2-indolylphosphines, a new class of tunable ligands: Their synthesis, facile derivatization, and coordination to palladium(II)

Article abstract of DOI:10.1021/om0401004

The generation of new metal complexes with potentially interesting properties provides the motivation for designing novel polydentate bridging ligands. Herein we report the syntheses of tertiary indolylphenylphosphines L, where L = diphenyl(3-methyl-2-indolyl)-phosphine (P(C₆H ₅)₂(C₉H₈N), 1), phenylbis(3-methyl-2-indolyl)phosphine (P(C₆H₅)(C ₉H₈N)₂, 2), and bis(1H-3-indolyl)methane-(2,12)-phenylphosphine(P(C₆H ₅)(C₁₇H₁₂N₂, 3). Ligands 1-3 were functionalized at the indolyl nitrogen with a variety of both electron-withdrawing and electron-donating groups. The solid-state structures of 1, 2, and N-functionalized indolylphosphines diphenyl(3-methyl-1-benzyl-2-indolyl)phosphine (P(C₆H ₅)₂(C₉H₇N(CH₂C ₆H₅)), N-Bz-1) and bis[1-{CH₂C ₆F₅)-3-indolyl]methane-(2,12)-phenylphospnine (P(C ₆H₅)(C₁₇H₁₀N₂[CH ₂C₆F₅]₂), (N-F₅Bz) ₂-3), are reported. The reaction of ligands 1-3 with 1 equiv of Pd(COD)Cl₂ led to the formation of Pd(II) complexes of the type [Pd(L)Cl(μ-Cl)]₂ (4, L = 1; 5, L = 2; 6, L = 3). The products were characterized by ¹H, ¹³C, and ³¹P NMR spectroscopy, mass spectrometry, and elemental analysis. X-ray crystallography established the dimeric structure of the products and confirmed the ability of the ligands to serve, in the absence of base, as monodentate P-donors in reaction with a transition metal. The indolyl NH groups of the complexes 4-6 demonstrate a marked propensity for hydrogen bonding in the solid state.

Full text of DOI:10.1021/om0401004

Organometallics 2005, 24, 37-47
37
2-Indolylphosphines, a New Class of Tunable Ligands:
Their Synthesis, Facile Derivatization, and Coordination
to Palladium(II)
Joanne O. Yu, Edmond Lam, Julie L. Sereda, Nicole C. Rampersad,
Alan J. Lough, C. S. Browning,* and David H. Farrar
Davenport Chemical Research Building, University of Toronto, 80 St. George Street,
Toronto, Ontario, Canada M5S 3H6
Received July 20, 2004
The generation of new metal complexes with potentially interesting properties provides
the motivation for designing novel polydentate bridging ligands. Herein we report the
syntheses of tertiary indolylphenylphosphines L, where L ) diphenyl(3-methyl-2-indolyl)-
phosphine (P(C6H5)2(C9H8N), 1), phenylbis(3-methyl-2-indolyl)phosphine (P(C6H5)(C9H8N)2,
2), and bis(1H-3-indolyl)methane-(2,12)-phenylphosphine (P(C6H5)(C17H12N2), 3). Ligands 1-3
were functionalized at the indolyl nitrogen with a variety of both electron-withdrawing and
electron-donating groups. The solid-state structures of 1, 2, and N-functionalized indolylphos-
phines diphenyl(3-methyl-1-benzyl-2-indolyl)phosphine (P(C6H5)2(C9H7N(CH2C6H5)), N-Bz-
1) and bis[1-(CH2C6F5)-3-indolyl]methane-(2,12)-phenylphosphine (P(C6H5)(C17H10N2[CH2C6F5]2),
(N-F5Bz)2-3), are reported. The reaction of ligands 1-3 with 1 equiv of Pd(COD)Cl2 led to
the formation of Pd(II) complexes of the type [Pd(L)Cl(µ-Cl)]2 (4, L ) 1; 5, L ) 2; 6, L ) 3).
The products were characterized by 1H, 13C, and 31P NMR spectroscopy, mass spectrometry,
and elemental analysis. X-ray crystallography established the dimeric structure of the
products and confirmed the ability of the ligands to serve, in the absence of base, as
monodentate P-donors in reaction with a transition metal. The indolyl NH groups of the
complexes 4-6 demonstrate a marked propensity for hydrogen bonding in the solid state.
Introduction
Phosphines with aromatic heterocyclic substituents
are interesting ligands in coordination chemistry be-
cause they offer several potential modes of coordination
to transition metals. The most frequently studied of
these polydentate ligands are the pyridinylphosphines,
in which the pyridinyl substituents are bound to phos-
phorus at the 2-position (Figure 1). Mono-, bis-, and tris-
(2-pyridinyl)phosphines have been prepared,1,2 and their
coordination chemistry remains an area of considerable
activity,1,2 in part because of the difference in character
between the two centers of Lewis basicity. As a softer
σ-donor and stronger π-acceptor than the nitrogen
atom,2 the phosphorus center of diphenylpyridinylphos-
phine preferentially coordinates to transition metals in
obtaining mononuclear complexes.2,3
Figure 1. (a) 2-Pyridynylphosphine, a common ligand
used in coordination chemistry. (b) 2-Pyrrolylphosphine,
also used in coordination chemistry, although less fre-
quently compared to 2-pyridynylphosphine.
between the bridged metal atoms, induced by the geo-
metry and rigidity of the ligand, can yield metal-metal
interactions.2,4 These bridged complexes have received
considerable attention because of their interesting
structural features as well as their potential as cata-
lysts. Although four-membered metallacycles occasion-
ally form through P,N-chelation of the ligand, these are
observed less frequently than the above coordination
modes because of their inherent ring strain.2,3,5 In all
cases, the phosphorus center and the pyridinyl nitrogen
atoms of diphenylpyridinylphosphine serve as classic
two-electron donors in their coordination chemistry.
The bound diphenylpyridinylphosphine ligand may
bridge to an additional metal atom through the unco-
ordinated nitrogen atom to generate binuclear homo-
and heterometallic complexes.1,2,4 The small separation
* To whom correspondence should be addressed. E-mail: sbrownin@
chem.utoronto.ca.
(1) Newkome, G. R. Chem. Rev. 1993, 93, 2067.
(2) Zhang, Z.-Z.; Cheng, H. Coord. Chem. Rev. 1996, 147, 1.
(3) (a) Kuo, C. Y.; Fuh, Y. S.; Shiue, J. Y.; Yu, S. J.; Lee, G. H.;
Peng, S. M. J. Organomet. Chem. 1999, 588, 260. (b) Jones, N. D.;
MacFarlane, K. S.; Smith, M. B.; Schutte, R. P.; Rettig, S. J.; James,
B. R. Inorg. Chem. 1999, 38, 3956. (c) Nicholson, T.; Hirsch-Kuchma,
M.; Shellenbarger-Jones, A.; Davison, A.; Jones, A. Inorg. Chim. Acta
1998, 267, 319. (d) Schutte, R. P.; Rettig, S. J.; Joshi, A. M.; James, B.
R. Inorg. Chem. 1997, 36, 5809. (e) Baird, I. R.; Smith, M. B.; James,
B. R. Inorg. Chim. Acta 1995, 235, 291.
(4) Zhang, G.; Zhao, J.; Raudaschl-Sieber, G.; Herdtweck, E.; Kuhn,
F. E. Polyhedron 2002, 21, 1737.
(5) (a) Wasserman, H. J.; Moody, D. C.; Paine, R. T.; Ryan, R. R.;
Salazar, K. V. Chem. Commun. 1984, 533. (b) Arean, C. G.; Rotondo,
E.; Faraone, F. Organometallics 1991, 10, 3877. (c) Inoguchi, Y.;
Mahrla, B. M.; Neugebauer, D.; Jones, P. G.; Schimdbaur, H. Chem.
Ber. 1983, 116, 1487. (d) Olmstead, M. M.; Maisonnat, A.; Farr, J. P.;
Balch, A. L. Inorg. Chem. 1981, 20, 4060. (e) Jain, V. K.; Jakkal, V. S.;
Bohra, R. J. Organomet. Chem. 1990, 389, 417.
10.1021/om0401004 CCC: $30.25 © 2005 American Chemical Society
Publication on Web 12/08/2004

38 Organometallics, Vol. 24, No. 1, 2005
Yu et al.
Table 1. 31P NMR Signals (ppm)a and Product
Yields for N-Functionalized Ligands of 1-3
Chart 1. Novel C2-Bound Indolylphosphine
Ligands. Parent Ligands with R ) H,
Diphenyl(3-methyl-2-indolyl)phosphine
(P(C6H5)2(C9H8N), 1), Phenylbis(3-methyl-2-
indolyl)phosphine (P(C6H5)(C9H8N)2, 2), and
Bis(1H-3-indolyl)methane-(2,12)-phenylphosphine
(P(C6H5)(C17H12N2), 3)a
a Refer to Table 1 for N-functionalized indolylphosphine
ligands where R * H.
In principle, diphenyl(2-pyrrolyl)phosphine (Figure 1)
should provide a similarly rich and varied chemistry in
reaction with transition metals upon deprotonation of
its pyrrolyl nitrogen center. However, its low-yielding
synthesis6 and its propensity for complicated and un-
predictable behavior in metal coordination have ren-
dered diphenyl(2-pyrrolyl)phosphine a rarely used ligand
in reaction with transition metals.7,8
a At 25 °C in CDCl3.
reported, illustrating the ability of the ligand to serve
as a monodentate P-donor in generating dimeric coor-
dination complexes of the type [Pd(L)Cl(µ-Cl)]2.
As a phosphine substituent, the electron-rich het-
eroaromatic indole, like pyrrole, also offers further
modes of coordination through its nitrogen atom in a
potentially polydentate ligand. The required deproto-
nation of the indolyl nitrogen center provides the
opportunity to control secondary N-coordination and
yields a stronger ligand of transition metals than the
nitrogen center of pyridinylphosphines. We reasoned
that the lesser reactivity of indole relative to pyrrole,7,8
however, might permit an easier synthesis of mono- and
disubstituted indolylphenylphosphines and that these
ligands may provide a rich and interesting coordination
chemistry that is based upon their expected polyden-
ticity rather than the propensity for ligand fragmenta-
tion7 and other complications7,8 observed upon coordi-
nation of diphenyl(2-pyrrolyl)phosphine. The only report
to date of an indolylphenylphosphine involved the
synthesis of diphenyl-2,2′-biindolylphosphine and its
subsequent coordination through phosphorus to a pal-
ladium(II) center to generate a seven-membered met-
allacycle.9
This manuscript outlines the syntheses of three new
C2-bound indolylphosphines: diphenyl(3-methyl-2-in-
dolyl)phosphine (P(C6H5)2(C9H8N), 1), phenylbis(3-
methyl-2-indolyl)phosphine (P(C6H5)(C9H8N)2, 2), and
bis(1H-3-indolyl)methane-(2,12)-phenylphosphine
(P(C6H5)(C17H12N2), 3) (Chart 1). Several N-substituted
derivatives of each are also reported to demonstrate the
facility with which a variety of electron-withdrawing,
electron-donating, and chiral groups may be introduced
at the indolyl nitrogen to vary the electronic and steric
properties of the ligands (see Table 1). In addition, the
complexation of equimolar Pd(COD)Cl2 with 1-3 is
Experimental Section
General Comments. All reactions and manipulations were
carried out under an atmosphere of nitrogen using standard
Schlenk techniques unless otherwise stated. Dimethylmeth-
yleneammonium chloride, 3-methylindole, dichlorophenylphos-
phine, chlorodiphenylphosphine, 1.6 M n-butyllithium, sodium
borohydride, sodium hydride, iodomethane, benzyl bromide,
2,3,4,5,6-pentafluorobenzyl bromide, (1R)-(-)-myrtenol, and
phosphorus tribromide (Aldrich), bis(1H-3-indolyl)methane
(ChemPacific), hydrochloric acid (Fisher Scientific), and ac-
etonitrile and triethylamine (ACP Chemicals) were used
without further purification. Dichloromethane, hexanes, etha-
nol, and methanol (Caledon) were used as received. The
solvents tetrahydrofuran and diethyl ether were distilled from
dark purple solutions of sodium benzophenone ketyl under a
dinitrogen atmosphere. (1R)-(-)-Myrtenyl bromide10a and Pd-
10b
(COD)Cl2 were prepared according to literature methods.
1H, 13C{1H}, and 31P{1H} NMR spectra were recorded on
Varian XL 400 and Varian Mercury 300 spectrometers and
referenced to SiMe4 (TMS) and 85% H3PO4 in CDCl3, respec-
tively.
1-[(Dimethylamino)methyl]-3-methylindole. Dimethyl-
methyleneammonium chloride (14.05 g, 150 mmol) and 3-me-
thylindole (9.95 g, 75.9 mmol) were added to tetrahydrofuran
(300 mL). The mixture was stirred for 24 h at ambient
temperature, gradually forming a white suspension. Triethy-
lamine (21 mL, 151 mmol) was added to the mixture, and
stirring was continued for 2 h. The solvent was removed in
vacuo, affording a white residue. The residue was suspended
in water (200 mL), and the product was extracted with
dichloromethane (2 × 100 mL). The combined organic layers
were dried over anhydrous MgSO4, and the solvent was
removed in vacuo to afford the product as a cream-colored oil
(6) Arce, A. J.; Deeming, A. J.; De Sanctis, Y.; Joahl, S. K.; Martin,
C. M.; Shinhmar, M.; Speel, D. M.; Vassos, A. Chem. Commun. 1998,
1
(10.43 g, 73%). H NMR (CDCl3, δ, ppm): 7.52 (d, 1H, C8H),
233.
7.36 (d, 1H, C4H), 7.17 (t, 1H, C7H), 7.07 (t, 1H, C6H), 6.86
(s, 1H, C2H), 4.61 (s, 2H, -NCH2N-), 2.30 (s, 3H, CH3 on
indole), 2.24 (s, 6H, -N(CH3)2). 13C{1H} NMR (CDCl3, δ,
(7) Deeming, A. J.; Shinhmar, M. K. J. Organomet. Chem. 1999,
592, 235.
(8) Allen, D. W.; Charlton, J. R.; Huntley, B. G. Phosphorus 1976,
6, 191.
(9) Berens, U.; Brown, J. M.; Long, J.; Selke, R. Tetrahedron:
Asymmetry 1996, 7, 285.
(10) (a).Harwood: L. M.; Julia, M. Synthesis 1980, 6, 456-457. (b)
Drew, D.; Doyle, J. R. Inorg. Synth. 1990, 28, 348.

2-Indolylphosphines
Organometallics, Vol. 24, No. 1, 2005 39
ppm): 137.4, 129.0, 126.3, 121.8, 119.0, 118.9, 110.7, 109.9,
119.5, 111.2, and 9.9. EI-MS: m/z 368 [M+, 100], 238 [M+
-
68.6, 42.8, and 9.7. EI-MS: m/z 188 [M+, 46], 144 [M+
N(CH3)2, 42], 130 [M+ - CH2N(CH3)2, 33], 58 [CH2N(CH3)2
100].
-
3-methylindole, 80], 130 [3-methylindole+, 11]. Mp: 205-207
°C.
+
,
1,1′-Bis[(dimethylamino)methyl]bis(1H-3-indolyl)-
methane. Dimethylmethyleneammonium chloride (13.83 g,
148 mmol) and bis(1H-3-indolyl)methane (13.83 g, 56.2 mmol)
were added to tetrahydrofuran (300 mL). The mixture was
stirred for 24 h at ambient temperature, gradually forming a
pink suspension. Triethylamine (21 mL, 151 mmol) was added
to the solution, and the resultant mixture was stirred for 2 h.
The solvent was removed in vacuo, affording a pink residue.
The residue was suspended in water (200 mL) and extracted
with dichloromethane (2 × 100 mL). The combined organic
layers were dried over anhydrous MgSO4, and the solvent was
removed in vacuo to give the product as a pink oil (16.4 g, 81%).
1H NMR (CDCl3, δ, ppm): 7.45 (d, 2H, C8H), 7.24 (d, 1H, C5H),
7.02 (t, 1H, C7H), 6.90 (t, 1H, C6H), 6.73 (s, 2H, C2H), 4.43
(s, 4H, -NCH2N-), 4.07 (s, 2H, CH2 bridge), 2.07 (s, 12H,
-N(CH3)2). 13C{1H} NMR (CDCl3, δ, ppm): 137.5, 128.2, 126.8,
121.7, 119.4, 119.0, 114.6, 109.9, 68.6, 42.8, 21.2. EI-MS: m/z
360 [M+, 25], 58 [CH2N(CH3)2+, 100].
Diphenyl(3-methyl-2-indolyl)phosphine
(P(C6H5)2-
(C9H8N), 1). To a degassed solution of 1-[(dimethylamino)-
methyl]-3-methylindole (2.02 g, 10.7 mmol) in diethyl ether
(50 mL) was added 1.6 M n-BuLi (7.05 mL, 11.3 mmol)
dropwise over 10 min at ambient temperature. Upon addition
of n-BuLi, the white opaque solution became a turbid orange
solution. The solution was stirred for 4 h. The resultant
mixture was cooled to -78 °C, and chlorodiphenylphosphine
(1.94 mL, 10.7 mmol) was added dropwise over 10 min. The
beige mixture was stirred for 24 h. To quench the reaction,
methanol (2 mL) was added to the mixture. Volatile solvents
were removed in vacuo, affording P(C6H5)2(C12H15N2) as a
brown residue (3.99 g, 89%). HRMS (EI) for C24H25N2P (M+):
calcd, 372.1755; found, 372.1764. 31P{1H} NMR (CDCl3, δ,
1
ppm): -30.1. H NMR (CDCl3, δ, ppm): 7.25-7.37 (m, 14H),
4.95 (s, 2H, N-CH2), 2.09 (s, 6H, N-CH3), and 1.80 (s, 3H,
CH3 on indole). 13C{1H} NMR (CDCl3, δ, ppm): 138.9, 135.8,
132.4, 130.3, 129.2, 128.4, 128.0, 123.0, 121.3, 119.1, 110.4,
66.8, 42.1, and 10.5. EI-MS: m/z 372 [M+, 100] and 58 [Me2-
NCH2+, 100]. The brown P(C6H5)2(C12H15N2) residue was
suspended in degassed aqueous 0.1 M HCl (50 mL) and
extracted with degassed dichloromethane (2 × 100 mL). The
combined organic layers were dried over anhydrous MgSO4,
and the solvent was removed in vacuo to afford an orange
residue. The product was obtained as a white powder from
recrystallization with methanol (3.24 g, 96%). Crystals suitable
for single-crystal X-ray diffraction were obtained from slow
evaporation of the ligand in a toluene solution. Anal. Calcd
for C21H18NP (315.4): C, 80.0; H, 5.8; N, 4.4. Found: C, 80.0;
H, 5.9; N, 4.5. 31P{1H} NMR (CDCl3, δ, ppm): -33.1. 1H NMR
(CDCl3, δ, ppm): 8.21 (s, 1H, NH), 7.08-7.62 (m, 14H), 2.46
(s, 3H, CH3 on indole). 13C{1H} NMR (CDCl3, δ, ppm): 139.3,
137.4, 134.3, 129.3, 128.9, 128.8, 127.2, 123.1, 122.2, 119.4,
Bis(1H-3-indolyl)methane-(2,12)-phenylphosphine
(P(C6H5)(C17H12N2), 3). The preparation for 2 was followed,
with the exceptions of using 1,1′-bis[(dimethylamino)methyl]-
bis(1H-3-indolyl)methane (3.81 g, 10.5 mmol), 1.6 M n-BuLi
(14.0 mL, 22.4 mmol), and dichlorophenylphosphine (1.00 mL,
7.4 mmol). The aminal-protected product was recrystallized
from methanol to afford P(C6H5)(C23H26N4) as a white powder
(1.80 g, 53%). HRMS (EI) for C29H31N4P (M+): calcd, 466.2866;
found, 466.2289. 31P{1H} NMR (CDCl3, δ, ppm): -61.9. 1H
NMR (CDCl3, δ, ppm): 6.71-7.34 (m, 13H), 4.22 (d, 2H, 2JHH
2
4
) 12 Hz, N-CH2), 4.19 (dd, 1H, JHH ) 21 Hz, JPH ) 3 Hz,
CH2 bridge), 4.10 (d, 2H, 2JHH ) 12 Hz, N-CH2), 4.04 (dd, 1H,
2JHH ) 21 Hz, JPH ) 3 Hz, CH2 bridge), and 1.63 (s, 12H,
4
N-CH3). 13C{1H} NMR (CDCl3, δ, ppm): 139.5, 138.1, 134.3,
131.5, 129.2, 128.7, 128.1, 127.7, 122.6, 119.4, 118.6, 116.8,
110.4, 67.4, 42.1, and 21.4. EI-MS: m/z 466 [M+, 21], 408 [M+
- Me2NCH2, 6], and 58 [Me2NCH2+, 100]. The deprotection of
the aminal product, P(C6H5)(C23H26N4), was achieved in the
similar fashion as 2, with the exceptions of using P(C6H5)-
(C23H26N4) (1.50 g, 3.2 mmol) and NaBH4 (0.50 g, 13.2 mmol),
to afford the product as a white powder (0.99 g, 87%). Anal.
Calcd for C12H16N2 (352.4): C, 78.4; H, 4.9; N, 8.0. Found: C,
78.4; H, 5.2; N, 7.9. 31P{1H} NMR (CDCl3, δ, ppm): -56.0. 1H
NMR (CDCl3, δ, ppm): 8.13 (s, 2H, NH, br), 7.27-7.76 (m,
119.3, 111.0, and 9.9. EI-MS: m/z 315 [M+, 100], 238 [M+
-
Ph, 27], 130 [(3-methylindole)+, 7], 77 [Ph+, 8]. Mp: 147-148
°C.
Phenylbis(3-methyl-2-indolyl)phosphine
(P(C6H5)-
(C9H8N)2, 2). The preparation for 1 was followed, with the
exceptions of using 1-[(dimethylamino)methyl]-3-methylindole
(3.74 g, 19.9 mmol), 1.6 M n-BuLi (13.0 mL, 20.8 mmol), and
dichlorophenylphosphine (1.00 mL, 7.4 mmol). The aminal-
protected product was recrystallized from methanol to afford
P(C6H5)(C24H30N4)2 as a white powder (1.39 g, 51%). HRMS
(EI) for C30H35N4P (M+): calcd, 482.2599; found, 482.2589. 31P-
{1H} NMR (CDCl3, δ, ppm): -65.1. 1H NMR (CDCl3, δ, ppm):
7.05-7.65 (m, 13H), 4.25 (d, 2H, 2JHH ) 13 Hz, N-CH2), 4.15
2
4
13H), 4.57 (dd, 1H, JHH ) 21 Hz, JPH ) 3 Hz, CH2 bridge),
4.41 (dd, 1H, 2JHH ) 21 Hz, 4JPH ) 3 Hz, CH2 bridge). 13C{1H}
NMR (CDCl3, δ, ppm): 138.3, 137.0, 133.6, 131.7, 130.9, 128.8,
128.5, 123.0, 119.7, 118.8, 116.8, 111.0, 21.1. EI-MS: m/z 352
[M+, 77], 275 [M+ - Ph, 41]. Mp: 204-205 °C.
2
Representative N-Substitution in Diphenyl(1,3-meth-
yl-2-indolyl)phosphine (P(C6H5)2(C19H8N)): Reaction with
Iodomethane. P(C6H5)2(C9H8N) (1; 0.30 g, 0.95 mmol) and
NaH (0.028 g, 1.17 mmol) were added to a Schlenk vessel
charged with nitrogen. Anhydrous tetrahydrofuran (10 mL)
was added via syringe, and the colorless solution was stirred
for 1 h at ambient temperature. Iodomethane (0.065 mL, 1.04
mmol) was added, and the resulting solution immediately
turned yellow. The solution was stirred for 2 h at ambient
temperature. Volatile solvents were removed in vacuo, afford-
ing a yellow residue. The product was purified by column
chromatography with an eluant of hexanes/dichloromethane
(2:1), affording the product as a white powder (0.15 g, 48%).
Diphenyl(1,3-methyl-2-indolyl)phosphine (P(C6H5)2-
(C10H10N), (N-Me)-1). Anal. Calcd for C22H20NP (329.1): C,
80.22; H, 6.12; N, 4.25. Found: C, 80.29; H, 6.22; N, 4.27. 31P-
{1H} NMR (CDCl3, δ, ppm): -33.1. 1H NMR (CDCl3, δ, ppm):
7.18-7.70 (m, 14H), 3.58 (s, 3H, N-CH3), and 2.32 (s, 3H, CH3
on indole). 13C{1H} NMR (CDCl3, δ, ppm): 139.4, 135.5, 132.1,
128.9, 128.6, 128.4, 128.1, 123.2, 123.0, 119.4, 118.9, 109.4,
32.0, and 10.6. EI-MS: m/z 329 [M+, 100].
(d, 2H, JHH ) 13 z, N-CH2), 2.63 (s, 6H, N-CH3), 2.58 (s,
6H, N-CH3), and 2.16 (s, 6H, CH3 on indole). 13C{1H} NMR
(CDCl3, δ, ppm): 140.5, 139.0, 137.0, 130.8, 128.7, 128.1, 127.6,
126.8, 125.3, 123.8, 122.8, 122.7, 119.6, 119.6, 118.5, 111.2,
109.4, 65.2, 41.9, 10.9 and 9.9. EI-MS: m/z 482 [M+, 1], 425
[M+ - Me2NCH2, 32], and 58 [Me2NCH2+, 100]. In a Schlenk
vessel, the aminal-protected product, P(C6H5)(C24H30N4)2 (0.77
g, 1.6 mmol), and NaBH4 (0.124 g, 3.3 mmol) were dissolved
in a degassed ethanol-tetrahydrofuran solution (50 mL, 1:1
v/v). The solution was refluxed for 5 h at 85 °C. The solvent
was removed in vacuo, affording a light yellow residue. The
residue was suspended in degassed diluted HCl (100 mL) and
extracted with degassed dichloromethane (2 × 100 mL). The
combined organic layers were dried over anhydrous MgSO4,
and the solvent was removed in vacuo to give the product as
a white powder (0.42 g, 71%). Anal. Calcd for C24H21N2P‚H2O
(386.43): C, 74.6; H, 6.0; N, 7.3. Found: C, 74.5; H, 5.7; N,
1
7.3. 31P{1H} NMR (CDCl3, δ, ppm): -59.3. H NMR (CDCl3,
δ, ppm): 8.20 (s, 2H, NH, br), 7.20-7.33 (m, 13H), 2.43 (s,
6H, CH3 on indole). 13C{1H} NMR (CDCl3, δ, ppm): 138.3,
135.2, 132.1, 129.6, 129.1, 128.9, 126.2, 123.3, 122.0, 119.7,

40 Organometallics, Vol. 24, No. 1, 2005
Yu et al.
Diphenyl(1-benzyl-3-methyl-2-indolyl)phosphine
(P(C6H5)2(C16H14N), (N-Bz)-1). The preparation for (N-Me)-1
was followed. (N-Bz)-1 was obtained as a white powder (0.20
g, 52%). Crystals suitable for single-crystal X-ray diffraction
were obtained from slow evaporation of the ligand in a
hexane-dichloromethane solution. Anal. Calcd for C22H20NP
(405.2): C, 82.94; H, 5.97; N, 3.45. Found: C, 83.04; H, 6.04;
N, 3.45. 31P{1H} NMR (CDCl3, δ, ppm): -32.0. 1H NMR (CDCl3,
δ, ppm): 6.83-7.62 (m, 19H), 5.61 (d, 2H, 4JPH ) 3 Hz, CH2-
N), and 2.26 (s, 3H, CH3 on indole). 13C{1H} NMR (CDCl3, δ,
ppm): 138.8, 137.8, 134.8, 132.3, 129.1, 129.0, 128.5, 128.4,
128.3, 128.2, 126.3, 126.1, 123.3, 121.9, 119.3, 110.3, 48.4, and
10.7. EI-MS: m/z 405 [M+, 100], 328 [M+ - Ph, 8], and 314
[M+ - CH2C6H5, 24].
Diphenyl[1-(2,3,4,5,6-pentafluorobenzyl)-3-methyl-2-
indolyl]phosphine (P(C6H5)2(C16H9F5N), (N-F5Bz)-1). The
preparation for (N-Me)-1 was followed. (N-F5Bz)-1 was
obtained as a white powder (0.26 g, 56%). HRMS (EI) for
C28H19F5NP (M+): calcd, 495.1175; found, 495.1182. 31P{1H}
NMR (CDCl3, δ, ppm): -30.8 (t, 6JPFo ) 25 Hz). 19F{1H} NMR
Phenylbis[1-(2,3,4,5,6-pentafluorobenzyl)-3-methyl-2-
indolyl]phosphine (P(C6H5)(C16H9F5N)2, (N-F5Bz)2-2). The
preparation for (N-Me)2-2 was followed. (N-F5Bz)2-2 was
obtained as a white powder (0.19 g, 32%). HRMS (EI) for
C38H23F10N2P (M+): calcd, 728.1439; found, 728.1428. 31P{1H}
NMR (CDCl3, δ, ppm): -52.3 (quintet, 6JPFo ) 20 Hz). 19F{1H}
NMR (CDCl3, δ, ppm): -142.3 (ddd, 6JPFo ) 28 Hz, 3JFoFm(cis)
)
22 Hz, 5JFoFm(trans) ) 8 Hz, 4F, o-F), -154.6 (t, 3JFpFm ) 21 Hz,
3
3
2F, p-F), and -162.3 (ddd, JFmFo(cis) ) 22 Hz, JFmFp) 21 Hz,
5JFmFo(trans) ) 8 Hz, 4F, m-F). 1H NMR (CDCl3, δ, ppm): 7.17-
2
7.54 (m, 13H), 5.75 (d, 2H, JHH ) 17 Hz, N-CH2), 5.65 (d,
2
2H, JHH ) 17 Hz, N-CH2), and 1.82 (s, 6H, CH3 on indole).
13C{1H} NMR (CDCl3, δ, ppm): 146.2, 143.8, 141.4, 139.5,
138.2, 135.8, 132.6, 131.4, 128.9, 128.8, 128.5, 125.1, 123.7,
122.3, 119.7, 118.9, 111.0, 109.0, 37.1, and 9.3. EI-MS: m/z
728 [M+, 100], 547 [M+ - CH2C6F5, 8], and 181 [CH2C6F5
21].
,
+
Phenylbis(1-(R)-(-)-myrtenyl-3-methyl-2-indolyl)phos-
phine (P(C6H5)(C19H22N)2, (N-(R)-(-)myrtenyl)2-2). The
preparation for (N-Me)2-2 was followed. (N-(R)-(-)myrte-
nyl)2-2 was obtained as a white powder (0.21 g, 40%). HRMS
(EI) for C44H29N2P (M+): calcd, 636.3633; found, 636.3641. 31P-
{1H} NMR (CDCl3, δ, ppm): -55.2. 1H NMR (CDCl3, δ, ppm):
6.89-7.47 (m, 13H), 4.87 (d, 2H, 2JHH ) 17 Hz, N-CH2), 4.75
6
3
(CDCl3, δ, ppm): -141.6 (ddd, JPFo ) 31 Hz, JFoFm(cis) ) 23
Hz, 5JFoFm(trans) ) 8 Hz, 2F, o-F), -154.2 (t, 3JFpFm ) 21 Hz, 1F,
3
3
p-F), and -161.1 (ddd, JFmFo(cis) ) 23 Hz, JFmFp) 21 Hz,
5JFmFo(trans) ) 8 Hz, 2F, m-F). 1H NMR (CDCl3, δ, ppm): 7.13-
7.53 (m, 14H), 5.75 (s, 2H, CH2-N), and 2.80 (s, 3H, CH3 on
indole). 13C{1H} NMR (CDCl3, δ, ppm): 146.6, 143.9, 141.7,
139.2, 138.7, 138.5, 136.0, 134.2, 132.3, 129.2, 129.1, 128.5,
128.4, 123.6, 122.4, 119.5, 111.6, 109.2, 37.6, and 10.4. EI-
2
(d, 2H, JHH ) 17 Hz, N-CH2), 4.66 (s, 2H, alkene CH on
myrtenyl), 2.37 (m, 2H, CH on myrtenyl), 2.24 (s, 4H, CH2
bridge on myrtenyl), 2.19 (s, 2H, CH on myrtenyl), 1.84 (s, 6H,
CH3 on indole), 0.99 (s, 6H, CH3 on myrtenyl), 0.90 (d, 4H,
3JHH ) 7 Hz, CH2 on myrtenyl), and 0.59 (s, 6H, CH3 on
myrtenyl). 13C{1H} NMR (CDCl3, δ, ppm): 144.3, 138.9, 135.8,
132.9, 130.0, 129.0, 128.6, 128.3, 123.3, 122.7, 118.9, 118.8,
117.8, 110.3, 49.1, 43.4, 40.4, 38.1, 31.4, 30.8, 26.1, 20.9, and
MS: m/z 495 [M+, 100], 418 [M+ - Ph, 54], 314 [M+
-
CH2C6F5, 20], and 181 [CH2C6F5+, 28].
Diphenyl(1-(R)-(-)-myrtenyl-3-methyl-2-indolyl)phos-
phine (P(C6H5)2(C19H22N), (N-(R)-(-)-myrtenyl)-1). The
preparation for (N-Me)-1 was followed. (N-(R)-(-)-myrte-
nyl)-1 was obtained as a white powder (0.18 g, 42%). HRMS
(EI) for C31H32NP (M+): calcd, 449.2272. found, 449.2278. 31P-
{1H} NMR (CDCl3, δ, ppm): -31.9. 1H NMR (CDCl3, δ, ppm):
6.96-7.58 (m, 14H), 5.01 (d, 1H, 2JHH ) 17 Hz, N-CH2), 4.89
10.1. EI-MS: m/z 636 [M+, 44], 621 [M+ - Me, 18], 559 [M+
-
Ph, 6], 501 [M+ - myrtenyl, 23], and 264 [1-myrtenyl-3-
methylindole, 25].
Bis(1-methyl-3-indolyl)methane-(2,12)-phenylphos-
phine (P(C6H5)(C19H16N2), (N-Me)2-3). The preparation for
(N-Me)-1 was followed, with the exception of using P(C6H5)-
(C17H12N2) (3; 0.30 g, 0.85 mmol), NaH (0.049 g, 1.18 mmol),
and iodomethane (0.12 mL, 1.93 mmol). (N-Me)2-3 was
obtained as a white powder (0.27 g, 82%). Crystals suitable
for X-ray diffraction were obtained by slow evaporation of the
ligand from a hexane-dichloromethane solution. HRMS (EI)
for C25H21N2P (M+): calcd, 380.1442; found, 380.1437. 31P{1H}
NMR (CDCl3, δ, ppm): -64.4. 1H NMR (CDCl3, δ, ppm): 7.17-
2
(d, 1H, JHH ) 17 Hz, N-CH2), 4.51 (s, 1H, alkene CH on
myrtenyl), 2.31 (s, 2H, CH2 bridge on myrtenyl), 2.26 (s, 1H,
CH on myrtenyl), 2.20 (m, 1H, CH on myrtenyl), 1.88 (s, 3H,
CH3 on indole), 1.14 (s, 3H, CH3 on myrtenyl), 0.96 (d, 2H,
3JHH ) 6 Hz, CH2 on myrtenyl), and 0.70 (s, 3H, CH3 on
myrtenyl). 13C{1H} NMR (CDCl3, δ, ppm): 144.4, 138.6, 135.3,
132.6, 132.4, 128.8, 128.4, 128.3, 128.1, 122.8, 119.0, 117.0,
110.4, 109.4, 49.0, 43.5, 40.8, 38.2, 31.4, 30.8, 26.1, 21.0, and
10.6. EI-MS: m/z 449 [M+, 100] and 434 [M+ - Me, 15].
Phenylbis(1,3-dimethyl-2-indolyl)phosphine (P(C6H5)-
(C10H10N)2, (N-Me)2-2). The preparation for (N-Me)-1 was
followed, with the exception of using P(C6H5)(C9H8N)2 (2; 0.30
g, 0.82 mmol), NaH (0.047 g, 1.96 mmol), and iodomethane
(0.11 mL, 1.77 mmol). (N-Me)2-2 was obtained as a white
product (0.15 g, 38%). HRMS (EI) for C26H25N2P (M+): calcd,
396.1755; found, 396.1752. 31P{1H} NMR (CDCl3, δ, ppm):
-53.3. 1H NMR (CDCl3, δ, ppm): 7.10-7.56 (m, 13H), 3.65 (s,
6H, CH3-N), and 2.04 (s, 6H, CH3 on indole). 13C{1H} NMR
(CDCl3, δ, ppm): 139.3, 134.2, 132.5, 130.9, 128.8, 128.7, 128.4,
126.7, 122.9, 120.6, 119.0, 109.1, 123.3, 31.5, and 9.9. EI-MS:
m/z 396 [M+, 100], 381 [M+ - CH3, 6], 252 [M+ - (1,3-
methylindole), 13], and 144 [(1,3-methylindole)+, 17].
2
4
7.79 (m, 13H), 4.64 (dd, 1H, JHH ) 21 Hz, JPH ) 4 Hz, CH2
bridge), 4.48 (dd, 1H, 2JHH ) 21 Hz, 4JPH ) 4 Hz, CH2 bridge),
and 3.72 (s, 6H, CH3 on indole). 13C{1H} NMR (CDCl3, δ,
ppm): 139.6, 136.1, 134.3, 130.0, 129.8, 128.8, 127.1, 122.4,
119.1, 118.8, 115.7, 109.0, 31.0, and 21.5. EI-MS: m/z 380 [M+,
100], 365 [M+ - Me, 8], 303 [M+ - Ph, 31].
Bis(1-benzyl-3-indolyl)methane-(2,12)-phenylphos-
phine (P(C6H5)(C31H24N2), (N-Bz)2-3). The preparation for
(N-Me)2-3 was followed. (N-Bz)2-3 was obtained as a white
powder (0.38 g, 84%). HRMS (EI) for C37H29N2P (M+): calcd,
532.2068; found, 532.2070. 31P{1H} NMR (CDCl3, δ, ppm):
-66.3. 1H NMR (CDCl3, δ, ppm): 6.78-7.84 (m, 23H), 5.50
2
2
(d, 2H, JHH ) 17 Hz, N-CH2), 5.35 (d, 2H, JHH ) 17 Hz,
N-CH2), 4.74 (dd, 1H, 2JHH ) 21 Hz, 4JPH ) 3 Hz, CH2 bridge),
2
4
and 4.60 (dd, 1H, JHH ) 21 Hz, JPH ) 3 Hz, CH2 bridge).
13C{1H} NMR (CDCl3, δ, ppm): 142.7, 139.3, 137.4, 134.3,
130.3, 128.5, 128.4, 127.7, 127.0, 126.2, 122.7, 119.5, 118.9,
Phenylbis(1-benzyl-3-methyl-2-indolyl)phosphine
(P(C6H5)(C16H14N)2). The preparation for (N-Me)2-2 was
followed. (N-Bz)2-2 was obtained as a white powder (0.19 g,
46%). HRMS (EI) for C38H33N2P (M+): calcd, 548.2381; found,
548.2370. 31P{1H} NMR (CDCl3, δ, ppm): -53.6. 1H NMR
116.3, 110.0, 48.4, and 22.7. EI-MS: m/z 532 [M+, 89], 455
[M+ - Ph, 8], 441 [M+ - CH2C6H5, 81], and 91 [CH2C6H5
,
+
2
100].
(CDCl3, δ, ppm): 6.65-7.46 (m, 23H), 5.37 (d, 2H, JHH ) 17
Hz, N-CH2), 5.28 (d, 2H, 2JHH ) 17 Hz, N-CH2), and 1.89 (s,
6H, CH3 on indole). 13C{1H} NMR (CDCl3, δ, ppm): 138.8,
137.9, 133.0, 132.6, 129.3, 128.6, 128.4, 128.1, 126.7, 126.5,
126.0, 123.0, 121.1, 119.1, 118.9, 109.9, 48.1, and 10.1. EI-
MS: m/z 548 [M+, 9], 457 [M+ - Benz, 7], 220 [1-benzyl-3-
methylindole+, 8] and 91 [benzyl+, 100].
Bis[1-(2,3,4,5,6-pentafluorobenzyl)-3-indolyl]methane-
(2,12)-phenylphosphine (P(C6H5)(C31H14F10N2), (N-F5Bz)2-
3). The preparation for (N-Me)2-3 was followed. (N-F5Bz)2-3
was obtained as a white powder (0.56 g, 92%). Crystals suitable
for single-crystal X-ray diffraction were obtained from slow
evaporation of the ligand in a CDCl3 solution. HRMS (EI) for

2-Indolylphosphines
Organometallics, Vol. 24, No. 1, 2005 41
Table 2. Crystallographic Data of Ligands 1 and 2 and of the N-Functionalized Ligands (N-Bz)-1,
(N-CH2NMe2)2-3, and (N-F5Bz)2-3
1
2
(N-Bz)-1
(N-CH2NMe2)2-3
(N-F5Bz)2-3
formula
formula wt
cryst color, shape
cryst size, mm
cryst syst
space group
a, Å
C
21H18NP
C24H21N2P
368.40
C28H24NP
C29H31N4P
466.55
C37H19F10N2P‚CHCl3
831.88
315.33
405.45
colorless, block
colorless, block
colorless, block
colorless, plate
colorless, block
0.35 × 0.30 × 0.30 0.20 × 0.18 × 0.18 0.46 × 0.30 × 0.22 0.30 × 0.25 × 0.12 0.32 × 0.30 × 0.22
triclinic
P1h
monoclinic
P21/c
10.3563(3)
10.3027(6)
19.0016(8)
90
monoclinic
P21/c
13.7780(5)
8.7875(4)
18.6350(7)
90
monoclinic
P21/c
12.8780(3)
18.6590(6)
11.6680(3)
90
monoclinic
P21/n
16.5993(5)
12.00343(3)
17.1393(4)
90
9.9678(2)
10.3453(2)
17.4704(4)
79.973(8)
75.992(7)
74.133(9)
1670.09(6)
4
b, Å
c, Å
R, deg
â, deg
104.383(3)
90
105.301(2)
90
116.2791(18)
90
98.811(2)
90
γ, deg
V, Å3
1963.9(2)
4
2176.2(2)
4
2513.94(12)
4
3374.7(2)
4
Z
Dcalcd, g cm-3
F(000)
1.254
1.246
1.237
1.233
1.637
664
776
856
992
1672
µ, mm-1
λ(Mo KR), Å
limiting indices
0.163
0.150
0.141
0.134
0.409
0.710 73
0 e h e 12
-12 e k e 13
-21 e l e 22
2.55-27.48
0.710 73
-13 e h e 13
-13 e k e 13
-24 e l e 24
2.27-27.50
0.710 73
-17 e h e 17
-10 e k e 11
-23 e l e 24
2.38-27.50
0.971 and 0.909
19 191
0.710 73
-15 e h e 13
-22 e k e 22
-13 e l e 13
2.93-25.04
0.710 73
-21 e h e 21
-15 e k e 15
-22 e l e 22
1.59-27.53
2θ range, deg
max and min transmission 0.9526 and 0.9450 0.993 and 0.602
0.9841 and 0.9609 0.964 and 0.852
17 602
4431/0.065
0.0064(12)
312
no. of rflens collected
no. of indep rflns/Rint
extinction coeff
no. of refined params
final R1, wR2
22 759
16 135
32 929
7596/0.046
0.0014(16)
426
4736/0.0904
0.0111(16)
255
5299/0.0466
0.0073(17)
273
8134/0.0528
0.0013(4)
488
0.0449, 0.1140
0.0767, 0.1320
1.029
0.0546, 0.1221
0.1017, 0.1442
1.020
0.0520, 0.1298
0.0866, 0.1529
1.029
0.0473, 0.1095
0.0725, 0.1237
1.019
0.0438, 0.1071
0.0721, 0.1221
1.027
final R1, wR2 (all data)
goodness of fit
∆Fmin, ∆Fmax, e Å-3
-0.258, 0.257
-0.318, 0.359
-0.391, 0.346
-0.229, 0.580
-0.494, 0.367
C37H19F10N2P (M+): calcd, 712.1126; found, 712.1124. 31P{1H}
NMR (CDCl3, δ, ppm): -67.3 (quintet, 6JPFo ) 27 Hz). 19F{1H}
red powder. The powder was recrystallized from a dichlo-
romethane-hexanes mixture (3:1 v/v) at ambient temperature
to give red plates suitable for single-crystal X-ray diffraction
(0.0303 g, 88%). Anal. Calcd for C42H36Cl4N2P2Pd2 (985.35): C,
51.20; H, 3.68; N, 2.84. Found: C, 50.91; H, 4.01; N, 2.67. 31P-
NMR (CDCl3, δ, ppm): -141.4 (ddd, 6JPFo ) 27 Hz, 3JFoFm(cis)
)
22 Hz, 5JFoFm(trans) ) 8 Hz, 4F, o-F), -154.4 (t, 3JFpFm ) 21 Hz,
3
3
2F, p-F), and -161.8 (ddd, JFmFo(cis) ) 22 Hz, JFmFp) 21 Hz,
5JFmFo(trans) ) 8 Hz, 4F, m-F). 1H NMR (CDCl3, δ, ppm): 6.96-
{1H} NMR (CDCl3, δ, ppm): 14.6. H NMR (CDCl3, δ, ppm):
1
2
7.78 (m, 14H), 5.50 (d, 2H, JHH ) 18 Hz, CH2-N), 5.45 (d,
10.2 (s, 2H, NH), 7.14-7.66 (m, 28H), 1.68 (s, 6H, CH3 on
indole).
2
2
4
2H, JHH ) 18 Hz, CH2-N), 4.59 (dd, 1H, JHH ) 20 Hz, JPH
1
4
) 4 Hz, CH2 bridge), and 4.50 (dd, 1H, JHH ) 20 Hz, JPH
)
[PdP(C6H5)(C9H8N)2Cl(µ-Cl)]2 (5). The preparation for 4
was followed with the exceptions of using 2 (0.022 g, 0.070
mmol) and Pd(COD)Cl2 (0.024 g, 0.065 mmol). The resultant
powder after filtration was recrystallized from a dichlo-
romethane-diethyl ether mixture (3:1 v/v) at ambient tem-
perature to afford red blocks suitable for single-crystal X-ray
diffraction (0.0338 g, 95%). Anal. Calcd for C48H42Cl4N4P2Pd2‚
4H2O (1163.53): C, 49.62; H, 4.21; N, 4.83. Found: C, 49.70;
H, 4.07; N, 4.42. 31P{1H} NMR (CDCl3, δ, ppm): -5.7. 1H NMR
(CDCl3, δ, ppm): 9.06 (s, 2H, NH), 7.16-7.62 (m, 26H), 2.00
(s, 12H, CH3 on indole).
4 Hz, CH2 bridge). 13C{1H} NMR (CDCl3, δ, ppm): 146.6, 144.0,
142.0, 139.6, 139.3, 138.7, 136.0, 133.2, 129.7, 129.6, 128.7,
127.4, 123.3, 119.9, 119.2, 118.0, 110.7, 109.2, 37.3, and 21.6.
EI-MS: m/z 712 [M+, 89], 635 [M+ - Ph, 6], 531 [M+
CH2C6F5, 100], 453 [M+ - CH2C6F5 - Ph], 350 [M+
-
-
2(CH2C6F5), 40], 273 [M+ - 2(CH2C6F5) - Ph, 33], and 181
[CH2C6F5+, 16].
Bis(1-(R)-(-)-myrtenyl-3-indolyl)methane-(2,12)-phe-
nylphosphine (P(C6H5)(C37H40N2), (N-(R)-(-)-myrtenyl)2-
3). The preparation for (N-Me)2-3 was followed. (N-(R)-(-)-
myrtenyl)2-3 was obtained as a yellow powder (0.43 g, 81%).
HRMS (EI) for C43H45N2P (M+): calcd, 620.3320; found,
660.3332. 31P{1H} NMR (CDCl3, δ, ppm): -66.8. 1H NMR
(CDCl3, δ, ppm): 7.07-7.80 (m, 13H), 4.96 (s, 2H, alkene CH
[PdP(C6H5)(C17H12N2)Cl(µ-Cl)]2 (6). The preparation
for 4 was followed with the exceptions of using 3 (0.028 mg,
0.089 mmol) and Pd(COD)Cl2 (26.0 mg, 0.074 mmol). The
resultant powder after filtration was recrystallized from
dichloromethane-hexanes (3:1 v/v) at ambient temperature
to give red blocks suitable for single-crystal X-ray diffraction
(0.0352 g, 90%). Anal. Calcd for C46H34Cl4N4P2Pd2‚2H2O
(1095.42): C, 50.41; H, 3.23; N, 5.29. Found: C, 50.28; H, 3.26;
N, 5.04. 31P{1H} NMR (CDCl3, δ, ppm): -14.9. 1H NMR (CDCl3,
δ, ppm): 9.76 (s, 2H, NH, br), 7.16-7.62 (m, 26H), 4.42 (dd,
1H, 2JHH ) 21 Hz, 4JPH ) 4 Hz, CH2 bridge), and 4.34 (dd, 1H,
2
on myrtenyl), 4.69 (d, 2H, JHH ) 18 Hz, N-CH2), 4.66 (dd,
1H, 2JHH ) 21 Hz, 4JPH ) 3 Hz, CH2 bridge), 4.55 (d, 2H, 2JHH
2
4
) 18 Hz, N-CH2), 4.53 (dd, 1H, JHH ) 21 Hz, JPH ) 3 Hz,
CH2 bridge), 2.32 (s, 4H, CH2 bridge on myrtenyl), 2.27 (s, 2H,
CH on myrtenyl), 2.18 (m, 2H, CH on myrtenyl), 1.15 (d, 4H,
3JHH ) 5 Hz, CH2 on myrtenyl), 0.81 (s, 6H, CH3 on myrtenyl),
and 0.72 (s, 6H, CH3 on myrtenyl). 13C{1H} NMR (CDCl3, δ,
ppm): 142.9, 139.5, 137.2, 134.7, 130.8, 129.7, 128.6, 127.5,
122.4, 119.1, 118.7, 118.1, 116.0, 110.4, 49.4, 43.3, 40.9, 38.3,
31.6, 31.0, 26.2, 21.7, and 21.1. EI-MS: m/z 620 [M+, 81], 486
[M+ - myrtenyl, 12], and 351 [M+ - 2(myrtenyl), 9].
4
2JHH ) 21 Hz, JPH ) 4 Hz, CH2 bridge).
X-ray Crystallography. Details about data collection and
solution refinement are given in Tables 2 and 3. X-ray data
were collected on a Nonius Kappa CCD diffractometer using
graphite-monochromated Mo KR radiation (λ ) 0.710 73 Å).
A combination of 1° φ and ω (with κ offsets) scans were used
to collect sufficient data. The data frames were integrated and
scaled using the Denzo-SMN package. The structures were
solved and refined with the SHELXTL-PC v5.1 software
[PdP(C6H5)2(C9H8N)Cl(µ-Cl)]2, (4). A solution of 1 (0.022
g, 0.070 mmol) in acetonitrile (5 mL) was added dropwise to a
solution of Pd(COD)Cl2 (0.022 g, 0.070 mmol) in acetonitrile.
The resulting orange mixture was stirred at room temperature
for 15 min. The solvent was removed in vacuo, affording a

42 Organometallics, Vol. 24, No. 1, 2005
Table 3. Crystallographic Data of Complexes 4-6
Yu et al.
4
5
6
formula
formula wt
cryst color, shape
cryst size, mm
cryst syst
space group
a, Å
C
42H36Cl4N2P2Pd
C24H21Cl2N2PPd
545.70
red-orange, needle
0.08 × 0.05 × 0.04
monoclinic
P21/c
8.2002(4)
19.310(1)
14.4641(9)
90
100.594(2)
90
C46H34N4O2P2Pd2Cl4‚H2O‚CH2Cl2
1265.20
red-orange, plate
0.32 × 0.18 × 0.02
triclinic
P1h
8.7188(2)
11.8646(4)
12.2122(3)
79.43(1)
985.27
red-orange, plate
0.56 × 0.30 × 0.02
monoclinic
P21/c
15.6092(5)
8.0167(2)
15.9823(4)
90
b, Å
c, Å
R, deg
â, deg
96.823(1)
90
79.39(1)
87.59(1)
γ, deg
V, Å3
1985.77(9)
2
2251.2(2)
4
1220.56(6)
1
Z
Dcalcd, g cm-3
F(000)
1.648
1.610
1.721
984
1096
632
µ, mm-1
λ(Mo KR), Å
limiting indices
1.289
1.147
1.285
0.710 73
0.710 73
0.710 73
-20 e h e 20
-8 e k e 10
-19 e l e 20
1.02- 27.48
0.9747 and 0.5322
14 479
-10 e h e 10
-25 e k e 25
-18 e l e 18
1.02-27.48
0.9556 and 0.9138
19 038
-11 e h e 11
-15 e k e 15
-15 e l e 15
1.02-27.48
0.9748 and 0.6839
19 119
2θ range, deg
max and min transmission
no. of rflens collected
no. of indep rflns/Rint
extinction coeff
4839/0.0501
0.0021(5)
241
5317/0.1572
0.0138(9)
274
5618/0.0635
0.0043(9)
315
no. of refined params
final R1, wR2
0.0320, 0.825
0.0407, 0.0878
1.035
0.0625, 0.1260
0.1546, 0.1721
0.985
0.0387, 0.0943
0.0510, 0.1019
1.050
final R1, wR2 (all data)
goodness of fit
∆Fmin, ∆Fmax, e Å-3
-1.066, 0.676
-1.056, 1.167
-1.367, 0.887
package. Refinement was by full-matrix least squares on F2
using data (including negative intensities). Absorption correc-
tions were made for every structure. Hydrogen atoms were
introduced at calculated positions and treated as riding atoms,
included in structure factor calculations, and not refined. All
the heavy atoms were refined anisotropically.
aminal-protected groups from the product required the
use of NaBH4 in a refluxing 1:1 ethanol-tetrahydrofu-
ran mixture over 5 h. Removal of the volatile solvents,
followed by acidic aqueous workup and subsequent
recrystallization from methanol, afforded 3 in good
yields.
The 31P NMR spectra of 1 and 2 both indicated the
presence of a single phosphorus environment; the ad-
ditional indolyl substituent of 2 results in the upfield
shift of its 31P NMR signal (δ -59.3 ppm) relative to
Results and Discussion
Syntheses and Characterizations of Ligands
1-3. Ligands 1-3 were synthesized by modifying the
method of Katritzky and co-workers,11 in which substi-
tution at the phosphorus atom proceeds via a C2-
lithiated indole intermediate. Lithiation of indole occurs
preferentially at the nitrogen and subsequently at the
C3 position of the ring.11 By introducing a methyl group
at the C3 position and an ortho metal-directing aminal
protecting group on the nitrogen, lithiation of 1-[(dim-
ethylamino)methyl]-3-methylindole occurs was achieved
at the C2 position. The addition of the appropriate
chlorophenylphosphine leads to chloride substitution by
the indolyl groups to provide 1 and 2. While removal of
the aminal protecting group took place during the acidic
aqueous workup of phosphine 1, reaction with NaBH4
in a refluxing 1:1 ethanol-tetrahydrofuran mixture was
required to displace the aminal protecting group from
2. Subsequent recrystallization from methanol afforded
1 and 2 in good yields. The preparation of ligand 3 was
achieved in a similar manner. Lithiation at the C2
position of 1,1′-bis[(dimethylamino)methyl]bis(1H-3-in-
dolyl)methane followed by the addition of dichlorophe-
nylphosphine at -78 °C replaced the chlorides of the
phosphine ligand with the coupled indolyl substituent.
As observed in the synthesis of 2, displacement of the
1
the monoindolyl substituted 1 (δ -33.1 ppm). The H
and 13C NMR spectra of 1 and 2 confirmed the presence
of one and two methylindolyl substituents respectively
bound to phosphorus, as well as the removal of the
aminal protecting groups from the indolyl nitrogen
atoms. The small difference in 31P NMR chemical shift
of 3 (δ -56.0 ppm) in comparison to that of 2 (δ -59.3
ppm) suggests that the coupling of the two indolyl
substituents induces little strain in the resulting un-
conjugated six-membered phosphacycle.
While 31P coupling to the 13C resonances of 1 and 2
indicated that indole substitution had occurred,9 the
position of phosphorus substitution about the indole ring
awaited confirmation by X-ray crystallography. Single
crystals of 1 were grown by slow evaporation from
toluene. Figure 2 shows the molecular structure and
numbering scheme of the ligand, and Table 4 lists
selected bond distances and angles. Phosphine 1 crys-
tallizes in the space group P1h, with two crystallographi-
cally independent molecules in the asymmetric unit. The
independent molecules are adequately similar in struc-
ture, such that discussion is confined to one of them.12
The geometry about the phosphorus atoms is best
(11) Katritzky, A. R.; Lue, P.; Chen, Y.-X. J. Org. Chem. 1990, 55,
3688.
(12) The most significant difference between the two molecules is
the C(2)-P(1)-C(17) bond angles of 99.94(8) and 101.94(9)°.

2-Indolylphosphines
Organometallics, Vol. 24, No. 1, 2005 43
Table 4. Selected Bond Lengths (Å) and Angles
(deg) for Ligands 1 and 2 and N-Functionalized
Ligands (N-Bz)-1, (N-CH2NMe2)2-3, and (N-F5Bz)2-3
Compound 1
P(1A)-C(2A)
P(1A)-C(11A)
P(1A)-C(17A)
1.813(2)
1.838(2)
1.837(2)
N(1A)-C(9A)
N(1A)-C(2A)
1.378(2)
1.399(2)
C(2A)-P(1A)-C(11A) 101.64(8) C(9A)-N(1A)-C(2A) 109.3(6)
C(2A)-P(1A)-C(17A) 99.94(8) C(3A)-C(2A)-N(1A) 109.0(2)
C(11A)-P(1A)-C(17A) 102.97(8)
Compound 2
P(1)-C(2)
P(1)-C(12)
P(1)-C(21)
N(1)-C(9)
1.812(2)
N(1)-C(2)
1.398(3)
1.382(3)
1.395(3)
1.809(2)
1.841(2)
1.373(3)
N(11)-C(19)
N(11)-C(12)
C(2)-P(1)-C(12)
C(2)-P(1)-C(21)
C(1)-P(1)-C(21)
C(9)-N(1)-C(2)
C(3)-C(2)-N(1)
100.3(1)
101.3(1)
102.2(1)
109.1(2)
109.2(1)
N(1)-C(9)-C(4)
107.5(2)
109.3(2)
108.8(2)
107.3(2)
C(19)-N(11)-C(12)
C(13)-C(12)-N(11)
N(11)-C(19)-C(14)
Figure 2. ORTEP diagram of 1 showing the numbering
scheme. Ellipsoids are at the 35% probability level. All
hydrogen atoms except for the amine proton have been
omitted for clarity.
Compound (N-Bz)-1
P(1)-C(2)
P(1)-C(11)
P(1)-C(17)
1.819(2)
1.836(2)
1.831(2)
N(1)-C(9)
1.377(3)
1.400(3)
1.454(4)
described as trigonal pyramidal with the aromatic
substituents adopting a twisted propeller-blade-like
orientation. The P(1)-indolyl C(2) bond distance of
1.813(2) Å is significantly shorter than the bond dis-
tances from phosphorus to the R-C atoms of the phenyl
rings (average 1.838(2) Å). No chemical significance is
associated with the bond angle between the indolyl and
one of the phenyl substituents, C(2A)-P(1A)-C(17A)
(99.9(8)°), being significantly smaller than the other
bond angles of C(2A)-P(1A)-C(11A) (101.6(8)°) and
C(11A)-P(1A)-C(17A) (103.0(8)°). Bonding of phospho-
rus at the C2 position induces no important changes in
the structural features of the methylindolyl substituent.
It is evident from the crystal structure of 1 that the
C2-bound methylindolyl group constitutes a markedly
larger phosphorus substituent than the phenyl ring. An
average separation of 2.40(6) Å between the two phenyl
carbon atoms positioned ortho to phosphorus on each
ring serves as an effective measure of the width of the
phosphine’s two phenyl groups. In comparison, mea-
sured from its nitrogen atom to the methyl carbon atom
C(10A), the equivalent width of 3.713(4) Å for the
methylindolyl group of 1 suggests that the indolylphos-
phines 1 and 2 possess cone angles larger than that of
PPh3,13,14 perhaps bearing a closer similarity in size to
P(o-tolyl)3.15
Crystals of ligand 2 were grown from slow evaporation
of a saturated solution in dichloromethane. Figure 3
shows the molecular structure and numbering scheme
of the ligand, and Table 4 lists selected bond distances
and angles. Ligand 2 crystallizes in the space group P21/
c. The phosphorus atom adopts a trigonal-pyramidal
geometry with the aromatic substituents situated in a
twisted propeller-blade-like fashion, similar to the solid-
state structure of 1. Likely due to steric influences, the
indolyl substituents are oriented such that the methyl
moieties at the C(3) and C(13) positions point away from
the pyramid formed by the substituents around P(1).
In addition, the P(1)-indolyl C(2) and P(1)-indolyl
C(12) bond distances of 1.812(2) and 1.809(2) Å, respec-
N(1)-C(2)
N(1)-C(23)
C(2)-P(1)-C(11)
C(2)-P(1)-C(17)
C(11)-P(1)-C(17) 103.24(9) N(1)-C(23)-C(24) 113.6(2)
103.60(9) C(9)-N(1)-C(2)
101.0(1) C(3)-C(2)-N(1)
108.8(2)
108.4(2)
Compound (N-CH2NMe2)2-3
P(1)-C(2)
P(1)-C(12)
P(1)-C(20)
N(1)-C(9)
N(1)-C(2)
C(3)-C(10)
1.811(2)
1.814(2)
1.845(2)
1.383(3)
1.404(3)
1.492(3)
N(1)-C(26)
N(11)-C(19)
N(11)-C(12)
C(13)-C(10)
N(11)-C(30)
1.453(3)
1.379(3)
1.397(3)
1.503(3)
1.453(3)
C(2)-P(1)-C(12)
C(2)-P(1)-C(20)
C(12)-P(1)-C(20) 101.7(1)
C(9)-N(1)-C(2)
C(3)-C(2)-N(1)
N(1)-C(9)-C(4)
94.72(10) N(1)-C(26)-N(27)
101.3(1)
112.9(2)
C(19)-N(11)-C(12) 108.6(2)
C(13)-C(12)-N(11) 109.2(2)
N(11)-C(19)-C(14) 107.8(2)
N(11)-C(30)-N(31) 111.4(2)
108.0(2)
109.4(2)
108.3(2)
C(3)-C(10)-C(13)
113.0(2)
(N-F5Bz)2-3
P(1)-C(2)
P(1)-C(12)
P(1)-C(20)
N(1)-C(9)
N(1)-C(2)
1.802(2)
1.813(2)
1.844(2)
1.383(3)
1.399(3)
N(1)-C(26)
N(11)-C(19)
N(11)-C(12)
C(13)-C(10)
N(11)-C(33)
1.452(3)
1.378(3)
1.396(3)
1.497(3)
1.442(3)
C(3)-C(10)
1.494(3) N(1)-C(26)-C(27)
94.36(9)
103.20(9)
115.3(2)
C(2)-P(1)-C(12)
C(2)-P(1)-C(20)
C(19)-N(11)-C(12) 108.9(2)
C(13)-C(12)-N(11) 109.4(2)
N(11)-C(19)-C(14) 107.8(2)
N(11)-C(33)-C(34) 116.2(2)
C(12)-P(1)-C(20) 101.63(9)
C(9)-N(1)-C(2)
C(3)-C(2)-N(1)
N(1)-C(9)-C(4)
108.5(2)
109.3(2)
108.0(2)
C(3)-C(10)-C(13)
112.9(2)
tively, are shorter than the P(1)-phenyl C(21) bond
distance of 1.841(2) Å. As with 1, the bonding of the
phosphorus atom at the C2 positions on indolyl do not
impose chemically significant changes in the structural
features of its methylindolyl substituent.
Synthesis and Characterization of N-Substitut-
ed Ligands. The steric and electronic properties of
ligands 1-3 were modified with a variety of substituents
introduced at the indole nitrogen positions. Function-
alization proceeded by initial NaH deprotonation of the
indolylphosphine’s nitrogen atoms followed by the ad-
dition of the appropriate alkyl halide to afford the target
ligand in moderate yields. Table 1 lists the N-function-
alized derivatives of ligands 1-3 that have been syn-
thesized, their corresponding 31P NMR chemical shifts,
(13) Bunten, K. A.; Chen, L.; Fernandez, A. L.; Poe, A. J. Coord.
Chem. Rev. 2002, 233-234, 41.
(14) Mueller, T. E.; Mingos, D. M. P. Transition Met. Chem. 1995,
20, 533.
(15) Tolman, C. A. Chem. Rev. 1977, 77, 313.

44 Organometallics, Vol. 24, No. 1, 2005
Yu et al.
Figure 3. ORTEP diagram of 2 showing the numbering
scheme. Ellipsoids are at the 35% probability level. All
hydrogen atoms except for the amine protons have been
omitted for clarity.
Figure 5. ORTEP diagram of (N-CH2NMe2)2-3 showing
the numbering scheme. Ellipsoids are at the 35% prob-
ability level. All hydrogen atoms have been omitted for
clarity.
of the phenyl moieties on P(1) with a ring-to-ring
distance of 4.413 Å. The benzylated methylindolyl
substituent represents a significantly larger phosphorus
substituent than the phenyl moieties. The analogous
width of the benzylated methylindolyl, measured from
indolyl’s methyl carbon atom C(10) to the N-substituted
methylene carbon C(23), was determined to be 5.061(4)
Å, suggesting that the introduction of any group on the
indolyl nitrogen renders that phosphine substituent a
cone angle markedly greater than that of a phenyl
group.
Crystals of aminal-protected 3, (N-CH2NMe2)2-3,
were grown by solvent vapor diffusion of pentane into
a solution of the phosphine in dichloromethane. The
protected ligand crystallized in the monoclinic space
group P21/c. Figure 5 shows the molecular structure and
numbering scheme of the ligand, and Table 4 lists
selected bond distances and angles. The X-ray structure
determination of (N-CH2NMe2)2-3 confirmed the incor-
poration of the phosphorus atom P(1) into the six-
membered ring through bonding to the coupled indolyl
substituent at its two C2 positions, C(2) and C(12).
The formation of the phosphacycle was also evident
in the structure determination of (N-F5Bz)2-3, single
crystals of which were obtained by slow solvent evapo-
ration from a CDCl3 solution of the phosphine. (N-
F5Bz)2-3 crystallizes in the monoclinic space group
P21/n with one deuteriochloroform solvent molecule
present. Figure 6 shows the molecular structure and
numbering scheme of (N-F5Bz)2-3, and Table 4 lists
selected bond distances and angles. A comparison of its
solid-state structure with that of (N-CH2NMe2)2-3
reveals that the replacement of the electron-rich aminal
groups with the electron-withdrawing pentafluorobenzyl
substituents imparts little structural change upon the
rest of the molecule. For example, the P(1)-C(2) and
P(1)-C(12) bond lengths of 1.802(2) and 1.813(2) Å,
respectively, in (N-F5Bz)2-3 are effectively the same as
the analogous bond lengths of 1.811(2) and 1.814(2) Å
in (N-CH2NMe2)2-3 and are not significantly different
from the P(1)-indolyl C(2) separation of 1.813(2) Å
observed in 1. Consistent with the 31P NMR behavior
of 3, the structural data for both derivatives of 3 suggest
that their six-membered rings do not experience sub-
Figure 4. ORTEP diagram of (N-Bz)-1 showing the
numbering scheme. Ellipsoids are at the 35% probability
level. All hydrogen atoms have been omitted for clarity.
and their yields. The introduction of these diverse
substituents â to the phosphorus center demonstrates
a facile and general route to systematically adjust the
steric environment and electronic character of the
phosphorus center in these ligands. This modular ap-
proach to creating new phosphines through substituent
modification following P-substituent bond formation lies
in contrast to the more customary methods of phosphine
synthesis. Therein, the challenging and often substitu-
ent-specific intricacies and vagaries of P-C bond forma-
tion must be overcome each time that a different
structural element of interest is incorporated into the
phosphine.
All of the ligand derivatives have been fully charac-
terized using high-resolution mass spectrometry and
1
31P, H, and 13C NMR spectroscopy. Single crystals of
(N-Bz)-1 were obtained from slow evaporation of a
saturated solution of the ligand in dichloromethane.
Figure 4 shows the molecular structure and numbering
scheme of the ligand, and Table 4 lists selected bond
distances and angles. The ligand (N-Bz)-1 crystallizes
in the monoclinic space group P21/c. The geometry about
P(1) is trigonal pyramidal, and the aromatic substitu-
ents are oriented in a similar fashion as 1 and 2. The
benzyl group adopts an orientation in which it forms a
slipped pseudo-eclipsed π-stacking interaction with one

2-Indolylphosphines
Organometallics, Vol. 24, No. 1, 2005 45
Figure 7. ORTEP diagram of complex 4 showing the
numbering scheme. Ellipsoids are at the 35% probability
level. All hydrogen atoms except for the amine protons have
been omitted for clarity. Intramolecular hydrogen bonding
is also exhibited.
Figure 6. ORTEP diagram of (N-F5Bz)2-3 showing the
numbering scheme. Ellipsoids are at the 35% probability
level. All hydrogen atoms and the CHCl3 solvent molecule
have been omitted for clarity.
stantial ring strain. The respective C(3)-C(10)-C(13)
bond angles of 113.0(2) and 112.9(2)° about the meth-
ylene carbon of the phosphacycles of (N-CH2NMe2)2-3
and (N-F5Bz)2-3 are only slightly smaller than the
corresponding bond angle of 115.4(2)° measured in 3,3′-
diindolylmethane.16 Interestingly, coupling of the indolyl
substituents does produce a compression of almost 6°
upon the C(2)-P(1)-C(12) bond angle from comparison
of the values of 94.72(10) and 94.36(9)° in (N-
CH2NMe2)2-3 and (N-F5Bz)2-3, respectively, with that
of 100.3(1)° measured between the uncoupled indolyl
substituents of 2. This is not considered to impart
significant ring strain to the phosphacycle, because of
the facility with which phosphorus subtlely changes
hybridization in order to accommodate substituents of
differing electronic or steric requirements. The six-
membered rings are essentially planar in both struc-
tures with a root-mean-square deviation of less than
0.02Å.
In the solid state, the aminal-protecting groups of (N-
CH2NMe2)2-3 and the pentafluorobenzyl groups of (N-
F5Bz)2-3 both adopt conformations in which they are
oriented in the same direction as the phenyl substituent
on the phosphorus atom. The fluorinated benzyl groups
additionally exhibit a slipped pseudo-eclipsed π-stacking
conformation with the lone phenyl substituent of P(1).
Distances between ring centroids of 3.547 and 3.805 Å
and an angle of 146° described by them suggest the
near-planar π-stacking of the three rings.
Figure 8. ORTEP diagram of complex 5 showing the
numbering scheme. Ellipsoids are at the 35% probability
level. All hydrogen atoms except for the amine protons have
been omitted for clarity. Intramolecular hydrogen bonding
is also exhibited.
Complexes 4-6 were obtained by the addition of
acetonitrile solutions of 1 equiv of 1-3, respectively, to
a solution of Pd(COD)Cl2 in acetonitrile. After the
mixture was stirred for 15 min at ambient temperature,
dark orange-red solids were obtained upon removal of
the solvent under reduced pressure. The Pd(II) com-
plexes were recrystallized in good yields from dichlo-
romethane-hexanes or dichloromethane-diethyl ether
mixtures. Complexation of 1-3 to Pd(II) resulted in the
downfield displacement of their 31P NMR chemical shifts
from -33.1, -59.3, and -56.0 ppm, respectively, to 14.6
ppm for [PdP(C6H5)2(C9H8N)Cl(µ-Cl)]2 (4), -5.7 ppm for
[PdP(C6H5)(C9H8N)2Cl(µ-Cl)]2 (5), and -14.9 ppm [PdP-
(C6H5)(C17H12N2)Cl(µ-Cl)]2 (6).
The structures of 4 and 5 were confirmed by X-ray
crystallography. Single crystals of sufficient quality
were obtained for 4 and 5 from solvent vapor diffusion
of hexanes and diethyl ether, respectively, into a solu-
tion of each complex in dichloromethane. Figures 7 and
8 show the molecular structures and numbering schemes
for complexes 4 and 5, respectively, while Table 5 lists
selected bond distances and angles. Complexes 4 and 5
are isostructural in the solid state, consisting of discrete
molecules of dimeric [Pd(1)Cl(µ-Cl)]2 and [Pd(2)Cl(µ-
Cl)]2, respectively, sitting about crystallographic inver-
sion centers in the monoclinic space group P21/c. Both
structures exhibit the expected square-planar coordina-
tion geometry about the Pd center and share a number
Synthesis and Characterization of the Com-
plexes [Pd(1)Cl(µ-Cl)]2 (4), [Pd(2)Cl(µ-Cl)]2 (5), and
[Pd(3)Cl(µ-Cl)]2 (6). Phosphines 1-3 were reacted with
Pd(II) in order to demonstrate P-coordination of the
ligands exclusively. In reaction with Pd(COD)Cl2, dis-
placement of COD provides two sites of coordination
with which an indolylphenylphosphine such as 1 may
act as either a monodentate P-donor or as a chelating
or bridging bidentate P,N-Lewis base.
(16) Rampersad, N. C.; Farrar, D. H. Unpublished results.

46 Organometallics, Vol. 24, No. 1, 2005
Yu et al.
Table 5. Selected Bond Lengths (Å) and Angles
(deg) for Complexes 4-6
Compound 4
Pd(1)-Cl(1)
Pd(1)-Cl(2)
Pd(1)-P(1)
P(1)-C(2)
2.3209(6)
2.2796(7)
2.2332(7)
1.797(3)
P(1)-C(11)
P(1)-C(17)
N(1)-C(9)
N(1)-C(2)
1.810(3)
1.808(3)
1.366(4)
1.379(4)
Pd(1)-P(1)-C(2)
Pd(1)-P(1)-C(11)
Pd(1)-P(1)-C(17)
C(2)-P(1)-C(11)
C(2)-P(1)-C(17)
116.5(1)
112.9(9)
107.2(9)
102.9(1)
109.9(1)
C(11)-P(1)-C(17)
C(9)-N(1)-C(2)
C(3)-C(2)-N(1)
N(1)-C(9)-C(4)
107.2(1)
109.1(3)
109.5(3)
107.7(3)
Compound 5
Pd(1)-Cl(1)
Pd(1)-Cl(2)
Pd(1)-P(1)
P(1)-C(2)
2.319(2)
2.269(2)
2.220(2)
1.795(8)
1.790(8)
P(1)-C(21)
N(1)-C(9)
1.805(7)
1.370(10)
1.388(9)
1.380(9)
1.403(9)
N(1)-C(2)
N(11)-C(19)
N(11)-C(12)
Figure 9. ORTEP diagram of complex 6 showing the
numbering scheme. Ellipsoids are at the 35% probability
level. All hydrogen atoms except for the amine protons have
been omitted for clarity. Intramolecular hydrogen bonding
is also exhibited.
P(1)-C(12)
Pd(1)-P(1)-C(2)
112.6(2) C(9)-N(1)-C(2)
108.8(6)
109.7(6)
107.5(6)
Pd(1)-P(1)-C(12) 113.5(3) C(3)-C(2)-N(1)
Pd(1)-P(1)-C(21) 110.3(3) N(1)-C(9)-C(4)
C(2)-P(1)-C(12)
C(2)-P(1)-C(21)
C(12)-P(1)-C(21) 106.2(3) N(11)-C(19)-C(14) 108.7(6)
104.6(3) C(19)-N(11)-C(12) 107.2(6)
109.3(4) C(13)-C(12)-N(11) 110.0(6)
angles of approximately 4-5° commonly seen upon
metal coordination21 is also observed upon the bonding
of 1 and 2 to Pd(II). The structures confirm that
monodentate P-coordination of 1 and 2 to Pd(II) does
not sufficiently increase the acidity of the ligand’s
nitrogen center to result in the indolyl substituent
serving as an additional site for metal coordination in
the absence of base.
Consistent with their characteristic resonances at δ
∼10 ppm which were observed in the 1H NMR of 4 and
5, the difference electron density map confirmed the
presence of a proton about each indolyl nitrogen center.
The NH moieties of the coordinated indolylphosphines
demonstrate a degree of acidic character in their
hydrogen bonding in the palladium complexes. Intramo-
lecular hydrogen-bonding contacts are evident between
N(1)-H(1A) and the terminally bound Cl(2) in 4 (Figure
7). Similar intramolecular hydrogen-bonding interac-
tions exist between the terminal Cl(2) in 5 and the
N(11)-H(11A) group of the suitably orientated indolyl
substituent.
Compound 6
Pd(1)-Cl(1)
Pd(1)-Cl(2)
Pd(1)-P(1)
P(1)-C(2)
2.3163(7)
2.2901(8)
2.2162(8)
1.772(3)
1.778(3)
P(1)-C(20)
N(1)-C(9)
1.807(3)
1.365(4)
1.384(4)
1.377(4)
1.388(4)
N(1)-C(2)
N(11)-C(19)
N(11)-C(12)
P(1)-C(12)
Pd(1)-P(1)-C(2)
Pd(1)-P(1)-C(12) 110.1(1) C(3)-C(2)-N(1)
Pd(1)-P(1)-C(20) 111.3(1) N(1)-C(9)-C(4)
C(2)-P(1)-C(12)
C(2)-P(1)-C(20)
C(12)-P(1)-C(20) 110.4(1)
117.4(1) C(9)-N(1)-C(2)
108.6(2)
109.9(3)
108.0(3)
99.1(1) C(19)-N(11)-C(12) 108.2(2)
107.9(1) C(13)-C(12)-N(11) 110.1(2)
of structural similarities with previously characterized
[Pd(L)Cl(µ-Cl)]2 dimers. Most notably, the Pd-P bond
lengths of 2.233(7) and 2.220(2) Å for 4 and 5, respec-
tively, are consistent with Pd-P bond lengths reported
for other palladium-phosphine complexes.21,22 Com-
parisons of the bond angles between phosphine substit-
uents of 1 with those of 4 as well as comparisons of those
of 2 with those of 5 show that the increase in bond
Single crystals of 6 were obtained from solvent vapor
diffusion of hexanes into a solution of the complex in
dichloromethane. Figure 9 shows the molecular struc-
ture and numbering scheme of the complex, and Table
5 lists selected bond distances and angles. The dimeric
complex 6 crystallizes in the space group P1h, with each
half of the dimer sitting about a crystallographic inver-
sion center. Per asymmetric unit, there is one molecule
of water and one molecule of dichloromethane also
present in the lattice.
As exhibited in 4 and 5, the Pd center in 6 adopts the
expected square-planar coordination geometry, and
monodentate P-coordination of the ligand is obtained.
Structural consequences derived from coordination of
the phosphine 3 in complex 6 can be acquired from a
comparison of its solid-state structure with those of the
free N-substituted derivatives of 3. This reveals that the
C(3)-C(10)-C(13) bond angle of 113.9(2)° in the phos-
phacycle of 6 remains essentially unchanged from the
values observed in (N-CH2NMe2)2-3 and (N-F5Bz)2-3.
Nevertheless, the 4-5° increase in bond angle between
indolyl substituents observed upon P-coordination to Pd-
(II) in 5 is still seen in 6 and implies that coupling of
(17) Gaw, K. G.; Slawin, A. M. Z.; Simth, M. B. Organometallics
1999, 18, 3255.
(18) Barkley, J.; Ellis, M.; Higgins, S. J.; McCart, M. K. Organo-
metallics 1998, 17, 1725.
(19) Hassan, F. S. M.; McEwan, D. M.; Pringle, P. G.; Shaw, B. L.
J. Chem. Soc., Dalton Trans. 1985, 1501.
(20) Hietkamp, S.; Stufkens, D. J.; Vrieze, K. J. Organomet. Chem.
1979, 169, 107.
(21) (a) Coles, S. J.; Faulds, P.; Hursthouse, M. B.; Kelly, D. G.;
Ranger, D. C.; Toner, A. J.; Walker, N. M. J. Organomet. Chem. 1999,
586, 234. (b) Slawin, A. M. Z.; Woollins, J. D.; Zhang, Q. Inorg. Chem.
Commun. 1999, 2, 386. (c) Vinogradova, N. M.; Odinets, I. L.; Lyssenko,
K. A.; Pasachnik, M. P.; Petrovskii, P. V.; Mastryukova, T. A. Mendeleev
Commun. 2001, 219. (d) Cobley, C. J.; Ellis, D. D.; Orpen, A. G.;
Pringle, P. G. Dalton 2000, 1101. (e) Brodie, N.; Goubard, F.; Tabuteau,
A.; Halut, S. Mater. Res. Bull. 1998, 33, 1739. (f) Fenske, D.; Prokscha,
H.; Becher, H. J. Z. Naturforsch., B 1980, 35, 1075. (g) Li, G. Y. Angew.
Chem., Int. Ed. 2001, 40, 1513. (h) Dyson, P. J.; Steed, J. W.; Sunman,
P. CrystEngComm 1999, 2.
(22) (a) Dinger, M. B.; Scott, M. J. Inorg. Chem. 2001, 40, 856. (b)
Vincente, J.; Lagunas, M. C.; Bleuet, E.; Ramirez de Arellano, M. C.
Private communication, 1997. (c) Dyer, P. W.; Dyson, P. J.; James, S.
L.; Sunman, P.; Davies, J. E.; Martin, C. M. Chem. Commun. 1998,
1375. (d) Grisby, W. J.; Nicholson, B. K. Acta Crystallogr., Sect. C:
Cryst. Struct. Commun. 1992, 48, 362. (e) Hydrio, J.; Gouygou, M.;
Dallemar, F.; Balavoine, G. G. A.; Daran, J.-C. J. Organomet. Chem.
2002, 643, 19. (f) Liu, X.; Ong, T. K. W.; Selvaratnam, S.; Vittal, J. J.;
White, A. J. P.; Williams, D. J.; Leung, P.-H. J. Organomet. Chem.
2002, 643, 4. (g) Chaloner, P. A.; Dewa, S. Z.; Hitchcock, P. B. Acta
Crystallogr., Sect. C: Cryst. Struct. Commun. 1995, 51, 232.

2-Indolylphosphines
Organometallics, Vol. 24, No. 1, 2005 47
nylphosphines. The solid-state structures of ligands 1-3
have established the bonding of the phosphorus center
to the C2 position of their respective indolyl substitu-
ents. The N-functionalization of these indolylphos-
phines, confirmed in the solid-state structure of (N-
F5Bz)2-3, affords a variety of electron-withdrawing,
electron-donating, and chiral indolyl substituents that
may be easily introduced â to the phosphorus center.
This ability to systematically alter the steric environ-
ment and electronic character of the phosphorus center
with such facility has been a frequently cited but rarely
achieved goal in phosphine synthesis and offers the
opportunity to confer a spectrum of interesting charac-
teristics upon the resulting ligands. Studies are cur-
rently underway examining the effectiveness of these
and related ligands in catalysis and other important
applications as a function of their steric and electronic
properties.
In their subsequent coordination to Pd(II), the ability
of these potentially P,N-bidentate ligands to act as
monodentate P-donor ligands was confirmed by the
X-ray crystallographic characterization of the products
4-6 as dimeric palladium complexes of the type [Pd-
(L)Cl(µ-Cl)]2. While facile deprotonation of the indolyl
nitrogen atoms of the complexed ligands does not occur,
the prevalence of extensive intra- and intermolecular
hydrogen-bonding interactions in the structure of each
palladium complex 4-6 suggests that the NH groups
of these ligands may indeed serve as centers of further
reactivity. To this end, we have recently shown that the
deprotonation of an indolylphosphine ligand of 4 leads
to clean aggregation of the palladium dimer, in which
the ligand serves as a bridging bidentate P,N-donor. We
also have demonstrated the stepwise and controlled
coordination of each of the phosphines 1-3, initially as
a P-donor and subsequently as an N-donor, in their
reaction with Ru3(CO)12. These results will be reported
elsewhere.
Figure 10. Extended hydrogen-bonding network of com-
plex 6. The dichloromethane solvent molecules have been
omitted for clarity.
the indolyl substituents does not inhibit their “fanning
out” upon P-coordination. The introduction of ring strain
in the phosphacycle of 6 that may ensue from this
fanning out is consistent with the upfield shift in 31P
NMR resonance of 6 relative to that of 5, which is
suggestive of a phosphorus center in a strained bonding
environment.18-21 A deviation from coplanarity of 5.6-
(1)° between the two indolyl groups indicates that the
coupled indole remains effectively planar upon P-
coordination.
Symmetry-related dimers of 6 pack in a laddered
head-to-tail fashion that extends up the a axis of the
unit cell. Both crystallographically independent indolyl
NH groups of each dimer are involved in hydrogen
bonding either within or between the dimeric units of
the ladder, as shown in Figure 10. One NH group
intramolecularly hydrogen bonds to its neighboring
terminal chloride, as observed in 4 and 5. The other NH
group hydrogen bonds to the oxygen atom of solvate
water, which completes a cyclic network by hydrogen
bonding in turn to the terminal chloride of a symmetry-
related dimer. The dichloromethane solvate has no
significant intermolecular contacts.
Acknowledgment. We thank Mr. Dan Mathers for
performing elemental analyses and Dr. A. Young for
mass spectrometry analyses. J.O.Y. and E.L. thank the
University of Toronto Open Fellowship for financial
support. N.C.R. and J.L.S. also appreciate the award
of scholarships from Digital Specialty Chemicals Ltd.
and the National Sciences and Engineering Research
Council of Canada.
Supporting Information Available: Tables giving X-ray
crystallographic data for ligands 1 and 2, the N-functionalized
ligands (N-Bz)-1, (N-CH2NMe2)2-3, and (N-F5Bz)2-3, and
complexes 4-6. This material is available free of charge via
the Internet at http://pubs.acs.org.
Conclusion
This report describes the synthetic methods for the
preparation of a series of novel C2-bound indolylphe-
OM0401004