Synthesis of a library of iridium-containing dinuclear complexes with bridging PNNN and PNNP ligands (BL), [LM(μ-BL)M′L′]BF 4. 2. Preparation, basic coordination properties, and reactivity of the carbonyl complexes

Article abstract of DOI:10.1021/om050897e

A series of dinuclear carbonyl complexes with PNNP and PNNN ligands, [(L)M(PNNX)M′(L)]BF₄ (X = P, N; M(L), M′(L′) = Ir(CO)₂, Rh(CO)₂, Pd(allyl)), have been prepared by carbonylation (1 atm) of the corresponding cod complexes, and the Rh/Ir complexes have been further converted to μ-η¹: η²-acetylide complexes, where effective π-back-donation to the acetylide ligand is essential to stabilize them. On the basis of the stability of the acetylide complexes, the π-donating ability of the metal fragment in the PNNX system is estimated to be (P,N)Rh > (P,N)Ir > (N,N)M. The dinuclear PNNX complexes catalyze alkyne hydrogenation, alkene hydroformylation, and allylation of aniline with allyl alcohol, and, for the allylation, a dinuclear mechanism involving activation of allyl alcohol by interaction with a CO ligand is proposed.

Full text of DOI:10.1021/om050897e

Organometallics 2006, 25, 1359-1367
1359
Synthesis of a Library of Iridium-Containing Dinuclear Complexes
with Bridging PNNN and PNNP Ligands (BL), [LM(µ-BL)M′L′]BF4.
2. Preparation, Basic Coordination Properties, and Reactivity of the
Carbonyl Complexes
Christian Dubs, Toshiki Yamamoto, Akiko Inagaki, and Munetaka Akita*
Chemical Resources Laboratory, Tokyo Institute of Technology, R1-27, 4259 Nagatsuta, Midori-ku,
Yokohama 226-8503, Japan
ReceiVed October 18, 2005
A series of dinuclear carbonyl complexes with PNNP and PNNN ligands, [(L)M(PNNX)M′(L)]BF4
(X ) P, N; M(L), M′(L′) ) Ir(CO)2, Rh(CO)2, Pd(allyl)), have been prepared by carbonylation (1 atm)
of the corresponding cod complexes, and the Rh/Ir complexes have been further converted to µ-η1:η2-
acetylide complexes, where effective π-back-donation to the acetylide ligand is essential to stabilize
them. On the basis of the stability of the acetylide complexes, the π-donating ability of the metal fragment
in the PNNX system is estimated to be (P,N)Rh > (P,N)Ir > (N,N)M. The dinuclear PNNX complexes
catalyze alkyne hydrogenation, alkene hydroformylation, and allylation of aniline with allyl alcohol, and,
for the allylation, a dinuclear mechanism involving activation of allyl alcohol by interaction with a CO
ligand is proposed.
complete conversion to the desired carbonyl complexes. Car-
bonylation of the heterodinuclear complexes 1′c, 2′b-d, and
4′ at ambient temperature, on the other hand, produces a
statistical mixture of homo- and heterometallic complexes
through a metal exchange process. For example, carbonylation
of 1′c affords a 1:2:1 mixture of 1a, 1c, and 1b, and that of 2c′
gives a 1:1:1:1 mixture of the four possible products, which is
also obtained from the isomeric counterpart 2′d. This metal
exchange process, however, can be suppressed by conducting
the carbonylation at 0 °C. The Ir(PNNN)Rh complex 2′c is
converted to 2c by the repeated carbonylation at 0 °C, and thus,
to get reproducible results, the repeated carbonylation at 0 °C
is preferable for every case.
The obtained carbonyl complexes are readily characterized
by the appearance of ν(CO) vibrations. The specific formation
of the distinctive isomeric species 2c,d from 2′c,d, respectively,
leads to the conclusion that the carbonylation proceeds with
retention of the metal-coordinated sites, when the reaction is
carried out under controlled conditions. Molecular structures
of the homonuclear Rh-PNNN complex 2a and the hetero-
nuclear Pd(PNNN)Ir complex 5 have been determined by X-ray
crystallography. Their ORTEP views and selected structural
parameters are shown in Figure 1 and Table 1, respectively,
and the structural features will be discussed later, together with
those of related compounds. It is also found that 2a forms
cocrystals with the P-oxidized species 7 (Chart 1), which results
from adventitious oxidation during a prolonged recrystallization
period. Because an isolated sample of 2a is converted into 7
upon stirring its solution in air, it is suggested that the P,N-
chelate in 2a is opened via P-Rh dissociation and the resultant
free P moiety is oxidized and recoordinated to the Ir center to
furnish 7.
Introduction
In the preceding paper a unique systematic synthetic method
for a series of homo- and heterodinuclear complexes with the
PNNN and PNNP ligands has been reported.1 For further
extension of the library, the obtained labile cod complexes (cod
) 1,5-cyclooctadiene) are converted into carbonyl and acetylide
complexes, and their basic coordination properties resulting from
a combination of (1) the central metals, (2) ligands, and (3)
coordination sites (P,N vs N,N) have been studied.
Results and Discussion
Carbonylation of η4-Cyclooctadiene Complexes. The cod
complexes 1′-5′ reported in the preceding paper are subjected
to carbonylation (1 atm) (Scheme 1). The homodinuclear
complex (2′a) and the Pd-containing complexes (3′ and 5′) are
readily converted to the desired carbonyl complexes in a manner
similar to the synthesis of 1a,b reported by Bosnich,2 but
incomplete conversion and/or metal exchange are observed for
the other cases, unless the carbonylation is carried out under
controlled conditions. The incomplete conversion, however, can
be overcome by isolation of a partly carbonylated reaction
mixture followed by repeated carbonylation. In this case, the
cod ligand is not completely liberated from the metal coordina-
tion sphere. For example, in carbonylation of a related P,N-
coordinated mononuclear species, [(κ2-py-CH2PPh2)Ir(cod)]BF4,
a η2-cod-coordinated product, [(µ-η2:η2-cod){Ir(κ2-py-CH2-
PPh2)(CO)2}2](BF4)2 (6),3 has been isolated and charac-
terized by X-ray crystallography. Removal of the liberated cod
molecule in the reaction mixture, therefore, is essential for
(1) Dubs, C.; Yamamoto, T.; Inagaki, A.; Akita, M. Organometallics
2006, 25, 1344.
Careful analysis of the carbonylation of the pair of Ir-Rh/
PNNN complexes 2′c,d reveals that the carbonylation proceeds
in a stepwise manner (Scheme 2). As described in the preceding
paper,1 the deshielded H6 signal (δH ∼8; doublet) of the pyridyl
group serves as a diagnostic for the coordination of the M(cod)
fragments (M ) Ir, Rh) to the N,N site.1 On going from 2′c to
(2) (a) Schenk, T. G.; Downs, J. M.; Milne, C. R. C.; Mackenzie, P. B.;
Boucher, H.; Whelan, J.; Bosnich, B. Inorg. Chem. 1985, 24, 2334. (b)
Schenk, T. G.; Milne, C. R. C.; Sawyer, J. F.; Bosnich, B. Inorg. Chem.
1985, 24, 2338. (c) Bosnich, B. Inorg. Chem. 1999, 38, 2554.
(3) Complex 6 is obtained as a minor byproduct of the carbonylation
and has been characterized only by X-ray crystallography. Crystallographic
data are included in the Supporting Information.
10.1021/om050897e CCC: $33.50 © 2006 American Chemical Society
Publication on Web 02/04/2006

1360 Organometallics, Vol. 25, No. 6, 2006
Dubs et al.
Scheme 1
Chart 1
f <8 ppm (9: overlapped with the other signals; (N,N)Rh-
(cod)) f 8.51 ppm (2d: (N,N)Rh(CO)2). In this case, therefore,
the (N,N)Rh(cod) part is carbonylated at the final stage. The
stepwise conversions can also be followed by IR, but no useful
information is obtained from the 31P NMR data, because no
significant shift of the 31P NMR signals is observed. It is notable
that the Ir(cod) parts are the preferential carbonylation sites
irrespective of the coordination environment (P,N vs N,N).
µ-η1:η2-Acetylide Complexes: σ- vs π-Coordination De-
pendent on the Metal and Ligand Donor Sets (P,N vs N,N).4,5
The P,N and N,N coordination sites in the heterodinuclear
complexes, in particular, in the unsymmetrical PNNN com-
plexes, show variable coordination properties dependent upon
the combination of the metals (Ir vs Rh) and the coordination
sites (P,N vs N,N). The µ-acetylide complex is a convenient
probe for judging the coordination properties of the coordination
sites by taking a look at the σ- and π-coordination.6
Scheme 2
µ-Acetylide complexes with the PNNP ligand (10) are
prepared by treatment of the tetracarbonyl complexes of Ir and
Rh (1 and 2) with lithium acetylide (Scheme 3) in a manner
similar to the previously reported preparation of the (PNNP)-
Rh2 complexes 10aa and 10ab.5 In contrast, for the PNNN
complexes, not all combinations afford the desired µ-acetylide
complexes as stable species, and the preparation is successful
only in the cases of complexes 11aa, 11ab, and 11ca with the
(4) The obtained carbonyl PNNP and PNNN complexes were subjected
to the reactions examined for 1a (e.g. alkyne, hydrosilane),5 but intractable
mixtures of products were obtained, suggesting considerably different
reactivity between the Rh and Ir analogues.
(5) (a) Tanaka, S.; Inagaki, A.; Akita M. Angew. Chem., Int, Ed. 2001,
40, 2865. (b) Tanaka, S.; Dubs, C.; Inagaki, A.; Akita, M. Organometallics
2004, 23, 317. (c) Tanaka, S.; Dubs, C.; Inagaki, A.; Akita, M. Organo-
metallics 2005, 24, 163. (d) Dubs, C.; Inagaki, A.; Akita, M. Chem.
Commun. 2004, 2760.
the half-carbonylated species 8 (Scheme 2) and then to 2c, the
δH(H6-py) signals are shifted from 7.87 ppm (2′c: (N,N)Ir(cod))
to 8.59 ppm (8: (N,N)Ir(CO)2) and then to 8.63 ppm (2c:
(N,N)Ir(CO)2). Therefore, it is concluded that the (N,N)Ir(cod)
part is carbonylated at the stage of 8. On the other hand,
carbonylation of 2′d causes shifts of the H6 signals as follows:
<8 ppm (2′d: overlapped with the other signals; (N,N)Rh(cod))
(6) Lotz, S.; van Rooyen, P. H.; Meyer, R. AdV. Organomet. Chem. 1995,
37, 219.

Ir Complexes with Bridging PNNN and PNNP Ligands
Organometallics, Vol. 25, No. 6, 2006 1361
Figure 1. Molecular structures of (a) 2a, (b) 7, (c) 5, (d) 10ca, and (e) 11ab drawn with thermal ellipsoids at the 30% probability level.
particular Rh(PNNN)M metal arrangement. While the µ-acetyl-
ide complexes appear to be formed for the other cases (11ba
and 11da), they decompose during the isolation process. In
addition, the isolated complexes 11aa and 11ca turn out to be
much less stable than the PNNP complexes 10.
sites cannot be determined by the spectroscopic data alone.
X-ray crystallography reveals that the p-tol-CtC complex 10ca
(Figure 1 and Table 1) has the acetylide ligand σ-bonded to Ir
and π-bonded to Rh. The same coordination feature is also found
for the Me3SiCtC complex 10bb, although the quality of the
crystal is low.8 Comparison of the structures and the 31P NMR
data for the previously reported Rh2 complexes 10a reveals that,
of the two 31P signals for 10ab (observed at -80 °C), the signal
with the larger JRh-P coupling constant appearing at lower field
(δP 55.3 (d, JRh-P ) 159 Hz)) can be assigned to the phosphorus
atom coordinated to the π-bonded Rh center and the other signal
with the smaller JRh-P coupling constant appearing at higher
field (δP 47.3 (d, JRh-P ) 122 Hz)) can be assigned to the
phosphorus atom coordinated to the σ-bonded Rh center (Chart
2). This assignment turns out to be useful in the characterization
of 11ca, as described below.
The obtained µ-acetylide complexes have been characterized
by spectroscopic and crystallographic analyses. The homo-
nuclear Ir2(PNNP) complexes 10b show dynamic behavior via
a windshield wiper like motion, as usually observed for
symmetrical µ-acetylide complexes, including the previously
reported Rh2 analogues 10a.5c When the temperature is lowered,
the symmetrical NMR features change into ones consistent with
an unsymmetrical structure, suggesting that the dynamic be-
havior is frozen out at low temperatures. For example, the single
31P signals for the CtCSiMe3 complexes separate into two
signals below 0 °C (10bb; Ir) and -40 °C (10ab; Rh). When
the separations of the two signals at a slow exchange limit are
taken into account (1296 Hz (10ab; Rh) . 245 Hz (10bb; Ir)),
it is concluded that the activation barrier for the Ir complex is
much higher than that for the Rh complex. The activation
energies at the coalescence temperatures are estimated to be
9.8 kcal mol-1 (10ab; Rh) and 12.5 kcal mol-1 (10bb; Ir).7
In contrast, the heteronuclear complexes 10c are static with
respect to the windshield wiper motion, but the coordination
As for the 13C NMR data, it is difficult to locate the signals
for the CtC part because of their low intensities, owing to
(7) Bovey, F. A.; Jelinski, L.; Mirau, P. A. Nuclear Magnetic Resonance
Spectroscopy, 2nd ed.; Academic: San Diego, CA, 1988.
(8) Because of the low quality of the crystal, the result for 10bb is not
included in this paper. Crystal data for 10bb: triclinic, space group P1h, a
) 17.553(6) Å, b ) 19.473(7) Å, c ) 11.441(4) Å, R ) 98.91(3)°, â )
90.17(2)°, γ ) 65.268(9)°, V ) 3500(2) Å3, Z ) 4, T ) -60 °C.

1362 Organometallics, Vol. 25, No. 6, 2006
Table 1. Selected Structural Parameters for the Carbonyl and µ-Acetylide Complexesa
Dubs et al.
2ab
5
7
10ca
Rh(CO)
Ir(CO)(CtC-p-tol)
11ab
ML
M′L′
X
Rh(CO)2
Rh(CO)2
py
Pd(allyl)
Ir(CO)2
py
Rh(CO)2
Rh(CO)2
py/PdO
Rh(CO)
Rh(CO)(CtCSiMe3)
CH2PPh2
py
M‚‚‚M′
M-P1
M-N1
M′-N2
M′-X
M-L
4.253(1)
2.312(3)
2.084(8)
2.071(7)
2.100(8)
1.86(1) (C01A)
1.92(1) (C02A)
4.336(1)
2.281(2)
2.111(6)
2.042(6)
4.166(2)
3.656(1)
2.284(5)
2.03(1)
2.258(4)
2.08(1)
2.05(2) (C1)
1.62(3) (C02)
3.877(2)
2.236(4)
2.08(1)
1.94(1)
2.063(8) b
2.100(9)
2.058(9)
2.12(1)
1.86(1) (C01B)
1.83(1) (C02B)
2.103(7)
2.13(1)
2.23(1) (C1)
2.14(1) (C2)
2.08(1) (C3)
1.859(9) (C01)
1.871(9) (C02)
2.56(1) (C1)
2.31(1) (C2)
1.83(1) (C01)
2.01(2) (C1)
1.79(2) (C02)
M′-L′
1.84(1) (C03A)
1.86(1) (C04A)
1.85(1) (C03B)
1.86(1) (C04B)
2.32(1) (C1)
2.29(1) (C2)
1.81(2) (C01)
P1-M-N1
80.1(2)
78.4(3)
171.2(6)
159.8(7)
29(1)
80.5(2)
77.9(3)
167.2(5)
162.7(6)
29(1)
88.0(3)
79.7(3)
169.9(7)
171.8(8)
21(1)
80.1(3)
77.2(3)
167(1)
169(1)
0(2)
80.4(3)
77.2(5)
173.6(9)
177(1)
12(2)
N2-M′-X
M-N1-N2-C13
M′-N2-N1-C11
M-N1-N2-M′
a Interatomic distances in Å and bond angles and dihedral angles in deg. b 2a and 7 formed cocrystals.
Scheme 3
Chart 2
complicated coupling with the P and Rh nuclei. However, the
data for the Rh(PNNP)Ir(CtC-p-tol) complex 10ca are com-
parable to those for the previously reported symmetrical Rh2
complex 10ab, as shown in Chart 2. The couplings of the
magnitude of ∼110 Hz can be attributed to JC-P couplings with
the phosphorus atom attached to the σ-bonded Rh center,
because the coupling of J ) 47 Hz disappears upon replacement
of the σ-bound metal (Rh: 10ab f Ir: 10ca). The coupling of
J ) 47 Hz for 10ab is, therefore, attributed to the JRh-C coupling
with the σ-bound Rh center.
The coordination mode of the unstable Rh(PNNN)M complex
11 can be determined by comparison of the 31P NMR data. As
discussed above (Chart 2), the 31P data (δP and JC-P) for 11 are
comparable to those for one of the two types of 31P NMR signals

Ir Complexes with Bridging PNNN and PNNP Ligands
Organometallics, Vol. 25, No. 6, 2006 1363
as determined by ESI-MS and 31P NMR analyses. The het-
erotetranuclear complex 12b has been characterized by spec-
troscopic data, and the arrangement of the metals (M1 ) Rh,
M2 ) Ir) is tentatively assigned according to the tendency
observed for the dinuclear µ-acetylides: Rh prefers the π-co-
ordinating site. The formation of the mixtures (entries 2 and
4-7) should involve dissociation into dinuclear species, where
acetylide transfer to the Rh-containing dinuclear fragment leads
to the formation of 12a and 12b. and the other components
should decompose to give the unidentified products.
Scheme 4
Catalytic Reactions. Polynuclear complexes are expected to
show unique features, which are not observed for mononuclear
complexes, by sharing the functions needed for catalytic
processes. The obtained dinuclear complexes have been sub-
jected to a couple of typical catalytic reactions.
(i) Hydrogenation and Hydroformylation. Catalytic hy-
drogenation of alkenes and alkynes with [(PNNP)Rh2(nbd)2]-
BF4 and 1b was reported by Bosnich, but features peculiar to
the dinuclear systems were not observed.2 All cod complexes
1′ and 2′ show activity for catalytic hydrogenation of diphen-
ylacetylene, and a mixture of cis- and trans-stilbene and 1,2-
diphenylethane is obtained, when the reaction is carried out in
the presence of the catalyst (1 mol %) under an H2 atmosphere
(5 atm) in THF (2 mL; MeOH (0.2 mL) was added to 2′a and
2′b to dissolve them). The order of catalytic activities is as
follows (the numbers given in parentheses are conversion of
diphenylacetylene/yield of cis-stilbene/yield of trans-stilbene/
yield of diphenylethane, in percent): for the PNNP series, 1′b
(100/0/60/39) ≈ 1′c (100/0/60/31) > 1′a (33/27/5/0); for the
PNNN series, 2′b (100/0/53/46) ≈ 2′d (100/0/51/48) > 2′c
(47/40/7/0) > 2′a (8/4/0/0). The hydrogenation proceeds in a
stepwise manner, as confirmed by comparison with hydrogena-
tion of stilbenes (PhCtCPh f cis-PhCHdCHPh f trans-
PhCHdCHPh f PhCH2CH2Ph), and no significant feature
peculiar to the dinuclear systems has been observed, in accord
with the report by Bosnich.
for the PNNP complex 10, i.e., the deshielded signal with a
larger Rh-P coupling constant, indicating that the acetylide
ligand in 11 is π-bonded to the Rh(P,N) part and, as a
consequence, σ-bonded to the M(N,N) center. The molecular
structure of the rather stable homonuclear dirhodium complex
11ab is determined by X-ray crystallography (Figure 1(e)), and
the π-coordination of the (P,N)Rh part rather than the (N,N)Rh
part has been confirmed.
On consideration of the successfully isolated µ-acetylide
complexes, it is noteworthy that, for the series of the PNNP
and PNNN complexes, the µ-acetylide complexes are stable
enough to be isolated only when a Rh(P,N) fragment is π-coor-
dinated to the bridging acetylide ligand. While the Ir(PNNP)Ir
complexes 10b are isolable, they are less stable than the Rh
analogues 10a and, therefore, the yields are modest. Two ways
of back-donation are feasible toward a µ-acetylide ligand: (1)
to the antibonding π*-orbitals of the CtC part, leading to an
η2-coordinated structure, and (2) to the vacant p-orbital of the
R-carbon atom, leading to partial double bond MdCR character.
However, in general, the latter interaction is not as significant
as that of other good π-acceptors such as CO.9 On the other
hand, the P,N-donor set is a better π-donor compared with the
N,N-donor set but, as for the metal center, the general tendency
of the electronic properties of second- and third-row metals is
not straightforward and still controversial.10 Judging from the
results obtained, the π-interaction (1) appears to contribute to
stabilization of the µ-acetylide complex and, therefore, the Rh
center is more π-donating than the Ir center; thus, the π-donating
ability is estimated to be in the order of Rh(P,N) > Ir(P,N) >
M(N,N).
In a previous paper we reported unique tetrarhodium µ4-
acetylide complexes with the PNNP ligand 12, which were
prepared by reaction between 10a and 1a.5 The newly prepared
dinuclear µ-acetylide complexes with the PNNP ligand 10 are
subjected to reaction with 1 (Scheme 4). In this case, too, the
stability of the adducts is dependent on the metal.11 In reactions
of 10 and 1 of the same M1-M2 combination (entries 1-3),
the adducts 12a and 12b are formed, only when Rh is included
in both components (entries 1 and 3), and a mixture of
unidentified products is obtained from 10ba and 1b (entry 2).
For entries 4-7 of different metal combinations, mixtures
containing 12a and/or 12b and unidentified products are formed,
The cod complexes 1′ and 2′ are also effective for hydro-
formylation of 1-octene to give a mixture of nonanal and
2-methyloctanal, with the former being the major product (n/i
≈ 2) when the reaction is conducted for 6 h at 80 °C under a
CO (15 atm)-H2 (15 atm) mixture. The activity determined
on the basis of the conversion of 1-octene is as follows
(the numbers given in parentheses are conversion of 1-oc-
tene/yield of nonanal/yield of 2-methyloctanal, in percent):
1′a (80/41/25) ≈ 2′c (77/42/21) > 2′d (66/44/21) ≈ 1′b
(61/29/11) > 1′c (37/22/11). The Rh-containing complexes
appear to be more active than the Ir-containing ones, but metal
exchange reaction occurs during the catalytic reaction of the
heterometallic complexes, as revealed by ESI-MS analysis of
the reaction mixtures,12 being in accord with the metal exchange
observed for the carbonylation of the cod complexes described
above.
(ii) Catalytic Allylation of Aniline with Allyl Alcohol.
Catalytic allylic substitution has been mediated by a variety of
transition-metal species.13 Although allyl halide and esters have
been used as allylic sources, very few successful direct catalytic
allylations with allyl alcohol have been reported so far, despite
its advantage from the viewpoint of economical and environ-
(9) (a) Lichtenberger, D. L.; Renshaw, S. K.; Wong, A.; Tagge, C. D.
Organometallics 1993, 12, 3522. See also: (b) Lichtenberger, D. L.;
Renshaw, S. K.; Bullock, R. M. J. Am. Chem. Soc. 1993, 115, 3276.
(10) Mingos, D. M. P. Essential Trends in Inorganic Chemistry; Oxford
University Press: Cambridge, U.K., 1998.
(11) From the reactions of the PNNN complexes 11 no characterizable
product could be obtained.
(12) The cod complexes were converted to the corresponding CO
complexes during the hydroformylation.
(13) See for example: Tsuji, J. Transition Metal Reagents and Cata-
lysts: InnoVations in Organic Synthesis; Wiley: New York, 2002. Tsuji,
J. Palladium Reagents and Catalysts: New PerspectiVes for the 21st
Century; Wiley: New York, 2004.

1364 Organometallics, Vol. 25, No. 6, 2006
Dubs et al.
Scheme 5
mental concerns.14 Then the (η3-allyl)Pd-Ir complexes have
been employed as catalysts for allylation of aniline (14). As a
result, all complexes show catalytic activity to give a mixture
of mono- (15) and diallylaniline (16), when the reaction is
carried out for 6 h at 80 °C in the presence of MgSO4 under a
CO atmosphere (1 atm) (Scheme 5). CO appears to suppress
decomposition of the catalytic species and, in entries 2 and 5,
formation of byproducts, which cannot be detected by GLC, is
evident. It is notable that the diiridium complex 1b shows
catalytic activity, though the activity is inferior to that of the
Pd-containing complexes. However, no apparent relationship
between the activity and the coordination sites is observed.
To obtain information of the reaction mechanism at an early
stage, a stoichiometric reaction of the Ir(PNNP)Pd complex 3
with allyl alcohol 13 has been examined (Figure 2). Addition
of 1 equiv of 13 to 3 causes broadening of the 31P NMR signals,
and in particular, the signal for the Ir(PN) part becomes
undetectable (Figure 2b). However, upon further addition of 10
equiv of 13 a broad signal appears around 9 ppm (Figure 2c),
and final treatment with NEt3 gives four pairs of sharp signals
(Figure 2d), which are identical with the spectrum of the product
19 isolated from the mixture. When the reaction is followed by
IR, no apparent change is observed before addition of NEt3,
which causes appearance of a new set of two absorptions. The
four sets of the 31P NMR signals observed for 19 reveal that it
consists of four stereoisomers, which show the same IR features
within the experimental IR resolution, and is tentatively assigned
to the (allyloxy)carbonyl species on the basis of the IR spectrum
containing a terminal CO vibration (1962 cm-1) and an acyl
CdO vibration (1654 cm-1), although NMR characterization
is hampered by the presence of the four isomers. The spectral
changes mentioned above can be interpreted in terms of Scheme
6. Complexes 3 and 13 are in equilibrium with the adduct 18,
and the equilibrium is shifted to the reactant side (3 + 13), but
addition of a large amount of 13 causes an increase of population
of 18 enough for it to appear as a broad signal. The acidic OH
proton in 18 is removed upon addition of NEt3, and the neutral
species 19 is obtained.
Figure 2. Interaction of 3 with allyl alcohol (13) followed by 31
NMR and IR: (a) 3; (b) after addition of 1 equiv of 13; (c) after
addition of 10 equiv of 13; (d) after addition of NEt3.
P
mononuclear mechanism, (2) an Ir-centered mechanism involv-
ing conversion of the (allyloxy)carbonyl-Ir part into a (η3-allyl)-
Ir species, and (3) a dinuclear mechanism, which follows (i)
activation of allyl alcohol via the (allyloxy)carbonyl-Ir species,
(ii) subsequent transfer of the allyl moiety to the Pd center
accompanying C-O bond cleavage, and (iii) reaction at the
resultant (η3-allyl)Pd moiety. Although it is difficult to determine
the mechanism of the present complicated dinuclear system,
the present result suggests that formation of a (η3-allyl)metal
species from allyl alcohol may be promoted by the initial
interaction with the CO ligand (as in 18). C-O bond cleavage
of alcohol is not always a facile process, and dehydration under
acidic conditions is most frequently referred to as the C-O bond
activation method,14 while the ultimate driving force of the
present system is still acid-catalyzed dehydration. The mecha-
nistic study is now under way, with related mononuclear
complexes having the partial structures (with P,N and N,N
chelates) of the dinuclear complexes, and the results will be
reported in a forthcoming paper.
Molecular Structures of Carbonyl and Acetylide Com-
plexes. The carbonyl complexes 2a and 5 and the µ-acetylide
complexes 10ca and 11ab have been characterized by X-ray
crystallography together with complex 7 resulting from the
adventitious P-oxidation (Figure 1 and Table 1).
The absence of metal-metal interaction is evident from the
intermetallic distances (>3.6 Å). All metal centers adopt square-
planar coordination geometries, as usually observed for four-
coordinate d8-metal complexes with 16 valence electrons, and
coordination of the allyl ligand in 5 is unsymmetrical, owing
to the trans effect of the phosphorus atom. Distortion of the
core structures from planar ones is also noted for the carbonyl
complexes 2a, 7, and 5, as observed for the precursors 1′ and
2′. The distortion can be best described by the M-N1-
N2-M′ dihedral angle, and the extent of the distortion is
considerably smaller than that of the cod complexes 1′ and 2′
because of the linear structure of the CO ligands. The
comparable torsion angles for 2a with the five-membered Rh,P-
containing metallacycle and 7 with the six-membered Rh,O,P-
containing metallacycle reveal that the distortion mainly results
from the steric repulsion between the inner ligands not from
the strain of the Rh,P,(O)-containing metallacycle. In con-
trast, the core structures of the µ-acetylide complexes are
The structure of 18 suggests three possible mechanisms for
the subsequent allylation processes: i.e., (1) a Pd-centered
(14) (a) Ozawa, F.; Okamoto, H.; Kawagishi, S.; Yamamoto, S.; Minami,
T.; Yoshifuji, M. J. Am. Chem. Soc. 2002, 124, 10968. (b) Ozawa, F.;
Ishiyama, T.; Yamamoto, S.; Kawagishi, S.; Murakami, H.; Yoshifuji, M.
Organometallics 2004, 23, 1698. (c) Bricout, H.; Carpentier, J,-F.; Mortreux,
A. J. Mol. Catal. A 1998, 136, 242. (d) Sakaibara, M.; Ogawa, A.;
Tetrahedron Lett. 1994, 35, 8015. (e) Yang, S.-C.; Tsai, Y.-C. Organome-
tallics 2001, 20, 763. (f) Tamaru, Y. J. Organomet. Chem. 1999, 576, 215.
(g) Kimura, M.; Futama, M.; Shibata, K.; Tamaru, Y. Chem. Commun. 2003,
234. (h) Garc´ıa-Yebra, C.; Janssen, J. P.; Rominger, F.; Helmchen, G.
Organometallics 2004, 23, 5459.

Ir Complexes with Bridging PNNN and PNNP Ligands
Organometallics, Vol. 25, No. 6, 2006 1365
Scheme 6
JC-P ) 35), 30.6 (td, JC-H ) 135, JC-P ) 29, C6/7), 103.7 (dt,
JC-H ) 189, JC-P ) 11, C4), 126.4-133.3 (d, Ph), 157.8
(br s), 159.4 (br. s, C3/5), the CO peaks could not be located; IR
(KBr) 2074, 2007, 1084 cm-1; ESI-MS m/z 843.0 (M+ - CO),
815.1 (M+ - 2CO), 787.2 (M+ - 3CO). Anal. Calcd for
C33H25N2O4P2IrRhBF4: C, 41.39; H, 2.63; N, 2.93. Found: C,
41.75; H, 3.00; N, 2.92.
virtually planar, because the µ-acetylide ligand occupies the
inner two coordination sites in a µ-η1:η2 fashion. The rather
larger M‚‚‚M separations make the π-coordinating M1-CR
interaction longer than those in M-M-bonded systems. The
M1-CR-Câ triangle in 11ab is much more distorted from
an isosceles triangle than that in 10ca, as can be seen from
(d(M-CR) - d(M-Câ) ) 0.25 Å (11ab) > 0.03 Å (10ca)),
presumably owing to the larger M‚‚‚M separation for 11ab.
Conclusion. The Ir-containing dinuclear cod complexes with
the PNNP and PNNN complexes have been successfully
converted to the corresponding carbonyl complexes by treatment
with CO (1 atm). The obtained carbonyl complexes have been
further converted to the µ-acetylide complexes to examine the
basic coordination properties of the ancillary PNNP and PNNN
ligand, and the properties of the P,N and N,N chelates on
dinuclear complexes have been established. Combined with the
results of the preceding paper,1 a library of Ir-containing homo-
and heterodinuclear complexes have been established, as sum-
marized in Chart 3.
[(CO)2Rh(PNNN)Rh(CO)]BF4 (2a). A CH2Cl2 solution (5 mL)
of 2′a (158 mg, 0.168 mmol) was stirred for 3 h at room temperature
under a CO atmosphere (1 atm). Slow addition of hexane to the
resultant mixture gave a yellow precipitate, which was washed with
ether and dried in vacuo. 2a (yellow solid; 141 mg, 0.168 mmol,
100% yield): δH 3.98 (2H, d, J ) 11.2, H11), 6.75 (1H, s, H4),
7.28-7.57 (m, aromatic), 7.72 (1H, d, J ) 6.8, H7), 7.90 (1H, t, J
) 7.8, H8), 8.40 (1H, br. d, H10); δP (CDCl3) 42.6 (d, JP-Rh
)
126); δC (acetone-d6) 103.4 (m, JC-H ) 174.9, C4), 122.3 (s, JC-H
) 169, C7), 126.0 (d, JC-H ) 170, C9), 129.8-133.5 (Ph), 142.8
(d, JC-H ) 167, C8), 152.8 (s, C3/5/6), 154.0 (d, JC-H ) 184, C10),
156.4 (s), 157.5 (s, C3/5/6), 185.1 (br, CO), 184.4 (br, CO), the
C11 signal was overlapped with the solvent signal; IR (KBr)
2101, 2090, 2039, 2019, 1994, 1610, 1084, 1058 cm-1; ESI-MS
m/z 631.6 (M+ - CO), 575.9 (M+ - 3CO). Anal. Calcd for
C25H17N3O4PRh2BF4: C, 40.20; H, 2.29; N, 5.63. Found: C, 39.96;
H, 2.59; N, 5.38.
The obtained dinuclear complexes serve as catalysts for
alkyne hydrogenation, alkene hydroformylation, and allylation
with allylic alcohol, and a dinuclear mechanism has been
proposed for the allylation, the mechanism of which needs to
be confirmed by further study and will be the subject of a
forthcoming paper.
[(CO)2Ir(PNNN)Ir(CO)2]BF4 (2b). 2b was prepared in a manner
similar to the synthesis of 2a. 2b (196 mg, 0.21 mmol, 100%
yield): δH (CDCl3) 4.19 (2H, d, J ) 10.6, H11), 7.48-8.18 (12H,
m, aromatic), 8.18-8.20 (2H, m, H7/8), 8.56 (1H, d, J ) 5.6, H10);
δP (CDCl3) 36.7; δC (CD2Cl2) 30.5 (td, JC-H ) 136, JC-P ) 34,
Experimental Section
General Methods. All manipulations were carried out under an
inert atmosphere by using standard Schlenk tube techniques. Solvent
purification methods and analytical facilities were the same as those
described in the preceding paper. Chemical shifts and coupling
constants are reported in ppm and in Hz, respectively. The
numbering schemes for the NMR data of the PNNP and PNNN
ligands are shown in Chart 4.
[(CO)2Rh(PNNP)Ir(CO)2]BF4 (1c). A CH2Cl2 solution (3 mL)
of 1′c (146 mg, 0.137 mmol) cooled to 0 °C was stirred under a
CO atmosphere (1 atm) for 90 min. Precipitation with hexane gave
1c as a yellowish brown solid, which was washed with ether. 1c
(132 mg, 0.137 mmol, 100% yield): δH (CDCl3) 4.00 (4H, d, J )
10.8, H6/7), 6.75 (1H, s, H4), 7.5-7.7 (20H, m, Ph); δP (CDCl3)
34.8 (s), 41.0 (d, JP-Rh) 125); δC (CD2Cl2) 30.6 (td, JC-H ) 135,
C11), 104.5 (dd, JC-H ) 183, JC-P ) 10, C4), 122.8 (d, JC-H )
172, C7), 126.2 (d, JC-P ) 59, C12), 126.7 (d, JC-H ) 170, C9),
129.7-133.2 (Ph), 143.2 (d, JC-H ) 170, C8), 152.6 (s, C5/6), 152.7
(d, JC-H ) 187, C10), 159.1 (s, C5/6), 159.8 (d, JC-P ) 4, C3),
171.4 (s), 172.7 (s), 179.0 (br), 180.0 (br, CO); IR (KBr) 2080,
2008, 1615, 1083 cm-1; ESI-MS m/z 838.0 (M+), 810.2 (M+
-
CO), 782.2 (M+ - 2CO), 754.4 (M+ - 3CO). Anal. Calcd for
C27.4H22.6N3O4BF4PIr2 (2b‚0.4(hexane)): C, 34.27; H, 2.37; N, 4.38.
Found: C, 34.23; H, 2.49; N, 4.09.
[(CO)2Rh(PNNN)Ir(CO)2]BF4 (2c). A CH2Cl2 solution (5 mL)
of 2′c (189 mg (0.2 mmol) was stirred for 3 h at 0 °C under a CO
atmosphere (1 atm). Addition of hexane gave a brown solid, which
was collected and carbonylated for 1 h at room temperature.
Precipitation with hexane gave 2c as an orange solid. 2c (168 mg,
0.2 mmol, 100% yield): δH (CD2Cl2) 4.05 (2H, d, J ) 11.0, H11),
7.01 (1H, s, H4), 7.48-7.75 (11H, m, aromatic), 7.97 (1H, d, J )
7.6, H7), 8.19 (1H, td, J ) 8.0, 1.6, H8), 8.63 (1H, d, J ) 5.5,
H10); δP (CD2Cl2) 44.7 (d, JP-Rh ) 126); δC (CD2Cl2) 30.4 (td,
JC-H ) 136, JC-P ) 29, C11), 104.3 (dd, JC-H ) 183, JC-P ) 12,
C4), 122.4 (d, JC-H ) 163, C7), 126.3 (d, JC-H ) 165, C9), 126.6
(d, JC-P ) 51, C12), 129.6-132.8 (Ph), 143.1 (d, JC-H )168, C8),
152.6 (d, JC-H ) 184, C10), 153.0 (s), 156.8 (s), 158.5 (s, C3/5/6),
171.9, 173.5 (s, Ir(CO)), 186 (m, Rh(CO)); IR (KBr) 2962, 2073,
1998, 1083 cm-1; ESI-MS m/z 721.9 (M+ - CO). Anal. Calcd for
C25H17N3O4BF4PRhIr: C, 35.90; H, 2.05; N, 5.02. Found: C, 35.62;
H, 2.49; N, 4.64.
Chart 3
Chart 4
[(CO)2Ir(PNNN)Rh(CO)2]BF4 (2d). 2d was prepared in a
manner similar to the synthesis of 1c. 2d (yellow solid; 100%
yield): δH (CD2Cl2) 4.07 (2H, d, J ) 10.8, H11), 7.04 (1H, s, H4),

1366 Organometallics, Vol. 25, No. 6, 2006
Dubs et al.
7.49 (1H, t, J ) 6.7, H9), 7.52-7.80 (10H, m, aromatic), 7.90 (1H,
d, J ) 8.0, H7), 8.12 (1H, t, J ) 7.8, H8), 8.51 (1H, d, J ) 5.1,
H10); δP (CD2Cl2) 38.8 (s); δC (CD2Cl2) 30.4 (td, JC-H ) 136,
JC-P ) 35, C11), 103.7 (dd, JC-H ) 181, JC-P ) 11, C4), 122.7
(d, JC-H ) 168, C7), 125.9 (d, JC-H ) 176, C9), 129.8-133.2 (Ph),
(M+ - 4CO). Anal. Calcd for C26H22N3O2BF4PPdIr: C, 37.86; H,
2.68; N, 5.09. Found: C, 37.65; H, 2.86; N, 4.95.
(CO)Ir(PNNP)Ir(CO)(µ-CtC-p-tol) (10ba). To a THF solution
(10 mL) of 2 equiv of HCtC-p-tol (36 µL, 0.287 mmol) cooled to
-75 °C was added n-BuLi (1.6 M, 188 µL, 0.300 mmol). After 10
min, 1c (150 mg, 0.140 mmol) dissolved in THF (10 mL) was added
to the resultant solution. The mixture was stirred for 10 min at
-75 °C, for 30 min at 0 °C, and for 1 h at ambient temperature.
The solution was filtered through an alumina pad and concentrated
to 2 mL under reduced pressure. Addition of diethyl ether gave
10ba as a yellow precipitate. 10ba (48 mg, 0.046 mmol, 33%
yield): δH (CD2Cl2) 2.29 (3H, s, Me), 3.88 (4H, d, J ) 10.9, H6/
7), 6.05 (1H, s, H4), 7.10 (4H, d, J ) 12.0, tol), 7.30-7.74 (22H,
142.4 (d, JC-H ) 167, C8), 152.6 (s, C3/5/6), 152.9 (d, JC-H
)
185, C10), 158.1 (s), 159.0 (s, C3/5/6), CO signals could not
be located; IR (KBr): 2086, 2017, 1972, 1084 cm-1; ESI-MS
m/z 721.8 (M+ - CO), 693.9 (M+ - 2CO). Anal. Calcd for
C25H17N3O4BF4PRhIr: C, 35.90; H, 2.05; N, 5.02. Found: C, 35.60;
H, 2.51; N, 4.58.
[(CO)2Ir(PNNP)Pd(allyl)]BF4 (3). 3 was prepared in a manner
similar to the synthesis of 2a. 3 (yellow solid; 100% yield): δH
(CD2Cl2) 2.76 (1H, d, J ) 12.0 Hz, allyl), 3.7-4.2 (6H, m, H6/7
+ allyl), 5.45 (1H, m, allyl), 5.7-5.9 (1H, m, allyl), 6.43 (1H, s,
H4), 7.4-7.8 (20H, m, Ph); δP (CDCl3) 29.5 (s), 35.5 (s); δC
(CD2Cl2) 30.7 (td, JC-H ) 136, JC-P ) 35), 31.0 (td, JC-H ) 133,
JC-P ) 27, C6/7), 52.0 (td, JC-H ) 154, JC-P ) 4, allyl), 82.7 (td,
JC-H ) 156, JC-P ) 29, allyl), 102.7 (dt, JC-H ) 178, JC-P ) 10,
C4), 119.0 (dd, JC-H ) 159, JC-P ) 6, allyl), 126.8-133.6 (Ph),
155.8 (d, JC-P ) 67), 157.3 (d, JC-P ) 5, C3/5), 174.9 (s, CO),
179.8 (br, CO); IR (KBr) 3056, 2925, 2067, 2002, 1959, 1436,
1057 cm-1; ESI-MS m/z 831.3 (M+ - CO). Anal. Calcd for
C34H30N2O2BF4P2PdIr: C, 43.17; H, 3.20; N, 2.96. Found: C,
43.44; H, 3.36; N, 2.82.
m, aromatic); δP (CD2Cl2) 37.0 (s); δC (CD2Cl2) 21.2 (q, JC-H
)
126, Me), 35.4 (td, JC-H ) 134, JC-P ) 33, C6/7), 99.2 (dt, JC-H
) 176, JP-C ) 10, C4), 107.3 (t, J ) 20, C9), 121.6 (t, J ) 57,
C8), 125.5-137.9 (Ph), 153.1 (d, JC-P ) 6, C3/5), 182.0 (d, JC-P
) 9, CO); IR (KBr) 3054, 2918, 2025, 1964, 1505, 1101 cm-1
;
FD-MS m/z 1020 (M+). Anal. Calcd for C40H32N2O2P2Ir2: C, 47.14;
H, 3.17; N, 2.75. Found: C, 46.40; H, 3.31; N, 2.74.
(CO)Ir(PNNP)Ir(CO)(µ-CtCSiMe3) (10bb). 10bb was pre-
pared in a manner similar to the synthesis of 10ba. 10bb (yellow
solid; 53% yield): δH (CD2Cl2) 0.41 (9H, s, SiMe3), 3.95 (4H, d,
J ) 10.6, H6/7), 6.12 (1H, s, H4), 7.45-7.76 (20H, m, Ph); δP
(CD2Cl2) 34.8 (s); δC (CD2Cl2) 1.4 (s, JCdH ) 120, SiMe3), 36.3
(td, JC-H ) 134, JC-P ) 33, C6/7), 99.0 (dd, JC-H ) 176, J ) 9,
C4), 104.7 (s, 9, Câ), 128.7-132.9 (Ph), 155.7 (dt, J ) 13, 9,
C3/5); IR (KBr) 2034, 1973, 1890 cm-1; FD-MS m/z 1001 (M+).
Anal. Calcd for C36H34N2O2SiP2Ir2: C, 43.19; H, 3.42; N, 2.80.
Found: C, 43.46; H, 3.47; N, 2.80.
[(CO)2Ir(PNNN)Pd(allyl)]BF4 (4). 4 was prepared in a manner
similar to the synthesis of 1c. 4 (light brown solid; 100% yield):
δH (CDCl3) 3.26 (1H, d, J ) 12.8, allyl), 3.40 (1H, d, J ) 11.9,
allyl), 4.04 (2H, d, J ) 10.9, H11), 4.17 (1H, d, J ) 6.5, allyl),
4.57 (1H, d, J ) 6.2, allyl), 5.77 (1H, m, allyl), 7.11 (1H, s, H4),
7.35 (1H, t, J ) 7.0, H9), 7.45-8.00 (12H, m, aromatic), 8.53 (1H,
(CO)Rh(PNNP)Ir(CO)(µ-CtC-Tol) (10ca). 10ca was prepared
in a manner similar to the synthesis of 10ba. 10ca (yellow brown
solid; 65% yield): δH (C6D6) 1.93 (3H, s, Me), 3.39 (4H, dd, J )
10.2, 2.9, H6/7), 5.68 (1H, s, H4), 7.3-7.7 (22H, m, aromatic),
d, J ) 5.3, H10); δP (CD2Cl2) 39.0; δC (CD2Cl2) 30.4 (td, JC-H
135, JC-P ) 33, C11), 62.2 (t, JC-H ) 162, allyl), 62.9 (t, JC-H
)
)
161, allyl), 102.1 (dd, JC-H ) 179, JC-P ) 8, C4), 116.8 (d, JC-H
) 163, allyl), 121.8 (d, JC-H ) 169, C7), 124.9 (d, JC-H ) 169,
C9), 129.6-133.0 (Ph), 140.4 (d, JC-H ) 167, C8), 151.7 (s,
C3/5/6), 153.8 (d, JC-H ) 183, C10), 156.4 (s), 157.0 (s, C3/5/6),
179.5 (s), 180.0 (d, JC-P ) 84, CO); IR (KBr) 2070, 2005, 1607,
1451, 1082 cm-1; ESI-MS m/z 710.2 (M+ - CO), 738.1 (M+),
750.8 (M+ - CO + MeCN), eluted with MeCN. Anal. Calcd for
C26H22N3O2BF4PPdIr: C, 37.86; H, 2.69; N, 5.09. Found: C, 38.32;
H, 2.91; N, 4.83.
7.9 (2H, d, J ) 8.2, tol); δP (C6D6) 35.3 (s), 51.6 (d, JP-Rh
)
158); δH (C6D6) 21.4 (q, JC-H ) 125, Me), 35.0 (td, JC-H ) 133,
JC-P ) 28, C7), 35.9 (td, JC-H ) 130, JC-P ) 31, C7), 99.1 (br d,
JC-H ) 170, C4), 105.6 (br, CtCâ), 120.0 (d, JC-P ) 114,
CRtC), 128.7-133.6 (aromatic), 151.7 (d, JC-P ) 7), 155.9 (JC-P
) 12, C6/7), 184.5 (s), 195 (m, CO); IR (KBr) 3052, 2961, 1978,
1946, 1434, 1101 cm-1; FD-MS m/z 930 (M+). Anal. Calcd for
C
40.5H33N2O2P2ClRhIr (10ca‚0.5CH2Cl2): C, 50.03; H, 3.42; N,
2.88. Found: C, 49.84; H, 3.38; N, 2.88.
[(allyl)Pd(PNNN)Ir(CO)2]BF4 (5). 5 was prepared in a manner
similar to the synthesis of 2a. 5 (dark violet solid; 98% yield): δH
(CD2Cl2) 2.77 (1H, d, J ) 12, allyl), 3.90-4.13 (4H, m, allyl +
H11), 5.42 (1H, t, J ) 1.4, allyl), 5.74 (1H, m, allyl), 6.91 (1H, s,
H4), 7.44-7.64 (11H, m, aromatic), 7.90 (1H, d, J ) 8.4, H7),
8.14 (1H, td, J ) 7.6, 1.2, H8), 8.61 (1H, d, J ) 5.2, H10); δP
(CO)Rh(PNNP)Ir(CO)(µ-CtCSiMe3) (10cb). 10cb was pre-
pared in a manner similar to the synthesis of 10ba. 10cb (yellow-
brown solid; 88% yield): δH (acetone-d6) 0.34 (9H, s, SiMe3), 3.90
(2H, d, J ) 10.4), 4.04 (2H, d, J ) 11.1, H6/7), 6.01 (1H, s, H4),
7.4-7.8 (20H, m, Ph); δP (acetone-d6) 39.8 (s), 56.1 (d, JP-Rh
)
160); δC{1H} (C6D6) 2.7 (s, SiMe3), 35.9 (d, JC-P ) 27), 36.3 (d,
JC-P ) 29, C6/7), 99.1 (br, C4), 128.7-135.2 (Ph), 152.4 (d, JC-P
) 9), 156.3 (JC-P ) 8, C3/5), 184.3 (br), 187.7 (br, CO); IR (KBr)
1971, 1940, 1901, 1434, 1100 cm-1; FD-MS m/z 912 (M+).15
(CD2Cl2) 32.1 (s); δC (CD2Cl2) 30.6 (td, JC-H ) 134, JC-P
26, C11), 51.9 (td, JC-H ) 160, JC-P ) 4, allyl), 83.0 (td, JC-H
)
)
154, JC-P ) 29, allyl), 103.9 (dd, JC-H ) 181, JC-P ) 9, C4),
119.4 (dd, JC-H ) 161, JC-P ) 6, allyl), 121.9 (d, JC-H ) 167,
C7), 125.7 (d, JC-H ) 170, C9), 129.5-133.2 (Ph), 142.9 (d, JC-H
) 166, C8), 152.6 (d, JC-H ) 183, C10), 154.1 (s, C5/6), 155.4 (d,
JC-P ) 8, C3), 157.3 (s, C5/6), 172.3 (s), 175.0 (s, CO); IR (KBr)
2067, 2001, 1616, 1461, 1056 cm-1; ESI-MS m/z 738.1 (M+), 698.1
(M+ - allyl), 669.2 (M+ - allyl - CO). Anal. Calcd for
C26H22N3O2BF4PPdIr: C, 37.86; H, 2.68; N, 5.09. Found: C, 37.65;
H, 2.86; N, 4.95.
(CO)Rh(PNNN)Rh(CO)(µ-CtC-p-tol) (11aa). 11aa was pre-
pared in a manner similar to the synthesis of 10ba, and workup
should be done at 0 °C because of its thermal instability. 11aa
(yellow-brown solid; 63% yield): δH (acetone-d6) 2.31 (3H, s, Me),
4.09 (2H, d, J ) 11.3, H11), 6.67 (1H, s, H4), 7.12 (2H, d, tol),
7.34 (1H, t, J ) 3.6, H9), 7.53-7.62 (7H, m, aromatic), 8.00 (1H,
t, J ) 7.8, H8), 7.73-7.89 (6H, m, aromatic), 8.66 (1H, d, J )
5.3, H10); δP (acetone-d6) 58.5 (d, JP-Rh ) 158); δC{1H} (CD2Cl2
[(CO)2Rh(OdPNNN)Rh(CO)2]BF4 (7). A CD2Cl2 solution of
1a was stirred under an O2 atmosphere (1 atm) for 1 day, and a
at 0 °C) 21.1 (s, Me), 34.0 (d, JC-P ) 28, C11), 99.2 (d, JC-P
)
12, C4), 120.2 (s, C7), 123.4 (s, C9), 126.7-136.5 (aromatic), 137.8
(s, C8), 151.8 (s, C3/5/6), 153.0 (s, C10), 153.9 (s, C3/5/6), 192.4
(dd, JC-Rh ) 66, JC-P ) 13), 193.8 (d, JC-Rh ) 7, CO); IR (KBr)
1
complete conversion to 7 was confirmed by H and 31P NMR. 7:
δH (CD2Cl2) 4.23 (2H, d, H11), 6.97 (1H, s, H4), 7.3-7.8 (12 H,
aromatic), 8.06 (1H, t, J ) 7.8, H8), 8.47 (1H, d, J ) 5.2, H10);
δP (CD2Cl2) 37.2 (s); IR (KBr) 2084, 2016, 1083 cm-1; ESI-MS
m/z 675.8 (M+), 647.5 (M+ - CO), 619.8 (M+ - 2CO), 564.2
(15) Because of the instability of the complexes satisfactory 13C NMR
data and elemental analyses have not been obtained.

Ir Complexes with Bridging PNNN and PNNP Ligands
Table 2. Crystallographic Data
Organometallics, Vol. 25, No. 6, 2006 1367
2a/7a
10ca
11ab
5
6
solvate
formula
formula wt
cryst syst
space group
a/Å
CH2Cl2
3C6H6
CH2Cl2
C27H24N3O2BF4PCl2PdIr
4CHCl3
C51H36N6O9B2F8P2Cl2Rh4
1594.96
triclinic
P1h
9.990(4)
13.054(3)
22.616(8)
90.35(2)
99.879(7)
96.11(2)
2888(1)
2
C58H50N2O2P2RhIr
1164.12
triclinic
P1h
12.835(9)
14.471(8)
15.382(8)
63.10(2)
89.46(3)
86.39(3)
2542(2)
2
C28H26N3O2SiPRh2
701.40
monoclinic
P21/c
13.491(8)
11.856(3)
17.317(10)
90
102.72(1)
90
2701(2)
4
1.724
1.353
16 544
C52H48N2O4B2F8P2Cl12Ir2
1810.39
triclinic
P1h
13.235(7)
14.245(9)
19.86(1)
105.27(2)
106.60(2)
98.09(2)
3366(3)
2
909.81
monoclinic
P21/c
9.239(7)
9.09(1)
36.77(2)
90
96.01(9)
90
3069(4)
4
b/Å
c/Å
R/deg
â/deg
γ/deg
V/Å3
Z
d
calcd/g cm-3
1.834
1.353
19 839
1.521
3.052
6484
1.968
5.209
7930
1.786
4.548
21 506
µ/mm-1
no. of diffractions
collected
no. of variables
R1 for data with
I > 2σ(I)
757
521
334
368
757
0.0866 (for
6774 data)
0.2329 (for all
11 387 data)
0.0703 (for
2757 data)
0.1817 (for all
5302 data)
0.0711 (for
1961 data)
0.2125 (for all
5925 data)
0.0438 (for
4568 data)
0.1599 (for all
7028 data)
0.0622 (for
8941 data)
0.1691 (for all
13 065 data)
wR2
a 2a and 7 formed cocrystals.
1980 cm-1; Anal. Calcd for C33H26N3O2PCl2Rh2 (11aa‚CH2Cl2):
Allylation of Aniline Giving Mono- and Diallylaniline. A 50
mL Schlenk tube was charged with aniline (1 mmol), allyl alcohol
(4 mmol), MgSO4 (250 mg), cumene (10 µL), catalyst (0.02 mmol),
and THF (2 mL). After two freeze-pump-thaw cycles the mixture
was heated under CO (1 atm) for 6 h at 80 °C. Products were
identified and quantified by GC-MS analysis.
C, 49.28; H, 3.26; N, 5.22. Found: C, 49.23; H, 3.39; N, 5.07.
(CO)Rh(PNNN)Rh(CO)(µ-CtCSiMe3) (11ab). 11ab was pre-
pared in a manner similar to the synthesis of 11aa. 11ab (yellow-
brown solid; 46% yield): δH (acetone-d6) 0.33 (9H, s, SiMe3), 4.04
(2H, d, J ) 11.3, H11), 6.65 (1H, s, H4), 7.52-7.88 (12H, m,
aromatic), 8.00 (1H, t, J ) 7.8, H8), 8.56 (1H, d, J ) 5.3, H10);
δP (acetone-d6) 58.2 (d, JP-Rh ) 163); δC {1H} (CD2Cl2) 1.8 (s,
C16), 34.2 (d, JC-P ) 28, C11) 98.9 (d, JC-P ) 11, C4), 120.1
(s,C7), 123.4 (s, C9), 128.7-132.9 (Ph), 138.0 (s, C8), 152.2 (s,
C3/5/6), 152.8 (s, C10), 153.8 (s, C3/5/6), 193 (br, CO); IR (KBr)
X-ray Crystallography. Single crystals of 2a‚CH2Cl2,
5‚CH2Cl2, and 11ab were obtained by recrystallization from CH2-
Cl2, 6 from CHCl3, and 10ca‚3C6H6 from C6H6. The experimental
procedures were the same as those described in the preceding paper.
Diffraction measurements, except for 5, were made on a Rigaku
RAXIS IV imaging plate area detector with Mo KR radiation (λ )
0.710 69 Å) at -60 °C. For the data collection of 5, diffraction
measurements were made on a Rigaku AFC7R automated four-
circle diffractometer by using graphite-monochromated Mo KR
radiation (λ ) 0.710 69 Å) at room temperature. Crystallographic
data for 2a/7, 10ca, 11ab, 5, and 6 are given in Table 2.
Unless otherwise stated, all non-hydrogen atoms were refined
anisotropically, methyl hydrogen atoms were refined using riding
models, and other hydrogen atoms were fixed at the calculated
positions. For 5, the CH2Cl2 solvate molecule was refined with
isotropic thermal parameters and two components for the central
carbon atom were considered (C51:C52 ) 0.5:0.5). Hydrogen atoms
attached to the CH2Cl2 molecule were not included in the refine-
ment. For 10ca, the disordered phenyl group (C51-C56) was
refined with isotropic thermal parameters by taking into account
two components (C52-C53-C55-C56:C52A-C53A-C55A-
C56A ) 0.523:0.477). Two of the three benzene solvate molecules
were refined isotropically. Hydrogen atoms attached to the disor-
dered part and the solvate molecules were not included in the
refinement.
1975, 1891, 1607 cm-1 15
.
(CO)Rh(PNNN)Ir(CO)(µ-CtC-p-tol) (11ca). 11ca was pre-
pared in a manner similar to the synthesis of 10ba. 11ca (yellow
solid; 35% yield): δH (C6D6) 1.98 (3H, s, Me), 3.38 (2H, d, J )
9.4, H11), 5.82 (1H, s, H4), 5.98 (1H, t, J ) 6.1, H9), 6.7-7.8
(aromatic), 8.16 (2H, d, J ) 7.8, tol); δP (C6D6) 53.0 (d, JP-Rh
)
161); δC decomposed during data collection.15
[(µ-CtC-p-tol){(CO)Rh(PNNP)Ir(CO)}2]BF4 (12b). To a
CH2Cl2 solution (5 mL) of 10cb (43.4 mg, 0.0475 mmol) cooled
to 0 °C was added 1c (45 mg, 0.0475 mmol) slowly as a solid.
After the solution was stirred for 1 h at 0 °C, ether was slowly
added to give a red solid, which was collected, washed with ether,
and dried in vacuo. 12b (81 mg, 0.0442 mmol, 93% yield): δH
(acetone-d6) 2.24 (s, 3H, Me), 3.9-4.4 (m, 8H, H6 + H7), 6.36 (s,
2H, H4), 6.78 (d, J ) 8.2, 2H, tol), 7.4-7.9 (m, 42H, aromatic);
δP (acetone-d6) 44.7 (s), 58.5 (d, JRh-P ) 197); δC (acetone-d6)
21.2 (s, Me), 32.2 (d, JC-P ) 36), 33.0 (d, JC-P ) 29, C6/7), 100.7
(t, JC-P ) 12, C4), 117.3 (d, JC-P ) 96, CR), 128.6-135.6
(aromatic), 154.0 (s), 156.0 (C3/5), 176.7 (bs, CO), 191.6 (dd, JRh-C,
) 67, 13, CO); IR (KBr) 1976, 1633, 1084 cm-1; ESI-MS:
P-C
m/z 1744.9 (M+).15
Acknowledgment. We are grateful to the Ministry of
Education, Culture, Sports, Science and Technology of the
Japanese Government and the Japan Society for Promotion of
Science and Technology for financial support of this research.
A Monbukagakusho scholarship for C.D. from the Japanese
Government is gratefully acknowledged.
Hydrogenation of Diphenylacetylene. A glass autoclave was
charged with diphenylacetylene (1 mmol), catalyst (0.01 mmol),
cumene (10 µL), and THF (2 mL). After two freeze-pump-thaw
cycles H2 was pressurized to 5 atm. Products were identified and
quantified by GC-MS analysis.
Hydroformylation of 1-Octene. A stainless autoclave was
charged with 1-octene (1 mmol), cocatalyst (0.02 mmol), cumene
(10 µL), and THF (2 mL). After two freeze-pump-thaw cycles
H2 (15 atm) and CO (15 atm) was pressurized. The autoclave was
heated for 6 h at 80 °C. Products were identified and quantified by
GC-MS analysis.
Supporting Information Available: Tables and figures giving
crystallographic results (11 pages); data are also available as CIF
files. This material is available free of charge via the Internet at
http://pubs.acs.org.
OM050897E