Reactivity of hydridoirida-β-diketones with bases: The selective formation of new di-μ-acyl-μ-hydridodiiridium(III) or dihydridoirida- β-diketone complexes and heterometallic Ir(III)-Rh(I) derivatives

Article abstract of DOI:10.1039/b803488e

The hydridoirida-β-diketone [IrHCl{(PPh₂(o-C ₆H₄CO))₂H}] (1a) reacts with bases such as KOH or NaHCO₃ in methanol to undergo dehydrodechlorination and acyl-bridge formation affording [Ir₂H₂(PPh ₂(o-C₆H₄CO))₂(μ-PPh ₂(o-C₆H₄CO))₂] (2) with two acylphosphine chelate-bridging ligands, in a head-to-tail disposition, and terminal hydrides. The acyl bridges can be broken by pyridine, PPh₃, CO or dimethylsulfoxide affording selectively mononuclear diacylhydrido neutral derivatives [IrH(PPh₂(o-C₆H₄CO))₂L] (3-6). 1a reacts with KOH or NaHCO₃ in refluxing methanol to afford a novel dihydridoirida-β-diketone [IrH₂{(PPh₂(o-C ₆H₄CO))₂H}] (7), via dehydrodechlorination to afford 2, which then undergoes hydrogenation and protonation. The reaction of 1a with NEt₃ affords 2 and [NHEt₃]Cl. Further reaction affords [Ir₂(μ-H){μ-PPh₂(o-C₆H ₄CO)}₂(PPh₂(o-C₆H ₄CO))₂]⁺ (8), with two acylphosphine chelate-bridging ligands and a bridging hydride. Neutral or cationic hydridoirida-β-diketone complexes react with [Rh(cod)(OMe)]₂ (cod = 1,5-cyclooctadiene) to afford hydridoirida-β-diketonaterhodium(i) complexes [IrHCl(μ-PPh₂(o-C₆H₄CO)) ₂Rh(cod)] (9) or [IrHL(μ-PPh₂(o-C₆H ₄CO))₂Rh(cod)]ClO₄ (L = py, 10; CO, 11), respectively that isomerise to the thermodynamically stable isomers of [IrCl(PPh₂(o-C₆H₄CO))(μ-H))(μ-PPh ₂(o-C₆H₄CO))Rh(cod)] (12) or [Ir(py)(PPh ₂(o-C₆H₄CO))(μ-H))(μ-PPh ₂(o-C₆H₄CO))Rh(cod)]ClO₄ (13). The reaction of 7 with [Rh(cod)(OMe)]₂ affords [Ir(PPh ₂(o-C₆H₄CO))₂(μ-H) ₂Rh(cod)] (14). All the complexes were fully characterised spectroscopically. Single-crystal X-ray diffraction analysis was performed on 2, 4, 7, [8]ClO₄ and 9.

Full text of DOI:10.1039/b803488e

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PAPER
www.rsc.org/dalton | Dalton Transactions
Reactivity of hydridoirida-b-diketones with bases: the selective formation of
new di-l-acyl-l-hydridodiiridium(III) or dihydridoirida-b-diketone complexes
and heterometallic Ir(III)–Rh(I) derivatives†
Francisco Acha,a Roberto Ciganda,a Mar´ıa A. Garralda,*a Ricardo Herna´ndez,a Lourdes Ibarlucea,a
Elena Pinillab and M. Rosario Torresb
Received 28th February 2008, Accepted 2nd May 2008
First published as an Advance Article on the web 18th June 2008
DOI: 10.1039/b803488e
The hydridoirida-b-diketone [IrHCl{(PPh2(o-C6H4CO))2H}] (1a) reacts with bases such as KOH or
NaHCO3 in methanol to undergo dehydrodechlorination and acyl-bridge formation affording
[Ir2H2(PPh2(o-C6H4CO))2(l-PPh2(o-C6H4CO))2] (2) with two acylphosphine chelate-bridging ligands, in
a head-to-tail disposition, and terminal hydrides. The acyl bridges can be broken by pyridine, PPh3, CO
or dimethylsulfoxide affording selectively mononuclear diacylhydrido neutral derivatives
[IrH(PPh2(o-C6H4CO))2L] (3–6). 1a reacts with KOH or NaHCO3 in refluxing methanol to afford a
novel dihydridoirida-b-diketone [IrH2{(PPh2(o-C6H4CO))2H}] (7), via dehydrodechlorination to afford
2, which then undergoes hydrogenation and protonation. The reaction of 1a with NEt3 affords 2 and
[NHEt3]Cl. Further reaction affords [Ir2(l-H){l-PPh2(o-C6H4CO)}2(PPh2(o-C6H4CO))2]+ (8), with two
acylphosphine chelate-bridging ligands and a bridging hydride. Neutral or cationic
hydridoirida-b-diketone complexes react with [Rh(cod)(OMe)]2 (cod = 1,5-cyclooctadiene) to afford
hydridoirida-b-diketonaterhodium(I) complexes [IrHCl(l-PPh2(o-C6H4CO))2Rh(cod)] (9) or
[IrHL(l-PPh2(o-C6H4CO))2Rh(cod)]ClO4 (L = py, 10; CO, 11), respectively that isomerise to the
thermodynamically stable isomers of [IrCl(PPh2(o-C6H4CO))(l-H))(l-PPh2(o-C6H4CO))Rh(cod)] (12)
or [Ir(py)(PPh2(o-C6H4CO))(l-H))(l-PPh2(o-C6H4CO))Rh(cod)]ClO4 (13). The reaction of 7 with
[Rh(cod)(OMe)]2 affords [Ir(PPh2(o-C6H4CO))2(l-H)2Rh(cod)] (14). All the complexes were fully
characterised spectroscopically. Single-crystal X-ray diffraction analysis was performed on 2, 4, 7,
[8]ClO4 and 9.
of platina-b-diketones. Depending on the base used, neutral
Introduction
complexes [LClPt(l-COMe)2Pt{(COMe)2H}]2 or anionic deriva-
tives [{Cl2Pt(l-COMe)2Pt[(COMe)2H]}2]2−, of the platinum-blue
Metalla-b-diketones can be considered as acylhydroxycarbene
structural type, were obtained.5,6 The hydridoirida-b-diketone
[IrHCl{(PPh2(o-C6H4CO))2H}] (1a) prepared by the reaction of
[IrHCl(PPh2(o-C6H4CO))(cod)] (cod = 1,5-cyclooctadiene) with
PPh2(o-C6H4CHO) in protic solvents is remarkably stable and re-
quires the use of halide scavengers to afford mono- [IrH{(PPh2(o-
C6H4CO))2H}L]+, or dinuclear [{IrH((PPh2(o-C6H4CO))2H)}2(l-
Cl)]+ cationic hydridoirida-b-diketones. These complexes may un-
dergo deprotonation reactions to afford neutral diacylhydridoirid-
ium(III) species or a dinuclear hydridotris-l-acyldiiridium(III)
complex, respectively.7,8 The ability of PPh2(o-C6H4CHO), coor-
dinated to tungsten or technetium, to undergo carbon–carbon
coupling of two ligands and thus affording new dioxyl-coordinated
derivatives has been reported.9
Here, we report the reactions of the hydridoirida-b-diketone
[IrHCl{(PPh2(o-C6H4CO))2H}] (1a) with bases such as NEt3,
NaHCO3 or KOH in methanol that undergo dehydrodechlori-
nation and afford dinuclear dihydridodi-l-acyl- or di-l-acyl-l-
hydridodiiridium(III) complexes or form a new dihydridoirida-
b-diketone depending on the reaction conditions. The reac-
tion of neutral or cationic hydridoirida-b-diketone complexes
with [Rh(cod)(OMe)]2 that affords the previously unknown
hydridoirida-b-diketonaterhodium(I) complexes are also reported.
complexes stabilised by intramolecular hydrogen bonds between
the acyl and hydroxycarbene moieties. Lukehart’s metalla-b-
diketones (M = Mo, W, Mn, Re, Fe, Os)1 can be synthesised by
the protonation of diacylmetalate anions [LxM(COR)(CORꢀ)]−.
These metalla-b-diketones can be used to afford heterobinuclear-
metal complexes of metalla-b-diketonates with two bridging acyl
ligands when deprotonated by transition metal complexes having
basic ligands. (Metalla-b-diketonate)BF2 complexes have been
reported to allow the carbon–carbon bond formation between
the acyl carbon bonds.2 Platina- and irida-b-diketones have been
reported more recently.3,4 Dinuclear platina-b-diketones [Pt2(l-
Cl)2{(COR)2H}2], obtained by the reaction of hexachloropla-
tinic acid with alkynes, react with amines or strong bases
to afford the formation of platina-b-diketonates derivatives
aFacultad de Qu´ımica de San Sebastia´n, Universidad del Pa´ıs Vasco, Apdo.
1072, 20080 San Sebastia´n, Spain. E-mail: mariaangeles.garralda@ehu.es
bDepartamento de Qu´ımica Inorga´nica, Laboratorio de Difraccio´n de Rayos
X, Facultad de Ciencias Qu´ımicas, Universidad Complutense, 28040 Madrid,
Spain
† CCDC reference numbers 679480 (2), 679481 ([8]ClO4), 679482 (4),
679483 (7), 679484 (9). For crystallographic data in CIF or other electronic
format see DOI: 10.1039/b803488e
4602 | Dalton Trans., 2008, 4602–4611
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©

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saturation by acyl-bridge formation. Five-coordinated acyl irid-
ium(III) complexes such as [IrCl2(COR)(PPh3)2] are well known.16
The reaction comprises a change in the stereochemistry at the
iridium atom. In the starting material the hydride is trans to the
lower trans influence ligand, chloride, whereas in 2 the hydride is
trans to phosphorus. This disposition appears to be the most stable
when the hydrogen bonding in the starting acyl hydroxycarbene
moiety is lost. The deprotonation of a related cationic hydridoacyl
hydroxycarbene complex is followed by isomerisation affording a
similar stereochemistry at the iridium atom.7
Complex 2 reacts with donor ligands such as pyridine or
triphenylphosphine or with small molecules such as carbon
monoxide or dimethylsulfoxide to undergo acyl-bridge splitting
and the formation of mononuclear diacylhydrido neutral deriva-
tives [IrH(PPh2(o-C6H4CO))2L] 3–6, as shown in Scheme 1. In
this reaction the stereochemistry is maintained, so that all the
complexes obtained contain the hydrido ligand and one acyl group
trans to the phosphorus atoms and the monodentate ligand is
trans to the other acyl group, as shown by the NMR data. All
the complexes show the expected features for hydrides trans to
phosphorus and for terminal acyl groups, one of which is trans to
phosphorus. The crystal structure of 4 confirms the spectroscopic
findings (vide infra).† Complex 6 was identified only spectroscopi-
cally because it has been obtained previously by deprotonation of
the cationic [IrH{(PPh2(o-C6H4CO))2H}(CO)]ClO4 with DMSO
followed by isomerisation.7 Attempts to obtain complexes 3–5
by deprotonation reactions on cationic species was not selective
and led only to mixtures of the corresponding isomers with the
hydride trans to phosphine and those with the hydride trans to L,
as previously observed for L = DMSO.7 Complex 2 also reacts
with HCl gas in MeOH to afford 1a as the main product along
with other unidentified species.
Results and discussion
The reaction of 1a with bases such as KOH or NaHCO3 in
methanol leads to the deprotonation of the acylhydroxycarbene
fragment along with the loss of chloride to afford the dinuclear
neutral complex [Ir2H2(PPh2(o-C6H4CO))2(l-PPh2(o-C6H4CO))2]
(2) (see Scheme 1), as indicated by IR, NMR and FAB measure-
ments. The IR spectrum shows a sharp absorption at 2042 cm−1
due to t(Ir–H), a strong absorption due to terminal acyl groups
at 1603 cm−1 and a strong absorption at 1504 cm−1 that is
markedly displaced toward lower wavenumbers, due to bridging
1
acyl groups.10 The 13C{ H} NMR spectrum contains a singlet
in the low-field region (203.8 ppm) due to the terminal acyl
groups and a doublet at a much lower field (274.3 ppm) due to
bridging acyl groups, with marked carbenoid character,10–13 trans
to phosphorus (2J(P, C) = 103 Hz). The 1H NMR spectrum shows
a single resonance for the hydrides as a double doublet of doublets
due to coupling with a trans phosphorus atom (2J(P, H)trans
=
125.2 Hz), a cis phosphorus atom (2J(P, H)cis = 21.9 Hz) and a
long-range coupling (5J(P, H) = 5.0 Hz). Accordingly, the 31P{ H}
1
NMR spectrum contains two singlets due to two non-equivalent
2
phosphorus atoms mutually cis with an unobservable J(P, P),
and the 31P NMR spectrum indicates that the doublet at higher
field (22.8 ppm) corresponds to the phosphorus atoms trans to the
hydride. All the data point to the formation of a single-dinuclear
species with two equivalent acylphosphines behaving as chelate-
bridging ligands in a head-to-tail disposition. Their phosphorus
atoms are trans to the equivalent hydrides and the bridging carbon
atoms are trans to the phosphorus atoms of the terminal chelating
acylphosphine groups. The exact disposition of the hydrides
cannot be deduced from the data and the cisoid fashion was
confirmed from an X-ray diffraction study (vide infra). Though
acyls are well known as bridging ligands towards transition metals,
their behaviour as such in iridium homodinuclear complexes is
scarce.8,14 The acylphosphine chelating ligand o-PPh2(C6H4CO)
has also been reported to behave as an acyl-bridging ligand in
ruthenium or osmium clusters.15
Acyl-hydride complexes are believed to be involved in a large
number of catalytic reactions including olefin hydroformylation
to produce aldehydes or aldehyde decarbonylation to produce
RH.17 Accordingly, frequent stoichiometric reactions for acyl
hydride metal complexes undergo reductive elimination to produce
aldehydes or aldehyde decarbonylation.18,19 Unexpectedly, the
reaction of 1a with KOH or NaHCO3 in refluxing methanol
leads to the exchange of chloride by hydride to afford a new
dihydridoirida-b-diketone [IrH2{(PPh2(o-C6H4CO))2H}] (7). The
reaction of 2 with KOH or NaHCO3 in refluxing methanol also
leads to the formation of 7, as shown in Scheme 1, and we have
observed that complex 2 is an intermediate in the transformation
of 1a into 7. During the course of the reaction, the starting
yellow solid (1a) changes to brown (2) and then back to yellow
(7). These assignments were confirmed by NMR spectroscopy. It
appears now that under basic conditions the acyl hydroxycarbene
moiety can be firstly broken, and then reformed at higher
temperatures with concomitant formation of a trans-dihydride
derivative, characterised by a sharp resonance at −8.76 ppm
2
1
{t, J(P, H) = 18.1 Hz} in the H NMR spectrum. It is well
known that metal hydrides can be readily formed in refluxing basic
alcoholic media via alkoxide coordination followed by b-H transfer
and are active catalysts in the transfer hydrogenation of ketones.20
A labelling experiment confirms that in our case the solvent is the
source of the second hydride. When the reaction of 2 with KOH is
performed in refluxing CD3OD, the solid obtained shows a broad
resonance at −8.64 ppm {t, br, 2J(P, H) = 18.7 Hz} in the 1H NMR
Scheme 1
The transformation of 1a into 2 may well occur via a de-
hydrodechlorination step to afford a penta-coordinated Ir(III)
species, [IrH(PPh2(o-C6H4CO))2], which attains coordinative
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spectrum. The broadness of the signal showing otherwise similar
characteristics to those of 7, indicates that the product obtained
in CD3OD is a deuterated species [7D] containing hydrogen trans
to the deuterium originated from the solvent. Accordingly, we
believe that at higher temperatures, 7 can be obtained via the
transient formation of a pentacoordinated Ir(III) intermediate that
can coordinate the methoxide. The b-H transfer with the liberation
of formaldehyde affording a dihydride,19 and the protonation of
the diacyl moiety may afford complex 7. Complex 7 reacts with
HCl gas in refluxing MeOH to afford 1a as the main product along
with other unidentified species.
with trans phosphorus atoms at 239.9 ppm (2J(P, C)trans = 95 Hz).
This resonance appears at higher field than that observed for
the neutral species 2 (274.3 ppm) and close to that observed
for the mononuclear species 3–5 (226–237 ppm) and suggests
low, if any, carbenoid character in these bridging acyl groups. In
order to obtain crystals containing 8 that were suitable for X-ray
diffraction, we isolated the corresponding compound [8]ClO4 by
the reaction of [8]Cl with AgClO4.
We observed that by using NEt3 as a deprotonating agent,
complete dehydrodechlorination and loss of half of the hydrides
occur to afford a cationic-dinuclear species containing a hydride
bridge. The mechanism of this reaction involves dehydrodechlo-
rination as the first step to afford the dinuclear hydride 2 and
[NHEt3]Cl. Intermolecular N–H · · · H–M interactions, which can
result in H2 evolution, have been reported.22 Therefore, we believe
that the interaction of 2 with the soft acid Et3NH+ can promote the
evolution of H2 to afford the cationic species 8 containing a hydride
bridge. Complex 8 is rather unreactive at room temperature. It
remained unchanged in attempted reactions with CO, pyridine,
PPh3 or dimethylsulfoxide. The reaction of [8]ClO4 with HCl
results in anion exchange with formation of [8]Cl, as shown in
Scheme 2. [8]Cl reacts with HCl gas in refluxing MeOH to afford
a complex mixture of unidentified products.
According to the NMR data, the two acylphosphine fragments
1
present in 7 are equivalent. The 31P{ H} NMR spectrum shows a
1
singlet at 31.9 ppm, and the 13C{ H} NMR spectrum contains a
doublet at 259.3 ppm, in the expected range for Ir(III) species with
2
acyl(hydroxycarbene) character.7,21 The large J(P, C) of 99 Hz
confirms the presence of acyl groups trans to phosphorus atoms.
The chemical shift of the enolic proton in 7, 22.66 ppm, is very close
to that of the parent irida-b-diketone 1a.4 An X-ray diffraction
study confirms the structure depicted in Scheme 1.
When using NEt3 as a proton abstractor, 1a reacts slowly at
room temperature to form complex 2, which transforms into a new
complex [Ir2(l-H){l-PPh2(o-C6H4CO)}2(PPh2(o-C6H4CO))2]+ 8,
as shown in Scheme 2. In this case, the formation of a mixture
of complexes 2 and 8 is observed until the transformation into 8
is completed, and the formation of [NHEt3]Cl is also observed.
By performing the reaction in refluxing MeOH compound [8]Cl
can be obtained more readily. IR, conductivity and FAB mea-
surements confirm the ionic dinuclear nature of complex 8. The
IR spectrum shows two strong absorptions due to terminal and
bridging-acyl groups at 1624 and 1522 cm−1, respectively. The
presence of a triplet of triplets in the 1H NMR spectrum suggests
the presence of a bridging hydride trans to two phosphorus atoms
(2J(P, H)trans = 55.6 Hz) and cis to another two phosphorus
atoms (2J(P, H)cis = 12.7 Hz). The 31P NMR spectrum contains
a doublet at 29.8 ppm due to two equivalent phosphorus atoms
trans to hydride and a singlet at 11.4 ppm due to two equivalent
As shown in Scheme 3(i), neutral or cationic hydridoirida-
b-diketone complexes 1a, 1b or 1c can also be deprotonated
by transition metal complexes having basic ligands such as
[Rh(cod)(OMe)]2 to afford the previously unknown hydridoirida-
b-diketonaterhodium(I) complexes 9–11. In the corresponding IR
spectra only a strong absorption due to the bridging acyl groups
1
at ca. 1520 cm−1 is observed. The 13C{ H} NMR spectra contain
only a doublet due to equivalent bridging acyl groups trans to
phosphorus (2J(P, C) = ca. 90 Hz) in the 258–245 ppm range, as in
the starting hydridohydroxycarbene complexes,4,7 and a doublet at
ca. 75 ppm due to equivalent olefinic groups bonded to rhodium.
The 1H NMR spectra contain triplets due to the iridium-bonded
hydrides cis to two phosphorus atoms and a single resonance due
to the olefinic groups bonded to the rhodium atom.
2
phosphorus atoms cis to hydride, the J(P, P) coupling constant
1
being unobservable. In the 13C{ H} NMR spectrum the terminal
acyl groups, being equivalent, appear as a singlet at 200.0 ppm
and the bridging-acyl groups appear as a doublet due to coupling
Scheme 3
The hydridoirida-b-diketonate rhodium(I) complexes 9 and
10 isomerise in refluxing methanol to form complexes 12 and
13, containing hydride and acyl bridging groups, as shown in
Scheme 3(ii). In the IR spectra absorptions due to terminal
and bridging acyl groups are observed. The 31P NMR spectra
Scheme 2
4604 | Dalton Trans., 2008, 4602–4611
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contain two resonances due to non-equivalent phosphorus atoms,
of the terminal acyl group (C20 or C39) is trans to PPh3 in 4 or to
the oxygen atom of the bridging acyl groups (O4 or O1) in 2 and
in [8]ClO4.
In the mononuclear complex 4, the distances comprising the
chelate ligands are within the expected ranges.7,23 According to
the similar structural trans influence of the hydride and the acyl
ligands,24 equivalent Ir–P distances could be expected. This is
1
of which one is trans to the hydride. The 13C{ H} NMR and
1H NMR spectra confirm the presence of bridging and terminal
acyl groups and also the non-equivalence of the olefinic groups
bonded to the rhodium atom. The hydride resonance is a doublet
of triplets due to the hydride being trans to one phosphorus atom,
cis to another phosphorus atom and bonded to the rhodium
atom. It thus appears that the formation of the hydridoirida-
b-diketonate species is kinetically favoured while the species
containing a bridging hydride ligand is the thermodynamically
favoured isomer. In line with this observation, complex 7 reacts
with [Rh(cod)(OMe)]2 to afford the dinuclear complex 14, with
two terminal acyl groups and two bridging hydrides, cis to
mutually trans phosphorus atoms, as indicated by the NMR
spectra (see Scheme 3(iii)). We therefore conclude that in these
Rh–Ir heterobinuclear complexes the hydrides appear to be more
suitable than the acyl groups acting as bridging ligands.
˚
found for the Ir–P1 and Ir–P2 distances, average of 2.355(2) A,
˚
which are shorter than the Ir–P3 distance 2.385(2) A, P3 belonging
to PPh3 while P1 and P2 are involved in chelate formation. It is
most likely that this feature is responsible for the differences ob-
=
served. The Ir–C(acyl) bond distances are similar and the C O dis-
tances are also equal. Slight differences are observed in the features
of the chelate ligands. The best least-squares plane for Ir, P2, C22,
˚
C21, C20 is almost planar (max. deviation of 0.081(6) A for C20),
while that for the Ir, P1, C3, C2, C1 atoms deviates significantly
˚
from planarity (max. deviation of 0.226(6) A for C1). The presence
The X-ray structures of 2, 4 (dichloromethane adduct), 7,
[8]ClO4 (chloroform adduct), and 9 have been determined†.
Selected bond distances and angles are listed in Table 1. Fig. 1–5
show molecular drawings for 4, 2, the cation in [8]ClO4, 7 and
9 together with the atomic labelling scheme used. Complexes
2, 4, and [8]ClO4 contain a common structural unit consisting
of a pseudo-octahedral iridium(III) moiety with four positions
occupied by the phosphorus and carbon atoms of two bidentate
ligands, and the other two positions occupied by one hydride
ligand and the phosphorus atom of PPh3 in 4, or the oxygen atom
of a bridging acyl group in 2 and [8]ClO4. The hydride is trans to the
phosphorus atom (P1 or P4) of the chelate bridging acylphosphine
in 2 and in [8]ClO4. The corresponding carbon atom (C1 or C58) is
trans to the other phosphorus atom (P2 or P3). The carbon atom
of the solvent molecule, dichloromethane, near this ring and
˚
bonded by weak hydrogen bonds to O1 ((O1 · · · C52) = 2.97(1) A;
O1–H–C = 98.7(5)◦) can explain this distortion. We have found a
similar distortion due to the solvent in other compounds.25
Complex 2 consists of dimers with two bridging acyl groups
in a head-to-tail arrangement and contains the same structural
motif as 4 but with the oxygen atoms of the bridging acyl groups
in 2 occupying the position of P3 in 4. Due to the low quality of
the diffraction data (see the Experimental section), the hydrogen
atoms bonded to the Ir atoms could not be located in a difference
Fourier synthesis and were not included in the model, however
there is no doubt of their location. The six-membered ring Ir1, C1,
O1, Ir2, C58, O4 adopts a boat conformation with an Ir1 · · · Ir2
˚
distance of 3.703(2) A, ruling out any interaction between the
◦
˚
Table 1 Selected bond lengths (A) and angles ( ) for 2, 4, 7, [8]ClO4and 9
2
[8]ClO4
Ir1–P1
Ir1–P2
Ir1–O4
Ir1–C1
Ir1–C20
2.324(7)
2.329(7)
2.26(2)
2.00(3)
1.96(3)
Ir2–P4
Ir2–P3
Ir2–O1
Ir2–C58
Ir2–C39
2.326(8)
2.314(8)
2.27(2)
2.00(3)
2.01(3)
Ir1–P1
Ir1–P2
Ir1–O4
Ir1–C1
Ir1–C20
Ir1–H1
C1–O1
C20–O2
2.296(2)
2.358(2)
2.181(5)
2.022(8)
2.007(8)
1.766
1.266(9)
1.243(9)
2.9629(4)
91.3(3)
80.6(2)
172.4(2)
89.6(3)
91.3
86.8(2)
104.8(1)
89.0(2)
169.8
83.7(3)
95.8(2)
83.8
Ir2–P4
Ir2–P3
2.301(2)
2.395(2)
2.268(5)
2.027(8)
2.025(7)
1.710
Ir2–O1
Ir2–C58
Ir2–C39
Ir2–H1
C58–O4
C39–O3
C1–O1
C20–O2
Ir1–Ir2
C20–Ir1–C1
C1–Ir1–P1
C1–Ir1–P2
C1–Ir1–O4
1.20(3)
1.29(4)
3.703(2)
92(1)
82.2(8)
170.7(8)
84.9(9)
C58–O4
C39–O3
1.25(3)
1.31(4)
1.244(9)
1.222(9)
Ir1–Ir2
C39–Ir2–C58
C58–Ir2–P4
C58–Ir2–P3
C58–Ir2–O1
95(1)
C20–Ir1–C1
C1–Ir1–P1
C1–Ir1–P2
C1–Ir1–O4
C1–Ir1–H1
C20–Ir1–P1
P1–Ir1–P2
P1–Ir1–O4
P1–Ir1–H1
C20–Ir1–P2
P2–Ir1–O4
P2–Ir1–H1
C20–Ir1–O4
C20–Ir1–H1
O4–Ir1–H1
O1–C1–Ir1
C58–O4–Ir1
Ir1–H1–Ir2
C39–Ir2–C58
C58–Ir2–P4
C58–Ir2–P3
C58–Ir2–O1
C58–Ir2–H1
C39–Ir2–P4
P4–Ir2–P3
P4–Ir2–O1
P4–Ir2–H1
C39–Ir2–P3
P3–Ir2–O1
P3–Ir2–H1
C39–Ir2–O1
C39–Ir2–H1
O1–Ir2–H1
O4–C58–Ir2
C1–O1–Ir2
85.6(3)
81.8(2)
169.0(2)
88.9(3)
86.3
90.8(2)
99.2(1)
96.5(1)
167.1
83.5(2)
101.8(1)
91.6
170.2(3)
83.3
81.6(8)
173.2(9)
84.2(8)
C20–Ir1–P1
P1–Ir1–P2
P1–Ir1–O4
95.0(9)
106.5(3)
89.5(5)
C39–Ir2–P4
P4–Ir2–P3
P4–Ir2–O1
94(1)
105.0(3)
91.0(5)
C20–Ir1–P2
P2–Ir1–O4
85(1)
98.1(5)
C39–Ir2–P3
P3–Ir2–O1
84(1)
97.0(5)
C20–Ir1–O4
174(1)
C39–Ir2–O1
174(1)
175.5(2)
99.6
84.8
120.1(5)
107.1(5)
116.9
88.3
121.1(6)
106.2(5)
O1–C1–Ir1
C58–O4–Ir1
129(2)
119(2)
O4–C58–Ir2
C1–O1–Ir2
130(2)
121(2)
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Table 1 (Contd.)
4
7
9
Ir–P1
Ir–P2
Ir–P3
Ir–C1
Ir–C20
Ir–H1
C1–O1
C20–O2
2.350(2)
2.360(2)
2.385(2)
2.074(6)
2.065(6)
1.906
Ir–P1
Ir–P2
Ir–H2
Ir–C1
Ir–C20
Ir–H1
C1–O1
C20–O2
O1–H3
2.317(2)
2.314(1)
1.679
1.991(6)
2.003(6)
1.680
1.284(7)
1.272(6)
1.34(8)
1.09(8)
2.420(7)
89.7(3)
83.6(2)
173.9(3)
101.1
Ir–P1
Ir–P2
Ir–Cl
Ir–C1
Ir–C20
Ir–H1
C1–O1
C20–O2
Ir–Rh
2.339(2)
2.348(2)
2.495(2)
2.017(6)
2.046(6)
1.678
1.262(6)
1.258(7)
3.7275(6)
Rh–O1
Rh–O2
2.104(4)
2.077(4)
2.072(6)
2.092(7)
2.099(7)
2.070(7)
1.407(9)
1.391(9)
Rh–C39
Rh–C40
Rh–C43
Rh–C44
C39–C40
C43–C44
1.216(7)
1.214(7)
O2–H3
O1–O3
C20–Ir–C1
C1–Ir–P1
C1–Ir–P2
C1–Ir–P3
C1–Ir–H1
C20–Ir–P1
P1–Ir–P2
P1–Ir–P3
P1–Ir–H1
C20–Ir–P2
P2–Ir–P3
P2–Ir–H1
C20–Ir–P3
C20–Ir–H1
P3–Ir–H1
82.3(2)
83.2(2)
165.7(2)
89.0(2)
96.3
92.0(2)
102.1(1)
104.6(1)
164.2
84.2(2)
102.3(1)
74.9
160.2(2)
72.3
C20–Ir–C1
C1–Ir–P1
C1–Ir–P2
C1–Ir–H2
C1–Ir–H1
C20–Ir–P1
P1–Ir–P2
P1–Ir–H2
P1–Ir–H1
C20–Ir–P2
P2–Ir–H2
P2–Ir–H1
H1–Ir–H2
C20–Ir–H1
C20–Ir–H2
O1–H3–O3
C20–Ir–C1
C1–Ir–P1
C1–Ir–P2
C1–Ir–Cl
C1–Ir–H1
C20–Ir–P1
P1–Ir–P2
P1–Ir–Cl
P1–Ir–H1
C20–Ir–P2
P2–Ir–Cl
P2–Ir–H1
C20–Ir–Cl
C20–Ir–H1
Cl–Ir–H1
O1–C1–Ir
O2–C20–Ir
93.6(2)
82.6(2)
175.1(2)
85.4(2)
101.8
166.6(2)
101.2(1)
105.8(1)
92.1
82.1(2)
96.6(1)
75.0
86.6(2)
76.0
C39–Rh–C40
C43–Rh–C44
O1–Rh–O2
39.5(2)
39.0(2)
90.0(2)
172.2(2)
148.0(2)
89.7(2)
95.8(2)
88.6(3)
86.9(2)
157.3(2)
163.2(2)
124.3(4)
123.8(4)
O1–Rh–C39
O1–Rh—C40
O1–Rh–C43
O1–Rh—C44
O2–Rh–C39
O2–Rh–C40
O2–Rh–C43
O2–Rh–C44
C1–O1–Rh
85.4
173.3(2)
102.5(5)
97.8
82.6
84.2(2)
78.8
94.8
173.5
96.0
84.3
C20–O2–Rh
91.1
161.5
129.3(4)
128.1(5)
168(8)
Table 2 Crystal data and refinement data for 2, [8]ClO4, 4, 7 and 9
Crystal data
2
[8]ClO4
4
7
9
Empirical formula
Formula weight
Temperature/K
C76H58O4P4Ir2
1543.5
296(2)
[C76H57O4P4Ir2]ClO4·CHCl3
1761.31
296(2)
[C56H44O2P3Ir]·CH2Cl2
[C38H31O2P2Ir]
773.77
296(2)
[C46H41Cl1O2P2IrRh]
1018.29
296(2)
1118.95
296(2)
Crystal system, space group
Triclinic, P-1
11.462(3)
13.688(3)
23.598(5)
79.179(4)
88.238(4)
67.565(4)
3357(1)
Triclinic, P-1
12.338(1)
15.669(1)
18.640(1)
92.200(1)
103.952(1)
96.612(1)
3465.8(4)
2
1.688
4.140
1732
1.31 to 25.00
Triclinic, P-1
11.143(1)
12.964(1)
17.830(2)
84.247(2)
74.945(2)
76.930(2)
2420.5(4)
2
1.535
3.010
1120
1.18 to 25.00
Triclinic, P-1
11.4493(7)
11.4628(7)
13.7750(8)
72.076(1)
67.555(1)
79.943(1)
1586.4(2)
2
1.620
4.342
764
1.66 to 24.99
Triclinic, P-1
12.264(1)
13.030 (1)
14.316(1)
87.480(2)
78.631(2)
63.784(2)
2009.7(3)
2
1.683
3.902
1004
1.45 to 26.37
˚
a/A
˚
b/A
˚
c/A
a/◦
b/◦
c /◦
3
˚
V/A
Z
2
Dc/g cm−3
1.527
4.103
1520
0.88 to 26.00
−14, −16, −29
to 14, 16, 27
27 987
12 755
0.2025
l(Mo Ka)/mm−1
F(000)
h range/◦
Index ranges
−14, −16, −16 to 14, 18, 22 −10, −15, −21 to 13,
−13, −13, −16 to −15, −14,−17 to 13,
15, 14
18 421
8228
0.0342
96.6%
8228/0/571
1.047
13, 13, 16
12 249
15, 17
17 331
7929
0.0646
96.3%
7929/0/478
0.88
0.040(5545)
Reflections collected
Independent reflections
Rint
26 717
11 888
0.0943
97.2%
11 888/0/836
0.980
0.0457 (8363)
5563
0.0782
99.5%
5563/0/397
0.96
Completeness to theta
Data/restraints/parameters
GOF on F2
96.7%
12 755/0/271
0.983
R1 (reflections observed)
0.1034 (4375)
0.0403 (7082)
0.036 (4591)
[I>2r(I)] a
wR2 (all data)b
0.3540
0.1181
0.1169
0.074
0.074
a R1 = RꢁFo| − |Fcꢁ/R|Fo| b wR2 = {R[w(Fo − Fc2)2]/R[w(Fo2)2]}.
2
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Fig. 3 ORTEP view of the cation in compound [8]ClO4 showing the
atomic numbering (25% probability ellipsoids). The hydrogen atoms,
except for one, have been omitted for clarity.
Fig. 1 ORTEP view of complex 4 showing the atomic numbering (25%
probability ellipsoids). The hydrogen atoms, except for one, have been
omitted for clarity.
Fig. 2 ORTEP view of complex 2 showing the atomic numbering (25%
probability ellipsoids). The hydrogen atoms have been omitted for clarity.
metal centres. In the binuclear species [8]ClO4 the two metal
centres are triply bridged by two acyl groups in a head-to-tail
arrangement as in 2, and by a hydride that was located in a
final Fourier difference syntheses, in a symmetrical fashion. The
presence of a bridging hydride in [8]ClO4, instead of two terminal
hydrides in 2, has an influence on the dihedral angle between
the planes Ir1, C1, O4 and Ir2, C58, O1 being 76.1(8)◦ for 2
and 69.4(2)◦ for [8]ClO4, and also on the Ir1–Ir2 distance of
Fig. 4 ORTEP view of complex 7 showing the atomic numbering and the
intramolecular hydrogen bond (30% probability ellipsoids). The hydrogen
atoms, except for three, have been omitted for clarity.
1
by the 13C{ H} NMR data.14 The Ir–O distances are within the
expected range.8,14,28
In complex 7 the two hydride ligands are mutually trans, the
phosphorus atoms and the carbon atoms of the acyl groups are
almost co-planar with the iridium atom, and the two bidentate
ligands are bonded between them by hydrogen bonds, as in other
˚
2.9629(5) A for [8]ClO4, which compares well with those found
in other Ir(l-H)Ir complexes.26 The IrHIr moiety in [8]ClO4 can
therefore be interpreted as forming a two-electron three-centre
bond with a significant Ir–Ir bonding interaction. Bridging acyls
can be described by acyl ↔ oxy-carbene resonance structures, and
this is reflected by shorter M–C and longer C–O bond distances
than in terminal acyl ligands.5,6,11,13,14,27 In complex [8]ClO4 the Ir–
C(bridging) and the Ir–C(terminal) distances are equal and the
C–O distances, bridging or terminal, are also equal confirming
the low carbenoid character of the acyl bridging groups, suggested
irida-b-diketones.4,7 The Ir–C bond lengths, 1.997(6) A, are shorter
˚
˚
than those in complex 4 and the C–O distances, 1.277(5) A, are
˚
longer than those in 4. The O1–O2 distance, 2.420(7) A, is in
accordance with a strong hydrogen-bridge bond in mononuclear
complexes,4,7,27,29 and the O1–H3–O3 angle (168(8)◦) is consistent
with a nearly linear O–H–O hydrogen bond. The irida-cycle
comprising the acyl(hydroxycarbene) group is essentially planar.
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methanol to undergo dehydrodechlorination and afford a din-
uclear dihydridodi-l-acyl-diiridium(III) species [Ir2H2(PPh2(o-
C6H4CO))2(l-PPh2(o-C6H4CO))2] (2). Complex 2 reacts further
and the reaction products depend on the base used. Strong
bases lead to hydrogenation and protonation to afford a novel
dihydridoacylhydroxycarbene [IrH2{(PPh2(o-C6H4CO))2H}] (7)
with carbenoid character. The amine promotes partial de-
hydrogenation to afford
a cationic di-l-acyl-l-hydridodii-
ridium(III) derivative [Ir2(l-H){l-PPh2(o-C6H4CO)}2(PPh2(o-
C6H4CO))2]+ (8). [Rh(cod)(OMe)]2 promotes the deprotona-
tion of hydridoirida-b-diketone complexes to afford the kinet-
ically favoured hydridoirida-b-diketonaterhodium(I) complexes,
which isomerise to the thermodynamically favoured l-acyl-l-
hydridodiiridium(III) rhodium(I) species.
Experimental
General
Fig. 5 ORTEP view of complex 9 showing the atomic numbering (25%
probability ellipsoids). The hydrogen atoms, except for one, have been
omitted for clarity.
The preparation of the metal complexes was carried out at
room temperature under nitrogen by standard Schlenk tech-
niques. [IrH{(PPh2(o-C6H4CO))2H}Cl] (1a) [IrH{(PPh2(o-C6H4-
CO))2H}(py)]ClO4 (1b), [IrH{(PPh2(o-C6H4CO))2H}(CO)]ClO4
(1c) and [Rh(cod)(OMe)]2 were prepared as previously
reported.4,7,31 Microanalysis was carried out using a Leco CHNS-
932 microanalyser. Conductivities were measured in acetone
solution using a Metrohm 712 conductimeter. IR spectra were
recorded using a Nicolet FTIR 510 spectrophotometer in the
range 4000–400 cm−1 using KBr pellets. NMR spectra were
recorded using Bruker Avance DPX 300 or Bruker Avance 500
In contrast with 4, the best least-squares planes for Ir, P1, C3,
C2, C1 and Ir, P2, C22, C21, C20 atoms are practically planar
and are within experimental error. The maximum deviation of
the best least-squares plane for the Ir, C1, O1, O2, C20 atoms is
˚
0.015(6) A for C20. The dihedral angles between this plane and
the best least-squares planes of the Ir, P1, C3, C2, C1 and Ir, P2,
C22, C21, C20 atoms are 2.4(1) and 0.7(1)◦, respectively. These
features support to some extent the carbenoid character of the
carbon atoms bonded to iridium.30
1
spectrometers. 1H and 13C{ H} (TMS internal standard), 31P
1
and 31P{ H} (H3PO4 external standard) spectra were measured
In the bimetallic compound 9 the two metallic centres are
bonded by two acyl groups in a head-to-head arrangement. The
molecule can be described as a square-planar rhodium(I) fragment
and a pseudo-octahedral iridium(III) moiety bonded by two acyl
groups. The six-membered ring Ir, C1, O1, Rh, O2, C20 adopts
a boat conformation as in other rhena- or platina-b-diketonato
from CDCl3 or CD2Cl2 solutions. Mass spectra were recorded
using a VG Autospec by liquid secondary ion (LSI) MS using
nitrobenzylalcohol as the matrix and a caesium gun (Universidad
de Zaragoza).
Bis{l-[(2-diphenylphosphino-jP)benzoyl-jC:jO][(2-diphenyl-
phosphino-jP)benzoyl-jC]hydridoiridium(III)} (2). To a metha-
nol suspension of 1a (100 mg, 0.123 mmol) KOH (6.90 mg,
0.123 mmol) or NaHCO3 (20.7 mg, 0.246 mmol) was added and
stirred for 2 h (KOH) or 24 h (NaHCO3) yielding a brown solid
that was subsequently filtered off, washed with methanol and
vacuum dried. Yield: 70%. IR (cm−1): 2042(s), t(Ir–H); 1603(s),
transition metal complexes.1,5 The Ir · · · Rh distance of 3.7275(6) A
˚
rules out any interaction between the metal centres. The rhodium
atom has a normal square-planar geometry with Rh–O and Rh–C
distances within the expected ranges. The geometry of the iridium
atom is similar to that of 7, with a chloride atom instead of a
hydride. The Ir–C and the C–O distances in 9 are equivalent
and do not differ significantly from those in 7. In the dinuclear
complex 9 the best least-squares planes for the Ir, P1, C3, C2,
C1 and Ir, P2, C22, C21, C20 atoms deviate significantly from
=
=
t(C O)t; 1504(s), t(C O)b. FAB MS: calcd for C76H58Ir2O4P4:
1544; observed: 1543 [M–H]+. Anal. calcd for C76H58Ir2O4P4: C
59.14; H 3.79. Found: C 58.92; H 3.96. 1H NMR (CDCl3): d −5.08
(ddd, 1H, 2J(P, H)trans = 125.2 Hz, 2J(P, H)cis = 21.9 Hz,5J(P, H) =
˚
˚
planarity (max. deviation of 0.305(6) A for C1 and 0.270(6) A for
C20). The best least-squares plane Ir, C1, O1, O2, C20 present the
5.0 Hz IrH). 31P NMR (CDCl3): d 24.8 (s, Pa), 22.8 (d, J(H,
2
˚
P)trans = 125 Hz, Pb). 13C{ H} NMR (CDCl3): d 274.3 (d, J(P,
1
2
maximum deviation for C1, 0.292(6) A and the dihedral angles
between this plane and the best least-squares planes of the Ir,
P1, C3, C2, C1 and Ir, P2, C22, C21, C20 atoms are 18.4(1) and
14.3(1)◦, respectively. A search of the Cambridge crystallographic
database failed to locate a structurally characterised example of a
Rh–Ir-l-acyl complex.
C)trans = 103 Hz, COb), 203.8 (s, COt).
(OC-6–43)-Bis[(2-diphenylphosphino-jP)benzoyl-jC]hydrido-
pyridineiridium(III) (3), (OC-6–43)-bis[(2-diphenylphosphino-jP)-
benzoyl-jC]hydridotriphenylphosphineiridium(III) (4), (OC-6–34)-
dimethylsulfoxidebis[(2-diphenylphosphino-jP)benzoyl-jC]hydri-
doiridium(III) (5) and (OC-6–42)-carbonylbis[(2-diphenylphosph-
ino-jP)benzoyl-jC]hydridoiridium(III) (6). To a dichloromethane
solution of 2 (50 mg, 0.032 mmol) an excess (0.128 mmol) of the
corresponding ligand was added or was connected to a balloon
Conclusions
The hydridoirida-b-diketone [IrHCl{(PPh2(o-C6H4CO))2H}] (1a)
reacts with bases such as NEt3, NaHCO3 or KOH in
4608 | Dalton Trans., 2008, 4602–4611
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filled with CO. After 18 h of stirring, the addition of diethyl ether
gave yellow precipitates that were subsequently filtered, washed
with diethyl ether and vacuum dried. Data for 3: yield: 45%.
3.59. 1H NMR (CDCl3): d −11.58 (tt, 1H, 2J(P, H)trans = 55.7 Hz,
2
2J(P, H)cis = 12.7 Hz, IrH). 31P NMR (CDCl3): d 29.8 (d, J(H,
1
P)trans = 59 Hz, Pb), 11.4 (s, Pa). 13C{ H} NMR (CDCl3): d 239.9
−1
IR (cm ): 2026(m), t(Ir–H); 1596(s), t(C O). Anal. calcd for
(d, 2J(P, C)trans = 95 Hz, COb), 200.0 (s, COt).
=
C43H34NIrO2P2·CH2Cl2: C 56.47; H 3.88; N 1.50. Found: C 56.19;
Reaction of [8]ClO4 with HCl. HCl gas was bubbled at room
temperature through a methanol suspension of [8]ClO4 (10 mg,
0.006 mmol) for 30 min, upon which dissolution of the solid
occurred. The solvent was evaporated and the residue analysed by
NMR. According to the spectra the solid contains only compound
[8]Cl.
H 4.11; N 1.70. 1H NMR (CDCl3): d −7.32 (dd, 1H, 2J(P, H)trans
=
131.6 Hz, J(P, H)cis = 19.5 Hz, IrH). 31P{ H} NMR (CDCl3): d
2
1
33.1 (d, 2J(P, P) = 3 Hz, Pb), 24.1 (d, Pa). 13C{ H} NMR (CDCl3):
1
d 237.0 (d, 2J(P, C)trans = 104 Hz, CO), 213.2 (s, CO). Data for 4:
−1
=
yield: 54%. IR (cm ): 2101(m), t(Ir–H); 1619(s), t(C O). FAB
MS: calcd for C56H43O2P3Ir: 1034; observed: 1033 [M–H]+. Anal.
calcd for C56H43O2P3Ir·0.5CH2Cl2: C 63.04; H 4.21. Found: C
Chlorido-1j-(g2,g2-cycloocta-1,5-diene)-2j-di-l-[(2-diphenylph-
osphino-1jP)benzoyl-1jC:2jO]-hydrido-1j-iridium(III)rhodium(I)
(9). To a dichloromethane solution of 1 (50 mg, 0.062 mmol)
was added [Rh(cod)(OMe)]2 (15 mg, 0.031 mmol) and stirred for
62.54; H 4.46. 1H NMR (CDCl3): d −8.94 (ddd, 1H, 2J(P, H)trans
=
1
116.8 Hz, J(P, H)cis = 21.0; 19.5 Hz, IrH). 31P{ H} NMR (CDCl3):
d 23.6 (dd, Pb), 17.8 (dd, Pa), −5.1 (dd, Pc = PPh3), Jab = 6 Hz,
1
Jac = 9 Hz, Jbc = 16 Hz. 13C{ H} NMR (CDCl3): d 225.8 (dd,
30 min. Evaporation of the solvent gave an orange solid. Yield:
2
2
−1
2J(P, C)trans = 86 Hz, J(P, C)cis = 7 Hz, CO), 225.5 (dd, J(P,
60%. IR (cm ): 2142(m), t(Ir–H); 1519(s), t(C O)b. FAB MS:
=
2
C)trans = 93 Hz, J(P, C)cis = 9 Hz, CO). Data for 5: yield: 77%.
calcd for C46H41ClIrO2P2Rh: 1018; observed: 1018 [M]+. Anal.
calcd for C46H41ClIrO2P2Rh: C 54.25; H 4.06. Found: C 54.19;
H 4.11. 1H NMR (CDCl3): d −19.90 (t, 1H, 2J(P, H) = 16.3 Hz,
−1
=
=
IR (cm ): 2036(m), t(Ir–H); 1609(s), t(C O); 1097(s), t(S O).
Anal. calcd for C40H35IrO3P2S·CH2Cl2: C 52.68; H 3.99; S 3.43.
Found: C 52.67; H 3.89; S 3.58. 1H NMR (CDCl3): d −8.72 (dd,
=
IrH), 4.19 (s, 4H, CH), 2.62 (m, 4H, CH2), 1.76 (m, 4H, CH2).
2
2
1
1
1H, J(P, H)trans = 117.9 Hz, J(P, H)cis = 18.3 Hz, IrH), 1.89 (s,
31P{ H} NMR (CDCl3): d 20.4 (s). 13C{ H} NMR (CDCl3): d
3H, CH3), 3.43 (s, 3H, CH3). 31P{ H} NMR (CDCl3): d 23.7 (d,
258.4 (d, 2J(P, C)trans = 102 Hz, COb), 75.4 (d, 1J(Rh, C) = 15 Hz,
1
2J(P, P) = 7 Hz, Pb), 22.7 (d, Pa). 13C{ H} NMR (CDCl3): d 234.1
CH), 30.8 (s, CH2).
1
=
2
2
(d, J(P, C)trans = 93 Hz, CO), 217.7 (d, J(P, C)cis = 7 Hz, CO),
(g2,g2 -Cycloocta-1,5-diene)-2j-di-l-[(2-diphenylphosphino-
55.6 (s, CH3), 45.1 (s, CH3).
1jP)benzoyl-1jC:2jO]-hydrido-1j-pyridine-1j-iridium(III)rho-
dium(I) perchlorate (10) and carbonyl-1j-(g2,g2-cycloocta-1,5-
diene)-2j- di-l-[(2-diphenylphosphino-1jP)benzoyl-1jC:2jO]-hy-
drido-1j-iridium(III)rhodium(I) perchlorate (11). To a dichlo-
romethane solution of 1b or 1c (51.38 or 48.62 mg, 0.054 mmol)
[Rh(cod)(OMe)]2 was added (12.80 mg, 0.027 mmol). Refluxing
for 90 min (10) or stirring for 30 min (11) followed by evaporation
(OC-6–22)-[(2-Diphenylphosphino-jP)benzoyl-jC][(2-diphenyl-
phosphino-jP)benzoylium-jC]dihydridoiridium(III) (7). To
a
methanol suspension of 1a (50 mg, 0.062 mmol) KOH (3.5 mg,
0.062 mmol) or NaHCO3 (10.4 mg, 0.1◦24 mmol) was added. The
obtained suspension was heated to 65 C for 3 h. After cooling,
the yellow solid was decanted, washed with methanol and vacuum
−1
=
dried. Yield: 67%. IR (cm ): 1773(s), t(Ir–H); 1586(m), t(C O).
of the solvent gave yellow solids. Data for 10: yield: 57%. IR
−1
(cm ): 2152(w), t(Ir–H); 1517(s), t(C O)b. KM (X−1 cm2 mol−1):
=
Anal. calcd for C38H31IrO2P2: C 58.98; H 4.04. Found: C 58.58; H
4.30. 1H NMR (CDCl3): d −8.76 (t, 2H, 2J(P, H) = 18.1 Hz, IrH),
126. Anal. calcd for C51H46ClNIrO6P2Rh·0.25CH2Cl2: C 52.05;
1
1
22.66 (s, 1H, OHO). 31P{ H} NMR (CDCl3): d 31.9 (s). 13C{ H}
H 3.96; N 1.18. Found: C 51.96; H 3.76; N 1.25. 1H NMR
NMR (CDCl3): d 259.3 (d, 2J(P, C)trans = 99 Hz, CO).
(CDCl3): d −19.98 (t, 1H, 2J(P, H) = 18.0 Hz, IrH), 4.01 (s,
4H, CH), 2.21 (s, 4H, CH2), 1.73 (s, 4H, CH2). 31P{ H} NMR
1
=
l-Hydridobis{l-[(2-diphenylphosphino-jP)benzoyl-jC:jO]–[(2-
diphenylphosphino-jP)benzoyl-jC]iridium(III)} chloride, [8]Cl
and l-hydridobis{l-[(2-diphenylphosphino-jP)benzoyl-jC:jO]–
(CDCl3): d 24.2 (s). 13C{ H} NMR (CD2Cl2): d 258.3 (d, J(P,
1
2
=
C)trans = 96 Hz, COb), 75.4 (s, br CH), 30.2 (s, CH2). Data
−1
≡
for 11: yield: 75%. IR (cm ): 2096(s), t(Ir–H); 2006(s), t(C O);
[(2-diphenylphosphino-jP)benzoyl-jC]iridium(III)}
perchlorate,
1529(s), t(C O)b. KM (X−1 cm2 mol−1): 122. FAB MS: calcd
=
[8]ClO4. To a methanol suspension of 1a (50 mg, 0.062 mmol)
Et3N (7.0 mg, 0.0◦7 mmol) was added. The obtained suspension
was heated to 65 C for 3 h to obtain a solution. After cooling,
the solvent was evaporated to dryness and the solid residue
was dissolved in dichloromethane. The solution was washed
three times with distilled water and dried over magnesium sulfate.
Filtration and evaporation of the solvent gave a yellow solid,
[8]Cl, which was collected. Yield: 47%. To a dichloromethane
solution of [8]Cl (50 mg, 0.032 mmol) was added AgClO4
(13.1 mg, 0.064 mmol). After being stirred for 30 min the silver
salts were filtered and the dichloromethane was evaporated to
for C47H41IrO3P2Rh: 1011; observed: 1011 [M]+. Anal. calcd for
C47H41ClIrO7P2Rh·0.5CH2Cl2: C 49.49; H 3.67. Found: C 49.47; H
3.86. 1H NMR (CD2Cl2): d −9.02 (t, 1H, 2J(P, H) = 18.0 Hz, IrH),
1
4.38 (s, 4H, CH), 2.62 (s, 4H, CH2), 1.93 (m, 4H, CH2). 31P{ H}
=
NMR (CDCl3): d 14.8(s). 13C{ H} NMR (CD2Cl2): d 244.9 (d,
1
2J(P, C)trans = 83 Hz, COb), 172.7 (s, C O), 80.5 (d, J(Rh, C) =
1
≡
=
15 Hz, CH), 30.6 (s, CH2).
Chlorido-1j-(g2,g2-cycloocta-1,5-diene)-2j-l-[(2-diphenylphos-
phino-1jP)benzoyl-1jC:2jO]-[(2-diphenylphosphino-1jP)benzoyl-
1jC]-l-hydrido-iridium(III)rhodium(I) (12).
A methanol sus-
give a yellow solid, [8]ClO4, which was collected. Yield: 73%. IR
pension of 9 (63.14 mg, 0.062 mmol) was heated to 65 ◦C for 3 h
−1
(cm ): 1624(m), t(C O)t; 1522(s) t(C O)b. KM (X−1 cm2 mol−1):
67 ([8]Cl); 132 ([8]ClO4). FAB MS: calcd for C76H57Ir2O4P4: 1543;
observed: 1543 [M]+. Anal. calcd for C76H57ClIr2O4P4·CH2Cl2
([8]Cl): C 55.61; H 3.58. Found: C 55.46; H 3.79. Anal. calcd for
C76H57ClIr2O8P4 ([8]ClO4): C 55.59; H 3.50. Found: C 55.41; H
to obtain a solution. Evaporation of the solvent gave an orange
=
=
−1
=
=
solid. Yield: 64%. IR (cm ): 1616(s), t(C O)t; 1507(s), t(C O)b.
FAB MS: calcd for C46H41ClIrO2P2Rh: 1018; observed: 1018
[M]+. Anal. calcd for C46H41ClIrO2P2Rh: C 54.25; H 4.06. Found:
C 54.07; H 3.84. 1H NMR (CDCl3): d −13.79 (dt, 1H, 2J(P,
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2
1
H)trans = 89.0 Hz, J(P, H)cis = J(Rh, H) = 18.0 Hz, IrH), 4.17
whereas the rest of atoms were refined anisotropically. The
hydrogen atoms were included in their calculated positions and
refined riding on the respective carbon atoms. The hydrogen atoms
bonded to the Ir atoms could not be located in a difference Fourier
synthesis and were not included in the model. Nevertheless, the
atom parameters gave reasonable deviations in distances and
angles. The final refinement converged to R1 = 0.1034 (4375
reflections observed) and wR2 = 0.3540 (all reflections) and showed
high values of residual non-modelled electronic density due to the
bad quality of the crystal.
=
=
(s, 2H, CH), 3.80 (s, 2H, CH), 2.17 (m, 4H, CH2), 1.60 (m,
4H, CH2). 31P NMR (CDCl3): d 27.4 (d, 2J(H, P)trans = 89 Hz, Pb),
1
7.8 (s, br, Pa). 13C{ H} NMR (CD2Cl2): d 240.7 (d, 2J(P, C)trans
=
2
1
104 Hz, COb), 204.0 (d, J(P, C) = 5 Hz, COt), 79.6 (d, J(Rh,
1
=
=
C) = 13 Hz, CH), 78.6 (d, J(Rh, C) = 13 Hz, CH), 30.7 (s,
CH2), 30.4 (s, CH2).
(g2 ,g2 -Cycloocta-1,5-diene)-2j-l-[(2-diphenylphosphino-1jP)-
benzoyl-1jC:2jO]-[(2-diphenylphosphino-1jP)benzoyl-1jC]-l-hy-
drido-pyridine-1j-iridium(III)rhodium(I) perchlorate (13). A met-
hanol solution of 10 (56.29 mg, 0.053 mmol) was heated to 65 ◦C
for 2 h. The addition of diethyl ether gave an orange precipitate
For 4, 7, [8]ClO4 and 9 anisotropic parameters were used in
−
the last cycles of the refinement with the exception of the ClO4
oxygen atoms ([8]ClO4) and the solvent molecule dichloromethane
(4), which were refined isotropically. The hydrogen atoms were
included at their calculated positions and refined riding on their
respective carbon atoms, except the H atoms bonded to Ir and O
atoms, which were located in a final Fourier difference synthesis.
The metal hydrides were included with fixed isotropic factors and
coordinates in 4 and [8]ClO4 while for 7 and 9 they were refined
riding on their respective Ir atom with geometrical constraints. For
9 the enolic hydrogen was refined with fixed thermal parameters.
The final R and Rw values are shown in Table 2. The largest residual
peaks in the final difference map are near to the Ir atoms for
[8]ClO4, 7 and 9, whereas for 4 they are in the vicinity to the
solvent molecule of dichloromethane.
that was filtered off, washed with diethyl ether and vacuum dried.
−1
=
=
Yield: 57%. IR (cm ): 1600(s), t(C O)t; 1519(s), t(C O)b. KM
(X−1 cm2 mol−1): 128. Anal. calcd for C51H46ClNIrO6P2Rh: C
52.74; H 3.99; N 1.21. Found: C 52.55; H 3.83; N 1.19. 1H NMR
2
2
(CDCl3): d −13.87 (dt, 1H, J(P, H)trans = 81.0 Hz, J(P, H)cis
=
1
=
J(Rh, H) = 16.0 Hz, IrH), 4.37 (s, 4H, CH), 2.18 (m, 4H, CH2),
1.80 (m, 4H, CH2). 31P{ H} NMR (CDCl3): d 34.2 ( d, 2J(P, P) =
1
7 Hz, Pb), 13.8 (d, Pa).
(g2,g2-Cycloocta-1,5-diene)-2j-bis[(2-diphenylphosphino-1jP)-
benzoyl-1jC]-di-l-hydrido-iridium(III)rhodium(I) (14). To a di-
chloromethane solution of 7 (50 mg, 0.065 mmol) was added
[Rh(cod)(OMe)]2 (15.6 mg, 0.032 mmol) and stirred for 5 min,
evaporation of the solvent gave an orange solid. Yield: 89%.
−1
=
IR (cm ): 2033(m), t(Ir–H); 1597(s), t(C O)t. Anal. calcd for
Acknowledgements
C46H42IrO2P2Rh·0.5CH2Cl2: C 54.42; H 4.22. Found: C 54.50; H
1
2
Partial financial supports by UPV and Diputacio´n Foral de
Guipuzcoa are gratefully acknowledged.
4.41. H NMR (CDCl3): d −12.24 (dt, 1H, J(P, H) = 14.0 Hz,
1
=
J(Rh, H) = 12.0 Hz, IrH), 4.11 (s, 4H, CH), 2.10 (m, 4H, CH2),
1.60 (m, 4H, CH2). 31P{ H} NMR (CDCl3): d 28.2 (s). 13C{ H}
1
1
1
=
NMR (CD2Cl2): d 77.6 (d, J(Rh, C) = 13 Hz, CH), 31.0 (s,
References
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©