Solution and cross-polarization/magic angle spinning NMR investigation of intramolecular coordination Sn-N in some organotin(IV) C,N-chelates

Article abstract of DOI:10.1016/S0020-1693(01)00596-5

An intramolecular donor/acceptor Sn-N bonding connection in a set of triphenyl- and diphenyl-(halogeno)tin(IV) C,N-chelates, Ph₂XSnL, where Ph = C₆H₅, X = Ph, Cl or Br and L¹ = 2-(dimethylaminomethyl)phenyl-, C₆H₄(CH₂NMe₂)-2, and L² = 2,6-bis[(dimethylaminomethyl)phenyl]-, C₆H₃(CH₂NMe₂)₂-2,6, respectively, was studied by ¹¹⁹Sn, ¹⁵N, ¹³C and ¹H NMR spectroscopy in solution of non-coordinating solvent (CDCl₃) and by ¹¹⁹Sn cross-polarization/magic angle spinning NMR techniques in the solid-state. The existence of Sn-N coordination bonds was confirmed in studied compounds and their strengths were evaluated through the values of NMR spectra parameters of nuclei directly involved in Sn-N connection, namely by characteristic changes of chemical shifts δ(¹¹⁹Sn) and δ(¹⁵N) and values of J(¹¹⁹Sn, ¹³C) and J(¹¹⁹Sn, ¹⁵N) coupling constants. The set was extended by compound [2,6-C₆H₃(CH₂NMe₂)₂] PhSnCl₂ (5a), that is the decomposition product of compound [2,6-C₆H₃(CH₂NMe₂)₂] Ph₂SnCl (5). This 5a was characterized by NMR spectroscopy and its structure was estimated by X-ray diffraction techniques.

Full text of DOI:10.1016/S0020-1693(01)00596-5

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Inorganica Chimica Acta 323 (2001) 163–170
Note
Solution and cross-polarization/magic angle spinning NMR
investigation of intramolecular coordination SnꢀN in some
organotin(IV) C,N-chelates
c
Alesˇ Ru˚zˇicˇka a,*, Roman Jambor a, Jirˇ´ı Brus b, Ivana C´ısarˇova´ , Jaroslav Holecˇek a
a Department of General and Inorganic Chemistry, Faculty of Chemical Technology, Uni6ersity of Pardubice, Studentska´ 95,
CZ-532 10 Pardubice, Czech Republic
b Institute of Macromolecular Chemistry of Academy of Sciences of the Czech Republic, Heyro6sky sq. 2, 162 06 Prague 6, Czech Republic
c Faculty of Natural Sciences, Charles Uni6ersity in Prague, Hla6o6a 2030, 128 40 Prague 2, Czech Republic
Received 8 March 2001; accepted 13 July 2001
Abstract
An intramolecular donor/acceptor SnꢀN bonding connection in a set of triphenyl- and diphenyl-(halogeno)tin(IV) C,N-chelates,
Ph2XSnL, where Ph=C6H5, X=Ph, Cl or Br and L1=2-(dimethylaminomethyl)phenyl-, C6H4(CH2NMe2)-2, and L2=2,6-bis-
1
[(dimethylaminomethyl)phenyl]-, C6H3(CH2NMe2)2-2,6, respectively, was studied by 119Sn, 15N, 13C and H NMR spectroscopy in
solution of non-coordinating solvent (CDCl3) and by 119Sn cross-polarization/magic angle spinning NMR techniques in the
solid-state. The existence of SnꢀN coordination bonds was confirmed in studied compounds and their strengths were evaluated
through the values of NMR spectra parameters of nuclei directly involved in SnꢀN connection, namely by characteristic changes
of chemical shifts l(119Sn) and l(15N) and values of J(119Sn, 13C) and J(119Sn, 15N) coupling constants. The set was extended by
compound [2,6-C6H3(CH2NMe2)2]PhSnCl2 (5a), that is the decomposition product of compound [2,6-C6H3(CH2NMe2)2]Ph2SnCl
(5). This 5a was characterized by NMR spectroscopy and its structure was estimated by X-ray diffraction techniques. © 2001
Elsevier Science B.V. All rights reserved.
Keywords: C,N-chelates; NMR spectroscopy; Intramolecular interaction; X-ray diffraction
spectroscopy [4]. However, the direct and simple
method for the confirmation of this interaction and the
evaluation of its magnitude is missing. A new approach
based on the measurements of NMR spectral parame-
ters of nuclei directly involved in SnꢀN coordination
has been used in our department recently [5]. In this
paper, we would like to show the possible way of
donor/acceptor interaction SnꢀN evaluation, in case of
some C,N-chelates, using routine NMR measurements
(in solution of non-coordinating solvent (CDCl3) and in
1. Introduction
The organometallic compounds with the potentially
bi- or tridentate C,N-chelating ligands are extensively
studied due to their potential biological activity [1],
enhanced reactivity [2] and very interesting structures
[2,3]. The central metal atom can interact with nitrogen
donor centres from the other side(s) of ligand. The
existence of this intramolecular interaction in organ-
otin(IV) compounds in the solid-state has been proven
by X-ray diffraction techniques on single crystals and
indirectly confirmed also in solutions by 1H NMR
1
the solid-state using 119Sn, 15N, 13C and H NMR and
119Sn cross-polarization/magic angle spinning (CP/
MAS) NMR spectroscopy, respectively) on the set of
some organotin(IV) compounds (see Fig. 1 and Table
1).
* Corresponding author. Fax: +420-40-03 7068.
E-mail address: ales.ruzicka@upce.cz (A. Ru˚zˇicˇka).
0020-1693/01/$ - see front matter © 2001 Elsevier Science B.V. All rights reserved.
PII: S0020-1693(01)00596-5

164
A. Ru˚zˇicˇka et al. / Inorganica Chimica Acta 323 (2001) 163–170
2. Experimental
2.1. Syntheses
in vacuo, and resulting solid materials were recrystal-
lized from boiling toluene to give pure white solids. The
compounds 3 and 6 have been previously reported, but
the characterization was necessary, because of the dif-
ferent preparation methods. The compounds 5 and 5a
were prepared from the same starting compounds (Fig.
2), compound 5 was obtained, when the starting lithium
salt was added like a hexane suspension very quickly to
the hexane solution of diphenyl tin(IV)dichloride at the
low temperature (−40 °C) and the solvent was rapidly
removed in vacuo, while when the reaction was carried
out at the room temperature the compound 5a was
obtained. We propose, from the 119Sn NMR shift value,
that the compound 4 is a byproduct in this side reac-
tion. After heating a solution of 5 to approximately
40 °C for 10 min the decomposition products 5a and 4
as well as a yet unidentified insoluble material were
observed.
All experiments were carried out under anaerobic
conditions. Dimethylaminomethylbenzene, 1,3-bis-
(aminomethyl)benzene, 2,6-dimethylaniline, n-butyl-
lithium, triphenyltin chloride, diphenyltin dichloride
and diphenyltin dibromide were obtained from com-
mercial sources (Sigma-Aldrich). Toluene, benzene, n-
hexane, n-pentane and diethylether were dried over and
distilled from sodium wire, chloroform was dried over
and distilled from P2O5 and LiAlH4, respectively. The
compounds 1, 2, 3 and 6 were prepared by standard
methods [4] (e.g. ortho-lithiation of starting dimethyl-
aminomethylbenzene and 1,3-bis[(dimethylamino)-
methyl]benzene (for 6), respectively, using n-butyl-
lithium in diethylether/n-hexane solution). The result-
ing organolithium salts were filtered off, dissolved in
benzene and added to solutions of appropriate organ-
otin(IV) halides. The reaction mixtures were evaporated
2.1.1. Ph3Sn(C6H4CH2N(CH3)2) (1)
Yield 87%. m.p. 86–87 °C (Found: C, 66.86; H,
5.55; N, 2.84; Sn, 24.74. C27H27NSn requires C, 66.97;
1
H, 5.62; N, 2.89; Sn, 24.51.). H NMR (CDCl3): l 7.60
(d, aryl-H, 6H), l 7.28 (m, aryl-H, 10H), l 7.14 (m,
aryl-H, 3H), l 3.31 (s, NCH2-H, 2H), l 1.52 (s, CH3-H,
6H).
2.1.2. Ph2SnCl(C6H4CH2N(CH3)2) (2)
Yield 79%. m.p. 218–220 °C (Found: C, 56.89; H,
5.06; N, 3.26; Cl, 8.14; Sn, 27.00. C21H22NClSn requires
1
C, 56.99; H, 5.01; N, 3.16; Cl, 8.01; Sn, 26.82.). H
NMR (CDCl3): l 8.53 (d, aryl-H, 1H), l 7.73 (d,
aryl-H, 4H), l 7.46 (m, aryl-H, 2H), l 7.42 (m, aryl-H,
6H), l 7.22 (d, aryl-H, 1H), l 3.56 (s, NCH2-H, 2H), l
1.89 (s, CH3-H, 6H).
Fig. 1. Structural (ligands L1 and L2) and numbering (compounds 2
and 4 as example) scheme.
2.1.3. Ph2SnBr(C6H4CH2N(CH3)2) (3)
Table 1
Studied LSnR1R2R3 compounds
Yield 74%. m.p. 238–240 °C (Found: C, 51.72; H,
4.51; N, 2.83; Br, 16.52; Sn, 24.42. C21H22NBrSn re-
quires C, 51.79; H, 4.55; N, 2.88; Br, 16.41; Sn, 24.37.).
1H NMR (CDCl3): l 8.54 (d, aryl-H, 1H), l 7.70 (d,
aryl-H, 4H), l 7.50 (m, aryl-H, 2H), l 7.40 (m, aryl-H,
6H), l 7.18 (d, aryl-H, 1H), l 3.56 (s, NCH2-H, 2H), l
1.89 (s, CH3-H, 6H).
Compound
La
R1
R2
R3
1
2
3
4
5
5a
6
L1
L1
L1
L2
L2
L2
L2
Ph
Ph
Ph
Ph
Ph
Ph
Ph
Ph
Ph
Ph
Ph
Ph
Cl
Ph
Cl
Br
Ph
Cl
Cl
Br
2.1.4. Ph3Sn[C6H3(CH2NMe2)2-2,6] (4)
The compound 4 was obtained by reaction of 2,6-
bis[(dimethylamino)methyl]phenyllithium
Ph
a
L1=C6H4(CH2NMe2)-2, and L2=C6H3(CH2NMe2)2-2,6.
(prepared
by reaction of 2,6-bis[(dimethylamino)methyl]bromo-
benzene and n-butyllithium in diethylether solution at
the room temperature) with triphenyltin chloride in
diethylether solution. The reaction mixture was evapo-
rated in vacuo, and arising solid material was dissolved
in chloroform/hexane solution. The solution was set
aside at −40 °C for 24 h and the observed crystalline
solid material was filtered off and the stock liquor was
Fig. 2. Scheme of proposed reactions of lithium salt of L2 with
Ph2SnCl2 by different conditions ((a) and (b)).

A. Ru˚zˇicˇka et al. / Inorganica Chimica Acta 323 (2001) 163–170
165
evaporated in vacuo giving pure 4 as a white crystalline
solid in 56% yield. m.p. 86–93 °C (Found: C, 66.9; H,
6.6; N, 4.9; Sn, 21.6. C30H34N2Sn requires C, 66.57; H,
6.33; N, 5.18; Sn, 21.93.). H NMR (CDCl3): l 7.65 (d,
aryl-H, 6H), l 7.21 (m, aryl-H, 10H), l 7.12 (d, aryl-H,
2H), l 3.24 (s, NCH2-H, 4H), l 1.63 (s, CH3-H, 12H).
of deuteriochloroform and in the case of compound 5,
approximately 10 mg in 0.5 ml of benzene-d6. Appro-
1
priate chemical shifts were calibrated on: H-residual
1
peak of CHCl3 (l=7.25) or benzene (for 5) (l=7.16),
13C-residual peak of CHCl3 (l=77.00 ppm) or benzene
(for 5) (l=128.39), 15N-external nitromethane (l=
0.00 ppm), 119Sn-external tetramethylstannane (l=0.00
n
2.1.5. Ph2SnCl[C6H3(CH2NMe2)2-2,6] (5)
ppm). The J(119Sn, 15N) parameter was obtained from
The compound 5 was prepared by rapid addition of
a hexane suspension of 2,6-bis[(dimethylamino)methyl]-
phenyllithium into the hexane solution of diphenyltin
dichloride at −40 °C. The obtained suspension was
after 3 min of stirring rapidly evaporated in vacuo and
the resulting white precipitate was washed with large
volume of cold benzene. The filtrate was evaporated in
vacuo to give a pure white solid in 12% yield. m.p.
80 °C with decomposition (Found: C, 57.29; H, 5.16;
N, 5.26; Cl, 7.52; Sn, 24.77. C24H29N2ClSn requires C,
15N NMR spectra.
The solid-state 13C and 119Sn spectra of studied com-
pounds were recorded on Bruker DSX 200 spectrome-
ter equipped with a double-bearing CP/MAS probe at
the room temperature. The compounds were packed in
standard 4-mm ZrO2 rotor. The 119Sn Hartmann–Hahn
cross-polarization match was set with tetracyclohexyltin
1
using a H 90° pulse of 4 ms. Ramped (RAMP)/CP/
MAS [6,7] experiments were used with repetition delay
of 10 s and contact time was set to 2 ms. In each case
at least two spinning rates (4.5–9 kHz) were used to
identify the isotropic chemical shift. The number of
scans varied between 200 and 4000. The 13C and 119Sn
chemical shifts were calibrated indirectly by external
glycine (carbonyl signal l=176.03 ppm) and tetracy-
clohexyltin (l= −97.35 ppm), respectively. The 119Sn
NMR chemical shift was allocated approximately to
the centre of gravity of the signal.
1
57.69; H, 5.85; N, 5.61; Cl, 7.10; Sn, 23.75.). H NMR
(CDCl3): l 7.57 (d, aryl-H, 4H, 3J(119Sn, 1H)=67.0
Hz), l 7.34 (m, aryl-H, 7H), l 7.11 (d, aryl-H, 2H), l
3.69 (s, NCH2-H, 4H), l 1.97 (s, CH3-H, 12H). 13C
CP/MAS NMR (50.32 MHz, 300 K): l 44.83(CH3),
47.23(CH3), 64.03(CH2), 126.96(Ar), 128.47(Ar),
130.29(Ar),
132.87(Ar),
134.91(Ar),
135.65(Ar),
138.77(Ar), 143.40(Ar).
2.1.6. PhSnCl2[C6H3(CH2NMe2)2-2,6] (5a)
The compound 5a was obtained from the reaction of
2,6-bis[(dimethylamino)methyl]phenyllithium with
2.3. Crystallography
Measured single crystal was obtained by vapour dif-
fusion of n-hexane into the 5% dichloromethane solu-
tion of compound 5a. Crystal data for 5a:
C18H24N2Cl2Sn, M=457.98, monoclinic, space group
diphenyltin dichloride at the room temperature (see
above). This compound is a pure white solid in 62%
yield. m.p. 123–130 °C (Found: C, 47.16; H, 5.35; N,
6.04; Cl, 15.62; Sn, 25.85. C18H24N2Cl2Sn requires C,
P21/c (no. 14), a=16.3570(1), b=59.876(1), c=
1
3
,
,
47.21; H, 5.28; N, 6.12; Cl, 15.48; Sn, 25.91.). H NMR
7.9330(3) A, i=98.2060(6)°, U=7690.0(3) A , Z=16,
3
1
(CDCl3): l 8.44 (d, aryl-H, 2H, J(119Sn, H)=120.74
Hz), l 7.47 (m, aryl-H, 3H), l 7.27 (t, aryl-H, 1H), l
7.08 (d, aryl-H, 2H), l 3.96 (s, NCH2-H, 4H), l 2.67 (s,
CH3-H, 12H).
T=150(2) K, v=1.608 mm−1, graphite-monochro-
,
mated Mo Ka radiation u=0.71073 A, colourless bar
with dimensions approximately 0.22×0.18×0.13 mm3,
crystal mounted with epoxy glue on a glass fibre and
measured on Nonius Kappa CDD diffractometer, q
range for data collection 1.1–26.7°, empirical absorp-
tion correction applied (multiscan from symmetry-re-
lated measurements), 12 910 unique diffractions of
25 847 collected, 9747 diffractions with I\2|(I) were
regarded as observed, 12 910 diffractions used in refine-
ment of 429 parameters via full-matrix least-squares on
F2, final R indices for observed data: R=0.076, Rw=
0.197, for all data R=0.103, Rw=0.217, goodness-of-
2.1.7. Ph2SnBr[C6H3(CH2NMe2)2-2,6] (6)
Yield 82%. m.p. 197–203 °C (Found: C, 52.79; H,
5.16; N, 5.26; Br, 14.42; Sn, 22.37. C24H29N2BrSn re-
quires C, 52.98; H, 5.37; N, 5.15; Br, 14.69; Sn, 21.81.).
1H NMR (CDCl3): l 7.65 (d, aryl-H, 4H), l 7.58 (m,
aryl-H, 7H), l 4.01 (s, NCH2-H, 4H), l 2.26 (s, CH3-H,
12H).
2.2. NMR experiments
fit=1.067, largest residual peaks 2.965 and −1.596 e
−3
,
A
.
The solution state 119Sn, 15N, 13C and 1H NMR
spectra were acquired at 134.28, 36.56, 90.56 and
360.13 MHz, respectively, on Bruker AMX 360 NMR
spectrometer, using a 5 mm tuneable broad band probe
at 300 K. The samples were obtained by dissolving of
approximately 50–200 mg of each compound in 0.5 ml
The structure was solved by direct methods (SIR93
[8]) and refined by full-matrix least-squares on F2
(SHELXL97 [9]). Only heavy atoms (Sn and Cl) were
refined anisotropically, N and C isotropically and hy-
drogens were fixed in their calculated positions. The
crystal data are given in Table 3.

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A. Ru˚zˇicˇka et al. / Inorganica Chimica Acta 323 (2001) 163–170
Table 2
Relevant parameters of 119Sn, 15N and 13C NMR spectra of compounds 1–6 in deuteriochloroform and in the solid-state in the case of 119Sn at
300 K
Compound
l(15N) (ppm);
(nJ(119Sn, 15N)
(Hz))
l(119Sn)a
(ppm)
l(119Sn)iso
(ppm)
l(1H(CH2))
(ppm)
l(13C) (ppm); (nJ(119Sn, 13C) (Hz))
CH2
CH3
C(1)
C%(1)
L1H
1
2
3
−353.0
3.27
3.31
3.56
3.56
63.61
44.54
44.86
45.67
45.77
128.15
−351.0 (23.6)
−163.3
−177.1
−180.8
−159.3
−191.7
−196.5
65.25 (20.1)
64.68 (29.1)
64.74 (27.7)
138.37 (577.8)
137.32 (796.2)
136.69 (774.0)
141.94 (545.9)
141.36 (772.0)
141.75 (758.8)
−347.6(b)
−347.2 (69.36)
L2H
4
−353.7
3.38
3.24
3.69
3.96
4.01
64.22
45.26
44.72
47.59
46.71
46.81
129.81
−349.6 (18.0)
−201.9
−193.4
−257.5
−69.10
−211.3
−72.6
−260.0
−71.6
65.50 (24.5)
139.29 (640.9)
145.29 (547.9)
b
b
b
5c,d
5a
6
(b)
63.08 (b)
(b)
(b)
−345.5 (b)
−347.2 (b)
62.13 (65.1)
64.24 (35.2)
(b)
(b)
b
b
130.10 (696.4)
133.40 (688.7)
a
CDCl3.
Not found.
Explained in text.
Measured in benzene-d6.
b
c
d
The lower accuracy of structure parameters is caused
by unfavourable crystal properties. Due to very large
lattice parameter, the high number of diffraction should
be excluded, because of their overlapping. Also all four
symmetrically independent molecules are disordered
(especially in dimethylamino moieties), therefore, tem-
perature factors are rather high for low temperature
measurement. Regardless of these difficulties, the struc-
ture determination shows main features of molecular
geometry.
studied. These conclusions are also confirmed by the
existence of relatively high values of J(119Sn, 15N) and
by increase of J(119Sn, 15N), J(119Sn, 13C(CH2)),
1J(119Sn, 13C(1)) and 1J(119Sn,13C(1%)) coupling con-
stants, respectively, with increasing Lewis acidity of tin
centre.
In Table 2, there are listed solid-state 119Sn NMR
data for the compounds 1–6. All compounds display
one central signal consistent with the presence of only
one type of organotin(IV) particles in asymmetric units.
The very small Dl(119Sn) values (compared to solution
spectra) of approximately 5–15 ppm for 1–6 (except 5)
are clear indication that their solid-state structure is
retained in deuteriochloroform solution.
3. Results and discussion
1
The relevant parameters of 119Sn, 15N, 13C and H
The coordination geometry of central tin atom in
compound 1 is slightly distorted tetrahedron with
bonding angles C(1)ꢀSnꢀC(1) and C(1)ꢀSnꢀC(1%) being
approximately 110° and 107°, respectively (calculated
according to the literature [12] from coupling constants
NMR spectra of compounds 1–6 are collected in Table
2. Compared to the free amines L1H and L2H, respec-
tively, data for compounds 1–6 show, that introduction
of organotin(IV) substituents provides a downfield shift
of l(1H(CH2)) and l(1H(CH3)) NMR resonances of the
CH2N(CH3)2 groups and also downfield shift of l(15N)
values. The l(119Sn) chemical shift values of all com-
pounds 1–6 are significantly more highfield than those
of unsubstituted analoga tetraphenylstannane (−128.1
ppm) [10], triphenyltinchloride (−44.7 ppm) [10],
triphenyltin bromide (−59.8 ppm) [10] and diphenyltin
dichloride (−26.7 ppm) [11]. Furthermore, the differ-
ences in l(119Sn) and l(15N) chemical shift values of
substituted and unsubstituted analoga generally in-
crease with increasing Lewis acidity of the tin centre
(excluding compound 6—see later). On the basis of
these facts, it can be concluded, that there is some
interaction of one (or two) CH2N(CH3)2 donor sub-
stituent(s) with central tin atom in the compounds
1
1J(119Sn, 13C(1)) and J(119Sn, 13C(1%))). The SnꢀN in-
tramolecular interaction is probably very weak as fol-
lows from values of Dl(15N)=2.7 ppm (Dl(15N) means
the differences between l(15N) of appropriate com-
pound and the free ligand), J(119Sn, 15N)=23.6 Hz and
J(119Sn, 13C(CH2))=20.1 Hz. The isotropic 119Sn chem-
ical shift of 1 in the solid-state, liso=159.3 ppm, indi-
cates there is no difference between the solution and
solid-state structures. An unsymmetrical shape of the
central signal l(119Sn)iso is observed in 119Sn CP/MAS
NMR of compound 1. It probably corresponds to the
two overlapping signals with 1:2 ratio of their relative
intensities as a result of residual quadrupolar coupling
due to 14N (I=1) [13].

A. Ru˚zˇicˇka et al. / Inorganica Chimica Acta 323 (2001) 163–170
167
The four-coordinated tin in compound 4 is indicated
coupling constant and higher increase of the l(15N)
value (Dl(15N)=5.4 ppm) [5]. The J(119Sn, 15N) was
not detected because of relatively low solubility of 2.
The central signal pattern of 119Sn CP/MAS NMR
spectrum is six-line signal pattern with relative intensity
of each line of 1:2:1:2:2:4 in compound 2, which is
typically for compounds containing tin atom bonded to
two different quadrupolar nuclei (14N and 35,37Cl with
I=1 and 3/2, respectively) [16]. According to these
results of this analysis we can assume the trans-trigonal
bipyramidal geometry of tin atom in single crystals of
the compound 2 (see X-ray results for: chloro[2-
1
1
by J(119Sn, 13C(1)) and J(119Sn, 13C(1%)) coupling con-
stants (640.9 and 547.9 Hz, respectively). The moderate
upfield l(119Sn) chemical shift (vide supra) and slightly
1
increased J(119Sn, 13C(1)) coupling constant with re-
spect to the values found for Ph4Sn (531 Hz [12])
allowing one to conclude that the weak SnꢀN interac-
tion is present in CDCl3 solution of 4. This fact is
confirmed by small value of Dl(15N)=4.1 ppm and by
magnitude of J(119Sn, 15N) and J(119Sn, 13C(CH2)) cou-
pling constants (18.0 and 24.5 Hz, respectively). The
geometry of central tin atom was assigned as a dis-
torted (capped or dicapped) tetrahedron with bonding
angles C(1)ꢀSnꢀC(1%) and C(1)ꢀSnꢀC(1) 107° and 113°
[10], respectively, analogous CꢀSnꢀC% angles, obtained
from X-ray diffraction analysis on single crystal, in
compound (Me3Sn)2{C6[CH2N(Me)2]4-2,3,5,6} with
similar vicinity of central tin atom are 108.45°, 94.85°
and 109.28° (average 104.2°), those of CꢀSnꢀC are
113.36°, 120.51° and 107.27° (average 113.7°) [14]. The
119Sn CP/MAS NMR spectrum of 4 consists of a broad
nearly symmetrical central signal without distinct split-
ting. The fact that only a few spinning sidebands of
very low intensity are observed for 4, indicates there is
an almost tetrahedral geometry around tin in the solid-
state [15].
(dimethylaminomethyl)phenyl]dimethyltin
[4,17],
bromo[2-(dimethylaminomethyl)phenyl]methyl-phenyl-
tin [18] and bromo[2-(dimethylaminomethyl)phenyl]-
dimethyltin [19]) and solution (as mentioned above).
The 119Sn, 15N and 13C NMR spectra parameters for
compound 3 are analogous to the same values for
compound 2 and also the coordination geometry is
probably the same. The value of J(119Sn, 15N)=69.4
Hz is clear evidence of the SnꢀN coordination bond.
The coordination geometry of compound 3 was proven
by X-ray diffraction [18]. Only unresolved broad signal
(without distinct splitting suitable for any analysis) is
obtained in 119Sn CP/MAS NMR spectrum for 3,
which is probably caused due to the effective decou-
pling by fast 79,81Br relaxation (as explained by Harris
[15] splitting due to 119Snꢀ79,81Br interaction can only be
observed, when the and 79,81Br relaxation is sufficiently
slow).
The value of l(119Sn)= −177.1 ppm for compound
2 in the CDCl3 solution corresponds to the five-coordi-
nated triphenyltin(IV) compounds [10] with trigonal
bipyramidal geometry. The magnitude of calculated
bonding angles (C(1)ꢀSnꢀC(1) and C(1)ꢀSnꢀC(1%) are
123° and 121°, respectively) [12] shows, that the tin
atom coordination polyhedra is trans-trigonal bipyra-
mide with the carbon atoms C(1) and C(1%) in the
equatorial plane and more electronegative chlorine and
nitrogen atoms in the axial positions. The change in the
coordination and in the geometry going from 1 to 2 is
reflected also in the increase of J(119Sn, 13C(CH2))
The l(119Sn) chemical shift of compound 6 (−69.1
ppm) indicates the four-coordinated tin atom in this
1
compound. On the other hand, J(119Sn, 13C(1)) and
1J(119Sn, 13C(1%)) coupling constant values (694.4 and
688.7 Hz, respectively) and values of bonding angles
C(1)ꢀSnꢀC(1) and C(1)ꢀSnꢀC(1%) (117° and 116°, re-
spectively) are in agreement with trigonal bipyramidal
configuration. The similar situation is found in quasi-
planar triorganotin(IV) cations solvated or coordinated
more or less strongly with two donor particles from
both side of C3Sn plane completing thus deformed
trans-trigonal bipyramide structure [20]. Both NMR
parameters are agree with trans-trigonal bipyramidal
configuration of cation [Ph2SnL2]+ (compensed by sim-
ple anion Br−) that was determined by X-ray diffrac-
tion in similar compounds [4]. The J(119Sn, 15N)
coupling constant was not determined, due to a very
broad signal in 15N NMR spectrum in CDCl3 solution.
In 119Sn CP/MAS NMR spectra, there is splitting of
central signal into triplet (Fig. 3). This splitting have a
1:4:4 integral pattern [13], with the same distances
between the neighbouring signals of the central signal
(138 Hz). This pattern results from the dipolar interac-
tion and Zeeman’s effect of the 119Sn nucleus with 2
Fig. 3. 119Sn RAMP CP/MAS NMR spectrum of compound 6 and
detail of the central signal its (1:4:4).

168
A. Ru˚zˇicˇka et al. / Inorganica Chimica Acta 323 (2001) 163–170
strikingly downfield shifted (−72.6 ppm). On the basis
of these facts and known structure of 6, we can predict,
that the structure of 5 is analogous to compound 6 in
the solid-state (Fig. 4(B)). We propose, that SnꢀN
interaction is weaken and one of the nitrogen atoms
goes out of the tin coordination sphere and is replaced
by chlorine atom in solution. We assume fluxional
processes (changing of both N(CH3)2 and Cl groups) in
solution, analogously to literature [22], which can be,
by our opinion, the main reason of thermal unstability
of 5, which undergoes to compound 5a in almost all
solution.
Fig. 4. Proposed structure of 5 in solution ((A) and (A%)) and in the
solid-state (B).
equiv. quadrupolar 14N nuclei. This pattern, is the
direct proof of the ionic character of 6. The structure of
6 was proven by X-ray diffraction techniques [21].
The compound 5 is unstable at higher temperature
(above 30 °C) in almost all solvent. The NMR spectra
were obtained from low concentration (compound 5 is
rather insoluble) benzene-d6 sample. The 1H NMR
spectrum (300 K) reveals one set of signals for 5. The
upfield shift of l(119Sn) (−193.38 ppm—narrow peak)
is typical for five-coordinated triphenyl compounds and
it signalises the similar structure with compound 2 in
CDCl3 (fluxional process—one nitrogen atom is
bonded to the tin atom while the second nitrogen atom
from ligand is out of the coordination sphere of tin
atom; Fig. 4(A)). However, in 119Sn CP/MAS NMR
spectra, there is the same 1:4:4 tree-line pattern with
equidistant differences between neighbouring signals
approximately 108 Hz and this indicates the same ionic
structure [Ph2SnL2]+Cl− as in compound 6. Also
l(119Sn) chemical shift value of the compound 6 is
In compound 5a the tin atom is five or ‘4+2’-coordi-
nated (l(119Sn)= −257.5 ppm), due to relative strong
SnꢀN interaction. The increase of the intramolecular
SnꢀN interaction strength is also confirmed by the
relative high value of coupling constant nJ(119Sn,
13C(CH2)) (65.1 Hz) and by the downfield shift of the
l(15N) (Dl(15N)=5.5 ppm). The shape of coordination
polyhedra of central tin atom neighbourhood is either
trans-trigonal bipyramide with only one nitrogen atom
bounded to the tin centre (alternatively—only one set
1
of signals was found in 15N, 13C and H NMR spectra
for both dimethylaminomethyl groups due to fast ex-
change—on the NMR time scale) or distorted octahe-
dron. Only unresolved broad signal (without distinct
splitting suitable for any analysis) is obtained in 119Sn
CP/MAS NMR spectrum for 5a, which is probably
caused due to the effective decoupling by fast 35,37Cl
relaxation.
Fig. 5. View of four symmetrically independent molecules of 5a (PLATON [23], 30% probability ellipsoids).

A. Ru˚zˇicˇka et al. / Inorganica Chimica Acta 323 (2001) 163–170
169
Table 3
Selected bond distances (A) and bond angles (°) and dihedral angles
(°) of aromatic planes for four symmetrically independent
the compound 5, which is unstable and probably due to
dynamic processes in solution decomposes to diorgan-
otin(IV) compound 5a.
,
€
molecules of 5a
Bond lengths, angles n
,
(A, °)
5. Supplementary material
1
2
3
4
A full list of crystallographic data and parameters
including fractional coordinates is deposited under
CCDC No. 156543 at the Cambridge Crystallographic
Data Center, 12 Union Road, Cambridge, CB2 1EZ,
UK (fax: +44-1223-336-033; e-mail: deposit@ccdc.
cam.ac.uk).
Sn(n)ꢀC(n1)
Sn(n)ꢀC(n1%)
Sn(n)ꢀN(n2)
Sn(n)ꢀN(n1)
Sn(n)ꢀCl(n2)
Sn(n)ꢀCl(n1)
2.092(10) 2.099(9)
2.088(9) 2.090(10)
2.139(9) 2.144(10)
2.420(9) 2.426(10)
2.432(8) 2.407(11)
2.537(2) 2.544(2)
2.547(2) 2.551(3)
2.143(9)
2.402(8)
2.144(8)
2.391(8)
2.404(10) 2.426(8)
2.548(3)
2.538(3)
2.543(3)
2.560(3)
C(n1)ꢀSn(n)ꢀC(n1%) 176.8(4)
C(n1)ꢀSn(n)ꢀN(n2) 76.9(3)
C(n1%)ꢀSn(n)ꢀN(n2) 105.2(3)
C(n1)ꢀSn(n)ꢀN(n1) 76.7(4)
C(n1%)ꢀSn(n)ꢀN(n1) 101.1(3)
N(n2)ꢀSn(n)ꢀN(n1) 153.7(3)
177.0(3)
77.0(3)
100.1(3)
76.3(3)
106.7(3)
153.2(3)
88.2(3)
91.9(2)
89.8(2)
88.4(2)
88.1(3)
91.9(2)
91.6(2)
88.5(2)
177.6(4) 179.1(4)
76.5(3)
102.1(3) 101.9(4)
76.0(3) 76.9(4)
77.3(4)
Acknowledgements
105.4(3) 103.9(4)
152.4(3) 154.2(3)
The research was supported by the Grant Agency of
the Czech Republic (grant no. 203/00/0920) and by the
Ministry of Education of the Czech Republic (project
LN 00A028).
C(n1)ꢀSn(n)ꢀCl(n2)
85.6(3)
91.0(3)
90.9(2)
86.6(2)
89.2(3)
90.4(3)
92.9(2)
C(n1%)ꢀSn(n)ꢀCl(n2) 92.2(3)
N(n2)ꢀSn(n)ꢀCl(n2) 89.2(3)
N(n1)ꢀSn(n)ꢀCl(n2) 89.5(3)
91.47(18) 85.6(2)
C(n1)ꢀSn(n)ꢀCl(n1)
90.7(3)
88.2(3)
90.0(2)
95.8(2)
88.8(3)
91.6(3)
86.9(3)
C(n1%)ꢀSn(n)ꢀCl(n1) 91.5(3)
N(n2)ꢀSn(n)ꢀCl(n1) 89.6(2)
N(n1)ꢀSn(n)ꢀCl(n1) 89.9(3)
85.74(18) 93.8(3)
References
Cl(n1)ꢀSn(n)ꢀCl(n2) 176.30(10) 175.60(10) 177.21(9) 178.02(9)
€(n) 75.4(4) 73.6(3) 42.2(4) 74.3(3)
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