Unexpected differences in reactivity between tin and lead organyl chlorides - Crystal structures of their organylphosphonium salts

Article abstract of DOI:10.1016/S0020-1693(03)00365-7

Pentacoordinated tin is known since the late 1950s but little is known about the ability of lead to form similar structures. Originally we investigated the reaction between a number of tetraorganylphosphonium chlorides [PR₄]⁺Cl^- (R=Me, Buⁿ, and Ph) and several diorganyltin dichlorides SnR′₂Cl₂ (R′=Me, Et, Prⁿ, Buⁿ, Ph, o-, m-, p-Tol) between 100 and 240°C. Novel pentacoordinated tin complexes, tetraorganylphosphonium diorganyltrichlorostannates [PR₄] [SnR′₂Cl₃] (1-19), were formed in good to excellent yields. In a second step, this synthetic approach was extended to include the reaction of diphenyllead dichloride Ph₂PbCl₂ with [PR ₄]⁺Cl^- (R=Buⁿ, Ph). Surprisingly, a two chloride transfer was observed to form the hexacoordinated lead species [PBu₄ⁿ]₂[PbPh₂Cl₄] (20). Under similar conditions, the pentacoordinated [PPh₄][PbPh ₃Cl₂] (21) was obtained by a phenyl transfer. Complexes 20 and 21 were characterised by NMR (¹H, ¹³C, ³¹P, and ²⁰⁷Pb), IR, MS, and X-ray crystallography. The anion of 20 assumes a lightly distorted octahedral geometry with the phenyl substituents in trans-positions. In the anion of 21 the phenyl substituents occupy the equatorial positions of a lightly distorted trigonal bipyramid. A thorough spectroscopical investigation of the tin complexes 1-19, including X-ray structural studies, which were possible for complexes with R′=aryl, revealed that these complexes are monomeric with a distorted trigonal bipyramidal [SnR′₂Cl₃]^- anion. Both aryl groups occupy equatorial positions.

Full text of DOI:10.1016/S0020-1693(03)00365-7

Inorganica Chimica Acta 357 (2004) 125–134
www.elsevier.com/locate/ica
Unexpected differences in reactivity between tin and lead
organyl chlorides – crystal structures of their
organylphosphonium salts q
a,
b,1
c
b
Dirk Weber *, Sven H. Hausner , Axel Eisengraber-Pabst , Sanghee Yun ,
€
b
Jeanette A. Krause-Bauer , Hans Zimmer
b,2
a
Institut f€ur Organische Chemie und Biochemie, Technische Universit€at M€unchen, Lichtenbergstr. 4, Garching 85747, Germany
Department of Chemistry, University of Cincinnati, ML 0172, Cincinnati, OH 45221-0172, USA
b
c
Fakult€at Chemie, Universit€at Stuttgart, Pfaffenwaldring 55, Stuttgart D-70569, Germany
Received 14 May 2003; accepted 24 May 2003
Abstract
Pentacoordinated tin is known since the late 1950s but little is known about the ability of lead to form similar structures.
Originally we investigated the reaction between a number of tetraorganylphosphonium chlorides [PR4]þClꢀ (R ¼ Me, Bun, and Ph)
and several diorganyltin dichlorides SnR02Cl2 (R0 ¼ Me, Et, Prn, Bun, Ph, o-, m-, p-Tol) between 100 and 240 °C. Novel pentaco-
ordinated tin complexes, tetraorganylphosphonium diorganyltrichlorostannates [PR4][SnR02Cl3] (1–19), were formed in good to
excellent yields. In a second step, this synthetic approach was extended to include the reaction of diphenyllead dichloride Ph2PbCl2
with [PR4]þClꢀ (R ¼ Bun, Ph). Surprisingly, a two chloride transfer was observed to form the hexacoordinated lead species
[PBun4]2[PbPh2Cl4] (20). Under similar conditions, the pentacoordinated [PPh4][PbPh3Cl2] (21) was obtained by a phenyl transfer.
Complexes 20 and 21 were characterised by NMR (1H, 13C, 31P, and 207Pb), IR, MS, and X-ray crystallography. The anion of 20
assumes a lightly distorted octahedral geometry with the phenyl substituents in trans-positions. In the anion of 21 the phenyl
substituents occupy the equatorial positions of a lightly distorted trigonal bipyramid. A thorough spectroscopical investigation of
the tin complexes 1–19, including X-ray structural studies, which were possible for complexes with R0 ¼ aryl, revealed that these
complexes are monomeric with a distorted trigonal bipyramidal [SnR02Cl3]ꢀ anion. Both aryl groups occupy equatorial positions.
Ó 2003 Elsevier B.V. All rights reserved.
Keywords: Pentacoordinated tin; Hexacoordinated lead; Pentacoordinated lead; Phenyl transfer
1. Introduction
spectroscopy, conductivity measurements, IR and solid-
state NMR spectroscopy have been reported (for a re-
view see for example [3]). Besides their importance for
stereochemical models and for the determination of cat-
ion–anion interactions, these studies may be useful for
the understanding of the intermediate state of nucleo-
philic substitution reactions such as the Stille coupling
during which the tin atom has been proposed to be
pentacoordinated [4].
Although organotin has been studied extensively, there
is a striking lack of data in the literature concerning or-
ganolead compounds. Little is known about the behav-
iour of lead in comparable reactions to tin or the ability to
form similar structures. Despite their toxicity handicap,
organolead compounds may have a greater potential for
Structures of pentacoordinated organotin compounds
are known since the late 1950s [1,2]. Since then, numerous
structural investigations on monomeric, dimeric, oligo-
or even polymeric pentacoordinate tin species employing
€
such different techniques as X-ray diffraction, Mossbauer
q Supplementary data associated with this article can be found, in the
online version, at doi:10.1016/S0020-1693(03)00365-7.
* Corresponding author. Tel.: +49-89-36037682; fax: +49-7531-
8493514.
E-mail address: dirk.weber1974@web.de (D. Weber).
Present address: School of Medicine, Yale University, VA Medical
1
Center/116A2, 950 Campbell Ave, West Haven, CT 06516, USA.
2
Deceased.
0020-1693/$ - see front matter Ó 2003 Elsevier B.V. All rights reserved.
doi:10.1016/S0020-1693(03)00365-7

126
D. Weber et al. / Inorganica Chimica Acta 357 (2004) 125–134
organic synthesis than currently recognised. One impor-
tant step towards tailored applications is to elaborate the
general differences concerning structure and reactivity in
comparison to tin. Therefore our effort was directed to-
wards a comparison of the behaviour of these two metals
in a relatively simple reaction setup. In this paper we de-
scribe the discovery of interesting differences concerning
the reactivity of these two metals.
tyl)phosphonium chloride was obtained from Fluka
(Buchs, Switzerland). Diphenyllead dichloride and all
diorganyltin dichlorides, except dimethyltin dichloride,
were prepared in two steps by published methods [15].
Dimethyltin dichloride was provided by Morton Inter-
national Incorporation (Cincinnati, OH). Reactions
were carried out under an inert gas atmosphere (N2 or
Ar).
Our interest in organotin, as well as organophospho-
nium chemistry, originally led us to investigate the reac-
tion between tetraorganylphosphonium chlorides and
dialkyltin dichlorides. In contrast to other experimental
conditions described for the reaction between diorganyl-
tin dichlorides and various salts [5–10] we simply com-
bined the dialkyltin dichloride with an equimolar amount
of the appropriate tetraorganylphosphonium chloride
without employing any solvent [11]. Initially, we prepared
the alkyl complexes [PR4][SnR02Cl3] (1)–(7) and (12)–(15)
(R0 ¼ Me, Et, Prn, Bun) [12]. For the complexes obtained
we tentatively proposed, based on NMR studies, a tri-
gonal bipyramidal structure [SnR02Cl3]ꢀ. We rationalised
that, by further limiting the degree of flexibility of the R0
residues, we would obtain more crystalline structures,
suitable for X-ray crystal analysis. It has been proposed
that, for complexes [SnR20 Cl3]ꢀ, the stability decreases in
the order R0 ¼ Ph > Me > Et > Pr because of the de-
creasing electronegative character of these groups [6].
Based on this information, and because of the easy syn-
thetic access, we decided to prepare the corresponding
complexes with R0 ¼ aryl [13]. As a part of our work on
pentacoordinated tin anions bearing a tetraorganylphos-
phonium counterion, we here present the crystal struc-
tures of [PBun4][SnPh2Cl3] (8), [PBu4n][Sn(o-Tol)2Cl3] (9),
[PPh4][SnPh2Cl3] (16), [PPh4][Sn(o-Tol)2Cl3] (17), [PPh4]
[Sn(m-Tol)2Cl3] (18), and [PPh4][Sn(p-Tol)2Cl3] (19).
The geometry and coordination of complexes 8, 9,
and 16–19 are discussed. On the basis of a detailed
207Pb NMR spectra were recorded on a Bruker AC
250 spectrometer. The broad range of 207Pb NMR shifts
of about 16,000 ppm required acquisition at various
frequencies [16–18]. The maximum shift-window size on
the spectrometer used was 100,000 Hz (equivalent to
about 1900 ppm). The signals of the lead complexes 20
and 21 were recorded in windows centred at 52.330,
52.320, and 52.280 MHz. Each signals was confirmed at
the three different frequencies to insure that the signal
3
seen is a real peak and not a ‘‘fold over’’ signal. Fur-
ther details, as well as NMR and IR experimental details
are summarised in the supplementary material.
2.2. Preparations
2.2.1. Tetraorganylphosphonium diorganyltrichlorostan-
nates [PR4][SnR02Cl3] (1–19). General procedure
Equimolar amounts, ranging between 0.8 and 2
mmol, of tetraorganylphosphonium chloride and the
corresponding diorganyltin dichloride were heated until
a homogeneous liquid was obtained (Table 1). The
crude product (except for complexes 10 and 11) was
recrystallised (Table 1). For complexes 8, 9, and 16–19
the slightly cloudy solution was pressed through a sy-
ringe microfilter. Slow evaporation of the solvent at
room temperature yielded crystals suitable for X-ray
analysis. Analytical and physical data are listed in
Tables 2 and 3.
1
characterisation by means of H-, 13C-, 31P-, and 119Sn-
2.2.2. Di[tetra(n-butyl)phosphonium] diphenyltetrachlo-
roplumbate [PBun4]2[PbPh2Cl4] (20)
NMR spectroscopy their structures are compared with
those of complexes 1–7 and 12–15.
Diphenyllead dichloride (865 mg, 2.00 mmol) and
tetra(n-butyl)phosphonium chloride (590 mg, 2.00
mmol) were heated to 180 °C for 1 h. The melt was
cooled to room temperature, dissolved in hot ethanol,
and filtered cold (syringe microfilter). Removal of the
solvent in a rotary evaporator yielded brownish, waxy
crystals. More impurities were removed with three times
50 ml of refluxing ether. A colourless, crystalline prod-
uct (810 mg, 0.80 mmol, 80% o. Th.) was obtained after
recrystallising twice from a small amount of THF
Furthermore, the extension of this synthetic approach
to include the reaction of diphenyllead dichloride
Ph2PbCl2 with [PR4]þClꢀ (R ¼ Bun, Ph) is presented [14].
Unexpectedly, the formation of complexes [PBun4]2
[PbPh2Cl4] (20) and [PPh4][PbPh3Cl2] (21) was observed.
Their structures and structural differences to the afore-
mentioned tin complexes, obtained from the corre-
sponding reactions, will be discussed based on
spectroscopic and crystallographic data.
2. Experimental
3
The standard frequency for 207Pb NMR spectra is the exact
frequency determined for Pb(CH3)4 (d ꢁ 0 ppm). Pb(CH3)4 has
historically been used as a standard, but nowadays is avoided because
of its toxicity and volatility. The standard frequency is defined as
‘‘20,920,597/100,000,000 times the frequency of SiMe4’’ [16,17]. For
the 250.133000 MHz instrument used, it is 52.329317 MHz.
2.1. Materials
Unless stated otherwise, all chemicals were purchased
from Aldrich Chemical (Milwaukee, WI). Tetra(n-bu-

D. Weber et al. / Inorganica Chimica Acta 357 (2004) 125–134
127
Table 1
Reaction conditions for complexes 1–19
Complex
T (°C)
t (min)
Recrystallisation solvent
[PMe4][SnMe2Cl3] (1)
[PMe4][SnEt2Cl3] (2)
[PMe4][SnPrn2Cl3] (3)
[PBun4][SnMe2Cl3] (4)
[PBun4][SnEt2Cl3] (5)
200
200
180
110
100
100
100
120
120
140
130
200
200
200
200
230
230
220
220
240
180
120
60
EtOH
EtOH
EtOH
Et2O
60
Et2O:EtOH ¼ 7:1
[PBun4][SnPr2nCl3] (6)
120
120
60
Et2O
Et2O:EtOH ¼ 19:1
Et2O:acetone:CH3CN ¼ 45:2:few drops
[PBun4][SnBu2nCl3] (7)
[PBun4][SnPh2Cl3] (8)
[PBun4][Sn(o-Tol)2Cl3] (9)
[PBun4][Sn(m-Tol)2Cl3] (10)
[PBun4][Sn(p-Tol)2Cl3] (11)
[PPh4][SnMe2Cl3] (12)
[PPh4][SnEt2Cl3] (13)
[PPh4][SnPrn2Cl3] (14)
[PPh4][SnBun2Cl3] (15)
[PPh4][SnPh2Cl3] (16)
[PPh4][Sn(o-Tol)2Cl3] (17)
[PPh4][Sn(m-Tol)2Cl3] (18)
[PPh4][Sn(p-Tol)2Cl3] (19)
60
60
Et2O:EtOH ¼ 1:1
a
a
60
180
180
240
240
30
EtOH
EtOH
EtOH
EtOH
EtOH
EtOH
EtOH
EtOH
30
30
30
a Oil. Compound did not crystallise.
(Table 4). Crystals suitable for X-ray crystallography
were obtained by slow evaporation of the THF at room
temperature.
combined in a 100 ml round bottom flask and placed
onto a preheated oilbath (260–265 °C). The mixture was
stirred until a thin melt was obtained and kept at this
temperature for one additional minute. The mixture was
removed from the oilbath and cooled to below 200 °C.
The bath was allowed to cool, and the mixture was
stirred for an additional one half hour at 205–215 °C.
The mixture solidified readily upon cooling to room
2.2.3. Tetraphenylphosphonium triphenyldichloroplum-
bate [PPh4][PbPh3Cl2] (21)
Diphenyllead dichloride (2.50 g, 5.78 mmol) and 2.17
g (5.78 mmol) tetraphenylphosphonium chloride were
Table 2
Analytical and physical data for tetraorganylphosphonium diorganyltrichlorostannates
Complex
Mp (°C)
Appearance
Yieldb (%)
Analysis (%)e
C
H
Cl
[PMe4][SnMe2Cl3] (1)
[PMe4][SnEt2Cl3] (2)
[PMe4][SnPrn2Cl3] (3)
[PBun4][SnMe2Cl3] (4)
[PBun4][SnEt2Cl3] (5)
>300a
>280a
260a
colourless powder
colourless powder
colourless powder
colourless plates
colourless plates
colourless plates
colourless plates
colourless crystals
colourless crystals
colourless oil
66
72
21.02 (20.81)
25.45 (25.67)
30.03 (29.85)
42.20 (42.02)
44.09 (44.27)
46.49 (46.30)
48.33 (48.15)
53.00 (52.66)
54.32 (54.05)
54.20 (54.05)
53.89 (54.05)
52.30 (52.53)
53.93 (54.02)
54.95 (55.38)
56.69 (56.63)
59.94 (60.17)
61.25 (61.13)
60.91 (61.13)
61.23 (61.13)
5.32 (5.24)
5.67 (5.92)
6.39 (6.51)
8.19 (8.23)
8.35 (8.55)
8.61 (8.83)
8.97 (9.09)
7.15 (7.25)
7.70 (7.55)
7.55 (7.55)
7.38 (7.55)
4.39 (4.41)
4.98 (4.86)
5.24 (5.27)
5.58 (5.64)
4.19 (4.20)
4.61 (4.59)
4.36 (4.59)
4.40 (4.59)
30.53 (30.72)
28.06 (28.42)
26.27 (26.43)
20.81 (20.67)
19.46 (19.60)
18.46 (18.64)
88
82
92–93
80–81
92–93
79–81
64–66
95–96
81
96
[PBun4][SnPr2nCl3] (6)
[PBun4][SnBu2nCl3] (7)
[PBun4][SnPh2Cl3] (8)
[PBun4][Sn(o-Tol)2Cl3] (9)
[PBun4][Sn(m-Tol)2Cl3] (10)
[PBun4][Sn(p-Tol)2Cl3] (11)
[PPh4][SnMe2Cl3] (12)
[PPh4][SnEt2Cl3] (13)
[PPh4][SnPrn2Cl3] (14)
[PPh4][SnBun2Cl3] (15)
[PPh4][SnPh2Cl3] (16)
[PPh4][Sn(o-Tol)2Cl3] (17)
[PPh4][Sn(m-Tol)2Cl3] (18)
[PPh4][Sn(p-Tol)2Cl3] (19)
91
17.50 (17.76)
f
92
24c
quant.d
quant.d
83
f
f
f
colourless oil
197–198
177–178
130–131
109–110
230–233
230
colourless powder
colourless powder
colourless powder
colourless powder
colourless crystals
brownish crystals
brownish crystals
brownish crystals
17.76 (17.89)
17.23 (17.08)
15.89 (16.35)
83
90
92
15.80 (15.67)
f
34c
57c
70c
31c
f
f
f
149–150
153–154
a Decomposition.
b Based on tin.
c Yield not optimised.
d Compound could not be recrystallised.
e Calculated values in parentheses.
f Not determined.

128
D. Weber et al. / Inorganica Chimica Acta 357 (2004) 125–134
Table 3
31P- and 119Sn NMR data for tetraorganylphosphonium diorganyl-trichlorostannates (complexes 1–19) and some starting materialsa
Compound
31Pb
119Sn
DMSO-d6
CDCl3
MeOH-d3
SnMe2Cl2
SnEt2Cl2
)249.9d
)225.7
)218.3
)211.6
141.5
128.3
126.3
126.5
)27.2
)25.4
)21.7
SnPrnCl2
SnBunCl2
SnPh2Cl2
Sn(m-Tol)2Cl2
Sn(p-Tol)2Cl2
[PBun4]Cl
[PPh4]Cl
33.7
23.6
d;e
d;e
d;e
[PMe4][SnMe2Cl3] (1)
[PMe4][SnEt2Cl3] (2)
[PMe4][SnPrn2Cl3] (3)
[PBun4][SnMe2Cl3] (4)
[PBun4][SnEt2Cl3] (5)
[PBun4][SnPr2nCl3] (6)
[PBun4][SnBu2nCl3] (7)
[PBun4][SnPh2Cl3] (8)
[PBun4][Sn(o-Tol)2Cl3] (9)
[PBun4][Sn(m-Tol)2Cl3] (10)
[PBun4][Sn(p-Tol)2Cl3] (11)
[PPh4][SnMe2Cl3] (12)
[PPh4][SnEt2Cl3] (13)
[PPh4][SnPrn2Cl3] (14)
[PPh4][SnBun2Cl3] (15)
[PPh4][SnPh2Cl3] (16)
[PPh4][Sn(o-Tol)2Cl3] (17)
[PPh4][Sn(m-Tol)2Cl3] (18)
[PPh4][Sn(p-Tol)2Cl3] (19)
26.16c
26.53c
24.17
33.54
33.54
33.54
33.49
34.91c
34.90c
34.86c
34.89c
23.80
23.81
23.81
23.81
23.46c
23.51c
23.46c
23.45c
)246.7
)226.4
)206.4
)92.9
)98.9
)58.7
)98.7
)96.1
)106.2
)99.6
)248.2
)238.4
)247.3
)387.7
)270.6
)384.6
)375.2
)243.4
)221.4
)195.9
)193.8
)387.2
)276.0
)381.0
)375.3
)238.9
d;e
)103.3
)112.0
)114.0
d;e
d;e
)249.7d
)240.5d
a Chemical shift (d) in ppm.
b Spectra in CDCl3 unless otherwise stated.
c Spectrum in DMSO-d6.
d Low solubility.
e Unable to determine.
temperature. It was extracted with 125 ml hot ethanol in
several portions, followed by filtration (syringe micro-
filter). Removal of the solvent in a rotary evaporator
yielded a partially viscous, light-brownish solid. It so-
lidified upon addition of 150 ml water. The mixture was
briefly treated with ultrasound, and the solid was al-
lowed to settle overnight. The liquid was removed, and
the treatment was repeated with another 150 ml water.
The lightly cream coloured solid was dried under re-
duced pressure. It was taken up in 150 ml THF, briefly
heated to reflux, ultrasonicated, and filtered warm (sy-
ringe microfilter). The solvent was removed in a rotary
evaporator. Remaining impurities in the resulting resin
were extracted with three times 1–5 ml refluxing THF.
After drying, 0.78 g (0.919 mmol, 16% o. Th.) colour-
less, fine crystals were obtained (Table 4). Crystals
suitable for X-ray crystallography were obtained by
slow evaporation of the THF at room temperature.
paratone-N and mounted on glass fibers. Data for
[PPh4][SnPh2Cl3] (16) and [PPh4][Sn(p-Tol)2Cl3] (19)
were collected at room temperature on a Siemens P3
4
diffractometer with graphite-monochromated Mo Ka
radiation. Lattice parameters were obtained from the
angular settings from 40 reflections lying in a 2h range of
10–30°. Intensity data were collected using variable
speed h ꢀ 2h scans out to 55° in 2h. All data were cor-
rected for decay (based on three standard reflections),
Lorentz and polarisation effects as well as for absorption
(based on measured w scans) [19].
Data for [PBu4][Sn(o-Tol)2Cl3] (9), [PPh4][Sn(o-
Tol)2Cl3] (17), [PPh4][Sn(m-Tol)2Cl3] (18), and
[PBu4]2[PbPh2Cl4] (20) were collected at low tempera-
ture on a standard Siemens SMART 1K CCD diffrac-
4
tometer
radiation and a detector distance of 5.0 cm. Data for
with graphite-monochromated Mo Ka
4
For the CCD diffractometer, SMART v4.05, v5.054 or v5.622 and
2.3. X-Ray crystallographic analysis
SAINT v4.05, v5.A06 or v6.02A programs were used for data
collection and processing, respectively. The P3=P4-PC Diffractometer
Program v4.27 was used for data collection and reduction on the P3
diffractometer. Siemens Analytical X-ray Instruments, Madison, WI.
For X-ray examination and data collection, suitable
crystals were coated with a light film of epoxy resin or

D. Weber et al. / Inorganica Chimica Acta 357 (2004) 125–134
129
Table 4
Analytical and physical data for tetraorganylphosphonium organylchloroplumbates
Complex
[PBun4]2[PbPh2Cl4] (20)
[PPh4][PbPh3Cl2] (21)
Mp (°C)
166–168
colourless plates
212–214
colourless crystals
Appearance
Yielda (%)
Analysisb (%)
80
51.74 (51.71)c
8.14 (8.09)c
16
59.70 (59.43)
C
H
1H
4.39 (4.16)
7.26–7.36 (3H, m, Pb p-CH), 7.44 (6H, t, J 7.3,
4JPbH 21.0, Pb m-CH), 7.67–7.77 (8H, m, P o-CH),
7.77–7.85 (8H, m, P m-CH), 7.92–7.98 (4H, m, P p-
NMRd
0.90 (24H, t, J 6.9, PCH2CH2CH2CH3), 1.30–1.50
(32H, m, PCH2CH2CH2CH3), 2.10–2.30 (16H, m,
PCH2), 7.31 (2H, t, J 7.0, p-CH), 7.46 (4H, t, J 7.4,
4JPbH 20.7, m-CH), 8.34 (4H, d, J 7.9, JPbH 106.8,
3
4
CH), 8.20 (6H, d, J 7.3, JPbH 60.3, Pb o-CH)
o-CH)
1
1
13C
13.37 (PCH2CH2CH2CH3), 17.53 (d, JPC 46.7,
117.80 (d, JPC 90.7, PC), 128.22 (bs, Pb p-CH),
2
PCH2), 22.78 (d, JPC 4.9, PCH2CH2), 23.58
129.11(t,3JPbC 55.7, Pb m-CH), 130.56 (d, 3JPC 13.4,
P m-CH), 134.63 (d, 2JPC 10.6, P o-CH), 135.47 (bs,
P p-CH), 136.78 (t, JPbC 44.7, Pb o-CH), 162.09
(PbC)
(PCH2CH2CH2), 128.38 (p-CH), 128.60 (3JPbC
104.8, m-CH), 134.04 (2JPbC 63.5, o-CH), 173.91
(PbC)
2
31P
207Pb
34.68
)520
23.45 (1JPC 89.3, JPC 11.0)
2
)237
IRe (m/cmꢀ1
)
682 m, 735 m, 844 w, 906 m, 992 m, 1017 m, 1095 m,
1231 w, 1313 w, 1380 w, 1414 s, 1436 s, 1472 s,
1566 m, 2871 s, 2931 s, 2956 s, 3045 w
536 s, 689 s, 724 s, 757 m, 857 w, 996 m, 1015 w,
1059 w, 1109 s, 1185 w, 1314 w, 1434 s, 1474 m,
1483 m, 1568 m, 1586 w, 3048 m
a Isolated yield of pure product based on PbPh2Cl2, not optimised.
b Calculated values in parentheses.
c Calculated for [PBu4n]2[PbPh2Cl4].
d Chemical shift (d) in ppm, J values in Hz. Recorded in DMSO-d6. Assignments are based on data published in the literature (for 13C NMR of
phenyl lead complexes, see for example [22], for 13C NMR of phenylphosphonium salt complexes, see [25], for 1H NMR data of [PbPh3Cl2][NEt4],
see [23]) [24].
e Sample in pressed KBr pellet.
[PPh4][PbPh3Cl2] (21) was collected at room tempera-
ture. Data for [PBu4][SnPh2Cl3] (8) was collected at low
temperature on a standard Siemens SMART 2K CCD
diffractometer with graphite-monochromated Ag Ka
radiation and a crystal-to-detector distance of 3.9 cm.
Crystallographic data for complexes 8, 20, and 21 are
summarised in Table 5. Further details, as well as the
refinements for all solved structures, with the crystallo-
graphic agreement factors, are available in the supple-
mentary material.
Table 5
Crystal and refinement data for [PBun4][SnPh2Cl3] (8), [PBu4n]2[PbPh2Cl4] ꢂ THF (20), and [PPh4][PbPh3Cl2] (21) with estimated standard deviations in
parentheses
Compound
8
20
21
Formula
C
638.66
28H46Cl3PSn
C44H82Cl4P2Pb ꢂ C4H8O
1094.13
C42H35Cl2PPb
848.76
Formula weight
Crystal system
Space group
T (K)
orthorhombic
Pna21
150(2)
monoclinic
P21=n
150(2)
orthorhombic
Pbca
293(2)
0.71073
ꢀ
k (A)
0.56086
0.71073
ꢀ
a (A)
22.1430(4)
11.1633(2)
12.4882(2)
15.7749(7)
15.6298(7)
23.2054(10)
104.011(1)
5551.3(4)
4
17.984(3)
16.658(2)
24.147(3)
ꢀ
b (A)
ꢀ
c (A)
b (°)
V (A )
3
ꢀ
3086.95(9)
4
0.608
7234.0(18)
8
4.885
Z
l(Mo Ka) (mmꢀ1
)
3.320
57355
Collected reflections
Independent reflections
Rint
32141
7426
45441
8962
13672
0.0537
0.0686
0.0329
0.0482
0.0819
0.0339
0.1166
R1 [I > 2rðIÞ]
0.0340
0.0667
R1 (all data)

130
D. Weber et al. / Inorganica Chimica Acta 357 (2004) 125–134
3. Results and discussion
3.1. Diorganyltrichlorostannates
Clequatorial distortions from ideal trigonal bipyramidal
geometry can be attributed to repulsions of the aryl
groups in the equatorial plane and between the aryl
groups and the equatorial halide, respectively. One notes
that the C–Sn–C angles range from 134.7 to 143.5° for
the [PPh4]þ salts 16–19 and are 122.6° and 135.3°, re-
spectively, for the [PBu4n]þ salts 8 and 9, while the Cl(3)–
Sn–C angles range from 106.7° to 116.6° for the [PPh4]þ
salts and are 109.3° and 119.1°, respectively, for the
[PBun4]þ salts. The distortions appear to be dependent on
the overall steric bulk of the aryl group, as well as the
degree of non-coplanarity of the rings. Unlike the [SnR02
Cl3]ꢀ anions in complexes such as [dbttf][SnEt2Cl3] [10]
[C9H8N][SnMe2Cl3] [5] [Pt(S2N2H)(PEt3)][SnMe2Cl3]
[8], and [ttf][SnMe2Cl3] [9] which form loosely associated
3.1.1. Crystal structures of tetraorganylphosphonium
diaryltrichlorostannates (8, 9, and 16–19)
The crystal structures of 8, 9, and 16–19 consist of
isolated [PPh4]þ or [PBu4n]þ cations and [SnR02Cl3]ꢀ
(R0 ¼ Ph, o-Tol, m-Tol, p-Tol) anions. As a typical ex-
ample, an ORTEP view of complex 8 is shown in Fig. 1.
Selected bond distances and angles are given in Table 6.
For the structures reported here, the [SnR02Cl3]ꢀ anion
adopts a distorted trigonal bipyramidal geometry about
the central metal atom with both aryl groups occupying
equatorial positions. As observed for related [SnR02Cl3]ꢀ
trigonal bipyramidal species [5,7–10,20], the axial Sn–Cl
bond distances in complexes 8, 9, and 16–19 are 0.15–
ꢀ
dimers (Sn ꢂ ꢂ ꢂ Cl interactions of <4 A), the complexes
reported here are monomeric (Sn ꢂ ꢂ ꢂ Cl interactions of
ꢀ
ꢀ
>5 A), such as [Et4N][SnPh2Cl3] [7] and [Me2SnCl,
terpyridyl][SnMe2Cl3] [20].
0.21 A (6.3–8.9%) longer than the equatorial Sn–Cl
bond. This finding is consistent with the observation
that the difference between axial and equatorial lengths
increases markedly upon replacement of one or more of
five identical ligands with more electropositive groups in
a trigonal bipyramidal coordination [21]. The Sn–C
bond lengths in our complexes are similar to those
found in other trigonal bipyramidal tin complexes with
either alkyl or aryl groups. The C–Sn–C and C–Sn–
3.1.2. NMR data and structure of the tetraorganylphos-
phonium dialkyltrichlorostannates (1–7 and 12–15)
Although we were unable to obtain X-ray crystal
structures for the tin complexes [PR4][SnR02Cl3]
(R ¼ Me 1–3; Bun 4–7; Ph 12–15; R0 ¼ Me, Et, Prn, and
Bun), the analysis of the NMR data yielded distinct in-
formation about their structure. Comparing the 13C
chemical shift of CipsoSn (the carbon atom attached to
the Sn atom) between the precursors, namely SnPrn2Cl2,
SnBun2Cl2, SnPh2Cl2, and Sn(p-Tol)2Cl2, and complexes
6–8, 11, 14, and 15, it was found that there is a uniform
downfield shift of about 10–11 ppm (Table 7). This can
be explained by the transfer of a chlorine anion to the
central tin atom, which, in case of the complexes with
R0 ¼ aryl, was confirmed by X-ray crystallography. The
deshielding effect caused by the additional covalently
bound chlorine was found to be only effective for the
nearest carbon atom, changes for carbon atoms further
Table 7
Comparison of 13C chemical shifta of CipsoSn (the carbon atom at-
tached to the tin atom)
Fig. 1. ORTEP plot of complex 8. (Hydrogens have been omitted for
clarity.)
Compound
d
Ddb
SnPrn2Cl2
[PBun4][SnPr2nCl3] (6)
[PPh4][SnPrn2Cl3] (14)
29.03
39.37
39.16
10.34
10.13
Table 6
ꢀ
Selected bond lengths (A) and angles (°) for complex 8 with estimated
standard deviations in parentheses
SnBun2Cl2
[PBun4][SnBu2nCl3] (7)
[PPh4][SnBun2Cl3] (15)
26.83
36.92
36.96
10.09
10.13
Sn–Cl(1)
Sn–Cl(2)
Sn–Cl(3)
2.541(1)
2.523(1)
2.371(1)
Sn–C(17)
Sn–C(23)
2.152(3)
2.147(3)
SnPh2Cl2
[PBun4][SnPh2Cl3] (8)
136.95
148.09
11.14
10.83
Cl(1)–Sn–Cl(2)
Cl(1)–Sn–Cl(3)
Cl(2)–Sn–Cl(3)
C(23)–Sn–C(17)
Cl(1)–Sn–C(17)
175.56(3)
88.24(3)
87.35(3)
122.6(1)
91.30(9)
Cl(1)–Sn–C(23)
Cl(2)–Sn–C(17)
Cl(2)–Sn–C(23)
Cl(3)–Sn–C(17)
Cl(3)–Sn–C(23)
91.4(1)
91.3(1)
90.3(1)
Sn(p-tol)2Cl2
[PBun4][Sn(p-Tol)2Cl3] (11)
133.47
144.30
118.36(9)
119.08(9)
a Chemical shift (d) in ppm, spectra in CDCl3.
b Difference to the corresponding precursor.

D. Weber et al. / Inorganica Chimica Acta 357 (2004) 125–134
131
away were marginal. As shown in Table 3, 119Sn NMR
chemical shifts (in CDCl3) changed from about +125
ppm for the dialkyltin dichlorides SnR2Cl2 (R ¼ Et, Prn,
and Bun) to about )100 to )110 ppm for their products,
complexes 5–7 and 13–15. A similar change, i.e., about
)220 to )230 ppm, is observed when comparing the
diaryltin dichlorides SnR2Cl2 (R ¼ Ph, m-Tol, and p-
Tol) with their products, complexes 8, 10, 11, 18, and 19.
On the other hand, changes of the 119Sn NMR
chemical shifts in DMSO-d6 were found to be relatively
small (3–56 ppm) for the complexes studied. The reason
for this observation most probably lies in the enhanced
coordinating and polarising abilities of the solvent
DMSO, compared to CDCl3. The presence of this sol-
vent effect is supported by the observation that in-
creasing alkyl-chain lengths at the Sn atom correlate
with an increasing change of the 119Sn NMR chemical
shift. The methyl group in compound 1 showed with
Dd ¼ 3 ppm the smallest shielding of the Sn atom, the n-
butyl group in compound 15 with Dd ¼ 56 ppm the
greatest.
Fig. 2. ORTEP plot of complex 20. (Hydrogens and the THF molecule
have been omitted for clarity.)
31P NMR chemical shifts for the phosphonium ca-
tions remain almost unchanged by the complex salt
formation (Table 3), which is in agreement with previ-
ous studies [25].
In summary, 13C-, and 119Sn NMR data indicated
that the complex salt formation changed the chemical
environment of the tin atom for both, compounds with
R0 ¼ aryl and R0 ¼ alkyl. These results agree very well
with the structural insights obtained from the crystal
structures of complexes 8, 9, and 16–19 (Fig. 1, Tables 5
and 6).
Based on these data it can be concluded that for
complexes 1–7 and 12–15, for which no X-ray analysis
was possible, most likely, also a [SnR02Cl3]ꢀ anion with
distorted trigonal bipyramidal geometry was formed, as
well.
3.2. Phenylchloroplumbates
Fig. 3. ORTEP plot of complex 21. (Hydrogens have been omitted for
clarity.)
3.2.1. Synthesis
Compound 20, [PBu4n]2[PbPh2Cl4], was formed by the
same reaction seen for the tetraorganylphosphonium
dialkyltrichlorostannates 1–19, in which the chloride ion
formed a bond with the metal. In case of the tin com-
plexes, one chloride was transferred, whereas for 20, two
chlorides reacted with the metal (Fig. 2, Table 5). Given
the high yield of 20, the two-chloride transfer was the
preferred reaction of PbCl2Ph2 with [PBun4]þClꢀ. Con-
sidering the fact that the reaction conditions for this
reaction, heating a neat mixture to 180 °C, and for the
formation of many [SnCl3R2]ꢀ tin complexes are prac-
tically identical, it can be concluded that steric factors
play an important role.
260 °C for a short time in order to obtain a homoge-
neous melt. Prolonged heating at this temperature
resulted in significant decomposition (i.e., gas develop-
ment and the formation of some colourless, insoluble
solid). The isolated product, [PPh4][PbPh3Cl2] (21), did
not result from a chloride transfer to the metal (Fig. 3,
Table 5). Surprisingly, a phenyl transfer occurred in-
stead. Tetraphenylphosphonium ions are stable even at
5
relatively high temperatures. Phenyl lead compounds,
on the other hand, are known to undergo dispropor-
tionation reactions and phenyl transfers [15,26]. Based
5
The melting points of [PPh4]þClꢀ and [PPh4]þBrꢀ are 273–275 °C
As pointed out in the experimental section, the mix-
ture of [PPh4]þClꢀ and Ph2PbCl2 had to be heated to
and 295–298 °C, respectively.

132
D. Weber et al. / Inorganica Chimica Acta 357 (2004) 125–134
Table 8
on these facts, it is conceivable that 21 was formed from
Ph2PbCl2 in a phenyl transfer reaction. The relatively
low yield and the observed partial decomposition at the
high reaction temperature are consistent with the for-
ꢀ
Selected bond lengths (A) and angles (°) for complex 20 with estimated
standard deviations in parentheses
Pb–Cl(1)
Pb–Cl(2)
Pb–Cl(3)
Pb–Cl(4)
2.7140(9) Pb–C(33)
2.6968(9) Pb–C(39)
2.7392(9)
2.180(4)
2.179(9)
6
mation of a significant amount of by-products.
2.7386(9)
3.2.2. 207Pb NMR spectroscopy
Cl(1)–Pb–Cl(2)
Cl(1)–Pb–Cl(3)
Cl(1)–Pb–Cl(4)
Cl(1)–Pb–C(33)
Cl(1)–Pb–C(39)
Cl(2)–Pb–Cl(3)
Cl(2)–Pb–Cl(4)
Cl(2)–Pb–C(33)
Cl(2)–Pb–C(39)
90.99(3)
90.88(3)
179.00(3)
90.75(10)
90.96(9)
178.00(3)
88.01(3)
90.57(9)
91.43(9)
Cl(3)–Pb–Cl(4)
90.12(3)
88.68(10)
89.26(9)
þ
The 207Pb NMR shift of [PBun4]2 [PbCl4Ph2]2ꢀ (20)
Cl(3)–Pb–C(33)
Cl(3)–Pb–C(39)
Cl(4)–Pb–C(33)
Cl(4)–Pb–C(39)
C(33)–Pb–C(39)
was determined as d ¼ ꢀ520 (ꢃ 5) ppm; the shift of
[PPh4]þ[PbCl2Ph3]ꢀ (21) was observed at d ¼ ꢀ237 (ꢃ5)
ppm. Given the fact that the 207Pb NMR shift values
reflect the electron density at the metal [24] they indicate
moderate shielding of the metal nucleus. The shift values
fall in the range between those reported for PbPh4
89.16(10)
89.17(9)
177.35(13)
7
(d ꢄ ꢀ175 ppm) and for PbCl4 (d ¼ ꢀ768 ppm). In
fact, the shift of complex 20 is very close to the one of
the hexacoordinated metal in anhydrous PbPh2(OAc)2
(d ¼ ꢀ587 ppm) [27]. However, the dependence of the
207Pb NMR shift on temperature, interaction with the
solvent, and, to a lesser extend, concentration makes
the direct comparison of the shift values difficult.
Table 9
ꢀ
Selected bond lengths (A) and angles (°) for complex 21 with estimated
standard deviations in parentheses
Pb–Cl(1)
Pb–Cl(2)
2.7273(12) Pb–C(25)
2.7277(11) Pb–C(31)
Pb–C(37)
2.213(4)
2.221(4)
2.218(4)
3.2.3. Crystal structures
Cl(1)–Pb–Cl(2)
Cl(1)–Pb–C(25)
Cl(1)–Pb–C(31)
Cl(1)–Pb–C(37)
Cl(2)–Pb–C(25)
Cl(2)–Pb–C(31)
Cl(2)–Pb–C(37)
177.70(4)
C(25)–Pb–C(31)
C(25)–Pb–C(37)
C(31)–Pb–C(37)
121.84(15)
113.71(17)
124.39(15)
The tetraalkyl ammonium salts of [PbCl4Ph2]2ꢀ and
[PbCl2Ph3]ꢀ have been studied previously by means of
IR- and Raman spectroscopy [28]. Based on these re-
sults, essentially isolated anions had been predicted, but
there remained uncertainty about the precise structure
and possible weak interactions between the anions.
Fig. 2 depicts an ORTEP plot of 20. Selected bond
distances and angles are given in Table 8. In the crystal,
the [PbPh2Cl4]2ꢀ anion assumes a lightly distorted oc-
tahedral geometry. The phenyl groups occupy trans
positions. Compound 20 consists of isolated cations and
87.72(12)
88.86(12)
91.17(14)
90.74(12)
90.50(12)
91.01(13)
3.2.4. Mass spectroscopic studies
In the case of the lead complexes 20 and 21 we were
able to obtain mass spectra with a good S/N ratio and
an excellent correspondence of observed to calculated
isotope distribution.
ꢀ
anions. Based on the large distance of 6.890 A
þ
(Cl1 ꢂ ꢂ ꢂ Cl3) between neighbouring anions, the forma-
tion of Pb–Cl chains can be ruled out. The dihedral
angle between the planes of the phenyl groups is 85.4°.
The crystal used for X-ray crystallographic studies was
obtained from a THF solution by slow evaporation of
the solvent. This crystal contains a THF molecule in the
lattice.
The mass spectrum for [PBun4]2 [PbCl4Ph2]2ꢀ (20)
showed strong signals around m/z ¼ 1282. They are at-
þ
tributed to the cationic complex [PBun4]3 [PbCl4Ph2]2ꢀ
(calc. m/z ¼ 1281.53) (Fig. 4). Other prominent signals in
the MALDI-MS could be attributed to [PBun4]þ (m/
z ¼ 259); 2[PBu4n]þClꢀ (m/z ¼ 553); 3[PBun4]þ2Clꢀ (m/
z ¼ 847); 4[PBun4]þ[PbCl4Ph2]2ꢀClꢀ (m/z ¼ 1576).
Anion and cation of [PPh4]þ[PbCl2Ph3]ꢀ (21) were
observed separately. The [PPh4]þ ion was detected in
‘‘positive ionisation mode’’: m/z ¼ 339.1323 (C24H20P;
deviation: 7.7 ppm). The [PbCl2Ph3]ꢀ ion was detected
in ‘‘negative ionisation mode’’: m/z ¼ 509.0340
(C18H15Cl2Pb; deviation: 4.5 ppm).
Compound 21 consists of isolated cations and anions,
ꢀ
with a closest Pb ꢂ ꢂ ꢂ Cl distance of 7.698 A between two
anions. The anions do not form chains. Their geometry
is trigonal bipyramidal with the chlorine atoms occu-
pying the axial positions. An ORTEP view of 21 is
shown in Fig. 3, selected bond distances and angles are
listed in Table 9.
The Pb–Cl distances in 20 and 21 are essentially
identical, while the Pb–C distances in 20 are about 1%
longer than those in 21.
4. Summary
The extension of a synthetic approach leading to
novel complexes incorporating distorted trigonal bipy-
ramidal [SnR02Cl3]ꢀ anions with both aryl groups in the
equatorial position to include phenylchloroplumbates
6
These by-products were not analysed further.
The exact values depend on solvent and concentration. For PbPh4
7
shift values of d ¼ ꢀ166 to )183 ppm have been reported. See [16].

D. Weber et al. / Inorganica Chimica Acta 357 (2004) 125–134
133
Fig. 4. Mass spectrum of 3[PBu4n]þ[PbCl4Ph2]2ꢀ. Insert: Calculated distribution.
unexpectedly yielded two complexes, [PBun4]2[PbPh2Cl4]
(20) and [PPh4][PbPh3Cl2] (21) with different geometry.
In case of the reaction between [PBun4]þClꢀ and
PbCl2Ph2, a two chloride transfer was the favoured re-
action, leading to the distorted octahedral [PbPh2Cl4]2ꢀ
anion. However when [PPh4]þClꢀ was reacted with
PbCl2Ph2 at a higher temperature, a trigonal bipyra-
midal [PbCl2Ph3]ꢀ anion was formed.
Academic Exchange Service (DAAD) for financial
support. SMART 1K CCD data were collected through
the Ohio Crystallographic Consortium, funded by the
OhioBoardofRegents1995InvestmentFund(CAP-075),
located at the University of Toledo, Instrumentation
Center in A & S, Toledo, OH 43606. J.A. Krause-Bauer
thanks Dr. A. Pinkerton (Department of Chemistry,
University of Toledo) for use of his SMART 2K CCD
diffractometer.
5. Supplementary material
References
Cristallographic data for structural analysis of com-
pounds 8, 9, and 16–19 have been deposited with the
Cambridge Crystallographic Data Centre, CCDC (Nos.
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NMR spectroscopic data for complexes 1–19, IR spec-
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ther HR-MS data of complexes 20 and 21 are available
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