Structural and chemical properties of zwitterionic iridium complexes featuring the tripodal phosphine ligand [PhB(CH2PPh2)3]-

Article abstract of DOI:10.1021/om0205086

The structural and chemical properties of zwitterionic iridium complexes featuring the tripodal phosphine ligand [PhB(CH₂PPh₂)₃]^- were investigated. Several C-H activation reactions have been observed too. The spectroscopic analysis was also carried out.

Full text of DOI:10.1021/om0205086

4050
Organometallics 2002, 21, 4050-4064
Str u ctu r a l a n d Ch em ica l P r op er ties of Zw itter ion ic
Ir id iu m Com p lexes F ea tu r in g th e Tr ip od a l P h osp h in e
Liga n d [P h B(CH2P P h 2)3]-
J ay D. Feldman, J onas C. Peters,† and T. Don Tilley*
Department of Chemistry, University of California at Berkeley,
Berkeley, California 94720-1460
Received J une 26, 2002
-
Several new iridium compounds bearing the PhB(CH2PPh2)3 (herein abbreviated as
[PhBP3]) ligand have been prepared and characterized, and a comparison of steric, electronic,
and chemical properties is made with those of related pentamethylcyclopentadienyl (Cp*)
and hydridotris(3,5-dimethylpyrazolyl)borate (TpMe ) complexes. The complexes [PhBP3]Ir-
2
(H)(η3-C8H13) (2) and [PhBP3]Ir(H)(η3-C3H5) (3) were synthesized from the reaction of [Li-
(TMED)][PhBP3] (1) with the corresponding [(alkene)2IrCl]2 complex. These allyl complexes
serve as precursors to the dihalides [PhBP3]IrX2 (10, X ) I; 12, X ) Cl). In addition to these
dihalides, the five-coordinate species [PhBP3]IrMe2 (16) and [ClB(CH2PPh2)3]IrCl2 (13) have
been isolated. Addition of CO to 2 or 3 gave [PhBP3]Ir(CO)2 (7), while reaction of H2 with 2
yielded {[PhBP3]IrH2}2 (8) in benzene and [PhBP3]Ir(COE)H2 (9) in THF (where COE )
cyclooctene). Complex 2 reacted with PMePh2 to give [PhBP3]Ir(PMePh2)H2 (5) and 1,3-
cyclooctadiene. The protonation of 5 with [H(OEt2)]{B[3,5-C6H3(CF3)2]4} gave the classical
hydride complex {[PhBP3]Ir(PMePh2)H3}{B[3,5-C6H3(CF3)2]4} (6). In addition to the formation
of allyl complexes 2 and 3, several C-H activation reactions have been observed; addition
of PMe3 to 2 provided the cyclometalated product {PhB[(CH2PPh2)2(CH2PPhC6H4)]}Ir(H)-
(PMe3) (4) and COE. Photolysis of 5 gave {PhB[(CH2PPh2)2(CH2PPhC6H4)]}Ir(H)(PMePh2)
(A) and [PhBP3]Ir(H)(PMePhC6H4) (B). Complex 9 catalyzes H/D exchange between COE
and benzene-d6. Metathesis reactions of diiodide 10 with LiBHEt3 gave [Li(THF)n]{[PhBP3]-
Ir(H)2I} (14a ) and [Li(THF)n]{[PhBP3]Ir(H)3} (15). Comparison of the spectroscopic properties
of related [PhBP3]Ir, Cp*Ir, and TpMe Ir complexes suggests that relative donating abilities
2
follow the trend [PhBP3] g Cp* > TpMe , and structural comparisons indicate that [PhBP3]
2
is the most sterically demanding ligand.
In tr od u ction
Recent reports have described a new type of anionic
six-electron ligand based on phosphorus donors, PhB-
Advances in transition-metal chemistry are to a large
extent paced by the design and synthesis of new types
of ligands which influence the properties and reactivity
of a metal center. Currently, there is significant interest
in anionic six-electron donors such as cyclopentadienyl
(Cp), pentamethylcyclopentadienyl (Cp*), hydridotris-
(pyrazolyl)borate (Tp), and hydridotris(3,5-dimethylpyra-
(CH2PPh2)3 (herein abbreviated as [PhBP3]).9,10 Re-
-
lated sulfur-based ligands, PhB(CH2SR)3-, have been
developed by Riordan and co-workers.11 In some ways,
[PhBP3] would seem to possess properties that are
intermediate between those of Tp ligands and Cp
ligands. For [PhBP3] the phosphorus donor atoms are
soft, like the π-system of Cp ligands, yet [PhBP3]
zolyl)borate (TpMe ). Transition-metal complexes featur-
2
(3) Tellers, D. M.; Bergman, R. G. J . Am. Chem. Soc. 2000, 122,
954-955.
ing these ligands are common in organometallic chem-
istry and exhibit a rich variety of interesting catalytic
and stoichiometric reactions. Despite the isoelectronic
relationship between these ligands, they differ signifi-
cantly; for example, Cp* is a relatively soft ligand which
(4) Tellers, D. M.; Bergman, R. G. Organometallics 2001, 20, 4819-
4832.
(5) Kitajima, N.; Tolman, W. B. Prog. Inorg. Chem. 1995, 43, 419-
531.
(6) Koch, J . L.; Shapley, P. A. Organometallics 1997, 16, 4071-4076.
(7) Gutierrez-Puebla, E.; Monge, A.; Nicasio, M. C.; Perez, P. J .;
Poveda, M. L.; Rey, L.; Ruiz, C.; Carmona, E. Inorg. Chem. 1998, 37,
4538-4546.
coordinates with its π-system, while TpMe has relatively
2
hard nitrogen σ-donors.1 Such factors are likely respon-
(8) Gutierrez-Puebla, E.; Monge, A.; Paneque, M.; Poveda, M. L.;
Taboada, S.; Trujillo, M.; Carmona, E. J . Am. Chem. Soc. 1999, 121,
346-354.
sible for the differences in properties and reactivities
observed for analogous TpMe and Cp* complexes.1-8
2
(9) Barney, A. A.; Heyduk, A. F.; Nocera, D. G. Chem. Commun.
1999, 2379-2380.
† Current address: Division of Chemistry and Chemical Engineer-
ing, California Institute of Technology, Pasadena, CA 91125.
(1) Trofimenko, S. Chem. Rev. 1993, 93, 943-980.
(2) Tellers, D. M.; Skoog, S. J .; Bergman, R. G.; Gunnoe, T. B.;
Harman, W. D. Organometallics 2000, 19, 2428-2432.
(10) Peters, J . C.; Feldman, J . D.; Tilley, T. D. J . Am. Chem. Soc.
1999, 121, 9871-9872.
(11) Schebler, P. J .; Riordan, C. G.; Guzei, I. A.; Rheingold, A. L.
Inorg. Chem. 1998, 37, 4754-4755.
10.1021/om0205086 CCC: $22.00 © 2002 American Chemical Society
Publication on Web 08/31/2002

Zwitterionic Iridium Complexes
Organometallics, Vol. 21, No. 20, 2002 4051
Sch em e 1
coordinates with three σ-donor atoms, as do Tp ligands.
In a previous communication, a zwitterionic iridium
complex featuring this ligand was shown to display a
previously unknown reaction type in the extrusion of
dimesitylsilylene from dimesitylsilane to give [PhBP3]-
(H)2IrdSiMes2 (Mes ) 2,4,6-trimethylphenyl).10 This
contribution describes the synthesis and reactivity of
several new iridium complexes featuring this ligand. A
comparison of the reactivity and properties of [PhBP3]-
The 11B NMR shift for 1 (δ -14.0), as well as various
iridium complexes prepared herein, is consistent with
- 21
a four-coordinate borate of the type BR4
.
Phosphine 1 undergoes salt metathesis with [(COE)2-
IrCl]2 (COE ) cyclooctene) to give zwitterionic [PhBP3]-
Ir(H)(η3-C8H13) (2) via C-H activation of a COE ligand.
Isolation of pure, colorless 2 from the greenish brown
product mixture was difficult, due to the similar solu-
bilities of the desired product and impurities. However,
analytically pure 2 was obtained in 65-87% yield via
multiple crystallizations from toluene. The 31P{1H}
Ir to those of analogous Cp*Ir and TpMe Ir fragments
2
indicates that the [PhBP3] ligand is strongly electron-
donating toward iridium and is quite sterically demand-
ing. Many studies have focused on the ability of com-
NMR spectrum of 2 contains a doublet (δ -7.77, 2J PP
)
2
22 Hz) and a triplet (δ -13.37, J PP ) 22 Hz) in a 2:1
ratio, consistent with a mirror plane of symmetry that
bisects the [PhBP3] ligand. Diagnostic features of the
1H NMR spectrum include the allyl methine resonances
(multiplets at δ 4.90 and 3.57) and an iridium hydride
resonance (δ -12.55), which appears as a doublet of
triplets due to large trans-phosphine coupling (2J HP(trans)
) 150 Hz) and significantly weaker coupling to the cis-
phosphines (2J HP(cis) ) 14 Hz). These NMR data are
consistent with the structure for 2 shown in Scheme 1.
This transformation is analogous to that used to prepare
TpIr(H)(COE)(η1-C8H13) and TpIr(H)(η3-C8H13) from
KTp and [(COE)2IrCl]2.22-24
plexes derived from Cp*Ir or TpMe Ir to activate C-H
2
bonds.12-20 As described here, C-H activations also
occur readily in [PhBP3]Ir complexes.
Resu lts
P r ep a r a tion of [P h BP 3]Ir Allyl Com p lexes. [Li-
(TMED)][PhBP3] (1; TMED ) N,N,N′,N′-tetramethyl-
ethylenediamine) was readily prepared via the low-
temperature addition of dichlorophenylborane to [Li-
(TMED)][CH2PPh2] (3 equiv) in 72% yield as a colorless,
crystalline solid (Scheme 1). The 31P{1H} NMR spect-
trum of 1 contains a single resonance at δ -12.4 for the
equivalent phosphines, and 1H NMR spectroscopy re-
veals that 1 equiv of TMED is retained in the product.
The allyl hydride complex [PhBP3]Ir(H)(η3-C3H5) (3)
was obtained by addition of 1 to a THF solution of
[(COE)2IrCl]2 that had been saturated with propene. No
dark impurities were observed, unlike in the prepara-
tion of 2; the color of the solution remained yellow
throughout the reaction time of 24 h. Compound 3 was
therefore easier to isolate and purify, and it was
obtained in 72% yield after crystallization from THF.
The 31P{1H} and 1H NMR spectra of 3 are similar to
(12) For examples, see refs 4 and 13-20.
(13) Slugovc, C.; Padilla-Martinez, I.; Sirol, S.; Carmona, E. Coord.
Chem. Rev. 2001, 213, 129-157.
(14) Slugovc, C.; Mereiter, K.; Trofimenko, S.; Carmona, E. Angew.
Chem., Int. Ed. 2000, 39, 2158-2160.
(15) Gutierrez-Puebla, E.; Monge, A.; Nicasio, M. C.; Perez, P. J .;
Poveda, M. L.; Carmona, E. Chem. Eur. J . 1998, 4, 2225-2236.
(16) Ghosh, C. K.; Hoyano, J . K.; Krentz, R.; Graham, W. A. G. J .
Am. Chem. Soc. 1989, 111, 5480-5481.
(21) Kidd, R. G. NMR of Newly Accessible Nuclei; Academic Press:
New York, 1983; Vol. 2.
(17) Rest, A. J .; Whitwell, I.; Graham, W. A. G.; Hoyano, J . K.;
McMaster, A. D. J . Chem. Soc., Dalton Trans. 1987, 1181-1190.
(18) Asbury, J . B.; Hang, K.; Yeston, J . S.; Cordaro, J . G.; Bergman,
R. G.; Lian, T. Q. J . Am. Chem. Soc. 2000, 122, 12870-12871.
(19) J anowicz, A. H.; Bergman, R. G. J . Am. Chem. Soc. 1983, 105,
3929-3939.
(22) Fernandez, M. J .; Rodriguez, M. J .; Oro, L. A.; Lahoz, F. J . J .
Chem. Soc., Dalton Trans. 1989, 2073-2076.
(23) Alvarado, Y.; Boutry, O.; Gutierrez, E.; Monge, A.; Nicasio, M.
C.; Poveda, M. L.; Perez, P. J .; Ruiz, C.; Bianchini, C.; Carmona, E.
Chem., Eur. J . 1997, 3, 860-873.
(20) Tellers, D. M.; Yung, C. M.; Arndtsen, B. A.; Adamson, D. R.;
Bergman, R. G. J . Am. Chem. Soc. 2002, 124, 1400-1410.
(24) Tanke, R. S.; Crabtree, R. H. Inorg. Chem. 1989, 28, 3444-
3447.

4052 Organometallics, Vol. 21, No. 20, 2002
Ta ble 1. Cr ysta llogr a p h ic Da ta for Com p ou n d s 2-4 a n d 8
Feldman et al.
2‚THF
3‚C6H6
4‚CH2Cl2‚C5H12
8‚C6H6
empirical formula
C57H62BP3IrO
1059.07
yellow, plate
0.18 × 0.16 × 0.02
triclinic
C54H53BP3Ir
997.99
C54H64BP4IrCl2
1110.98
C51H49BP3Ir
fw
957.93
cryst color, habit
colorless, prism
0.32 × 0.30 × 0.15
monoclinic
P21/n (No. 14)
11.2342(2)
17.0483(3)
23.6861(5)
90
colorless, block
0.22 × 0.14 × 0.13
monoclinic
P21/n (No. 14)
11.5654(2)
22.8776(2)
18.5238(2)
90
orange, block
0.27 × 0.05 × 0.02
triclinic
cryst size (mm)
cryst syst
space group
P1h (No. 2)
12.2337(7)
13.2280(8)
16.7505(10)
92.164(1)
108.453(1)
111.029(1)
2364.7(2)
4471, 3.0-46.0
2
P1h (No. 2)
12.446(2)
13.005(2)
14.348(2)
91.562(3)
100.118(3)
113.984(3)
2081.4(5)
992, 3.0-46.0
4
a (Å)
b (Å)
c (Å)
R (deg)
â (deg)
101.833(1)
90
98.72(1)
90
γ (deg)
V (Å3)
4440.1(1)
8192, 3.0-46.0
4
4844.5(1)
8192, 3.0-46.0
4
orientation rflns: no., 2θ range (deg)
Z
Dcalcd (g/cm3)
1.487
1.394
1.405
1.468
F000
1078.00
1872.00
2056.00
924.00
µ(Mo KR) (cm-1
diffractometer
radiation
)
29.73
31.55
30.36
33.64
SMART
Mo KR (λ ) 0.710 69 Å), graphite monochromated
temp (K)
scan type
155(1)
154(1)
150(1)
ω (0.3° per frame)
10.0
147(1)
scan rate (s/frame)
data collected, 2θmax (deg)
no. of rflns measd
total
unique
Rint
51.9
51.3
49.4
51.3
13 046
7957
0.049
22 162
9110
0.048
24 354
8219
0.067
10 644
6717
0.037
transmissn factors
Tmax
0.93
0.57
0.69
0.54
0.65
0.95
0.61
Tmin
0.34
structure soln
direct methods (SIR92)
no. of obsd data (I > 3σ(I))
no. of params refined
rfln/param ratio
final residuals: R; Rw; Rall
goodness-of-fit indicatorb
max shift/error final cycle
5074
259
19.59
0.045; 0.043; 0.087
1.13
0.01
1.20, -0.91
4968
527
9.43
0.028; 0.032; 0.063
1.19
0.00
4898
543
9.02
0.035; 0.037; 0.069
0.99
0.04
2102
278
7.56
0.050; 0.050; 0.106
1.02
0.00
a
max, min peaks, final diff map (e/Å3)
1.97, -1.11
1.34, -1.85
1.81, -1.24
a
2 1/2 b
R ) ∑||Fo| - |Fc||/∑|Fo|; Rw ) [∑w(|Fo| - |Fc|)2/∑wFo
]
.
Goodness of fit ) [∑w(|Fo| - |Fc|)2/(Nobservns - Nparams)]1/2
.
F igu r e 1. ORTEP diagram of [PhBP3]Ir(η3-C8H13)H (2).
F igu r e 2. ORTEP diagram of [PhBP3]Ir(η3-C3H5)H (3).
those of 2 and are consistent with its characterization
as an η3-allyl hydride complex.
Ta ble 2. Selected Bon d Dista n ces (Å) a n d An gles
(d eg) for 2
The solid-state structures of 2 and 3 (Figures 1 and
2, respectively) were determined by single-crystal X-ray
diffraction; selected bond distances and angles are listed
in Tables 2 and 3. The expected facial coordination of
the tripodal phosphine ligand in both cases is reflected
in P-Ir-P angles of approximately 90° (88-90° for 2;
87-91° for 3). The C-Ir bond distances for the η3-allyl
ligands range from 2.18 to 2.30 Å for 2 and from 2.19
to 2.26 Å for 3. These distances are similar to those
found in other Ir(III) allyl complexes, which are on
average 2.24 Å.23,25-33 The position of the hydride ligand
was not determined for either 2 or 3; however, its
(a) Bond Distances
Ir1-P1
Ir1-P2
Ir1-P3
Ir1-C1
2.409(2)
2.304(2)
2.311(2)
2.302(9)
Ir1-C2
Ir1-C3
C1-C2
C2-C3
2.176(8)
2.261(9)
1.43(1)
1.43(1)
(b) Bond Angles
P1-Ir1-P2
P1-Ir1-P3
P2-Ir1-P3
87.96(8)
90.31(8)
90.11(8)
C1-C2-C3
C2-C1-C8
C2-C3-C4
120.9(8)
123.0(8)
124.0(7)
approximate location is indicated by the open coordina-
tion site trans to P(1). The greater trans influence of
the hydride relative to the η3-allyl ligand is reflected in

Zwitterionic Iridium Complexes
Organometallics, Vol. 21, No. 20, 2002 4053
Ta ble 3. Selected Bon d Dista n ces (Å) a n d An gles
(d eg) for 3
(a) Bond Distances
Ir-P1
Ir-P2
Ir-P3
Ir-C1
2.388(2)
2.320(1)
2.307(2)
2.255(6)
Ir-C2
Ir-C3
C1-C2
C2-C3
2.186(6)
2.234(6)
1.405(9)
1.402(9)
(b) Bond Angles
P1-Ir-P2
P1-Ir-P3
91.05(5)
89.69(6)
P2-Ir-P3
C1-C2-C3
87.47(6)
121.9(6)
the elongated Ir-P(1) distance of 2.408(2) Å, which may
be compared to the Ir-P(2) and Ir-P(3) distances of
2.304(2) and 2.311(2) Å, respectively, for 2 (2.388(2) vs
2.320(1) and 2.307(2) Å for 3).
Rea ction s of [P h BP 3]Ir Allyl Com p lexes w ith
P h osp h in es. Reaction of 2 with PMe3 (1.4 equiv, room
temperature, 3 h) in benzene-d6 resulted in intramo-
lecular metalation to give 4 (eq 1) with the concomitant
formation of COE. 31P{1H} NMR spectroscopy indicates
F igu r e 3. ORTEP diagram of {PhB[(CH2PPh2)2(CH2-
PPhC6H4)]}Ir(H)(PMe3) (4), in which one of the phenyl
groups on P1 has been omitted for clarity.
Ta ble 4. Selected Bon d Dista n ces (Å) a n d An gles
(d eg) for 4
(a) Bond Distances
Ir-P1
Ir-P2
Ir-P3
2.377(2)
2.320(2)
2.377(2)
Ir-P4
Ir-C1
C1-C6
2.325(2)
2.116(7)
1.40(1)
(b) Bond Angles
P1-Ir-P2
P1-Ir-P3
P1-Ir-P4
P2-Ir-P3
P2-Ir-P4
91.22(6)
88.41(7)
105.84(7)
90.51(6)
155.28(7)
P3-Ir-P4
C1-Ir-P1
C1-Ir-P2
C1-Ir-P3
C1-Ir-P4
107.39(7)
90.2(2)
67.6(2)
158.1(2)
94.0(2)
crystallization from CH2Cl2, pure 4‚2CH2Cl2 was iso-
lated in 92% yield.
quantitative formation of a product with four inequiva-
lent phosphorus atoms. Two of these P atoms are trans
to one another (δ -59.22, -72.67, J PP(trans) ) 282 Hz),
The structure of 4 was confirmed by X-ray crystal-
lography; an ORTEP diagram is depicted in Figure 3,
and selected bond distances and angles are given in
Table 4. The facially coordinating [PhBP3] ligand gives
rise to P-Ir-P angles ranging from 88 to 91°, but the
remaining iridium-ligand bonds reflect substantial
distortions from ideal octahedral geometry. The four-
membered IrPC2 ring confines the geometry of this
complex, resulting in C(1)-Ir-P angles of 67.6(2), 90.2-
(2), 94.0(2), and 158.1(2)°. Likewise, the PMe3 ligand is
tilted away from the two bulky phosphine ligands (P(4)-
Ir-P(1) and P(4)-Ir-P(3) angles of 105.84(7) and
107.39(7)°, respectively), giving rise to a P(4)-Ir-P(2)
angle of 155.28(7)°. The hydride ligand was not located
by X-ray diffraction, but its position is assumed to be
in the otherwise open coordination site trans to P(1).
Overall, the structure of 4 is similar to that of the
2
and two are cis to three other phosphines (δ -1.87,
-17.55, 2J PP(cis) ) 18 Hz). Also, 1 equiv of free COE and
an iridium hydride resonance (δ -9.32, 2J HP(trans) ) 121
1
Hz) are observed in the H NMR spectrum. These data
suggest a product derived from intramolecular C-H
activation of one of the P-Ph groups to give the ortho-
metalated complex {PhB[(CH2PPh2)2(CH2PPhC6H4)]}Ir-
(H)(PMe3) (4). Formation of the four-membered ring in
complex 4 may be irreversible, as prolonged thermolysis
of 4 in benzene-d6 (85 °C, 1 week) failed to produce any
new products resulting from C-D activation (by 31P-
{1H} and 1H NMR spectroscopy). Upon scale-up and
(25) Hsu, R. H.; Chen, J . T.; Lee, G. H.; Wang, Y. Organometallics
1997, 16, 1159-1166.
(26) Schnabel, R. C.; Roddick, D. M. Organometallics 1996, 15,
3550-3555.
related complex cis-(Ph3P)2(Ph2PC6H4)Ir(H)(Br).34
A dissimilar reaction occurred upon thermolysis of 2
in the presence of PMePh2 (80 °C, benzene, 24 h). In
this case the allyl complex was observed to undergo â-H
elimination to give 1,3-cyclooctadiene (1,3-COD, by GC/
MS and 1H NMR spectroscopy), and the coordination
of PMePh2 to iridium gave [PhBP3]Ir(PMePh2)H2 (5; eq
2) in 46% isolated yield. Complex 5 has Cs symmetry,
(27) Wakefield, J . B.; Stryker, J . M. Organometallics 1990, 9, 2428-
2430.
(28) Merola, J . S. Organometallics 1989, 8, 2975-2977.
(29) McGhee, W. D.; Hollander, F. J .; Bergman, R. G. J . Am. Chem.
Soc. 1988, 110, 8428-8443.
(30) McGhee, W. D.; Bergman, R. G. J . Am. Chem. Soc. 1986, 108,
5621-5622.
(31) Tulip, T. H.; Ibers, J . A. J . Am. Chem. Soc. 1979, 101, 4201-
4211.
(32) Schoonover, M. W.; Baker, E. C.; Eisenberg, R. J . Am. Chem.
Soc. 1979, 101, 1880-1882.
(33) Kaduk, J . A.; Poulos, A. T.; Ibers, J . A. J . Organomet. Chem.
1977, 127, 245-260.
(34) Vondeuten, K.; Dahlenburg, L. Cryst. Struct. Commun. 1980,
9, 421-427.

4054 Organometallics, Vol. 21, No. 20, 2002
Feldman et al.
2
-11.21 for the hydride ligands (dm, J HP ) 112 Hz) by
1H NMR spectroscopy. The T1(min) value for this
resonance was determined to be 281 ( 5 ms (-18 °C,
CD2Cl2, 500 MHz), while that of the IrH resonance for
5 is 274 ( 5 ms (-28 °C, CD2Cl2, 500 MHz). Both T1-
(min) values are well within the range expected for
classical hydride complexes.40,41
P r ep a r a tion of [P h BP 3]Ir (CO)2. The preparation
of carbonyl complexes of the [PhBP3]Ir fragment was
of interest, since the ν(CO) stretching frequencies of
such species should provide information regarding the
electronic properties of the [PhBP3] ligand. Complexes
2 and 3 reacted with carbon monoxide (1 atm, 80 °C,
benzene) over several days to give cyclooctene and
propene, respectively, and an iridium-containing prod-
uct (7) that exhibits a single 31P{1H} NMR resonance
at δ -10.6. When 13CO was employed in the synthesis
of 7, this 31P NMR resonance appeared as a triplet (2J PC
) 24 Hz), indicating the coordination of two carbonyl
ligands to give the 18-electron Ir(I) species [PhBP3]Ir-
(CO)2, as shown in eq 4. The IR spectrum of 7 in hexanes
with a mirror plane that contains the iridium center,
the phosphorus donor of the PMePh2 ligand, and one of
the phosphine donors of the [PhBP3] ligand. The equiva-
lent hydride ligands give rise to a 1H NMR resonance
at δ -11.04 (dm, 2J HP(trans) ) 107 Hz). The 31P{1H} NMR
spectrum of 5 displays an A2MX pattern; two of the
[PhBP3] phosphorus atoms are equivalent and trans to
2
hydride ligands (δ -10.42, t, J PP(cis) ) 21 Hz), and the
third [PhBP3] phosphorus atom and PMePh2 are trans
to one another (δ -0.98 and -16.84, respectively;
2J PP(trans) ) 285 Hz).
Rea ction s of [P h BP 3]Ir (P MeP h 2)H2 (5). Photolysis
of 5 (benzene-d6, 13 h) resulted in elimination of H2, and
intramolecular C-H activation occurred exclusively (no
C-D activation of benzene-d6 by NMR spectroscopy).
A mixture of two products was observed, and on the
basis of spectroscopic properites we propose that these
are derived from ortho metalation of the [PhBP3] and
PMePh2 phenyl groups (A and B in eq 3). Like meta-
contains CO stretching frequencies of 2024 and 1940
cm-1
.
Rea ction s of th e Allyl Com p lexes w ith H2. Heat-
ing a benzene solution of 2 under 1 atm of H2 (80 °C, 19
h) produced COE (by 1H NMR spectroscopy) and an
orange crystalline compound (8; Scheme 2). The hydro-
genation of 3 (benzene-d6, 80 °C, 48 h) also yielded
polyhydride 8, as well as propane (by 1H NMR spec-
troscopy). Complex 8 is insoluble in a wide range of
solvents (benzene, THF, CH2Cl2, C6H5F, DMSO, DMF,
dioxane) and was therefore characterized by IR spec-
troscopy, X-ray crystallography, and elemental analysis
(but not NMR spectroscopy).
Sch em e 2
lation product 4, A and B exhibit A2MX patterns in their
31P{1H} NMR spectra. The ratio of A to B is 2:5,
indicating that C-H activation of the eight P-phenyl
substituents is nearly statistical (2:6).
A variety of Tp′Ir(PR3)H2 and Cp′Ir(PR3)H2 complexes
(where Tp′ is Tp or TpMe and Cp′ is Cp or Cp*) are
2
known to undergo protonation to give cationic hydrides.
+
While Cp′Ir(PR3)H3 complexes are classical hydrides,
as determined by neutron diffraction studies,35-37 Tp′Ir-
(PR3)(H2)(H)+ derivatives adopt nonclassical structures,
1
as determined by T1(min) H NMR data.38
Protonation of 5 with [H(OEt2)2]{B[3,5-C6H3(CF3)2]4}39
gave the new cationic hydride {[PhBP3]Ir(PMePh2)H3}-
{B[3,5-C6H3(CF3)2]4} (6), which exhibits a shift of δ
An X-ray diffraction study revealed a dimeric struc-
ture for 8 (Figure 4; selected bond distances and angles
(38) Oldham, W. J .; Hinkle, A. S.; Heinekey, D. M. J . Am. Chem.
Soc. 1997, 119, 11028-11036.
(35) Zilm, K. W.; Heinekey, D. M.; Millar, J . M.; Payne, N. G.;
Neshyba, S. P.; Duchamp, J . C.; Szczyrba, J . J . Am. Chem. Soc. 1990,
112, 920-929.
(36) Heinekey, D. M.; Millar, J . M.; Koetzle, T. F.; Payne, N. G.;
Zilm, K. W. J . Am. Chem. Soc. 1990, 112, 909-919.
(37) Heinekey, D. M.; Hinkle, A. S.; Close, J . D. J . Am. Chem. Soc.
1996, 118, 5353-5361.
(39) Brookhart, M.; Grant, B.; Volpe, A. F. Organometallics 1992,
11, 3920-3922.
(40) Crabtree, R. H.; Lavin, M.; Bonneviot, L. J . Am. Chem. Soc.
1986, 108, 4032-4037.
(41) Crabtree, R. H.; Hamilton, D. G. J . Am. Chem. Soc. 1986, 108,
3124-3125.

Zwitterionic Iridium Complexes
Organometallics, Vol. 21, No. 20, 2002 4055
H)]2[BPh4]2 (triphos ) MeC(CH2PPh2)3), has been pre-
pared by Bianchini and co-workers.47
The IR spectrum (KBr) of 8 features an absorption
at 2114 cm-1, which we attribute to the terminal Ir-H
stretch. Although the bridging Ir-H stretch could not
be identified with certainty, a peak observed at 1088
cm-1 is consistent with literature values for related
species.46,48,49 To confirm these assignments, we at-
tempted to label the hydride ligands by carrying out the
reaction of 3 with D2 in benzene-d6 (73 °C, 15 h). This
led to formation of an orange solid and a ca. 1:1 mixture
of COE and COE-d14 (by H and H{1H} NMR spectros-
copy and GC/MS). An IR spectrum of the solid suggests
that the hydride positions of 8 are only partially
deuterated. Although the peak assigned to the terminal
Ir-H stretch (2114 cm-1) of 8 is present, it has a
reduced intensity relative to the other peaks in the
spectrum. Furthermore, a new peak at 1514 cm-1 is
present, which may be attributed to a terminal Ir-D
stretch. Scrambling of the ortho hydrogens of the PPh2
substituent with the iridium hydride positions could
account for the formation of a mixture of 8 and 8-dx.
We have observed a related scrambling process in which
deuterium is incorporated into the ortho hydrogen
positions of the [PhBP3] ligand in reactions of 2 with
Mes2SiD250 and have characterized an ortho-metalated
product of this ligand (4; vide supra).
To determine the exact formula for dimer 8, we
attempted to independently generate the two possible
structures, {[PhBP3]Ir(H)x(µ-H)}2, where x ) 1, 2.
Toward this end we discovered that [PhBP3]Ir(COE)H2
(9) could be prepared by the hydrogenation of 3 in THF
(rather than in benzene). This reaction also produces
the insoluble dimer 8 as a side product (by IR spectros-
copy). The yield of 9 (59%) was optimized by performing
the hydrogenation (1 atm, room temperature, 11.5 h)
in the presence of excess COE. It was anticipated that
isolated 9 could serve as a precursor to {[PhBP3]Ir(H)-
(µ-H)}2, because it contains two hydride ligands and a
potential leaving group (COE). Indeed, thermolysis of
9 (THF-d8, 80 °C, 4 h) resulted in quantitative formation
of 8 (by IR spectroscopy) and COE. Therefore, mass
balance dictates that 8 must be the dihydride dimer
{[PhBP3]Ir(H)(µ-H)}2. Its formation presumably comes
about via dissociation of COE from 9 to give [PhBP3]-
Ir(H)2, which then irreversibly dimerizes (Scheme 2).
Two additional decomposition pathways for 9 have
been observed. Thermolysis of 9 in benzene-d6 (85 °C,
2 h) instead of THF-d8 gave 8 and COE-d14 (presumably
via activation of the solvent; see Discussion). Also,
photolysis of 9 (benzene-d6, 5 h) gave 8 and COE
(undeuterated) and a small amount of H2 and allyl 2
(<10%, by NMR spectroscopy).
1
2
F igu r e 4. ORTEP diagram of {[PhBP3]Ir(H)(µ-H)}2 (8).
Ta ble 5. CO Str etch in g F r equ en cies for LIr (CO)2
Com p lexes in Hexa n es
complex
ν(CO), cm-1
TpMe Ir(CO)2
2039, 1960
2020, 1953
2024, 1940
2
Cp*Ir(CO)2
[PhBP3]Ir(CO)2
Ta ble 6. Selected Bon d Dista n ces (Å) a n d An gles
(d eg) for 8
(a) Bond Distances
Ir-P1
Ir-P2
2.298(6)
2.415(6
Ir-P3
Ir-Ir*
2.309(6)
2.796(2)
(b) Bond Angles
P1-Ir-P2
P1-Ir-P3
P2-Ir-P3
89.5(2)
84.1(2)
90.5(2)
P1-Ir-Ir*
P2-Ir-Ir*
P3-Ir-Ir*
137.3(1)
98.2(1)
137.3(2)
are given in Table 6), in which the halves of the molecule
are related by a crystallographic inversion center. Very
few diiridium complexes containing only hydrides as
bridging ligands have been structurally characterized.
The four such structures in the Cambridge Structural
Database (CSD) have Ir-Ir distances ranging from 2.46
to 2.98 Å and include [(Cp*Ir)2(µ2-H)3][ClO4],42 {[Cp*-
(PMe3)(H)Ir]2(µ2-H)}2[PF6],43 {[(Ph2PCH2CH2PPh2)Ir-
(H)]2(µ2-H)3}[BF4],44 and [{(C2F6)2PCH2CH2P(C2F6)2}(H)2-
Ir(µ2-H)]2.45 In 8, the Ir-Ir distance of 2.797(2) Å is
somewhat longer than the average distance of the
previously reported structures (2.62 Å). The tridentate
phosphine ligand is unsymmetrically coordinated with
respect to the Ir-Ir bond axis, resulting in P-Ir-Ir
angles of 137.3(1), 98.2(1), and 137.3(1)°. Although the
hydride ligands were not located in the structure
refinement, the positions of the terminal hydrides are
indicated by the open coordination sites arising from the
tilt of the triphosphine ligand (see Figure 4).
The X-ray structure suggests a di- or trihydride dimer
of the type {[PhBP3]Ir(H)x(µ-H)}2, where x ) 1, 2. For
the case where x ) 2, {[PhBP3]Ir(H)2(µ-H)}2 has two
terminal hydrides and an iridium-iridium single bond
and contains (formally) Ir(IV) centers. A similar com-
plex, [Cp*Ir(H)2(µ-H)]2, has been reported by Bergman
and co-workers.46 A rhodium compound related to the
latter hydride complex where x ) 1, [(triphos)RhH(µ-
P r ep a r a tion of [P h BP 3]Ir X2 (X ) I, Cl) Com -
p lexes. Attempts to obtain simple dihalide complexes
of the type [PhBP3]IrX2 were based on the assumption
that such species could serve as useful starting materi-
als for elaboration of the chemistry of the [PhBP3]Ir
(42) Stevens, R. C.; McLean, M. R.; Wen, T.; Carpenter, J . D.; Bau,
R.; Koetzle, T. F. Inorg. Chim. Acta 1989, 161, 223-231.
(43) Burns, C. J .; Rutherford, N. M.; Berg, D. J . Acta Crystallogr.,
Sect. C: Cryst. Struct. Commun. 1987, 43, 229-231.
(44) Wang, H. H.; Pignolet, L. H. Inorg. Chem. 1980, 19, 1470-1480.
(45) Schnabel, R. C.; Carroll, P. S.; Roddick, D. M. Organometallics
1996, 15, 655-662.
(47) Bianchini, C.; Meli, A.; Laschi, F.; Ramirez, J . A.; Zanello, P.;
Vacca, A. Inorg. Chem. 1988, 27, 4429-4435.
(48) Gill, D. S.; Maitlis, P. M. J . Organomet. Chem. 1975, 87, 359-
364.
(49) White, C.; Oliver, A. J .; Maitlis, P. M. J . Chem. Soc., Dalton
Trans. 1973, 1901-1907.
(50) Feldman, J . D.; Peters, J . C.; Tilley, T. D. Organometallics, in
press.
(46) Gilbert, T. M.; Hollander, F. J .; Bergman, R. G. J . Am. Chem.
Soc. 1985, 107, 3508-3516.

4056 Organometallics, Vol. 21, No. 20, 2002
Feldman et al.
fragment. A blood red solution of [PhBP3]IrI2 (10) was
formed upon addition of a benzene solution of I2 to a
benzene/acetonitrile (3:2) solution of 2 (eq 5). The
F igu r e 5. ORTEP diagram of [PhBP3]IrI2 (10).
diiodide 10 was isolated in 94% yield as maroon-purple
crystals after solvent removal and washing with pen-
tane. The dichloride 11 was prepared by heating a
benzene/CCl4 (1:1) solution of 2 (or 3) at 65-70 °C for 1
week, over which time a significant amount of orange
11 crystallized from solution (eq 6). The remaining
F igu r e 6. ORTEP diagram of [ClB(CH2PPh2)3]IrCl2 (13).
angles for 10 and 13 are listed in Tables 8 and 9,
respectively. Both complexes exhibit a pseudo-trigonal-
bipyramidal geometry with one halide in the axial
position (I(2)-Ir-P angles of 173.40(7), 98.34(7), and
91.99(7)° for 10 and Cl(2)-Ir-P angles of 171.8(3), 93.4-
(2), and 96.5(3)° for 13) and the other halide in the basal
plane (I(1)-Ir-P angles of 88.83(7), 134.74(7), and
137.20(7)° for 10 and Cl(1)-Ir-P angles of 88.2(2),
137.1(3), and 137.5(3)° for 13). The P-Ir-P angles in
both complexes are approximately 90°.
product was isolated in 97% yield upon solvent removal
and washing with pentane.
Clean formation of 10 from 2 and I2 was not observed
unless a mixture of benzene and acetonitrile (3:2) was
used as the solvent. NMR spectroscopy suggests that
the presence of excess acetonitrile leads to formation of
[PhBP3]Ir(η2-COE)(NCMe) (12). The 1H NMR spectrum
of 12 features an iridium-coordinated alkene resonance
at δ 2.61 (vs δ 5.65 for free COE), and the 31P{1H} NMR
spectrum reveals a complex with Cs symmetry consist-
ing of a triplet and a doublet in a 2:1 ratio (δ -8.36,
-15.69, J PP(cis) ) 23 Hz). The acetonitrile-promoted C-H
reductive elimination to form this cyclooctene complex
is reversible, and removal of the solvent under reduced
pressure resulted in complete conversion of the equi-
librium mixture to 2.
When the reaction of 2 with benzene/CCl4 (1:1) was
carried out at temperatures greater than 90 °C, a
byproduct containing a B-Cl bond was observed. This
species, [ClB(CH2PPh2)3]IrCl2 (13; eq 6), was isolated
as orange crystals in 24% yield upon thermolysis of 3
in benzene/CCl4 (1:1) at 125 °C for 10 days.
For 10, 11, and 13, only a single 31P NMR resonance
is observed in toluene-d8 over the temperature range
of 23 to -94 °C (δ 4.34, 4.92, and 0.93, respectively). A
dimeric structure of the type {[PhBP3]Ir(X)(µ-X)}2 would
give rise to two coupled resonances (AB2 spin system),
as would a monomeric trigonal-bipyramidal structure.
This implies that these molecules are fluxional in
solution.
Rea ction s of th e Dih a lid es 10 a n d 11. Initial
studies indicate that the dihalide complexes 10 and 11
are useful starting materials for metathesis reactions.
Two equivalents of LiBHEt3 (1 M in THF) reacted with
10 or 11 (in benzene-d6) to give [Li(THF)n]{[PhBP3]Ir-
(H)2X}, where X ) I (14a ), Cl (14b), as shown in Scheme
1
3. While formation of 14a is quantitative (by H NMR
spectroscopy), the addition of 2 equiv of LiBHEt3 to 11
gives a mixture of hydride complexes, including 14b (ca.
70%) as well as the trihydride [Li(THF)n]{[PhBP3]IrH3}
(15; ca. 20%). Complex 15 is formed exclusively with
the addition of 3 equiv of LiBHEt3 to 10 or 11. In each
Single-crystal X-ray diffraction studies of 10 and 13
show that these species are monomeric in the solid state.
ORTEP diagrams of 10 and 13 are displayed in Figures
5 and 6, respectively, and selected bond distances and

Zwitterionic Iridium Complexes
Organometallics, Vol. 21, No. 20, 2002 4057
Ta ble 7. Cr ysta llogr a p h ic Da ta for Com p ou n d s 10, 13, a n d 16
10‚2C7H8
13
16‚C6H6
empirical formula
fw
C59H57BP3IrI2
1315.90
C45H41BP3IrCl3
984.16
C60H58BIrP3
1074.30
cryst color, habit
cryst size (mm)
crystal syst
space group
a (Å)
b (Å)
c (Å)
purple-red, block
0.18 × 0.11 × 0.02
monoclinic
P21/c (No. 14)
12.5190(4)
33.126(1)
12.2897(5)
90
91.511(1)
90
5094.7(5)
4861, 3.0-46.0
4
orange, block
0.11 × 0.08 × 0.04
triclinic
P1h (No. 2)
9.866(2)
10.655(2)
19.045(4)
101.112(3)
98.820(3)
109.347(3)
1801.7(6)
2607, 3.0-46.0
2
red, block
0.28 × 0.10 × 0.05
triclinic
P1h (No. 2)
10.523(1)
10.665(1)
20.764(2)
95.787(1)
91.028(1)
110.780(1)
2170.2(6)
3163, 3.0-45.0
2
R (deg)
â (deg)
γ (deg)
V (Å3)
orientation rflns: no., 2θ range (deg)
Z
Dcalcd (g/cm3)
1.491
1.300
1.286
F000
2200.00
39.61
SMART
944.00
41.00
800.00
32.24
µ(Mo KR) (cm-1
diffractometer
radiation
)
Mo KR (λ ) 0.710 69 Å), graphite monochromated
temp (K)
126(1)
129(1)
138(1)
scan type
ω (0.3° per frame)
scan rate (s/frame)
data collected, 2θmax (deg)
no. of rflns measd
total
unique
Rint
10.0
49.4
20.0
49.6
20.0
46.5
22 703
8539
0.077
9224
5760
0. 086
5048
4557
0.056
transmissn factors
Tmax
Tmin
0.86
0.54
0.75
0.62
0.96
0.54
structure soln
direct methods (SIR92)
2501
224
11.17
0.070; 0.080; 0.130
1.4
0.00
3.07, -2.61
no. of obsd data (I > 3σ(I))
no. of params refined
rfln/param ratio
final residuals: R; Rw; Rall
goodness-of-fit indicatorb
max shift/error final cycle
4372
365
11.98
0.037; 0.040; 0.092
0.95
0.05
1.39, -1.70
3706
253
14.65
0.050; 0.062; 0.062
2.44
0.02
2.03, -3.28
a
max, min peaks, final diff map (e/Å3)
a
b
R ) ∑||Fo| - |Fc||/∑|Fo|; Rw ) [∑w(|Fo| - |Fc|)2/∑wFo2]1/2
.
Goodness of fit ) [∑w(|Fo| - |Fc|)2/(Nobservns - Nparams)]1/2
.
Ta ble 8. Selected Bon d Dista n ces (Å) a n d An gles
(d eg) for 10
NMR spectrum of 14a contains two resonances, a triplet
(δ 7.9, J PP ) 11 Hz) and a doublet (δ -17.7, J PP ) 11
Hz), in a 1:2 ratio. The corresponding resonances for
2
2
(a) Bond Distances
2
2
Ir-P1
Ir-P2
Ir-P3
2.357(3)
2.280(3)
2.274(3)
Ir-I1
Ir-I2
2.6697(8)
2.7086(8)
14b occur at δ 9.1 (t, J PP ) 14 Hz) and δ -9.2, (d, J PP
1
) 14 Hz). The H NMR spectra of 14a and 14b feature
2
hydride resonances at δ -12.10 (dm, J HP(trans) ) 124
Hz) and δ -10.12 (dm, 2J HP(trans) ) 125 Hz), respectively.
The 31P{1H} NMR spectrum of complex 15 in benzene-
d6 consists of a singlet (δ 1.40), and in the 1H NMR
spectrum the IrH resonance is observed at δ -12.42
(b) Bond Angles
P1-Ir-P2
P1-Ir-P3
P2-Ir-P3
I1-Ir-I2
I1-Ir-P1
87.6(1)
91.01(9)
88.0(1)
84.98(3)
88.83(7)
I1-Ir-P2
I1-Ir-P3
I2-Ir-P1
I2-Ir-P2
I2-Ir-P3
134.74(7)
137.20(7)
173.40(7)
98.34(7)
91.99(7)
2
(dm, J HP(trans) ) 96 Hz).
Consistent with the formulation of 14a as [Li(THF)n]-
{[PhBP3]IrH2I}, it was observed to react with PMePh2
(13 equiv, room temperature, 5.5 h) to give [PhBP3]Ir-
(PMePh2)H2 (5; by NMR spectroscopy) via the substitu-
tion of I- with the phosphine. Due to the lower stability
and transient nature of 14b relative to 14a , we have
been unable to observe its transformation to 5 upon
addition of PMePh2. The reaction of 15 with Me3SiCl (9
equiv, 80 °C, 24 h) gave [PhBP3]Ir(H)3SiMe350 (by NMR
spectroscopy).
Ta ble 9. Selected Bon d Dista n ces (Å) a n d An gles
(d eg) for 13
(a) Bond Distances
Ir-P1
Ir-P2
Ir-P3
2.337(7)
2.277(7)
2.255(8)
Ir-Cl1
Ir-Cl2
B-Cl3
2.331(7)
2.369(7)
1.93(3)
(b) Bond Angles
P1-Ir-P2
P1-Ir-P3
P2-Ir-P3
Cl1-Ir-Cl2
Cl1-Ir-P1
91.0(2)
Cl1-Ir-P2
Cl1-Ir-P3
Cl2-Ir-P1
Cl2-Ir-P2
Cl2-Ir-P3
137.1(3)
137.5(3)
171.8(3)
93.4(2)
90.7(2)
85.4(2)
83.9(3)
171.8(3)
Interestingly, the reactions of 10 and 11 with LiBHEt3
occur at substantially different rates. Reaction of the
diiodide 10 with 3 equiv of LiBHEt3 in benzene-d6 was
observed to produce 14a , and this was followed by the
slow, complete conversion to 15 over 36 h. On the other
hand, the addition of 3 equiv of LiBHEt3 to the dichlo-
ride 11 in benzene-d6 resulted in rapid and quantitative
formation of 15 (<5 min by NMR spectroscopy).
96.5(3)
reaction, free BEt3 was observed (by 11B NMR spectros-
copy). These ate complexes were characterized spectro-
scopically and by derivatization chemistry, since at-
tempts to isolate 14 and 15 resulted in decomposition.
The monohalide dihydride complexes 14a and 14b
have very similar spectroscopic properties. The 31P{1H}

4058 Organometallics, Vol. 21, No. 20, 2002
Feldman et al.
Sch em e 3
Ta ble 10. Selected Bon d Dista n ces (Å) a n d An gles
(d eg) for 16
(a) Bond Distances
Ir-P1
Ir-P2
Ir-P3
2.390(3)
2.218(3)
2.326(4)
Ir-C1
Ir-C2
2.08(1)
2.11(1)
(b) Bond Angles
P1-Ir-P2
P1-Ir-P3
P2-Ir-P3
C1-Ir-C2
C1-Ir-P1
90.2(1)
88.2(1)
87.2(1)
81.3(5)
173.9(4)
C1-Ir-P2
C1-Ir-P3
C2-Ir-P1
C2-Ir-P2
C2-Ir-P3
92.9(4)
97.2(4)
92.6(4)
118.5(4)
154.3(4)
between a square-based pyramid and that of complexes
10 and 13 (pseudo trigonal bipyramidal). Thus, P(1) and
C(1) are trans to one another with a P(1)-Ir-C(1) angle
of 174.2(6)°. The C(2)-Ir-P(3) angle of 154.2(7)° is
between those expected for a square-based pyramid
(180°) and a trigonal bipyramid (120°).
F igu r e 7. ORTEP diagram of [PhBP3]IrMe2 (16).
Two equivalents of methyllithium (1.4 M in Et2O)
reacted with 10 in benzene to give the pale red dimethyl
complex [PhBP3]IrMe2 (16) in 53% isolated yield, as
shown in eq 7. Although complex 16 appears to be stable
Discu ssion
Electr on ic P r op er ties of [P h BP 3]Ir . It has recently
been argued by Bergman and co-workers that the Cp*
ligand is more electron-donating toward iridium than
the TpMe ligand.2-4 They also suggested that this
2
difference is at least partly responsible for the enhanced
reactivity of Cp*(PMe3)Ir(Me)(OTf) and [Cp*(PMe3)-
IrMe]{B[3,5-C6H3(CF3)2]4} with respect to C-H activa-
tion relative to analogous TpMe complexes.2-4
2
The stretching frequencies of metal-bound carbonyls
are a gauge of the electron richness of the metal center
and thereby of the electron-donating abilities of the
ancillary ligands bound to the metal. A comparison of
in solution (65 °C, 2 days, benzene-d6), it decomposes
in the solid state and under vacuum. By 1H NMR
spectroscopy, the methyl groups are equivalent over a
wide temperature range (23 to -94 °C, toluene-d8), and
their protons appear as a broad resonance (δ 0.80,
benzene-d6). Likewise, the phosphorus atoms are equiva-
lent by 31P{1H} NMR spectroscopy (toluene-d8, δ -25.3,
23 to -94 °C), suggesting a dynamic structure for 16 in
solution.
51
2
IR data for iridium dicarbonyl complexes of TpMe
,
Cp*,52 and [PhBP3] (in hexanes, Table 5) suggests that
the relative electron-donating ability of these ligands
is [PhBP3] g Cp* > TpMe . A related dicarbonyl complex,
2
[(triphos)Ir(CO)2][BF4], prepared by Bianchini and co-
workers, has CO stretching frequencies of 2053 and
1954 cm-1 (measured as a Nujol mull).53 This cationic
Crystals of 16 were grown from the slow evaporation
of a benzene solution (room temperature), and the solid-
state structure was determined by X-ray diffraction
(Figure 7; selected bond distances and angles are given
in Table 10). The geometry of 16 is intermediate
(51) Ball, R. G.; Ghosh, C. K.; Hoyano, J . K.; McMaster, A. D.;
Graham, W. A. G. Chem. Commun. 1989, 341-342.
(52) Hoyano, J . K.; Graham, W. A. G. J . Am. Chem. Soc. 1982, 104,
3723-3725.
(53) Barbaro, P.; Bianchini, C.; Meli, A.; Peruzzini, M.; Vacca, A.;
Vizza, F. Organometallics 1991, 10, 2227-2238.

Zwitterionic Iridium Complexes
Organometallics, Vol. 21, No. 20, 2002 4059
complex therefore appears to be less electon-rich than
the isoelectronic [PhBP3]Ir(CO)2.
of such complexes to enforce octahedral coordination
geometries may be readily overwhelmed by electronic
factors.
It is somewhat surprising that the [PhBP3]Ir and
Cp*Ir fragments possess similar electronic properties,
given the assumption of cationic character for the metal
center in the former system. While CO stretching
frequencies provide a reasonable qualitative estimate
of the comparative electron richness between a series
of structurally related complexes bearing different
ligands, it is an approximation. The difference in CO
Coor d in a tion Geom etr ies a n d Ster ic Con sid er -
a tion s for [P h BP 3]Ir . The [PhBP3]Ir complexes re-
ported here exhibit a variety of coordination geometries.
In all of the crystallographically characterized com-
plexes with iridium, the [PhBP3] ligand maintains facial
coordination with all P-Ir-P angles close to 90°. Some
structures have the expected six-coordinate, octahedral
geometry for Ir(III) compounds, including allyls 2 and
3 as well as the highly distorted, cyclometalated tetra-
phosphine complex 4.
vibrational frequencies between Cp*Ir(CO)2, [TpMe ]Ir-
2
(CO)2, and [PhBP3]Ir(CO)2 may also be a consequence
of their different coordination geometries, and to that
extent a note of caution must be added in using this
gauge to order the relative donor strength of the three
ligands.54
Perhaps more interesting are the trivalent, five-
coordinate structures derived from [PhBP3]Ir. The mon-
omeric nature of the dihalides 10 and 13 was unex-
pected, given that [Cp*Ir(µ-X)X]2 (X ) Cl, Br, I)57 and
Since [PhBP3]Ir appears to be relatively electron-rich,
its complexes are expected to be more reactive toward
[TpMe Ir(µ-Cl)Cl]2 58 complexes are dimeric. Apparently,
2
oxidative additions than those of TpMe Ir. Indeed, there
2
dimerizations of 10 and 13 are prevented by the
significant steric bulk of [PhBP3]. However, dimerization
is observed when the halides are replaced with hydride
ligands, as [PhBP3]IrH2 is only observed as the dimer
{[PhBP3]Ir(H)(µ-H)}2 (8). A search of the CSD revealed
many examples of trivalent Cp*IrX2 complexes (where
X2 is an anionic ligand such as 1,2-dithiobenzene,59 1,2-
diaminobenzene,60 or (bis)thiohexafluorobenzene61), but
for Tp′Ir complexes, which maintain 90° N-Ir-N
angles, no such structures are known. Furthermore,
with Cp′ and Tp′ ancillary ligands there are no struc-
turally characterized complexes analogous to the five-
coordinate dimethyl species 16.
is a difference between the reactivities of allyl hydride
complexes derived from [PhBP3]Ir and TpMe Ir. Whereas
2
2 readily activates the Si-H bonds of secondary silanes
to give silylene complexes of the type [PhBP3](H)2Ird
SiR2, no reactions were observed10,50 between silanes
23
and the related complexes TpIr(H)(η3-C8H13
)
and
TpMe Ir(H)(η -C4H7).23 This may be due to the enhanced
susceptibility of [PhBP3]Ir complexes toward oxidative
additions, though it should be noted that mechanisms
involving a change in allyl hapticity (η3 to η1) or other
ligand dissociation may be responsible for this differ-
ence.
3
2
Another interesting comparison of related iridium
complexes is found in the protonation chemistry of LIr-
(PR3)H2 (where L is Tp′, Cp′, or [PhBP3]). The protona-
tion of a variety of Tp′Ir(PR3)H2 and Cp′Ir(PR3)H2
complexes has revealed a key difference between the
The stability of 5-coordinate 16 is surprising given
that all dimethyl complexes of Cp*Ir contain an ad-
ditional ligand such as PR3,62 CO,63 or DMSO,64 and
65
TpMe IrMe2(PMe3) is the only dimethyl derivative of
2
+
a Tp′Ir complex. Maitlis and co-workers have shown
that methylation of [Cp*Ir(µ-Cl)Cl]2 with Al2Me6 leads
to formation of a bimetallic methyl-bridged species of
the type [(Cp*IrMe3)2AlMe], from which cis- and trans-
[Cp*(Me)Ir(µ-CH2)]2, as well as Cp*IrMe4, are de-
rived.64,66,67
Cp′Ir and Tp′Ir fragments. While Cp′Ir(PR3)H3 com-
plexes are classical hydrides,35-37 Tp′Ir(PR3)(H2)(H)+
complexes are nonclassical hydrides,38,55 on the basis
of T1(min) NMR data and a neutron diffraction study
for [CpIr(PMe3)H3][BF4].36 For 6, the T1(min) value of
281 ( 5 ms indicates that it is the classical hydride
complex {[PhBP3]Ir(PMePh2)H3}{B[3,5-C6H3(CF3)2]4}.56
One explanation for the difference between these
protonated Tp′ and Cp′ complexes is that the more
electron-donating Cp′ ligands are better able to support
higher oxidation state Ir(V) hydride complexes, whereas
Tp′Ir is relatively electron-poor, thus favoring lower
valent, nonclassical Ir(III) hydride complexes. An al-
ternative explanation has been put forth suggesting that
Tp′ enforces an octahedral geometry at iridium (favoring
a six-coordinate, nonclassical hydride complex) while
Cp′ is more forgiving with respect to geometry, allowing
for a formally seven-coordinate, classical hydride com-
plex.8,13 However, since [PhBP3], like Tp′, coordinates
in a facial manner and the protonation of 5 gives a
classical hydride complex, it seems that the tendency
While 10 and 13 have pseudo-trigonal-bipyramidal
structures (with basal P-Ir-P angles restricted to ca.
90°), [PhBP3]IrMe2 (16) exhibits a distorted-square-
pyramidal geometry. This is consistent with the notion
that, for d6 ML5 complexes, a square-pyramidal geom-
etry is expected, except when π-donor ligands are
(57) Churchill, M. R.; J ulis, S. A. Inorg. Chem. 1979, 18, 1215-1221.
(58) May, S.; Reinsalu, P.; Powell, J . Inorg. Chem. 1980, 19, 1582-
1589.
(59) Xi, R.; Abe, M.; Suzuki, T.; Nishioka, T.; Isobe, K. J . Organomet.
Chem. 1997, 549, 117-125.
(60) Paek, C.; Ko, J . J .; Uhm, J . K. Bull. Kor. Chem. Soc. 1994, 15,
980-984.
(61) Garcia, J . J .; Torrens, H.; Adams, H. J . Chem. Soc., Dalton
Trans. 1993, 10, 1529-1536.
(62) Buchanan, J . M.; Stryker, J . M.; Bergman, R. G. J . Am. Chem.
Soc. 1986, 108, 1537-1550.
(63) Isobe, K.; Vazquez de Miguel, A.; Maitlis, P. M. J . Organomet.
Chem. 1983, 250, C25-C27.
(54) As a cautionary point, other comparative carbonyl model studies
for complexes supported by (phosphino)borate ligands have shown
surprisingly similar CO vibrational energies in comparison to Cp and
Tp ligands for structurally related carbonyl complexes: Betley, T. A.;
Thomas, J . C.; Peters, J . C. Manuscripts in preparation.
(55) Heinekey, D. M.; Oldham, W. J . J . Am. Chem. Soc. 1994, 116,
3137-3138.
(64) de Miguel, A. V.; Gomez, M.; Isobe, K.; Taylor, B. F.; Mann, B.
E.; Maitlis, P. M. Organometallics 1983, 2, 1724-1730.
(65) Tellers, D. M.; Bergman, R. G. Can. J . Chem. 2001, 79, 525-
528.
(66) Isobe, K.; Bailey, P. M.; Maitlis, P. M. Chem. Commun. 1981,
808-809.
(67) de Miguel, A. V.; Isobe, K.; Taylor, B. F.; Nutton, A.; Maitlis,
P. M. J . Chem. Soc., Chem. Commun. 1982, 758-759.
(56) Crabtree, R. H. The Organometallic Chemistry of the Transition
Metals, 2nd ed.; Wiley: New York, 1994.

4060 Organometallics, Vol. 21, No. 20, 2002
Feldman et al.
Sch em e 4
present (as with 10 and 13).68,69 In the case with
π-donors, a distorted-trigonal-bipyramidal structure is
favored, because a π-donor in the equatorial plane can
interact with the LUMO on the metal.70 Interestingly,
the only other five-coordinate dialkyl iridium species
which have been crystallographically characterized are
R2Ir[N(SiMe2CH2PPh2)2], where R2 ) (CH2Ph)2,71 (Me)-
(CH2CMe3),72 and Cp2Ta(CH2)2Ir(CO)2(PEt3).73 All three
of these have distorted-trigonal-bipyramidal geometries.
For all of the five-coordinate [PhBP3]Ir complexes (10,
11, 13, and 16), only a single 31P NMR resonance is
observed over the temperature range of -94 to 23 °C.
A dimeric structure of the type {[PhBP3]Ir(X)(µ-X)}2
would give rise to two coupled resonances, as would
trigonal-bipyramidal or square-based-pyramidal struc-
tures. This implies that the solution structures are
monomeric and fluxional.
C-H Activa tion Ch em istr y. We have observed
several examples of intramolecular activation of C-H
bonds with [PhBP3]Ir compounds, beginning with the
addition of [Li(TMED)][PhBP3] to [(alkene)2IrCl]2 to give
allyl complexes 2 and 3 via oxidative addition of
coordinated alkene (Scheme 1). The metalation of phen-
yl substituents on phosphine ligands has also been
observed. The photolysis of 5 led to elimination of H2
and formation of phenyl-metalation products A and B
(eq 3), and the reaction of 2 with PMe3 gave a similar
product, 4 (eq 1). Presumably both of these ligand-
activation products form via intermediate, highly reac-
tive, 16-electron species of the type [PhBP3]Ir(PR3),
which then rapidly undergo ortho metalation of a
P-phenyl group. For the related compound Cp*Ir(PMe3)-
H2, it has been shown that photolysis generates H2 and
[Cp*Ir(PMe3)], which then activates the C-H bonds of
numerous alkanes and arenes. Furthermore, intramo-
lecular metalation of a phenyl C-H bond was observed
along with benzene activation upon the generation of
[Cp*Ir(PPh3)].19
Although there is no evidence for intermolecular C-H
activation in reactions of the [PhBP3]Ir complexes
described above, we have observed chemistry consistent
with intermolecular C-D activation of benzene-d6.
While thermolysis of 9 in THF-d8 led to quantitative
formation of COE and dimer 8 (Scheme 2), use of
2
benzene-d6 as the solvent gave 8 and COE-d14 (by H
NMR spectroscopy and GC/MS), along with an increased
amount of C6D5H (by 1H NMR spectroscopy). It is
noteworthy that no partially deuterated COE is pro-
duced in this reaction (by GC/MS). Photolysis of 9
(benzene-d6, 6 h) resulted in loss of COE (undeuterated)
to form dimer 8 (ca. 90%) and elimination of H2 to form
the allyl 2 (ca. 10%).
In principle, there are three possible pathways whereby
9 can open a coordination site and activate benzene-d6.
In path A (Scheme 4), migratory insertion followed by
oxidative addition of the C-D bond of benzene would
give intermediate C. In order for COE-d14 to be formed
exclusively, the rate of reductive elimination of benzene
from C must be significantly greater than the elimina-
tion of cyclooctane (not observed), which seems unlikely.
On the other hand, dissociation of COE from 9 would
generate [PhBP3]IrH2, which could then add benzene-
(68) Albright, T. A.; Burdett, J . K.; Whangbo, M.-H. Orbital Interac-
tions in Chemistry; Wiley: New York, 1985.
(69) Rossi, A. R.; Hoffmann, R. Inorg. Chem. 1975, 14, 365.
(70) Thorn, D. L.; Hoffmann, R. New J . Chem. 1979, 3, 39-45.
(71) Fryzuk, M. D.; MacNeil, P. A.; Massey, R. L.; Ball, R. G. J .
Organomet. Chem. 1989, 368, 231-247.
(72) Fryzuk, M. D.; MacNeil, P. A.; Ball, R. G. J . Am. Chem. Soc.
1986, 108, 6414-6416.
(73) Hostetler, M. J .; Butts, M. D.; Bergman, R. G. Inorg. Chim.
Acta 1992, 200, 377-392.

Zwitterionic Iridium Complexes
Organometallics, Vol. 21, No. 20, 2002 4061
obtained from commercial suppliers and used as received.
Elemental analyses were performed by the Microanalytical
Laboratory in the College of Chemistry at the University of
California, Berkeley. FT-infrared spectra were recorded as KBr
pellets or as Nujol mulls on a Mattson FTIR 3000 instrument
or on a Mattson Infinity FTIR.
NMR Mea su r em en ts. 1H, 31P, 29Si, 11B, and 13C NMR
spectra were recorded at ambient temperature, unless other-
wise noted, on a Bruker DRX-500 instrument equipped with
a 5 mm broad-band probe and operating at 500.1 MHz (1H),
125.8 MHz (13C), 160.46 MHz (11B), 99.4 MHz (29Si), and 202.5
MHz (31P) or on a Bruker AMX-400 with a 5 mm quadra-
nuclear probe at 400.1 MHz (1H) and 162.0 MHz (31P).
Chemical shifts are reported in ppm downfield from SiMe4 and
were referenced to solvent peaks (1H, 13C) or external 85% H3-
PO4 (31P) or external Et2O‚BF3 (11B). Bruker XWINNMR
software (ver. 2.1) was used for all processing.
d6 (path B). The resulting partially deuterated complex,
9-dx, could undergo migratory insertion to transfer
deuterium to COE. In this case, the formation of only
COE-d14 requires that benzene oxidative addition is
much faster than dimerization of [PhBP3]IrH2. A third
possibility (path C) involves the reductive elimination
of H2 to give [PhBP3]Ir(η2-COE), which then activates
benzene-d6 (but does not activate COE to give allyl 2).
Currently, the operative mechanism is not known, but
it is interesting to note that a mechanism analogous to
path B was suggested in a study of the photolysis of
Me2
TpMe Ir(H)2(COE), which gives Tp Ir(H)(C6H5)P(OMe)3
2
in the presence of P(OMe)3.74 Attempts to use 9 as an
H/D exchange catalyst by heating 10 equiv of COE with
9 in benzene-d6 gave 3 turnovers of COE-d14 (and no
partially deuterated COE) before all of the catalyst was
irreversibly converted to 8.
X-r a y Cr ysta llogr a p h y. Gen er a l Con sid er a tion s. The
single-crystal analyses were carried out at the UC Berkeley
CHEXRAY crystallographic facility. Measurements were made
Con clu sion
on
a Bruker SMART CCD area detector with graphite-
monochromated Mo KR radiation (λ ) 0.710 69 Å). Data were
integrated by the program SAINT, corrected for Lorentz and
polarization effects, and analyzed for agreement and possible
absorption using XPREP. Empirical absorption corrections
were made using SADABS. Structures were solved by direct
methods and expanded using Fourier techniques. All calcula-
tions were performed using the teXsan crystallographic soft-
ware package. Selected crystal and structure refinement data
are summarized in Tables 1 and 7. All crystals were mounted
on a glass fiber using Paratone N hydrocarbon oil.
Several iridium complexes featuring the recently
introduced tripodal phosphine PhB(CH2PPh2)3 have
-
been prepared and characterized. These complexes have
steric and electronic properties that are distinct from
related Cp′Ir and Tp′Ir compounds. It is clear that
[PhBP3] is more sterically encumbering than Cp* and
TpMe and is octahedral-enforcing in that it tenaciously
2
maintains 90° P-Ir-P bond angles, even in five-
coordinate structures. On the other hand, like Cp*,
[PhBP3] possesses soft donor atoms and yields electron-
rich iridium complexes. This is apparent from the
spectroscopic comparison of iridium dicarbonyl com-
plexes and from the formation of the classical hydride
complex {[PhBP3]Ir(PMePh2)H3}{B[3,5-C6H3(CF3)2]4}
(6).
Con sid er a tion s for 2‚THF . The hydrogen atoms on the
allyl fragment of the cyclooctene ligand were located in the
difference electron density map and their positions refined
with fixed thermal parameters. The remaining hydrogens were
included in calculated idealized positions but not refined.
Except for boron, all non-hydrogen atoms were refined aniso-
tropically.
Among the new complexes are allyl hydrides 2 and
3, from which most of the other compounds are derived,
and the synthetically useful dihalides 10 and 11. Allyl
hydride 2 is a versatile starting material, as it serves
as a masked source of [PhBP3]Ir or [PhBP3]IrH2,
depending on the specific reaction conditions employed.
This work has demonstrated the tendency of unsatur-
ated, intermediate [PhBP3]Ir complexes to undergo
C-H activation reactions. Although this chemistry has
mostly been limited to intramolecular activation of the
[PhBP3] ligand, we have observed catalytic H/D ex-
change between benzene-d6 and COE.
Con sid er a tion s for 3‚C6H6. Except for boron, all non-
hydrogen atoms were refined anisotropically; the hydrogen
atom positions were calculated but not refined.
Con sid er a tion s for 4‚CH2Cl2‚C5H12. With the exception
of disordered solvent atoms and boron, all non-hydrogen atoms
were refined anisotropically. A dichloromethane molecule was
modeled with one isotropic carbon atom, one anisotropic
chlorine with full occupancy, a second anisotropic chlorine with
0.83 occupancy, and a third isotropic chlorine with 0.17
occupancy. A second, highly disordered solvent molecule
(possibly pentane) was modeled as a number of carbon atoms
(some full and some partial occupancy, all refined isotropically)
with the following occupancies: C(49), 0.75; C(50), 0.75; C(51),
0.75; C(52), 0.70; C(53), 0.75; C(54), 0.40; C(55), 1.0; C(56), 1.0;
C(57), 0.70; C(58), 0.65. These values were obtained by refining
the occupancy of these atoms. Hydrogen atom positions were
calculated but not refined.
Exp er im en ta l Section
Gen er a l Con sid er a tion s. All experiments were performed
under dry nitrogen using standard Schlenk or drybox tech-
niques. Ether and THF were distilled under nitrogen from
sodium benzophenone ketyl. Dichloromethane, TMED, and
acetonitrile were distilled from CaH2. Toluene was distilled
from potassium. To remove olefin impurities, pentane and
benzene were pretreated with concentrated H2SO4, 0.5 N
KMnO4 in 3 M H2SO4, NaHCO3, and then anhydrous MgSO4.
Benzene-d6 was distilled from Na/K alloy. [Ir(COE)2Cl]2 was
prepared according to the literature procedure.75 Carbon
monoxide was obtained from Scott Specialty Gases, Inc.
Dihydrogen was obtained from Praxair. Other chemicals were
Con sid er a tion s for 8‚C6H6. The iridium, phosphorus, and
six solvent carbon atoms (C46-C51) were refined anisotropi-
cally, and all other non-hydrogen atoms were refined isotro-
pically. Hydrogen atom positions were calculated but not
refined.
Con sid er a tion s for 10‚2C7H8. The iridium and phospho-
rus atoms as well as the toluene carbon atoms were refined
anisotropically, while the remaining carbon atoms and boron
were refined isotropically. The non-toluene carbon atoms were
not refined anisotropically. The hydrogen atom positions were
calculated but not refined.
Con sid er a tion s for 13. The iridium, phosphorus, and
chlorine atoms were refined anisotropically, the boron and
carbon atoms were refined isotropically, and the hydrogen
atom positons were calculated but not refined.
(74) Ferrari, A.; Polo, E.; Ruegger, H.; Sostero, S.; Venanzi, L. M.
Inorg. Chem. 1996, 35, 1602-1608.
(75) Herde, J . L.; Lambert, J . C.; Senoff, C. V. Inorg. Synth. 1974,
15, 18-20.

4062 Organometallics, Vol. 21, No. 20, 2002
Feldman et al.
Con sid er a tion s for 16. The iridium and phosphorus atoms
were refined anisotropically, and the boron and carbon atoms
were refined isotropically. The hydrogen atom positions were
calculated but not refined.
2148 m (IrH). Anal. Calcd for C48H47BIrP3: C, 62.68; H, 5.15.
Found: C, 62.51; H, 5.55. Mp: 257-260 °C dec.
{P h B[(CH 2P P h 2)2(CH 2P P h C6H 4)]}Ir (H )(P Me3) (4). A
thick-walled 100 mL flask fitted with a PTFE stopcock was
charged with 3 (0.143 g, 0.145 mmol), a magnetic stir bar, and
4 mL of benzene. Addition of PMe3 (22 µL, 0.21 mmol) via
syringe resulted in complete dissolution of the iridium com-
pound. The flask was placed in an oil bath maintained at 55
°C for 2.5 days. A small amount of solid was removed by
filtration, and the solvent was removed under vacuum. Crys-
tallization from CH2Cl2 at -35 °C gave 0.127 g (92%) of
[Li(TMED)][P h B(CH2P P h 2)3] (1). A slurry of Li(TMED)-
CH2PPh2 (12.54 g, 0.039 mol) in 225 mL of Et2O was stirred
and cooled to -78 °C. A toluene (15 mL) solution of PhBCl2
(2.06 g, 0.013 mol) was then added dropwise via cannula. After
3 h, the solution was warmed to room temperature and was
stirred for 12 h, giving a colorless precipitate. The solution
was filtered, and the precipitate was washed with Et2O (2 ×
25 mL). Phosphine 1 was extracted from the precipitate with
ca. 50 °C toluene (2 × 200 mL). The extracts were combined,
concentrated, and slowly cooled to -80 °C to give 7.55 g (72%)
1
spectroscopically pure 4‚2CH2Cl2. H NMR (CD2Cl2): δ 7.92,
7.73, 7.58, 7.42, 7.32, 7.26-7.10, 7.04, 6.90, 6.84, 6.65, 6.34
(aryl), 2.37 (m, 1 H, BCHH′), 2.20 (m, 1 H, BCHH′), 1.71 (d,
1
of colorless, crystalline 1. H NMR (THF-d8): δ 7.42 (d, 2 H,
2
3J HP ) 9 Hz, 9 H, PMe3), -9.47 (dm, J HP(trans) ) 121 Hz, 1 H,
o-PhB(CH2PPh2)3), 7.21 (m, 12 H, PhB(CH2PPh2)3), 6.96 (m,
18 H, PhB(CH2PPh2)3), 6.63 (m, 2 H, m-PhB(CH2PPh2)3), 6.51
(t, 1 H, p-PhB(CH2PPh2)3), 2.31 (s, 4 H, Me2NCH2CH2NMe2),
2.16 (s, 12H, Me2NCH2CH2NMe2), 1.23 (br m, 6 H, PhB(CH2-
PPh2)3). 31P{1H} NMR (THF-d8): δ -12.4 (s). 13C{1H} NMR
(THF-d8): δ 149.0, 134.9, 134.2, 129.8, 129.0, 127.7, 126.4,
125.6, 121.7 (aryl), 58.9 (Me2NCH2CH2NMe2), 46.4 (Me2-
NCH2CH2NMe2). 11B NMR (C6D6): δ -14.0 (s). Anal. Calcd
for C51H57BLiN2P3: C, 75.75; H, 7.10. Found: C, 75.43; H, 6.91.
[P h BP 3]Ir (η3-C8H13)H (2). A stirred slurry of [(COE)2IrCl]2
(1.09 g, 1.21 mmol) in benzene (15 mL) was added to a stirred
slurry of 1 (1.96 g, 2.42 mmol) in benzene (35 mL) to give a
dark green solution. After 15 h, all solvent was removed in
vacuo and the resulting tan/green solid was washed with
pentane (2 × 10 mL). Complex 2 was then extracted with 40
°C benzene and crystallized from toluene in three crops (87%
yield). 1H NMR (benzene-d6): δ 8.10 (d, 2 H, o-PhB(CH2PPh2)3),
7.8-6.7 (m, 30 H, PhB(CH2PPh2)3), 7.65 (m, 2 H, m-PhB(CH2-
PPh2)3), 7.41 (t, 1 H, p-PhB(CH2PPh2)3), 4.90 (m, 1 H, CH),
3.57 (m, 2 H, CH), 3.13 (m, 2 H, CH2), 2.78 (m, 2 H, CH2),
IrH). 31P{1H} NMR (CD2Cl2): δ -3.13 (pseudo q, 2J PP(cis) ) 18
2
2
Hz), -19.94 (m), -58.26 (ddd, J PP(trans) ) 283 Hz, J PP(cis)
)
21 Hz, 2J ′PP(cis) ) 16 Hz), -69.90 (ddd, J PP(trans) ) 283 Hz,
2
2J PP(cis) ) 26 Hz, J ′PP(cis) ) 17 Hz). 13C{1H} NMR (CD2Cl2): δ
2
157.1, 142.9, 142.2, 141.9, 135.3, 134.2, 134.1, 133.4, 133.3,
133.1, 132.4, 132.2, 130.6, 130.0, 129.5, 128.8, 128.0, 127.9,
127.6, 127.4, 124.1, 122.2 (aryl), 25.3 (br m, BCH2P), 23.5 (br
m, BCH2P), 22.8 (dm, J ) 32 Hz, PCH3), 9.8 (br m, BCH2P).
IR (KBr, cm-1): 3045 br m, 3002 w, 2908 w, 2882 w, 2077 br
m (IrH), 1480 m ([PhBP3]), 1433 s ([PhBP3]), 1089 m, 951 m,
921 m, 848 w, 735 s, 695 s, 514 s, 496 w, 444 w. Anal. Calcd
for 4‚2CH2Cl2 (C50H54BIrP4Cl4): C, 53.44; H, 4.84. Found: C,
53.72; H, 4.80. Mp: 260-262 °C.
[P h BP 3]Ir (P MeP h 2)H2 (5). A thick-walled 100 mL flask
fitted with a PTFE stopcock was charged with 3 (0.168 g, 0.170
mmol), PMePh2 (0.036 g, 0.180 mmol), a magnetic stir bar,
and 3 mL of benzene. The solution was stirred and heated to
80 °C for 24 h, during which time the solution turned red.
Volatile materials were removed in vacuo, and off-white 5 was
recrystallized in 46% yield via diffusion of pentane into a THF
2.03 (m, 2 H, PhB(CH′2PPh2)(CH2PPh2)2), 1.88 (m, 4 H, PhB-
1
solution of 5. H NMR (benzene-d6): δ 8.23 (d, J ) 10 Hz, 2
2
(CH′2PPh2)(CH2PPh2)2), 1.35 (m, 5 H, CH2), -12.55 (dt, J HP
-
H, o-PhB(CH2PPh2)3), 7.9-6.7 (m, 43 H, remaining [PhBP3]
aryl, MePPh2), 2.38-2.09 (m, 4 H, BCH2P trans to H), 1.73
(d, 2J HP ) 17 Hz, 2 H, BCH2P trans to PMePh2), 0.51 (dd, 2J HP
2
(trans) ) 150 Hz, J HP(cis) ) 14 Hz, 1 H, IrH). 31P{1H} NMR
2
(benzene-d6): δ -7.77 (d, J PP ) 22 Hz), -13.37 (br). 13C{1H}
4
2
NMR (THF-d8): δ 133.2, 133.1, 132.8, 132.0, 129.2, 128.9,
124.8 (aryl), 93.2 (HC[(CH)2(CH2)5)]), 56.9 (HC[(CH)2(CH2)5)]),
39.1 (HC[(CH)2(CH2)5)]), 30.7 (HC[(CH)2(CH2)5)]), 26.0 (HC-
[(CH)2(CH2)5)]). 11B NMR (C6D6): δ -12.0 (s). IR (Nujol, cm-1):
2143 m (IrH). Anal. Calcd for C53H55BIrP3: C, 64.43; H, 5.61.
Found: C, 64.33; H, 5.51.
) 8 Hz, J HP ) 2 Hz, 3 H, PCH3Ph2), -11.04 (dm, J HP ) 107
Hz, 2 H, IrH2). 31P{1H} NMR (benzene-d6): δ -0.98 (dt, 2J PP(trans)
) 285 Hz, J PP(cis) ) 21 Hz, 1 P, [PhBP3] trans to PMePh2),
-10.42 (t, J PP(cis) ) 21 Hz, 2 P, [PhBP3] trans to H), -16.84
2
2
(dt, J PP(trans) ) 285 Hz, J PP(cis) ) 21 Hz, 1 P, PMePh2). 13C-
{1H} NMR (THF-d8): δ 144.7 143.1, 141.1, 139.6, 134.5, 133.4,
132.9, 132.7, 130.1, 129.3, 129.2, 128.8, 128.6, 128.1, 127.9,
123.9 (aryl), 20.8 (br, BCH2P), 11.5 (d, 1J CP ) 27 Hz, PMePh2).
IR (KBr, cm-1): 3055 br m, 2990 br m, 2979 br m, 2157 br m
(IrH), 2053 s (IrH), 1482 m ([PhBP3]), 1433 s ([PhBP3]), 1089
s, 922 m, 887 s, 849 w, 738 s, 699 s, 595 w, 514 s, 481 s, 416
w. Anal. Calcd for C58H54BIrP4: C, 60.17; H, 5.05. Found: C,
60.23; H, 4.92. Mp: 160-164 °C dec.
2
2
[P h BP 3]Ir (η3-C3H5)H (3). A thick-walled 250 mL flask
fitted with a PTFE stopcock was charged with [(COE)2IrCl]2
(0.691 g, 0.771 mmol), a magnetic stir bar, and 75 mL of THF.
The orange solution was cooled to -78 °C with a dry ice/
acetone bath and degassed in vacuo. Propene (1 atm) was
introduced and allowed to saturate the solution for 2 min, at
which point the flask was cooled with liquid nitrogen to give
a frozen yellow solution. [Li(TMED)][PhB(CH2PPh2)3] (1.250
g, 1.55 mmol) was dissolved in 25 mL of THF and added to
the frozen solution, which was then warmed to room temper-
ature and was stirred for 24 h. Solvent was removed in vacuo,
and the solid residue was triturated with pentane (3 × 10 mL).
The product was extracted with benzene (2 × 30 mL) and
recrystallized from THF at -80 °C to give 1.028 g (72%) of
P h otolysis of 5. A Pyrex, PTFE-capped NMR tube contain-
ing 0.5 mL of a benzene-d6 solution of 5 (0.010 g, 0.093 mmol)
was irradiated under N2 in a Rayonet photolysis apparatus
for 13 h, during which time the conversion to metalation
products (ultimately A and B in a 2:5 ratio) was monitored by
NMR spectroscopy. The structure assignments are based on
1
comparisons of H and 31P{1H} NMR data to those of meta-
1
lation product 4. Although complete assignment of the 1H NMR
spectrum was not possible, due to the presence of many
overlapping resonances in the methylene region (δ 1.40-2.44;
12 inequivalent BCHH′P resonances for A + B) and in the
aryl region (δ 6.30-7.75; 56 inequivalent aryl resonances for
A + B), the PCH3 and IrH resonances were readily identified.
colorless, crystalline 3 in three crops. H NMR (benzene-d6):
δ 8.09 (d, J ) 7 Hz, 2 H, o-PhB(CH2PPh2)3), 7.8-6.7 (m, 30 H,
PhB(CH2PPh2)3), 7.65 (m, 2 H, m-PhB(CH2PPh2)3), 7.41 (t, J
) 7 Hz, 1 H, p-PhB(CH2PPh2)3), 4.17 (m, 1 H, HC(CHH′)2),
3.26 (m, 2 H, HC(CHH′)2), 2.23 (d, J ) 6 Hz, 2 H, HC(CHH′)2).
2.0-1.84 (m, 6 H, PhB(CH2PPh2)), -12.79 (dt, 2J HP(trans) ) 135
2
Hz, J HP(cis) ) 13, Hz 1 H, IrH). 31P{1H} NMR (benzene-d6): δ
1
Data for A are as follows. H NMR (benzene-d6): δ 0.87 (dd,
-7.83 (d, J pp ) 21 Hz, 2 P), -16.67 (t, 1 P). 13C{1H} NMR
(benzene-d6): δ 132.3, 132.2, 132.1, 132.0, 131.1, 131.0, 128.7,
124.0 (aryl), 92.9 (HC(CH2)2), 33.7 (HC(CH2)2), 14.1 (br PhB-
(CH2PPh2)). 11B NMR (C6D6): δ -12.4 (s). IR (benzene, cm-1):
2J HP ) 10 Hz, 4J HP ) 3 Hz, 3 H, PCH3Ph2), -9.03 (dm, 3J HP(trans)
) 119 Hz, 1 H, IrH). 31P{1H} NMR (benzene-d6): δ -3.81 (dt,
2
2
2J PP(trans) ) 306 Hz, J PP(cis) ) 21 Hz), -16.18 (q, J PP(cis) ) 18
2
2
Hz), -25.59 (q, J PP(cis) ) 17 Hz), -98.30 (dt, J PP(trans) ) 305

Zwitterionic Iridium Complexes
Organometallics, Vol. 21, No. 20, 2002 4063
2
Hz, J PP(cis) ) 18 Hz). Data for B are as follows. 1H NMR
w, 741 s, 695 s, 515 s, 481 w. Anal. Calcd for C53H57IrP3B: C,
64.29; H, 5.80. Found: C, 64.55; H, 6.05. Mp: 187-188 °C dec.
(benzene-d6): δ 1.95 (dd, 2J HP ) 8 Hz, 4J HP ) 2 Hz, 3 H, PCH3-
Ph2), -9.31 (dm, J HP(trans) ) 289 Hz, 1 H, IrH). 31P{1H} NMR
3
[P h BP 3]Ir I2 (10). Allyl 2 (0.532 g, 0.538 mmol) was stirred
in 8 mL of 3:2 benzene/acetonitrile (15 mL) for 20 min to give
a colorless solution. A 7 mL solution of I2 in benzene was added
to the solution of 2, generating a blood red solution of 10. The
solvent was removed in vacuo, and the dark purple crystalline
product was washed with pentane (3 × 10 mL) to aid in COE
removal, yielding 10 in 94% yield (0.569 g). X-ray-quality
crystals were grown from a concentrated toluene solution at
-35 °C. 1H NMR (benzene-d6): δ 7.94 (d, J ) 7 Hz, 2 H, o-PhB-
(CH2PPh2)3), 7.63 (m, 2 H, m-PhB(CH2PPh2)3), 7.55 (m, 12 H,
PhB(CH2PPh2)3), 7.41 (t, J ) 7 Hz, 1 H, p-PhB(CH2PPh2)3),
6.83 (m, 6 H, PhB(CH2PPh2)3), 6.69 (m, 12 H, PhB(CH2PPh2)3),
(benzene-d6): δ -6.91 (dt, 2J PP(trans) ) 309 Hz, 2J PP(cis) ) 21 Hz),
-9.81 (q, 2J PP(cis) ) 19 Hz), -24.89 (q, 2J PP(cis) ) 20 Hz), -104.87
2
2
(dt, J PP(trans) ) 311 Hz, J PP(cis) ) 20 Hz).
Obser va tion of {[P h BP 3]Ir (P MeP h 2)H3}{B[3,5-C6H3-
(CF 3)2]4} (6). Compound 5 (0.0078 g, 0.0072 mmol) was
dissolved in 0.5 mL of CD2Cl2 to give a colorless solution. To
this solution was added [H(OEt2)2]{B[3,5-C6H3(CF3)2]4} (0.0071
g, 0.0071 mmol), which gave an orange solution. In a PTFE-
sealed NMR tube a variable-temperature T1(min) determina-
tion was carried out on the IrH resonance of 6 using the null
method on a Bruker DRX-500 instrument. The T1(min) value
for the IrH resonance of 6 was determined to be 281 ( 5 ms
at 255 K. Similarly, the T1(min) value for the IrH resonance
2
1.91 (br d, J HP ) 10 Hz, 6 H, PhB(CH2PPh2)3). 31P{1H} NMR
(benzene-d6): δ 4.34 (s). 13C{1H} NMR (CD2Cl2): δ 134.0, 133.7,
132.1, 130.9, 128.4, 128.21 (aryl), 14.46 (br, PhB(CH2PPh2)3).
11B NMR (C6D6): δ -9.8 (s). IR (KBr, cm-1): 2920 m, 2656 s,
2448 w, 1481 m ([PhBP3]), 1434 s ([PhBP3]), 1160 w, 994 w,
971 w, 925 w, 863 w, 740 m, 693 s, 514 s, 485 w, 445 w. Anal.
Calcd for C45H41BIrP3I2: C, 47.76; H, 3.65. Found: C, 48.13;
H, 4.15. Mp: 252-260 °C (238 °C dec).
1
of 5 was determined to be 274 ( 5 ms at 245 K in CD2Cl2. H
NMR (CD2Cl2): δ 7.73, 7.57, 7.36, 7.29, 6.95, 6.86 (aryl), 2.06
2
(br, 2 H, BCH2P), 1.91 (br, 4 H, BCH2P), 0.53 (d, J HP ) 9 Hz,
3 H, PMePh2), -11.21 (dm, 2J HP ) 112 Hz, 4 H, IrH3). 31P{1H}
2
NMR (CD2Cl2): δ -6.20 (br d, J PP(trans) ) 286 Hz, 1 P, BPP2
trans to PMePh2), -14.76 (br, 2 P, BPP′2), -19.23 (dt, 2J PP(trans)
2
) 286 Hz, J PP(cis) ) 19 Hz, 1 P, PMePh2).
[P h BP 3]Ir Cl2 (11). Allyl 3 (0.453 g, 0.492 mmol) was
dissolved in 9 mL of 7:3 benzene/carbon tetrachloride. This
solution was stirred in a PTFE-sealed vessel at 65-70 °C for
7.5 days, over which time the solution turned orange. Note
that higher temperatures lead to formation of the chloroborate
12. This reaction is readily monitored by 31P{1H} NMR
spectroscopy to ensure that conversion of 3 to 11 occurs cleanly.
When the mixture was cooled to room temperature, orange
crystals deposited on the sides of the flask (0.093 g). The
remaining product was isolated as an orange powder (0.451
g) by removing solvent in vacuo and washing the resulting
solid with pentane (3 × 15 mL). Total yield: 97%. 1H NMR
(benzene-d6): δ 7.96 (d, J ) 7 Hz, 2 H, o-PhB(CH2PPh2)3), 7.64
(m 15 H, m-PhB(CH2PPh2)3), 7.44 (t, J ) 7 Hz, 1 H, p-PhB-
(CH2PPh2)3), 6.78 (m, 6 H, PhB(CH2PPh2)3), 6.66 (m, 12 H,
PhB(CH2PPh2)3), 1.82 (br d, 2J HP ) 9 Hz, 6 H, PhB(CH2PPh2)3).
31P{1H} NMR (benzene-d6): δ 4.92 (s). 13C{1H} NMR (CD2-
Cl2): δ 133.5, 132.2, 131.0, 128.5, 128.2, 125.3 (aryl), 12.9 (br,
PhB(CH2PPh2)3). 11B NMR (C6D6): δ -9.7 (s). IR (KBr, cm-1):
3055 br m, 1478 m ([PhBP3]), 1434 s ([PhBP3]), 1160 m, 1089
s, 917 m, 741 s, 694 s, 684 s, 483 m, 440 w. Anal. Calcd for
[P h BP 3]Ir (CO)2 (7). A thick-walled 100 mL flask fitted
with a PTFE stopcock was charged with 3 (0.125 g, 0.136
mmol), a magnetic stir bar, and 4 mL of benzene. The colorless
solution was then degassed with two freeze-pump-thaw
cycles, and carbon monoxide (1 atm) was introduced. The
solution was heated at 80 °C for 5 days, during which time it
turned yellow. Solvent was removed in vacuo, and the resulting
solid was washed with pentane (3 mL) and dried under
vacuum. Compound 7 was isolated as a pale yellow solid (0.091
g, 72%). 1H NMR (benzene-d6): δ 8.05 (d, J ) 7 Hz, 2 H, o-PhB-
(CH2PPh2)3), 7.65 (m, 2 H, m-PhB(CH2PPh2)3), 7.40 (m, 13 H,
3
aryl), 6.78 (m, 18 H, aryl), 1.84 (br d, J HP ) 11 Hz, 6 H, PhB-
(CH2PPh2)). 31P{1H} NMR (benzene-d6): δ -10.59 (s). 13C{1H}
NMR (benzene-d6): δ 187.9 (q, 2J CP ) 24 Hz, CO), 138.6, 132.7,
129.8, 129.1, 126.3, 125.3 (aryl), 14.7 (br) PhB(CH2PPh2). 11B
NMR (C6D6): δ -11.7 (s). IR (hexanes, cm-1): 3050 br w, 2905
br w, 2024 s (CO), 1940 s (CO), 1481 w ([PhBP3]), 1434 m
([PhBP3]), 1160 w, 1091 m, 917 w, 740 m, 696 s, 551 w, 515 s,
481 w, 438 w. Anal. Calcd for C47H41BIrP3: C, 60.45; H, 4.43.
Found: C, 60.30; H, 4.70. Mp: 256-260 °C dec.
{[P h BP 3]Ir (µ-H)(H)}2 (8). An NMR tube fitted with a
PTFE valve was charged with 3 (0.025 g, 0.027 mmol) and ca.
0.6 mL of benzene-d6. After two freeze-pump-thaw cycles, 1
atm of H2 was introduced. The NMR tube was heated to 80
°C for 2 days, during which time orange crystals grew at the
bottom of the tube. Crystalline 8 was isolated in 75% yield
(0.018 g). IR (KBr, cm-1): 2114 (terminal IrH), 1088 (bridging
IrH). Anal. Calcd for C90H88P6Ir2B2: C, 61.36; H, 5.03. Found:
C, 61.46; H, 4.96. Mp: >260 °C.
[P h BP 3]Ir (H)2(COE) (9). A 5 mL THF solution of 2 (0.098
g, 0.099 mmol) and COE (0.035 g, 0.31 mmol) in a PTFE-sealed
vessel was degassed with three freeze-pump-thaw cycles, and
1 atm of H2 was introduced. Over the 11.5 h of reaction time
the solution became pale orange, and a small amount of
crystalline 8 formed (by IR spectroscopy). The solution was
filtered through fine glass fiber filter paper, and the solvent
was removed in vacuo, giving off-white 9 (0.058 g, 59%). 1H
NMR (THF-d8): δ 7.69 (m, 8 H, aryl), 7.0-7.23 (m, 18 H, aryl),
6.80 (m, 4 H, aryl), 3.78 (br, 2 H, COE CH), 2.45 (m, 2 H, CH2),
2.19 (m, 2 H, CH2), 1.65 (m, 6 H, CH2), 1.48 (m, 4 H, CH2),
1.31 (m, 2 H, CH2), 0.94 (m, 2 H, CH2). 31P{1H} NMR (THF-
C
45H41BIrP3Cl2: C, 56.97; H, 4.36. Found: C, 56.76; H, 4.51.
Mp: >260 °C.
Obser va tion of [P h BP 3]Ir (COE)(MeCN) (12). Complex
12 forms upon dissolving 2 in benzene-d6/CD3CN, and it is
1
converted back to 2 upon solvent removal in vacuo. H NMR
(benzene-d6/CD3CN): δ 7.78 (m, 6 H, aryl), 7.31 (t, J ) 7 Hz,
3 H, aryl), 7.08-6.60 (multiplets, 26 H, aryl), 2.61 (br d, J )
13 Hz, 2 H, vinyl CH) 1.99-1.40 (overlapping multiplets, 18
H, CH2). 31P{1H} NMR (benzene-d6/CD3CN): δ -8.36 (d, J PP
) 23 Hz, 2 P), -15.69 (t, J PP ) 23 Hz, 1 P).
[ClB(CH2P P h 2)3]Ir Cl2 (13). In a flask fitted with a PTFE
stopcock, allyl 2 (0.091 g, 0.092 mmol) was dissolved in 4 mL
of benzene/CCl4 (1:1), and the resulting solution was heated
at 105 °C. Over the reaction time of 10 days, orange crystals
of 13 formed above the solvent miniscus. The crystals were
isolated by decanting the solvent and were dried in vacuo to
give 13 in 24% yield. 1H NMR (CD2Cl2): δ 7.45 (br, 12 H, ClB-
(CH2PPh2)3), 7.27 (m, 6 H, ClB(CH2PPh2)3), 7.08 (m, 12 H, ClB-
2
(CH2PPh2)3), 1.89 (br d, J HP ) 10 Hz, 6 H, PhB(CH2PPh2)3).
31P{1H} NMR (benzene-d6): δ 0.93 (s). 13C{1H} NMR (CD2-
Cl2): δ 133.3, 131.1, 128.4, 15.6 (br, PhB(CH2PPh2)3). 11B NMR
(C6D6): δ -8.7 (s). IR (KBr, cm-1): 3056 br m, 1484 m
([PhBP3]), 1434 s ([PhBP3]), 1136 m, 1091 s, 942 m, 815 m,
2
2
d8): δ 2.07 (t, 1 P, J PP(cis) ) 21 Hz), 13.12 (d, 2 P, J PP(cis) ) 21
Hz). 13C{1H} NMR (CD2Cl2): δ 133.9, 132.2, 131.8, 129.4,
129.2, 128.9, 128.5, 128.1, 127.7, 127.6, 125.6, 124.0 (aryl), 73.1
2
(d, J CP(trans) ) 9 Hz, COE CH), 34.3 (s, CH2), 33.9 (s, CH2),
26.5 (s, CH2). IR (KBr, cm-1): 3053 m, 2918 m, 2845 w, 2108
br m (IrH), 2034 br w (IrH), 1481 m ([PhBP3]), 1433 s
([PhBP3]), 1261 w, 1159 w, 1091 s, 1027 w, 926 m, 861 w, 806
741 m, 689 s, 517 s, 487 m, 442 m. Anal. Calcd for C39H36
-
BIrP3Cl3: C, 51.64; H, 4.00. Found: C, 51.47; H, 4.05. Mp:
>260 °C.

4064 Organometallics, Vol. 21, No. 20, 2002
Feldman et al.
2
Obser va tion of [Li(THF )n ]{[P h BP 3]Ir (H)2I} (14a ). Com-
pound 10 (0.020 g, 0.018 mmol) was dissolved in 0.5 mL of
benzene-d6, and LiBHEt3 (1.0 M in THF, 34 µL, 0.034 mmol)
was then added via syringe. Upon addition the purple solution
turned pale orange and a fine white precipitate formed. The
solution was filtered through glass fiber filter paper and
analyzed by NMR spectroscopy. Solvent removal in vacuo
resulted in decomposition of 14a to several species. However,
14a was characterized by derivatization: thermolysis with
PMePh2 (13 equiv, room temperature, benzene-d6, 5.5 h) gave
[PhBP3]Ir(PMePh2)H2 (5; by NMR spectroscopy). 1H NMR
(benzene-d6): δ 8.02 (q, J ) 8 Hz, 6 H, aryl), 7.65 (t, J ) 6 Hz,
5 H, aryl), 7.59 (t, J ) 7 Hz, 1 H, aryl), 7.42 (m, 6 H, aryl),
7.00 (m, 4 H, aryl), 6.89 (m, 6 H, aryl), 6.80 (t, J ) 7 Hz, 2 H),
-12.42 (dm, J HP(trans) ) 96 Hz, 3 H, IrH). 31P{1H} NMR
(benzene-d6): δ 1.40 (s). 11B NMR (C6D6): δ -12.1 (s).
[P h BP 3]Ir Me2 (16). Dropwise addition of methyllithium
(1.6 M in Et2O, 228 µL, 0.365 mmol) to a stirred solution of 10
(0.206 g, 0.182 mmol) in 20 mL of benzene resulted in a color
change from dark red to pale orange, and a colorless precipitate
formed. The solvent was removed under reduced pressure, but
the resulting solid was kept under vacuum only briefly (15
min) in order to prevent decomposition. The solid was washed
with pentane (10 mL), and compound 16 was extracted into
benzene (15 mL). This extract was concentrated to 5 mL and
layered with pentane to give 0.088 g (53%) of the product.
Complex 16 is unstable in the solid state at room temperature
and under vacuum; thus, elemental analyses were consistently
2
1
6.72 (m, 5 H, aryl), -12.11 (dm, J HP ) 111 Hz, 2 H, IrH).
off by 1-2%. H NMR (benzene-d6/THF-d8, 9:1): δ 8.06 (d, J
2
31P{1H} NMR(benzene-d6): δ 7.9 (t, J PP ) 11 Hz, 1 P), -17.7
) 7 Hz, 2 H, o-PhB(CH2PPh2)3), 7.71 (m, 12 H, PhB-
(CH2PPh2)3), 7.50 (t, J ) 7 Hz, 1 H, p-PhB(CH2PPh2)3), 7.00
(m, 18 H, PhB(CH2PPh2)3), 6.83 (m, 2 H), 2.07 (br, 6 H, PhB-
(CH2PPh2)3), 0.80 (br, 6 H, IrCH3). 31P{1H} NMR (benzene-d6/
THF-d8, 9:1): δ -25.3 (s). 13C{1H} NMR (CD2Cl2): δ 142.8,
133.9, 126.7, 126.5, 122.6 (aryl), 18.7 (br, BCH2), -3.5 (dm,
1J CP(trans) ) 92 Hz, IrCH3). 11B NMR (C6D6): δ -10.6 (s). Mp:
84-89 °C dec.
2
(d, J PP ) 11 Hz, 2 P). 11B NMR (C6D6): δ -11.8 (s).
Obser vation of [Li(THF)n]{[P h BP 3]Ir (H)2Cl} (14b). Com-
plex 14b was observed with a mixture of hydride products
(including 15) upon the addition of LiBHEt3 (1.0 M in THF,
17 µL, 0.017 mmol) to a 0.5 mL benzene-d6 solution of 11 (0.008
g, 0.009 mmol). It decomposed upon removing the solvent in
vacuo. Its 1H NMR spectrum resembles that of 14a but is
obscured by the presence of other species. Its IrH resonance
2
was observed at δ -10.12 (dm, J HP(trans) ) 125 Hz). 31P{1H}
Ack n ow led gm en t is made to the National Science
Foundation for their generous support of this work. We
thank Dr. Fred Hollander of the UC Berkeley CHEXRAY
facility for assistance with the X-ray structure deter-
minations and for solving the structure of 2.
NMR (benzene-d6): δ 9.1 (t, 2J PP ) 14 Hz, 1 P) and δ -9.2, (d,
2J PP ) 14 Hz, 2 P). 11B NMR (C6D6): δ -11.2 (s).
Obser va tion of [Li(THF )n ]{[P h BP 3]Ir H3} (15). To a 0.5
mL benzene-d6 solution of 11 (0.008 g, 0.009 mmol) was added
LiBHEt3 (1.0 M in THF, 24 µL, 0.024 mmol). Like 14a and
14b, this complex decomposed upon solvent removal. It was
characterized by derivatization by reaction with Me3SiCl (9
Su p p or tin g In for m a tion Ava ila ble: Tables of bond
distances and angles and anisotropic displacement parameters
for 2-4, 8, 10, 13, and 16. This material is available free of
charge via the Internet at http://pubs.acs.org.
50
equiv, 80 °C, 24 h), giving [PhBP3]Ir(H)3SiMe3 (by 31P{1H}
NMR spectroscopy). 1H NMR (benzene-d6): δ 8.18 (d, J ) 7
Hz, 2 H, aryl), 7.64 (m, 13 H, aryl), 7.51 (m, 6 H, aryl), 7.69 (t,
J ) 7 Hz, 2 H, aryl), 6.88 (m, 12 H, aryl), 1.89 (m, 6 H, BCH2P),
OM0205086