Synthesis and structures of β-diketiminatotin(II) halides, an amide and of Sn(=E)[{N(R)C(Ph)}2CH](NR2) (E = S or Se, R = SiMe3)

Article abstract of DOI:10.1039/b412765j

Treatment of [Li(L¹)]₂ (1) or K(L²) (2) with SnX₂ in Et₂O yielded the heteroleptic β-diketiminatotin(II) halides Sn(L¹)Cl (3a), Sn(L¹)Br (3b) or Sn(L²)Cl (4), even when an excess of the alkali metal β-diketiminate was used [L¹ = {N(R)C(Ph)}₂CH, L ² = {N(R)C(Ph)CHC(Bu¹)N(R)}, R = SiMe₃]. From 2 and half an equivalent each of SnCl₂·2H₂O and SnCl₂, or one equivalent of SnCl₂·2H₂O, the product was Sn(L₃)Cl (5) or Sn(L⁴)Cl (6), in which one or both of the N-R bonds of L¹ had been hydrolytically cleaved; the compound Sn(L⁵)Cl (7) was similarly obtained from 1 and an equivalent portion of SnCl₂·2H₂O [L³ = {N(R)C(Ph)CHC(Bu¹)N(H)}, L⁴ = {N(H)C(Ph)CHC-(Bu ¹)N(H)} and L³ = {N(H)C(Ph)}₂CH]. The halide exchange between 3a and 3b, studied by two-dimensional ¹¹⁹Sn{ ¹H}-NMR spectroscopy, is attributed to implicate a (μ-Cl)μ-Br)-dimeric intermediate or transition state. The ¹³C{¹H}-NMR spectra of 3a or 3b showed two distinct resonances for each group, which coalesced on heating, corresponding to ?G_{338 K} = 69.4 (3a) or 72.8 (3b) kJ mol^-1. The chloride ligand of 3a was readily displaced by treatment with NaNR₂, CF₃SO₃H or CH₂(COPh)₂, yielding Sn(L¹)X (X = NR₂ (8), O₁SCF₃ (9) or {OC(Ph)}₂CH (10)]. Oxidative addition of sulfur or selenium to 8 gave the tin(IV) terminal chalcogenidcs Sn(E)(L¹)(NR₂) [E = S (11) or Se (12)]. The X-ray structures of the cocrystal of 3a/3b and of the crystalline compounds 5, 6, 8, and 11 are presented, as well as multinuclear NMR spectra of each of the new compounds.

Full text of DOI:10.1039/b412765j

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F U L L P A P E R
Synthesis and structures of b-diketiminatotin(II) halides, an amide
=
and of Sn( E)[{N(R)C(Ph)}2CH](NR2) (E = S or Se, R = SiMe3)
Peter B. Hitchcock, Jin Hu, Michael F. Lappert* and John R. Severn
The Chemistry Laboratory, University of Sussex, Brighton, UK BN1 9QJ.
E-mail: m.f.lappert@sussex.ac.uk
Received 18th August 2004, Accepted 20th October 2004
First published as an Advance Article on the web 16th November 2004
Treatment of [Li(L1)]2 (1) or K(L2) (2) with SnX2 in Et2O yielded the heteroleptic b-diketiminatotin(II) halides
Sn(L1)Cl (3a), Sn(L1)Br (3b) or Sn(L2)Cl (4), even when an excess of the alkali metal b-diketiminate was used [L1 =
{N(R)C(Ph)}2CH, L2 = {N(R)C(Ph)CHC(But)N(R)}, R = SiMe3]. From 2 and half an equivalent each of
SnCl2·2H2O and SnCl2, or one equivalent of SnCl2·2H2O, the product was Sn(L3)Cl (5) or Sn(L4)Cl (6), in which one
or both of the N–R bonds of L1 had been hydrolytically cleaved; the compound Sn(L5)Cl (7) was similarly obtained
from 1 and an equivalent portion of SnCl2·2H2O [L3 = {N(R)C(Ph)CHC(But)N(H)}, L4 = {N(H)C(Ph)CHC-
(But)N(H)} and L5 = {N(H)C(Ph)}2CH]. The halide exchange between 3a and 3b, studied by two-dimensional
1
119Sn{ H}-NMR spectroscopy, is attributed to implicate a (l-Cl)(l-Br)-dimeric intermediate or transition state. The
1
13C{ H}-NMR spectra of 3a or 3b showed two distinct resonances for each group, which coalesced on heating,
corresponding to DG338 K = 69.4 (3a) or 72.8 (3b) kJ mol−1. The chloride ligand of 3a was readily displaced by
treatment with NaNR2, CF3SO3H or CH2(COPh)2, yielding Sn(L1)X [X = NR2 (8), O3SCF3 (9) or {OC(Ph)}2CH
(10)]. Oxidative addition of sulfur or selenium to 8 gave the tin(IV) terminal chalcogenides Sn(E)(L1)(NR2) [E = S
(11) or Se (12)]. The X-ray structures of the cocrystal of 3a/3b and of the crystalline compounds 5, 6, 8, and 11 are
presented, as well as multinuclear NMR spectra of each of the new compounds.
CHR2; or SnAr[Si{(NCH2But)2C6H4-1,2}]Y with Y = NR2
6d
Introduction
6e
or Ar = C6H3(NMe2)2-2,6 ], Z[N(R)Sn(X)]2 (Z = C6H4-1,4
This study derives from an interaction of two diverse topics,
each of which has a long-standing history in our group. On the
one hand it concerns b-diketiminatometal complexes and on
the other it deals with low molecular weight lipophilic tin(II)
compounds.
or C6H10-1,4 and X = NR2 or OC6H2But2-2,6-Me-4 ), Sn-
6f
t
6g
6h
(NR2)(OC6H2Bu 2-2,6-Me-4),
[{Sn(NR2)(l-O3SCF3)}2]∞,
5h
6i
Sn{N(R)C(Ph)CR2}X [X = Cl, or N(R)C(Ph)=CR2 ],
5l
and Sn{CR2(C5H4N-2)}X (I) (X = Cl or NR2); among
6j
those made elsewhere are [Sn(l-H)Ar]2, Sn(Ar)X [Ar =
b-Diketiminates are increasingly important spectator ligands
by virtue of their diversity of bonding modes. The b-diketiminato
ligands are able to stabilise compounds not only in an unusually
low state of molecular aggregation but also in a low metal
oxidation state, as cations, and others containing metal multiply
bonded coligands; and many b-diketiminatometal complexes
have a useful role as catalysts or biomolecular mimics. The
topic has been reviewed.1 Our studies in this area date back
to 1994 with the synthesis and some reactions of crystalline
i
ꢀ
ꢀ
ꢀ
6k
6l
6k
5k
C6H3(C6H2Pr 3-2 ,4 ,6 )2-2,6 and X = I, Cl, NR2, , SnArPh,
5
t
6l, 6m
6l
6l, 6m
6m
Cr(g -C5H5)(CO)3, Bu ,
SnCl{C6H3(CH2NMe2)2-2,6},
SnArMe2,
Sn(Me)Li(Ar), ],
6o
6p
Sn(Cl){C(SiMe2Ph)3},
Sn-
Sn(Cl)-
5m
{C(H)R(C9H6N-8)}X (X
=
F, Cl, Br or I),
i
i
6q
{N(Pr )C7H5N(Pr )},
and Sn(X){N(Prn)C7H5N(Prn)} (II)
6r
(X = Cl or N3).
[Li(L1)]2 (1) and KL2 (2) [L1 = {N(R)C(Ph)}2CH, L2
=
2a
2b
{N(R)C(Ph)CHC(But)N(R)}, R = SiMe3] and our most recent
publications are to be found in ref. 3.
Our researches in tin(II) chemistry began in 1973 with the dis-
4a
closure of the red [Sn(CHR2)2]n (n = 1 in a dilute hydrocarbon
solution or in the gas phase, or n = 2 for the Sn–Sn bonded
This paper deals with heteroleptic b-diketiminatotin(II) com-
pounds Sn(L)X (3–10) and two of their tin(IV) adducts (11 and
12), in which L is a b-diketiminato ligand of general formula III
[specifically L1 (R1 = R = R2, R3 = Ph =R4), L2 (R1 = R =
R2, R3 = Ph, R4 = But), L3 (R1 = R, R2 = H, R3 = Ph, R4 =
But), L4 = (R1 = H = R2, R3 = Ph, R4 = But), or L5 (R1 =
H = R2, R3 = Ph =R4)] and X = Cl, Br, NR2, O3SCF3, or
{OC(Ph)}2CH. Some of the data have been briefly outlined in
our comprehensive review1 and for Sn(L1)Br (3b), Sn(L3)Cl (7)
and Sn(L4)Cl (6) in an earlier (1996) survey,7 but are described
herein in detail. Related compounds of formula IV [in which the
b-diketiminato ligand is L6 (R1 = Ph = R2, R3 = Me = R4), L7
(R1 = C6H3Pri2-2,6 = R2, R3 = Me = R4) or L8 (R1 = C6H2Me3-
2,4,6 = R2, R3 = Me = R4) have featured in Sn(L6)X (X = Cl,
crystalline dimer). Other homoleptic, monomeric crystalline
SnX2 complexes made at Sussex were with X = NR2, 1 [N(Me)2-
5a
2
1
2
5d
t
t
5a
5b
5c
(CH2)3CMe2] (≡ TMP), OC6H2Bu 2-2,6-Me-4, OCBu 3,
SC6H2Bu 3-2,4,6, [{N(CH2Bu )}2C6H4-1,2], 12 [N(R)C(Ph)-
t
t
5e
t
5f
5g
NC(Ph)=CR2],
Si(NR2)[{N(CH2Bu )}2C6H4-1,2],
and
1
t
5h
2 [N(R)C(Bu )CHR]; among those made elsewhere are those
i
5i
5j
5k
with X = Sn{C6H3(OPr )2-2,6}3, C6H3Mes2-2,6, SnArPh2
[Ar = C6H3{C6H2Pr 3-2 ,4 ,6 }2-2,6], CR2(C5H4N-2), C(R)Ph-
(C5H4N-2), and C(H)R(C9H6N-8), Sn[N(Pr )C7H5N(Pr )]2,
i
ꢀ
ꢀ
ꢀ
5l
i
i
5m
5n
5o
i
5p
5p
N(R)C6H3Pr 2-2,6, and N(SiMe2Ph)2.
Of direct relevance in the present context are low molecular
weight, lipophilic, heteroleptic tin(II) compounds [Sn(X)Y]n
(n = 1 or 2). Our prior publications in this area relate to the
crystalline complexes trans-[Sn(l-Cl)NR2]2,
cis-[Sn(l-Cl)
I, NR2, O3SCF3 or N3),8 Sn(L7)X [X = OPri,9,10 Cl,9,10 But,10
6a
i
(TMP)]2,
cis-[Sn(l-Br)(TMP)]2,
trans-[Sn(l-F)(TMP)]2,
Sn(NCS)(NR2), Sn{C6H3(NMe2)2-2,6}X [X = Cl, NR2, or
O3SCF3,10 or N(Ar)C(Me) C(H)C(Me) NAr (Ar = C6H3Pr 2-
6a
6a
6b
=
=
2,6) (V),10 and Sn(L8)X (X = Cl or N3).11
6c
T h i s j o u r n a l i s
T h e R o y a l S o c i e t y o f C h e m i s t r y 2 0 0 4
D a l t o n T r a n s . , 2 0 0 4 , 4 1 9 3 – 4 2 0 1
4 1 9 3
©

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The reaction of SnCl2 with one equivalent of [LiL1]2 (1) in
diethyl ether yielded the (b-diketiminato)tin(II) halide 3. The
reaction was complicated by the unexpected incorporation of
bromine. The bromine is believed to have come from LiBr, which
is present in unsublimed LiCH(SiMe3)2. The complex was a
mixed halide cocrystal [Sn(L1)X] (X = Cl/Br). When sublimed
LiCH(SiMe3)2 was used for the initial ligand synthesis, a clean
reaction with SnCl2 and SnBr2 was observed affording the (b-
diketiminato)tin(II) halides 3a (Cl) and 3b (Br).
Results and discussion
An attempt was made to prepare both Sn(L2)2 and Sn(L2)Cl
(4) from SnCl2 and K(L2) in appropriate stoichiometry. An-
hydrous SnCl2 in thf was treated with an equivalent portion
of K(L2) at 0 ◦C. After filtration, removal of volatiles, and
concentration and cooling of the hexane extract of the residue,
the pale yellow crystalline Sn(L2)Cl (4) was obtained. Likewise,
from excess of K(L2) and SnCl2, only 4 was obtained. Evidently
Sn(L2)2 is too sterically hindered to be readily accessible. A
similar conclusion was made about Sn(L7)2; attempted reduction
of Sn(L7)Cl with KC8 yielded V, an isomer of Sn(L7)2.10
The first b-diketiminatotin complexes, the crystalline SnIV(L1)-
(Cl)Me2 and SnIV(L5)(Cl)Me2, were described in 1994.2 They
were prepared according to eqn. (1).
(1)
When a long-stored sample of SnCl2 was used in the
SnCl2/K(L2) reaction, a small amount of the mono-desilyated
compound Sn(L3)Cl (5) was isolated in addition to 4. This is
attributed to the partial hydrolysis of 4 by water absorbed in
the SnCl2 sample. Next we turned to employing a stoichiometric
quantity of water in efforts to effect mono-or-bis-desilylation,
by using a 1 : 1 ratio of SnCl2 to SnCl2·2H2O or only the latter,
respectively. When the reaction was carried out in thf at 0 ◦C, a
mixture of products resulted. However, the following strategy
was successful: cooling the tin(II) chloride mixture in thf at
−78 ◦C, adding K(L2) at this temperature until the all the solids
had dissolved, and then warming to ambient temperature. In this
fashion, high yields of the pale yellow, crystalline compounds
Sn(L3)Cl (5) and Sn(L4)Cl (6) were obtained. Using the same
technique, the pale yellow, crystalline compound Sn(L7)Cl (7)
was prepared in high yield. It may be that when carrying out
the reaction at 0 ◦C, the hydrolysis of K(L2) to give HL2 was a
significant competing reaction to the ligand transfer of L2 from
K to Sn. It is noted that the ionic compound [Li(L1)]2 was readily
hydrolysed by moist air to give HL1, whereas the more covalent
Sn(L1)(Cl)Me2 was desilyated, eqn. (1).2 The low temperature
hydrolysis of Sn(L2)Cl (4) is evidently highly regiospecific. That
nucleophilic attack by H2O at a Si atom was preferred over that at
the Sn atom is attributed to the greater oxophilicity of the former.
The preference of attack at the silicon atom of C(But)N(SiMe3)
rather than C(Ph)N(SiMe3) may be due to a steric acceleration
factor; thus, for the former the hydrolysis offers greater relief of
steric strain, that between adjacent But and SiMe3 groups being
greater than that between Ph and SiMe3.
The nature of the SnNCCCN metallacycle in the two com-
pounds differed: being almost planar in the latter, but boat-
shaped in the former with the tin atom 0.76 A out of the
˚
NC–CN plane. Thus, the chelating ligand may be regarded as
bonding to the metal in a four-electron r-bonding j2-fashion
5
in Sn(L5)(Cl)Me2 but a six-electron 2r + 4p g -fashion in
Sn(L1)(Cl)Me2. The facile conversion of Sn(L1)(Cl)Me2 into
Sn(L5)(Cl)Me2 demonstrated not only the steric significance of
the trimethylsilyl (≡R) substituents but also their potential as
readily removable protecting groups.
At the outset of the present investigation,7 b-diketi-
minatotin(II) complexes were unknown. Hence the objectives
in this research were (i) to synthesise and characterise such
compounds; (ii) to determine whether L2Sn(II) complexes were
readily and regiospecifically hydrolysable by replacing one N(R)
[proximal to CBut or CPh] or both N–R groups of L2 by N–H;
(iii) to investigate the steric influence exercised not only by the L1
ligand, but also the wider range L1 to L5; (iv) to determine the
structure and bonding for the series of Sn(L)X compounds (L =
L1 to L5); and (v) to study the reactivity of Sn(L)X compounds
with respect both to nucleophilic displacement of X− and to
oxidative addition.
Synthesis and characterisation of the b-diketiminatotin(II)
halides 3, 3a, 3b and 4–7
The syntheses of the b-diketiminatotin(II) halides Sn(L1)Cl/Br
(3), Sn(L1)Cl (3a), Sn(L1)Br (3b), Sn(L2)Cl (4), Sn(L5)Cl (5),
Sn(L4)Cl (6) and Sn(L5)Cl (7) are summarised in Scheme 1.
Each of the b-diketiminatotin(II) halides 3a, 3b, 4, 5, 6
1
and 7 gave satisfactory microanalytical results and H-NMR
spectra in C6D6 or (for 7) C6D6/C4D8O at 298 K, and
showed the monomeric parent ion in the EI-mass spec-
trum. Additionally, X-ray diffraction studies on each of the
crystalline compounds 3–6 revealed them to be monomeric,
three-coordinate, pyramidal tin(II) chlorides, having a stere-
ochemically active lone pair of electrons at the Sn atom.
The 119Sn{ H}-NMR spectral chemical shifts for the series
1
of complexes Sn[N(R1)C(But)C(H)C(Ph)N(R2)]Cl decreased
monotonically in frequency as the substituents R1/R2 were
sequentially changed from SiMe3 to H: d −118.0 (4), d −166.5
(5) and d −219.9 (6); the same pattern was revealed for
Sn[{N(R1)C(Ph)}2CH]Cl, with d −118.2 (R1 = SiMe3, 3a) and d
−189.9 (R1 = H, 6). [However, for Sn[{N(R)C(Ph)}2CH]Cl the
119Sn chemical shifts were essentially identical for R1 = SiMe3 (d
184.2) and R1 = H (d 184.6).2]. For the series 4–6, the trend in the
1H-NMR chemical shift for the endocyclic CH group followed
the pattern: d 6.00 (4), d 5.45 (5) and d 5.31 (6). It may be that
these trends are attributable to the p-electron-withdrawing affect
of the SiMe3 groups at the nitrogen atoms. Compound 4 showed
distinct and separate SiMe3 1H-NMR chemical shift signals,
Scheme 1 Synthesis of b-diketiminatotin(II) halides (R = SiMe3).
4 1 9 4
D a l t o n T r a n s . , 2 0 0 4 , 4 1 9 3 – 4 2 0 1

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for Sn(L)Cl [L = {N(Ph)C(Me)}2CH (≡L6),8 {N(C6H3Pri2-
2,6)C(Me)}2CH (≡L7),10 or {N(C6H2Me3-2,4,6)C(Me)}2CH
(≡L8)11]; data for 4 are closely similar to those for 3a. The halide
ligand in 3 is an unresolved mixture of Br and Cl in a ratio
that refines to 0.6 : 0.4; any dimension involving the halide is
unreliable. Each of the compounds 5 and 6 crystallised with two
independent molecules in the unit cell, with essentially the same
geometry; hence data only for one are shown in Figs. 2 and 3
and Table 1.
consistent with the X-ray structure, having one SiMe3 proximal
to But and the other to Ph. The mono-desilylated compound
5 showed only a single SiMe3 signal, in accord with its X-ray
structure as a pure compound and not a mixture of 5 and an
isomer with the H and SiMe3 substituents attached to the two
nitrogen atoms being exchanged.
Crystal structures of compounds 3, 5 and 6
The molecular structures of crystalline Sn(L1)Cl/Br (3),
Sn(L3)Cl (5) and Sn(L4)Cl (6) are illustrated in Figs. 1–3, respec-
tively; selected geometric data are in Table 1, together with those
As noted above, the effect of changing NSiMe3 substituents
for NH in Sn[{N(R1)C(Ph)}2CH](Cl)Me2 on the nature of the
NCCCNSn ring, was profound, being ‘boat’-shaped for R1 =
SiMe3 but planar for R1 = H;2 this is not so pronounced for
the present tin(II) halides. Nevertheless, there is a significant
conformational trend as a function of sequentially changing
from compound 3 with both nitrogen atoms of the NCCCNSn
ring having an SiMe3 substituent, through 5 which has one
NSiMe3 and one NH group, to compound 6 having hydrogen
atoms on both nitrogen atoms. Thus the central carbon atom
and the tin atom of the ring in each of the 3, 5 and 6
molecules is above the essentially coplanar NC–CN moiety, with
increasing tendency to change from near ring coplanarity in 6
to pronounced boat conformation in 3. This is illustrated by the
data in Table 2, which includes similar geometric parameters
1
1
=
for compounds Sn(L )NR2 (8) and Sn(L )NR2( S) (11) which,
however, are closer to having a coplanar b-diketiminatotin ring
even than 6.
Fig. 1 Molecular structure of 3; the atom marked “Br” is an unresolved
mixture of Br and Cl (see text); hydrogen atoms are omitted for clarity.
Thermal ellipsoids are shown at the 50% probability level.
Halide exchange in the b-diketiminatotin(II) halides 3a and 3b
1
The 119Sn{ H}-NMR spectra in PhMe/C6D6 at 298 K of com-
plex 3, or a mixture of complexes 3a and 3b, showed two signals
at d −118.2 and −64.5 assigned to Sn(L1)Cl (3a) and Sn(L1)Br
(3b), respectively, which in the case of complex 3 integrated in
1
a ratio of 4 : 6. The 2D EXSY 119Sn{ H}-NMR spectra were
recorded in the phase-sensitive mode with time-proportional
phase incrementation12 using the basic pulse sequence of Jeener13
with proton-decoupling only during the pulse sequence and
signal acquisition. A standard 16-dimensional phase cycle, as
set up in the Bruker microprogram library, was used. The total
experiment time was 12 h, with 200 ms mixing times. The cross
peak X (Fig. 4) indicates that the two tin species were exchanging
on the NMR time scale. This is believed to have proceeded via
an intermolecular process with an intermediate or transition
state, shown in VII involving a dimer bridged by chloride
and bromide. This is consistent with other tin–halide exchange
Fig. 2 Molecular structure of 5; hydrogen atoms are omitted for clarity.
Thermal ellipsoids are shown at the 50% probability level.
processes studied via 2D EXSY 119Sn-NMR spectra.14 The
1
13C{ H}-NMR spectrum of complex 3, or a mixture of 3a and
3b, in benzene at 298 K showed two distinct resonances for each
group. These coalesced at 338 K, the coalescence temperature
Tc, corresponding to a DG= = 69.4 and 72.8 kJ mol−1 for 3a
T c
Fig. 3 Molecular structure of 6; hydrogen atoms are omitted for clarity.
Thermal ellipsoids are shown at the 50% probability level.
and 3b, respectively in a system of ratio 4 : 6.15
D a l t o n T r a n s . , 2 0 0 4 , 4 1 9 3 – 4 2 0 1
4 1 9 5

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◦
˚
Table 1 Selected bond lengths (A) and angles ( ) for b-diketiminatotin(II) halides
Bond
3a
5
6
Sn(L6)Cl8
Sn(L7)Cl10
Sn(L8)Cl11
Sn–N(1)
Sn–N(2)
Sn–Cl
N(1)–C(1)
N(2)–C(3)
C(1)–C(2)
C(2)–C(3)
2.174(3)
2.172(3)
2.546(1)a
1.334(4)
1.333(4)
1.391(5)
1.389(5)
2.163(6)
2.129(6)
2.502(3)
1.351(9)
1.309(9)
1.371(10)
1.408(10)
2.142(9)
2.129(9)
2.554(3)
1.312(14)
1.344(14)
1.384(15)
1.372(16)
2.170(9)
2.174(9)
2.500(3)
1.379(15)
1.338(14)
1.349(17)
1.453(17)
2.185(2)
2.180(2)
2.473(9)
1.329(3)
1.343(3)
1.402(4)
1.393(4)
2.162(3)
2.162(3)
2.468(1)
1.330(5)
1.330(5)
1.392(4)
1.392(4)
N(1)–Sn–N(2)
N(1)–Sn–Cl
N(2)–Sn–Cl
C(1)–N(1)–Sn
C(3)–N(2)–Sn
C(2)–C(1)–N(1)
C(3)–C(2)–C(1)
N(2)–C(3)–C(2)
87.35(11)
91.98(9)a
92.53(8)a
117.5(2)
116.8(2)
125.3(3)
128.5(3)
126.4(3)
86.5(2)
91.7(2)
90.6(2)
120.1(5)
129.1(5)
127.1(7)
129.5(7)
120.8(7)
83.1(3)
88.8(3)
95.6(3)
130.4(7)
129.9(8)
122.5(11)
129.1(11)
123.0(10)
84.9(3)
90.6(3)
93.4(2)
125.7(7)
127.5(7)
125.5(11)
127.7(13)
123.9(11)
85.21(8)
90.97(6)
93.47(6)
125.2(2)
123.8(2)
123.7(2)
129.6(2)
124.0(2)
87.38(17)
90.52(9)
90.52(9)
122.1(2)
122.1(2)
124.9(4)
129.3(5)
124.9(4)
i
L6 = [{N(Ph)C(Me)}2CH]; L7= [{N(C6H3 Pr2-2,6)C(Me)}2CH]; L8 = [{N(C6H2Me3-2,4,6)C(Me)}2CH].a 3 mixed halide (0.4 Cl : 0.6 Br).
Table 2 Selected geometric data illustrating the conformation of the
NCCCNSn ring in 3, 5, 6, 8 and 11
Parametera
a/◦
b/◦
˚
a/A
˚
b/A
Sn(L1)Cl/Br (3)b
Sn(L3)Cl (5)
0.89
0.50
0.25
0.16
0.09
0.13
0.07
0.03
0.04
0.02
34.5
18.8
9.2
5.9
3.8
12.3
7.6
3.1
4.3
2.3
Sn(L4)Cl (6)
Sn(L1)NR2 (8)
Sn(L4)NR2(=S) (11)
a For parameters, see VI. b 3 mixed halide (0.4 Cl : 0.6 Br).
Scheme 2 Synthesis of complexes 8–12 (R = SiMe3).
solvent-free (b-diketiminato)tin(II) amide 8, obtained as orange
crystals from a saturated solution in light petroleum (bp 60–
80 ◦C). It was extremely soluble in hydrocarbons. Complex
1
1
8 was fully characterised by 1H-, 13C{ H}-, 29Si{ H}- and
1
1
119Sn{ H}-NMR spectroscopy. The 29Si{ H}-NMR spectrum
showed singlets at d −1.11 and d + 8.76, which correspond to
the trimethylsilyl group of the amido and b-diketiminato ligands,
respectively. Each signal showed satellites, 2J(29Si–117Sn/119Sn) =
26.3 Hz (d −1.11) and 26.4 Hz (d +8.76). The room temperature
13C{ H}-NMR spectrum showed resonances at d +3.91 and d
1
+6.65, each with satellites from both J(13C–29Si) = 56.3 Hz
1
(d +3.91) and 57.8 Hz (d +6.65) and 3J(13C–117Sn/119Sn) =
48.4 Hz (d +3.91) and 29.9 Hz (d +6.65). Hence the d +
3.91 signal is assigned to NR2 and the d +6.65 to the b-
Fig. 4 2D EXSY 119Sn-NMR spectra for 3a/3b.
Synthesis and characterisation of the b-diketiminatotin(II)
bis(trimethylsilyl)amide 8 and of four of its reaction products
9–12
diketiminato groups R. The 119Sn{ H}-NMR spectra showed
1
a singlet at d −110.74, a similar value to that of the amidotin(II)
b-diketonate Sn({OCC(But)}2CH)NR2, d −127.0 (C6D6/C6H6,
298 K).16 Variable temperature 1H-NMR spectral chemical shift
data were collected for complex 8, but showed no significant
variation with temperature, consistent with there being little
restriction to rotation about the Sn–NR2 bond. This is a contrast
with the situation in [Sn{C(R)2(NC5H4-2)}{NR2}], which had
The syntheses of the b-diketiminatotin(II) compounds 8–10
and of the chalcogenotin(IV) oxidative adducts 11 and 12 are
summarised in Scheme 2.
The reaction of Sn(L1)Cl 3a with one equivalent of
NaN(SiMe3)2 in diethyl ether afforded [(i) in Scheme 2] the
4 1 9 6
D a l t o n T r a n s . , 2 0 0 4 , 4 1 9 3 – 4 2 0 1

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to be heated to 368 K before the N(SiMe3)2 1H resonances
coalesced.
Crystal structures of compounds 8 and 11
5l
Complexes 8 and 11 are monomeric in the solid with a three- and
four-coordinate tin centre, respectively. Compound 8 contains
two independent molecules in the unit cell, having essentially
the same geometry. The molecular structures of complexes 8
and 11, with the atom numbering scheme, are shown in Figs. 5
(molecule A) and 6, respectively. Selected bond distances and
angles for 8 and 11 are in Table 3.
The reaction of the amide 8 with one equivalent of CF3SO3H
in diethyl ether afforded [(ii) in Scheme 2] the solvent-free (b-
diketiminato)tin(II) triflate 9, as a yellow crystalline solid. It was
insoluble in aliphatic hydrocarbons, possibly indicative of its
1
ionic structure. It was fully characterised by multinuclear H-
1
1
1
,
13C{ H}-, 29Si{ H}- and 119Sn{ H}- NMR spectroscopy. The
13C{ H}-NMR spectrum in PhMe/C6D6 at ambient tempera-
ture showed a quartet centred at d 120.4 (1J(13C–19F) = 312 Hz).
1
The 119Sn{ H}-NMR spectrum in PhMe/C6D6 at ambient
1
temperature showed a signal at d −299.7, which suggests that
the tin may be four-coordinate.
The reaction of the amide 8 with one equivalent of dibenzoyl-
methane in diethyl ether afforded [(iii) in Scheme 2] the solvent-
free (b-diketiminato)tin(II) b-diketonate 10. Alternatively, 10 was
synthesised by reacting Sn({OCC(Ph)}2CH)2 with an equivalent
portion of [Li(L1)]2. Complex 10 was obtained as yellow
crystals from a saturated solution in diethyl ether. It was
insoluble in aliphatic hydrocarbons. It was fully characterised
1
1
1
by 1H-, 13C{ H}-, 29Si{ H}- and 119Sn{ H}-NMR spectroscopy.
The 119Sn{ H}-NMR spectrum at ambient temperature in
1
PhMe/C6D6 showed a signal at d −66.65. This was unexpected,
as the bis(b-diketonato)tin(II) complex Sn({OCC(But)}2CH)2
had d −710.7 in PhMe/C6D6.16
Treatment of the amide 8 with one equivalent of either freshly
sublimed sulfur or elemental Se in toluene afforded [(iv) in
Scheme 2] the (b-diketiminato)(amido)tin(IV) sulfide or selenide
11 or 12, having a terminal S2− or Se2− ligand. Complexes 11
Fig. 5 Molecular structure of 8 (molecule A); hydrogen atoms are
omitted for clarity. Thermal ellipsoids are shown at the 50% probability
level.
and 12 were fully characterised by 1H-, 13C{ H}-, 29Si{ H}- and
1
1
119Sn{ H}-NMR spectroscopy (C6H6/C6D6, 298 K). The H-,
1
1
13C{ H}- and 29Si{ H}-NMR spectra were essentially identical
1
1
to those of 8. The 29Si{ H}-NMR spectrum of 11 showed two
1
singlets at d −0.08 and d + 9.89. Each signal featured satellites
from 2J(29Si–117Sn/119Sn) = 27.8 Hz (d −0.08) and 27.6 Hz (d +
9.89), corresponding to the trimethylsilyl group of the amido and
b-diketiminato ligands, respectively. Compound 12 had singlets
at d −0.92 and d +9.78, with satellites from 2J(29Si–117Sn/119Sn) =
27.5 Hz (d −0.72) and 27.9 Hz (d +9.78). The 13C{ H}- NMR
1
spectrum of the sulfide 11 showed resonances at d +4.01 and d
+7.03, each with satellites from both J(13C–29Si) = 56.93 Hz
1
(d +4.01) and 58.7 Hz (d +7.03) and 3J(13C–117Sn/119Sn) =
46.76 Hz (d +4.01) and 31.2 Hz (d +7.03). The selenide 12
showed resonances at d +4.01 and d +7.03; each with satellites
from both J(13C–29Si) = 56.01 Hz (d +3.87) and 56.3 Hz (d
1
+6.78) and 3J(13C–117Sn/119Sn) = 45.45 Hz (d +3.87) and 27.8 Hz
Fig. 6 Molecular structure of 11; hydrogen atoms are omitted for
clarity. Thermal ellipsoids are shown at the 50% probability level.
(d +6.78). The 119Sn{ H}-NMR chemical shift was identical for
1
11 and 12, d −141.1.
Thermally stable heavier Group 14 metal chalcogenides
generally have bridging E2− ligands, as in [M(NR2)2(l-E)]2 (M =
◦
˚
Table 3 Selected bond distances (A) and angles ( ) for 8 and 11
17a
Ge or Sn; E = S, Se, Te), (R2N)2Ge(l-E)2Sn(NR2)2 (E = Se or
Bond
8
11
t
t
17a
17b
Te), [Ge(CH2Ph)(NR2)(l-S)]2, or [Me2SiN(Bu )MN(Bu )(l-
E)]2,18 obtained from the appropriate metal(II) amide and
E. The first terminal metal sulfide was the polymeric, crys-
talline cage compound Ge(S)[N(But)Si(Me)]2.19 Later examples
Sn–N(1)
Sn–N(2)
Sn–N(3)
Sn–S
N(1)–C(1)
N(2)–C(3)
C(1)–C(2)
C(2)–C(3)
2.229(12)
2.221(14)
2.162(13)
N.A.
1.327(17)
1.332(19)
1.425(18)
1.38(2)
2.119(3)
2.134(3)
2.046(3)
2.2555(19)
1.344(5)
1.335(5)
1.387(5)
1.401(6)
20a
include Sn(E)[CX(R)C9H6N-8]2 (E = S or Te and X = H;
20b
or E = S, Se or Te and X = Ph ), Ge(E)[CR2(C5H4N-
2)]2 (E = S, Se or Te),21 M(E)(g -Me8taa) (M = Ge and
4
4
22a
22b
E = S, Se or Te; or M = Sn and E = S or Se; [g -
Me8taa]2− = octamethyl-dibenzotetraaza[14]annulene dianion),
and Sn(S)[{N(C6H11-c)}2CBut]2.23 Unlike the four-coordinate
tin compounds 11 and 12, these have five-coordinate M atoms.
The b-diketiminatometal(II) chlorides M[{N(Ph)C(Me)}2CH]Cl
(M = Ge or Sn (i.e., ML6Cl)) with sulfur in refluxing toluene
yielded green precipitates, soluble only in a polar solvent such
as Me2SO, believed to have the empirical formulae of 1 : 1-
adducts; only the germanium compound was sufficiently stable
to be analytically characterised;8 later work led to the X-ray
N(1)–Sn–N(2)
N(1)–Sn–N(3)
N(2)–Sn–N(3)
N(1)–Sn–S
N(2)–Sn–S
N(3)–Sn–S
C(1)–N(1)–Sn
C(3)–N(2)–Sn
C(2)–C(1)–N(1)
C(3)–C(2)–C(1)
N(2)–C(3)–C(2)
91.2(4)
99.3(4)
98.1(5)
N.A.
N.A.
N.A.
121.2(10)
124.0(11)
126.1(15)
132.4(15)
128.2(14)
96.67(13)
103.90(13)
105.49(14)
109.94(10)
109.03(10)
127.44(10)
118.0(3)
118.0(3)
127.7(3)
132.2(4)
127.2(4)
6
24a
authenticated compounds Ge(E)(L )Cl (E = S or Se) and
7
24b
Ge(S)(L )X (X = F, Cl or Me).
D a l t o n T r a n s . , 2 0 0 4 , 4 1 9 3 – 4 2 0 1
4 1 9 7

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1
Table 4 Comparison of bond lengths, coordination number (C.N.) and 119Sn{ H}-NMR data
1
119Sn{ H} (d)
Ref.
˚
Complex
Sn–S/A
C.N.
Sn(l-S)[CH(R)(C9H6N-8)]2
Sn(l-S)[CPh(R)(C5H3N-2)]2
Sn(S)[{N(C6H11-c)}2CBut]2
2.420(3)
2.528(7)
2.280(5)
2.274(3)
n.d.
6
5
5
5
4
4
−100.48a
−54.70a
−236.2b
20a
20b
23
22b
21
4
Sn(S){g -Me8taa}
Sn(S)(L6)Cl
−228
Sn(S)(L1)(NR2) (11)
2.256(2)
−141.1c
This work
a C6D6/thf. b C6D6. c C7D8.
The conformation of the b-diketiminatotin moiety in each
of 8 and 11 is compared with those in 3, 5, and 6 in Table 2.
The two sets of endocyclic N–C and C–C bond lengths for 8
and 11 reveal that there is significant p-delocalisation within
the b-diketiminato ligand. The Sn–NR2 (Sn–N3) bond length
Melting points were determined under argon in sealed capillaries
on an electrothermal apparatus and were uncorrected. NMR
spectra were recorded using a Bruker AC-P250 (1H, 250.1;
13C 62.9; 93.24 MHz), WM 360 (1H, 360.1 MHz), DPX-300
(1H, 300.1; 13C 75.5 MHz), AMX-400 (1H, 400.1; 13C 100.6;
119Sn 149.19 MHz), or AMX-500 (1H, 500.1; 13C, 125.7; 29Si,
99.3; 186.48 MHz) spectrometers and referenced to residual
solvent resonances (data in d), in the case of 1H and 13C-spectra.
The 29Si- and 119Sn-spectra were referenced externally to SiMe4
and SnMe4. Unless otherwise stated all NMR spectra other
than 1H were proton-decoupled and recorded at ambient probe
temperature.
in 8 is unexceptional [cf.,5l 2.114(5) A for the corresponding
˚
parameter in I], but is significantly longer than in 11, which is
attributed to the smaller tin(IV) radius in 11 than the tin(II) in
8. The Sn–S bond length in 11 is shorter than in the known
five-coordinate-tin sulfides; comparative data are in Table 4,
1
which also lists values for 119Sn{ H}-NMR chemical shifts in
solution. As for the latter parameter, a value of d −228 in
(CD3)2SO was recorded for the compound of empirical formula
Sn(S)[{N(Ph)C(Me)}2CH]Cl, even though the compound was
said to be highly unstable in solution.8
[Sn({N(SiMe3)C(Ph)} CH)X] (X = Cl/Br) (3). A solution
of [(Li{N(SiMe3)C(Ph)}22CH)2] (1.3 g, 1.75 mmol) in Et2O (ca.
20 cm3) was slowly added to a stirred suspension of SnCl2 (0.33 g,
1.75 mmol) in Et2O (ca. 10 cm3) at −78 ◦C. The suspension
was allowed to warm to room temperature and stirred for 3 h,
then filtered. The solvent was removed from the filtrate in vacuo
and the residue was washed with light petroleum (bp 60–80 ◦C,
ca. 10 cm3) to afford a yellow solid. Complex 3 (1.3 g) slowly
crystallised from Et2O (30 cm3) by concentrating to ca. 5 cm3
over a period of 4 h.
In conclusion, the present study has contributed to the chem-
istry of b-diketiminatotin(II) compounds in the following ways
(i)–(v), using the N,N1-bidentate chelating ligands [N(R1)C(R3)
C(H)C(R4)NR2]− [L1: R1 = SiMe3 = R2, R3 = Ph = R4; L2: R1 =
SiMe3 = R2, R3 = Ph, R4 = But; L3: R1 = SiMe3, R2 = H, R3 =
Ph, R4 = But; L4: R1 = H = R2, R3 = Ph, R4 = But; L5: R1 =
H = R2, R3 = Ph = R4]. (i) Homoleptic compounds Sn(L1)2 or
Sn(L2)2 proved to be inaccessible; thus the compounds Sn(L1)Cl
(3a), Sn(L1)Br (3b) or Sn(L2)Cl (4) were resistant to nucleophilic
attack by [L1]− or [L2]−. (ii) The trimethylsilyl substituents at the
nitrogen atoms of L1 or L2 were readily and regiospecifically (for
4, the SiMe3 proximal to the But was preferentially hydrolysed)
cleaved in a stepwise fashion, yielding Sn(L3)Cl (5), Sn(L4)Cl
(6) or Sn(L5)Cl (7). (iii) The halide exchange in PhMe/C6D6
between 3a and 3b is believed to implicate a (l-Cl)(l-Br)-
Sn({N(SiMe3)C(Ph)}2CH)Cl (3a). A solution of [(Li{N
(SiMe3)C(Ph)}2CH)2] (1.4 g, 4.5 mmol) in Et2O (ca. 30 cm3) was
slowly added to a stirred suspension of SnCl2 (0.43 g, 2.3 mmol)
in Et2O (ca. 10 cm3) at room temperature. The suspension was
allowed to stir for 13 h, filtered and solvent was removed from the
filtrate in vacuo to afford a ◦yellow solid, which was washed with
light petroleum (bp 60–80 C, ca. 10 cm3) to afford complex 3a
(0.93 g, 78%) (Found: C, 44.1; H 5.64; N 5.32. C21H29ClN2Si2Sn
requires C, 44.7; H, 5.58; N, 5.39%). 1H-NMR (360 MHz, C6D6):
dinuclear intermediate, while DG‡
for Sn–X was evaluated
338 K
as 69.4 (3a, X = Cl) and 72.8 (3b, X = Br) KJ mol−1. (iv)
Compound Sn(L1)Cl was shown to be susceptible to nucleophilic
attack giving Sn(L1)X [X = N(SiMe3)2 (8), O3SCF3 (9) or
{OC(Ph)}2CH (10)], while oxidative addition to 8 afforded the
tin(IV) terminal chalcogenides Sn(E)(L1){N(SiMe3)2} [E = S (11)
or Se (12)]. (v) The X-ray structures of the crystalline complexes
3a/3b, 5, 6, 8, and 11 have been determined; data for 4 are also
available.25
4
d 0.06 (s, 18 H, J(1H–117Sn/119Sn) = 6.9 Hz, Si(CH3)3), 5.64
(s, 1 H, CH), 6.93 (m, 6 H, C6H5), 7.27 (m, 4 H, C6H5). 13C-
NMR (62.9 MHz, C6D6): d 2.2 (s, 3J(13C–117Sn/119Sn) = 52.9 Hz,
Si(CH3)3), 112.8 (s, CH), 127–130 (m, C6H5), 144.9 (s, Cipso),
173.2 (s, C N). 29Si-NMR (93.2 MHz, C6D6/C6H6): d 11.5.
=
119Sn-NMR (93.2 MHz, C6D6/C6H6): d −118.2. MS (EI. 70 eV):
m/z 520 [M]+; 485 [M − L1]+; 412 [M − L1 − SiMe3]+; 365 [L1]+.
Experimental
Sn({N(SiMe3)C(Ph)}2CH)Br (3b). A solution of [(Li{N
(SiMe3)C(Ph)}2CH)2] (1.63 g, 2 mmol) in Et2O (ca. 30 cm3) was
slowly added to SnBr2 (0.30 g, 1 mmol) in Et2O (ca. 5 cm3) at
room temperature. The suspension was allowed to stir for 5 h,
then filtered and solvent removed from the filtrate in vacuo to
afford a ye◦llow solid, which was washed with light petroleum
(bp 60–80 C, ca. 10 cm3) to afford complex 3b (0.50 g, 83%)
(Found: C, 43.4; H 5.19; N 5.09. C21H29BrN2Si2Sn requires C,
44.6; H, 5.20; N, 5.01%). 1H-NMR (360 MHz, C6D6): d 0.06 (s,
18 H, 4J(1H–117Sn/119Sn) = 6.9 Hz, Si(CH3)3), 5.64 (s, 1 H, CH),
6.93 (m, 6 H, C6H5), 7.27 (m, 4 H, C6H5). 13C-NMR (62.9 MHz,
C6D6): d 2.2 (s, 3J(13C–117Sn/119Sn) = 53.1 Hz, Si(CH3)3)), 113.4
General procedures
All experiments were performed under an atmosphere of pure
argon using Schlenk apparatus and a vacuum line, unless oth-
erwise stated. The solvents used were of reagent grade or better
and were freshly distilled under dry dinitrogen and freeze/thaw
degassed prior to use. The drying agents used were as follows:
(i) sodium benzophenone (benzene, diethyl ether, toluene and
dme); and (ii) sodium–potassium alloy (light petroleum, bp 30–
40 and 60–80 ◦C). Reaction solvents and deuterated solvents for
NMR spectroscopy were stored over a potassium mirror (C6D6
and C7D8). Elemental analyses were performed on a CEC 240
XA analyser by Medac Ltd, Brunel University. MS data were
recorded using a VG Autospec or Kratos MS 80 RF instruments:
EI 70 eV. The carrier gas was helium, at a flow rate 2 cm3 min−1.
(s, CH), 127–130 (m, C6H5), 144.7 (s, Cipso), 173.5 (s, C N). 29Si-
=
NMR (93.2 MHz, C6D6/C6H6): d11.6. 119Sn-NMR (93.2 MHz,
C6D6/C6H6): d −64.5. MS (EI. 70 eV): m/z 565 [M]+; 485 [M −
L1]+; 412 [M − L1 − SiMe3]+; 365 [L1]+.
4 1 9 8
D a l t o n T r a n s . , 2 0 0 4 , 4 1 9 3 – 4 2 0 1

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◦
Sn{N(SiMe3)C(Ph)CHC(But)N(SiMe3)}Cl (4). Dry solid
SnCl2 (0.19 g, 1.00 mmol) was added to a stirred solution of
K(L2) (0.39 g, 1.00 mmol) in thf (ca. 100 cm3) at ca. 0 ◦C. The
reaction mixture was warmed to room temperature and stirred
for a further 24 h. The solvent was removed in vacuo and
the residue extracted with light petroleum (bp 60–80 ◦C, ca.
100 cm3). The volume of the filtrate was reduced to ca. 25 cm3,
and cooling to −30 ◦C yielded the light yellow crystalline
compound 4 (0.32 g, 64%) (Found: C, 44.8; H 6.2; N 5.4.
diffraction study were obtained, mp 87 C (Found: C, 49.9; H
7.25; N 6.50. C27H47N3Si4Sn requires 50.2; H, 7.30; N, 6.5%). 1H-
NMR (300 MHz, C6D6): d 0.08 (s, 18 H, 4J(1H–117Sn/119 Sn) =
6.89 Hz, Si(CH3)3), 0.28 (s, 18 H, 4J(1H–117Sn/119Sn) = 9.87 Hz,
Si(CH3)3), 5.51 (s, 1 H, CH), 7.32 (m, 8 H, C6H5), 7.84 (m,
2 H, C6H5). 13C-NMR (75.5 MHz, C6D6): d 3.91 (s, J(13C–
1
29Si) = 56.3 Hz, 3J(13C–117Sn/119Sn) = 48.4 Hz), Si(CH3)3),
6.65 (s, 1J(13C–29Si) = 57.8 Hz, J(13C–117Sn/119Sn) = 29.9 Hz),
3
Si(CH3)3)) 112.1 (s, CH), 127–129 (m, C6H5), 144.7 (s, Cipso),
173.5 (s, C N). 29Si-NMR (99.4 MHz, C6D6/C6H6): d −1.11 (s,
1
=
C19H33ClN2Si2Sn requires C, 45.7; H, 6.7; N, 5.6%). H-NMR
2J(29Si–117Sn/119Sn, = 26.3), 8.75 (s, 2J(29Si–117Sn/119Sn, = 26.4).
119Sn-NMR (186.5 MHz, C6D6/C6H6): d −110.7. MS (EI. 70
eV): m/z 645 [M]+; 630 [M − Me]+; 485 [M − N(SiMe3)2]+; 412
[M − L1 − SiMe3]+; 365 [L1]+.
(360 MHz, C6D6): d −0.07 (s, 9 H, Si(CH3)3), 0.27 (s, 9 H,
Si(CH3)3), 1.13 (s, 9 H, C(CH3)3), 6.00 (s, 1 H, CH), 6.90 (m, 3
H, C6H5), 7.00 (m, 2 H, C6H5). 119Sn-NMR (93.2 MHz, C6D6):
d −118.0. MS (EI. 70 eV): m/z 499 (M+).
[Sn{N(SiMe3)C(Ph)CHC(But)N(H)}Cl] (5). A mixture of
SnCl2·2H2O (0.23 g, 1.00 mmol) and SnCl2 (0.19 g, 1.00 mmol)
was added in portions to a stirred solution of K(L2) (0.78 g,
2 mmol) in thf (ca. 100 cm3) at ca. −78 ◦C for 3 h until
all solid had dissolved. The reaction mixture was warmed to
room temperature and stirred for a further 24 h. The solvent
was removed in vacuo◦and the residue washed with cold light
petroleum (bp 60–80 C, ca. 10 cm3) and extracted with hot
light petroleum (bp 60–80 ◦C, ca. 100 cm3). Cooling the extract
to −30 ◦C yielded light yellow crystals of compound 5 (0.52 g,
61%) (Found: C, 43.5; H 5.9; N 6.7. C16H25ClN2SiSn requires C,
44.9; H, 5.9; N, 6.6%). 1H-NMR (360 MHz, C6D6): d 0.06 (s, 9
H, Si(CH3)3), 1.13 (s, 9 H, C(CH3)3), 5.45 (d, 1 H, CH), 7.03
(m, 3 H, C6H5), 7.41 (m, 2 H, C6H5). 119Sn-NMR (93.2 MHz,
C6D6): d −166.5. MS (EI. 70 eV): m/z 428 (M+).
Sn({N(SiMe3)C(Ph)}2CH)(CF3SO3) (9). Trifluromethylsul-
fonic acid (1.3 cm3, 1.5 mmol) was added slowly to a solution
of 8 (0.98 g, ◦1.5 mmol) in light petroleum (bp 60–80 ◦C, ca.
30 cm3) at 0 C. The orange mixture was allowed to warm to
room temperature and stirred for a further 18 h. A bright yellow
solution was obtained with a bright yellow precipitate, which
was collected and washed with light petroleum (bp 30–40, ca.
2 × 20 cm3). The solid was dissolved in toluene (ca. 40 cm3),
concentrated to ca. 10 cm3 and cooled to 4 ◦C to afford crystals
of complex 9 (0.67 g, 70%), mp < 180 ◦C (decomp.) (Found: C,
55.5; H 4.95; N 5.00. C22H29F3N2O3SSi2Sn requires C, 56.2; H,
1
4.85; N, 4.70%). H-NMR (400 MHz, C6D6): d 0.09 (s, 18 H,
4J(1H–117Sn/119Sn) = 6.81 Hz, Si(CH3)3), 5.52 (s, 1 H, CH), 7.29
(m, 6 H, C6H5), 7.35 (m, 4 H, C6H5). 13C-NMR (100.6 MHz,
3
C6D6): d 3.69 (s, J(13C–117Sn/119Sn) = 52.38 Hz, Si(CH3)3)),
[Sn{N(H)C(Ph)CHC(But)N(H)}Cl] (6). Solid SnCl2·2H2O
(0.52 g, 2.29 mmol) was added in portions to a stirred soluti◦on
of KL2 (0.88 g, 2.29 mmol) in thf (ca. 100 cm3) at ca. −78 C
for 2 h until all solid had dissolved. The reaction mixture was
warmed to room temperature and stirred for a further 24 h. The
solvent was removed in vacuo and the residue extracted with
toluene (ca. 100 cm3). The volume of the filtrate was reduced to
ca. 25 cm3, and cooling to −30 ◦C yielded light yellow crystals
of the compound 6 (0.79 g, 97%) (Found: C, 43.8; H 4.9; N
7.3. C13H17ClN2Sn requires C, 43.9; H, 4.8; N, 7.9%). 1H-NMR
(360 MHz, C6D6): d 0.90 (s, 9 H, C(CH3)3), 5.31 (s, 1 H, CH), 6.34
(s, 1 H, C(But)NH), 7.02 (m, 3 H, C6H5), 7.24 (m, 2 H, C6H5),
8.14 (br., 1 H, C(Ph)NH). 119Sn-NMR (93.2 MHz, C6D6): d
−216.9. MS (EI. 70 eV): m/z 356 (M+).
[Sn({N(H)C(Ph)}2CH)Cl] (7). Solid SnCl2·2H2O (0.61g,
2.70 mmol) was added in portions to a stirred solution ◦of
1/2[Li(L1)]2 (0.95 g, 2.70 mmol) in thf (ca. 100 cm3) at ca. −78 C
for 2 h until all solid had dissolved. The reaction mixture was
warmed to room temperature and stirred for a further 24 h. The
solvent was removed in vacuo and the residue extracted with
toluene (ca. 100 cm3). The volume of the filtrate was reduced to
ca. 25 cm3, and cooling to −30 ◦C yielded light yellow crystals
of compound 7 (0.87 g, 91%) (Found: C, 47.1; H 3.4; N 7.2.
C13H12ClN2Sn requires C, 48.0; H, 3.5; N, 7.5%). 1H-NMR
(360 MHz, C6D6/C4D8O): d 5.63 (s, 1 H, CH), 7.37 (m, 4 H,
C6H5), 7.63 (m, 6 H, C6H5), 8.01 (b, 2 H, C(Ph)NH). 119Sn-NMR
(93.2 MHz, C6D6/C4D8O) d −189.9. MS (EI. 70 eV): m/z 376
(M+).
112.86 (s, CH), 127–130 (m, C6H5), 120.4 (s, 1J(13C–19F) =
312 Hz, O3SCF3) 143.4 (s, Cipso), 173.1 (s, C N). 29Si-NMR
=
(79.5 MHz, C6D6/C6H6): d 11.56. 119Sn-NMR (149.5 MHz,
C6D6/C6H6): d −299.71. MS (EI. 70 eV): m/z 485 [M −
O3SCF3]+; 412 [M − L1 − SiMe3]+; 365 [L1]+.
Sn({N(SiMe3)C(Ph)}2CH)({OC(Ph)}2CH) (10).
(a) From Sn({OC(Ph)}2CH)2. A solution of [(Li-
{N(SiMe3)C(Ph)}2CH)2] (2.5 g, 3.36 mmol) in Et2O (ca. 20 cm3)
was added slowly to a stirred suspension of Sn({OC(Ph)}2CH)2
(0.44 g, 3.36 mmol) in Et2O (ca. 10 cm3) at −78 ◦C. The
suspension was allowed to warm to room temperature and
stirred for a further 18 h. A dark yellow solution was filtered
off from a white precipitate. The solvent was removed from the
filtrate in vacuo to afford a dark yellow solid, which was washed
with light petroleum (bp 60–80 ◦C, ca. 10 cm3) to give 10 (2.11 g,
89%), as a bright-yellow, free-flowing solid.
(b) from 8. A solution of 8 (0.71 g, 1.1 mmol) in Et2O (ca.
30 cm3) was added slowly to a stirred solution of dibenzoyl-
methane (0.25 g, 1.1 mmol) in Et2O (ca. 20 cm3). The bright-
orange solution was stirred for a further 36 h, becoming golden
yellow. The slight precipitate was filtered off. Diethyl ether was
removed from the filtrate in vacuo and the resultant yellow solid
“stripped” twice with light petroleum (bp 30–40 ◦C, ca. 2 ×
20 cm3), then was washed with cold light petroleum (bp 60–
◦
80 C, ca. 15 cm3, −30 ◦C) and crystallised from Et2O (ca.
30 cm3) by slowly concentrating to ca. 10 cm3 over a period of
4 h to give 10 as yellow feathery crystals (0.66 g, 85%), mp 172 ◦C
(Found: C, 60.7; H 5.60; N 3.85. C36H40N2O2Si2Sn requires C,
61.0; H, 5.65; N, 3.95%). 1H-NMR (300 MHz, CDCl3): d 0.11 (s,
18 H, 4J(1H–117Sn/119Sn) = 6.98 Hz, Si(CH3)3), 5.54 (s, 1 H, CH),
6.66 (s, 1 H, CH), 7.40 (m, 16 H, C6H5), 7.85 (m, 4 H, C6H5).
[Sn({N(SiMe3)C(Ph)}2CH)N(SiMe3)2] (8). Sodium bis(tri-
methylsilyl)amide (1.75 g, 9.6 mmol) was added to a cooled
(−30 ◦C) stirred solution of 3a (5 g, 9.6 mmol) in Et2O (ca.
30 cm3 ). The yellow mixture immediately turned bright orange
and was stirred for a further 3 h, then filtered. Solvent was
removed in vacuo from the filtrate and the resultant orange oily
solid “stripped” twice with light petroleum (bp 30–40 ◦C, ca.
15 cm3 ) to afford complex 8 (6.02 g, 87%). Complex 8 (ca.1 g)
was dissolved in hot benzene (ca. 5 cm3 ), placed in a Dewar
vessel filled with hot water (ca. 70 cm3) and allowed to cool
slowly. After 3 d, crystals of 8 suitable for a single crystal X-ray
3
13C-NMR (75.5 MHz, CDCl3): d 3.73 (s, J(13C–117Sn/119Sn) =
51.29 Hz, Si(CH3)3)), 92.2 (s, CH), 113.6 (s, CH), 127–130 (m,
=
C6H5), 138.8, (s, Cipso),144.6 (s, Cipso), 173.4 (s, C N), 183.4
(s, C O). 29Si-NMR (79.5 MHz, CDCl3): d 10.84. 119Sn-NMR
=
(149.5 MHz, C6D6/C6H6): d −66.65. MS (EI. 70 eV): m/z 708
[M]+; 485 [M − {OC(Ph)}2CH]+; 412 [M − L1 − SiMe3]+; 365
[L1]+
D a l t o n T r a n s . , 2 0 0 4 , 4 1 9 3 – 4 2 0 1
4 1 9 9

View Article Online
Table 5 Crystal data and refinement details for compounds 3, 5, 6, 8 and 11
3
5
6
8
11
Empirical formula
M
C21H29Br0.6Cl0.4N2Si2Sn
546.64
C16H25ClN2SiSn
427.61
C13H17ClN2Sn.(C7H8)1/2
C27H47N3Si4Sn
644.73
C27H47N3SSi4Sn
676.79
401.50
Monoclinic
P21/c (no. 14)
11.280(6)
25.044(12)
12.767(8)
90
107.19(3)
90
3446(3)
4
1608
1.63
4776
3434
0.074
0.177
0.107, 0.199
Crystal system
Space group
Triclinic
P1 (no. 2)
6.434(1)
11.986(4)
17.262(1)
98.87(2)
100.23(1)
104.26(2)
1242.0(5)
2
550
2.15
5978
4008
Monoclinic
P21/n (no. 14)
24.938(8)
6.302(1)
24.981(10)
90
99.52(3)
90
3872(2)
8
1728
1.52
4738, 0.039
3333
0.046
Monoclinic
P21/n (no. 14)
21.258(4)
9.153(2)
36.160(5)
90
104.90(1)
90
6799(2)
8
2688
0.91
11921, 0.091
4388
0.095
Monoclinic
P21/n (no. 14)
18.795(5)
8.974(6)
21.617(3)
90
105.82(2)
90
3508(3)
4
1408
0.94
6149, 0.025
4256
0.040
˚
a/A
˚
b/A
˚
c/A
a/◦
b/◦
c /◦
U/A
Z
3
˚
F(000)
l(Mo-Ka)/mm−1
Unique reflections, Rint
Reflections with [I > 2r(I)]
R1 [I > 2r(I)]
0.045
0.087
0.084, 0.101
wR2 [I > 2r(I)]
Rindices (all data)R1,wR2
0.085
0.081, 0.097
0.195
0.252, 0.269
0.080
0.073, 0.092
293 K for 3, 8, and 11 or at 173(2) K for 5 and 6. Crystals were
coated in oil and then directly mounted on the diffractometer
under a stream of cold nitrogen gas for 5 and 6, or in a sealed
capillary for 3, 8 and 11. The structures were refined on all F2
using SHELXL-97.25 The halide ligand in 3 was an unresolved
mixture of Br and Cl in a ratio which refined to 0.6 : 0.4. There
were two independent molecules of 5; in one, the C(26)But group
had the methyl carbon atom disordered unequally over two
orientations and the lower occupancy carbon atom sites were left
isotropic. The C6 ring of the toluene solvate in 6 was included as
a rigid body. Absorption correction from w scans were applied
for 3, 5, 6, 11, but not 8. Further details are found in Table 5.
Data for 4,26 which are very similar to those of 3a, are found in
CCDC 253948.
[Sn(S)({N(SiMe3)C(Ph)}2CH)N(SiMe3)2] (11). Freshly sub-
limed elemental sulfur (0.03 g, 0.9 mmol) was added to a solution
of 8 (0.49 g, 0.8 mmol) in toluene (ca. 20 cm3). The orange
suspension was stirred for a further 18 h until a clear yellow
solution was obtained. The slight precipitate was filtered off.
The filtrate was slowly concentrated to ca. 10 cm3, warmed and
placed in a Dewar vessel filled with hot water (ca. 80 ◦C). After 3–
4 d pale yellow single crystals of 11 were obtained (0.39 g, 61%),
mp 112 ◦C (Found: C, 47.2; H 7.05; N 6.10. C27H47N3SSi4Sn
requires C, 47.8; H, 6.95; N, 6.20%). 1H-NMR (300 MHz, C7D8):
d 0.10 (s, 18 H, 4J(1H–117Sn/119Sn) = 6.89 Hz, Si(CH3)3), 0.29 (s,
18 H, 4J(1H–117Sn/119Sn) = 9.81 Hz, Si(CH3)3), 5.52 (s, 1 H, CH),
7.32 (m, 8 H, C6H5), 7.83 (m, 2 H, C6H5). 13C-NMR (75.5 MHz,
C7D8): d 4.01 (s, 1J(13C–29Si) = 56.93 Hz, 3J(13C–117Sn/119Sn) =
1
3
46.76 Hz) Si(CH3)3), 7.03 (s, J(13C–29Si) = 58.7 Hz, J(13C–
CCDC reference numbers 247918–247922.
See http://www.rsc.org/suppdata/dt/b4/b412765j/ for crys-
tallographic data in CIF or other electronic format.
117Sn/119Sn) = 31.2 Hz), Si(CH3)3)) 113.3 (s, CH), 127–129 (m,
C6H5), 144.7 (s, Cipso), 174.6 (s, C N). 29Si-NMR (99.4 MHz,
=
2
2
C7D8): d −0.08 (s, J(29Si–117Sn/119Sn, = 27.8), 9.89 (s, J(29Si–
117Sn/119Sn, = 27.6). 119Sn-NMR (186.5 MHz, C7D8): d −141.1.
MS (EI 70 eV): m/z 677 [M]+; 662 [M − Me]+; 645 [M − S]+;
Acknowledgements
485 [M − N(SiMe3)2]+; 412 [M − L1 − SiMe3]+; 365 [L1]+
We thank EPSRC for the award of fellowship (for J. H.) and
for a CASE Award (for J. S.). We are grateful to Dr R. Wife of
SPECS & BioSPECS for his part in the CASE project.
.
Sn(Se)({N(SiMe3)C(Ph)}2CH)N(SiMe3)2 (12).
Elemental
selenium (0.70 g, 0.9 mmol) was added to a solution of 8 (0.56 g,
0.9 mmol) in toluene (ca. 20 cm3). The orange suspension was
heated to 80 ◦C and stirred for 2 h until a clear red solution was
obtained and no elemental selenium remained. The hot filtrate
was slowly concentrated to ca. 10 cm3. The warm concentrate
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117Sn/119Sn) = 9.84 Hz, Si(CH3)3), 5.53 (s, 1 H, CH), 7.32 (m, 8
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27.8 Hz), Si(CH3)3)) 113.3 (s, CH), 127–129 (m, C6H5), 144.5
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27.6). MS (EI. 70 eV): m/z 724 [M]+; 645 [M − Se]+; 485 [M −
N(SiMe3)2]+; 412 [M − L1 − SiMe3]+; 365 [L1]+.
Crystal data and refinement details for 3, 5, 6, 8 and 11
Diffraction data were collected on a Nonius CAD4 diffractome-
˚
ter using monochromated Mo-Ka radiation, k 0.71073 A at
4 2 0 0
D a l t o n T r a n s . , 2 0 0 4 , 4 1 9 3 – 4 2 0 1

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D a l t o n T r a n s . , 2 0 0 4 , 4 1 9 3 – 4 2 0 1
4 2 0 1