Multinuclear NMR studies of diphosphine, diphosphine-dioxide and diarsine complexes of tin(IV) halides. Structures of [SnI4{o-C6H4(AsMe2)2}] and [SnI4{o-C6H4(P(O)Ph<su

Article abstract of DOI:10.1016/S0020-1693(99)00075-4

The complexes [SnX₄(L-L)] (X=Cl or Br, L-L=Me₂PCH₂CH₂PMe₂, Ph₂PCH₂CH₂PPh₂, o-C₆H₄(PPh₂)₂, o-C₆H₄

Full text of DOI:10.1016/S0020-1693(99)00075-4

Inorganica Chimica Acta 288 (1999) 142–149
Multinuclear NMR studies of diphosphine, diphosphine–dioxide
and diarsine complexes of tin(IV) halides. Structures of
[SnI4{o-C6H4(AsMe2)2}] and [SnI4{o-C6H4(P(O)Ph2)2}]
Anthony R.J. Genge, William Levason *, Gillian Reid
Department of Chemistry, Uni6ersity of Southampton, Southampton SO17 1BJ, UK
Received 22 October 1998; accepted 1 February 1999
Abstract
The complexes [SnX4(L–L)] (X=Cl or Br, L–L=Me2PCH2CH2PMe2, Ph2PCH2CH2PPh2, o-C6H4(PPh2)2, o-C6H4(AsMe2)2,
Ph2AsCH2CH2AsPh2) have been isolated from reaction of SnX4 with the ligand in anhydrous CH2Cl2. The complexes have been
characterised by analysis, IR and multinuclear NMR (1H, 31P and 119Sn) spectroscopy. Rare examples of complexes with SnI4
have been isolated with all the above ligands except Ph2AsCH2CH2AsPh2 and similarly characterised. The multinuclear NMR
studies reveal reversible ligand dissociation in some of the chloro- and bromo-complexes in solution, the extent varying with the
neutral ligand involved, but all the iodo-complexes are extensively dissociated in solution. Complexes of PMe3 and the
diphosphine–dioxide o-C6H4(Ph2PO)2 are also described. X-ray structures of [SnI4{o-C6H4(AsMe2)2}] and of [SnI4{o-
C6H4(Ph2PO)2}] and its CH2Cl2 solvate are reported. © 1999 Elsevier Science S.A. All rights reserved.
Keywords: Crystal structures; Tin complexes; Diphosphine complexes; Diarsine complexes; Tin-119 NMR
1. Introduction
terised by vibrational and Mo¨ssbauer spectroscopy and
X-ray crystallography [5–10]. Surprisingly few studies
have reported multinuclear NMR data [11–13] and we
have thus undertaken a systematic study of a selected
range of diphosphine and diarsine ligand complexes.
We have recently reported complexes of tin(IV)
halides with a range of dithioether, diselenoether and
ditelluroether ligands [1–4]. Characterisations were
provided principally by X-ray crystallography in the
solid state, and multinuclear NMR spectroscopy (1H,
119Sn{1H}, 77Se{1H}, 125Te{1H}) in solution. In particu-
lar variable temperature 119Sn{1H}, 77Se{1H} and
125Te{1H} NMR spectroscopy revealed that reversible
dissociation of the Group 16 donor ligands increased
dithioetherBdiselenoetherꢀditelluroether, with the
Lewis acid strength of the SnX4 following the usual
order with X, Cl\Br\I. No complexes of SnI4 were
isolated, although in some systems they were detected
at low temperatures in solution. Tin(IV) halide com-
plexes of Group 15 donors have been known for over
50 years [5] and a considerable range of phosphine and
diphosphine complexes have been prepared and charac-
Complexes
of
the
diphosphine
dioxide,
o-
C6H4(P(O)Ph2)2 were also included for comparison.
2. Experimental
IR spectra were measured as Nujol mulls using a
Perkin-Elmer 983 spectrometer over the range 180–
1
4000 cm−1. H NMR spectra were recorded using a
Bruker AC300 or AM360 spectrometer operating at
300 or 360 MHz, respectively and are referenced to
TMS (l=0). 119Sn{1H} NMR spectra were recorded in
10 mm NMR tubes containing 10–15% deuterated
solvent using a Bruker AM360 spectrometer operating
at 134.2 MHz and are referenced to neat external
SnMe4 (119Sn l=0). Cr(acac)3 was also added to the
NMR solution as a relaxation agent prior to recording
* Corresponding author. Tel.: +44-1703-595 000; fax: +44-1703-
593 781.
E-mail address: wxl@southampton.ac.uk (W. Levason)
0020-1693/99/$ - see front matter © 1999 Elsevier Science S.A. All rights reserved.
PII: S0020-1693(99)00075-4

A.R.J. Genge et al. / Inorganica Chimica Acta 288 (1999) 142–149
143
the 119Sn{1H} NMR spectra, to avoid signal diminution
via the NOE resulting from the negative magnetogyric
moment of the tin nucleus. 31P{1H} NMR spectra were
obtained similarly at 145.5 MHz and referenced to
external 85% H3PO4.
o-C6H4(PPh2)2, Ph2As(CH2)2AsPh2 or o-C6H4(AsMe2)2]
were all made by the same general method, examples of
which are described below. Analytical and spectro-
scopic data are given in Table 1.
All preparations were carried out in dry solvents
under dry dinitrogen using standard Schlenk-tube, vac-
uum line and glove-box techniques. Tin(IV) halides
were obtained from BDH and used as received.
2.1.2. [SnCl4(PMe3)2]
A solution of tin(IV) chloride (0.26 g, 1 mmol) in
dichloromethane (20 cm3) was added to a solution of
trimethylphosphine (0.15 g, 2 mmol) in dichloro-
methane (20 cm3). The complex precipitated as a white
powder which was filtered off and dried in vacuo.
2.1. Synthesis
2.1.1. o-C6H4(P(O)Ph2)2
A solution of o-C6H4(PPh2)2 (0.9 g, 2 mmol) in CHCl3
(15 cm3) was treated with a solution of diiodine (1.05 g,
4 mmol) in CHCl3 (5 cm3). The brownish solution was
transferred to a separating funnel and shaken with
aqueous 2 M NaOH (20 cm3). The colourless organic
phase was separated and the CHCl3 removed under
reduced pressure. The oil produced was crystallised form
CHCl3/EtOH to give white crystals. Yield 0.80 g, 83%.
31P{1H} NMR (CH2Cl2)+33.6, IR (Nujol mull)
w(PꢀO)=1200 cm−1. Anal. Found: C, 75.1; H, 5.3.
C30H24O2P2 requires: C, 75.3; H, 5.0%. EI mass spectrum
m/z=477, 401. Calc. P+ =477, [P–Ph]+ =401.
The complexes [SnX4(PMe3)2] and [SnX4(L–L)] [X=
Cl, Br or I; L–L=Me2P(CH2)2PMe, Ph2P(CH2)2PPh2,
2.1.3. [SnCl4(Me2PCH2CH2PMe2)]
A solution of tin(IV) chloride (0.26 g, 1 mmol) in
dichloromethane (20 cm3) was added to a solution of
the ligand (0.15 g, 1 mmol) in dichloromethane (20
cm3). The complex precipitated as a white powder
which was filtered off and dried in vacuo.
2.1.4. [SnI4(Me2PCH2CH2PMe2)]
Addition of the solution of tin(IV) iodide (0.63 g, 1
mmol) in dichloromethane (20 cm3) to the solution of
ligand (0.15 g, 1 mmol) produced a dark red solution.
The solvent was removed in vacuo to leave a dark red
solid.
Table 1
Analytical and spectroscopic data
Complex
Colour
%Ca
%H
w(Sn–X)b (cm−1
)
1H NMRc
[SnCl4(PMe3)2]
[SnBr4(PMe3)2]
[SnI4(PMe3)2]
white
17.1(17.5)
11.9(12.2)
9.1(9.3)
17.4(17.6)
12.0(12.3)
9.3(9.3)
47.1(47.4)
37.5(37.2)
30.3(30.5)
51.1(51.0)
40.3(40.6)
33.3(33.6)
42.2(41.8)
34.0(33.8)
21.8(22.0)
16.9(16.6)
13.4(13.2)
49.0(48.8)
38.9(39.3)
32.8(32.6)
4.3(4.4)
3.2(3.1)
2.5(2.3)
4.1(3.9)
2.6(2.7)
2.1(2.1)
3.8(3.7)
2.7(2.9)
2.5(2.4)
3.5(3.4)
3.0(3.0)
2.4(2.3)
3.4(3.2)
2.7(2.6)
3.0(3.0)
2.4(2.2)
2.0(1.8)
3.2(3.5)
2.7(2.6)
2.3(2.2)
321
220
–
1.83(m)
1.50(m)
1.56(m)
2.18(m), 1.57(m)
2.21(m), 1.60(m)
–
2.2(m), 7.2–7.9(m)
2.2(m), 7.3–8.0(m)
2.25(m), 7.3–7.9(m)
–
–
–
2.15(s), 7.3–7.8(m)
2.2(s), 7.3–7.7(m)
1.89(s), 7.7(m)
1.8(s), 7.6(m) (250 K)
pale yellow
deep yellow
white
yellow
dark red
white
yellow
dark red
white
yellow
dark red
white
yellow
white
yellow
dark red
white
[SnCl4(Me2PCH2CH2PMe2)]
[SnBr4(Me2PCH2CH2PMe2)]
[SnI4(Me2PCH2CH2PMe2)]
[SnCl4(Ph2PCH2CH2PPh2)]
[SnBr4(Ph2PCH2CH2PPh2)]
[SnI4(Ph2PCH2CH2PPh2)]
[SnCl4{o-C6H4(PPh2)2}]
[SnBr4{o-C6H4(PPh2)2}]
[SnI4{o-C6H4(PPh2)2}]
[SnCl4(Ph2AsCH2CH2AsPh2)]
[SnBr4(Ph2AsCH2CH2AsPh2)]
[SnCl4{o-C6H4(AsMe2)2}]
[SnBr4{o-C6H4(AsMe2)2}]
[SnI4{o-C6H4(AsMe2)2}]
[SnCl4{o-C6H4(P(O)Ph2)2}]d
[SnBr4{o-C6H4(P(O)Ph2)2}]e
[SnI4{o-C6H4(P(O)Ph2)2}]f
325, 310, 299, 283
206, 199, 196, 193
–
313, 299, 294
220, 217, 208, 205
–
320, 313, 310, 300
217, 212, 208, 195
–
325, 317, 310, 303
217, 212, 195
323, 315, 304, 300
217, 209, 195
–
1.6(s), 7.5(br, m) (200 K)
318, 325(sh)
214(br)
–
–
–
–
pale yellow
orange–red
a Calculated value in parenthesis.
b Nujol mulls.
c CDCl3 solution 300 K.
d w(P–O) 1152 cm−1
,
31P{1H} NMR (CDCl3/CH2Cl2) 42.4.
31P{1H} NMR (CDCl3/CH2Cl2) 41.6.
31P{1H} NMR (CDCl3/CH2Cl2) 39.8.
e w(P–O) 1152 cm−1
f w(P–O) 1138 cm−1
,
,

144
A.R.J. Genge et al. / Inorganica Chimica Acta 288 (1999) 142–149
Table 2
Crystallographic data
[SnI4{o-C6H4(AsMe2)2}]
[SnI4{o-C6H4(P(O)Ph2)2}] · CH2Cl2
[SnI4{o-C6H4(P(O)Ph2)2}]
Empirical formula
Formula weight
Space group
C10H16As2SnI4
912.39
C31H26Cl2I4O2P2Sn
1189.71
P21/c
10.119(2)
20.098(2)
18.054(2)
90.37(1)
3671.5(9)
4
C30H24I4O2P2Sn
1104.77
C2221
11.736(3)
18.672(4)
31.896(4)
90
6989(2)
8
2.100
P212121
14.174(8)
15.598(6)
9.247(2)
90
2044(1)
4
2.964
˚
a (A)
˚
b (A)
˚
c (A)
i (°)
U (A )
3
˚
Z
Dcalc (g cm−3
)
2.152
43.20
1.000, 0.578
v(Mo Ka) (cm−1
)
104.91
1.000, 0.441
43.82
1.000, 0.678
Absorption correction
(max., min. transmission factors)
Unique observed reflections
Observed reflections with [Io\2|(Io)]
No. of parameters
2074
1746
104
0.037
0.040
6670
5349
379
0.035
0.043
3402
1961
202
0.039
0.039
Ra
Rw
b
a R=ꢀ(ꢁFobsꢁi−ꢁFcalcꢁi)/ꢀꢁFobs i.
ꢁ
b Rw=ꢂ[ꢀwi(ꢁFobsꢁi−ꢁFcalcꢁi)2/ꢀwiꢁFobsꢁi ].
2
2.2. Single crystal X-ray structures
2.2.2. [SnI4{o-C6H4(P(O)Ph2)2}] · CH2Cl2
All non-H atoms were refined anisotropically and H
atoms were located in the difference map and included
but not refined. A CH2Cl2 solvent molecule was also
identified in the asymmetric unit. The weighting scheme
Details of the crystallographic data collection and
refinement parameters are given in Table 2. Crystals of
[SnI4{o-C6H4(AsMe2)2}] and [SnI4{o-C6H4(P(O)Ph2)2}] ·
CH2Cl2 were obtained by slow evaporation of a
solution of the complex in CH2Cl2 and those of
[SnI4{o-C6H4(P(O)Ph2)}] by layering a CH2Cl2 solution
of the complex with hexane. Data collection used a
Rigaku AFC7S four-circle diffractometer operating at
150 K (except [SnI4{o-C6H4(P(O)Ph2)2}] (orthorhom-
bic), 298 K), using graphite-monochromated Mo Ka
w
−1=|2(F) gave satisfactory agreement analyses. Se-
lected bond lengths and angles are given in Table 4.
Table 3
˚
Selected bond lengths (A) and angles (°) for [SnI4{o-C6H4(AsMe2)2}]
˚
Bond lengths (A)
I(1)–Sn(1)
I(3)–Sn(1)
Sn(1)–As(1)
As(1)–C(1)
As(1)–C(3)
As(2)–C(9)
C(3)–C(4)
C(4)–C(5)
C(6)–C(7)
2.859(2)
2.792(2)
2.716(2)
1.90(2)
1.93(2)
1.92(3)
1.38(2)
1.37(3)
1.38(3)
I(2)–Sn(1)
I(4)–Sn(1)
Sn(1)–As(2)
As(1)–C(2)
As(2)–C(8)
As(2)–C(10)
C(3)–C(8)
C(5)–C(6)
C(7)–C(8)
2.818(2)
2.787(2)
2.752(2)
1.87(2)
1.99(2)
1.98(2)
1.36(3)
1.38(3)
1.40(3)
˚
X-radiation (u=0.71073 A). No significant crystal de-
cay or movement was observed. The data were cor-
rected for absorption using psi-scans (except
[SnI4{o-C6H4(AsMe2)2}], see below). Two structures of
[SnI4{o-C6H4(P(O)Ph2)2}] were determined, one of
which contains CH2Cl2 in the lattice. The structures
were solved by heavy atom methods [14] and developed
by iterative cycles of full-matrix least-squares refine-
ment and difference Fourier syntheses [15].
Bond angles (°)
I(1)–Sn(1)–I(2)
I(1)–Sn(1)–I(4)
I(1)–Sn(1)–As(2)
I(2)–Sn(1)–I(4)
I(2)–Sn(1)–As(2)
I(3)–Sn(1)–As(1)
I(4)–Sn(1)–As(1)
As(1)–Sn(1)–As(2)
Sn(1)–As(1)–C(2)
C(1)–As(1)–C(2)
C(2)–As(1)–C(3)
Sn(1)–As(2)–C(9)
C(8)–As(2)–C(9)
C(9)–As(2)–C(10)
169.76(6)
92.62(5)
84.89(7)
92.56(5)
85.93(6)
87.18(6)
172.63(8)
78.43(7)
116.4(7)
106(1)
I(1)–Sn(1)–I(3)
I(1)–Sn(1)–As(1)
I(2)–Sn(1)–I(3)
I(2)–Sn(1)–As(1)
I(3)–Sn(1)–I(4)
I(3)–Sn(1)–As(2)
I(4)–Sn(1)–As(2)
Sn(1)–As(1)–C(1)
Sn(1)–As(1)–C(3)
C(1)–As(1)–C(3)
Sn(1)–As(2)–C(8)
Sn(1)–As(2)–C(10)
C(8)–As(2)–C(10)
94.59(6)
85.97(6)
93.17(6)
87.77(6)
100.15(6)
165.6l(7)
94.24(7)
117.0(7)
108.8(5)
104.8(9)
107.1(6)
116.2(7)
105.0(7)
2.2.1. [SnI4{o-C6H4(AsMe2)2}]
Since there were no identifiable faces and preliminary
psi-scans did not provide a satisfactory absorption cor-
rection DIFABS [16] was applied with the model at
isotropic convergence. The Sn, I and As atoms were
refined anisotropically and H atoms were included in
˚
fixed, calculated positions with d(C–H)=0.96 A. The
weighting scheme w−1=|2(F) gave satisfactory agree-
ment analyses, and the Flack parameter indicated the
correct enantiomorph. Selected bond lengths and angles
are given in Table 3.
102.1(9)
120.1(7)
104.3(9)
102.6(10)

A.R.J. Genge et al. / Inorganica Chimica Acta 288 (1999) 142–149
145
Table 4
Table 5
˚
˚
Selected bond lengths (A) and angles (°) for [SnI4{o-C6H4
Selected bond lengths (A) and angles (°) for [SnI4{o-C6H4-
(P(O)Ph2)2}] · CH2Cl2 (monoclinic form)
(P(O)Ph2)2}] (orthorhombic form)
˚
˚
Bond lengths (A)
Bond lengths (A)
I(1)–Sn(1)
I(3)–Sn(1)
Sn(1)–O(1)
Cl(1)–C(31)
P(1)–O(1)
P(1)–C(7)
P(2)–O(2)
P(2)–C(19)
C(1)–C(2)
C(2)–C(3)
C(3)–C(4)
C(4)–C(3)
C(5)–C(6)
2.7759(7)
2.7839(8)
2.120(5)
1.74(1)
1.509(6)
1.793(8)
1.513(5)
1.809(8)
1.40(1)
1.40(1)
1.38(1)
1.38(1)
1.387(10)
I(2)–Sn(1)
I(4)–Sn(1)
Sn(1)–O(2)
Cl(2)–C(31)
P(1)–C(1)
P(1)–C(13)
P(2)–C(6)
P(2)–C(25)
C(1)–C(6)
2.7976(7)
2.7796(8)
2.138(5)
1.75(1)
1.823(8)
1.788(8)
1.808(3)
1.787(8)
1.425(10)
I(1)–Sn(1)
I(3)–Sn(1)
Sn(1)–O(1)
P(1)–O(1)
P(1)–C(7)
P(2)–O(2)
P(2)–C(19)
2.780(2)
2.788(2)
2.142(10)
1.50(1)
1.83(2)
1.50(1)
1.81(2)
I(2)–Sn(1)
I(4)–Sn(1)
Sn(1)–O(2)
P(1)–C(1)
P(1)–C(13)
P(2)–C(6)
P(2)–C(25)
2.807(2)
2.772(2)
2.12(1)
1.81(2)
1.79(2)
1.85(1)
1.82(2)
Bond angles (°)
I(1)–Sn(1)–I(2)
I(1)–Sn(1)–I(4)
I(1)–Sn(1)–O(2)
I(2)–Sn(1)–I(4)
I(2)–Sn(1)–O(2)
I(3)–Sn(1)–O(1)
I(4)–Sn(1)–O(1)
O(1)–Sn(1)–O(2)
O(1)–P(1)–C(7)
C(1)–P(1)–C(7)
C(7)–P(1)–C(13)
O(2)–P(2)–C(19)
C(6)–P(2)–C(19)
171.41(6)
94.14(5)
87.3(3)
93.12(5)
88.0(3)
91.5(3)
170.7(3)
80.6(4)
106.6(7)
109.8(8)
107.8(8)
107.6(8)
107.7(8)
I(1)–Sn(1)–I(3)
I(1)–Sn(1)–O(1)
I(2)–Sn(1)–I(3)
I(2)–Sn(1)–O(1)
I(3)–Sn(1)–I(4)
I(3)–Sn(1)–O(2)
I(4)–Sn(1)–O(2)
O(1)–P(1)–C(1)
O(1)–P(1)–C(13)
C(1)–P(1)–C(13)
O(2)–P(2)–C(6)
O(2)–P(2)–C(25)
C(6)–P(2)–C(25)
Sn(1)–O(1)–P(1)
93.79(5)
84.1(3)
89.80(5)
88.0(3)
97.67(6)
171.9(3)
90.2(3)
114.8(7)
111.2(7)
106.6(8)
114.1(7)
110.2(7)
107.2(7)
148.2(7)
Bond angles (°)
I(1)–Sn(1)–I(2)
I(1)–Sn(1)–I(4)
I(1)–Sn(1)–O(2)
I(2)–Sn(1)–I(4)
I(2)–Sn(1)–O(2)
I(3)–Sn(1)–O(1)
I(4)–Sn(1)–O(1)
O(1)–Sn(1)–O(2)
O(1)–P(1)–C(7)
C(1)–P(1)–C(7)
C(7)–P(1)–C(13)
O(2)–P(2)–C(19)
C(6)–P(2)–C(19)
172.42(3)
92.90(2)
91.6(1)
92.89(2)
83.6(1)
92.3(1)
168.8(1)
79.6(2)
107.7(3)
105.6(3)
109.1(4)
109.1(3)
108.3(3)
I(1)–Sn(1)–I(3)
I(1)–Sn(1)–O(1)
I(2)–Sn(1)–I(3)
I(2)–Sn(1)–O(1)
I(3)–Sn(1)–I(4)
I(3)–Sn(1)–O(2)
I(4)–Sn(1)–O(2)
O(1)–P(1)–C(1)
O(1)–P(1)–C(13)
C(1)–P(1)–C(13)
O(2)–P(2)–C(6)
O(2)–P(2)–C(25)
C(6)–P(2)–C(25)
Sn(1)–O(1)–P(1)
92.25(2)
87.0(1)
91.67(2)
86.4(1)
98.93(3)
170.8(1)
89.2(1)
115.3(3)
110.3(3)
108.7(3)
113.5(3)
110.6(3)
106.9(3)
147.7(3)
C(19)–P(2)–C(25) 110.0(8)
Sn(1)–O(2)–P(2) 148.5(7)
31P{1H} NMR spectrum reveals two isomers in the
approximate ratio 1:2. The minor isomer has l=8.0
and 1J(31P–119Sn)=2720 Hz, and the major isomer
l=3.6 1J(31P–119Sn)=2190 Hz. Two triplets in the
119Sn{1H} NMR spectrum (Table 1) can be correlated
with the 31P resonances via the coupling constants. On
standing the resonance of the isomer with l=8.0 di-
minishes and a resonance at l=39.5 appears, assigned
to oxidised phosphine. The relative magnitude of the
coupling constants identifies the higher frequency reso-
nance as that of the trans isomer [13]. Cis–trans iso-
merisation appears slow at 300 K on the NMR time
scale. The observation of two isomers in MeNO2 solu-
tion but of only the trans isomer in the CH2Cl2 solution
could be due to solvent dependent isomerisation, but
given that the solid complex dissolves only partially in
CH2Cl2 it could simply reflect insolubility of the cis
isomer in chlorocarbons.
C(19)–P(2)–C(25) 108.3(3)
Sn(1)–O(2)–P(2) 149.1(3)
2.2.3. [SnI4{o-C6H4(P(O)Ph2)2}]
The Sn, I, P and O atoms were refined anisotropically
and H atoms were placed in fixed, calculated positions
−1
˚
with d(C–H)=0.96 A. The weighting scheme w
=
|2(F) gave satisfactory agreement analyses and the Flack
parameter indicated the correct enantiomorph. Selected
bond lengths and angles are given in Table 5.
3. Results and discussion
3.1. Trimethylphosphine complexes
Reaction of SnX4 with 2 equiv. of PMe3 in anhy-
drous CH2Cl2 produced white [SnX4(PMe3)2] (X=Cl
or Br) and yellow [SnI4(PMe3)2]. Vibrational spectro-
scopic studies of the complexes with X=Cl or Br
concluded [17] that the complexes existed as the trans
isomer in the solid state. The complexes are poorly
soluble in chlorocarbon solvents but dissolved more
easily in nitromethane. In CD2Cl2 the [SnCl4(PMe3)2]
The [SnBr4(PMe3)2] and [SnI4(PMe3)2] were also
poorly soluble in CH2Cl2, but are readily soluble in
MeNO2 and the 31P{1H} NMR spectra in this solvent
at 300 K are singlets with no evident 117/119Sn satellites.
Cooling the solutions to 250 K resulted in no change to
the 31P{1H} NMR spectra, and no 119Sn{1H} NMR
spectra were observed. It is likely that the form present
in each is the trans isomer, and the absence of a tin
resonance and of tin satellites reflects reversible ligand
dissociation. Unfortunately the very poor solubility in
chlorocarbons and the limited liquid range of MeNO2
(m.p. −29°C) prevented lower temperature studies.
1
complex exhibited a single resonance in both the H
1
and 31P(1H} (l=6.8, J(31P–119Sn)=2720 Hz) NMR
spectra indicating only a single isomer in solution.
However, in a freshly prepared MeNO2 solution the

146
A.R.J. Genge et al. / Inorganica Chimica Acta 288 (1999) 142–149
The iodo complex decomposes slowly in solution with
oxidation of the phosphine.
31P)/(1J(117Sn–31P)=1.047 (compare k(119Sn)/k(117Sn)=
1.046). The 119Sn{1H} NMR spectrum is a triplet at l
−608. The 31P{1H} and 119Sn(1H} NMR spectra of
[SnBr4{o-C6H4(PPh2)2}] are similar (Table 6), and in
neither case do the spectra vary significantly on cooling
the samples to 190 K. In contrast no 31P{1H} NMR
spectrum was observed from a solution of [SnI4{o-
C6H4(PPh2)2}] in CH2Cl2 at room temperature (r.t.). A
broad feature ca. l −53 appeared on cooling to 230 K,
and this sharpened on further cooling. Even at 190 K
no tin satellites were resolved, but since at this temper-
ature the line-width is still \200 Hz it is possible the
couplings are lost since the 117/119Sn–31P couplings fall
rapidly with the halide Cl\Br, and couplings in the
iodide may be very small. No 119Sn{1H} NMR reso-
nance was observed even at 190 K. Comparison of the
data on the three complexes show that whilst dissocia-
tion is minimal for the chloro- and bromo-complexes
even at 300 K, the iodo-complex is much more labile in
solution. The iodo-complex also undergoes slow con-
version to the diphosphine dioxide complex on standing
in CH2Cl2 solution (see below).
3.2. Diphosphine complexes
The [SnX4(diphosphine)] complexes (Table 1) were
readily obtained by reaction of 1:1 molar ratio of
SnX4 with the diphosphine under oxygen-free condi-
tions in rigorously anhydrous CH2Cl2 solution, the
chlorides and bromides usually precipitating immedi-
ately from the solution, whereas the more soluble (or
more extensively dissociated, see below) iodides were
isolated on evaporation of the solvent. Although the
dry solids appear stable under nitrogen, in solution
traces of water lead to samples containing significant
amounts of phosphine oxide impurities, identified by
both IR and 31P{1H} NMR spectroscopy. The IR
spectra showed several features at ca. 320 (X=Cl) and
ca. 220 (X=Br) cm−1 consistent with the expected
cis-SnX4 groups (theory 4, 2A1+B1+B2). The 1H
NMR spectra (Table 1) were relatively uninformative
and discussion will concentrate on the 31P and 119Sn
NMR data.
Changing from the rigid o-phenylene backbone to
the more flexible –CH2CH2– results in increased ten-
dency of the [SnX4(diphosphine)] complexes to re-
It is useful to discuss the different ligand systems in
turn. The 31P{1H} NMR spectrum of [SnCl4{o-
C6H4(PPh2)2}] in anhydrous CH2Cl2 at 300 K shows a
singlet at l −13.9, with clearly resolved satellites
versibly
dissociate
ligand
in
solution.
The
[SnX4(Me2PCH2CH2PMe2)] (X=Cl or Br) complexes
were very poorly soluble in CH2Cl2 and, although
1
1
1J(117Sn–31P)=690, J(119Sn–31P)=720 Hz, J(119Sn–
Table 6
119Sn{1H} and 31P{1H} NMR data for the diphosphine and diarsine complexes
Complexa
l(31P{1H})b
(ppm)
l(119Sn{1H})c
(ppm)
1J(119Sn–31P)d
(Hz)
Solvent
Temperature
(K)
[SnCl4(PMe3)2]
[SnCl4(PMe3)2]
(trans) 6.8
(cis) 3.6
(trans) 8.0
(trans) −3.0
(trans) −3.7
−18.8
−31.0
n.o.
−20.9
−20.9
−26.0
−28.5
−40 (br)
−13.9
−24.2
−52.5
–
n.o.
2720
2190
2768
n.o.
n.o.
890
CH2Cl2
MeNO2
MeNO2
MeNO2
MeNO2
CH2Cl2
CH2Cl2
CH2Cl2
Me2CO
CH2Cl2
Me2CO
CH2Cl2
CH2Cl2
CH2Cl2
CH2Cl2
CH2Cl2
CH2Cl2
CH2Cl2
CH2Cl2
CH2Cl2
CH2Cl2
300
−630(t)
−646(t)
n.o.
300 (119Sn at 250 K)
300 (119Sn at 250 K)
[SnBr4(PMe3)2]
[SnI4(PMe3)2]
[SnCl4(Ph2PCH2CH2PPh2)]
[SnBr4(Ph2PCH2CH2PPh2)]
[SnI4(Ph2PCH2CH2PPh2)]
[SnCl4(Me2PCH2CH2PMe2)]
300
300
300
250
190
300
300
300
300
190
300
250
190
300
270
190
250
200
n.o.
−626(t)
−1212(t)
n.o.
−617(t)
n.o.
−1213(t)
n.o.
−2425(t)
−607.5(t)
−1218(t)
n.o.
460
1080
1005
680
645
ꢁ200
890
[SnBr4(Me2PCH2CH2PMe2)]
[SnI4(Me2PCH2CH2PMe2)]e
[SnCl4{o-C6H4(PPh2)2}]
[SnBr4{o-C6H4(PPh2)2}]
[SnI4{o-C6H4(PPh2)2}]
[SnCl4{o-C6H4(AsMe2)2}]
[SnBr4{o-C6H4(AsMe2)2}]
[SnI4{o-C6H4(AsMe2)2}]e
[SnCl4(Ph2AsCH2CH2AsPh2)]
[SnBr4(Ph2AsCH2CH2AsPh2)]
305
n.o.
−675
–
–
–
–
−1354
−2290
−662
−1368
a Samples made up in dried solvents and run immediately.
b Relative to external 85% H3PO4.
c Relative to neat external SnMe4.
d
96 Hz.
e Resonances only observed in the presence of excess of the Group 15 ligand.

A.R.J. Genge et al. / Inorganica Chimica Acta 288 (1999) 142–149
147
31P(1H} resonances were recorded after long accumu-
lations at 300 K (Table 6), convincing 119Sn{1H} reso-
nances were not observed. The complexes were more
soluble in anhydrous Me2CO in which they gave simi-
lar 31P{1H} NMR spectra to those obtained from
CH2Cl2 solution (with small solvent shifts), and triplet
119Sn{1H} resonances were observed at 300 K (X=Cl)
the free ligand value of 1.2. The 119Sn{1H} spectrum
of this complex in CH2Cl2 solution at 300 K is a
sharp singlet at l −674, and the resonance shows
only a very small temperature drift on cooling the
solution to 190 K. Hence, dissociation of the ligand is
negligible in this complex in CH2Cl2 solution. A solu-
tion of [SnBr4{o-C6H4(AsMe2)2}] at 300 K shows a
very broad l (Me) resonance at 1.6 and a similarly
or on cooling to 270
K (X=Br). The brown
[SnI4(Me2PCH2CH2PMe2)] appears to be stable in the
solid state, but decomposes rapidly in both CH2Cl2 or
Me2CO solution, the initial brown solution depositing
a pale yellow solid in a few minutes, and a 31P{1H}
NMR spectrum of the supernatent solution shows
only decomposition products with l]40. The decom-
position appears to be suppressed by addition of ex-
cess Me2PCH2CH2PMe2 to the CH2Cl2 solution of the
complex, and from solutions containing ca. 5-fold ex-
cess of ligand a broad singlet at l −40 was observed
in the 31P{1H} NMR spectrum at 190 K (the free
diphosphine has l= −48). On warming this reso-
nance was lost at ca. 230 K but reappeared on cool-
ing the solution. The 119Sn{1H} NMR spectrum of the
solution at 190 K exhibited a poorly defined triplet at
1
broad, featureless aromatic resonance in the H NMR
spectrum; both sharpen on cooling to ca. 270 K. No
119Sn{1H} resonance is observed at r.t., but on cooling
to ca. 270 K a singlet appears at l −1354. This
resonance sharpens on cooling further and drifts
slightly to high frequency. The data are consistent
with some reversible ligand dissociation at ambient
temperatures which slows on cooling. In contrast, a
solution of [SnI4{o-C6H4(AsMe2)2}] in CH2Cl2, despite
being a deep red–brown colour showed broad 1H
NMR resonances over the temperature range 300–200
K, and no 119Sn{1H} spectrum was observed at any
temperature down to 190 K. These data suggest that
the iodo-complex is extensively dissociated even at low
1
l −2420, J(119Sn–31P) ca. 200 Hz.
temperatures.
C6H4(AsMe2)2}] containing a 10-fold excess of the di-
arsine showed
weak, broad 119Sn{1H} NMR
A
CH2Cl2 solution of [SnI4{o-
The [SnCl4(Ph2PCH2CH2PPh2)], which is known to
be a chelate complex from a single crystal X-ray study
[9], exhibits a singlet 31P{1H} resonance from a
a
resonance at l −2290 at 190 K, which is tentatively
assigned to the complex. On gentle warming to ca.
200 K the resonance disappeared, but returned on
re-cooling the solution. Despite the solution insta-
bility, dark brown crystals were obtained by slow
evaporation of a solution of the complex in CH2Cl2,
and an X-ray study confirmed these as [SnI4{o-
C6H4(AsMe2)2}]. Addition of a large excess of o-C6H4-
(AsMe2)2 to a CH2Cl2 solution of [SnCl4{o-C6H4-
(AsMe2)2}] produced no change in the 119Sn{1H}
NMR spectrum over the range 300–190 K. This indi-
cates that in marked contrast to the formation of
dodecahedral [MX4{o-C6H4(AsMe2)2}2]n+ by several
early transition metals (e.g. Ti(IV), Mo(IV), Nb(V)
or Ta(V)) [18], eight-coordinate [SnCl4{o-C6H4-
(AsMe2)2}2] does not form with tin(IV).
Two complexes of the phenyl-substituted diarsine
Ph2AsCH2CH2AsPh2, [SnX4(Ph2AsCH2CH2AsPh2)] (X=
Cl or Br) were isolated, but although a mixture of
SnI4 and the ligand forms a very dark red solution in
CH2Cl2, on concentration of the solution inhomoge-
neous products are obtained and we have been unable
to isolate a pure sample of the tin iodide complex of
this ligand. As might be predicted, the complexes of
this weaker donor diarsine are extensively dissociated
in solution in CH2Cl2 and 119Sn{1H} resonances ap-
pear only on cooling (Table 6), although the observed
chemical shifts are little different from those of the
corresponding [SnX4{o-C6H4(AsMe2)2}].
1
CH2Cl2 solution at 300 K at l −18.8 with J(117Sn–
31P)=850, 1J(119Sn–31P)=890 Hz, 1J(119Sn–31P)/
(1J(117Sn–31P)=1.047. The 119Sn{1H} NMR spectrum
is ill-defined at 300 K, but on cooling to 270 K a
triplet at l −626 is clear. The corresponding yellow
[SnBr4(Ph2PCH2CH2PPh2)] was more difficult to ob-
tain pure, and samples are often contaminated with
substantial amounts of phosphine oxide impurities.
The best route to pure samples appears to be the
synthesis in rigorously anhydrous CH2Cl2, followed
by rapid isolation of the solid. The brown
[SnI4(Ph2PCH2CH2PPh2)] dissolves easily in CH2Cl2,
but no 31P or 119Sn resonances were observed over the
temperature range 300–190 K, except for a very weak
feature at l 48 in the former which increased on
standing, and is attributable to a decomposition
product containing oxidised phosphine. The absence
of any resonance attributable to the complex or the
free diphosphine clearly shows that fast exchange is
occuring over the temperature range studied.
3.3. Diarsine complexes
Complexes [SnX4{o-C6H4(AsMe2)2}] were readily
made from CH2Cl2 solutions of SnX4 and the ligand.
The solids appear to be less air- and moisture-sensitive
than many of the diphosphine complexes. The 1H
NMR spectrum of [SnCl4{o-C6H4(AsMe2)2}] shows a
sharp l (Me) resonance at 1.89 which compares with

148
A.R.J. Genge et al. / Inorganica Chimica Acta 288 (1999) 142–149
dioxide complex was confirmed by comparison of the
IR and 31P NMR spectra with those of the genuine
sample made directly from o-C6H4(P(O)Ph2)2.
3.5. X-ray structures of [SnI4{o-C6H4(AsMe2)2}] and
[SnI4{o-C6H4(P(O)Ph2)2}]
Red–brown crystals of [SnI4{o-C6H4(AsMe2)2}] were
obtained by evaporation of a CH2Cl2 solution of the
complex. The structure (Fig. 1, Table 3) reveals a
distorted octahedral geometry at the tin composed of
the chelating diarsine (As–Sn–As=78.47(7)°) and four
iodines with all the (cis) I–Sn–I angles \90° (range
92.59(6)–100.14(6)°). This is the first example of a tin
arsine complex to be structurally characterised, and few
adducts of SnI4 have been subjected to X-ray studies.
The Sn–I distances in the present complex (Sn–ItransI
=
˚
˚
2.817(2), 2.860(2) A, Sn–ItransAs=2.792(2), 2.787(2) A)
may be compared with those reported in trans-
˚
[SnI4(PPr3)2] [8] (2.863(3), 2.872(3) A), in cis-[SnI4-
(Ph3PO)2] [20] (Sn–ItransI 2.781(-), 2.810(-), Sn–ItransO
2.780(-), 2.816(-) A) and in [SnI4(MeS(O)CH2CH2-
Fig. 1. View of the structure of [SnI4{o-C6H4(AsMe2)2}] with num-
bering scheme adopted. Ellipsoids are drawn at 40% probability.
˚
CH2SMe)2] [1] (Sn–ItransI 2.762(2), 2.802(2), Sn–ItransO
˚
2.788(2), 2.780(2) A).
3.4. Diphosphine dioxide complexes
Two different crystalline forms of [SnI4{o-
C6H4(P(O)Ph2)2}] were obtained. Slow evaporation of a
CH2Cl2 solution of [SnI4{o-C6H4(PPh2)2}] produced a
red crystal of the diphosphine dioxide complex as a 1:1
CH2Cl2 solvate (see above) which had a monoclinic cell
(P21/c) whereas a similar solution layered with n-hex-
The ligand o-C6H4(P(O)Ph2)2 was easily obtained by
iodine oxidation of the diphosphine followed by base
hydrolysis [19]. It is a white, air-stable solid which
exhibits w(PꢀO) as a very strong broad feature 1200
cm−1 and l 31P{1H} at 33.6 (CH2Cl2). Addition of
CH2Cl2 solutions of the ligand to similar solutions of
SnX4 (X=Cl or Br) resulted in immediate precipitation
of [SnX4{o-C6H4(P(O)Ph2)2}] complexes. The red–
brown [SnI4{o-C6H4(P(O)Ph2)2}] was isolated on con-
centrating a CH2Cl2 solution of equimolar amounts of
SnI4 and ligand. Coordination to an SnX4 acceptor
results in a fall of 50–60 cm−1 in w(PꢀO). The iodo-
complex is easily soluble in chlorocarbon solvents and
exhibits l31 at 39.8, a small high frequency shift which
P
was essentially unchanged on cooling the solution to
190 K. No 31P–117/119Sn satellites were observed on the
phosphorus resonance even at low temperature, and
attempts to record the 119Sn spectrum were unsuccess-
ful, probably indicating reversible ligand ring opening
and/or dissociation. The corresponding bromo- and
especially the chloro-complex were very poorly soluble
in CH2Cl2, and although 31P{1H} NMR resonances
were observed at 41.6 and 42.4 respectively at 300 K,
low temperature studies were precluded by precipitation
of the complexes on cooling the solutions. This poor
solubility also prevented 119Sn NMR spectra being
recorded.
Crystals of [SnI4{o-C6H4(P(O)Ph2)2}] were initially
obtained by slow evaporation of a CH2Cl2 solution of
[SnI4{o-C6H4(PPh2)2}], their identity as the diphosphine
Fig. 2. View of the structure of [SnI4{o-C6H4(P(O)Ph2)2}] (mono-
clinic form) with numbering scheme adopted. Ellipsoids are drawn at
40% probability and H atoms are omitted for clarity.

A.R.J. Genge et al. / Inorganica Chimica Acta 288 (1999) 142–149
149
ane produced an unsolvated orthorhombic form
References
(C2221). Comparison of the geometries of the two
forms showed no significant differences in bond
lengths or angles (Tables 4 and 5) and hence we
shall discuss the solvated form which was a higher
quality structure (Fig. 2). The Sn–ItransI distances
[1] S.E. Dann, A.R.J. Genge, W. Levason, G. Reid, J. Chem. Soc.,
Dalton Trans. (1996) 4471.
[2] S.E. Dann, A.R.J. Genge, W. Levason, G. Reid, J. Chem. Soc.,
Dalton Trans. (1997) 2207.
[3] A.R.J. Genge, W. Levason, G. Reid, J. Chem. Soc., Dalton
Trans. (1997) 4549.
[4] A.R.J. Genge, W. Levason, G. Reid, J. Chem. Soc., Dalton
Trans. (1997) 4479.
[5] W. Levason, C.A. McAuliffe, Coord. Chem. Rev. 19 (1976) 173.
[6] P.G. Harrison, B.C. Lane, J.J. Zuckerman, Inorg. Chem. 11
(1972) 1537.
[7] D. Cunningham, M.J. Frazer, J.D. Donaldson, J. Chem. Soc.
(A) (1971) 2049.
[8] (a) N. Bricklebank, S.M. Godfrey, C.A. McAuliffe, R.G.
Pritchard, J. Chem. Soc., Chem. Commun. (1994) 695. (b) N.
Bricklebank, S.M. Godfrey, C.A. McAuliffe, K.C. Molloy, J.
Chem. Soc., Dalton Trans. (1995) 1593.
˚
2.7759(7), 2.2976(7)
2.7796(8) A may be compared with the values above,
and Sn–O=2.120(5), 2.138(5) A are similar to those
in cis-[SnI4(Ph3PO)2] 2.148(-), 2.119(-) A [20]. This
A
and Sn–ItransO 2.7839(8),
˚
˚
˚
appears to be the first published structure containing
this diphosphine dioxide, although a copper com-
plex is known [21]. The ligand chelates forming a
seven-membered ring which appears relatively un-
strained.
[9] F. Kunkel, K. Dehnicke, H. Goesmann, D. Fenske, Z. Natur-
forch., Teil B 50 (1995) 848.
[10] F. Sarikahya, Synth. React. Inorg. Met. Org. Chem. 19 (1989)
641.
4. Supplementary material
[11] R. Colton, D. Dakternieks, C.-A. Harvey, Inorg. Chim. Acta 61
(1982) 1.
[12] V.S. Petrosyan, N.S. Yahina, E.J. Gefel, Silicon Germanium Tin
Lead Compd. 9 (1985) 1387.
[13] W. McFarlane, N.H. Rees, Polyhedron 8 (1989) 2047.
[14] P.T. Admiraal, G. Beurskens, G. Bosman, W.P. Garcia-Granda,
S. Gould, R.O. Smits, J.M.M. Smykalla, PATTY, The DIRDIF
Program System, Beurskens, C. Technical Report of the Crystal-
lography Laboratory, University of Nijmegen, The Netherlands,
1992.
Crystallographic data for the structural analysis has
been deposited with the Cambridge Crystallographic
Data Centre. Copies of this information may be ob-
tained free of charge from The Director, CCDC, 12
Union Road, Cambridge, CB2 1EZ, UK (Fax: +44-
1223-336-033; e-mail: deposit@ccdc.cam.ac.uk or
www: http://www.ccdc.cam.ac.uk). The information
comprises H-atom co-ordinates, anisotropic thermal
parameters and full listings of bond lengths and angles
for the structures on quoting the CCDC Numbers
114366, 114367, 114368.
[15] TeXsan: Crystal Structure Analysis Package, Molecular Struc-
ture Corporation, TX, 1995.
[16] N. Walker, D. Stuart, Acta Crystallogr., Sect. A 39 (1983) 158.
[17] (a) I.R. Beattie, G.A. Ozin, J. Chem. Soc. (A) (1970) 370. (b)
D.K. Frieson, G.A. Ozin, Can. J. Chem. 51 (1973) 2685.
[18] M.G.B. Drew, A.P. Walters, J.D. Wilkins, Acta Crystallogr.,
Sect. B 31 (1975) 324.
[19] F. Canziani, F. Zingales, U. Sartorelli, Gazz. Chim. Ital. 94
(1964) 848.
Acknowledgements
[20] A.I. Tursina, L.A. Aslanov, V.V. Chenyshev, S.V. Medvedev,
A.V. Yatsenko, Koord. Khim. 12 (1986) 420.
[21] M.D. Spicer, Ph.D. Thesis, Southampton University, 1988.
We thank the EPSRC and the University of
Southampton for support.
.