The synthesis and characterization of three oxidized derivatives of bis(diphenylphosphino)pyridine and their Sn(IV) complexes

Article abstract of DOI:10.1016/S0277-5387(03)00291-2

The synthesis and spectroscopic characterization of three chalcogenophosphoryl ligands derived from pyridine is reported. The synthesis was based on the oxidation of C₅H₃N(PPh₂)₂ by elemental sulfur and selenium, and hydrogen peroxide. As a part of our study on the coordination chemistry of the ligands, three new Sn(IV) complex cations of the general formula {[Ph₂P(E)-C₅H₃N-P(E)Ph₂] SnCl₃}⁺ (E = O, S, Se) were also synthesized. All compounds were characterized by ³¹P NMR and X-ray crystallography. The organic ligands are tridentate, with both chalcogens and nitrogen involved in chelation. The cations show an approximate octahedral core geometry and are paired with either SnCl₅^- or SnCl₅(OH₂)^- anions.

Full text of DOI:10.1016/S0277-5387(03)00291-2

Polyhedron 22 (2003) 1585ꢃ1593
/
www.elsevier.com/locate/poly
The synthesis and characterization of three oxidized derivatives of
bis(diphenylphosphino)pyridine and their Sn(IV) complexes
Richard Sevcik, Marek Necas, Josef Novosad *
Faculty of Science, Department of Inorganic Chemistry, Masaryk University, Kotlarska 2, CZ-61137 Brno, Czech Republic
Received 6 January 2003; accepted 24 March 2003
Dedicated to Professor Steinar Husebye, Department of Chemistry, University of Bergen (Norway), on the occasion of his 70th birthday
Abstract
The synthesis and spectroscopic characterization of three chalcogenophosphoryl ligands derived from pyridine is reported. The
synthesis was based on the oxidation of C5H3N(PPh2)2 by elemental sulfur and selenium, and hydrogen peroxide. As a part of our
study on the coordination chemistry of the ligands, three new Sn(IV) complex cations of the general formula {[Ph2P(E)-C5H3N-
P(E)Ph2]SnCl3}ꢀ (EꢁO, S, Se) were also synthesized. All compounds were characterized by 31P NMR and X-ray crystallography.
/
The organic ligands are tridentate, with both chalcogens and nitrogen involved in chelation. The cations show an approximate
octahedral core geometry and are paired with either SnCl5ꢂ or SnCl5(OH2)ꢂ anions.
# 2003 Elsevier Science Ltd. All rights reserved.
Keywords: Diphosphino ligands; Chalcogens; Pyridine; Tin(IV); X-ray crystallography
1. Introduction
derivatives might be expected to be less flexible due to
their central rigid part and the neighboring sterically
demanding phenyl groups. Here we report the prepara-
tion of oxidized derivatives of bppp and their Sn(IV)
complexes and investigations into the crystal and
molecular structures.
Research in the area of organophosphorus derivatives
of pyridine has focused mainly on bis(diphenylpho-
sphino)pyridine (bppp) [1]. Bis(diphenylphosphino)pyr-
idine is relatively easily oxidized on both its terminal
phosphorus atoms and bis(diphenylphosphoryl)pyridine
was first described in 1978 [2], and the thio and seleno
analogues are known since 1990 [3]. Nevertheless, a
search of the Cambridge structural database [4] reveals
only few examples of coordination compounds of bppp
but no examples of complexes derived from [Ph2P(E)-
2. Experimental
All reactions were performed under argon in anhy-
drous conditions using conventional Schlenk techniques
with the exception of hydrogen peroxide oxidation. All
chemicals were used as supplied and solvents were dried
by standard methods and were distilled prior to use [6].
31P NMR spectra were recorded in CH2Cl2 using a
Bruker AVANCE DRX 300 instrument and were
referenced to H3PO4 (85%). IR spectra were recorded
on Nujol mulls using a Bruker IFS 28 spectrometer.
Microanalyses were performed using a Fisons EA 1108
instrument at the Palacky University, Olomouc, Czech
Republic.
C5H3N-P(E)Ph2] (EꢁO, S, Se) or the ligand itself.
/
Surprisingly, there is no occurrence of bppp. Oxidized
bppp derivatives can be considered as the pyridine
analogues of tetraphenylimidodiphosphinates Ph2P(E)-
NH-P(E)Ph2 (EꢁO, S, Se) which were found to be
/
excellent ligands after deprotonation through the co-
ordination via the lone pairs of the chalcogen to the
metal [5]. Comparing to imidodiphosphinates the bppp
* Corresponding author. Tel.:
41211214.
E-mail address: novosad@chemi.muni.cz (J. Novosad).
ꢀ
/
420-5-41129325; fax:
ꢀ/420-5-
0277-5387/03/$ - see front matter # 2003 Elsevier Science Ltd. All rights reserved.
doi:10.1016/S0277-5387(03)00291-2

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R. Sevcik et al. / Polyhedron 22 (2003) 1585ꢃ1593
/
3. Ligands synthesis
Calc. for C29H23NP2S2: C, 68.0; H, 4.5; N, 2.7; S, 12.5%.
m.p.: 204ꢃ205 8C. IR: 3076 vw, 3059 w, 3049 vw, 1560
/
3.1. (Ph2P)2C5NH3 (bppp, 1)
m, 1437 vs, 1108 s, 1102 s, 987 m, 808 s, 799 m, 743 s, 720
vs, 694 vs, 647 vs, 521 vs, 510 s, 492 s, 481 m, 469 w, 451
w, 412 vw. 31P{1H} NMR: d 38.9 singlet (see Fig. 3).
A solution of triphenylphosphine (46.3 g, 0.177 mol)
in anhydrous tetrahydrofuran (thf) (75 ml) was added
over 1.5 h into a solution of sodium metal (8.2 g, 0.357
mol) in liquid ammonia (400 ml) while stirring and the
reaction was continued for 1 h. Then, ammonium
chloride (9.5 g, 0.177 mol) was added in small portions.
After 1.5 h, a solution of 2,6-difluoropyridine (7.8 ml, 86
mmol) was added dropwise over 1 h and stirring was
maintained for the next 1 h. Finally, toluene (150 ml)
was added and the reaction mixture was left standing
overnight at room temperature to evaporate excess
ammonia. The mixture was then refluxed until no
ammonia vapors were detected. After all solvents were
removed by distillation and replaced by dichloro-
methane (350 ml), the insoluble solid was filtered-off.
Then, the volume of dichloromethane was reduced by
half and methanol was added (120 ml). The procedure
was completed by gradual elimination of the remaining
dichloromethane leading to precipitation of bppp, which
was collected by filtration and dried in vacuo. Yield:
25.1 g (65%). Anal. Found: C, 78.3; H, 5.2; N, 3.5. Calc.
3.4. [Ph2P(Se)]2C5NH3 (bpppSe2, 4)
1 (4.87 g, 11 mmol) was dissolved in toluene (140 ml)
and grey selenium powder (1.75 g, 22 mmol) was added.
After 18 h of refluxing, excess selenium was removed by
filtration, the mixture was cooled to room temperature
and colorless crystals were filtered-off, washed with
methanol and dried. The filtrate, concentrated to
approximately 35 ml, was stored at ꢂ20 8C overnight
/
to yield the second fraction of product. The white solid
was filtered-off, washed with methanol and dried. Yield
(sum): 5.41 g (81%). Anal. Found: C, 58.1; H, 3.8; N,
2.3. Calc. for C29H23NP2Se2: C, 57.6; H, 3.8; N, 2.3%.
m.p.: 241ꢃ242 8C. IR: 3073 vw, 3053 w, 3048 vw, 1556
/
m, 1480 m, 1436 vs, 1425 m, 1372 m, 1309 w, 1157 w,
1100 s, 986 m, 804 m, 795 m, 742 s, 703 s, 692 vs, 618 w,
574 vs, 563 s, 515 s, 505 s, 482 s, 445 m, 410 w. 31P{1H}
1
NMR: d 33.1 singlet, J[PÃ
/Se] 748.5 Hz (see Fig. 4).
for C29H23NP2: C, 77.8; H, 5.2; N, 3.2%. m.p.: 124ꢃ
/
125 8C. IR: 3071 w, 3056 w, 3025 w, 1546 s, 1478 m,
1434 s, 1421 s, 1094 m, 748 vs, 694 vs, 504 m, 496 m, 485
4. Complexes synthesis
m, 465 m. 31P{1H} NMR: d ꢂ
/2.8 singlet (see Fig. 1).
4.1. [SnCl3{[Ph2P(O)]2C5NH3}][SnCl5(H2O)] (5)
3.2. [Ph2P(O)]2C5NH3 (bpppO2, 2)
A solution of tin tetrachloride (0.2 ml, 1.56 mmol) in
CH2Cl2 (5 ml) was dropped into a solution of 2 (0.40 g,
0.78 mmol) in CH2Cl2 (10 ml) over 10 min. The reaction
mixture was left stirring over 12 h and a white solid was
filtered-off. The filtrate was concentrated to approxi-
mately 7 ml. A white solid was then collected by
filtration, washed with diethylether and dried. Yield:
0.74 g (85%). Anal. Found: C, 32.8; H, 2.5; N, 1.3. Calc.
A solution of 1 (5.0 g, 11 mmol) in anhydrous thf (50
ml) was cooled to 10 8C and hydrogen peroxide (30%, 6
ml, 58 mmol) was added dropwise over 30 min and then
the reaction mixture was left stirring at room temperature
for 1.5 h. A white suspension was concentrated in vacuo
and diethylether (100 ml) was added to give a white solid.
Yield: 5.2 g (97%). Anal. Found: C, 69.4; H, 4.9; N, 3.1.
for C29H25Cl8NO3P2Sn2×
/
CH2Cl2: C, 32.7; H, 2.5; N,
Calc. for C29H23NP2O2×
/
H2O2: C, 67.8; H, 4.9; N, 2.7%.
1.3%. m.p.: 193ꢃ198 8C (decomposition). IR: 3057 w,
/
m.p.: 229ꢃ230 8C. IR: 3518 m, 3429 m, 3294 w, 3198 w,
/
1589 m, 1460 m, 1437 s, 1375 m, 1268 w, 1166 w, 1120
vs, 1048 s, 1021 s, 995 m, 812 m, 742 s, 729 m, 700 m,
3074 w, 3057 w, 1666 m, 1437 s, 1188 s, 1164 m, 1123 m,
876 vw, 722 m, 706 m, 695 m, 556 s, 539 m, 526 vs, 502 w.
31P{1H} NMR: d 21.3 singlet (see Fig. 2).
686 s, 614 w, 577 m, 556 vs, 517 vs, 431 w. 31P{1H}
2
NMR: d 36.2 singlet, J[PÃ
/Sn] 112.8 Hz.
3.3. [Ph2P(S)]2C5NH3 (bpppS2, 3)
4.2. [SnCl3{[Ph2P(S)]2C5NH3}][SnCl5] (6)
1 (5.0 g, 11 mmol) was dissolved in toluene (125 ml)
and sulfur (0.72 g, 22 mmol) was added. After 8 h of
refluxing, the mixture was cooled to room temperature
and a white solid was filtered-off and washed with
methanol. The filtrate was concentrated in vacuo to
A solution of tin tetrachloride (0.17 ml, 1.47 mmol) in
CH2Cl2 (8 ml) was added over 10 min into a solution of
3 (0.38 g, 0.73 mmol) in CH2Cl2 (12 ml). After being
stirred for 12 h, the solution was concentrated in vacuo
to approximately 4 ml and diethylether (12 ml) was
added. A white solid was collected by filtration, washed
with diethylether and dried. Yield: 0.75 g (91%). Anal.
Found: C, 32.3; H, 2.3; N, 1.2. Calc. for
approximately 35 ml and stored at ꢂ20 8C overnight;
/
another fraction of product was collected by filtration,
washed with methanol and dried. Yield (sum): 4.98 g
(89%). Anal. Found: C, 66.5; H, 3.5; N, 2.6; S, 11.0.
C29H23Cl8NP2S2Sn2×
/
CH2Cl2: C, 32.2; H, 2.2; N, 1.3%.

R. Sevcik et al. / Polyhedron 22 (2003) 1585ꢃ
/
1593
1587
m.p.: 143ꢃ
/
147 8C (decomposition). IR: 3056 w, 1610 w,
Details of the data collection, cell determination and
structure refinement are listed in Table 1.
1583 w, 1562 w, 1458 m, 1440 s, 1377 m, 1335 w, 1312 w,
1256 w, 1194 w, 1104 s, 1096 s, 1010 m, 996 m, 792 m,
746 m, 738 m, 721 m, 710 m, 685 s, 622 s, 606 s, 580 w,
514 vs, 491 s. 31P{1H} NMR: d 47.0 singlet, J[PÃ
86.9 Hz.
2
/Sn]
6. Results and discussion
The synthesis of bppp was based on the reported
method [3]; however, a new way of product isolation
was designed leading to an increased reaction yield of
65% (lit. approximately 40%). After the reaction was
complete, the solvent was replaced by dichloromethane
and the insoluble sodium fluoride was filtered-off. The
product was then precipitated from dichloromethane
solution in the pure form by addition of methanol. In
the method reported previously, after evaporation of
toluene, the oily residue was repeatedly triturated with
methanol to obtain the crude product. The oxidized
derivatives of bppp were prepared by direct oxidation
using either hydrogen peroxide or elementary sulfur or
selenium (Eq. (1)). We suggested toluene as a solvent for
synthesis of dithio and diseleno derivatives to shorten
reaction times; moreover, this alteration led to a
simplified isolation of pure products in high yields. In
contrast to the method described previously, the pro-
ducts are now obtained as crystalline solids directly from
the reaction mixtures. 31P NMR spectra of ligands show
4.3. [SnCl3{[Ph2P(Se)]2C5NH3}][SnCl5] (7)
A solution of tin tetrachloride (0.15 ml, 1.24 mmol) in
CH2Cl2 (10 ml) was added over 10 min into a solution of
4 (0.38 g, 0.62 mmol) in CH2Cl2 (15 ml); the reaction
mixture turned to yellow. After being stirred for 12 h,
the solution was concentrated in vacuo to approxi-
mately 7 ml and diethylether (10 ml) was added. A pale
yellow solid was filtered-off, washed with diethylether
and dried. Yield: 0.67 g (90%). Anal. Found: C, 29.9; H,
2.1; N, 1.2. Calc. for C29H23Cl8NP2Se2Sn2×
/
1.5CH2Cl2:
C, 29.2; H, 2.1; N, 1.1%. m.p.: 140ꢃ145 8C (decomposi-
/
tion). IR: 3050 w, 1585 w, 1558 w, 1437 vs, 1335 w, 1312
w, 1192 w, 1098 s, 1071 w, 996 m, 794 w, 743 s, 703 s,
687 s, 617 w, 573 m, 552 s, 516 m, 504 s, 483 m, 445 w.
31P{1H} NMR: d 44.3 singlet, 1J[PÃ
/
Se] 580.8 Hz, 2J[PÃ
/
1
Sn] 114.7 Hz, J[PÃ
/C] 81.4 Hz.
5. Crystallography
singlets with splitting due to 31PÃ
case of 4. Characteristic bands observed in the FTIR for
PÄE bonds correspond to literature values [2,3].
/
77Se coupling in the
Diffraction data were collected on a KUMA KM-4 k-
/
(1)
axis diffractometer with graphite-monochromated Mo
˚
0.71073 A) equipped with a CCD
All manipulations during the tin complexes syntheses
(Eq. (2)) were made in strictly anhydrous conditions due
to extreme hygroscopicity of tin tetrachloride. All
complexes prepared are unstable in solution when
exposed to moisture/oxygen or higher temperatures
and decompose back to the starting ligands as indicated
by the 31P NMR spectra. As expected, the stability of
the tin complexes decreases from 5 to 7 in accordance
with increasing ‘‘softness’’ of the donor chalcogen atoms
in the ligands. Melting points of Sn(IV) complexes are
not sharp and the compounds decompose when melting.
Ka radiation (lꢁ
/
detector. The intensity data were corrected for Lorentz
and polarization effects. All the structures were solved
by direct methods and refined by full-matrix least-
squares methods using anisotropic thermal parameters
for the non-hydrogen atoms. The software packages
used were Xcalibur CCD system [7] for the data
collection/reduction, and ShelXTL [8] for the structure
solution, refinement and drawing preparation (thermal
ellipsoids are drawn at the 50% probability level).

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R. Sevcik et al. / Polyhedron 22 (2003) 1585ꢃ
/
1593
Table 1
Crystal data and refinement parameters
1
2
3
4
5
6
7
Empirical formula
C
29H23NP2
C29H25NO4P2
C29H23NP2S2
C29H23NP2S2
C30H23Cl10
-
C30H25Cl10
NP2S2Sn2
1117.45
-
C30.5H23Cl11
NP2Se2Sn2
1250.69
-
NO3P2Sn2
1099.31
120(2)
Formula weight
Temperature (K)
Crystal system
Space group
447.42
120(2)
513.44
120(2)
triclinic
511.54
120(2)
605.34
120(2)
120(2)
monoclinic
P21/n
120(2)
orthorhombic
Pbca
monoclinic
C2/c
monoclinic
P21/c
monoclinic
P21/c
monoclinic
C2/c
¯
P1
/
˚
a (A)
15.062(3)
13.231(3)
13.026(5)
10.523(2)
10.925(2)
13.107(3)
99.88(3)
104.67(3)
116.24(3)
1235.7(4)
2
13.209(3)
16.344(3)
12.356(2)
13.279(3)
16.582(3)
12.355(2)
35.167(7)
10.515(2)
21.819(4)
10.767(2)
31.586(6)
12.569(3)
13.085(3)
18.929(4)
34.366(7)
˚
b (A)
˚
c (A)
a (8)
b (8)
g (8)
Volume (A )
Z
Calculated density
(Mg mꢂ3
m (mmꢂ1
116.91(3)
112.31(3)
112.11(3)
98.18(3)
112.89(3)
3
˚
2314.8(8)
4
1.284
2467.8(8)
4
1.382
2520.4(8)
4
1.595
7986(3)
8
1.829
3966.1(14)
4
1.871
8512(3)
8
1.952
1.380
)
)
0.205
0.213
0.365
3.080
2.033
2.145
3.675
Crystal size (mm)
0.40ꢄ
0.20
3.49ꢃ
/
0.40ꢄ
/
0.60ꢄ
0.40
/
0.40ꢄ
/
0.60ꢄ
0.25
/
0.25ꢄ
/
0.40ꢄ
0.20
/
0.30ꢄ
/
0.50ꢄ
0.40
/
0.50ꢄ
/
0.50ꢄ
0.40
/
0.40ꢄ
/
0.40ꢄ
0.30
/
0.40ꢄ
/
u range (8)
Number of reflections 6978
Independent data 2025
/
24.99
3.33ꢃ
7767
4213
/25.00
3.31ꢃ
13780
4334
/
25.00
3.56ꢃ
10137
4156
/
25.00
3.37ꢃ
23864
7014
/
25.00
3.24ꢃ
14283
6005
/
24.46
3.20ꢃ
41888
7487
/
25.00
Final R indices [I ꢀ
/
0.0314, 0.0785 0.0329, 0.0833
0.0296, 0.0759
0.0299, 0.0863
0.0498, 0.1099 0.0329, 0.0805 0.0807, 0.1832
2s(I)]
ꢂ3
˚
Drmax/Drmin (e A
)
0.230 and
0.289
0.358 and
0.339
0.344 and
0.489 and
2.064 and
1.426
1.262 and
1.008
3.232 and
1.852
ꢂ
/
ꢂ
/
ꢂ0.351
/
ꢂ0.394
/
ꢂ
/
ꢂ
/
ꢂ
/
31P{1H} NMR spectra of the tin complexes show
splitting due to 31PÃ
Sn coupling in all cases together
with 31PÃ77Se coupling in the case of 7. Moreover, in
carbon cou-
Table 1. Unlike in the corresponding imidodiphosphi-
nates, there are no hydrogens suitable for hydrogen
bonding present in the ligand molecules. While many
imidodiphosphinates and related compounds form hy-
drogen-bonded polymers or dimers in the solid state [9],
there are no especially short intermolecular contacts in
/
/
31P{1H} NMR spectra of 7, phosphorusÃ
/
pling was observed, which was proven by an additional
13C NMR experiment.
(2)
Crystals suitable for X-ray structure determination
were usually obtained by cooling the reaction mixtures
and the crystals of 1 were obtained by the slow diffusion
1, 3 and 4. In the crystal packing of 2, the intermolecular
connection is allowed through the molecules of hydro-
gen peroxide, which leads to a chain arrangement (Fig.
1).
The ligand molecules adopt twofold internal symme-
try in general, with the symmetry axis connecting
of methanol into a dichloromethane solution of
1. Compound 2 crystallized as the peroxohydrate.
Crystal data and refinement parameters are shown in

R. Sevcik et al. / Polyhedron 22 (2003) 1585ꢃ
/
1593
1589
Fig. 1. An ORTEP representation of 1 showing the atom labelling scheme; atom contours are drawn at 50% probability level.
˚
0.161(2) and 0.171(2) A). While in 1 the Ph2P
in 2 (ꢂ
/
groups have arbitrary orientation with respect to the
pyridine center thus suggesting that they are easily
rotated around the PÃ
sterically more demanding Ph2P(E) groups seems to be
more organized. In all three cases, the PÄE bonds tend
/C bonds, the position of the
/
to align with the pyridine plane (see above) and always
point up towards the rest of the pyridine frame such that
the phenyl substituents are located below nitrogen (Figs.
3 and 4). Both chalcogens are therefore far away from
each other as well as from the lone electron pair of the
nitrogen, and phenyl groups do not interfere with
pyridine, all pendants thus taking spatially more favor-
able positions. It must be noted, however, that the
chalcogens must take opposite orientation when acting
in chelation as clearly seen from the present Sn(IV)
complexes. This is also supported by involving the
nitrogen electron pair in coordination, which is prob-
ably the most important barrier of the analogous
arrangement of chalcogens in both complex and free
ligands.
Selected bond lengths and angles are listed in Table 2.
In P(V) ligands, the PÃ
/
C bonds pointing to phenyl rings
are shortened by oxidation of 1 and they become even
shorter in Sn(IV) complexes. Either identical or opposite
trends in P1Ã
Ph2P(E) groups to pyridine are not observed. The
phosphorusÃchalcogen bonds are prolongated upon
/
C1A and P2Ã
/
C5A bonds connecting
Fig. 2. The crystal packing of 2 showing the intermolecular contacts of
[Ph2P(O)-C5H3N-P(O)Ph2] with molecules of hydrogen peroxide.
/
coordination in complexes 5, 6 and 7. The ligands
nitrogen and the opposite carbon vertex in pyridine. The
central pyridine part including both phosphorus atoms
is nearly planar in all ligands, with the biggest mean
deviation from calculated least-squares planes being
˚
0.0476 A in 1. The terminal chalcogen atoms in oxidized
derivatives are more or less deviated from these
derived from bppp have two Ph2P(E) groups connected
through PÃ
/
C and CÃ/N bonds via a disubstituted
pyridine. There is no through-conjugation involving
the central electron-donating groups like in deproto-
nated [EÃ
diphosphinates [5,9]. Thus, as in the corresponding
imidodiphosphinates, the phosphorusÃchalcogen bond
distances are lengthened upon complex formation, while
/
PÃ
/
NÃ
/
PÃ
/
E]ꢂ chains (Eꢁ
/O, S, Se) of imido-
planes*
/
the most deviating are seleniums in
˚
3
/
(ꢂ0.749(2) and 0.736(2) A) and the least are oxygens
/

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R. Sevcik et al. / Polyhedron 22 (2003) 1585ꢃ
/
1593
Table 2
˚
Selected bond lengths (A) and angles (8) for ligands 1ꢃ
/
4 and Sn(IV) compounds 5ꢃ7
/
a
1
2
3
4
5
6
7
Bond lengths
P1Ã
P2Ã
P1Ã
P2Ã
/
E1
1.483(1)
1.475(1)
1.810(2)
1.804(2)
1.339(2)
1.338(2)
1.789(2)
1.791(2)
1.783(2)
1.788(2)
1.941(6)
1.943(6)
1.826(2)
1.823(2)
1.332(2)
1.334(2)
1.805(2)
1.806(2)
1.806(2)
1.810(2)
2.097(1)
2.097(1)
1.829(2)
1.829(2)
1.333(3)
1.336(3)
1.803(2)
1.811(2)
1.811(2)
1.810(2)
1.525(3)
1.989(2)
1.992(2)
1.822(4)
1.819(4)
1.335(5)
1.336(5)
1.774(4)
1.778(4)
1.792(4)
1.773(4)
2.503(1)
2.514(1)
2.287(3)
2.339(1)
2.372(1)
2.387(1)
2.136(3)
2.144(3)
1.832(11)
1.824(10)
1.337(13)
1.345(13)
1.790(11)
1.786(11)
1.789(11)
1.775(10)
2.630(1)
2.599(1)
2.305(8)
2.351(3)
2.392(3)
2.392(3)
/E2
1.514(3)
1.816(5)
1.827(4)
1.344(6)
1.343(6)
1.775(5)
1.763(5)
1.776(5)
1.769(5)
2.085(3)
2.091(3)
2.235(4)
2.308(1)
2.369(1)
2.362(1)
/C1A
1.832(1)
1.348(1)
/C5A
C1AÃ
/N1A
C5AÃ
/N1A
P1Ã
P1Ã
P2Ã
P2Ã
Sn1Ã
Sn1Ã
Sn1Ã
Sn1Ã
Sn1Ã
Sn1Ã
/
C1B
C1C
C1D
C1E
1.821(1)
1.822(1)
1.821(1)
1.822(1)
/
/
/
/E1
/E2
/
N1A
Cl1
Cl2
Cl3
/
/
/
Bond angles
E1Ã
E2Ã
P1Ã
P2Ã
N1AÃ
Cl2ÃSn1Ã
E1ÃSn1Ã
E1ÃSn1Ã
E2ÃSn1Ã
/
P1Ã
/
C1A
110.49(8)
111.24(8)
116.1(1)
115.3(1)
112.62(5)
113.05(6)
114.3(1)
113.1(1)
112.24(8)
113.15(8)
114.4(2)
113.1(2)
104.6(2)
105.4(2)
125.1(3)
112.7(3)
177.29(9)
169.85(4)
157.8(1)
78.8(1)
111.8(1)
111.1(1)
119.2(3)
119.9(3)
177.61(9)
167.51(4)
174.10(4)
87.72(8)
86.95(8)
111.4(3)
111.3(3)
120.1(8)
122.4(7)
179.3(2)
167.6(1)
176.75(4)
88.0(2)
/
P2Ã
/
C5A
/
C1AÃ
/N1A
114.6(1)
/
C5AÃ
/
N1A
Cl1
/
Sn1Ã
/
/
/Cl3
/
/
E2
/
/
N1A
N1A
/
/
79.1(1)
88.8(2)
a
Only half of a molecule forms an asymmetric unit.
Fig. 3. An ORTEP representation of 3 showing the atom labelling scheme; atom contours are drawn at 50% probability level and hydrogen atoms are
omitted for clarity.

R. Sevcik et al. / Polyhedron 22 (2003) 1585ꢃ
/
1593
1591
Fig. 4. An ORTEP representation of 4 showing the atom labelling scheme; atom contours are drawn at 50% probability level and hydrogen atoms are
omitted for clarity.
the other changes throughout the chelate rings are
unimportant on the other hand (in imidodiphosphinate
ligands, the delocalization occurring in the chelate rings
compressed without inducing some repulsion between
nuclei and (b) the small radii of oxygens, which do not
allow the ligand to get closer to the tin without SnÃ
bond compression and/or excessive lengthening of PÃ
bond distances. Thus, the conflict is solved mainly by a
decrease in OÃSnÃN bond angles of approximately 108
/N
is also responsible for the shortening of PÃ
/N bonds).
/O
Each of the oxidized ligands was allowed to react with
SnCl4 to give a set of heteroleptic complexes with a
chelating molecule of Ph2P(E)-C5H4N-P(E)Ph2, and
three chlorine atoms around Sn(IV) in the cationic
part and five chlorines (and an aqua ligand in 5) around
another Sn(IV) center in the anionic part. The structures
of the prepared complexs 5, 6 and 7 are shown in Figs.
/
/
compared to 6 and 7. To avoid the different trans
influence, 5 can be most appropriately compared to the
structurally similar compound [(EtO)2P(O)-(t-Bu)C6H3-
P(O)(OEt)2]SnCl3, where a carbon atom takes the
donating role of nitrogen in 5, and the OÃ
/
SnÃ/O angle
5ꢃ/7. The cations show approximate octahedral core
is distorted in a similar manner (161.18) [10]. In another
two compounds with SnO2Cl3C central cores, trichloro-
bis(hexamethylphosphoric triamide)-phenyl-tin and eth-
yl-trichloro-bis(triphenylphosphine oxide)-tin, where tin
geometry, which is most distorted in the oxygen
derivative. Apparently, this is due to two factors: (a)
the presence of the SnÃ/N bond, which cannot be too
Fig. 5. An ORTEP representation of 5; atom contours are drawn at 50% probability level; hydrogen atoms and dichloromethane solvate molecule are
omitted for clarity.

1592
R. Sevcik et al. / Polyhedron 22 (2003) 1585ꢃ1593
/
donor atoms in chelating ligands are responsible for
deviations from an octahedral geometry. It is interesting
to note that the corresponding bond lengths are system-
atically shorter in 5 than in [(EtO)2P(O)-(t-Bu)C6H3-
˚
˚
P(O)(OEt)2]SnCl3 (about 0.13 A for SnÃ
/
O and 0.1 A for
SnÃCl bonds), which can be most probably attributed to
/
the lack of electrons in the valence shell of the central
Sn(IV) in 5 after Clꢂ displacement. While (EtO)2P(O)-
(t-Bu)C6H3-P(O)(OEt)2ꢂ compensates for this electron
deficiency with its negative charge, the bpppO2 ligand is
neutral in the cationic chelate 5, and the neighboring
atoms get closer to the tin due to its enhanced Lewis
acidity.
In spite of remarkable distortion of the coordination
polyhedron in 5, additional SnÃ
/
N bond shortening can
be noticed. In the series of our three Sn(IV) complexes,
˚
N bond in 5 is about 0.07 A shorter in
the SnÃ
/
comparison to the appropriate bond in 7. The spatial
relations in the Sn(IV) cations are also reflected in the
planarity of the chelate rings. In the selenium derivative,
which has the longest PÃ
complexes, its two PÃSe bonds need not be aligned (the
Seà Se ‘‘torsion angle’’ being 27.0(1)8) while still
allowing almost regular octahedral geometry around tin.
In both other complexes, the planes calculated through
the chelate rings show only insignificant mean devia-
/
E distances among the three
/
/
PÁ Á ÁPÃ
/
Fig. 6. An ORTEP representation of 6; atom contours are drawn at 50%
probability level; hydrogen atoms and dichloromethane solvate
molecule are omitted for clarity.
˚
tions of included atoms (0.0391 A in 5 and 0.0715 A in 6
˚
˚
against 0.1538 A in 7).
In all complexes, the chlorine situated trans to the
nitrogen is slightly but significantly shifted towards tin
than the neighboring two chlorines. The differences
between SnÃ
/
Cl1 and the other two SnÃ
/
Cl bonds average
˚
are 0.058, 0.041 and 0.041 A in 5, 6 and 7, respectively.
This can be viewed as a result of a smaller trans
influence of the chelating ligand related to its weaker
donating properties than that of the opposite chlorine.
Along with the SnÃ
atomic radii of the chalcogen donors from 7 to 5, the
SnÃCl bonds also become progressively shorter.
/N bond shortening and reducing the
/
The Sn(IV) anionic counterparts are mutually differ-
ent in their nature and geometry. While in 6 and 7 the
[SnCl5]ꢂ unit forms more or less a regular trigonal
bipyramid, in 5 it adopts a water molecule in the
coordination sphere to take octahedral geometry. The
anions in 5 and 7 are affected by significant disorder
causing irregularities in bond lengths and angles, thus
making the precise structural study difficult. In the
SnCl5(OH2)ꢂ anion, the OÃ
/
SnÃ
/
Cl bond angles (invol-
Fig. 7. An ORTEP representation of 7; atom contours are drawn at 50%
probability level; hydrogen atoms and dichloromethane solvate
molecules are omitted for clarity.
ving chlorines non-opposite to oxygen) are compressed,
varying from 84.2(3)8 to 88.1(2)8. This distortion is
similar to what is found in other crystallographically
characterized SnCl5O cores in either SnCl5(OH2)ꢂ or
SnCl5(thf)ꢂ anions [4].
is surrounded by six monodentate ligands (three Cl, one
Ph or Et, two trans-positioned either (Me2N)3PO or
Ph3PO), the SnÃ
angles: 176.08 and 178.68, respectively) [11,12]. Un-
doubtedly, the restricted sterical relations between
/
O bonds are almost co-linear (OÃ
/
SnÃ
/
O
In conclusion, after a long time intensive study of
simple diphosphinate ligands with simple central brid-
ging groups like Ã
/
NHÃ
/
or Ã
/
(CH2)n Ã/, their more

R. Sevcik et al. / Polyhedron 22 (2003) 1585ꢃ
/
1593
1593
complicated variations with larger bridges like aniline
[13] and ferrocene [14] were presented recently. These
ligands bring more flexibility in their skeletons (ferro-
cene) leading to a variety of coordination modes on the
one hand and the more compact frames (pyridine) with
more restricted coordination geometries on the other.
References
[1] F.A. Cotton, E.V. Dikarev, G.T. Jordan, IV, C.A. Murillo, M.A.
Petrukhina, Inorg. Chem. 37 (1998) 4611.
[2] G.R. Newkome, D.C. Hager, J. Org. Chem. 43 (1978)
947.
[3] H.Ch.E. McFarlane, W. McFarlane, A.S. Muir, Polyhedron 9
(1990) 1757.
[4] F.H. Allen, O. Kennard, 3D search and research using the
Cambridge structural database, Chem. Des. Automation News
8 (1993) 1, 31.
7. Supplementary material
[5] T.Q. Ly, J.D. Woollins, Coord. Chem. Rev. 176 (1998)
451.
Crystallographic data for the structural analysis have
been deposited with the Cambridge Crystallographic
[6] D.D. Perrin, W.L.F. Armarego, Purification of Laboratory
Chemicals, Pergamon Press, Oxford, 1988.
Data Centre, CCDC Nos. 198667ꢃ198673. Copies of
this information may be obtained free of charge from
The Director, CCDC, 12 Union Road, Cambridge, CB2
/
[7] Oxford Diffraction Ltd., Xcalibur CCD System, CrysAlis Soft-
ware System, Version 1.168, Oxford, UK, 2001.
[8] SHELXTL
1997.
, Version 5.10, Bruker AXS, Inc., Madison, WI,
1EZ, UK (fax: ꢀ44-1223-336033; e-mail: deposit@
/
[9] P. Bhattacharyya, J.D. Woollins, Polyhedron 14 (1995)
3367.
ccdc.cam.ac.uk or www: http://www.ccdc.cam.ac.uk).
[10] M. Mehring, C. Low, M. Schurmann, K. Jurkschat, Eur. J. Inorg.
Chem. (1999) 887.
[11] A.V. Yatsenko, S.V. Medvedev, L.A. Aslanov, Zh. Strukt. Khim.
33 (1992) 126.
Acknowledgements
[12] A.I. Tursina, L.A. Aslanov, S.V. Medvedev, A.V. Yatsenko,
Koord. Khim. 11 (1985) 417.
This work was supported by the Grant Agency of the
Czech Republic (grant No. 203/02/0436) and by the
Ministry of Education of the Czech Republic (MSM
143100011).
[13] Q. Zhang, S.M. Aucott, A.M.Z. Slawin, J.D. Woollins, Eur. J.
Inorg. Chem. (2002) 1635.
[14] M. Necas, M. Beran, J.D. Woollins, J. Novosad, Polyhedron 20
(2001) 741.