The first rigid O,C,O-pincer ligand and its application for the synthesis of penta- and hexacoordinate organotin(IV) compounds

Article abstract of DOI:10.1021/om970847c

The synthesis of the aryldiphosphonic ester C₆H₂[P(O)(OEt)₂]₂-1,3-t-Bu-5 (2) and of its organotin derivatives C₆H₂[P(O)(OEt)₂] ₂-2,6-t-Bu-4-RR′₂Sn-1 (5, R = R′ = Me; 6, R = R′ = Ph; 7, R = Ph, R′ = Cl; 8, R = Ph, R′ = Br) is reported. Also reported is the preparation of the organosilicon and organotin compounds C₆H₂[P(O)(OEt)₂]₂-2,4-Me ₃Si-1 (3), C₆H₂[P(O)(OEt)₂]₂-2,4-(Me ₃Si)₂-1,5 (4), C₆H₃tP(O)(OEt)₂]₂-2,4-Ph ₂RSn-1 (9, R = Ph; 12, R = Br), and C₆H₃[P(O)(OEt)₂]₂-2,4-(Ph ₂RSn)₂-1,5 (10, R = Ph; 11, R = Br). X-ray investigations reveal weak intramolecular Sn-O interactions for 6 (2.865(3)-3.063(4) ?), 9 (2.803(3) ?), and 10 (2.793(2) ?) but strong Sn-O coordinations for 7 (2.203(5)72.278(6) ?) and 11 (2.379(3)/ 2.412(3) ?), indicating the high donor capacity of the new rigid O,C,O- and O,C-chelating ligands in these compounds. NMR studies confirm that the basic coordination geometry found in the solid state is maintained in solution. ? Dedicated to Prof. Manfred Weidenbruch on the occasion of his 60th birthday.

Full text of DOI:10.1021/om970847c

Organometallics 1998, 17, 1227-1236
1227
Th e F ir st Rigid O,C,O-P in cer Liga n d a n d Its Ap p lica tion
for th e Syn th esis of P en ta - a n d Hexa coor d in a te
Or ga n otin (IV) Com p ou n d s†
Michael Mehring, Markus Schu¨rmann, and Klaus J urkschat*
Lehrstuhl fu¨r Anorganische Chemie II der Universita¨t Dortmund,
D-44221 Dortmund, Germany
Received September 29, 1997
The synthesis of the aryldiphosphonic ester C6H2[P(O)(OEt)2]2-1,3-t-Bu-5 (2) and of its
organotin derivatives C6H2[P(O)(OEt)2]2-2,6-t-Bu-4-RR′2Sn-1 (5, R ) R′ ) Me; 6, R ) R′ )
Ph; 7, R ) Ph, R′ ) Cl; 8, R ) Ph, R′ ) Br) is reported. Also reported is the preparation of
the organosilicon and organotin compounds C6H2[P(O)(OEt)2]2-2,4-Me3Si-1 (3),
C6H2[P(O)(OEt)2]2-2,4-(Me3Si)2-1,5 (4), C6H3[P(O)(OEt)2]2-2,4-Ph2RSn-1 (9, R ) Ph; 12, R )
Br), and C6H3[P(O)(OEt)2]2-2,4-(Ph2RSn)2-1,5 (10, R ) Ph; 11, R ) Br). X-ray investigations
reveal weak intramolecular Sn-O interactions for 6 (2.865(3)-3.063(4) Å), 9 (2.803(3) Å),
and 10 (2.793(2) Å) but strong Sn-O coordinations for 7 (2.203(5)/2.278(6) Å) and 11 (2.379(3)/
2.412(3) Å), indicating the high donor capacity of the new rigid O,C,O- and O,C-chelating
ligands in these compounds. NMR studies confirm that the basic coordination geometry
found in the solid state is maintained in solution.
In tr od u ction
Monoanionic L,C,L-coordinating ligands [C6H3(CH2L)2-
2,6]- (L ) -NR2,7 -PR2,8 SR9) and their metal deriva-
tives of type A (Chart 1) are well-studied, and most of
these compounds show fluxional behavior as a result of
the nonrigidity of the donor ligands.
Organotin compounds with coordination numbers
higher than four are still extensively studied because
of their biological activity,1 their enhanced reactivity,2
and their stereochemical nonrigidity.2,3 These intrigu-
ing properties also prompted studies on the bonding in
such compounds.4 Coordination numbers at tin of five,2
six,2 or even seven5 are usually observed in the presence
of at least one electron-withdrawing substituent and are
achieved both by intra-2 and intermolecular3a,b,4a donor-
acceptor interactions. In the case of so-called built-in
ligands, even tetraorganotin compounds may exhibit
penta- and hexacoordinate structures.6
Weichmann et al.10 reported strong intramolecular
-PdOSn interactions in compounds of type B (Chart
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S0276-7333(97)00847-9 CCC: $15.00 © 1998 American Chemical Society
Publication on Web 02/27/1998

1228 Organometallics, Vol. 17, No. 6, 1998
Mehring et al.
Ch a r t 1
Sch em e 1
Ch a r t 2
stannylated aryldiphosphonic esters C6H2[P(O)(OEt)2]2-
2,4-(Ph2XSn)2-1,5 (X ) Ph, Br) with two pentacoordi-
nated tin centers in one molecule as well as of C6H2[P(O)-
(OEt)2]2-2,4-(Ph2XSn)-1 (X ) Ph, Br) with one tin center.
2). However, as far as we are aware, there is no report
on the synthesis and reactivity of organometallic com-
pounds of the general type C (Chart 2). The combina-
tion of the high donor capacity of the PdO groups and
the rigidity of the ligand frame in this type of compound
should allow the isolation of derivatives in which the
metal M shows high coordination numbers and/or
unusual oxidation states.
Resu lts a n d Discu ssion
Syn th etic Asp ects. Compounds 116 and 2 were
obtained by reaction of 1,3-dibromobenzene and 1,3-
dibromo-5-t-Bu-benzene17 with P(OEt)3 and were iso-
lated in 60-70% yield (eq 1).
A suitable precursor for the synthesis of C-type
compounds (Chart 2) should be meta-disubstituted
benzene derivatives of type D (Chart 2), provided that
metalation can be achieved at C2 of the aromatic ring.
The general concept for directed ortho metalations is
well-established for groups such as NR2, CH2NR2, OR,
SO2NR2, or CH2NR2.11 Examples have been reported
for the use of -P(E)(NMe2)2 (E ) S,12 O13) and -P(O)-
Ph214 groups in directed ortho metalations. In the case
of lithiation of Ph3PO by organolithium reagents,
Schlosser14a et al. have demonstrated that there is a
competition between ortho lithiation and nucleophilic
substitution at phosphorus. Recently, the use of lithium
diisopropylamide, hereafter referred to as LDA, for the
metalation of both the tolyl group of ortho-tolylphos-
phonic diethyl ester15 and the aromatic ring of (2-
diethylcarbamoylphenyl)diphenylphosphane oxide14e un-
der very mild conditions has been described.
Treatment of 1 with LDA in Et2O/hexane at -78 °C
resulted in a deep red solution. After quenching the
reaction mixture with Me3SiCl at -78 °C, the crude
product contained the mono, and disilylated species 3
and 4 along with starting material 1 (Scheme 1).
Purification by column chromatography gave 3 and 4
as yellow oils.
This trapping experiment of lithiated 1 with Me3SiCl
(Scheme 1) demonstrated that lithiation occurs exclu-
sively at C4 and C6 and does not take place at all at
C2, which has two neighboring ortho-phosphonyl groups
that are ortho-directing in this type of metalation
reaction.
In this paper, we report on the synthesis of the first
monoanionic O,C,O-pincer ligand {C6H2[P(O)(OEt)2]2-
2,6-t-Bu-4}- and its application in the synthesis of
penta- and hexacoordinate organotin compounds. We
also report on the synthesis and structures of the
Treatment of a hexane/Et2O solution of 2 with LDA
at -78 °C gave an orange suspension of the monolithi-
ated complex C6H2[P(O)(OEt)2]2-2,4-Li-1 (2a ) (eq 2).
(10) (a) Weichmann, H.; Schmoll, C. Z. Chem. 1984, 10, 390. (b)
Weichmann, H.; Petrick, D.; Schmoll, C. Z. Anorg. Allg. Chem. 1987,
550, 140.
(11) (a) Narasimhan, N. S.; Mali, R. S. Synthesis 1983, 964. (b)
Snieckus, V. Chem. Rev. 1990, 6, 879. (c) Beak, P.; Kerrick, S. T.;
Gallagher, D. J . J . Am. Chem. Soc. 1993, 113, 10628. (d) Kremer, T.;
J unge, M.; Schleyer, P. v. R. Organometallics 1996, 15, 3345. (d)
Belzner, J .; Scha¨r, D.; Dehnert, U.; Noltemeyer, M. Organometallics
1997, 16, 285 and references therein.
(12) (a) Craig, D. C.; Roberts, N. K.; Transwell, J . L. Aust. J . Chem.
1990, 43, 1487. (b) Yoshifuji, M.; Ishizuka, T.; Choi, Y. J .; Inamoto, N.
Tetrahedron Lett. 1984, 37, 4097.
Complex 2a was filtered and isolated as a yellow solid,
which was used without further purification as a
reagent in subsequent reactions (vide infra). These
reactions show that in contrast to 1, lithiation of 2
occurs exclusively at C2. Steric protection achieved by
introduction of a tert-butyl group at C5 prevents depro-
tonation at the C4 and C6 positions.
(13) Dashan, L.; Trippet, S. Tetrahedron Lett. 1983, 24, 2039.
(14) (a) Schaub, B.; J enny, T.; Schlosser, M. Tetrahedron Lett. 1984,
25, 4097. (b) Schmid, R.; Foricher, J .; Cereghetti, M.; Scho¨nholzer, P.
Helv. Chim. Acta 1991, 74, 370. (c) Brown, J . M.; Woodward, S. J . Org.
Chem. 1991, 55, 6803. (d) Alcock, N. W.; Brown, J . M.; Pearson, M.;
Woodward, S. Tetrahedron: Asymmetry 1991, 3, 17. (e) Gray, M.;
Chapell, B. J .; Taylor, N. J .; Snieckus, V. Angew. Chem. 1996, 13/ 14,
1609.
(15) Boumekouez, A.; About-J audet, E.; Collignon, N. J . Organomet.
Chem. 1994, 466, 89.
(16) Tavs, P. Chem. Ber. 1970, 103, 2428.
(17) Takayuki, I.; Iwamura, H. J . Am. Chem. Soc. 1991, 113, 4238.

Penta- and Hexacoordinate Organotin(IV) Compounds
Organometallics, Vol. 17, No. 6, 1998 1229
Sch em e 2
Reaction of 2a with Me3SnCl and Ph3SnCl, respec-
tively, afforded the corresponding tetraorganotin com-
pounds C6H2[P(O)(OEt)2]2-2,6-t-Bu-4-R3Sn-1 (5, R ) Me;
6, R ) Ph) in moderate yields (eq 3). The triphenyltin
F igu r e 1. General view (SHELXTL-PLUS) of a molecule
showing 30% probability displacement ellipsoids and the
atom-numbering Scheme for 6a . The same numbering
scheme applies for 6b, the drawing of which is not shown.
bromine to afford C6H2[P(O)(OEt)2]2-2,4-(Ph2BrSn)2-1,5
(11) and C6H3[P(O)(OEt)2]2-2,4-Ph2BrSn-1 (12) (eq 5).
derivative 6 was converted into the corresponding
diorganotin dihalides C6H2[P(O)(OEt)2]2-2,6-t-Bu-4-PhX2-
Sn-1 (7, X ) Cl; 8, X ) Br) by reaction with HCl or
bromine, respectively (eq 4). The driving force for the
Compounds 5-11 are colorless, sharp melting solids,
whereas 12 is an oil. Compounds 5, 6, 9, and 10 are
soluble in common organic solvents such as toluene,
chloroform, and ether; 7 and 8 show moderate solubility
only in polar solvents such as chloroform, tetrahydro-
furan, and pyridine.
Molecu la r Str u ctu r es of 6, 7, a n d 9-11. The
molecular structures of 6, 7, and 9-11 are shown in
Figures 1-5, respectively, and selected interatomic
parameters are collected in Tables 2 and 3. The
structures are molecular with no significant intermo-
lecular contacts in their respective crystal lattices.
The crystal structure of 6 is comprised of the packing
of eight discrete mononuclear molecules in the unit cell.
The asymmetric unit contains two independent mol-
ecules, 6a and 6b, which are chemically identical in
composition but differ significantly in structure.
The coordination geometry at tin in 6a is almost
tetrahedral, as indicated by an average C-Sn-C angle
of 109.7°. The greatest deviations from the ideal
tetrahedral angle are found for C(21)-Sn(1)-C(1) (104.2-
(2)°), C(21)-Sn(1)-C(11) (100.3(3)°), and C(31)-Sn(1)-
C(1) (125.2(3)°). The Sn(1)-C(1) bond distance of
2.168(6) Å is the longest one found among the Sn-C
bonds in 6a , which is caused by a steric repulsion
effected by the rigid ligand frame. A similar effect was
previously reported for C6H2(CF3)3-2,4,6-Ph3Sn-1.18 Fur-
thermore, the Sn(1)-C(11) and Sn(1)-C(21) bond lengths
selective cleavage of two phenyl groups is the formation
of strong PdOSn coordination bonds accompanied by a
chelate effect. It is well-known that intramolecular
assistance by donor groups such as NR2 facilitates the
cleavage of tin-carbon bonds in mutual trans positions.2
No tin-carbon cleavage occurred when 6 was heated
at reflux in toluene with PhOH for 1 day. However,
treating 6 with pure PhOH at 160 °C afforded 2, Ph4-
Sn, and Ph2Sn(OPh)2. The formation of the two latter
compounds can be explained in terms of a redistribution
reaction of Ph3SnOPh initially generated from 6 and
PhOH. The result is somewhat surprising when com-
pared to the behavior of Ph3Sn(CH2)3NMe2 and Ph2Sn-
[(CH2)3NMe2]2, which quantitatively yield Ph2(PhO)-
Sn(CH2)3NMe22d and (PhO)2Sn[(CH2)3NMe2]2,2e respec-
tively, under the same reaction conditions.
Lithiation of 1 with 2 equiv of LDA and subsequent
treatment of the reaction mixture with Ph3SnCl led to
the formation of the mono- and distannyl compounds
C6H3[P(O)(OEt)2]2-2,4-Ph3Sn-1 (9) and C6H2[P(O)(OEt)2]2-
2,4-(Ph3Sn)2-1,5 (10) (Scheme 2). These reacted with

1230 Organometallics, Vol. 17, No. 6, 1998
Mehring et al.
F igu r e 4. General view (SHELXTL-PLUS) of a molecule
showing 30% probability displacement ellipsoids and the
atom-numbering scheme (symmetry transformations used
to generate equivalent atoms, a ) 1 - x, y, 0.5 - z) for 10.
F igu r e 2. General view (SHELXTL-PLUS) of a molecule
showing 30% probability displacement ellipsoids and the
atom-numbering scheme (symmetry transformations used
to generate equivalent atoms, a ) 1 - x, y, z) for 7.
F igu r e 5. General view (SHELXTL-PLUS) of a molecule
showing 30% probability displacement ellipsoids and the
atom-numbering scheme for 11.
The tetrahedral geometry at tin is even more distorted
in 6b as evidenced by two sets of C-Sn-C angles
(104.8(3)°, 102.8(3)°, 96.3 (2)° and 113.0(2)°, 114.4(3)°,
122.5(2)°). The Sn(2)-C(31*) and Sn(2)-C(11*) bond
distances of 2.160(5) and 2.144(6) Å, respectively, are
longer than those in 6a as a result of their pseudotrans
position to the PdO groups. This spatial arrangement
is accompanied by a shortening of the Sn(1*)-O(2*)
contact to 2.865(3) Å, whereas the Sn(1*)-O(1*) dis-
tance (3.063(4) Å) is only slightly elongated.
The existence of two independent molecules in the
crystal lattice of 6 is also reflected by the observation
of two equally intense 119Sn MAS NMR resonances at
-181.7 and -227.7 ppm.
The crystal structure of 7 involves the packing of two
discrete mononuclear molecules in the unit cell. Se-
lected bond lengths and angles are given in Table 2. In
7, the tin atom has a distorted octahedral configuration.
The distortion from the ideal geometry is illustrated by
the C(1)-Sn(1)-C(11), Cl(1)-Sn(1)-Cl(1a), and O(1)-
Sn(1)-O(2) angles of 174.9(3)°, 172.66(12)°, and 161.1-
(2)°, respectively. It results from the rigid geometry of
F igu r e 3. General view (SHELXTL-PLUS) of a molecule
showing 30% probability displacement ellipsoids and the
atom-numbering scheme for 9.
of 2.139(7) and 2.128(6) Å, respectively, are longer than
the Sn(1)-C(31) bond distance of 2.094(4) Å. This is
attributed to two intramolecular oxygen-tin contacts,
each of them being in a pseudotrans position to C(11)
and C(21). Hence, the overall geometry of 6a can be
regarded as that of a bicapped tetrahedron with a [4 +
2] coordination at tin. Such a structural arrangement
was observed previously for 1,4-bis({2,6-bis[(dimethyl-
amino)methyl]phenyl}dihydrosilyl)benzene.7f The Sn-O
distances of 3.006(4) and 3.022(3) Å are shorter than
the sum of the van der Waals radii of tin and oxygen
(3.700 Å)19 but far longer than the corresponding Sn-O
distances in 7.
(18) Vij, A.; Kirchmeier, R. L.; Willet, R. D.; Shreeve, J . M. Inorg.
Chem. 1994, 33, 5456.
(19) Bondi, A. J . Phys. Chem. 1964, 68, 441.

Penta- and Hexacoordinate Organotin(IV) Compounds
Organometallics, Vol. 17, No. 6, 1998 1231
Ta ble 1. Cr ysta llogr a p h ic Da ta for 6, 7, 9, 10, a n d 11
6
7
9
10
11
formula
fw
C
36H46O6P2Sn
C24H36Cl2O6P2Sn
672.06
C32H36O6P2Sn
697.24
C50H52O6P2Sn2
1048.24
C38H42Br2O6P2Sn2‚CH2Cl2
1138.78
755.36
cryst syst
cryst size, mm
space group
a, Å
b, Å
c, Å
monoclinic
orthorhombic
triclinic
monoclinic
monoclinic
0.20 × 0.13 × 0.13 0.15 × 0.13 × 0.13 0.25 × 0.15 × 0.15 0.30 × 0.15 × 0.15 0.13 × 0.10 × 0.10
P21/c
Pmn21
14.411(1)
11.237(1)
9.301(1)
90
P1h
C2/c
P21/n
14.806(1)
13.452(1)
37.351(1)
90
90.759(1)
90
7438.6(8)
8
1.349
10.736(1)
12.217(1)
13.813(1)
70.472(1)
84.815(1)
79.267(1)
1676.9(2)
2
21.825(1)
12.790(1)
19.101(1)
90
112.890(1)
90
4912.0(5)
4
1.417
14.555(1)
19.876(1)
17.424(1)
90
114.548(1)
90
4585.1(5)
4
1.650
R, Å
â, Å
90
90
γ, deg
V, Å3
1506.2(2)
2
1.482
Z
F
F
calcd, Mg/m3
measd, Mg/m3
1.381
1.394(2)
0.896
1.362(29)
0.814
3120
a
1.418(1)
1.127
2120
a
µ, mm-1
1.166
684
3.059
2240
F(000)
712
θ range, deg
4.78-20.92
-14 e h e 14
-12 e k e 12
-36 e l e 36
54 830
96.2
7511/0.074
4309
4.47-26.32
-17 e h e 17
-13 e k e 13
-10 e l e 10
21 468
94.3
4.53-23.91
-12 e h e 12
-13 e k e 13
-14 e l e 14
19 382
94.7
4884/0.040
3188
4.29-25.66
-26 e h e 26
-15 e k e 15
-20 e l e 19
34 158
93.4
4357/0.039
2952
4.63-21.97
-15 e h e 15
-20 e k e 20
-18 e l e 18
42 222
100.0
5558/0.047
3577
index ranges
no. of reflns collcd
completeness to θmax
no. of indep reflns/Rint
no. of reflns obsd with
(I > 2σ(I))
1597/0.037
1202
no. of refined params
849
183
0.956
0.0280
0.0510
<0.001
0.300/-0.421
399
0.888
0.0360
0.0704
<0.001
0.390/-0.333
276
0.923
0.0310
0.0651
0.001
516
0.894
0.0305
0.0601
0.001
GooF (F2)
0.860
0.0365
0.0537
0.001
R1 (F) (I > 2σ(I))
wR2 (F2) (all data)
(∆/σ)max
largest diff. peak/hole, e/Å3 0.351/-0.275
0.343/-0.464
0.478/-0.412
a
Not measured.
Ta ble 2. Selected In ter a tom ic Bon d Dista n ces (Å)
a n d An gles (d eg) for 6a , 6b, a n d 7
Å is remarkable. These Sn-O distances are comparable
to the corresponding values found for Me2SnCl2‚2HMPA
(Sn-O 2.231 Å),21 Et2SnCl2‚2Ph3PO (Sn-O 2.236, 2.258
Å),22a Et2SnCl2‚[Ph2(O)P]2(CH2)2 (Sn-O 2.277/2.285
Å),22b and Bu2SnCl2‚1,2-[Ph2(O)P]2(CH)2 (Sn-O 2.27/
2.29 Å).22c However, they are unambiguously shorter
than those in the complexes MeBr2SnCH2C(Me)[P(O)-
(Oi-Pr)2]2 (Sn-O 2.425/2.482 Å),22d Et2SnCl2‚[Me(i-
PrO)(O)P]2CH2 (Sn-O 2.417/2.497 Å),22e Ph2SnCl2‚
[(EtO)2(O)P]2CH2 (Sn-O 2.400/2.427 Å),22f {Me2SnCl2‚
[(EtO)2(O)P]2CHNMe2}2 (Sn-O 2.38/2.64 Å),22g and
{Me(Br)(Cl)SnCH2CH[P(O)(Oi-Pr)2]2}2 (Sn-O 2.427/
2.497 Å).22h The lengths of both the Sn-Cl and P-O
bonds in 7 of 2.5184(14) Å are of the same order of
magnitude than those in the complexes mentioned
above.
6a
6b*
7
X ) C(21);
Y ) C(31)
X ) C(21*);
Y ) C(31*)
X ) Cl(1);
Y ) Cl(1a)
Bond Distances
2.168(6)
2.139(7)
2.128(6)
2.094(6)
3.006(4)
3.022(3)
1.458(4)
1.462(4)
Sn(1)-C(1)
Sn(1)-C(11)
Sn(1)-X
2.159(5)
2.144(6)
2.160(5)
2.091(6)
3.063(4)
2.865(3)
1.461(4)
1.462(4)
2.129(7)
2.135(8)
2.518(1)
Sn(1)-Y
Sn(1)-O(1)
Sn(1)-O(2)
P(1)-O(1)
P(2)-O(2)
2.278(6)
2.203(5)
1.497(5)
1.506(5)
Bond Angles
C(1)-Sn(1)-C(11)
C(1)-Sn(1)-X
109.8(2)
104.7(2)
125.2(3)
100.3(3)
105.4(3)
109.2(3)
69.9(2)
69.7(2)
173.4(2)
72.6(2)
102.8(3)
113.0(2)
122.5(2)
96.3(2)
114.4(3)
104.8(3)
69.1(2)
73.5(2)
160.4(2)
73.5(2)
84.3(2)
169.2(2)
72.0(2)
174.9(3)
86.62(4)
C(1)-Sn(1)-Y
C(11)-Sn(1)-X
C(11)-Sn(1)-Y
X-Sn(1)-Y
93.50(4)
In 9, 10, and 11 the PdO groups are directed toward
the tin atoms, resulting in real structures along the
tetrahedron-trigonal bipyramid path. The position
along this path is given by the difference of the sums of
172.6(1)
79.3(2)
81.8(2)
C(1)-Sn(1)-O(1)
C(1)-Sn(1)-O(2)
C(11)-Sn(1)-O(1)
C(11)-Sn(1)-O(2)
X-Sn(1)-O(1)
X-Sn(1)-O(2)
Y-Sn(1)-O(1)
Y-Sn(1)-O(2)
O(1)-Sn(1)-O(2)
C(2)-P(1)-O(1)
C(6)-P(2)-O(2)
P(1)-O(1)-Sn(1)
P(2)-O(2)-Sn(1)
95.6(2)
103.3(2)
90.76(7)
88.12(8)
(20) J astrzebski, J . T. B. H.; van der Schaaf, P. A.; Boersma, J .; van
Koten, G.; de Wit, M.; Wang, Y.; Heidenrijk, D.; Stam, C. H. J .
Organomet. Chem. 1991, 407, 301.
(21) Rheingold, A. L.; Ng, S. W.; Zuckerman, J . J . Inorg. Chim. Acta
1984, 86, 179.
73.6(2)
167.4(2)
79.4(2)
83.0(2)
169.2(2)
118.7(1)
105.6(3)
113.3(3)
98.4(2)
(22) (a) Tursina, A. I.; Aslanov, L. A.; Chernyshev, V. V.; Medvedev,
S. V.; Yatsenko, A. V. Koord. Khim. 1985, 11, 1420. (b) Pelizzi, G.;
Tarasconi, P.; Pelizzi, C.; Molloy, K. C.; Waterfield, P. Main Group
Met. Chem. 1987, 10, 353. (c) Harrison, P. G.; Sharpe, N. W.; Pelizzi,
C.; Pelizzi, G.; Tarasconi, P. J . Chem. Soc., Dalton Trans. 1983, 1687.
(d) Hartung, H.; Krug, A.; Richter, F.; Weichmann, H. Z. Anorg. Allg.
Chem. 1993, 619, 859. (e) Lorberth, J .; Wocadlo, S.; Massa, W.;
Yashina, N. S.; Grigor’ev, E. V.; Petrosyan, V. S. J . Organomet. Chem.
1994, 480, 163. (f) Gielen, M.; Cardarelli, N. Antitumor Active Orga-
notin Compounds; CRC Press: Boca Raton, FL, 1987. (g) Lorberth, J .;
Shin, S.-H.; Otto, M.; Wocadlo, S.; Massa, W.; Yashina, N. S. J .
Organomet. Chem. 1991, 407, 313. (h) Freitag, S.; Herbst-Irmer, R.;
Richter, F. U.; Weichmann, H. Acta Crystallogr. 1994, C50, 1588.
112.8(1)
112.4(3)
112.4(3)
99.6(2)
161.1(2)
107.1(3)
108.5(3)
117.1(1)
116.1(3)
99.0(2)
103.3(2)
the O,C,O-tridentate ligand. A similar distortion was
found for {2,6-[bis(dimethylamino)methyl]phenyl}(4-
methylphenyl)tin diiodide.20 The unsymmetrical in-
tramolecular Sn-O coordination of 2.203(5) and 2.278(6)

1232 Organometallics, Vol. 17, No. 6, 1998
Mehring et al.
Ta ble 3. Selected In ter a tom ic Bon d Dista n ces (Å)
a n d An gles (d eg) for 9, 10, a n d 11
9 X ) C(31) 10 X ) C(31) 11 X ) Br(1)
Bond Distances
Sn(1)-C(2)
Sn(2)-C(6)
Sn(1)-C(11)
Sn(2)-X
Sn(1)-C(21)
Sn(2)-C(41)
Sn(1)-X
Sn(2)-Br(2)
Sn(1)-O(1)
Sn(2)-O(2)
P(1)-O(1)
P(2)-O(2)
2.171(4)
2.133(4)
2.120(4)
2.148(4)
2.803(3)
1.450(3)
2.167(3)
2.135(3)
2.119(4)
2.148(4)
2.793(2)
1.464(2)
2.178(5)
2.155(5)
2.123(6)
2.122(5)
2.121(6)
2.105(5)
2.6003(7)
2.5980(7)
2.379(3)
2.412(3)
1.482(4)
1.473(4)
Bond Angles
C(2)-Sn(1)-C(11)
C(6)-Sn(2)-X
C(2)-Sn(1)-C(21)
C(6)-Sn(2)-C(41)
C(2)-Sn(1)-X
C(6)-Sn(2)-Br(2)
C(11)-Sn(1)-C(21) 111.6(2)
C(41)-Sn(2)-X
C(11)-Sn(1)-X
Br(2)-Sn(2)-X
C(21)-Sn(1)-X
C(41)-Sn(2)-Br(2)
O(1)-Sn(1)-C(2)
O(2)-Sn(2)-C(6)
O(1)-Sn(1)-C(11)
O(2)-Sn(2)-X
O(1)-Sn(1)-C(21)
O(2)-Sn(2)-C(41)
O(1)-Sn(1)-X
O(2)-Sn(2)-Br(2)
P(1)-O(1)-Sn(1)
P(2)-O(2)-Sn(2)
115.8(2)
118.1(2)
100.7(2)
121.69(12)
108.66(12)
104.14(12)
114.17(12)
100.31(14)
105.8(2)
117.0(2)
116.2(2)
116.6(2)
120.6(2)
96.1(2)
96.5(2)
122.5(2)
119.1(2)
95.9(2)
96.2(2)
97.8(2)
97.5(2)
79.3(2)
79.2(2)
84.0(2)
84.4(2)
86.7(2)
86.1(2)
174.64(9)
175.42(9)
114.6(2)
112.6(2)
F igu r e 6. View along the aromatic ring of 6a and 7.
those observed for Me2(Cl)SnCH2CH[P(O)(Oi-Pr)2]2
(Sn-O 2.444 Å)25b and Me2(F)Sn(CH2)2P(O)Ph2 (Sn-O
2.454 Å).25c Shorter Sn-O distances were reported for
Me2(Br)Sn(CH2)2P(O)Ph-t-Bu (Sn-O 2.324 Å)25d and
Me2(Cl)Sn(CH2)3P(O)Ph2 (Sn-O 2.292 Å).25e
It is noteworthy that in [8-(dimethylamino)-1-naphthyl]-
triphenyltin6f the longest tin-carbon bond length is
observed for the carbon atom trans to the NMe2 donor
group, whereas in 9 and 10 the longest distances are
found for Sn(1)-C(2) (2.171(4)/2.167(3) Å), respectively.
The Sn-Br bond lengths of 2.6003(7) and 2.5980(7) Å
in 11 are longer than the Sn-Br single bond length of
2.49 Å23 as result of the intramolecular Sn-O interac-
tion.
104.4(2)
103.6(2)
73.84(12)
80.05(13)
77.77(13)
174.18(12)
107.46(14)
74.86(9)
78.00(10)
77.28(10)
176.96(13)
114.6(2)
Compounds 6, 7, and 9-11 show different deviations
from the plane defined by the aromatic carbons (Figure
6). Whereas 7 shows ideal planarity, the aromatic rings
in 6a and 6b are strongly distorted to the extent that
C(1) and C(1*) are displaced by 0.119(8) and 0.106(7)
Å, respectively, from that plane. The tin atoms (Sn(1)
in 6a , Sn(1*) in 6b) are displaced in the same direction,
and the corresponding phosphorus atoms are displaced
in the opposite direction.
The deviation of the tin atoms from the plane defined
by the aromatic ring is smaller for 9 and 11. It amounts
to 0.076(7) Å for 9 and 0.050(10)/0.032(10) Å (Sn(1)/
Sn(2)) for 11. For 10, the deviation (0.109(7) Å) is
comparable to those observed for 6a and 6b.
the equatorial and axial angles ∆∑(ν), which is 90° for
the ideal trigonal bipyramid and 0° for the ideal
tetrahedron.4b,c,23 It amounts to 36.8° for 9, 34.27° for
10, and 66.1°(Sn1)/65.7°(Sn2) for 11. Associated with
the position of 9, 10, and 11 along the tetrahedron-
trigonal bipyramid path are the different Sn-O interac-
tions classified as Pauling-type bond orders4c,24 of 0.07
(9), 0.08 (10), and 0.29(Sn1)/0.26(Sn2) (11). The devia-
tion of the tin atoms from the respective trigonal plane
amounts to 0.477 Å for 9 in the direction of C(21), 0.492
Å for 10 in the direction of C(31), and 0.245/0.250 Å for
11 in the direction of Br(1)/Br(2).
The weak Sn-O interactions in the tetraorganotin
compounds 9 and 10 are of the same order of magnitude
as those previously reported for SnMe3-1,4-CHD-
COOMe (Sn-O 2.781 Å),6g (Z)-17-[2-(triphenylstannyl)-
vinyl]-4-estren-17-ol (Sn-O 2.77 Å),6b (Z)-3,4,4-trimethyl-
1-(triphenylstannyl)-1-penten-3-ol (Sn-O 2.772 Å),6h
and (Z)-2-methyl-3-triphenylstannyl-3-pentene-2-ol
(Sn-O 3.012 Å).6i
Table 4 summarizes the IR ν(PdO) frequencies of 2
and 5-12 as well as the PdO and Sn-O distances of 6,
7, and 9-11. The data suggest that in 5 there seems
to be no Sn-O interaction because the ν(PdO) of 1250
cm-1 is very close to the values found for 2 and for the
noncoordinating PdO group in 9. Weak Sn-O contacts
such as those found in 6, 9, and 10 are reflected in a
slight decrease of the ν(PdO) to 1231-1233 cm-1
.
The strength of the Sn-O interactions in the penta-
coordinate triorganotin derivative 11 of 2.379(3) and
2.412(3) Å is similar to those reported for Me2(Cl)SnCH2-
SiMe2CH2P(O)(Oi-Pr)2 (Sn-O 2.371 Å)25a and 2-Ph2-
P(O)C6H4Sn(Cl)Me2 (Sn-O 2.357 Å)10b but greater than
Notably, IR spectroscopy is not able to distinguish the
small differences of the Sn-O distances measured for
6a and 6b by X-ray crystallography; only one absorption
was found.
(25) (a) Kolb, U.; Dra¨ger, M.; Fischer, E.; J urkschat, K. J . Orga-
nomet. Chem. 1992, 423, 339. (b) Richter, F.; Dargatz, M.; Hartung,
H.; Schollmeyer, D.; Weichmann, H. J . Organomet. Chem. 1996, 514,
233. (c) Preut, H.; Godry, B.; Mitchell, T. Acta Crystallogr. 1992, C48,
1894. (d) Weichmann, H.; Mu¨gge, C.; Grand, A.; Robert, J . B. J .
Organomet. Chem. 1982, 238, 343. (e) Mitchell, T. N.; Godry, B. J .
Organomet. Chem. 1996, 516, 133.
(23) Kolb, U.; Dra¨ger, M.; J ousseaume, B. Organometallics 1991,
10, 2737.
(24) (a) Pauling, L. The Nature of Chemical Bond, 3rd ed.; Cornell
University Press: Ithaca, NY, 1960; Chapter 7. (b) Dunitz, J . D. X-ray
Analysis and the Structure of Organic Molecules; Cornell University
Press: Ithaca, NY, 1979; Chapter 7.

Penta- and Hexacoordinate Organotin(IV) Compounds
Organometallics, Vol. 17, No. 6, 1998 1233
Ta ble 4. IR ν(P dO) F r equ en cies for 2 a n d 5-12
a n d Bon d Dista n ces (P dO, Sn -O) for 6, 7, a n d
9-11
as of the multiplicity of their Ci signals resulting from
31P coupling, we did not observe the 1J (119Sn-13C)
couplings.
A comparison of the 31P NMR chemical shifts (Table
5) indicates high-frequency shifts in case of substantial
Sn-O interactions (7, 8, 11, 12) but only very small shift
differences between non- and weakly coordinating PdO
groups (2, 5, 6, 9, 10).
ν(PdO)
compd
(cm-1
)
d (PdO) (Å)
d (Sn-O) (Å)
2
5
6
1255
1250
1233
1.458(4), 1.463(4) (6a ) 3.006(4), 3.022(3) (6a )
1.461(4), 1.462(4) (6b) 2.865(3), 3.063(4) (6b)
1
A remarkable feature in the H NMR spectrum of 11
7
8
1176
1178
1.497(5), 1.506(5)
2.278(6), 2.203(5)
is the extremely high-frequency shift of δ 10.2 ppm
3
(4J (1H-31P) 4 Hz, J (1H-119Sn) 59 Hz) of the proton in
9
1252, 1231 1.450(3), 1.450(3)
2.803(3)
10
11
12
1232
1180
1250, 1170
1.464(2)
1.482(4), 1.473(4)
2.793(2)
2.379(3), 2.412(3)
the ortho position to the tin atoms.
Exp er im en ta l Section
Stronger Sn-O interactions, as established for 7, 8,
and 11, are reflected in a considerable lowering of ν-
(PdO) to 1176-1180 cm-1. These results are in line
with previous observations on related compounds.10,25
Str u ctu r es in Solu tion . 119Sn chemical shifts and
1J (119Sn-13C) and 2J (119Sn-1H) coupling constants were
shown to be very sensitive measures for the elucidation
of the coordination numbers and geometries of organotin
compounds,2,5b,c,6,26-29 especially when comparisons were
made with compounds of very similiar substituent
patterns.
All solvents were dried and purified by standard procedures.
All reactions were carried out under an argon atmosphere
using Schlenk-tube techniques.
IR spectra (cm-1) were recorded on
a Bruker IFS 28
spectrometer. Bruker DPX-300 and DRX-400 spectrometers
were used to obtain 1H, 13C, 31P, 29Si, and 119Sn NMR spectra.
1H, 13C, 29Si, 31P, and 119Sn NMR chemical shifts δ are given
in ppm and were referenced to Me4Si, H3PO4 (80%), and Me4-
Sn, respectively. Elemental analyses were performed on a
LECO-CHNS-932 analyzer. Satisfactory elemental analyses
could not be obtained for the oils 3, 4, and 12. However, their
NMR spectra were unambiguous. 1,3-Bis(diethoxyphospho-
nyl)benzene (1) was prepared according to the literature.16
1,3-Bis(d ieth oxyp h osp h on yl)-5-ter t-bu tylben zen e (2).
To a suspension of 1,2-dibromo-5-tert-butylbenzene (20.00 g,
68.5 mmol) and NiBr2 (2.60 g, 11.9 mmol) was added dropwise,
at 160 °C, triethyl phosphite (28.20 mL, 177 mmol). The
reaction mixture was stirred at this temperature for 2 h, and
the resulting EtBr was distilled off. The crude product was
passed through a column (SiO2/EtOAc) and distilled to give
18.9 g (68%) of 2 as colorless oil, bp 148-151 °C (2.5 × 10-2
mmHg): 1H NMR (400 MHz, C6D6) δ 1.04 (t, 12H, CH3), 1.13
(s, 9H, CH3), 3.92-4.08 (complex pattern, 8H, CH2), 8.40 (dd,
3J (1H-31P) ) 15 Hz, 2H, H4/6-aryl), 8.63 (t, 3J (1H-31P) ) 13
Hz, H2-aryl); 13C{1H} NMR (100.63 MHz, CDCl3) δ 15.8 (s, 4C,
CH3), 30.7 (s, 3C, CH3), 34.7 (s, 1C, C), 62.0 (s, 4C, CH2), 128.5
(dd, 1J (13C-31P) ) 189 Hz, 3J (13C-31P) ) 15 Hz, 2C, C1,3), 131.6
Selected NMR data for 2 and 5-11 are listed in Table
5. The data of 5 are close to the corresponding values
reported for PhSnMe3 (δ 119Sn -29.4 ppm, J (119Sn-
13CH3) 347 Hz, 2J (119Sn-1H) 55 Hz), [8-(dimethylamino)-
1-naphthyl]trimethyltin6f (1J (119Sn-13CH3) 364 Hz), and
C6H4-P(O)Ph2-2-SnMe3-110 (δ 119Sn -40.2 ppm), unam-
biguously indicating tetrahedral tin.
30
1
Compounds 6, 9, and 10 show small to moderate low-
frequency 119Sn chemical shifts and slightly increased
1J (119Sn-13C) couplings with respect to the values found
for Ph4Sn (δ 19Sn -128.1 ppm,31 1J (119Sn-13CH3) 531
Hz32), allowing one to conclude that the weak Sn-O
interactions observed in the solid state are maintained
in solution.
As expected, strong Sn-O contacts associated with
octahedral and trigonal-bipyramidal configurations at
tin are observed in solutions of 7, 8, 11, and 12,
respectively. The 119Sn resonances observed for 7 and
8 are close to the values reported for Ph2SnX2‚2Bu3PO3b
(X ) Cl, δ 119Sn -472,-477; X ) Br, δ 119Sn -467,-
477 ppm) and are considerably low-frequency-shifted
with respect to tetrahedrally configurated Ph2SnX2 (X
) Cl, δ 119Sn -33; X ) Br, δ 119Sn -72.5 ppm).3b The
low-frequency 119Sn chemical shifts as well as the
1J (119Sn-13C) couplings of 822 and 826 Hz observed for
11 and 12 with respect to δ 119Sn of -40 ppm3b and
1J (119Sn-13C) of 595 Hz32 reported for Ph3SnBr provide
clear evidence for the presence of pentacoordinate tin
atoms. Because of the poor solubility of 7 and 8, as well
2
(t, J (13C-31P) ) 10 Hz, 1C, C2), 132.2 (complex pattern, 2C,
C
4,6), 151.6 (t, 3J (13C-31P) ) 14 Hz, 1C, C5); 31P{1H} NMR
(162.0 MHz, CDCl3) δ 18.9; IR (Nujol) ν(PdO) 1255 cm-1
.
Anal. Calcd for C18H32O6P2: C, 53.23; H, 7.88. Found: C,
53.00; H, 7.70.
2,4-Bis(d iet h oxyp h osp h on yl)-1-(t r im et h ylsilyl)b en -
zen e (3) a n d 2,4-Bis(d iet h oxyp h osp h on yl)-1,5-b is(t r i-
m eth ylsilyl)ben zen e (4). To a solution of 1,3-bis(diethoxy-
phosphonyl)benzene16 (3.85 g, 11.0 mmol) in 20 mL of THF
was added, at -78 °C, 30 mL of a 0.40 M solution of LDA (12
mmol) in hexane/diethyl ether (3:1). The reaction mixture was
stirred for 2 h at this temperature. Trimethylchlorosilane
(3.60 mL, 14 mmol) was added by syringe, and the suspension
was warmed to room temperature overnight and hydrolyzed
with 30 mL of water. The organic layer was separated and
dried over Na2SO4, and the solvent was removed in vacuo to
give an orange oil. Purification by column chromatography
(SiO2/EtOAc) afforded 0.25 g (5%) of 3 and 1.10 g (24%) of 4
as yellow oils.
(26) Wrackmeyer, B. In Annual Reports on NMR Spectroscopy;
Webb, G. A., Ed.; Academic Press: London, 1985; Vol. 16, p 291.
(27) J urkschat, K.; Schilling, J .; Mu¨gge, C.; Tzschach, A.; Meunier-
Piret, M.; von Meerssche, M.; Gielen, M.; Willem, R. Organometallics
1988, 7, 38.
(28) Otera, J . J . Organomet. Chem. 1981, 221, 57.
(29) Howard, W. F.; Crecely, R. W.; Nelson, W. H. Inorg. Chem.
1985, 24, 2204.
(30) Schaeffer, C. D.; Ulrich, S. E.; Zuckerman, J . J . Inorg. Nucl.
Chem. Lett. 1978, 14, 55.
(31) Holecek, J .; Nadvornik, M.; Handlir, K.; Lycka, A. J . Orga-
nomet. Chem. 1983, 241, 177.
3: 1H NMR (400 MHz, CDCl3) δ 0.27 (s, 9H, Me3Si), 1.18 (t,
12H, CH3), 3.92-4.02 (complex pattern, 8H, CH2), 7.68-7.75
3
(complex pattern, 2H, H5/6-aryl), 8.11 (t, J (1H-31P) ) 12 Hz,
1H, H3-aryl); 13C{1H} NMR (100.63 MHz, CDCl3) δ -0.3 (s,
3C, Me3Si), 15.2 (complex pattern, 4C, CH3), 61.9 (complex
pattern, 4C, CH2), 127.9 (dd, 1J (13C-31P) ) 189 Hz, 3J (13C-
31P) ) 14 Hz, 1C, C4), 133.4 (dd, 1J (13C-31P) ) 190 Hz, 3J (13C-
2
4
31P) ) 13 Hz, 1C, C2), 132.7 (dd, J (13C-31P) ) 9 Hz, J (13C-
(32) Mathiasch, B. Org. Magn. Reson. 1981, 17, 296.
31P) ) 3 Hz, 1C, C5), 134.6 (t, 2J (13C-31P) ) 11 Hz, 1C, C3),

1234 Organometallics, Vol. 17, No. 6, 1998
Ta ble 5. Selected 13C, 31P , a n d 119Sn NMR Da ta a for 2 a n d 5-12
Mehring et al.
δ (Ci)b
δ (C)c
δ (31P)
δ
119Sn
compd
(2J (13C-31P)
(1J (119Sn-13C))
(J (119Sn-31P))
(J (119Sn-31P))
2
5
6
7
8
18.2
21.5 (30)
20.7 (37)
27.1 (89)
156.1 (t) (24)
150.4 (t) (22)
172.4 (t) (18)
173.5 (t) (18)
152.7 (dd)f (19)
151.0g
-0.03 (387)
145.9 (591)
137.3e (d)
-39.4 (t) (31)
-186.1 (t) (38)
-424.8 (t) (91)
-432.3 (t) (87)
-149.8 (dd) (16, 28)
-147.1g
149.2 (d)
26.7 (87)
9
141.2 (577)
141.0 (571)
142.4 (822)
142.1 (826)
18.0, 20.7
20.5 (28, 24)
25.9 (15, 34)
17.6, 26.9 (d)
10
11
12
156.1g
-180.3g
155.5 (dd)h (19)
-191.2 (d) (19)
a
b
Chemical shifts δ in ppm, coupling constants J in Hertz. Abbreviations: d ) doublet, t ) triplet, dd ) doublet of doublets. Refers
to the tin-bound ipso-carbon of the P-substituted aryl. c Refers to the tin-bound carbon of the R groups (i.e., Me for 5 and Ph for 6-12).
Not measured. nJ (13C-31P) ) 4.5 Hz. 4J (13C-31P) ) 2 Hz. Complex pattern (AA′XX′ system). 4J (13C-31P) ) 3 Hz.
d
e
f
g
h
3
2
134.8 (dd, J (13C-31P) ) 14/19 Hz, 1C, C6), 149.4 (d, J (13C-
was dissolved in 100 mL of dichloromethane and stirred with
a solution of KF (10 g, 0.17 mol) in 50 mL of water. The
resulting precipitate of Ph3SnF was filtered, and the organic
layer was separated and dried over Na2SO4. Dichloromethane
was removed in vacuo, and the residue was recrystallized from
hexane, giving 3.0 g (27%) of 6 as colorless crystals, mp 140-
142 °C: 1H NMR (400 MHz, C6D6) δ 0.92 (t, 12H, CH3), 1.17
(s, 9H, CH3), 3.39-3.42 (complex pattern, 4H, CH2), 3.66-3.70
(complex pattern, 4H, CH2), 7.16-7.30 (complex pattern, 9H,
aromatics), 8.16 (d, 3J (1H-119Sn) ) 50 Hz, 6H, aromatics), 8.38
(complex pattern, 2H, aromatics); 13C{1H} NMR (100.63 MHz,
CDCl3) δ 16.0 (complex pattern, 4C, CH3), 31.0 (s, 3C, CH3),
34.8 (s, 1C, C), 61.7 (complex pattern, 4C, CH2), 127.3 (s,
4J (13C-119Sn) ) 12 Hz, 3C, Cpara), 127.5 (s, 3J (13C-119Sn) ) 54
Hz, 6C, Cmeta), 133.4 (complex pattern, 2C, C3,5), 137.0 (s,
2J (13C-119Sn) ) 37 Hz, 6C, Cortho), 138.1 (dd, 1J (13C-31P) ) 191
31P) ) 23 Hz, 1C, C1); 31P{1H} NMR (162.0 MHz, CDCl3) δ 17.7
(d, J (31P-31P) ) 7 Hz), 18.8 (d, J (31P-31P) ) 7 Hz); 29Si{1H}
4
4
NMR (79.49 MHz, CDCl3) δ -3.7 (d, J (31P-29Si) ) 4 Hz).
1
4: H NMR (400 MHz, CDCl3) δ 0.32 (s, 18H, Me3Si), 1.22
(t, 12H, CH3), 3.96-4.06 (complex pattern, 8H, CH2), 8.02 (t,
4J (1H-31P) ) 4 Hz, 1H, H6-aryl), 8.16 (t, J (1H-31P) ) 14 Hz,
3
1H, H3-aryl); 13C{1H} NMR (100.63 MHz, CDCl3) δ 0.4 (s, 6C,
Me3Si), 16.0 (complex pattern, 4C, CH3), 61.9 (complex pattern,
4C, CH2), 133.3 (dd, J (13C-31P) ) 191 Hz, J (13C-31P) ) 12
1
3
Hz, 2C, C2,4), 136.1 (t, J (13C-31P) ) 13 Hz, 1C, C3), 142.7 (t,
2
3J (13C-31P) ) 18 Hz, 1C, C6), 147.7 (complex pattern, 2C, C1,5);
31P{1H} NMR (162.0 MHz, CDCl3) δ 19.7; 29Si{1H} NMR (79.49
MHz, CDCl3) δ -0.3 (complex pattern because of AA′XX′
system).
[{2,6-Bis(d iet h oxyp h osp h on yl)-5-ter t-b u t yl}p h en yl]-
tr im eth yltin (5). To a solution of 2 (2.00 g, 4.9 mmol) in 20
mL of hexane/diethyl ether (4:1) was added, at -78 °C, 18 mL
of a 0.40 M solution of LDA (7.2 mmol) in hexane/diethyl ether
(4:1). The yellow suspension was stirred for 5 h at this
temperature, and a solution of Me3SnCl (1.00 g, 5.02 mmol)
in 10 mL of diethyl ether was added dropwise. The reaction
mixture was warmed to room temperature and stirred over-
night. The solvent was evaporated, and the residue was
dissolved in 50 mL of dichloromethane and treated with a
solution of KF (5.00 g, 0.85 mol) in 40 mL of water. The
organic layer was separated and dried over Na2SO4, and the
solvent was removed in vacuo. Column chromatography (SiO2/
EtOAc) of the residue afforded 800 mg (29%) of 5 as a colorless
solid, mp 100-104 °C: 1H NMR (400 MHz, CDCl3) δ 0.41 (s,
2J (1H-119Sn) ) 56 Hz, 9H, CH3), 1.30 (t, 12H, CH3), 1.33 (s,
9H, CH3), 3.99-4.16 (complex pattern, 8H, CH2), 7.94-7.98
(complex pattern, 2H, aromatics); 13C{1H} NMR (100.63 MHz,
Hz, J (13C-31P) ) 20 Hz, 2C, C2,6), 145.9 (s, J (13C-119/117Sn)
) 591/565, 3C, Cipso), 150.4 (t, 2J (13C-31P) ) 21 Hz, 1C, C1),
151.0 (t, 3J (13C-31P) ) 13 Hz, 1C, C4); 119Sn{1H} NMR (149.18
MHz, C6D6) δ -186.1 (t, J (119Sn-31P) ) 38 Hz); 31P{1H} NMR
(162.0 MHz, CDCl3) δ 20.7 (J (31P-119Sn) ) 37 Hz); IR (KBr)
ν(PdO) 1233 cm-1. Anal. Calcd for C36H46O6P2Sn: C, 57.27;
H, 6.09. Found: C, 57.30; H, 6.35.
[{2,6-Bis(d iet h oxyp h osp h on yl)-5-ter t-b u t yl}p h en yl]-
p h en yltin Dich lor id e (7). A suspension of 6 (193 mg, 0.26
mmol) in 7 mL of diethyl ether was treated with HCl gas at 0
°C for 2 h. The solvent was evaporated, and the resulting
residue was recrystallized from hexane/dichloromethane, giv-
ing 110 mg (63%) of 7 as colorless crystals, mp > 350 °C: 1H
NMR (400 MHz, CDCl3) δ 1.32 (t, 12H, CH3), 1.37 (s, 9H, CH3),
4.20-4.30 (complex pattern, 4H, CH2), 4.40-4.50 (complex
pattern, 4H, CH2), 7.30-8.24 (complex pattern, 7H, aromatics);
13C{1H} NMR (100.63 MHz, CDCl3) δ 16.2 (complex pattern,
4C, CH3), 31.2 (s, 3C, CH3), 35.3 (s, 1C, C), 65.5 (s, 4C, CH2),
124.6 (dd, 1J (13C-31P) ) 183 Hz, 3J (13C-31P) ) 17 Hz, 2C, C2,6),
3
1
CDCl3) δ -0.5 (s, J (13C-119/117Sn) ) 387/370, 3C, CH3), 16.7
1
(complex pattern, 4C, CH3), 31.3 (s, 3C, CH3), 35.0 (s, 1C, C),
62.4 (complex pattern, 4C, CH2), 133.3 (complex pattern, 2C,
3
4
128.3 (s, J (13C-119Sn) ) 144 Hz, 2C, Cmeta), 129.6 (s, J (13C-
119Sn) ) 27 Hz, 1C, Cpara), 131.7 (complex pattern, 2C, C3,5),
1
3
C
C
3,5), 138.8 (dd, J (C-P) ) 192 Hz, J (13C-31P) ) 22 Hz, 2C,
2
134.6 (s, J (13C-119Sn) ) 85 Hz, 2C, Cortho), 147.3 (t, nJ (13C-
2,6), 150.4 (t, J (13C-31P) ) 13 Hz, 1C, C4), 156.1 (t, J (13C-
3
2
31P) ) 4.5 Hz, 1C, Cipso), 153.7 (t, 3J (13C-31P) ) 13 Hz, 1C,
C4), 172.4 (t, 2J (13C-31P) ) 18 Hz, 1C, C1); 119Sn{1H} NMR
(149.18 MHz, CDCl3) δ -424.8 (t, J (119Sn-31P) ) 91 Hz); 31P-
{1H} NMR (162.0 MHz, CDCl3) δ 27.1 (J (31P-119Sn) ) 90 Hz);
IR (KBr) ν(PdO) 1176 cm-1. Anal. Calcd for C24H36Cl2O6P2-
Sn: C, 42.91; H, 5.36. Found: C, 42.85; H, 5.40.
31P) ) 24 Hz, 1C, C1); 119Sn{1H} NMR (149.18 MHz, CDCl3) δ
-39.4 (t, J (119Sn-31P) ) 31 Hz); 31P{1H} NMR (162.0 MHz,
CDCl3) δ 21.5 (J (31P-119Sn) ) 30 Hz); IR (KBr) ν(PdO) 1250
cm-1
. Anal. Calcd for C21H40O6P2Sn: C, 44.34; H, 7.03.
Found: C, 44.65; H, 7.40.
[{2,6-Bis(d iet h oxyp h osp h on yl)-5-ter t-b u t yl}p h en yl]-
tr ip h en yltin (6). To a solution of 2 (6.00 g, 14.8 mmol) in 50
mL of hexane/diethyl ether (4:1) at -78 °C was added 50 mL
of a 0.40 M solution of LDA (20 mmol) in hexane/diethyl ether
(4:1). Subsequent stirring for 6 h at -78 °C afforded a yellow
suspension. The precipitate was filtered and dried in vacuo
to give 3.0 g of the monolithiated complex C6H2[P(O)(OEt)2]2-
2,4-Li-1 (2a ) as a pale yellow solid. To a suspension of this
solid in 60 mL of diethyl ether was added, at -30 °C,
triphenyltin chloride (2.60 g, 6.8 mmol) portionwise. The
reaction mixture was stirred for 14 h, the precipitate was
filtered, and the solvent was evaporated in vacuo. The residue
[{2,6-Bis(d iet h oxyp h osp h on yl)-5-ter t-b u t yl}p h en yl]-
p h en yltin Dibr om id e (8). To a solution of 6 (174 mg, 0.23
mmol) in 8 mL of benzene/methanol (1:1) was added, at -20
°C, 4.18 mL of a 0.11 M methanolic bromine solution. Sub-
sequent stirring overnight afforded a pale yellow solution. The
solvent was evaporated, and the resulting residue was recrys-
tallized from hexane, giving 100 mg (56%) of 8 as a colorless
solid, mp > 350 °C: 1H NMR (400 MHz, CDCl3) δ 1.34 (t, 12H,
CH3), 1.38 (s, 9H, CH3), 4.20-4.34 (complex pattern, 4H, CH2),
4.43-4.52 (complex pattern, 4H, CH2), 7.31-8.18 (complex
pattern, 7H, aromatics); 13C{1H} NMR (100.63 MHz, CDCl3)

Penta- and Hexacoordinate Organotin(IV) Compounds
Organometallics, Vol. 17, No. 6, 1998 1235
δ 16.3 (complex pattern, 4C, CH3), 31.2 (s, 3C, CH3), 35.4 (s,
1C, C), 65.8 (s, 4C, CH2), 124.1 (dd, 1J (13C-31P) ) 184 Hz,
solution was stirred overnight, and the solvent was evaporated
in vacuo. The resulting colorless residue was washed several
times with small portions of hexane, giving 130 mg (86%) of
11 as a colorless solid, mp 231-233 °C: 1H NMR (300 MHz,
CDCl3) δ 1.10 (t, 12H, CH3), 3.72-3.91 (complex pattern, 8H,
CH2), 7.29-8.13 (complex pattern, 21H, aromatics), 10.17 (t,
4J (1H-31P) ) 4 Hz, 3J (119Sn-1H) 59 Hz, 1H, aromatic); 13C-
{1H} NMR (75.47 MHz, CDCl3) δ 16.1 (complex pattern, 4C,
CH3), 64.0 (complex pattern, 4C, CH2), 128.2 (s, 3J (13C-119Sn)
) 77 Hz, 8C, Cmeta), 129.2 (s, 3J (13C-119Sn) ) 16 Hz, 4C, Cpara),
3
3J (13C-31P) ) 17 Hz, 2C, C2,6), 128.3 (s, J (13C-119Sn) ) 142
Hz, 2C, Cmeta), 129.7 (s, 4J (13C-119Sn) ) 27 Hz, 1C, Cpara), 131.8
(complex pattern, 2C, C3,5), 134.0 (s, 2J (13C-119Sn) ) 86 Hz,
3
2C, Cortho), 149.2 (s, 1C, Cipso), 153.8 (t, J (13C-31P) ) 13 Hz,
1C, C4), 173.5 (t, 2J (13C-119Sn) ) 18 Hz, 1C, C1); 119Sn{1H}
NMR (149.18 MHz, CDCl3) δ -432.3 (t, J (119Sn-31P) ) 87 Hz);
31P{1H} NMR (162.0 MHz, CDCl3) δ 26.7 (J (31P-119Sn) ) 87
Hz); IR (KBr) ν(PdO) 1178 cm-1
.
Anal. Calcd for C24H36
-
2
1
Br2O6P2Sn: C, 37.89; H, 4.73. Found: C, 38.25; H, 4.95.
131.4 (t, J (13C-31P) ) 12 Hz, 1C, C2), 133.0 (dd, J (13C-31P)
) 186 Hz, 3J (13C-31P) ) 13 Hz, 2C, C2,4), 136.5 (s, 2J (13C-
119Sn) ) 54 Hz, 8C, Cortho), 142.4 (s, 1J (13C-119/117Sn) ) 822/
784, 4C, Cipso), 148.1 (t, 3J (13C-31P) ) 17 Hz, 1C, C6), 156.1
(complex pattern, 2C, C1,5); 119Sn{1H} NMR (149.18 MHz,
CDCl3) δ -180.7 (complex pattern); 31P{1H} NMR (162.0 MHz,
2,4-Bis(d ieth oxyp h osp h on yl)-1-tr ip h en ylsta n n ylben -
zen e (9) a n d 2,4-Bis(d iet h oxyp h osp h on yl)-1,5-bis(t r i-
p h en ylsta n n yl)ben zen e (10). To a solution of 1,3-bis-
(diethoxyphosphonyl)benzene (4.00 g, 11.4 mmol) in 120 mL
of hexane/diethyl ether (3:1) was added, at -78 °C, 80 mL of
a 0.40 M solution of LDA (32.0 mmol) in hexane/diethyl ether
(3:1). Subsequent stirring for 6 h at -78 °C afforded a red-
brown solution. Triphenyltin chloride (12.3 g, 32.0 mmol) was
added portionwise, and the reaction mixture was stirred for 2
h at -78 °C. After reaction mixture was warmed to room
temperature overnight, the solvent was removed in vacuo. The
residue was dissolved in 100 mL of dichloromethane and
treated with a solution of KF (20 g, 0.34 mol) in 60 mL of
water. The precipitate (Ph3SnF) was filtered off, the organic
layer was separated and dried over Na2SO4, and the solvents
were removed in vacuo. The residue was purified by column
chromatography (SiO2/EtOAc) followed by recrystallization
from hexane/dichloromethane, giving 500 mg (6%) of 9 (mp
174-176 °C) and 2.50 g (21%) of 10 (mp 236 °C) as colorless
crystals.
5
CDCl3) δ 25.8 (J (31P-119Sn) ) 34 Hz, J (31P-119Sn) ) 15 Hz);
IR (KBr) ν(PdO) 1180 cm-1. Anal. Calcd for C38H42Br2O6P2-
Sn2: C, 43.31; H, 3.9. Found: C, 43.65; H, 4.15.
2,4-Bis(d iet h oxyp h osp h on yl)-1-(b r om od ip h en ylst a n -
n yl)ben zen e (12). To a solution of 9 (204 mg, 0.29 mmol) in
4 mL of benzene/methanol (1:1) was added, at 0 °C, 3.24 mL
of a 0.09 M methanolic bromine solution. The solution was
stirred overnight, and the solvent was evaporated in vacuo.
The resulting oily residue was dissolved in 2 mL of CH2Cl2/
hexane (1:3). Slow evaporation of CH2Cl2 resulted in the
precipitation of 140 mg (69%) of 12 as a yellow oil, which was
separated from hexane by decantation: 1H NMR (400 MHz,
CDCl3) δ 1.04 (t, 6H, CH3), 1.24 (t, 6H, CH3), 3.66-3.79
(complex pattern, 4H, CH2), 3.99-4.10 (complex pattern, 4H,
CH2), 7.24-8.11 (complex pattern, 12H, aromatics), 8.84 (dt,
3
4J (1H-31P) ) 4 Hz, J (119Sn-1H) ) 67 Hz, 1H, aromatic); 13C-
1
9: H NMR (400 MHz, CDCl3) δ 1.10 (t, 6H, CH3), 1.32 (t,
3
{1H} NMR (75.47 MHz, CDCl3) δ 15.8 (d, J (13C-31P) ) 7 Hz,
6H, CH3), 3.65-3.76 (complex pattern, 2H, CH2), 3.78-3.86
(complex pattern, 2H, CH2), 4.05-4.21 (complex pattern, 4H,
CH2), 7.31-8.31 (complex pattern, 18H, aromatics); 13C{1H}
2C, CH3), 16.1 (d, 7 Hz, 2C, CH3), 62.2 (d, 3J (13C-31P) ) 6 Hz,
2C, CH2), 63.9 (complex pattern, 3J (C,P) ) 6 Hz, 2C, CH2),
3
3
128.2 (s, J (13C-119Sn) ) 75 Hz, 4C, Cmeta), 129.2 (s, J (13C-
119Sn) ) 17 Hz, 2C, Cpara), 130.7/131.25 (dd, 1J (13C-31P) ) 189/
187 Hz, 3J (13C-31P) ) 14/15 Hz, 2C, C2/4), 133.5 (t, 2J (13C-
3
NMR (100.63 MHz, CDCl3) δ 15.9 (d, J (13C-31P) ) 7 Hz, 2C,
CH3), 16.1 (d, 3J (13C-31P) ) 6 Hz, 2C, CH3), 62.1 (complex
3
pattern, 4C, CH2), 128.0 (s, J (13C-119Sn) ) 52 Hz, 6C, Cmeta),
31P) ) 12 Hz, 1C, C3), 135.3 (dd, J (13C-31P) ) 9 Hz, J (13C-
2
4
4
1
128.2 (s, J (13C-119Sn) ) 12 Hz, 1C, Cpara), 129.3 (dd, J (13C-
31P) ) 3 Hz, 1C, C5), 136.1 (s, 2J (13C-119Sn) ) 53 Hz, 4C, Cortho),
31P) ) 188 Hz, 3J (13C-31P) ) 13 Hz, 1C, C4), 133.7 (dd, 2J (13C-
138.3 (dd, J (13C-31P) ) 13/19 Hz, 1C, C6), 142.4 (d, J (13C-
3
1
31P) ) 9 Hz, J (13C-31P) ) 3 Hz, 1C, C5), 134.5 (t, J (13C-31P)
4
2
119/117Sn) ) 826/791 Hz, 2C, nJ (13C-31P) ) 5 Hz, Cipso), 155.5
) 12 Hz, 1C, C3), 137.0 (s, J (13C-119Sn) ) 39 Hz, 6C, Cortho),
2
(dd, J (13C-31P) ) 19 Hz, J (13C-31P) ) 3 Hz, 1C, C1); 119Sn-
2
4
137.4 (dd, 1J (13C-31P) ) 178 Hz, 3J (13C-31P) ) 14 Hz, 1C,
C2), 138.3 (dd, 3J (13C-31P) ) 13/18 Hz, 1C, C6), 141.2 (s,
1J (13C-119/117Sn) ) 577/552, 3C, Cipso), 152.7 (dd, 2J (13C-31P)
) 20 Hz, 4J (13C-31P) ) 2 Hz, 1C, C1); 119Sn{1H} NMR (149.18
MHz, CDCl3) δ -149.8 (dd, J (119Sn-31P) ) 27 Hz, 5J (119Sn-
31P) ) 16 Hz); 31P{1H} NMR (162.0 MHz, CDCl3) δ 18.0 (d,
4J (31P-31P) ) 4 Hz, 5J (31P-119Sn) ) 16 Hz), 20.7 (d, 4J (31P-
31P) ) 4 Hz, J (31P-119Sn) ) 27 Hz); IR (KBr) ν(PdO) 1251,
1231 cm-1. Anal. Calcd for C32H38O6P2Sn: C, 54.98; H, 5.44.
Found: C, 55.20; H, 5.50.
{1H} NMR (149.18 MHz, CDCl3) δ -191.2 (d, J (119Sn-31P) )
19 Hz); 31P{1H} NMR (162.0 MHz, CDCl3) δ 17.6 (d, J (31P-
4
31P) ) 8 Hz), 26.9 (d, J (31P-31P) ) 8 Hz); IR (Nujol) ν(PdO)
4
1250, 1170 cm-1
.
Cr ysta llogr a p h y. Intensity data for the colorless crystals
were collected on a Nonius KappaCCD diffractometer with
graphite-monochromated Mo KR radiation at 293 K. The data
collection covered the whole sphere of reciprocal space with
360 frames via ω-rotation (D/ω ) 1°) at 2 times 5 (6, 10), 10
(7, 9), and 30 s (11) per frame. The crystal-to-detector distance
was 2.6 (9, 10, 11), 2.7 (7), and 4.0 cm (6). Crystal decay was
monitored by repeating the initial frames at the end of data
collection. In analyzing the duplicate reflections, there was
no indication for any decay. The structure was solved by
direct-methods SHELXS8633 (Sheldrick, 1990) and successive
difference Fourier syntheses. Refinement applied full-matrix
least-squares methods SHELXL9334 (Sheldrick, 1993).
10: 1H NMR (400 MHz, CDCl3) δ 1.06 (t, 12H, CH3), 3.58-
3.68 (complex pattern, 4H, CH2), 3.70-3.80 (complex pattern,
4H, CH2), 7.15-8.35 (complex pattern, 32H, aromatics); 13C-
{1H} NMR (100.63 MHz, CDCl3) δ 16.0 (complex pattern, 4C,
CH3), 62.1 (complex pattern, 4C, CH2), 127.9 (s, 3J (13C-119Sn)
) 54 Hz, 6C, Cmeta), 128.2 (s, 3J (13C-119Sn) ) 12 Hz, 1C, Cpara),
2
1
134.7 (t, J (13C-31P) ) 12 Hz, 1C, C3), 136.0 (dd, J (13C-31P)
) 175 Hz, 3J (13C-31P) ) 13 Hz, 2C, C1,3), 137.1 (s, 2J (13C-
119Sn) ) 39 Hz, 6C, Cortho), 141.0 (s, 1J (13C-119/117Sn) ) 571/
545 Hz, 3C, Cipso), 148.2 (t, 3J (13C-31P) ) 17 Hz, 1C, C6), 151.0
(complex pattern, 2C, C1,5); 119Sn{1H} NMR (149.18 MHz,
CDCl3) δ -151.0 (complex pattern); 31P{1H} NMR (162.0 MHz,
CDCl3) δ 20.5 (J (31P-119Sn) ) 26 Hz); IR (KBr) ν(PdO) 1232
The H atoms were placed in geometrically calculated
positions and refined with common isotropic temperature
factors for alkyl and aryl H atoms (Halkyl, C-H 0.96 Å; Haryl
C-H 0.93 Å).
,
Disordered groups were found in 6 (OEt-group C48 (side
occupation factor (sof) 0.7), C48′ (sof 0.3) and t-Bu group C8*,
C10* (sof 0.6), C9*, C9′* (sof 0.5), C8′*, C10′ (sof 0.4)), 9 (OEt
cm-1
. Anal. Calcd for C50H52O6P2Sn2: C, 57.31; H, 4.96.
Found: C, 57.40; H, 5.15.
2,4-Bis(d ieth oxyp h osp h on yl)-1,5-bis(br om od ip h en yl-
sta n n yl)ben zen e (11). To a solution of 10 (150 mg, 0.14
mmol) in 4 mL of benzene/methanol (1:1) was added, at 0 °C,
3.54 mL of a 0.079 M methanolic bromine solution. The
(33) Sheldrick, G. M. Acta Crystallogr. 1990 A46, 467-473.
(34) Sheldrick, G. M. SHELXL93; University of Go¨ttingen: Go¨ttin-
gen, Germany, 1993.

1236 Organometallics, Vol. 17, No. 6, 1998
Mehring et al.
groups C43, C45, C47, C43′, C45′, C47′ (sof 0.5)), and 11 (OEt
groups C51, C53, C55, C58, C51′, C53′, C55′, C58′ (sof 0.5)).
Atomic scattering factors for the neutral atoms and real and
imaginary dispersion terms were taken from the International
Tables for X-ray Crystallography.35 The figures were created
by SHELXTL-Plus.36 Crystallographic data are given in Table
1, and selected bond distances and angles are given in Tables
2 and 3.
Ack n ow led gm en t. We are grateful to the Deutsche
Forschungsgemeinschaft and the Fonds der Chemischen
Industrie for financial support.
Su p p or tin g In for m a tion Ava ila ble: Tables of all coor-
dinates, anisotropic displacement parameters, and geometric
data for compounds 6, 7, 9, 10, and 11 and 1H, 13C, 29Si, 31P,
and 119Sn NMR spectra for compounds 3, 4, and 12 (41 pages).
Ordering information is given on current masthead page.
(35) International Tables for Crystallography Kluwer Academic
Publishers: Dordrecht, The Netherlands, 1992; Vol. C.
(36) Sheldrick, G. M. SHELXTL-PLUS, Release 4.1; Siemens Ana-
lytical X-ray Instruments Inc.: Madison, WI, 1991.
OM970847C