Synthesis and solid state characterization of a meridional triphos iridium metallacycle-carbene complex: [{PhP(CH2CH2PPh2)2} Ir(CR=CRCR=CR){=C(CH2)3O}][BF4] (R = Co2Me)

Article abstract of DOI:10.1021/om000848w

The five-coordinate iridium metallacycle [(PPh₃)₂Ir(CR=CRCR=CR)(Cl)] (5, R = CO₂CH₃) and trisphosphine [PhP(CH₂CH₂PPh₂)₂] are readily converted in refluxing toluene to the fac- and mer-triphos metallacyclopentadiene complexes [{PhP(CH₂CH₂PPh₂)₂}-Ir(CR=CRCR=CR)Cl ] (6-fac and 6-mer). Halide abstraction from the facial isomer 6-fac gives the isolable cationic solvate [{PhP(CH₂CH₂PPh₂)₂}Ir(CR=CR-CR=CR)(C lCH₂Cl)]BF₄ (7, R = CO₂CH₃) which adopts a mergeometry. Reaction of 7 with carbon monoxide generates the mer isomer of [{PhP(CH₂CH₂PPh₂)₂}Ir(CR=CRCR=CR)(CO )] BF₄ (8, R = CO₂CH₃); whereas, reaction of 7 with 3-butyn-1-ol gives the mer-carbene complex [{PPh(CH₂CH₂PPh₂)₂}Ir(CR=CRCR=CR)(=C OCH₂CH₂CH₂)]BF₄ (9, R = CO₂CH₃). A single-crystal X-ray crystallographic analysis of 9 represents the first solid-state characterization of a meridional [PhP(CH₂CH₂PPh₂)₂] iridium complex.

Full text of DOI:10.1021/om000848w

1482
Organometallics 2001, 20, 1482-1485
Syn th esis a n d Solid Sta te Ch a r a cter iza tion of a
Mer id ion a l Tr ip h os Ir id iu m Meta lla cycle-Ca r ben e
Com p lex: [{P h P (CH2CH2P P h 2)2}
Ir (CRdCRCRdCR){)C(CH2)3O}][BF 4] (R ) Co2Me)
J oseph M. O’Connor,* Kristin Hiibner, Adam Closson, and Peter Gantzel
Department of Chemistry and Biochemistry (0358), University of California at San Diego,
9500 Gilman Drive, La J olla, California 92093-0358
Received October 3, 2000
Summary: The five-coordinate iridium metallacycle
[(PPh3)2Ir(CRdCRCRdCR)(Cl)] (5, R ) CO2CH3) and
trisphosphine [PhP(CH2CH2PPh2)2] are readily con-
verted in refluxing toluene to the fac- and mer-triphos
metallacyclopentadiene complexes [{PhP(CH2CH2PPh2)2}-
Ir(CRdCRCRdCR)Cl] (6-fac and 6-mer). Halide ab-
straction from the facial isomer 6-fac gives the isolable
cationic solvate [{PhP(CH2CH2PPh2)2}Ir(CRdCR-CRd
CR)(ClCH2Cl)]BF4 (7, R ) CO2CH3) which adopts a mer-
geometry. Reaction of 7 with carbon monoxide generates
the mer isomer of [{PhP(CH2CH2PPh2)2}Ir(CRdCRCRd
CR)(CO)] BF4 (8, R ) CO2CH3); whereas, reaction of 7
with 3-butyn-1-ol gives the mer-carbene complex [{PPh-
(CH2CH2PPh2)2}Ir(CRdCRCRdCR)(dCOCH2CH2CH2)]-
BF4 (9, R ) CO2CH3). A single-crystal X-ray crystallo-
graphic analysis of 9 represents the first solid-state
characterization of a meridional [PhP(CH2CH2PPh2)2]
iridium complex.
lowed by proton transfer to the â-carbon. Complex 4 may
arise via the fulvene intermediate II, which in turn may
have resulted from insertion of a vinylidene ligand into
the metallacycle ring.
The results shown in Scheme 1 for the reactions of
iridacyclopentadiene complexes 1 and 3 with 3-butyn-
1-ol demonstrate a dramatic effect on reaction outcome
upon going from the bis(phosphine)/CO coordination
environment to a tris(phosphine) ligation. In addition
to a more electron rich metal center in 3, the labile
coordination site is trans to a phosphine ligand in 3;
whereas, in 1 the alkyne substrate coordinates trans to
one of the metallacycle carbons. In an effort to prepare
a fac-triphos analogue of 3 for which the reactive
coordination site would be trans to a better donor
(dialkyl-substituted phosphine) ligand, we set out to
prepare bis(2-diphenylphosphinoethyl)phenylphosphine
analogues of 3. Complexes of [PPh(CH2CH2PPh2)2] are
known to adopt either fac- or mer-coordination geom-
etries, as compared to [MeC(CH2PPh2)3] for which only
a fac tridentate coordination geometry is possible.3
Although [PPh(CH2CH2PPh2)2] complexes of iridium are
rare,4 both five coordinate fac iridium(I) and six-
coordinate fac iridium(III) complexes have been previ-
ously characterized by X-ray crystallography.4a,b
Iridium metallacyclopentadiene complexes exhibit a
rich reactivity toward terminal alkynes.1,2 For ex-
ample, [(PPh3)2Ir(CRdCRCRdCR)(CO)(NCMe)][BF4]
(1, R ) CO2CH3) undergoes reaction with 3-butyn-1-ol
to give metallacyclopentadiene-carbene complex 2;2a
whereas, the triphos metallacycle [{CH3C(CH2PPh2)3}-
Ir(CRdCRCRdCR)(NCMe)]BF4 (3, R ) CO2CH3) un-
dergoes reaction with 3-butyn-1-ol to give the π-allyl
complex 4 (Scheme 1).2j The oxacyclopentylidene ligand
in 2 presumably arises via formation of a vinylidene
ligand (I), which is trapped by attack of the pendant
hydroxyl substituent at the vinylidene R-carbon, fol-
When the iridium(III) metallacycle chloride 51a (1.8
mmol, 15.0 mM) and bis(2-diphenylphosphinoethyl)-
phenylphosphine (2.3 mmol, 19.2 mM) were heated in
toluene at reflux for 24 h a light-colored precipitate of
[{PhP(CH2CH2PPh2)2}Ir(CRdCRCRdCR)Cl] (6-fac) was
formed and isolated in 65% yield (Scheme 2). Slow
evaporation of the filtrate led to isolation of a small
amount of orange crystalline [{PhP(CH2CH2PPh2)2}-
(1) (a) Collman, J . P.; Kang, J . W.; Little, W. F.; Sullivan, M. F.
Inorg. Chem. 1968, 7, 1298. (b) Chin, C. S.; Lee, H.; Oh, M. Organo-
metallics 1997, 16, 816-818. (c) Chin, C. S.; Park, Y.; Kim, J .; Lee, B.
J . Chem. Soc., Chem. Commun. 1995, 1495. (d) J un, C. H.; Crabtree,
R. H. Tetrahedron Lett. 1992, 33, 7119. (e) Bianchini, C.; Graziani,
M.; Kaspar, J .; Meli, A.; Vizza, F. Organometallics 1994, 13, 1165. (f)
Le, T. X.; Selnau, H. E.; Merola, J . S. J . Organomet. Chem. 1994, 468,
257.
(2) (a) O’Connor, J . M.; Pu, L.; Rheingold, A. L. J . Am. Chem. Soc.
1987, 109, 7578. (b) O’Connor, J . M.; Pu, L.; Rheingold, A. L. J . Am.
Chem. Soc. 1989, 111, 4129. (c) O’Connor, J . M.; Pu, L.; Chadha, R.
Angew. Chem., Int. Ed. Engl. 1990, 29, 543. (d) O’Connor, J . M.; Pu,
L.; Rheingold, A. L. J . Am. Chem. Soc. 1990, 112, 6232. (e) O’Connor,
J . M.; Pu, L. J . Am. Chem. Soc. 1990, 112, 9013. (f) O’Connor, J . M.;
Pu, L.; Chadha, R. K. J . Am. Chem. Soc. 1990, 112, 9627. (g) O’Connor,
J . M.; Pu, L.; Rheingold, A. L. J . Am. Chem. Soc. 1990, 112, 9663. (h)
O’Connor, J . M.; Hiibner, K.; Rheingold, A. L. J . Chem. Soc., Chem.
Commun. 1995, 1209. (i) O’Connor, J . M.; Hiibner, K.; Merwin, R.;
Pu, L.; Rheingold, A. L. J . Am. Chem. Soc. 1995, 117, 8861. (j)
O’Connor, J . M.; Hiibner, K.; Merwin, R.; Gantzel, P.; Rheingold, A.
L., Fong, B. S. J . Am. Chem. Soc. 1997, 119, 3631.
Ir(CRdCRCRdCR)Cl] (6-mer, 5% yield, Scheme 2). The
structural assignments for 6 are based primarily on
NMR spectroscopy. The 31P{1H} NMR spectra (CDCl3)
exhibited two 31P{1H} NMR signals for each isomer: δ
56.06 (t, J ) 7 Hz), -0.63 (d, J ) 7 Hz) for 6-fac, and δ
58.27 (t, J ) 8 Hz), 1.60 (d, J ) 8 Hz) for 6-mer. A second
(unobserved) fac arrangement of the triphos ligand
(3) Mayer, H. A.; Kaska, W. C. Chem. Rev. 1994, 94, 1239.
(4) (a) J ohn, K. D.; Salazar, K. V.; Scott, B. L.; Baker, R. T.;
Sattelberger, A. P. Chem. Commun. 2000, 581. (b) Gull, A. M.; Fanwick,
P. E.; Kubiak, C. P. Organometallics 1993, 12, 2121. (c) Arpac, E.;
Dahlenburg, L. Chem. Ber. 1985, 118, 3188. (d) Arpac, E.; Dahlenburg,
L. J . Organomet. Chem. 1984, 277, 127.
10.1021/om000848w CCC: $20.00 © 2001 American Chemical Society
Publication on Web 03/02/2001

Notes
Organometallics, Vol. 20, No. 7, 2001 1483
Sch em e 1
Sch em e 2
would have exhibited three phosphorus signals in the
31P{1H} NMR spectrum.
7 a band at 1062 cm-1 is consistent with a noncoordi-
nated BF4 counterion.6
Complex 6-fac has a vertical plane of symmetry
bisecting the two PPh2 groups and the metallacycle,
resulting in two resonances for the methyl ester hydro-
A priori it is difficult to predict the relative electronic
effect at the substitutionally labile coordination sites in
3 and 7. The [PhP(CH2CH2PPh2)2] ligand in 7 is
expected to be a better donor than the [CH3C(CH2-
PPh2)3] ligand in 3; however, the labile site is trans to
phosphorus in 3 and trans to a metallacycle carbon in
7. We therefore prepared the corresponding carbon
monoxide complexes from 3 and 7. Exposure of meth-
ylene dichloride solutions of cation 7 to one atmosphere
of carbon monoxide at room temperature led to forma-
tion of the mer carbon monoxide complex 8, which was
isolated as an off-white solid in 78% yield. The mer
formulation for 8 is consistent with the observation of
1
gens in the H NMR spectrum (CDCl3) at δ 3.31 (s, 6H)
and 2.52 (s, 6H). The minor isomer, 6-mer, has a
horizontal symmetry plane equating the two PPh2
groups but leaving the metallacycle with nonequivalent
methyl esters, as indicated by four methyl ester reso-
nances in the 1H NMR spectrum (CDCl3) at δ 3.76, 3.50,
3.31, and 3.19.
The formation of both the fac- and mer-isomers of 6
held out hope that halide abstraction would give fac-
and mer-isomers of the corresponding Ir(III) cations.
However, treatment of either 6-mer or 6-fac (0.60 mmol,
12.0 mM) with AgBF4 (0.66 mmol, 13.2 mM) gave [{PhP-
(CH2CH2PPh2)2}Ir(CRdCRCRdCR)(ClCH2Cl)]BF4 (7)
in 87% isolated yield. The 31P{1H} NMR spectra (CDCl3)
exhibited phosphorus signals at δ 62.87 (t, J ) 8.4 Hz,
1P) and 12.97 (br s, 2P), and the 1H NMR spectra
(CDCl3) of 7 exhibited four methyl singlets at δ 3.89,
3.47, 3.34, and 2.41. The presence of the methylene
dichloride ligand was supported by a two-proton singlet
1
four 3H methyl ester singlets in the H NMR spectrum;
and a triplet at δ 75.24 (J ) 11 Hz, 1P) and a doublet
at δ 19.45 (J ) 11 Hz, 2P) in the 31P{1H} NMR spectrum
(CDCl3). In the IR spectrum of 8, ν(CtO) is observed
at 2069 cm-1. For comparison, the fac triphos carbonyl
complex [{MeC(CH2PPh2)3}Ir(CRdCRCRdCR)(CO)]BF4
(11) exhibits ν(CtO) in the IR spectrum (KBr) at
2094 cm-1.7 The 25 cm-1 lower wavenumber stretch for
1
in the H NMR spectrum (CDCl3) at δ 5.47, as well as
(5) For an iridium(III) methylene dichloride complex, see: Arndtsen,
B. A.; Bergman, R. G. Science 1995, 270, 1970.
(6) Beck, W.; Su¨nkel, K. Chem. Rev. 1988, 88, 1405 and references
therein.
by combustion analysis. The hydrogen chemical shift for
the hydrogens of noncoordinated CH2Cl2 is observed at
δ 5.30 in CDCl3 solvent.5 In the IR spectrum (Nujol) of
(7) O′Connor, J . M.; Closson, A., unpublished result.

1484 Organometallics, Vol. 20, No. 7, 2001
Notes
Ta ble 1. Selected Bon d Dista n ces (Å) a n d An gles
(d eg) for 9
Bond Distances, Å
A
B
distance
A
B
distance
Ir
Ir
Ir
C(35)
C(36)
C(38)
C(40)
P(1)
P(3)
C(39)
C(36)
C(37)
O(1)
2.368(5)
2.359(5)
Ir
Ir
Ir
C(35)
C(37)
C(39)
C(41)
P(2)
2.324(6)
C(35)
C(42)
O(1)
C(38)
C(40)
C(42)
2.045(14)
2.097(17)
1.343(17)
1.541(28)
1.367(23)
1.343(14)
2.131(12)
1.422(28)
1.519(17)
1.493(19)
1.482(25)
C(41)
Bond Angles (deg)
A
B
C
angle
A
B
C
angle
P(1)
Ir
Ir
Ir
Ir
Ir
Ir
P(2)
P(3)
C(35) 88.0(4)
C(35) 90.2(4)
C(39) 98.6(6)
C(42) 176.0(4) P(3)
C(42) 93.2(6)
C(39) 169.2(7) Ir
82.1(2)
165.7(2) P(2)
P(2)
Ir
Ir
Ir
Ir
Ir
Ir
P(3)
83.7(2)
P(1)
P(1)
P(3)
P(2)
P(2)
C(35) 90.3(5)
C(39) 99.4(4)
C(39) 84.6(4)
C(42) 96.2(3)
C(42) 98.1(3)
C(42) 78.1(7)
C(1) 121.4(4)
P(1)
P(3)
P(1)
C(35) Ir
C(35) Ir
C(39) Ir
P(1)
Ir
C(35) C(36) 134.4(10) Ir
C(35) O(1) 117.4(12)
C(36) C(35) O(1) 108.2(11) C(35) C(36) C(37) 108.4(16)
C(36) C(37) C(38) 99.2(12) C(37) C(38) O(1) 102.4(12)
F igu r e 1. Ortep drawing for (9), C50H51IrO9P3BF4.
C(35) O(1) C(38) 111.3(14) Ir
C(39) C(40) C(41) 116.3(11) C(40) C(41) C(42) 115.4(14)
Ir C(42) C(41) 116.3(13)
C(39) C(40) 113.7(13)
ν(CtO) in 8 relative to 11 is indicative of greater back-
bonding to CO in the mer complex 8 relative to that in
fac-11.
Whereas the cationic [MeC(CH2PPh2)3] complex 3
undergoes reaction with 3-butyn-1-ol to give the allyl
complex 4 (Scheme 1), the [PhP(CH2CH2PPh2)2] cation
7 undergoes reaction with 3-butyn-1-ol to give the
oxacyclopentylidene complex [{PhP(CH2CH2PPh2)2}
carbon-carbon bond distances of the metallacycle in 9
are consistent with the presence of a conjugated 1,3-
diene: C(39)-C(40), 1.343 Å, C(40)-C(41), 1.482 Å, and
1.367 Å. The iridium-phosphorus distances in 9 are
2.368(5) Å and 2.359(5) Å for the trans phosphines, and
2.324(6) Å for the central phosphorus which is trans to
a metallacycle carbon.
Ir(CRdCRCRdCR)(dC(CH2)3O)]BF4 (9, R ) CO2CH3)
(Scheme 2). Thus, addition of 3-butyn-1-ol (28 mM) to
a chloroform solution of 7 (20 mM) at room temperature
gave carbene 9 as an analytically pure peach-colored
solid in 67% yield. Two 31P{1H} NMR signals are
observed for 9 at δ 79.27 (br s, 1P) and 10.57 (br s, 2P),
and in the 1H NMR spectrum (CDCl3) four methyl
singlets at δ 3.79, 3.46, 3.38, and 2.36. These data
supports a formulation with a plane of symmetry
through the metallacycle, but with no symmetry plane
perpendicular to the metallacycle. The sp2-carbene
carbon was observed in the 13C{1H} NMR spectrum
(CDCl3) as a broad singlet at δ 282.7. For comparison,
the carbene carbon of 2 gave rise to a broad singlet at
δ 278.3 in the 13C{1H} NMR spectrum.
X-ray data was acquired on a pale yellow obelisk-
shaped crystal of 9, obtained by slow diffusion from
CH2Cl2/Et2O. The structure, as shown in Figure 1, is
consistent with that deduced from the NMR spectros-
copy data. Selected bond distances and bond angles are
summarized in Table 1. The complex deviates from ideal
octahedral geometry with the C(39)-Ir-C(42) angle
constrained by the metallacycle ring to 78.1(7)°. The
2-oxacyclopentylidene ligand mean plane bisects the
metallacycle plane at an angle of 33.8°, which compares
with a 24° angle in 2. Presumably the carbene ligand
rotates more in 9 than in 2 in order to relieve steric
congestion arising from the cis-phosphine ligand of 9.
The Ir-C(35) distance of 2.045(14) Å (compared to
2.025(7) Å for 2) is consistent with a metal-carbon
double bond. The metallacycle iridium-carbon distances
of 2.131(12) and 2.097(17) Å are similar to the corre-
sponding 2.108(7) and 2.101(7) Å distances in 2. The
Con clu sion
Reaction of the bis(triphenylphosphine)iridacyclo-
pentadiene complex 5 with [PhP(CH2CH2PPh2)2] gives
predominantly the fac-metallacycle complex, 6-fac, along
with a minor amount of the mer-isomer. Halide abstrac-
tion from 6-fac, however, leads only to the mer isomer
of the cationic iridacyclopentadiene 7. Whereas the
cationic [MeC(CH2PPh2)3] triphos complex 3 undergoes
reaction with 3-butyn-1-ol to give a π-allyl complex 4,
the [PhP(CH2CH2PPh2)2] triphos complex 7 forms the
oxacyclopentylidene complex 9 upon reaction with 3-bu-
tyn-1-ol. We conclude that the differing reactivity
toward alkynol previously observed for 1 and 3 (Scheme
1) is primarily the result of the geometric factors and
not the greater electron density at the metal center in
intermediates derived from 3 relative to those derived
from 1. The solid-state structure of 9 is the first such
structure to be reported for a mer iridium complex of
[PhP(CH2CH2PPh2)2].
Exp er im en ta l Section
Gen er a l. The iridium starting complex 5 was prepared as
described in the literature.1a Bis(2-diphenylphosphinoethyl)-
phenylphosphine and 3-butyn-1-ol were obtained from Aldrich
Chemical Co. IR spectra were recorded on a Matteson Instru-
ments Galaxy Series 2020 FT-IR spectrometer. 1H and 31P
NMR spectra were obtained on a GE QE 300, Varian Hg 300,
or Varian Hg 400 (1H 300 MHz, 31P, 122 MHz) spectrometer.
13C NMR spectra were obtained on a Varian UNITY 500 (126
MHz) spectrometer. 1H and 13C NMR chemical shifts were
referenced to residual protio-solvent signal, and 31P NMR

Notes
Organometallics, Vol. 20, No. 7, 2001 1485
chemical shifts were referenced to external 85% H3PO4.
Melting point determinations were performed on an Electro-
thermal melting point apparatus and were determined in an
open capillary. FAB mass spectra were performed at the
University of California, Riverside Mass Spectroscopy Facility.
Elemental analyses were performed by Desert Analytics,
NuMega Resonance Labs, or Galbraith Laboratories, Inc.
H), 7.47 (m, 10 H), 7.36 (m, 2 H), 7.29 (m, 4 H), 7.24 (t, 1 H,
J ) 8.5 Hz), 7.11 (t, 2 H, J ) 9.5 Hz), 6.88 (dd, 2 H, J ) 13.5,
2 Hz), 3.92 (br s, 2 H), 3.86 (s, 3H), 3.54 (s, 3 H), 3.48 (s, 3 H),
3.45 (br s, 1 H), 3.32 (s, 3 H), 3.09 (sept, 5 H, J ) 11 Hz).
Anal. Calcd for C47H45P3O9IrBF4: 50.14% C, 4.03% H. Found:
50.18% C, 4.17% H.
[{P P h (CH 2CH 2P P h 2)2}Ir (CR dCR CR dCR )(dCOCH 2-
[{P P h (CH2CH2P P h 2)2}Ir (CRdCR-CRdCR)Cl] (6-fa c, R
) CO2CH3). A 250 mL round-bottom flask was charged under
CH2CH2)]BF 4 (9, R ) CO2CH3). The cationic metallacycle 7
(607 mg, 0.513 mmol) was placed in a 50 mL round-bottom
flask, and dry degassed CHCl3 (25 mL) was transferred to the
flask under vacuum. 3-Butyn-1-ol (52 mL, 0.692 mmol) was
added at -78 °C, and the solution was degassed several times.
After stirring at room temperature for 5 h, the solvent was
removed in vacuo. The residue was dissolved in CHCl3 (20 mL)
and filtered. The filtrate was then concentrated, and Et2O was
added to precipitate 9 as peach-colored powder (400 mg, 67%
yield). mp: 238-240 °C; IR(KBr): 1718(vs), 1699(vs) cm-1; 1H
NMR (CD2Cl2, 300 MHz): δ 7.55-7.33 (m, 26 H), 7.18 (m, 4H),
4.23 (t, 2H, J ) 8.06 Hz), 3.79 (s, 3H), 3.58 (m, 2H), 3.46 (s,
3H), 3.38 (s, 3H), 3.14-2.86 (m, 4H), 2.36 (s, 3H), 1.78 (t, 2H,
J ) 7.7 Hz), 1.07 (quintet, J ) 7.9 Hz); 31P{1H} NMR (CD2Cl2,
121.5 MHz): δ 79.27 (br s, 1P), 10.47 (d, 2P, J ) 2.8 Hz). Anal.
Calcd for C50H51O9P3Ir]+BF4-: 51.42% C, 4.40% H. Found:
51.17% C, 4.06% H.
a nitrogen atmosphere with [(CRdCRCRdCR)Ir (PPh3)2(Cl)]
(5; R ) CO2Me; 1.88 g, 1.8 mmol) and bis(2-diphenylphosphi-
noethyl)phenylphosphine (1.23 g, 2.3 mmol). Dry toluene (120
mL) was vacuum distilled into the flask, and the solution was
heated under nitrogen at reflux for 24 h. The reaction mixture
was cooled to room temperature and filtered to remove a pre-
cipitate which was then washed sequentially with benzene and
hexanes and dried in vacuo to give 6-fac as a pink/tan powder
(1.24 g, 65% yield). An analytically pure sample of 6-fac was
obtained by recrystallization by slow diffusion from CH2Cl2/
Et2O. mp: 289 °C (dec); IR(KBr): 1692(vs), 1486(s), 1434(s),
1
1331(s) cm-1; H NMR (CD2Cl2, 300 MHz): δ 7.76-6.67 (m,
25 H), 3.44 (m, 4H), 3.31 (s, 6H), 2.52 (s, 6H), 2.33 (m, 4H);
31P{1H} NMR (CD2Cl2, 121.5 MHz): A2B, δ(PA) ) -0.63, δ-
2
(PB) ) 56.03; J (PAPB) ) 7.1 Hz). Anal. Calcd for C46H45O8P3-
ClIr: 52.80% C, 4.33% H. Found: 52.64% C, 4.11% H.
X-r a y Str u ctu r e Deter m in a tion for [{P P h (CH2CH2-
[{P P h (CH2CH2P P h 2)2}Ir (CRdCR-CRdCR)Cl] (6-m er ,
R ) CO2CH3). The supernatant from the filtration of 6-fac
(above) was slowly evaporated in the hood yielding analytically
pure square orange crystals of 6-mer (10 mg, 5.3% yield). mp:
274-279 °C; IR(KBr): 1696(vs), 1434(s), 1333(s) cm-1; 1H NMR
(CDCl3, 300 MHz): δ 7.77-7.07 (m, 25 H), 3.76 (s, 3H), 3.50
(s, 3H), 3.31 (s, 3H), 3.19 (s, 3H), 2.85 (m, 4H), 2.55 (m, 2H);
31P{1H} NMR (CDCl3, 121.5 MHz): δ 58.27 (t, J ) 8.0 Hz),
1.6 (d, J ) 8.0 Hz). Anal. Calcd for C46H45O8P3ClIr: 52.80%
C, 4.33% H. Found: 52.56% C, 4.02% H.
P P h 2)2}Ir (CRdCRCRdCR)(dCOCH2CH2CH2)]BF 4 (9, R )
CO2CH3). Crystals of 9 were obtained by slow diffusion from
CH2Cl2/Et2O. The crystals were found to rapidly lose solvent
when removed from the mother liquor. Therefore, a satisfac-
tory crystal for diffraction studies was obtained by removal of
the crystal from the mother liquor, followed by rapid placement
in paratone, and data collection at low temperature. Data were
collected at the University of CaliforniasSan Diego X-ray
Facility with a Siemens R3m/V automated diffractometer
system with a dedicated Microvax II computer system. The
parameters used during the data collection are summarized
in the Supporting Information. All computations used the
SHELTXTL PLUS (Version 3.4) program library (Siemens
Corp., Madison, WI). The structures were solved by direct
methods and refined by full matrix-least-squares methods. All
nonhydrogen atoms were located on a series of difference
Fourier maps. Hydrogen atom positions were added in ideal
calculated positions with d(C-H) ) 0.96 Å and with fixed
isotropic thermal parameters set at 1.2 to 1.3 times the
isotropic equivalent of the attached carbon atom, with a
maximum value of U ) 0.10. Crystal data for 9: C50H51BF4-
IrO9P3, Mw) 1167.83, monclinic, C2/c, a ) 26.10(3) Å, b )
28.42(3) Å, c ) 15.19(2) Å, â ) 124.64(9), V ) 9268(21) Å3, Z
) 8, dcalcd ) 1.674 g cm-3, R1 ) 0.0664 (I > 2σ(I)), wR2 )
0.1434.
[{P P h (CH2CH2P P h 2)2}Ir (CRdCR-CRdCR)(ClCH2Cl)]-
BF 4 (7, R ) CO2CH3). A 100 mL round-bottom flask was
charged under a nitrogen atmosphere with 6-fac (628 mg, 0.60
mmol), AgBF4 (129 mg, 0.66 mmol), and dry CH2Cl2 (50 mL).
After 60 h at room temperature, the solvent was removed in
vacuo. The residue was taken up in CHCl3 (50 mL, wet) and
the solution stirred in the air for 1 h. The mixture was filtered
through Celite and concentrated in vacuo, and hexanes were
added to give 7 as a bright yellow powder (616 mg, 87% yield).
mp: 195 °C (dec); IR(KBr): 1707(vs), 1435(s), 1062 (m) cm-1
;
1H NMR (CDCl3, 300 MHz): δ 7.59-7.18 (m, 25 H), 5.47 (s,
2H), 3.89 (s, 3H), 3.55-3.78 (m, 2H), 3.47 (s, 3H), 3.34 (s, 3H),
3.18-2.86 (m, 6 H), 2.41 (s, 3H); 31P{1H} NMR (CDCl3, 121.5
MHz): δ 62.87 (t, 1P, J ) 8.4 Hz), 12.97 (br s, 2P). Anal. Calcd
for C47H47O8P3Cl2IrBF4: 47.73% C, 4.01% H. Found: 47.78%
C, 4.25% H.
Ack n ow led gm en t. Financial support by the Na-
tional Science Foundation (CHE-9970480) and a gener-
ous loan of precious metals from J ohnson Matthey are
gratefully acknowledged.
[{P P h (CH2CH2P P h 2)2}Ir (CRdCRCRdCR)(CO)]BF 4 (8,
R ) CO2CH3). Carbon monoxide gas was bubbled through a
wet CH2Cl2 (30 mL) solution of 7 (102.1 mg, 0.08 mmol) for 1
h at room temperature. The CO-saturated solution was then
stirred at room temperature for 24 h, followed by evapora-
tion of the volatiles in vacuo. The residue was dissolved in
CH2Cl2, and addition of Et2O led to precipitatation of 8 as an
off-white powder (73 mg, 75% yield). Recrystallization from
THF/MeOH/Et2O afforded 45.2 mg (46% yield) of analytically
pure white crystals. mp: 270-272 °C. IR(KBr): 2069 (s), 1702
Su p p or tin g In for m a tion Ava ila ble: Tables of crystal
data and structure refinement, atomic coordinates, bond
lengths and angles, anisotropic displacement parameters, and
hydrogen coordinates for 9. These materials are available free
of charge via the Internet at http://pubs.acs.org.
(s) 1062 (m) cm-1
.
1H NMR (CDCl3, 500 MHz): δ 7.66 (m, 4
OM000848W