Cl2: C 56.87, H 3.86, N 2.98; found C
56.60, H 3.78, N 3.31. 1H NMR (CDCl3): δ 6.11 (d, 1H, JP,H = 5.3 Hz,
IrCH); 5.78 (m, 1H, NH); 1.87 (s, 3H, CH3). 31P{1H} NMR
(CDCl3): δ 23.8 (d, JP,P = 4 Hz); 16.9 (d). 13C{1H} NMR (CDCl3):
δ 216.4 (d, JP,C = 5 Hz, IrCO); 66.6 (d, JP,C = 87 Hz, IrCH); 18.1 (s,
CH3).
Preparation of [IrH(PPh2(o-C6H4CO))2(NH(CH3)2)] (5). To a
THF/H2O (1/1) suspension of 1 (50 mg, 0.062 mmol) at 0 °C was
added dimethylamine in 2 M THF solution (31 μL, 0.062 mmol)
whereupon a solution was obtained. Stirring during 5 min and
evaporation of THF gave a pale yellow solid that was decanted,
washed with diethyl ether, and vacuum-dried. Yield: 27 mg, 52%. IR
(cm−1): 3282 (w) ν(NH); 2038 (m), ν(IrH); 1606 (s), 1564 (s),
ν(CO). Anal. Calc. for C40H36IrNO2P2·2H2O: C 56.33, H 4.73, N
1
1.64; found: C 56.00, H 4.56, N 1.48. H NMR (CDCl3): δ 2.35 (d,
3H, JH,H = 5.8 Hz, CH3); 2.24 (d, 3H, JH,H = 5.8 Hz, CH3); 1.79 (m,
1H, NH); −7.70 (dd, 1H, J(P,H)cis = 19.8 Hz; J(P,H)trans = 131.6 Hz,
IrH). 31P{1H}NMR (CDCl3): δ 30.6 (d, JP,P = 3 Hz); 24.9 (d).
13C{1H}NMR (CDCl3): δ 234.8 (d, JP,C = 106 Hz, IrCO); 212.4
Preparation of trans-[IrCl{(PPh2(o-C6H4CO))(PPh2(o-
C6H4CHNRC5H3R′N))] (R = R′ = H (14); R = CH3, R′ = H (15); R =
H, R′ = CH3 (16)). To a methanol suspension of 1 (50 mg, 0.062
mmol) was added the corresponding ligand (0.062 mmol). The
suspension was refluxed whereupon the formation of a yellow solution
occurs, followed by the appearance of a yellow precipitate. After 4 h
reflux and cooling, the solids were decanted, washed with methanol,
and vacuum-dried. Data for 14. Yield 28 mg, 52%. IR (cm−1): 3315
(w), ν(NH); 1621 (s), ν(CO). Anal. Calc. for C43H33ClIrN2-
OP2·2CH3OH: C 57.05, H 4.36, N 2.96; found C 56.76, H 4.01, N
3.55. 1H NMR (CDCl3): δ 4.61 (dd, 1H, JP,H = 4.3 Hz, JP,H = 10.4 Hz,
(m, IrCO); 49.8 (s, CH3); 47.9 (s, CH3).
Preparation of [IrCl(PPh2(o-C6H4CO))2L] (L = H2NCH2C6H5 (6);
H2NC6H11 (7); H2NCH3 (8); HN(CH3)2 (9)). A CCl4 suspension of the
corresponding [IrH(PPh2(o-C6H4CO))2L] (0.034 mmol) was refluxed
during 1 h until a solution was obtained. The evaporation of the
solvent gave pale yellow solids that were washed with diethyl ether and
vacuum-dried. Data for 6. Yield: 18 mg, 58%. IR (cm−1): 3289 (w),
3173 (w), ν(NH); 1620 (s), 1575 (s), ν(CO). Anal. Calc. for
C45H37ClIrNO2P2.0.5CH2Cl2: C 57.44, H 3.98, N 1.46; found C
IrCH); 4.09 (s, br, 1H, NH). 31P{1H} NMR (CDCl3): δ 29.2 (d, JP,P
=
1
57.67, H 4.06, N 1.59. H NMR (CDCl3): 5.73 (s, br, 1H, NH), 3.54
390 Hz); 23.4 (d). 13C{1H} NMR (CDCl3): δ 218.6 (s, IrCO); 45.1
(s, IrCH). Data for 15. Yield 34 mg, 62%. IR (cm−1): 1607 (s), ν(C
O). Anal. Calc. for C44H35ClIrN2OP2·2CH3OH: C 57.46, H 4.51, N
(m, 1H, CH2), 3.24 (s, br, 1H, NH), 2.38 (m, 1H, CH2). 31P{1H}-
NMR (CDCl3): δ 23.2 (d, JP,P = 5 Hz); 9.3 (d). 13C{1H}NMR
(CDCl3): δ 231.0 (d, JP,C = 108 Hz, IrCO); 208.4 (d, JP,C = 7 Hz,
IrCO); 49.5 (s, CH2). Data for 7. Yield: 30 mg, 99%. IR (cm−1):
3292 (w), 3167 (w), ν(NH); 1622 (s), ν(CO). Anal. Calc. for
1
2.91; found C 57.11, H 4.21, N 2.83. H NMR (CDCl3): δ 4.27 (dd,
1H, JP,H = 4.1 Hz, JP,H = 10.7 Hz, IrCH); 2.26 (s, 3H, CH3). 31P{1H}
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Inorganic Chemistry
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Table 3. Crystal Data and Refinement Data for 6, 9, 13, and 14
Crystal Data
identification code
6
9
13
14
CCDC-830884
CCDC-830885
CCDC-830886
[C44H36ClN2OP2Ir]·C4H10O
972.46
CCDC-830887
empirical formula
formula wt
crystal sys.
space group
a/Å
[C45H37ClNO2P2Ir]·1/2C4H10O [C40H35ClNO2P2Ir]
[C43H34ClN2OP2Ir]·CH2Cl2
969.24
950.41
851.28
monoclinic
C2/c
monoclinic
C2/c
triclinic
monoclinic
P2(1)/c
P1
̅
27.130(2)
19.595(1)
19.595(1)
26.411(3)
19.349(2)
19.978(2)
11.0825(7)
13.0297(8)
15.097(1)
89.345(1)
78.796(1)
78.253(1)
2092.8(2)
2
10.355(1)
b/Å
16.157(1)
c/Å
24.241(2)
α /deg
β /deg
123.846(1)
123.279(2)
100.505(1)
γ /deg
V/Å3
8651.5(8)
8535(2)
3987.8(5)
Z
8
8
4
Dc /g/cm3
1.459
1.325
1.543
1.614
−1
μ(Mo−Kα) /mm
F(000)
3.261
3.296
3.372
3.667
3800
3376
976
1920
θ range/deg
1.38 to 25
−32,−23,−21 to 32,20,23
32960
1.40 to 26.37
−32,−23,−24 to 23,24,24
35824
1.91 to 25
−13,−15,−17 to 13,15,17
21188
1.52 to 25
index ranges
−11,−19,−28 to 12,19,26
30207
reflections collected
unique reflections [R(int)]
completeness to θ
data/restraints/params
R1 (reflns obsd) [I > 2σ(I)]
7611 [R(int) = 0.052]
99.9%
8706 [R(int) = 0.0393]
99.7%
7349 [R(int) = 0.0284]
99.7%
7031 [R(int) = 0.1311]
99.9%
7611/4/469
0.0379 (4636)
0.1291
8706/0/424
0.0473 (5768)
0.2568
7349/0/505
0.0212 (6539)
0.0512
7031/0/478
0.0469(3976)
0.1098
a
b
wR2 (all data)
largest diff. peak and hole/e Å−3 1.124 and −0.482
R1 = ∑||Fo| − |Fc||/∑|Fo|. wR2 = {∑[w(Fo − Fc2)2]/∑[w(Fo )2]}.
1.867 and −0.794
2
0.935 and −0.815
1.468 and −1.992
a
b
2
NMR (CDCl3): δ 27.6 (d, JP,P = 391 Hz); 23.3 (d). 13C{1H} NMR
(CDCl3): δ 219.3 (d, JP,C = 4 Hz, IrCO); 53.4 (s, IrCH); 34.5 (s,
CH3). Data for 16. Yield 34 mg, 62%. IR (cm−1): 3408 (s), ν(NH);
1609(s), ν(CO). Anal. Calc. for C44H35ClIrN2OP2·CH3OH: C
X-ray Structure Determination of [C45H37ClNO2P2Ir]·1/
2C4H10O (6), [C40H35ClNO2P2Ir] (9), [C44H36ClN2OP2Ir]·C4H10O
(13), and [C43H34ClN2OP2Ir]·CH2Cl2 (14). Suitable crystals for X-ray
experiments were obtained by slow diffusion of diethyl ether into
dichloromethane (6, 9, and 14) or chloroform (13) solutions. Data were
collected on a Bruker Smart CCD diffractometer, with graphite-
1
58.15, H 4.23, N 3.01; found C 58.07, H 4.24, N 2.97. H NMR
(CDCl3): δ 4.60 (dd, 1H, JP,H = 4.3 Hz, JP,H = 10.3 Hz, CH); 3.83 (s,
1H, NH); 1.65 (s, 3H, CH3). 31P{1H} NMR (CDCl3): δ 32.7 (d, JP,P
=
monochromated Mo−K (λ = 0.71073) radiation, operating at 50 kV
α
392 Hz); 27.9 (d). 13C{1H} NMR (CDCl3): δ 218.4 (d, JP,C = 4 Hz,
IrCO), 44.4 (s, IrCH); 17.6 (s, CH3).
and 20 or 30 mA. A summary of the fundamental crystal data and
refinement data are given in Table 3. In all cases data were collected over a
hemisphere of the reciprocal space by combination of three exposure sets.
Each frame exposure time was of 10 s or 20 s, covering 0.3° in ω. The cell
parameters were determined and refined by a least-squares fit of all
reflections collected. The first 100 frames were recollected at the end of the
data collection to monitor crystal decay. No appreciable decay was ob-
served. A semiempirical absorption correction was applied for 6, 9, and 13.
The structures of all the compounds were solved by direct methods
and refined by full-matrix least-squares on F2 (SHELXS-97).26 All
nonhydrogen atoms have been refined anisotropically, except the solvent
molecules for 6, which have been refined isotropically and with geometrical
restraints. The hydrogen atoms were included in calculated positions and
refined riding on their respective carbon atoms with the thermal
parameters related to the bonded atom, except the H atoms bonded to
N atoms for all compounds and the hydrogen atoms bonded to C20 for 14
and 13, which were located in a final Fourier difference synthesis and
included with fixed isotropic factors and coordinates for 9, 14, and 13
while for 6 refined riding. The final R and Rw are shown in Table 3.
Preparation of [Ir(CO)(PPh2(o-C6H4))(PPh2(o-C6H4CHNHC-
5H4N))]ClO4 (17). To a CH2Cl2 solution of 11 (50 mg, 0.057 mmol)
was added AgClO4 (12 mg, 0.057 mmol). After being stirred for
30 min the silver salts were filtered and the solvent was evaporated to
give a yellow solid that was washed with diethyl ether and vacuum-
dried. Yield 35 mg, 63%. IR (cm−1): 3324 (m), ν(NH); 2041 (s),
ν(CO). ΛM (ohm−1 cm2 mol−1): 134 (acetone). Anal. Calc. for
C43H43IrN2OP2ClO4·0.25CH2Cl2: C 53.58, H 3.59, N 2.89; found C
1
53.42, H 3.54, N 3.03. Data for cis-17. H NMR (CDCl3): δ 6.49 (s,
1H, IrCH); 6.10 (m, 1H, NH). 31P{1H} NMR (CDCl3): δ 23.5 (d,
JP,P = 7 Hz); −65.2 (d). 13C{1H} NMR (CDCl3): δ 168.4 (t, JP,C
=
5 Hz, IrCO); 51.8 (d, JP,C = 71 Hz, IrCH). Data for trans-17.
31P{1H} NMR (CDCl3): δ 31.4 (d, JP,P = 342 Hz); −65.7 (d). 13C{1H}
NMR (CDCl3): δ 170.4 (t, JP,C = 7 Hz, IrCO); 47.1 (s, IrCH).
Preparation of [Ir(CO)(PPh2(o-C6H4))(PPh2(o-C6H4CHN(CH3)-
C5H4N))]BF4 (18). To a CH2Cl2 solution of 12 (50 mg, 0.056 mmol)
was added Et3OBF4 (11 mg, 0.056 mmol). Stirring during 30 min and
evaporation of the solvent gave a yellow solid that was washed with
diethyl ether and vacuum-dried. Yield 45 mg, 86%. IR (cm−1): 2045
(s), ν(CO). ΛM (ohm−1 cm2 mol−1): 132 (acetone). Anal. Calc. for
C43H43IrN2OP2BF4·0.5CH2Cl2: C 53.41, H 3.61, N 2.86; found C
53.48, H 3.91, N 3.09. Data for cis-18. 1H NMR (CDCl3): δ 6.16 (m,
1H, IrCH); 3.27 (s, 3H, CH3). 31P{1H} NMR (CDCl3): δ 22.5 (s);
−66.2 (s). 13C{1H} NMR (CDCl3): δ 168.8 (t, JP,C = 6 Hz, IrCO];
60.7 (d, JP,C = 70 Hz, IrCH); 37.4 (d, JP,C = 4 Hz, CH3). Data for
trans-18. 1H NMR (CDCl3): 3.33 (s, 3H, CH3). 31P{1H} NMR
(CDCl3): δ 30.5 (d, JP,P = 337 Hz); −65.9 (d). 13C{1H} NMR
(CDCl3): δ 56.6 (s, IrCH); 37.0 (s, CH3).
ASSOCIATED CONTENT
* Supporting Information
■
S
Crystallographic data file of complexes 6, 9, 13, and 14 in CIF
format. This material is available free of charge via the Internet
at http://pubs.acs.org.
AUTHOR INFORMATION
Corresponding Author
*E-mail: mariaangeles.garralda@ehu.es.
■
1767
dx.doi.org/10.1021/ic202065d | Inorg. Chem. 2012, 51, 1760−1768

Inorganic Chemistry
Article
(15) (a) Uson
́
, R.; Oro, L. A.; Carmona, D.; Esteban, M. J. Organomet.
ACKNOWLEDGMENTS
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(CTQ2008-2967/BQU), Gobierno Vasco, Universidad del Paıs
́
́
Vasco, and Diputacion
acknowledged.
́
Foral de Gipuzkoa are gratefully
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