Synthesis of novel terdentate N,C,N′-coordinated butyltin(IV) complexes and their redistribution reactions with SnCl4

Article abstract of DOI:10.1016/j.jorganchem.2005.11.063

The Sn(IV) butyl complexes [Bu_nSnCl_{3 - n}(NCN)] (NCN = [C₆H₃(CH₂NMe₂)₂-2,6] ^-, n = 1 (1), 2 (2), 3 (3)) were prepared. Spectroscopic analysis of 1-3 by ¹H and ¹¹⁹Sn NMR gave evidence for the presence of intramolecular N → Sn interactions in solution. The molecular structure of 1, as determined by a single-crystal X-ray diffraction study, revealed that it contained a six-coordinate Sn(IV) center with intramolecular N → Sn coordination of both ortho-amine substituents. Addition of SnCl₄ to 1 resulted in the isolation of the HCl adduct [BuSnCl₃(NCN ⁺H)] (6). Reactions of 2 and 3 with SnCl₄ each resulted in the HCl salt [SnCl₄(NCN⁺H)] (8) and the corresponding butyltin chloride, Bu₂SnCl₂ and Bu₃SnCl, respectively. The formation of HCl adducts 6 and 8 was ascribed to transfer of the NCN ligand to SnCl₄ and the presence of HCl (from partial hydrolysis of the product or SnCl₄ during the work up procedure). The molecular structures of 6 and 8 have been determined through single-crystal X-ray diffraction and revealed the presence of a [BuSnCl₃(aryl)] ^- or [SnCl₄(aryl)]^- stannate anion, respectively, with in each case one coordinated ortho-amine function and one protonated amine moiety involved in N-H?Cl-Sn hydrogen bonding in both compounds (2.14 ? for 6 and 2.18 ? for 8).

Full text of DOI:10.1016/j.jorganchem.2005.11.063

Journal of Organometallic Chemistry 691 (2006) 1544–1553
www.elsevier.com/locate/jorganchem
Synthesis of novel terdentate N,C,N0-coordinated
butyltin(IV) complexes and their redistribution reactions with SnCl4
a
a
a
b
Sander H.L. Thoonen , Hein van Hoek , Elwin de Wolf , Martin Lutz ,
b
c,
a,1
Anthony L. Spek , Berth-Jan Deelman *, Gerard van Koten
a
Debye Institute, Organic Chemistry and Catalysis, Utrecht University, Padualaan 8, NL-3584 CH Utrecht, The Netherlands
Bijvoet Center for Biomolecular Research, Crystal and Structural Chemistry, Utrecht University, Padualaan 8, NL-3584 CH Utrecht, The Netherlands
b
c
Arkema Vlissingen B.V., R&D Department, P.O. Box 70, NL-4380 AB Vlissingen, The Netherlands
Received 29 November 2005; accepted 29 November 2005
Available online 10 January 2006
Abstract
The Sn(IV) butyl complexes [BunSnCl3 ꢀ n(NCN)] (NCN = [C6H3(CH2NMe2)2-2,6]ꢀ, n = 1 (1), 2 (2), 3 (3)) were prepared. Spectro-
1
scopic analysis of 1–3 by H and 119Sn NMR gave evidence for the presence of intramolecular N ! Sn interactions in solution. The
molecular structure of 1, as determined by a single-crystal X-ray diffraction study, revealed that it contained a six-coordinate Sn(IV) cen-
ter with intramolecular N ! Sn coordination of both ortho-amine substituents. Addition of SnCl4 to 1 resulted in the isolation of the
HCl adduct [BuSnCl3(NCN+H)] (6). Reactions of 2 and 3 with SnCl4 each resulted in the HCl salt [SnCl4(NCN+H)] (8) and the corre-
sponding butyltin chloride, Bu2SnCl2 and Bu3SnCl, respectively. The formation of HCl adducts 6 and 8 was ascribed to transfer of
the NCN ligand to SnCl4 and the presence of HCl (from partial hydrolysis of the product or SnCl4 during the work up procedure).
The molecular structures of 6 and 8 have been determined through single-crystal X-ray diffraction and revealed the presence of a
[BuSnCl3(aryl)]ꢀ or [SnCl4(aryl)]ꢀ stannate anion, respectively, with in each case one coordinated ortho-amine function and one proton-
˚
˚
ated amine moiety involved in N–Hꢁ ꢁ ꢁCl–Sn hydrogen bonding in both compounds (2.14 A for 6 and 2.18 A for 8).
ꢀ 2005 Elsevier B.V. All rights reserved.
Keywords: Pincer; Sn; Aryltin; Redistribution; Hydrogen bonding; Butyltin; NCN ligand
1. Introduction
tin(IV) compounds bearing intramolecularly coordinating
ligands are more reactive in such aryl- and alkyl-transfer
reactions [5]. The difference in reactivity is ascribed to the
increase in electron density at the tin(IV) center by the
donor substituent [5,6] For example, the single methylation
of PtCl2(COD) by [Me3Sn(NCN)] [5c] (Eq. (1)) requires
less forcing conditions than methylation with Me4Sn [3].
Tetraorganotins have a proven value as mild alkylating
and arylating agents. In the Stille coupling reaction, for
example, trialkylarylstannes are used to selectively couple
an aryl group with an organic halide or triflate [1]. The
reaction involves a transmetallation step in which the aryl
group of the stannane is transferred to the transition metal
center of the catalyst [2]. Such a transfer reaction is also
used for the selective monoalkylation [3] and monoaryla-
tion [4] of transition metal complexes. Compared to the
tetracoordinate tetraorganotins, penta- and hexacoordinate
[Cl]
NMe2
Me
Sn
NMe
2
Me
PtCl2(COD)
Sn
Me
+ PtCl(Me)(COD)
Me
Me
NMe2
NMe
2
ð1Þ
*
Corresponding author. Tel.: +31 0113 617225; fax: +31 0113 612984.
E-mail addresses: berth-jan.deelman@arkemagroup.com (B.-J. Deel-
As part of our interest in new routes for selective tin-
alkyl bond formation, we prepared the novel Sn(IV) butyl
complexes [BunSnCl3 ꢀ n(NCN)] (n = 1–3) bearing the
man), g.vankoten@chem.uu.nl (G. van Koten).
1
Fax: +31 030 2523615.
0022-328X/$ - see front matter ꢀ 2005 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2005.11.063

S.H.L. Thoonen et al. / Journal of Organometallic Chemistry 691 (2006) 1544–1553
1545
monoanionic aryldiamine ligand [C6H3(CH2NMe2)2-2,6]ꢀ
(NCN) and studied their structure in solution as well as
in the solid state [7]. The NCN pincer ligand has been
employed for many years in our group to prepare a wide
range of organometallic complexes of which some have
been applied successfully as catalysts [8], sensors [9], and
switches [10].
Since [Me3Sn(NCN)] reacts with Me3SnCl to give exclu-
sively Me4Sn and [Me2Sn(NCN)][Me3SnCl2] (Eq. (2)) [5c]
we expected that the novel NCN Sn(IV) butyl compounds
could selectively transfer one or more butyl groups to other
metal centers. To investigate their use as selective alkylat-
ing agents for the synthesis of other alkyltin compounds,
reactions of the (NCN)Sn(IV)-butyl complexes [BunSn-
Cl3 ꢀ n(NCN)] (NCN = [C6H3(CH2NMe2)2-2,6]ꢀ, n = 1
(1), 2 (2), 3 (3)) with SnCl4 were carried out.
cating the chemical equivalence of the two CH2NMe2 sub-
stituents of the NCN-pincer ligand on the NMR time scale.
The non-aromatic 1H resonances of the NCN ligand in 1–3
are shifted 0.3–0.8 ppm downfield compared to those of the
free C6H4(CH2NMe2)2-1,3 (Table 1). The magnitude of
these shifts is dependent on the number of butyl substitu-
ents. The largest downfield shifts are observed for 1 with
only one butyl substituent, while the smallest downfield
shifts are observed for 3 containing three butyl substitu-
ents. Since the change in the chemical shift for the NMe2
resonance is relatively large (0.3–0.8 ppm), the tin center
is most likely involved in a direct N ! Sn interaction.
The 119Sn NMR chemical shift of 1 (d ꢀ215.3), 2 (d
ꢀ44.2) and 3 (d ꢀ73.9), respectively, are significantly more
upfield than those of the stannanes SnCl2(n-Bu)(C6H5) (d
+22.2) [11], SnCl(n-Bu)2(C6H5) (d +90.0) [12] and Sn(n-
Bu)3(C6H5) (d +41.7) [13] (Table 1). The upfield shift
points towards an, at least partial, coordination of the
CH2NMe2 donor to the tin center. The largest upfield
119Sn NMR chemical shift observed for 1 is consistent with
a six-coordinate tin center. If only one N ! Sn interaction
was involved, a value close to d ꢀ94 would have been
expected [14]. For 1, the presence of two N ! Sn dative
interactions in the solid state was established by a single-
crystal X-ray crystallographic study (Fig. 1, vide infra).
The 119Sn NMR chemical shift of 2 is in close agreement
with that of five-coordinate triorganotin chloride [Me2Sn-
Cl{C6H4(CH2NMe(CH2)2NMe2)-2}] (d ꢀ45 in CDCl3)
[15]. Like closely related [Me2SnBr(NCN)] [16], 2 is
expected to be present as a five-coordinate species in which
the aryl moiety only serves as a bidentate C,N-coordinated
ligand. The fluxionality of the CH2NMe2 substituents in
such complexes has been demonstrated for several NCN-
pincer metal complexes [7a,16,17]. At room temperature,
[Me3SnCl2]
NMe2
Me
Sn
NMe2
Me
2 Me3SnCl
Sn
Me
+ Me4Sn
Me
Me
NMe2
NMe2
ð2Þ
2. Results and discussion
2.1. Synthesis and spectroscopic analysis of (NCN)Sn(IV)-
butyl complexes 1–3
The Sn(IV) butyl complexes [BunSnCl3 ꢀ n(NCN)] (n = 1
(1), 2 (2), 3 (3)) were prepared by reacting the butyltin chlo-
rides BunSnCl3 ꢀ n with [LiC6H3(CH2NMe2)2-2,6]2 in Et2O
at 0 ꢁC (Eq. (3)).
1
BunSnCl4-n
Et2O, 0oC
the H NMR spectrum of the NCN-pincer ligand of 2 dis-
played only one set of singlet CH2 and NMe2 resonances,
½ [Li(NCN)]2
[(NCN)Sn(Bu)nCl3-n]
1: n = 1
2: n = 2
3: n = 3
Table 1
Selected 1H and 119Sn NMR data for stannanes 1–3, their free ligand
precursor C6H4(CH2NMe2)2-1,3 and stannanes SnCl2(Bu)(C6H5),
SnCl(Bu)2(C6H5) and Sn(Bu)3(C6H5)a
NMe2
NCN =
Compound
d(1H)
d(119Sn)
CH2
NMe2
NMe2
(NCN)Hb
SnCl2(Bu)(C6H5)
SnCl(Bu)2(C6H5)
Sn(Bu)3(C6H5)
[BuSnCl2(NCN)] (1)
[Bu2SnCl(NCN)] (2)
[Bu3Sn(NCN)] (3)
3.12
–
–
1.94
–
–
–
ð3Þ
+22.2
+90.0
+41.7
ꢀ215.3
ꢀ44.2
ꢀ73.9
+56.5
+60.3
ꢀ294.9
Complexes 1–3 were isolated in 67–98% yield as white
solids. All three complexes were examined by 1H and
119Sn NMR spectroscopy in CDCl3 solutions. Since both
NMe2 substituents of the NCN-pincer ligand are in princi-
ple available for intramolecular N ! Sn coordination, the
presence of such interactions was studied by comparison
–
–
3.91
3.73
3.44
2.75
2.24
2.10
2.51
2.58
2.65
[Bu2Sn(NCN)][B(C6H5)4] (4) 3.72
[Bu2Sn(NCN)][CF3SO3](5)
[BuSnCl2(NCN)(HCl)] (6)
3.83
3.98
of the H and 119Sn NMR data of complexes 1–3 with
1
4.78 (CH2N+) 2.85 (N+Me2)
the data of the free arylamine C6H4(CH2NMe2)2-1,3 and
the stannanes SnCl2(Bu)(C6H5), SnCl(Bu)2(C6H5) and
SnBu3(C6H5) (Table 1).
[SnCl3(NCN)] (7)
[SnCl3(NCN)(HCl)] (8)
4.17
4.09
2.83
2.84
ꢀ265.3
ꢀ258.0
5.01 (CH2N+) 2.94 (N+Me2)
a
Both the CH2N and the NMe2 resonances of complexes
1–3 appear as one singlet in the H NMR spectrum, indi-
In CDCl3 at 298 K.
NCN = [C6H3(CH2NMe2)2-2,6]ꢀ.
1
b

1546
S.H.L. Thoonen et al. / Journal of Organometallic Chemistry 691 (2006) 1544–1553
(8) for 2 and 3. In the reaction of 2 and 3, also the forma-
C12
C11
tion of the corresponding butyltin chlorides, n-Bu2SnCl2
(>95%) and n-Bu3SnCl (87%) (1H NMR), respectively,
was observed (Scheme 1). To confirm the identity of the
product, an independent sample of 6 was prepared by
reacting 1 with one equivalent of HCl (Eq. (5)). Complexes
6 and 8 are most likely the result of partial hydrolysis of 1
and putative [SnCl3(NCN)] (7), respectively, affording HCl
that reacts with 1 or 7 to form the final product. Formation
of 6 and 8 is so predominant, despite the special care that
was taken to exclude water, that it cannot be dismissed
as a mere artifact of sub-optimal experimental conditions.
C10
C1
N2
C16
C5
C6
C14
Cl2
Sn
C15
C4
Cl1
C13
C2
C3
N1
C7
C8
C9
Me
Me
H
N
NMe2
Cl
Sn Bu
Fig. 1. Displacement ellipsoid plot (50% probability) of [n-BuSnCl2-
{C6H3(CH2NMe2)2-2,6}] (1). Hydrogen atoms have been omitted for
clarity.
Cl
Cl
Sn Bu
1 equiv. HCl in Et2O
benzene
ð5Þ
Cl
Cl
NMe2
NMe2
indicating a fast interchange of the two CH2NMe2 groups.
These resonances did not de-coalesce at lower temperatures,
not even at ꢀ80 ꢁC (CD2Cl2) indicating that the fluxional
process is fast and low in energy. The mechanism of this
process (associative or dissociative) remains unestablished.
It was observed previously that complexes of the type
[R2SnX(NCN)] are able to dissociate into the ionic com-
plexes [R2Sn(NCN)][X] (R = Me, X = Cl, Br; R = Ph;
X = Cl, Br) [5c,17,18]. To exclude this possibility, we pre-
pared ionic [Bu2Sn(NCN)][X] (X = BPh4 (4) and CF3SO3
(5)) (Eq. (4)) and compared their 119Sn NMR data with
that of 2 (Table 1). The ionic character of 4 in the solid
state was confirmed by an X-ray crystallographic study
(vide infra). The large difference in the 119Sn NMR data
of 4 and 5 (d +56.5 and d +60.3, respectively) compared
to that of 2 (d ꢀ44.2), ruled out [Bu2Sn(NCN)][Cl] as a
possible structure of 2.
1
6
The 1H NMR spectrum of 6 (25 ꢁC, CDCl3) displayed a
singlet and a doublet for the NMe resonances (d 2.51 and
2.85, respectively), indicating the chemical disparity of
the two CH2NMe2 donor substituents. Furthermore, a
broad low-field resonance at d 10.91 was assigned to the
ammonium proton. The 119Sn NMR chemical shift (d
ꢀ294.9) had shifted about 90 ppm upfield compared to 1,
in line with the sixfold coordination of the Sn center and
replacement of the –NMe2 donor by a chloride ion. The
geometry around the tin center was confirmed in the solid
state by a single-crystal X-ray crystallographic structure
determination (Fig. 4, vide infra).
For 8, one singlet (d 2.84) and one doublet (d 2.94) were
noticed for the NMe resonances in the 1H NMR spectrum.
The broad signal at d 9.78 is ascribed to the N+H reso-
nance. The resonances of the CH2NMe2 donor substituents
of 8 are all shifted 0.1–0.2 ppm downfield compared to
those of 6. This can be explained by the stronger electron
withdrawing tin center of 8. The molecular structure of 8
in the solid state was confirmed by an X-ray crystallo-
graphic structure determination (Fig. 6, vide infra).
[X]
NMe
NMe2
Bu
2
Bu
i or ii
Sn
Cl
2
Sn
Bu
Bu
ð4Þ
NMe2
Me2N
X = BPh4 (4), CF SO3 (5)
3
NMe2
(i) NaBPh4 , THF (ii) AgCF3SO3 , C6 H6
Cl
1 equiv. SnCl4
toluene or pentane
Cl
+ BunSnCl4-n
The 119Sn NMR chemical shift of 3 (d ꢀ73.9) is in good
agreement with that of closely related hexa-coordinate
[Me3Sn(NCN)] (d ꢀ86.9) [5c]. Because of the strong struc-
tural similarity as well as the comparable 119Sn NMR data,
we conclude that the tin center in 3 is six-coordinate as
well, albeit that the N ! Sn interactions are relatively
weak.
[(NCN)Sn(Bu)nCl3-n
]
Sn
Cl
2: n = 2
3: n = 3
NMe2
7
HCl
Me
Me
Cl
H
N
Cl
Cl
2.2. Reactions of 1–3 with SnCl4
Sn Cl
NMe2
Addition of one equivalent of SnCl4 to 1–3 at room
temperature resulted in the unexpected isolation of
[BuSnCl2(NCN)(HCl)] (6) for 1 and [SnCl3(NCN)(HCl)]
8
Scheme 1. Reaction of 2 and 3 with SnCl4.

S.H.L. Thoonen et al. / Journal of Organometallic Chemistry 691 (2006) 1544–1553
1547
The reaction of 2 with one equiv. of SnCl4 was also per-
formed in CDCl3 at room temperature and monitored by
1H and 119Sn NMR spectroscopy. After addition of SnCl4,
immediate formation of equimolar amounts of n-Bu2SnCl2
and 7 along with traces of 8 (<5%) was observed. The 119Sn
1
and H NMR data of 7 (Table 1) are in close agreement
with hexa-coordinate 1. Next to n-Bu2SnCl2, no other
butyltin species were observed. The reaction of 3 with
SnCl4 is believed to involve intermediate 7 as well.
The reactions of 2 and 3 with SnCl4, either involve butyl
group transfer or transfer of the NCN-pincer ligand to
SnCl4. Butyl group transfer from 2 and 3 would initially
result in 1 and 2 as intermediates, respectively, along with
n-BuSnCl3 for 2 and n-Bu2SnCl2 for 3. As none of these
intermediates were observed, reaction of 2 and 3 with
SnCl4 appears to involve direct NCN ligand/Cl exchange.
This is remarkable given the chelating nature of the NCN
ligand and its general resistance to undergo transfer reac-
tions. However, initial complexation of the strong Lewis
acid SnCl4 with one of the NMe2 moieties, followed by
intramolecular aryl/Cl exchange – the latter being generally
facile for regular aryl groups – may very well offer a low
activation energy pathway for this process.
Fig. 3. Quaternion fit [28] of the four independent molecules in the crystal
structure of [n-BuSnCl2{C6H3(CH2NMe2)2-2,6}(HCl)] (6). CH hydrogen
atoms are omitted for clarity.
C9
C7
C3
C2
C8
N1
C4
Cl1
C1
2.3. Solid state structures of complexes 1, 4, 6 and 8
C5
C14
C6
To investigate the N ! Sn interactions of complexes 1,
4, 6 and 8 in the solid state, X-ray crystal structure deter-
minations have been carried out (Figs. 1–6, respectively).
Selected bond distances and bond angles of 1, 4, 6 and 8
are presented in Table 2.
Sn
C13
C15
C10
Cl3
Cl2
C16
H2N
C12
N2
C11
C20A
Fig. 4. Displacement ellipsoid plot (50% probability) of [n-BuSnCl2-
{C6H3(CH2NMe2)2-2,6}(HCl)] (6). CH hydrogen atoms are omitted for
clarity.
C19
C12
C18
C11
The molecular geometry of triorganotin 1 (Fig. 1)
shows a six-coordinated tin center with both CH2NMe2
donor substituents involved in intramolecular N ! Sn
interactions. The distortion of the octahedral ligand array
around the tin(IV) center arises from the large deviation
in the N(1)–Sn–N(2) bond angle (151.09(4)ꢁ) due to the
chelation of the pincer ligand. The Sn–N bond distances
are similar in length, indicating that the two CH2NMe2
donor substituents have N ! Sn interactions of the same
strength. The bond distance between the Cipso atom (C(1))
of the NCN-pincer ligand and the tin center (2.0967
C17
C10
C5
C6
N2
C1
C4
Sn
C8
C3
C2
C7
C13
C14
N1
C9
C15
˚
(15) A) is comparable to those of related [(4-tolyl)SnI2-
˚
˚
{C6H3(CH2NMe2)2-2,6}] (2.109(9) A) [19] and [PhSnCl2-
C16
{C6H3(CH2NMe2)2-2,6}] (2.092(10) A) [17]. The Sn–C(13)
˚
bond length (2.1355(16) A) is in close agreement with
Fig. 2. Displacement ellipsoid plot (50% probability) of [n-Bu2Sn{C6H3-
(CH2NMe2)2-2,6}][B(C6H5)4] (4). Hydrogen atoms, the tetraphenyl boron
anion, and the CH2Cl2 solvent molecule have been omitted for clarity.
Only the major conformation of the disordered atom C20 is shown.
the length found for the methyl substituent in trans
position to the Cipso atom of the C2N4 ligand in [(SnMe3)2-
˚
{C6(CH2NMe2)-2,3,5,6}] (2.139(3) A) [18b]. The bond

1548
S.H.L. Thoonen et al. / Journal of Organometallic Chemistry 691 (2006) 1544–1553
Table 2
Selected bond distances and bond angles for 1, 4, 6, and 8
˚
Bond distance (A)
Bond angles (ꢁ)
Compound 1
Sn–C(1)
2.0967(15)
2.1355(16)
2.4564(13)
2.4441(13)
2.5695(4)
2.5513(4)
Cl(1)–Sn–Cl(2)
N(1)–Sn–N(2)
C(1)–Sn–C(13)
N(1)–Sn–C(1)
N(2)–Sn–C(1)
Cl(1)–Sn–C(1)
Cl(2)–Sn–C(1)
175.649(14)
151.09(4)
173.87(6)
75.26(5)
75.82(5)
91.38(4)
Sn–C(13)
Sn–N(1)
Sn–N(2)
Sn–Cl(1)
Sn–Cl(2)
91.69(4)
Compound 4
Sn–C(1)
Sn–C(13)
Sn–C(17)
Sn–N(1)
2.101(2)
2.134(3)
2.136(2)
2.4173(17)
2.4393(18)
N(1)–Sn–N(2)
N(1)–Sn–C(13)
N(1)–Sn–C(17)
N(1)–Sn–C(1)
C(1)–Sn–C(13)
C(1)–Sn–C(17)
C(13)–Sn–C(17)
150.72(6)
99.10(8)
97.51(7)
75.33(7)
126.50(8)
120.44(8)
113.06(8)
Sn–N(2)
Compound 6a
Sn–C(1)
Sn–C(13)
Sn–N(1)
Sn–Cl(1)
Sn–Cl(2)
Sn–Cl(3)
N(2)–H(2N)
H(2N)ꢁ ꢁ ꢁCl(3)
N(2)ꢁ ꢁ ꢁCl(3)
2.179(4)
2.129(4)
2.419(4)
2.4811(9)
2.5182(12)
2.8015(10)
1.03(4)
N(1)–Sn–C(1)
N(1)–Sn–C(13)
N(1)–Sn–Cl(1)
N(1)–Sn–Cl(2)
N(1)–Sn–Cl(3)
C(1)–Sn–C(13)
C(1)–Sn–Cl(1)
C(1)–Sn–Cl(2)
C(1)–Sn–Cl(3)
N(2)–H(2N)ꢁ ꢁ ꢁCl(3)
77.42(14)
89.09(14)
86.60(8)
178.90(9)
94.26(8)
160.99(15)
92.34(10)
101.91(11)
84.54(10)
155(3)
Fig. 5. Quaternion fit [28] of the two independent molecules in the crystal
structure of [SnCl3{C6H3(CH2NMe2)2-2,6}(HCl)] (8). CH hydrogen
atoms have been omitted for clarity.
2.14(4)
3.109(4)
C3
C7
C2
Compound 8b
Sn–C(1)
Sn–N(1)
Sn–Cl(1)
Sn–Cl(2)
Sn–Cl(3)
Sn–Cl(4)
N(2)–H(2)
H(2)ꢁ ꢁ ꢁCl(1)
N(2)ꢁ ꢁ ꢁCl(1)
C4
C9
N1
2.169(3)
2.351(2)
2.5513(7)
2.4515(8)
2.4073(8)
2.4349(8)
0.91
N(1)–Sn–C(1)
N(1)–Sn–Cl(1)
N(1)–Sn–Cl(2)
N(1)–Sn–Cl(3)
N(1)–Sn–Cl(4)
C(1)–Sn–Cl(1)
C(1)–Sn–Cl(2)
C(1)–Sn–Cl(3)
C(1)–Sn–Cl(4)
Cl(1)–Sn–Cl(2)
N(2)–H(2)ꢁ ꢁ ꢁCl(1)
78.70(9)
95.63(6)
84.98(6)
86.77(6)
172.73(6)
88.66(7)
95.78(7)
162.48(7)
104.44(8)
175.55(3)
179
C8
C5
Cl2
C1
C6
Sn
2.18
3.091(3)
C10
Cl3
a
Only the first of four independent molecules is considered.
Only the first of two independent molecules is considered.
b
Cl4
Cl1
C11
H2
N2
˚
2.4173(17) and 2.4393(18) A, respectively, are similar to
those reported for [Me2Sn{C6H3(CH2NMe2)2-2,6}][Br]
C12
˚
(2.41 and 2.56 A) [18a], [Ph2Sn{C6H3(CH2NMe2)2-2,6}]-
Fig. 6. Displacement ellipsoid plot (50% probability) of [SnCl3{C6H3-
(CH2NMe2)2-2,6}(HCl)] (8). CH hydrogen atoms and disordered solvent
molecules have been omitted for clarity.
˚
[Br(H2O)] (2.4398(14) A) [18b] and [Me2Sn{C6H3(CH2N-
˚
Me2)2-2,6}][Li(H2O)4][Br][Cl] (2.36(2) and 2.45(2) A) [20].
Also the Sn–C bond distances are essentially comparable
to those of the strongly related [Me2Sn{C6H3(CH2N-
Me2)2-2,6}][Br] complex [18a]. Because of the flexible
butyl moiety, some disorder in the position of the d-C
atom is found. The bond angles and the bond distances
found for the tetraphenyl boron anion are as expected.
The zwitterionic diorganotin complex 6 crystallizes in
the chiral space group P21 with four independent molecules
in the asymmetric unit. The independent molecules essen-
tially differ only in the conformation of the n-butyl ligand
(Fig. 3). We therefore discuss only the geometry of the first
distances as well as the bond angles of the NCN-pincer
moiety are unexceptional.
The molecular geometry of ionic triorganotin
4
(Fig. 2) is distorted trigonal bipyramidal and is formed
by the three C atoms in the equatorial plane and the
two N atoms. The distortion of the trigonal bipyramidal
geometry results from the small N(1)–Sn–N(2) angle of
150.72(6)ꢁ. The sum of the C–Sn–C angles in the equato-
rial plane equals 360.00(8)ꢁ. The tin–nitrogen distances of

S.H.L. Thoonen et al. / Journal of Organometallic Chemistry 691 (2006) 1544–1553
1549
independent molecule. The molecular geometry, depicted
in Fig. 4, shows a distorted octahedral arrangement of
the six ligands (one N atom, two C atoms and three Cl
atoms) around the tin(IV) center. The distortion of the
geometry coordination sphere arises from the C(1)–Sn–
C(2) bond angle (160.99(15)ꢁ) which deviates significantly
from the ideal 180ꢁ. As was concluded from the 1H
NMR data, one CH2NMe2 donor substituent is coordi-
nated to the tin center via an N ! Sn interaction while
the other has accepted a proton and is present as CH2-
N+HMe2.
transferred which results in the formation of [SnCl3(NCN)]
(7) and the corresponding butyltin chloride. Due to unde-
sired hydrolysis of 7 or the presence of remaining SnCl4
during the work-up procedure, 7 was isolated as its HCl
adduct 8. These results demonstrate that the ortho-
CH2NMe2 donor substituents have no influence on the
transfer reactions of 2 and 3 with SnCl4 since these species
react in the same way with SnCl4 as the tetrahedral stann-
anes SnCl3 ꢀ n(n-Bun)(C6H5) that lack intramolecular donor
substituents.
˚
The Sn–Cl(3) bond (2.8015(10) A) is significantly longer
4. Experimental
than the other two Sn–Cl bonds (2.5182(12) and
˚
2.4811(9) A). This can be explained by the intramolecular
4.1. General comments
˚
Hꢁ ꢁ ꢁCl(3) bond interaction of 2.15(4) A. Such an increase
of the Sn–Cl bond distance was not observed for
[C2H5SnCl4(pyridine)](pyridineH) [21]. with intermolecular
Hꢁ ꢁ ꢁCl bonds. Except for the Sn–Cl(3) bond of 6, all other
tin–ligand bond distances are comparable to those found
for 1.
All reactions and manipulations were carried out under
an inert N2 atmosphere using standard Schlenk techniques.
All solvents were dried and distilled prior to use.
[LiC6H3(CH2NMe2)2-2,6]2 was prepared according to the
literature procedures [23]. Commercial anhydrous SnCl4,
n-BuSnCl3, n-Bu2SnCl2 and n-Bu3SnCl were used as sup-
The mono-organotin complex 8 crystallizes with two
independent molecules in the asymmetric unit. The inde-
pendent molecules have a very similar conformation
(Fig. 6). We therefore discuss only the geometry of the first
independent molecule. The molecular geometry is similar
to that of 6, also shows a hexa-coordinated tin center with
one CH2NMe2 donor substituent coordinated to the tin
center via a N ! Sn interaction (Fig. 6). The tin(IV) center
has a distorted octahedral ligand array that arise from
bonding interactions with C(1), the four chloride substitu-
ents and the N-donor atom of the CH2NMe2 substituent.
The distortion in the octahedral ligand array is the result
of the five membered ring (Sn, C(1), C(2), C(7), N(1)) with
a N(1)–Sn–C(1) bond angle of 78.70(9)ꢁ. As was observed
for 6, the Cl atom involved in the intramolecular Hꢁ ꢁ ꢁCl
1
plied. H, 13C{1H}, 11B{1H} and 119Sn{1H} NMR spectra
were recorded at 298 K on a Varian Mercury 200 MHz
spectrometer. 11B{1H} NMR spectra was externally
referenced against BF3 Æ Et2O and 119Sn{1H} NMR spectra
against Me4Sn (d = 0 ppm). GC analysis were carried out
on a Perkin–Elmer instrument consisting of a Autosystem
XL GC. Elemental analyses were carried out by H. Kolbe,
Mikroanalytisches Laboratorium, Mulheim am Ruhr,
¨
Germany.
4.2. Synthesis of [n-BuSnCl2{C6H3(CH2NMe2)2-2,6}] (1)
A solution of n-BuSnCl3 (3.92 g, 13.5 mmol) in Et2O
(30 mL) was cooled to 0 ꢁC. Next,
a solution of
interaction shows
a
longer Sn–Cl bond distance
[LiC6H3(CH2NMe2)2-2,6]2 (2.67 g, 13.5 mmol) in Et2O
(50 mL) was added drop-wise within 1.5 h under formation
of a white precipitate. The resulting reaction mixture was
stirred for an additional 2.5 h at room temperature after
which the Et2O was evaporated in vacuo. The residue
was dissolved in toluene (50 mL) and filtered. Addition of
hexane (25 mL) to the toluene solution and storage for 4
days at ꢀ30 ꢁC resulted in the formation of colorless
needles in 67% yield. 1H NMR (CDCl3, 25 ꢁC): d 0.97
(2.5513(7)ꢁ) than the other three Sn–Cl bonds (2.4515(8),
2.4073(8) and 2.4349(8)ꢁ). The difference was smaller than
in complex 6. Except for the Cl atom involved in the
Hꢁ ꢁ ꢁCl interaction, all parameters for the ligands around
the tin center are similar. The bond distances as well as the
bond angles of the NCN-pincer moiety are in agreement
with those of closely related zwitterionic [SnBr3{C6H3-
(CH2NMe2)2-2,6}(H2O)] with intra- and intermolecular
hydrogen bonds [22].
3
3
(3H, t, JHH = 7.2 Hz, SnBu), 1.43 (2H, m, JHH = 7.4 H,
SnBu), 1.93 (2H, m, SnBu), 2.20 (2H, t, SnBu), 2.75
(12H, s, NMe3), 3.91 (4H, s, ArCH2N), 7.09 (2H, d,
3. Conclusion
3JHH = 7.6 Hz, ArH), 7.26 (t, 1H, JHH = 6.6 Hz, ArH).
3
Analysis by H and 119Sn NMR spectroscopy indicates
13C NMR (CDCl3, 25 ꢁC): d 13.7, 26.3, 28.7, 40.1, 47.6,
63.2, 126.1, 130.0, 137.3. 119Sn NMR (CDCl3, 25 ꢁC): d
ꢀ215.3. Anal. Calc. for C16H28Cl2N2Sn: C, 43.87; H,
6.44; N, 6.40. Found: C, 43.97; H, 6.40; N, 6.36%.
1
that [n-BuSnCl2(NCN)] (1) and [n-Bu3Sn(NCN)] (3) are
hexa-coordinate tin species in solution with both
CH2NMe2 donor substituents involved in N ! Sn coordi-
nation. On the other hand, [n-Bu2SnCl(NCN)] (2) is
present as a penta-coordinate species with only one of the
CH2NMe2 donor substituents coordinated to the tin
center. Reactions of 2 and 3 with SnCl4, demonstrate
that not the butyl group but the NCN pincer ligand is
4.3. Synthesis of [n-Bu2SnCl{C6H3(CH2NMe2)2-2,6}] (2)
A solution of n-Bu2SnCl2 (3.15 g, 10.0 mmol) in Et2O
(50 mL) was cooled to 0 ꢁC. Next,
a solution of

1550
S.H.L. Thoonen et al. / Journal of Organometallic Chemistry 691 (2006) 1544–1553
3
[LiC6H3(CH2NMe2)2-2,6]2 (2.08 g, 10.5 mmol) in Et2O
(50 mL) was added drop-wise within 0.5 h under formation
of a white precipitate. After the reaction mixture had stir-
red overnight at room temperature, it was filtered and
washed with Et2O (10 mL). The solvent was evaporated
in vacuo. Traces off Et2O and other volatiles were removed
in vacuo at 100 ꢁC. The resulting brown oil was dissolved
in 15 mL of CH2Cl2 and centrifuged at 2400 T/min. The
CH2Cl2 layer was carefully decantated and evaporated till
dryness. The product was isolated as a orange/brown oil
(4.13 g, 90%). 1H NMR (CDCl3, 25 ꢁC): d 0.88 (6H, t,
3JHH = 7.0 Hz, SnBu), 1.34 (8H, m, SnBu), 1.69 (4H, m,
SnBu), 2.24 (12H, s, NMe3), 3.73 (4H, s, ArCH2N), 7.05
ArH), 7.39 (8H, b, BC6H5), 7.50 (1H, t, JHH = 5.0 Hz,
ArH). 11B NMR (CDCl3, 25 ꢁC): d ꢀ6.37 (s). 13C NMR
(CDCl3, 25 ꢁC): 13.5, 14.8, 27.2, 28.3, 46.3, 64.7, 121.8,
125.6, 126.5, 128,3, 132.0, 136.4, 142.5. 119Sn NMR
(CDCl3, 25 ꢁC): d +56.5. Anal. Calc. for C48H57BN2Sn:
C, 71.08; H, 7.73; B, 1.45; N, 3.77. Found: C, 68.49; H,
7.53; B, 2.73; N, 3.26%.
Crystals were obtained by slow diffusion of hexane into
a solution of 4 in CH2Cl2.
4.6. Synthesis of [n-Bu2Sn{C6H3(CH2NMe2)2-2,6}][CF3-
SO3] (5)
3
3
(2H, d, JHH = 7.4 Hz, ArH), 7.21 (1H, t, JHH = 7.0 Hz,
ArH). 13C NMR (CDCl3, 25 ꢁC): d 13.8, 19.3, 27.4, 28.8,
45.4, 64.8, 127.5, 129.6, 140.3, 145.2 (1JCSn = 33Hz).
119Sn NMR (CDCl3, 25 ꢁC): d ꢀ44.2. Anal. Calc. for
C20H37ClN2Sn: C, 52.26; H, 8.11; Cl, 7.71; N, 6.09; Sn,
25.82. Found: C, 52.38; H, 7.99; Cl, 7.66; N, 6.09; Sn,
25.91%.
To a solution of 2 (0.5 g, 1.1 mmol) in benzene (10 mL),
silver triflate (0.28 g, 1.1 mmol) dissolved in benzene
(10 mL) was added slowly within 15 min. The reaction mix-
ture was stirred for 3 h at room temperature and was sub-
sequently filtered. The filtrate was evaporated to dryness to
give a light brown colored powder, which was re-dissolved
in dichloromethane (10 mL) and precipitated with hexane
(25 mL). The suspension was stored overnight at ꢀ30 ꢁC
after which it was filtered. The product was isolated as a
light brown powder (0.48 g, 77%). 1H NMR (CDCl3,
4.4. Synthesis of [n-Bu3Sn{C6H3(CH2NMe2)2-2,6}] (3)
3
A
solution of [LiC6H3(CH2NMe2)2-2,6]2 (2.62 g,
25 ꢁC): d 0.92 (6H, t, JHH = 7.0 Hz, SnBu), 1.43 (8H, m,
13.2 mmol) in Et2O (40 mL) was cooled to 0 ꢁC. Next, n-
Bu3SnCl (4.31 g, 13.2 mmol) dissolved in Et2O (20 mL)
was added drop-wise to the solution. The reaction mixture
was stirred for 15 h at room temperature and H2O (10 mL)
was added. The precipitate was removed by filtration and
the ether layer was washed with H2O (3 · 20 mL). The
Et2O phase was dried on MgSO4. Evaporation of the sol-
vent gave a slightly yellow oil. Yield 6.20 g (98%). 1H
NMR (CDCl3, 25 ꢁC): d 0.91 (9H, t, 3JHH = 7.2 Hz, SnBu),
SnBu), 1.77 (3H, m, SnBu), 2.58 (12H, s, NMe3), 3.83
3
(4H, s, ArCH2N), 7.21 (2H, d, JHH = 5.0 Hz, ArH), 7.42
3
(1H, t, JHH = 5.0 Hz, ArH). 13C NMR (CDCl3, 25 ꢁC):
13.5, 15.1, 27.1, 28.4, 46.7, 65.3, 126.4, 131.9, 138.5, 142.8
119Sn NMR (CDCl3, 25 ꢁC): d +60.3.
4.7. Synthesis of [n-BuSnCl2{C6H3(CH2NMe2)2-2,6}-
(HCl)] (6)
3
1.05 (6H, m, SnBu), 1.35 (6H, sextet, JHH = 7.1 Hz,
To a solution of 2 (0.5 g, 1.1 mmol) in benzene (10 mL),
0.1 M HCl (10 mL) in Et2O was added drop-wise in 15 min
to give a white precipitate. The reaction mixture was stirred
for an additional 0.5 h at room temperature after which it
was filtered and the residue was washed with cold benzene
(10 mL). The product was dried in vacuo to give 0.39 g
(72%) of a white powder. 1H NMR (CDCl3, 25 ꢁC): d
SnBu), 1.49 (6H, m, SnBu), 2.10 (12H, s, NMe3), 3.44
(4H, s, ArCH2N), 7.13 (m, 3H, ArH). 119Sn NMR (CDCl3,
25 ꢁC): d ꢀ73.9. Anal. Calc. for C24H46N2Sn: C, 59.89; H,
9.63; N, 5.82. Found: C, 59.69; H, 9.56; N, 5.71%.
4.5. Synthesis of [n-Bu2Sn{C6H3(CH2NMe2)2-2,6}]
[B(C6H5)4] (4)
3
0.98 (3H, t, JHH = 6.8 Hz, SnBu), 1.46 (2H, se,
3JHH = 7.4 Hz, SnBu), 2.05 (4H, m, SnBu), 2.61 (6H, s,
3
A solution of 2 (1.50 g, 3.3 mmol) in THF (20 mL) was
cooled to 0 ꢁC. Next, NaB(C6H5)4 (1.13 g, 3.3 mmol) dis-
solved in THF (20 mL) was added dropwise to this solution
and it was stirred for 2 h at room temperature to give a
white precipitate. The reaction mixture was centrifuged
and the THF phase was carefully decanted and evaporated
to dryness. The residue was dissolved in CH2Cl2 and the
product was precipitated upon addition of hexane to the
solution at ꢀ30 ꢁC. The product was isolated by filtration,
washed with hexane (2 · 10 mL) and dried in vacuo to give
NCH3), 2.85 (6H, d, JHH = 4.4 Hz, N+CH3), 3.98 (2H,
b, CH2N), 4.78 (2H, br, CH2N+), 7.21 (3H, m, ArH),
10.91 (1H, b, N+H). 13C NMR (CDCl3, 25 ꢁC): 14.2,
26.1, 29.0, 44.1, 42.6, 46.5, 62.1, 64.2, 129.1, 134.0, 134.5
140.8. 119Sn NMR (CDCl3, 25 ꢁC): d ꢀ304.0. Anal. Calc.
for C12H20Cl4N2Sn: C, 40.50; H, 6.16; N, 5.99. Found:
C, 39.88; H, 6.03; N, 5.63%.
4.8. Reaction of 1 with SnCl4
1
1.95 g (79%) of a white powder. H NMR (CDCl3, 25 ꢁC):
To a solution of 1 (0.70 g, 1.60 mmol) in hexane
(30 mL), SnCl4 (0.19 mL, 1.60 mmol) was added. The
reaction mixture was stirred for 16 h at room temperature
during which a white precipitate was formed. Next, the pre-
cipitate was isolated by filtration, dissolved in CH2Cl2
3
d 0.97 (6H, t, JHH = 5.0 Hz, SnBu), 1.45 (8H, m, SnBu),
1.61 (3H, m, SnBu), 2.51 (12H, s, NMe3), 3.72 (4H, s,
3
ArCH2N), 6.91 (t, 4H, JHH = 4.8 Hz, BC6H5), 7.06 (8H,
3
3
t, JHH = 4.8 Hz, BC6H5), 7.25 (2H, d, JHH = 5.0 Hz,

S.H.L. Thoonen et al. / Journal of Organometallic Chemistry 691 (2006) 1544–1553
1551
ꢀ1
˚
(10 mL) and the solution was filtered again. The product
was precipitated with pentane (10 mL), isolated by filtra-
tion and dried in vacuo to give 0.74 g (66%) of a white pow-
(sinh/k)max = 0.65 A at a temperature of 150(2) K. The
structures were solved with automated Patterson methods
[26] and refined with SHELXL-97 [27] on F2 of all reflections.
Geometry calculations, drawings and checking for higher
symmetry were performed with the PLATON package [28].
1
der. H, 13C and 119Sn NMR data of the product were
identical to those of 6.
4.9. Reaction of 2 with SnCl4
5.1. Compound 1
To a solution of 2 (0.75 g, 1.63 mmol) in toluene
(10 mL), SnCl4 (0.19 mL, 1.63 mmol) was added. The reac-
tion mixture was stirred for 1 h at room temperature dur-
ing which a slightly yellow oil was formed. Next, the
upper toluene layer was decanted and all volatiles were
removed in vacuo to give 0.20 g of a white solid which
was found to be a mixture of n-Bu2SnCl2 (84%) and 8
(16%) (1H NMR). The yellow oil (1.00 g) was characterized
by 1H NMR as a mixture of n-Bu2SnCl2 (41%) and 8
C16H28Cl2N2Sn, formula weight = 437.99, colorless nee-
dle, 0.61 · 0.20 · 0.09 mm3, orthorhombic, Pbca (no. 61),
˚
˚
˚
a = 10.2522(2) A, b = 12.3622(2) A, c = 30.3866(5) A,
V = 3851.19(12) A , Z = 8, Dcalc = 1.511 g/cm3. 54404
3
˚
reflections were measured. An absorption correction based
on multiple measured reflections was applied (l =
1.601 mmꢀ1, 0.72–0.86 correction range). 4405 reflections
were unique (Rint = 0.048). Non-hydrogen atoms were
refined with anisotropic displacement parameters. All
hydrogen atoms were located in the difference Fourier
map and refined freely with isotropic displacement
parameters. The methyl group at C20 was disordered over
two positions. 302 parameters were refined with no
restraints. R1/wR2 [I > 2r(I)]: 0.0179/0.0443. R1/wR2 [all
reflections]: 0.0226/0.0462. S = 1.065. Residual electron
1
(59%). H NMR (CDCl3, 25 ꢁC): d 2.84 (6H, s, NCH3),
3
2.94 (6H, d, JHH = 4.8 Hz, N+CH3), 4.09 (2H, s,
CH2N), 5.01 (2H, br, CH2N+), 7.27 (3H, m, ArH), 9.78
(1H, b, N+H); 119Sn NMR (CDCl3, 25 ꢁC): d ꢀ258.0 (8).
1
The H NMR data of n-Bu2SnCl2 were in good agreement
with the literature values [24].
3
˚
The same reaction was also performed in NMR tube
density between ꢀ0.42 and 0.38 e/A .
1
with CDCl3 as solvent and monitored by H and 119Sn
NMR spectroscopy. To
a
solution of
2
(30 mg,
5.2. Compound 4
0.065 mmol) in CDCl3 (0.5 mL), SnCl4 (7.5 lL,
0.065 mmol) was added. After 10 min at room tempera-
ture, NMR spectra displayed the formation of equimolar
amounts 7 and n-Bu2SnCl2 and traces of 8 (<5%). 1H
NMR (CDCl3, 25 ꢁC): d 2.83 (12H, s, NCH3), 4.17 (4H,
[C20H37N2Sn][C24H20B] Æ CH2Cl2, formula weight =
828.34, colorless block, 0.39 · 0.27 · 0.27 mm3, mono-
˚
˚
clinic, P21/c (no. 14), a = 14.6597(1) A, b = 16.6642(2) A,
3
˚
˚
c = 22.4244(1) A, b = 128.2072(5)ꢁ, V = 4304.58(7) A ,
Z = 4, Dcalc = 1.278 g/cm3. 79503 reflections were mea-
sured. An absorption correction based on multiple mea-
sured reflections was applied (l = 0.750 mmꢀ1, 0.72–0.81
3
s, CH2N), 7.47 (2H, d, JHH = 7.2 Hz, ArH), 7.36 (1H, t,
3JHH = 7.8 Hz, ArH); 119Sn NMR (CDCl3, 25 ꢁC): d
ꢀ295.3 (7). The 1H NMR data of n-Bu2SnCl2 were in good
agreement with the literature values [24].
correction range). 9865 reflections were unique (Rint
=
0.054). Non-hydrogen atoms were refined with anisotropic
displacement parameters. Hydrogen atoms were intro-
duced in geometrically idealized positions and refined with
a riding model. 487 parameters were refined with 45
restraints. R1/wR2 [I > 2r(I)]: 0.0303/0.0697. R1/wR2 [all
reflections]: 0.0425/0.0744. S = 1.034. Residual electron
4.10. Reaction of 3 with SnCl4
To a solution of 3 (1.06 g, 2.20 mmol) in pentane
(20 mL), SnCl4 (0.25 mL, 2.20 mmol) dissolved in pentane
(20 mL) was added. The reaction mixture was stirred for
16 h at room temperature during which a white precipitate
was formed. The product was isolated by filtration, washed
with pentane (5 mL) and dried in vacuo. Yield: 0.91 g of a
3
˚
density between ꢀ0.50 and 0.65 e/A .
5.3. Compound 6
1
white powder. The H and 119Sn NMR spectra displayed
the presence of 8 and n-Bu3SnCl (11%). All volatiles were
C16H29Cl3N2Sn, formula weight = 474.45, colorless
removed in vacuo to afford 0.62 g of a colorless oil
block, 0.36 · 0.27 · 0.24 mm3, monoclinic, P21 (no. 4),
1
˚
˚
˚
(87%). The oil was identified by H NMR spectroscopy
a = 10.4185(1) A, b = 13.2394(2) A, c = 29.5834(4) A, b =
3
˚
as n-Bu3SnCl [25]. Single crystals of 8 were obtained by
storing a concentrated CH2Cl2 solution of 8 for one week
at ꢀ25 ꢁC.
89.9920(5)ꢁ, V = 4080.58(9) A , Z = 8, Dcalc = 1.545
g/cm3. 83300 reflections were measured. An absorption
correction based on multiple measured reflections was
applied (l = 1.644 mmꢀ1, 0.63–0.68 correction range).
18317 reflections were unique (Rint = 0.042). The crystal
appeared to be pseudo-merohedrally twinned with a two-
fold rotation about the reciprocal a* axis as twin operation
(pseudo-orthorhombic twinning). The twin fraction refined
to 0.5070(4). Non-hydrogen atoms were refined with aniso-
5. X-ray crystal structure determinations
X-ray intensities were measured on a Nonius Kappa
CCD diffractometer with rotating anode and graphite
˚
monochromator (k = 0.71073 A) up to a resolution of

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S.H.L. Thoonen et al. / Journal of Organometallic Chemistry 691 (2006) 1544–1553
´
´
(b) C. Mateo, D. Cardenas, C. Fernandez-Rivas, A.M. Echavarren,
tropic displacement parameters. All hydrogen atoms were
located in the difference Fourier map. The NH hydrogen
atoms were refined freely with isotropic displacement
parameters; all other hydrogen atoms were refined with a
riding model. 830 parameters were refined with one
restraint. R1/wR2 [I > 2r(I)]: 0.0217/0.0482. R1/wR2 [all
reflections]: 0.0229/0.0487. S = 1.028. Flack parameter
x = ꢀ0.028(8). Residual electron density between ꢀ0.60
Chem. Eur. J. 12 (1996) 1596;
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3
˚
and 0.50 e/A .
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¨
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5.4. Compound 8
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(e) M. Herberhold, T. Schmalz, W. Milius, B. Wrackmeyer, J.
Organomet. Chem. 641 (2002) 173.
C12H20Cl4N2Sn, formula weight = 452.79, colorless nee-
dle, 0.30 · 0.06 · 0.06 mm3, tetragonal, I41/a (no. 88),
3
˚
˚
˚
a = b=27.3794(3) A, c = 19.4629(2) A, V = 14590.0(3) A ,
Z = 32, Dcalc = 1.649 g/cm3. 91185 reflections were mea-
sured. An analytical absorption correction was applied
(l = 1.977 mmꢀ1, 0.77–0.96 correction range). 8377 reflec-
tions were unique (Rint = 0.061). Non-hydrogen atoms were
refined with anisotropic displacement parameters. Hydro-
gen atoms were introduced in geometrically idealized
positions and refined with a riding model. The crystal
[5] (a) J.T.B.H. Jastrzebski, C.T. Knaap, G. van Koten, J. Organomet.
Chem. 255 (1983) 287;
(b) J.T.B.H. Jastrzebski, J. Boersma, P.M. Esch, G. van Koten,
Organometallics 10 (1991) 930;
(c) P. Steenwinkel, J.T.B.H. Jastrzebski, B.J. Deelman, D.M. Grove,
H. Kooijman, N. Veldman, W.J.J. Smeets, A.L. Spek, G. van Koten,
Organometallics 16 (1997) 5486;
(d) E. Vedesj, A.R. Haight, W.O. Moss, J. Am. Chem. Soc. 114
(1992) 6556.
3
˚
structure contains large voids (1086.4 A /unit cell) filled
with disordered solvent molecules. Their contribution to
the structure factors was secured by back-Fourier transfor-
mation using the SQUEEZE routine of the PLATON
program [28] resulting in 334 electrons/unit cell. 343
parameters were refined with no restraints. R1/wR2
[I > 2r(I)]: 0.0305/0.0579. R1/wR2 [all reflections]: 0.0503/
0.0618. S = 1.009. Residual electron density between
[6] J.T.B.H. Jastrzebski, G. van Koten, Adv. Organomet. Chem. 35
(1993) 241.
[7] (a) For structurally related Sn complexes based on NCN and other
pincer-type ligands see: A. Ruzicka, R. Jambor, J. Brus, I. Cisarova,
J. Holecek, J. Inorg. Chim. Acta 323 (2001) 163;
(b) R. Jambor, L. Dostal, A. Ruzicka, I. Cisarova, J. Brus, M.
Holcapek, J. Holecek, Organometallics 21 (2002) 3996;
(c) P. Novak, I. Cisarova, R. Jambor, A. Ruzicka, J. Holecek, Appl.
Organomet. Chem. 18 (2004) 241;
(d) B. Kasna, R. Jambor, L. Dostal, A. Ruzicka, I. Cisarova, J.
Holecek, Organometallics 23 (2004) 5300;
(e) K. Peveling, M. Henn, C. Loew, C. Mehring, M. Schuermann, B.
Costisella, K. Jurkschat, Organometallics 23 (2004) 1501.
[8] (a) D.M. Grove, A.H.M. Verschuuren, G. van Koten, J.A.H. van
Beek, J. Organomet. Chem. 372 (1989) C1;
3
˚
ꢀ0.43 and 0.41 e/A .
6. Supplementary data
CCDC-287817 (compound 1), -287818 (4), -287819 (6),
and -287820 (8) contain the supplementary crystallographic
data for this paper. These data can be obtained free of
charge from The Cambridge Crystallographic Data Centre
via www.ccdc.cam.ac.uk/data_request/cif.
(b) G. van Koten, Pure Appl. Chem. 61 (1989) 1681;
(c) C. Granel, P. Dubois, R. Je´roˆme, P. Teyssie´, Macromolecules 29
(1996) 8576;
(d) L.A. van der Kuil, D.M. Grove, R.A. Gossage, J.W. Zwikker,
L.W. Jenneskens, W. Drenth, G. van Koten, Organometallics 16
(1997) 4985;
Acknowledgements
(e) H.P. Dijkstra, M.D. Meijer, J. Patel, R. Kreiter, G.P.M. van
Klink, M. Lutz, A.L. Spek, A.J. Canty, G. van Koten, Organomet-
allics 20 (2001) 3159;
(f) A.W. Kleij, R.J.M. Klein Gebbink, P.A.J. van den Nieuwehuijzen,
H. Kooijman, M. Lutz, A.L. Spek, G. van Koten, Organometallics
20 (2001) 634.
This work was supported by Arkema Vlissingen B.V.
(previously Atofina Vlissingen), the Dutch Ministry for
Economic Affairs/SENTER and the Council for Chemical
Sciences of The Netherlands Organization for Scientific
Research (CW-NWO).
[9] M. Albrecht, M. Lutz, A.L. Spek, G. van Koten, Nature 20 (2001)
634.
[10] P. Steenwinkel, D.M. Grove, N. Veldman, A.L. Spek, G. van Koten,
Organometallics 17 (1998) 5647.
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