2-Thioanisyldichlorophosphine, new starting material for the preparation of multidentate phosphine ligands: Syntheses and characterization of derivatives of 2-anisyl- and 2-thioanisyldichlorophosphines

Article abstract of DOI:10.1016/S0022-328X(99)00711-1

A new aryldichlorophosphine, 2-thioanisyldichlorophosphine, and its anisyl analogue, 2-anisyldichlorophosphine, were prepared by using an organozinc halide reagent of 2-thioanisole or 2-anisole with ethereal solution of PCl₃ in refluxing conditions. From these aryldichlorophosphines, eight new multidentate phosphine ligands containing 2-thioanisyl, 4-thioanisyl, 2-anisyl, 1-naphthyl and 9-anthracenyl groups were synthesized and characterized. Characterization was based mainly on NMR spectroscopy and X-ray crystallography. The crystal structures of six ligands are reported. The electronic effects on basicity of ligands are discussed.

Full text of DOI:10.1016/S0022-328X(99)00711-1

www.elsevier.nl/locate/jorganchem
Journal of Organometallic Chemistry 598 (2000) 235–242
2-Thioanisyldichlorophosphine, new starting material for the
preparation of multidentate phosphine ligands: syntheses and
characterization of derivatives of 2-anisyl- and
2-thioanisyldichlorophosphines
Riitta H. Laitinen a,*, Ville Heikkinen b, Matti Haukka c, Ari M.P. Koskinen b,
Jouni Pursiainen b
a Kemira Chemicals Oy, PO Box 171, FIN-90101 Oulu, Finland
b Department of Chemistry, Uni6ersity of Oulu, PO Box 3000, FIN-90401 Oulu, Finland
c Department of Chemistry, Uni6ersity of Joensuu, PO Box 111, FIN-80101 Joensuu, Finland
Received 11 August 1999; received in revised form 9 November 1999
Abstract
A new aryldichlorophosphine, 2-thioanisyldichlorophosphine, and its anisyl analogue, 2-anisyldichlorophosphine, were pre-
pared by using an organozinc halide reagent of 2-thioanisole or 2-anisole with ethereal solution of PCl3 in refluxing conditions.
From these aryldichlorophosphines, eight new multidentate phosphine ligands containing 2-thioanisyl, 4-thioanisyl, 2-anisyl,
1-naphthyl and 9-anthracenyl groups were synthesized and characterized. Characterization was based mainly on NMR spec-
troscopy and X-ray crystallography. The crystal structures of six ligands are reported. The electronic effects on basicity of ligands
are discussed. © 2000 Elsevier Science S.A. All rights reserved.
Keywords: Dichlorophosphines; Phosphine ligands; 31P-NMR spectroscopy; Basicity
1. Introduction
chlorophosphines, the para isomer being the main
product. Deactivating, meta-directing groups prevent
the substitution [7].
Phosphine ligands are commonly used in modifying
activities and selectivities of homogeneous metal cata-
lysts. In the preparation of phosphines, aryl- and
alkylchlorophosphines are important intermediates [1].
The number of commercially available arylchlorophos-
phines is, however, limited, suggesting that the prepara-
tion is not always straightforward.
Several other methods have also been used in the
preparation of dichlorophosphines. Large excess of
PCl3 [9], chlorobis(diethylamino)phosphine as an inter-
mediate [10] and Grignard reagent combined with
ZnCl2 [11] are examples of these methods. These meth-
ods, however, failed in the synthesis of 2-thioani-
syldichlorophosphine, and we had to search for new
synthetic routes.
In this work we describe an improved route [11] for
the preparation of ortho-substituted aryldichlorophos-
phines. The preparation and characterization of the
title compound, 2-thioanisyldichlorophosphine (1), is
reported. Also the corresponding 2-anisyldichlorophos-
phine (2) is prepared using the same method. Addition-
ally, eight new phosphines (3–10) are synthesized from
2-anisyl- and 2-thioanisyldichlorophosphines.
A
century ago Michaelis prepared 4-ani-
syldichlorophosphine by aluminum trichloride-cata-
lyzed Friedel–Crafts reaction [2]. Modifications of this
original method have been commonly used in the
preparation of aryldichlorophosphines since then [3–8].
The original method typically leads to a mixture of
ortho and para isomers of substituted aromatic
* Corresponding author. Tel.: +358-10-861-214; fax: +358-10-
8625-678.
E-mail address: riitta.laitinen@kemira.com (R.H. Laitinen)
0022-328X/00/$ - see front matter © 2000 Elsevier Science S.A. All rights reserved.
PII: S0022-328X(99)00711-1

236
R.H. Laitinen et al. / Journal of Organometallic Chemistry 598 (2000) 235–242
2. Experimental
isole (Aldrich), 4-bromothioanisole (Aldrich), 2-
bromoanisole (Aldrich), 9-bromoanthracene (Aldrich),
n-butyllithium (Aldrich), 1-bromonaph-thalene (Merck)
and trichlorophosphine (Merck) were obtained from
the indicated suppliers and used without further purifi-
ZnCl2 (Aldrich) was dried in vacuum and diethyl
ether (Lab Scan) was distilled from sodium–benzophe-
none ketyl under nitrogen before use. 2-Bromothioan-
Table 1
Crystallographic data
Ligand
3
4
5
7
8
9
Chemical formula
Temperature (K)
Molecular weight (g mol−1
Crystal size (mm)
Color
Crystal system
Space group
Unit cell dimensions
C35H25PS
120
508.58
0.3×0.3×0.3
Orange
Triclinic
C27.5H22PSCl a C21H21PS3
C35H25OP
120
492.52
0.2×0.3×0.4
Orange–yellow
Triclinic
C27H21OP
120
392.41
0.2×0.3×0.3
Colorless
Orthorhombic
P212121
C21H21OPS2
120
384.47
0.3×0.4×0.4
Colorless
Monoclinic
P21/c
120
293
)
450.93
400.53
0.2×0.2×0.4
Colorless
Trigonal
0.2×0.3×0.3
Colorless
Triclinic
(
(
(
(
P1
R3
P1
P1
,
a (A)
9.893(2)
11.233(2)
11.578(2)
95.94(3)
98.73(3)
100.41(3)
1239.5(4)
2
37.209(5)
9.3640(10)
11.141(2)
11.8180(10)
112.942(10)
103.038(11)
105.715(12)
1013.8(2)
2
11.179(2)
11.603(2)
11.708(2)
119.30(3)
109.26(3)
91.09(3)
1219.8(4)
2
7.8912(16)
15.170(3)
16.910(3)
18.038(4)
9.6995(19)
23.160(5)
,
b (A)
,
c (A)
h (°)
i (°)
9.0416(18)
105.65(3)
k (°)
V (nm3)
10841(3)
18
1.243
0.324
4230
2024.2(7)
4
1.288
0.151
824
3902.0(13)
8
1.309
0.361
1616
Z
Dcalc. (Mg m−3
)
1.363
0.219
532
1.312
0.446
420
1.341
0.141
516
Absorption coefficient v (mm−1
F(000)
)
q range (°)
h range
k range
l range
No. of collected reflections
No. of unique reflections
No. of observed reflections
[I\2|(I)]
3.82–27.49
−12“12
−12“12
−15“15
10338
3.79–25.00
−44“44
−44“44
−10“10
23624
2.02–24.99
−1“11
−13“13
−14“13
4267
2.06–26.00
−13“13
−13“13
−14“14
8239
2.91–24.98
−8“8
−18“17
−20“19
3402
1.89–26.37
−20“20
−12“12
−28“28
14256
5220
4102
4229
3492
3554
2824
4268
3515
3402
3109
7492
6411
No. of parameters
Final R indices [I\2|(I)]
wR2 [I\2|(I)]
336
290
290
435
264
577
0.0379
0.0937
1.015
0.0609
0.1601
1.114
0.0342
0.0890
1.029
0.0387
0.0922
1.026
0.0336
0.0737
1.050
0.0345
0.0924
1.044
Goodness-of-fit
a (oSP(naf)2)·1/2(CH2Cl2).
Table 2
,
Selected bond lengths (A)
Ligand
3
4
5
7
8
9
P1ꢀC1
P1ꢀC7
P1ꢀC13
S1ꢀC2
1.8432(19)
1.8434(18)
1.8543(18)
1.7688(19)
1.832(3)
1.847(2)
1.835(2)
1.832(2)
1.772(2)
1.8516(19)
1.8559(19)
1.851(2)
1.832(2)
1.840(2)
1.8349(19)
1.8312(18)
1.8349(18)
1.8384(18)
1.829(3)
1.833(3)
1.765(4)
S1ꢀC4
1.7640(18)
1.791(2)
1.7644(18)
1.795(2)
S1ꢀC19
S2ꢀC10
S2ꢀC20
S3ꢀC16
S3ꢀC21
O1ꢀC2
O1ꢀC19
O3ꢀC14
O3ꢀC21
1.8022(19)
1.794(5)
1.786(3)
1.766(2)
1.784(3)
1.763(2)
1.770(5)
1.370(2)
1.431(2)
1.377(2)
1.432(3)
1.376(2)
1.431(2)

R.H. Laitinen et al. / Journal of Organometallic Chemistry 598 (2000) 235–242
237
Table 3
Selected bond angles (°)
Ligand
3
4
5
7
8
9
C1ꢀP1ꢀC7
104.71(8)
102.38(8)
114.30(8)
102.91(9)
103.28(15)
100.44(14)
104.70(15)
102.7(2)
100.06(9)
100.89(9)
104.21(9)
104.01(5)
104.62(8)
98.92(8)
110.83(8)
103.14(9)
104.13(9)
100.55(9)
99.94(8)
101.81(8)
101.42(8)
C1ꢀP1ꢀC13
C7ꢀP1ꢀC13
C2ꢀS1ꢀC19
C4ꢀS1ꢀC19
C10ꢀS2ꢀC20
C16ꢀS3ꢀC21
C2ꢀO1ꢀC19
C14ꢀO3ꢀC21
103.65(9)
102.78(10)
103.37(13)
104.53(16)
118.37(16)
117.60(17)
117.33(15)
cation. Standard Schlenk techniques were applied in
synthesis. Characterization of the compounds was
37.4%) was obtained as a colorless liquid. b.p. 86–
1
89°C/0.1 torr. H-NMR (200 MHz, CDCl3) l 3.9 (s,
1
3
4
based mainly on H-, 13C- and 31P-NMR spectroscopy.
H7, 3H), 6.9 (dd, JHꢀH 8.1 Hz, JHꢀP 6.0 Hz, H3, 1H),
3
3
NMR spectra were recorded on a Bruker AM200 and
Bruker DPX400 spectrometers. 1H and 13C spectra
were referenced to TMS, and 31P spectra to 85%
H3PO4. X-ray diffraction data were collected with a
Nonius KappaCCD or with a Nonius Mach3 diffrac-
tometer using Mo–Ka radiation.
7.1 (t, JHꢀH 7.7 Hz, H5, 1H), 7.5 (t, JHꢀH 7.7 Hz, H4,
3
4
1H), 7.9 (dd, JHꢀH 7.7 Hz, JHꢀP 3.4 Hz, H6, 1H).
13C{1H}-NMR (100 MHz, CDCl3) l 56.1 (s, C7, 1C),
1
111.0 (s, C3, 1C), 121.7 (s, C5, 1C), 127.4 (d, JCꢀP 59.9
Hz, C1, 1C), 130.8 (s, C6, 1C), 134.2 (s, C4, 1C), 160.7
2.1. Syntheses and characterization of starting
materials
2.1.1. 2-Thioanisyldichlorophosphine (1)
2-Bromothioanisole (3.0 ml, 5 g, 25 mmol) was lithi-
ated in diethyl ether (40 ml) at 0°C with n-butyl lithium
(10 ml, 2.5 M in hexane, 25 mmol). The reaction
mixture was stirred for 2 h at 0°C, after which an
ethereal solution (40 ml) of ZnCl2 (3.3 g, 25 mmol) was
added. Stirring was continued for 2 h at room tempera-
ture (r.t.) to ensure the formation of organozinc halide
reagent, which was then added to a solution of PCl3
(6.6 ml, 75 mmol) in diethyl ether (30 ml) at 0°C. The
reaction mixture was then refluxed for 40 h, cooled to
r.t. and the solvent was distilled at the normal pressure.
The crude product was distilled under reduced pressure.
The product (1.5 g, 6.6 mmol, 26.3%) was obtained as
Fig. 1. Crystal structure of (2-thiomethylphenyl)bis(9-anthracenyl)-
phosphine.
1
a colorless liquid. b.p. 100–104°C/0.1 torr. H-NMR
(400 MHz, CDCl3) l 2.5 (s, H7, 3H), 7.4–7.6 (m,
3
H4ꢀH6, 3H), 8.1 (d, JHꢀH 8.0 Hz, H3, 1H). 13C{1H}-
4
NMR (100 MHz, CDCl3) l 20.5 (d, JCꢀP 4.1 Hz, C7,
3
1C), 128.4 (s, C5, 1C), 130.4 (d, JCꢀP 3.9 Hz, C3, 1C),
1
132.5 (s, C4, 1C), 132.9 (s, C6, 1C), 140.6 (d, JCꢀP 38.2
2
Hz, C1, 1C), 142.1 (d, JCꢀP 52.6 Hz, C2, 1C). 31P{1H}-
NMR (162 MHz, CDCl3) l 150.5 (s). Anal. Calc. for
C7H7Cl2PS: C, 37.4; H, 3.1; S, 14.2. Found: C, 38.0; H,
3.5; S, 14.8%.
2.1.2. 2-Anisyldichlorophosphine (2)
2-Anisyldichlorophosphine was prepared using the
method described above. The mixture was refluxed for
20 h. 2-Anisyldichlorophosphine (2) (3.9 g, 18.7 mmol,
Fig. 2. Crystal structure of (2-methoxyphenyl)bis(4-thiomethyl-
phenyl)phosphine.

238
R.H. Laitinen et al. / Journal of Organometallic Chemistry 598 (2000) 235–242
after which 2-aryldichlorophosphine in Et2O was
added. The mixture was stirred an additional 1–2 h at
0°C. The precipitate was filtered and dried in vacuum.
The product was recrystallized from ethanol or
ethanol–toluene solution.
Scheme 1. Synthetic route for the preparation of 2-thioanisyl- and
2-anisyldichlorophosphine.
2.3. Characterization of phosphine ligands
2.3.1. (2-Thiomethylphenyl)bis(9-anthracenyl)phosphine
(SPanthr2) (3)
1
Yield 0.7 g, 1.3 mmol, 64.3%. m.p. 231–232°C. H-
NMR (200 MHz, CDCl3) l 2.3 (s, H15, 3H), 6.9 (m, H6,
1H), 7.0 (m, H5, 1H), 7.1 (m, H11, 4H), 7.2–7.4 (m, H3,
3
H4 and H10, 6H), 8.0 (d, JHꢀH 8.1 Hz, H12, 4H), 8.5 (s,
3
4
H14, 2H), 8.7 (dd, JHꢀH 8.9 Hz, JHꢀP 3.4 Hz, H9, 4H).
13C{1H}-NMR (100 MHz, CDCl3) l 17.2 (d, JCꢀP 7.9
3
Hz, C15, 1C), 124.8 (s, C11, 4C), 125.3 (s, C5, 1C), 126.0
(s, C10, 4C), 126.6 (s, C14, 2C), 126.9 (s, C9, 4C), 127.1
(s, C3, 1C), 128.7 (s, C4, 1C), 129.5 (s, C12, 4C), 130.7 (s,
C13, 4C), 131.5 (s, C8, 4C), 133.0 (s, C6, 1C), 135.5 (d,
Scheme 2. Structures of the ligands prepared in this work.
1
1JCꢀP 14.1 Hz, C7, 2C), 136.8 (d, JCꢀP 10.9 Hz, C1, 1C),
Table 4
31P-NMR chemical shifts of the PR3-type phosphines and the corre-
sponding calculated increment values of the substituent groups
2
144.4 (d, JCꢀP 33.0 Hz, C2, 1C). 31P{1H}-NMR (162
MHz, CDCl3) l −38.4 (s). MS [M+1] Anal. Calc. for
P
C35H26PS, 509.149; found, 509.148.
Ligand
31P chemical shift
| increment
(l, ppm)
(l, ppm)
2.3.2. (2-Thiomethylphenyl)bis(1-naphthyl)phosphine
(SPnaf2) (4)
Yield 0.2 g, 0.5 mmol, 53.4%. m.p. 204–205°C. H-
(o-MeSC6H4)3P
(p-MeSC6H4)3P
(o-MeOC6H4)3P
P(naf)3
−30.2 [32]
−8.3 [33]
−37.1 [32]
−32.6 [34]
−44.0 [9]
10.60
17.90
8.30
9.80
6.00
1
NMR (400 MHz, CDCl3) l 2.5 (s, H17, 3H), 6.7 (dd,
3
3JHꢀH 7.4 Hz, JHꢀP 3.8 Hz, H6, 1H), 7.0 (m, H5, 1H),
P(antr)3
3
7.3 (m, H3, H4, H8 and H9, 6H), 7.4 (t, JHꢀH 7.7 Hz,
3
H13, 2H), 7.5 (t, JHꢀH 7.4 Hz, H12, 2), 7.9 (m, H10 and
3
Table 5
H11, 4H), 8.5 (dd, JHꢀH 8.0 Hz, H14, 2H). 13C{1H}-
Comparison of measured and calculated 31P-NMR shifts of prepared
ligands
4
NMR (50 MHz, CDCl3) l 17.1 (d, JCꢀP 10.2 Hz, C17,
1C), 125.3 (s, C5, 1C), 125.7 (s, C9, 2C), 126.0 (s, C12,
2C), 126.2 (s, C14, 2C), 126.3 (s, C13, 2C), 126.4 (s, C10,
2C), 126.7 (s, C3, 1C), 128.6 (s, C4, 1C), 129.5 (s, C11,
2C), 129.6 (s, C8, 2C), 132.8 (s, C6, 1C), 133.5 (s, C15,
Ligand
Measured shift
(l, ppm)
Calculated shift
(l, ppm)
1
3 (SPanthr2)
4 (SPnaf2)
−38.4
−29.7
−13.9
−34.1
−40.4
−31.9
−15.3
−30.0
−39.40
−31.80
−15.60
−34.80
−41.70
−34.10
−17.90
−32.50
2C), 134.5 (s, C16, 2C), 134.9 (d, JCꢀP 7.3 Hz, C1, 1C),
135.7 (d, 1JCꢀP 23.2 Hz, C7, 2C), 144.3 (d, 2JCꢀP 29.1 Hz,
C2, 1C). 31P{1H}-NMR (162 MHz, CDCl3) l −29.7
(s). MS [M+1] Anal. Calc. for C27H22PS, 409.118;
found, 409.114.
5 (oSpSSP)
6 (oSoOOP)
7 (OPanthr2)
8 (OPnaf2)
9 (oOpSSP)
10 (oOoSSP)
2.3.3. (2-Thiomethylphenyl)bis(4-thiomethylphenyl)-
phosphine (oSpSSP) (5)
Yield 0.2 g, 0.5 mmol, 40.4%. m.p. 113–115°C. H-
1
(d, JCꢀP 22.4 Hz, C2, 1C). 31P{1H}-NMR (162 MHz,
CDCl3) l 164.6 (s). Anal. Calc. for C7H7Cl2OP: C, 40.2;
H, 3.4. Found: C, 40.7; H, 3.4%.
NMR (400 MHz, CDCl3) l 2.4 (s, H11, 3H), 2.5 (s, H12,
2
3
3
6H), 6.8 (dd, JHꢀH 7.8 Hz, JHꢀP 3.9 Hz, H6, 1H), 7.1
(m, H5, 1H), 7.2 (m, H8 and H9, 8H), 7.3 (m, H3 and
H4, 2H). 13C{1H}-NMR (100 MHz, CDCl3) l 15.2 (s,
4
2.2. Syntheses of phosphine ligands
C12, 1C), 17.2 (d, JCꢀP 7.9 Hz, C11, 2C), 125.3 (s, C5,
2
1C), 126.0 (d, JCꢀP 6.7 Hz, C8, 4C), 126.5 (s, C3, 1C),
1
2.2.1. General method
129.3 (s, C4, 1C), 132.1 (d, JCꢀP 9.2 Hz, C7, 2C), 133.0
3
The organic reagent containing bromine group was
lithiated by n-butyl lithium in sodium-dried diethyl
ether at 0°C. The mixture was stirred for 1–2 h at 0°C,
(s, C6, 1C), 134.3 (d, JCꢀP 20.4 Hz, C9, 4C), 136.7 (d,
1JCꢀP 10.0 Hz, C1, 1C), 139.9 (s, C10, 2C), 143.5 (d,
2JCꢀP 27.4 Hz, C2, 1C). 31P{1H}-NMR (162 MHz,

R.H. Laitinen et al. / Journal of Organometallic Chemistry 598 (2000) 235–242
239
CDCl3) l −13.9 (s). MS [M+1] Anal. Calc. for
C21H22PS3, 401.062; found, 401.059.
2.3.7. (2-Methoxyphenyl)bis(4-thiomethylphenyl)-
phosphine (oOpSSP) (9)
1
Yield 0.4 g, 1.0 mmol, 71.6%. m.p. 103–106°C. H-
2.3.4. (2-Thiomethylphenyl)bis(2-methoxyphenyl)-
phosphine (oSoOOP) (6)
Yield 0.3 g, 0.8 mmol, 62.2%. m.p. 180–182°C. H-
NMR (400 MHz, CDCl3) l 2.5 (s, H12, 6H), 3.8 (s, H11,
3
3
3H), 6.7 (dd, JHꢀH 7.6 Hz, JHꢀP 4.8 Hz, H6, 1H), 6.9
(m, H3 and H5, 2H), 7.2 (m, H8 and H9, 8H), 7.3 (t,
3JHꢀH 8.6 Hz, H4, 1H). 13C{1H}-NMR (100 MHz,
CDCl3) l 15.2 (s, C12, 2C), 55.7 (s, C11, 1C), 110.2 (s,
1
NMR (200 MHz, CDCl3) l 2.4 (s, H13, 3H), 3.7 (s, H14,
3
3
6H), 6.7 (m, H12, 2H), 6.8 (dd, JHꢀH 7.5 Hz, JHꢀP 3.8
Hz, H6, 1H), 6.9 (m, H9 and H11, 4H), 7.0 (m, H5, 1H),
7.3 (m, H3, H4 and H10, 4H). 13C{1H}-NMR (50 MHz,
1
C3, 1C), 121.0 (s, C5, 1C), 125.4 (d, JCꢀP 11.3 Hz, C1,
2
1C), 125.9 (d, JCꢀP 6.8 Hz, C8, 4C), 130.4 (s, C4, 1C),
4
1
CDCl3) l 17.4 (d, JCꢀP 10.2 Hz, C13, 1C), 55.7 (s, C14,
132.6 (d, JCꢀP 8.7 Hz, C7, 2C), 133.5 (s, C6, 1C), 134.2
1
3
2C), 110.3 (s, C9, 2C), 120.9 (s, C11, 2C), 124.4 (d, JCꢀP
(d, JCꢀP 20.6 Hz, C9, 4C), 139.5 (s, C10, 2C), 161.0 (d,
3
13.1 Hz, C7, 2C), 125.2 (s, C5, 1C), 126.8 (d, JCꢀP 2.9
2JCꢀP 15.1 Hz, C2, 1C). 31P{1H}-NMR (162 MHz,
CDCl3) l −15.3 (s). MS [M+1] Anal. Calc. for
C21H22OPS2, 385.085; found, 385.080.
Hz, C3, 1C), 130.0 (s, C4, 1C), 130.1 (s, C10, 2C), 133.3
1
(s, C6, 1C), 133.9 (s, C12, 2C), 136.4 (d, JCꢀP 10.2 Hz,
C1, 1C), 143.8 (d, 2JCꢀP 29.1 Hz, C2, 1C), 161.6 (d, 2JCꢀP
17.4 Hz, C8, 2C). 31P{1H}-NMR (162 MHz, CDCl3) l
−34.1 (s). MS [M+1] Anal. Calc. for C21H22O2PS,
369.108; found, 369.107.
2.3.8. (2-Methoxyphenyl)bis(2-thiomethylphenyl)-
phosphine (oOoSSP) (10)
Yield 0.4 g, 1.1 mmol, 47.0%. m.p. 156–159°C. H-
1
NMR (400 MHz, CDCl3) l 2.4 (s, H14, 6H), 3.8 (s, H13,
3
2.3.5. (2-Methoxyphenyl)bis(9-anthracenyl)phosphine
(OPanthr2) (7)
Yield 0.2 g, 0.4 mmol, 17.1%. m.p. 232–233°C. H-
3H), 6.6 (m, H6, 1H), 6.8 (d, JHꢀH 7.2 Hz, H12, 2H),
3
3
6.86 (t, JHꢀH 7.4 Hz, H3, 1H), 6.91 (d, JHꢀH 8.4 Hz,
H5, 1H), 7.0 (m, H11, 2H), 7.3 (m, H4, H9 and H10, 5H).
13C{1H}-NMR (100 MHz, CDCl3) l 17.4 (s, C14, 2C),
55.7 (s, C13, 1C), 110.3 (s, C3, 1C), 121.1 (s, C5, 1C),
124.0 (d, JCꢀP 12.6 Hz, C1, 1C), 125.2 (s, C11, 2C),
126.7 (s, C9, 2C), 129.2 (s, C10, 2C), 130.2 (s, C4, 1C),
1
NMR (200 MHz, CDCl3) l 3.4 (s, H15, 3H), 6.6–6.9
(m, H3, H5 and H6, 3H), 7.1 (m, H11, 4H), 7.3 (m, H4
3
1
and H10, 5H), 8.0 (d, JHꢀH 8.5 Hz, H12, 4H), 8.5 (s,
3
4
H14, 2H), 8.8 (dd, JHꢀH 8.9 Hz, JHꢀP 3.4 Hz, H9, 4H).
13C{1H}-NMR (100 MHz, CDCl3) l 55.3 (s, C15, 1C),
110.1 (s, C3, 1C), 121.1 (s, C5, 1C), 124.7 (s, C11, 4C),
1
133.4 (s, C12, 2C), 134.0 (s, C6, 1C), 135.9 (d, JCꢀP 9.2
2
Hz, C7, 2C), 144.0 (d, JCꢀP 29.3 Hz, C8, 2C), 161.6 (d,
1
125.7 (s, C10, 4C), 126.1 (d, JCꢀP 12.8 Hz, C1, 1C),
2JCꢀP 16.3 Hz, C2, 1C). 31P{1H}-NMR (162 MHz,
CDCl3) l −30.0 (s). MS [M+1] Anal. Calc. for
C21H22OPS2, 385.085; found, 385.081.
127.1 (s, C14, 2C), 127.3 (s, C9, 4C), 129.4 (s, C12, 4C),
129.8 (s, C4, 1C), 130.4 (s, C13, 4C), 131.5 (s, C8, 4C),
132.7 (s, C6, 1C), 135.5 (d, 1JCꢀP 14.0 Hz, C7, 2C), 161.4
2
(d, JCꢀP 18.5 Hz, C2, 1C) ppm. 31P{1H}-NMR (162
2.4. Crystallography
MHz, CDCl3) l −40.4 (s). MS [M+1] Anal. Calc. for
C35H26OP, 493.172; found, 493.173.
X-ray diffraction data were collected with a Nonius
KappaCCD (compounds 3, 4, 7, 8, and 9) or with a
Nonius Mach3 (compound 5) diffractometer using
2.3.6. (2-Methoxyphenyl)bis(1-naphthyl)phosphine
(OPnaf2) (8)
Yield 0.3 g, 0.8 mmol, 32.3%. m.p. 222–224°C. H-
,
Mo–Ka radiation (u=0.71073 A). For compound 5,
1
cell parameters were obtained from 25 automatically
NMR (400 MHz, CDCl3) l 3.8 (s, H17, 3H), 6.6 (dd,
centered reflections. Data collection (ꢀ/2q scan mode)
and cell refinement were carried out with the CAD4 EX-
3
3
3JHꢀH 7.6 Hz, JHꢀP 4.4 Hz, H6, 1H), 6.8 (t, JHꢀH 7.4
3
Hz, H5, 1H), 7.0 (m, H3 and H4, 2H), 7.3 (t, JHꢀH 7.6
PRESS diffractometer program [12] and data reduction
with XCAD4 program [13]. For other compounds the
data were collected using ƒ or combined ƒ/ꢀ scans
with a COLLECT [14] data collection program. Denzo
and Scalepack [15] programs were used for cell refine-
ments and data reduction. All structures were solved by
direct methods using SHELXS97 [16] or SIR97 [17] pro-
grams with the WINGX [18] graphical user interface or
by using SHELXTL version 5.1 [19] program package.
The structure refinements were carried out with the
SHELXL97 [20]. For compounds 3, 4, and 8, the hydro-
gens were constrained to ride on their parent atom
3
Hz, H9, 2H), 7.35 (t, JHꢀH 7.6 Hz, H8, 2H), 7.42 (t,
3
3JHꢀH 7.6 Hz, H13, 2H), 7.5 (t, JHꢀH 7.2 Hz, H12, 2H),
3
3
7.9 (dd, JHꢀH 8.2 Hz, H10 and H11, 4H), 8.5 (dd, JHꢀH
8.2 Hz, H14, 2H). 13C{1H}-NMR (50 MHz, CDCl3) l
55.8 (s, C17, 1C), 110.3 (s, C3, 1C), 121.2 (s, C5, 1C),
1
123.9 (d, JCꢀP 9.2 Hz, C1, 1C), 125.7 (s, C9, 2C), 125.9
(s, C12, 2C), 126.1 (s, C14, 2C), 126.3 (s, C13, 2C), 126.8
(s, C10, 2C), 128.5 (s, C11, 2C), 129.4 (s, C8, 2C), 130.5
2
(s, C4, 1C), 132.6 (s, C6, 1C), 133.4 (d, JCꢀP 10.2 Hz,
1
C15, 2C), 134.9 (s, C16, 2C), 135.7 (d, JCꢀP 23.2 Hz, C7,
2
2C), 161.7 (d, JCꢀP 17.2 Hz, C2, 1C). 31P{1H}-NMR
,
(162 MHz, CDCl3) l −31.9 (s). MS [M+1] Anal.
Calc. for C27H22OP, 393.141; found, 393.136.
(CꢀH=0.95 A, Uiso=1.2 (Ceq) for aromatic hydrogens
,
and CꢀH=0.98 A, Uiso=1.5 (Ceq) for methyl H

240
R.H. Laitinen et al. / Journal of Organometallic Chemistry 598 (2000) 235–242
atoms). For compounds 5 and 9 all hydrogens were lo-
cated from the difference Fourier map and refined
isotropically (compound 5: Uiso=0.05 for aromatic hy-
drogens, Uiso=0.08 for methyl hydrogens, compound 9:
these modifications will be studied in catalytic applica-
tions in the future. The schematic structures of prepared
phosphine ligands are shown in Scheme 2.
The Lewis basicity of the ligands reflects the electronic
effects of the substituents in the aromatic ring. Electron-
donating substituents such as alkyl groups increase the
basicity of ligands, while electron-withdrawing sub-
stituents such as aromatic groups with electronegative
substituents decrease it [22]. The basicity of the ligands
can be varied systematically by altering the substituents
on the phosphorus atom [23].
Uiso=0.04 for aromatic hydrogens, Uiso=0.05 for
methyl hydrogens). Crystallographic data are summa-
rized in Table 1 and selected bond lengths and angles in
Tables
2 and 3. The crystal structures of (2-
thiomethylphenyl)bis(9-anthracenyl)phosphine and (2-
methoxyphenyl)bis(4-thiomethylphenyl)phosphine are
shown in Figs. 1 and 2.
Basicities of phosphines have been measured by many
different methods. Simple titrations to measure pKa val-
ues of phosphines are difficult because the tertiary phos-
phines are typically insoluble in water. Nonaqueous
titrimetry [22,24], infrared technique [25], ultraviolet
photoelectron spectra [26] and NMR studies [27–29] are
the examples from the methods that have been used in
estimating the basicities of phosphines.
3. Results and discussion
3.1. Dichlorophosphines
In order to prepare ortho- and meta-substituted
aryldichlorophosphines, a method that utilizes a Grig-
nard reagent for activating the ortho or meta position in
the aromatic ring has been developed [11]. In this
method, the Grignard reagent of the ortho- or meta-sub-
stituted aryl group was transmetalated with ZnCl2 to the
corresponding organozinc halide reagent. This was then
allowed to react with PCl3 under THF in refluxing condi-
tions.
For the preparation of 1, the lithiation procedure in
combination with 20-fold excess of PCl3 was first exam-
ined. A dilute solution of 2-lithiothioanisole was added
dropwise to the ethereal solution of PCl3, after which the
mixture was refluxed. The reaction produced tris(2-
thiomethylphenyl)phosphine, instead of the title com-
pound. We therefore chose the combination of
organolithium and organozinc halide reagents in diethyl
ether for the preparation of a reagent, which was then al-
lowed to react with PCl3 (Scheme 1). The main improve-
ment compared with the original method [11] was the
formation of compounds 1 and 2 without side products.
4-Chlorobutanol forms when the aryl lithium com-
pound is refluxed in THF with ZnCl2 [21]. In order to
prevent the formation of this side product, diethyl ether
was used as a solvent. n-Butyl lithium was used instead
of magnesium, because the formation of the Grignard
reagent in diethyl ether was very slow. The target com-
pounds were separated by distillation in reduced pres-
sure.
31P-NMR is an important tool to get information
from the chemical nature of the phosphorus atom. The
31P-NMR chemical shifts have been shown to be depen-
dent on the R groups of a phosphine PR3 [30,31]. The
chemical shifts of tertiary phosphine ligands can be esti-
mated by an empirical equation [30]:
3
l= −62 % |Pn
(1)
n=1
where |P values are increments that are characteristic for
each substituent group. The reference value represents
PMe3 (l −62 ppm vs. 85% H3PO4).
The increments (|P) for the different substituent
groups used in constructing the new tertiary phosphine
ligands reported in this paper can be calculated from the
31P-NMR chemical shifts reported in the literature
(Table 4). In these ligands, all three substituent groups
are the same. When these increments were used to calcu-
late 31P-NMR chemical shifts for the new ligands, rela-
tively good agreement was obtained with the
experimental values (Table 5). These values indicate
that, having information of the substituent increments,
the environment of the phosphorus atom can be esti-
mated with reasonable accuracy.
It has been postulated that there is no general correla-
tion between basicity and 31P-NMR chemical shifts of
the phosphine ligands [29,35]. Instead, the basicity of
phosphines has been shown to be directly related to the
31P-NMR chemical shifts of corresponding phosphine
oxides [36]. Evidently within certain chemically related
groups of phosphines, a relationships can also be found
between the 31P-NMR shifts and basicity. We have pre-
viously [37] prepared a group of tertiary phosphine lig-
ands derived from 4-anisyl- and 4-thioanisyldichloro-
phosphines. The 31P-NMR chemical shifts of these lig-
ands were connected to the basicities determined by the
IR frequencies of the carbonyl groups in Ni(CO)3(PR3)
[23].
3.2. Tertiary phosphine ligands
2-Thioanisyl- and 2-anisyldichlorophosphines were
used as starting materials in the preparation of new ter-
tiary phosphine ligands. In these reactions the chlorides
were replaced by 2-thioanisyl, 4-thioanisyl, 2-anisyl, 1-
naphthyl and 9-anthracenyl groups in order to find a
variation in the steric and electronic properties of 2-
thioanisyl and 2-anisyl containing ligands. The effects of

R.H. Laitinen et al. / Journal of Organometallic Chemistry 598 (2000) 235–242
[2] A. Michaelis, Justis Liebigs Ann. Chem. 293 (1896) 248.
241
Large aromatic groups are known to have relatively
low basicities [22]. The low frequency of the 31P-NMR
chemical shifts of phosphines containing naphthyl and
anthracenyl groups agree with this. Correspondingly,
phosphine ligands having anisyl substituents bound to
phosphorus atom are more basic [23]. The same behav-
ior can also be connected to thioanisyl-substituted
phosphine ligands. The experimental and calculated
31P-NMR chemical shifts of the ligands prepared in this
work are in good agreement with the common trend
described before.
Bidentate ligands are catalytically promising and for
example, diphosphines are commonly used in homoge-
neous metal catalysts. Experimental results show that
the phosphine ligands containing 2-thiomethyl groups
behave typically as a bidentate ligands in metal com-
plexes [38]. The behavior of 2-methoxyphenyl phos-
phine ligands depends on the nature of the metal center
used in the complexes. With Cr, Mo, W, Rh and Ir,
2-methoxyphenyl-substituted ligands behave mainly as
a monodentate ligands [39,40]. With molybdenum the
coordination can also be fluxional [41]. In these kinds
of hemilabile complexes, the phosphorus atom is bound
strongly to a transition metal, while the oxygen atom
may be coordinatively labile. The oxygen can dissociate
from the metal allowing the formation of a free coordi-
nation site, which may be important in homogeneous
catalysis [42]. Heterodonor atoms in the para position
of aromatic rings do not take part in metal coordina-
tion. Their effect on the ligands is mainly electronic.
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4. Supplementary data
Crystallographic data for the structural analysis have
been deposited with the Cambridge Crystallographic
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pounds 3–5 and 7–9. Copies of this information may
be obtained free of charge from The Director, CCDC,
12, Union Road, Cambridge CB2 1EZ, UK (Fax:
+44-1223-336033 or e-mail: deposit@ccdc.cam.ac.uk
or http://www.ccdc.cam.ac.uk).
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Acknowledgements
The authors wish to thank The National Technology
Agency (Tekes) and Neste Chemicals for funding this
research.
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