New group 14 element(IV) β-diiminates and a Sn(II) analogue

Article abstract of DOI:10.1016/j.jorganchem.2009.03.044

Seven group 14 element(IV) compounds 2-7 have been prepared, derived either (2-5) from the potassium β-diketiminate K(L) [L = {N(Ar)C(Me)}₂CH, Ar = C₆H₃Prⁱ₂-2,6] (1) or the known lithium β-dialdiminate Li(L′)] [L′ = {N(Ar)C(H)}₂CPh, Ar = C₆H₃Prⁱ₂-2,6]. Treatment of 1 with Bu^tC(O)Cl, Me₃SiCl, Ph₃SnCl, or Me₃SnCl afforded {N(Ar)C(Me)}₂C(H)C(O)Bu^t (2), [ArNC(Me)C(H)C(Me)N(Ar)SiMe₃] (3), [HN(Ar)C(Me)C(H)C(CH₂SnPh₃)N(Ar)] (4), or {A figure is presented} (5), respectively. Compounds 4 and 5 are remarkable as they have arisen from a tautomer of 1; crystalline centrosymmetric 5 has a fused tricyclic structure, a central eight-membered ring flanked by two six-membered rings. The compounds [GeCl₂(L′)(OGeCl₃)] (6) or [SnCl(L′)Me₂] (7), the first group 14 metal β-dialdiminates, were obtained from Li(L′) and (GeCl₃)₂O or Me₂SnCl₂, respectively. The Sn(II) compound SnCl(L′) (8) was prepared from SnCl₂ and K(L′). The molecular structures of the crystalline compounds 3-8 are reported.

Full text of DOI:10.1016/j.jorganchem.2009.03.044

Journal of Organometallic Chemistry 694 (2009) 2611–2617
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Journal of Organometallic Chemistry
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New group 14 element(IV) b-diiminates and a Sn(II) analogue
*
David J. Doyle, Peter B. Hitchcock, Michael F. Lappert , Gang Li
Department of Chemistry and Biochemistry, University of Sussex, Brighton BN1 9QJ, UK
a r t i c l e i n f o
a b s t r a c t
Article history:
Seven group 14 element(IV) compounds 2–7 have been prepared, derived either ( 2–5) from the
potassium b-diketiminate K(L) [L = {N(Ar)C(Me)}2CH, Ar = C6H3Pri2-2,6] (1) or the known lithium b-
dialdiminate Li(L0)] [L0 = {N(Ar)C(H)}2CPh, Ar = C6H3Pri2-2,6]. Treatment of 1 with ButC(O)Cl, Me3SiCl,
Ph3SnCl, or Me3SnCl afforded {N(Ar)C(Me)}2C(H)C(O)But (2), [ArNC(Me)C(H)C(Me)N(Ar)SiMe3] (3),
Received 18 February 2009
Received in revised form 24 March 2009
Accepted 29 March 2009
Available online 5 April 2009
[HN(Ar)C(Me)C(H)C(CH2SnPh3)N(Ar)] (4), or
(5), respectively. Com-
Keywords:
pounds 4 and 5 are remarkable as they have arisen from a tautomer of 1; crystalline centrosymmetric 5
has a fused tricyclic structure, a central eight-membered ring flanked by two six-membered rings. The
compounds [GeCl2(L0)(OGeCl3)] (6) or [SnCl(L0)Me2] (7), the first group 14 metal b-dialdiminates, were
obtained from Li(L0) and (GeCl3)2O or Me2SnCl2, respectively. The Sn(II) compound SnCl(L0) (8) was pre-
pared from SnCl2 and K(L0). The molecular structures of the crystalline compounds 3–8 are reported.
Ó 2009 Elsevier B.V. All rights reserved.
b-Diiminate derivatives
Dimethylstannyl
Pivaloyl
Trimethylsilyl
Trichlorogermyloxygermyl
1. Introduction
2. Results and discussion
In the 2002 review of b-diketiminatometal complexes 10 differ-
ent uninegative ligand–metal bonding modes were described [1].
Six had the N,N’-chelating ligands in different conformations in
mono- or di-metal complexes, one in which the ligand was C-cen-
tred, two having the ligand N-centred or N,N’-bridging (in each of
This part is divided into four sections. Sections 2.1. and 2.2 deal
with the chemistry of compounds derived from ligand L, Section
2.3. describes the synthesis and structures of two group
14 metal(IV) b-dialdiminates, while the last relates to compound
SnCl(L0).
which there was substantial NCCCN
p-delocalisation), and finally
one in which an -methyl substituent had been deprotonated
a
2.1. Compounds derived from the potassium b-diketiminate K(L) (1)
(see Section 2.1). One of the most widely used b-diketiminate li-
gands is L.
The synthesis of 1 and its conversion into the colourless 2–4
b-Dialdiminatometal complexes, which have CH rather than CR
groups adjacent to the nitrogen atoms, are much rarer. One such
ligand, L0, was introduced in 2002 in the context of CuI chemistry
[2]. Other L0 metal complexes to have been described are the crys-
talline Tl(L0) [3], [Li(L0)(thf)2] [4], [MCl2(L0)] (M = Al, Ga) [4], and se-
ven InIII complexes of various types [4]. In each of these L0–metal
complexes, the ligand was bound to the metal in the N,N’-chelating
fashion.
and the yellow
Scheme 1.
5 crystalline derivatives are summarised in
The sparingly hexane-soluble crystalline potassium b-di-
ketiminate (1) was obtained as a precipitate by the metathetical
exchange reaction between [Li(L)(OEt2)] [5] and KOBut in hexane;
its purity was established by 1H NMR spectroscopy in a C6D6
solution. Similar high yield reactions led to C-pivaloyl (2) and N-
trimethylsilyl (3) b-diketiminates, from 1 and the appropriate chlo-
ride in toluene. Compound 2 was characterised by 1H and 13C{1H}
NMR spectra of its solution, which showed only one signal for the
The ligand L0 differs from L in that the possibility of substitution
reactions implicating the endocyclic carbon atoms of these metal
complexes is inhibited. Illustrated below are the ligands L and L0
a-Me substituents (cf. two such signals for 3), and its m(C@O)
in their monoanionic
p-delocalised form.
stretching frequency. For 3 the NMR data were supplemented by
determination of its molecular structure (Section 2.2).
The crystalline (from toluene), low melting 1,5-bis(2’,6’-diiso-
propylphenyl)-2-methyl-4-triphenylstannylmethyl-1,5-diazapent-
adiene (4) was prepared in good yield from equivalent portions of
K(L) (1) and chlorotri(phenyl)stannane in diethyl ether. Its unex-
pected constitution was established not only by 1H and 13C{1H}
NMR spectra of its solution, but also conclusively by its molecular
structure derived from a single crystal X-ray study (Section 2.2). It
* Corresponding author. Tel.: +44 1273 678316; fax: +44 1273 876687.
E-mail address: m.f.lappert@sussex.ac.uk (M.F. Lappert).
0022-328X/$ - see front matter Ó 2009 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2009.03.044

2612
D.J. Doyle et al. / Journal of Organometallic Chemistry 694 (2009) 2611–2617
Me
Me
Ar
O
But
Me
Me
Me
Ar
H
N
KOBut
N
N
But(O)Cl
Me
Ar
Ar
N
N
Li
O
−LiOBut
Ar
−KCl
K
N
Ar
1, 85%
Et
Ref. [5]
Et
2, 89%
Me3SnCl
Me3SiCl
−KCl, −CH4
Ph3SnCl
Ar
N
−KCl
−KCl
Me
Ar
Me
Me
N
Me
Ar
Sn
Ph
N
Me3Si
Ar
Me
Ar
N
Me
N
Sn Ph
Ph
Sn
Me
N
HN
N
Me
Ar
Ar
Me
3, 90%
Ar
4, 70%
5, 20%
Scheme 1. (Ar = C6H3Pri2-2,6).
is unprecedented in being mononuclear and possessing an
exocyclic metallomethyl substituent at an -carbon atom. There
are earlier examples of products resulting from deprotonation of
a methyl group attached to the -carbon atom of a b-diketiminate.
However they relate either to a binuclear complex having a CH2-M
or a ( -CH2)2 moiety as in A [6], or B [7]; or are derived from a
dianionic ligand C, as in [Ge(C)(H)B(H)( -H)2Li(OEt2)3] [8], [Ti(C)
(NC6H3Pri2-2,6)(OEt2)] [9], [Tm(L)(C)] [10], [Si(C)] [11], [Ge(C)]
[12], [Si(C)( [13], [Si(C)(H)(C=CH)] [13],
2-CH@CH)]
[Y(C)2K(dme)2] [14] and [La(C)2K(thf)4]1 [15].
a
N
N
a
NH
Sn
N
l
Sn
l
j
D
D'
Et
Et
Pri
Ca
Pri
thf
Et2N
R2N
Sc
N
Pri
Me
N
Pri
Me
Et
Pri
H2C
Me
Pri
Pri
N
Ca
N
N
N
N
N
N
Pri
Me
Sc
Pri
N
N
N
thf
Pri
Me
NR2
NEt2
Pri
Pri
Et
C [8-15]
A [6]
B [7]
The formation of
4
rather than the expected N-substituted
2.2. The molecular structures of the crystalline complexes 3, 4 and 5
Sn(L)Ph3 is explained by the significant steric demand of the SnPh3
group, which impedes its approach to a nitrogen atom bearing a
bulky aryl substituent. However, solution 1 may be in equilibrium
The molecular structure of crystalline Si(L)Me3 (3) is illustrated
in Fig. 1 and selected geometrical parameters are listed in Table 1.
A zig-zag arrangement of the atoms N1, C1, C2, C3 and N2 is its
core with mutually trans-methyl substituents at C1 and C3 and
an SiMe3 group cisoid to the latter. The CN and CC bond lengths
are consistent with C1–N1 and C3–C2 being double and C1–C2
and N2–C3 being single bonds. The sum of the angles subtended
at each of the three-coordinate atoms C1, C3 and N2 is 360 1°.
The dihedral angle between the N1C1C2 and C2C3N2 planes is
7.44°.
with
a
minute concentration of its tautomer HN(Ar)-
C(Me)C(H)C(@NAr)CH2ꢀK+, which with Ph3SnCl yields 4 with
elimination of KCl.
The formation of 4 from 1 and Ph3SnCl may also be contrasted
with the corresponding reaction of 1 with Me3SnCl in toluene,
which led in low yield to the crystalline compound 5, characterised
solely by its X-ray molecular structure (Section 2.2).
Compound 5 has the Me2Sn moiety bound to the N,C-chelating
dianionic ligand N(Ar)C(Me)C(H)C{N(Ar)}CH2; 5 is dinuclear, the
exocyclic nitrogen atom of each monomeric fragment being coordi-
nated to the tin atom of its neighbouring ‘‘monomer”. A possible
intermediate is either D or D’ which, upon elimination of methane,
yields the monomeric fragment of dimer 5. The reaction leading to 5
may also be contrasted with that in which K[{N(SiMe3)C(Ph)}2CH]
(ꢁ KL00) with 2 equiv. of Me3SnCl gave SnCl(L00)Me2, with
SnMe4 + KCl as supposed co-products [16].
The
molecular
structure
of
crystalline
[(Ar)N(H)C
(Me)C(H)C(CH2SnPh3)N(Ar)] (4) is shown in Fig. 2; selected values
for bond lengths and angles are given in Table 2. The framework
atoms N1, C20, C21, C22 and N2 have a conformation similar to
that in its precursor K(L), but 4 has alternating double (N1–C20
and C21–C22) and single (C20–C21 and C22–N2) bonds. Each of
the C20 and C22 atoms is in an only slightly distorted trigonal pla-
nar environment. The three angles C20–N1–C24, C20–C21–C22

D.J. Doyle et al. / Journal of Organometallic Chemistry 694 (2009) 2611–2617
2613
Table 2
Selected bond lengths (Å) and angles (°) for 4.
Bond lengths
N1–C20
N2–C22
C20–C21
C21–C22
C22–C23
1.308(6)
1.335(6)
1.426(7)
1.369(7)
1.508(7)
C19–Sn
N2–C36
N1–C24
C20–C19
2.174(5)
1.441(6)
1.428(6)
1.505(7)
Bond angles
C20–N1–C24
C22–N2–C36
N1–C20–C21
N2–C22–C21
C20–C21–C22
122.2(4)
127.0(4)
121.1(4)
121.3(5)
126.2(5)
C19–C20–C21
C23–C22–C21
C20–C19–Sn
N1–C20–C19
N2–C22–C23
115.5(4)
120.5(5)
113.0(3)
123.5(4)
118.2(5)
Fig. 1. The molecular structure of crystalline 3 with atom labelling scheme.
Table 1
Selected bond lengths (Å) and angles (°) for 3.
Bond lengths
N1–C1
N2–C3
C1–C2
C2–C3
N2–Si
1.284(3)
1.397(3)
1.462(3)
1.351(3)
1.7788(17)
N1–C6
N2–C18
C3–C5
C1–C4
1.417(2)
1.450(3)
1.497(3)
1.511(3)
Bond angles
C1–N1–C6
C3–N2–C18
N1–C1–C2
N2–C3–C2
C3–N2–Si
120.73(17)
116.72(16)
123.55(19)
121.62(18)
126.44(14)
116.75(12)
N1–C1–C4
N2–C3–C5
C1–C2–C3
C2–C3–C5
C2–C1–C4
123.13(19)
116.44(18)
128.80(19)
121.93(19)
113.25(18)
C18–N2–Si
Fig. 3. An ORTEP representation of the molecular structure of the crystalline
compound 5 with atom labelling scheme (the second independent molecule of 5
and the solvate molecules are omitted for clarity).
Table 3
Selected bond lengths (Å) and angles (°) for 5.
Bond lengths
N1–C1
N2–C3
C1–C2
C2–C3
C1–C4
C3–C17
1.345(9)
1.330(9)
1.395(10)
1.424(10)
1.504(10)
1.503(9)
N1–C5
N2–C18
Sn–N1
Sn–N20
Sn–C17
Sn–C30
Sn–C31
1.459(9)
1.447(9)
2.335(6)
2.387(6)
2.130(6)
2.133(7)
2.142(7)
Bond angles
C1–N1–C5
C3–N2–C18
N1–C1–C2
N2–C3–C2
C1–C2–C3
119.3(6)
119.3(6)
123.1(7)
124.5(6)
128.3(6)
C2–C3–C17
C4–C1–C2
C3–C17–Sn
N1–Sn–N20
N1–Sn–C17
117.8(6)
117.6(6)
111.5(5)
165.5(2)
78.5(2)
0
Symmetry transformations used to generate equivalent atoms: ꢀx + 1, ꢀy + 1,
Fig. 2. The molecular structure of crystalline 4 with atom labelling scheme.
00
ꢀz + 1; ꢀx, ꢀy, ꢀz + 1.
and C22–N2–C36 are within the range 124.5 2.5°. The dihedral
angles between the planes (i) C24–N1–C20 and C19–C20–C21
and (ii) C36–N2–C22 and C22–C21–C20 are 7.99° (i) and 2.95° (ii).
An ORTEP representation of the molecular structure of the crys-
talline, centrosymmetric, dinuclear, fused tricyclic compound
eight-membered puckered SnC17C3N2Sn0C170C30N20 ring is
flanked by the two six-membered rings – SnC17C3C2C1N1 and
its symmetry-related counterpart; the substituents are two methyl
groups at C1 and C10 and a 2,6-Pri2C6H3 group at each of the four
nitrogen atoms. Each of the atoms N1, C1, C3 and N2 is in an only
slightly distorted trigonal planar environment, the endocyclic an-
gles at these atoms being 120.4 3.2°. The C1–C2, C2–C3 and
(5) is shown in Fig. 3, with se-
lected geometrical parameters listed in Table 3. The central

2614
D.J. Doyle et al. / Journal of Organometallic Chemistry 694 (2009) 2611–2617
GeCl4 / O(GeCl3)2
Et2O
Me2SnCl2
C6H14
N
N
N
N
N
N
−LiCl
−LiCl
Ar
Ar
Ar
Ar
Ar
Ar
Ge
Cl
Li
Sn
Cl
O
GeCl3
Me
Cl
thf
thf
Ref. [4]
Me
7, 87%
6, 30%
Scheme 2. (Ar = C6H3Pri2-2,6).
Table 4
C3–N2 bond lengths are indicative of there being some
isation over these four atoms.
p-delocal-
Selected bond lengths (Å) and angles (°) for 6.
Bond lengths
N1–C1
N2–C3
C1–C2
C2–C3
C2–C4
Ge1–O
Ge2–O
1.341(12)
1.298(12)
1.393(13)
1.419(13)
1.465(14)
1.795(7)
N1–C10
N2–C22
N2–Ge1
N1–Ge1
Ge1–Cl1
Ge1–Cl2
Ge2–Cl5
1.471(11)
1.466(11)
2.026(8)
1.910(7)
2.254(3)
2.150(3)
2.108(3)
2.3. Synthesis and structures of the b-dialdiminato–group 14 metal(IV)
complexes 6 and 7
The preparation of the crystalline group 14 metal(IV) deriva-
tives 6 and 7 is summarised in Scheme 2. As far as we are aware,
these are the first heavier group 14 b-dialdiminates, and 6 is the
first monosubstituted derivative of bis(trichlorogermyl) oxide. An
analogue of 7, the crystalline, X-ray-characterised compound
[SnCl(L00)Me2], was previously obtained either from SnCl2Me2 and
Li(L00) or from SnClMe3 and K(L00) [L00 = {N(SiMe3)C(Ph)2}2CH] [16].
The reaction of equimolar portions of [Li(L0)(thf)2] [4] and tetra-
chlorogermane in diethyl ether unexpectedly afforded the high
melting complex [GeCl2(L0)OGeCl3] (6) in moderate yield. The unu-
sual outcome may be explained by the presence of bis(trichloro-
germyl) oxide due to adventitious hydrolysis. Compound 6 was
characterised by satisfactory microanalysis, 1H and 13C{1H} NMR
spectra in C6D6, and a single crystal X-ray diffraction study.
The molecular structure of the crystalline [GeCl2(L0)OGeCl3] (6)
is shown in Fig. 4; selected structural data are given in Table 4. Its
core is a boat-shaped ring, having the Ge1 and C2 atoms 0.569 and
0.112 Å, respectively, out of the N1C1C3N2 plane. Although the
1.704(7)
Bond angles
C1–N1–C10
C3–N2–C22
N1–C1–C2
N2–C3–C2
C1–C2–C3
N1–Ge1–O
N2–Ge1–O
114.4(8)
113.2(7)
129.3(9)
125.9(8)
118.9(9)
135.6(4)
82.5(3)
C1–C2–C4
C3–C2–C4
119.2(9)
120.7(8)
122.7(6)
121.8(1)
89.4(3)
C22–N2–Ge1
C10–N1–Ge1
N1–Ge1–N2
Ge1–O–Ge2
O–Ge2–Cl5
135.3(4)
116.1(3)
endocyclic bond lengths indicate that there is substantial
p-delo-
calisation over the N1C1C2C3N2 moiety, the pairs of bond lengths
Ge1–N1/Ge1–N2, N1–C1/N2–C3 and C1–C2/C2–C3 differ by ca.
0.15, 0.05 and 0.03 Å, respectively. Likewise, the endocyclic bond
angles subtended at the pairs N1/N2 and C1/C3 differ by ca. 1°
Fig. 5. The molecular structure of crystalline 7 with atom labelling scheme.
Table 5
Selected bond lengths (Å) and angles (°) for 7.
Bond lengths
N1–C1
N2–C3
C1–C2
C2–C3
C2–C4
Sn–C34
1.334(4)
1.301(4)
1.389(4)
1.421(4)
1.489(4)
2.127(3)
N1–C10
N2–C22
N2–Sn
N1–Sn
Sn–Cl
1.456(4)
1.451(4)
2.329(2)
2.148(2)
2.5051(8)
2.121(3)
Sn–C35
Bond angles
C1–N1–C10
C3–N2–C22
N1–C1–C2
N2–C3–C2
C1–C2–C3
N1–Sn–Cl
N2–Sn–Cl
114.3(2)
116.0(2)
130.1(3)
126.5(3)
122.4(3)
90.14(7)
170.67(6)
C1–C2–C4
C3–C2–C4
C22–N2–Sn
C10–N1–Sn
N1–Sn–N2
N1–Sn–C35
N2–Sn–C35
119.3(3)
117.8(2)
124.24(18)
123.76(18)
82.20(8)
117.31(12)
88.49(12)
Fig. 4. The molecular structure of crystalline 6 with atom labelling scheme (solvate
molecule is omitted for clarity).

D.J. Doyle et al. / Journal of Organometallic Chemistry 694 (2009) 2611–2617
2615
Table 6
and >3°, respectively. The Ge1–Cl1 and Ge1–Cl2 bond lengths are
Selected bond lengths (Å) and angles (°) for 8.
significantly longer than each of the Ge2–Cl bond lengths, which
range from 2.101(4) to 2.116(3) Å. The five-coordinate Ge1 atom
is in a distorted trigonal bipyramidal environment, the Cl1 and
N2 atoms occupying pseudo-axial positions. The Ge1–O–Ge2 angle
is considerably wider than an sp2 value, consistent with the notion
Bond lengths
Sn–N1
Sn–N2
Sn–Cl
C2–C4
N1–C10
2.190(2)
2.182(2)
2.457(1)
1.487(4)
1.455(3)
N1–C1
N2–C3
C1–C2
C2–C3
N2–C22
1.316(4)
1.324(4)
1.401(4)
1.401(4)
1.447(3)
that the Ge2–O bond has some
p-character, being much shorter
than the Ge1–O bond. Each of the atoms N1, C2 and N2 is close
to being in a distorted trigonal planar environment.
Bond angles
N1–Sn–N2
N1–Sn–Cl
N2–Sn–Cl
N1–C1–C2
N2–C3–C2
C1–C2–C4
C3–C2–C4
84.50(8)
92.75(7)
92.82(7)
128.0(3)
128.2(3)
118.8(3)
116.7(2)
Sn–N1–C1
Sn–N2–C3
C1–C2–C3
Sn–N1–C10
Sn–N2–C22
C1–N1–C10
C3–N2–C22
125.15(18)
125.18(18)
123.6(3)
118.12(16)
118.68(17)
116.5(2)
The molecular structure of the crystalline [SnCl(L0)Me2] (7) is
illustrated in Fig. 5; selected geometrical parameters are listed in
Table 5. The core boat-shaped ring is very similar to that in 6, hav-
ing the atoms Sn and C2 0.933 and 0.166 Å out of the N1C1C3N2
plane. The difference in lengths between the pairs of endocyclic
115.7(2)
bonds at the metal, nitrogen and
a-carbon atoms is ca. 0.18, 0.03
and 0.03 Å, respectively. The corresponding angles at N1 and N2
are almost identical at 119.65 0.15°, but that at C1 is significantly
wider than that at C3. Each of the atoms C2 and N2 is close to being
in a distorted trigonal planar environment, but N1 deviates from
this to some extent. The dihedral angle between (i) the C3–N2–
C22 and the C3–N2–Sn, (ii) the C1–N1–C10 and the C1–N1–Sn
and (iii) the C4–C2–C1 and the C4–C2–C3 planes is 0.73° (i),
17.21° (ii) and 7.48° (iii) respectively. The corresponding values
in 6 with Ge1 in place of Sn are 0.02° (i), 9.42° (ii) and 12.17°
(iii) respectively.
One reason for choosing to prepare 8 was as a potential precur-
sor to a dimeric tin(I) compound L0Sn–SnL0, having noted that two
N,N0-chelated Ge(I) compounds [Ge{(N(C6H3Pri2-2,6))2CR}]2
(R = But or NPri2) had been obtained from the appropriate germa-
nium(II) chloride and potassium [19]. In the event, treatment of
8 with Na/K alloy or KC8 invariably afforded metallic tin.
Analogues of 8 are the crystalline compounds (i) [Sn(Cl)(L)] (E)
[17,18], (ii) [Sn(Cl)(L00)] [20] and (iii) [Sn(Cl)(L000)] [21] obtained
from SnCl2 and the appropriate Li b-diketiminate in diethyl ether
[L000 = {N(C6H2Me3-2,4,6)C(Me)}2CH].
2.4. Synthesis and structure of the b-dialdiminatotin(II) chloride 8
The molecular structure of crystalline [Sn(Cl)(L0)] (8) is shown
in Fig. 6 and selected geometrical parameters are listed in Table
6. The core is a boat-shaped ring having the Sn and C2 atoms out
of the N1C1C3N2 plane by 0.48 and 0.085 Å, respectively. The dihe-
dral angle between that plane and the C1C2C3 or N1SnN2 plane is
The crystalline, high melting compound 8 was prepared as
shown in Eq. (1). It was characterised by C, H and N microanalytical
data, appropriate 1H and 13C NMR spectra in C6D6 and showed the
parent molecular ion as the highest m/e signal in its EI-mass
spectrum.
thf
K[{N(C6H3Pri2-2,6)C(H)}2CPh]
KCl
+
ð1Þ
SnCl2
+
N
N
C6H3Pri2-2,6
8, 48%
2,6-Pri2C6H3
Sn
Cl
7.4(3)° or 17.3(1)°, respectively. The endocyclic bond lengths dem-
onstrate that there is significant -delocalisation in the
p
N1C1C2C3N2 moiety. The fragment ClSn(N1)N2 in 8 is very similar
to that in E: the latter having Sn–N1, Sn–N2 and Sn–Cl bond
lengths of 2.185(2), 2.180(2) and 2.473(9) Å, respectively; and
N1–Sn–N2, N1–Sn–Cl and N2–Sn–Cl bond angles of 85.21(8)°,
90.97(6)° and 93.47°, respectively [18].
3. Experimental
3.1. General details
Syntheses were carried out under an atmosphere of argon or in
vacuum, using Schlenk apparatus and vacuum line techniques. The
solvents employed were reagent grade or better and were freshly
distilled under dry nitrogen gas and freeze/thaw degassed prior
to use. The drying agents were sodium benzophenone (PhMe,
Et2O) or sodium potassium alloy (C5H12, C6H14). The C6D6 for
NMR spectroscopy was stored over molecular sieves (A4). Elemen-
tal analyses were provided by the University of North London.
Melting points were taken in sealed capillaries. The 1H, 13C and
Fig. 6. The molecular structure of crystalline 8 with atom labelling scheme.

2616
D.J. Doyle et al. / Journal of Organometallic Chemistry 694 (2009) 2611–2617
119Sn NMR spectra were recorded in C6D6 at ambient temperature
using a Bruker DPX 300 instrument and were referenced internally
(1H, 13C) to residual solvent resonances or externally (119Sn, with
SnMe4 as standard). Electron impact mass spectra were taken from
solid samples, using a Kratos MS 80RF instrument. IR spectra were
measured on a Perkin Elmer 1720 FT spectrometer, as ‘‘Nujol”
mulls. The compounds Li[{N(C6H3Pri2-2,6)C(Me)}2CH](OEt2) [5]
and Li[{N(C6H3Pri2-2,6)C(H)}2CPh](thf)2 [4] were prepared by pub-
lished procedures. Other starting materials were purchased (Aldrich)
and were rigorously dried before use.
0 °C. The mixture was stirred for 24 h at 25 °C, then filtered. The
volatiles were removed from the filtrate in vacuo. The residue
was extracted into hexane (20 mL). Concentration of this extract
to ca. 10 mL yielded, after cooling at ꢀ15 °C for 24 h, colourless
crystals of 4 (2.26 g, 70%), mp 54 °C, 1H NMR: d 1.08 [d, 6H,
3J(1H–1H) 6.83, CHMe2], 1.09 [d, 6H, 3J(1H–1H) 6.83, CHMe2], 1.15
[d, 6H, 3J(1H–1H) 6.83, CHMe2], 1.26 [d, 6H, 3J(1H–1H) 6.83, CHMe2],
1.46 (s, 3H, NCMe), 2.71 [s, with 119Sn satellites, 2J(119Sn–1H) = 34,
2H, CH2Sn], 3.23 [septet, 2H, 3J(1H–1H) 6.83, CHMe2], 3.38 [septet,
2H, 3J(1H–1H) 6.83 Hz, CHMe2], 5.14 (s, 1H, CHmiddle), 7.16 (m, 15 H,
C6H3Pri2 + m- and p-CH of Ph), 7.55 (m, 6H, o-CH of Ph), 12.4 ppm
(s, 1H, NH); 13C{1H} NMR: d 20.2 (CH2Sn), 23.65 (Pri), 24.6 (Pri),
24.8 (Pri), 28.5 (NCMe); 100.8 (Cmiddle); 123.65, 124.8, 126.8,
127.8, 137.4, 139.0, 141.1, 144.75 (C6H3Pri2 + Ph), 158.8 (CCH2Sn),
165.9 ppm (NCMe).
3.2. Preparation of K[{N(C6H3Pri2-2,6)C(Me)}2CH] (1)
Potassium tert-butoxide (2.76 g, 0.023 mol) was added slowly
with stirring to a solution of Li[{N(C6H3Pri2-2,6)C(Me)}2CH](OEt2)
(12.58 g, 0.023 mol) in hexane (30 mL) at 0 °C. The mixture was
stirred for 12 h at 25 °C, then filtered. The colourless precipitate
of K(L) (1) (8.93 g, 85%) was washed with hexane (4 ꢂ 50 mL)
and dried in vacuo. 1H NMR: d 1.23 (d, 12H, CHMe2), 1.27 (d,
12H, CHMe2), 1.89 (s, 6H, NCMe), 3.34 (septet, 4H, CHMe2), 4.71
(s, 1H, CHmiddle), 7.07–7.16 ppm (m, 6H, C6H3Pri2); 13C{1H} NMR:
d 23.4 (Pri), 23.7 (Pri), 24.45 (Pri), 27.7 (NCMe), 91.3 (Cmiddle);
121.3, 123.55, 123.6, 139.6, 142.75, 150.8 (C6H3Pri2), 161.7 ppm
(NCMe).
3.6. Preparation of
(5)
Trimethyltin chloride (0.44 g, 2.2 mmol) was added to a solu-
tion of K(L) (1) (1.13 g, 2.5 mmol) in diethyl ether (20 mL) at
0 °C. The mixture was stirred for 24 h at 25 °C, then filtered. The
volatiles were removed from the filtrate in vacuo. The residue
was extracted into hexane (ca. 20 mL). Concentration of this ex-
tract to ca. 10 mL yielded, after cooling at ꢀ25 °C for 3 weeks, yel-
low crystals of 5 (0.30 g, 20%). Recrystallisation from toluene
afforded X-ray quality crystals.
3.3. Preparation of {N(C6H3Pri2-2,6)C(Me)}2C(H)C(O)But (2)
3.7. Preparation of Ge(Cl)3OGe(Cl)2[{N(C6H3Pri2-2,6)C(H)}2CPh] (6)
Pivaloyl chloride (0.34 mL, 2.75 mmol) was added slowly to a
solution of K(L) (1) (1.26 g, 2.75 mmol) in toluene (30 mL) at
0 °C. The mixture was stirred for 24 h at 25 °C, then filtered. The
volatiles were removed from the filtrate in vacuo. The residue
was extracted into hexane (50 mL). Concentration of this extract
to ca. 20 mL yielded, after cooling at ꢀ25 °C for 2 d, colourless crys-
talline 2 (1.23 g, 89%). 1H NMR: d 1.15 [d, 6H, 3J(1H–1H) 6.95,
CHMe2], 1.17 (s, 9H, But), 1.18 [d, 6H, 3J(1H–1H) 6.95, CHMe2],
1.21 [d, 6H, 3J(1H–1H) 6.95, CHMe2], 1.22 [d, 6H, 3J(1H–1H)
6.95 Hz, CHMe2], 1.73 (s, 6H, NCMe), 2.97 [septet, 2H, 3J(1H–1H)
6.95, CHMe2], 3.14 [septet, 2H, 3J(1H–1H) 6.95 Hz, CHMe2], 5.24
(s, 1H, CHmiddle), 7.07–7.18 ppm (m, 6H, C6H3Pri2); 13C{1H} NMR: d
20.1 (NCMe), 23.4, 23.5, 23.9 and 24.3 (CHMe2); 26.5 (CMe3), 28.0
and 28.1 (CHMe2); 45.8 (CMe3), 68.6 (Cmiddle); 123.3 and 123.4 (m-
C); 124.4 (p-C), 136.3 and 136.5 (o-C); 146.0 (ipso-C), 167.8 (NCMe),
209.6 ppm (C@O). IR: mmax (cmꢀ1): 1646 (C@N), 1703 (C@O).
[Li(L’)(thf)2] (0.50 g, 0.81 mmol) was added to tetrachloroger-
mane (0.17 g, 0.81 mmol) in diethyl ether (30 mL) at 0 °C. The mix-
ture was stirred for 12 h at 25 °C, then filtered. The volatiles were
removed from the filtrate in vacuo. The residue was extracted into
hexane (30 mL). Concentration of the extract to ca. 15 mL yielded,
after cooling at 25 °C for 2 h, colourless crystals of 6 (0.19 g, 30%),
mp 198 °C. Anal. Calc. for C33H41Cl5Ge2N2O: C, 49.3; H, 5.14; N,
3.48. Found: C, 49.5; H, 5.21; N 3.46%. 1H NMR: d 1.19 [d, 12H,
3J(1H–1H) 6.83, CHMe2], 1.21 [d, 12H, 3J(1H–1H) 6.83, CHMe2],
3.45 [septet, 4H, 3J(1H–1H) 6.83 Hz, CH(CH3)2], 7.10–7.25 [m,
11H, C6H3Pri2 + Ph], 7.77 ppm (s, 2H, NCH); 13C{1H} NMR: d 23.9
(Pri), 28.7 (Pri), 106.5, C(Ph); 123.7, 125.15, 125.4, 126.05, 129.05,
140.4, 141.9, 143.9 (C6H3Pri2 + Ph), 155.8 ppm (NCH).
3.8. Preparation of SnCl(Me)2[{N(C6H3Pri2-2,6)C(H)}2CPh] (7)
i
3.4. Preparation of N(C6H3Pri2-2,6)C(Me)C(H)C(Me)N(C6H3Pr2 -
2,6)SiMe3 (3)
[Li(L’)(thf)2] (0.64 g, 1.00 mmol) was added to dimethyltin
dichloride (0.26 g, 1.18 mmol) in hexane (30 mL) at 0 °C. The mix-
ture was stirred for 12 h at 25 °C, then filtered. The filtrate was
concentrated to ca. 10 mL which, after 12 h at ꢀ25 °C, yielded yel-
low X-ray quality crystals of 7 (0.59 g, 87%), mp 103 °C. EI-MS
(70 eV) m/z (%, assignment): 650 (5, [M]+), 635 (35, [MꢀMe]+),
615 (10, [MꢀCl]+), 585 (20, [Mꢀ2MeꢀCl]+), 466 ([L0H]+, 100). 1H
NMR: d 1.11 (s, 6H, SnMe2), 1.16 [d, 12H, 3J(1H–1H) 6.95, CHMe2],
1.38 [d, 12H, 3J(1H–1H) 6.95, CHMe2], 3.39 [septet, 4H, 3J(1H–1H)
6.95 Hz, CHMe2], 7.00–7.40 (m, 11H, C6H3Pri2 + Ph), 7.70 ppm (s,
2H, NCH); 13C{1H} NMR: d 7.38 (SnMe2), 23.4 (Pri), 23.8 (Pri),
25.5 (Pri), 29.0 (Pri), 101.2 (CPh); 124.2, 125.8, 126.1, 127.35,
129.2, 140.2, 143.6, 146.5 (C6H3Pri2 + Ph), 164.4 ppm [NCH(Ph)];
Chloro(trimethyl)silane (0.36 mL, 2.8 mmol) was added slowly
to a solution of K(L) (1) (1.29 g, 2.8 mmol) in toluene (40 mL) at
0 °C. The mixture was stirred for 24 h at 25 °C, then filtered. The
volatiles were removed from the filtrate in vacuo; the residue
was extracted into hexane (20 mL). Concentration of this extract
to ca. 15 mL yielded, after cooling at ꢀ25 °C for 2 d, colourless crys-
tals of 3 (1.31 g, 90%). 1H NMR: d 0.06 (s, 9H, SiMe3), 1.14 [d, 6H,
3J(1H–1H) 6.83, CHMe2], 1.17 [d, 6H, 3J(1H–1H) 6.83, CHMe2], 1.22
[d, 6H, 3J(1H–1H) 6.83, CHMe2], 1.25 [d, 6H, 3J(1H–1H) 6.83, CHMe2],
1.33 (s, 3H, NCMe), 2.90 (s, 3H, NCMe), 3.03 [septet, 2H, 3J(1H–1H)
6.95 Hz, CHMe2], 3.19 [septet, 2H, 3J(1H–1H) 6.95 Hz, CHMe2], 4.62
(s, 1H, CHmiddle), 7.03–7.19 ppm (m, 6H, C6H3Pri2).
119Sn{1H} NMR:
d
183.8 ppm; 119Sn NMR: 183.8 ppm [spt,
2J(119Sn–1H) 37 Hz].
3.5. Preparation of (C6H3Pri2-
2,6)N(H)C(Me)C(H)C(CH2SnPh3)NC6H3Pri2-2,6 (4)
3.9. Preparation of SnCl[{N(C6H3Pri2-2,6)C(H)}2CPh] (8)
Triphenyltin chloride (1.62 g, 4.2 mmol) was added slowly to a
K(L0) (49 mL of a solution in THF, 6.70 mmol) was added to a
solution of K(L) (1) (1.92 g, 4.2 mmol) in diethyl ether (30 mL) at
solution of tin(II) chloride (1.26 g, 6.70 mmol) in THF (30 mL) at

D.J. Doyle et al. / Journal of Organometallic Chemistry 694 (2009) 2611–2617
2617
Table 7
Crystal data and structure refinement for 3, 4, 5, 6, 7 and 8.
Compound
3
4
5
6
7
8
Formula
M
C32H50N2Si
490.83
C47H56N2Sn
767.63
C62H92N4Sn2 ꢃ 4(C7H8)
1499.31
C33H41Cl5Ge2N2O ꢃ (C6H14
)
C35H47ClN2Sn
649.89
C33H41ClN2Sn
619.82
890.28
Crystal system
Space group
a (Å)
b (Å)
c (Å)
Monoclinic
P21/c (No. 14)
12.8574(2)
13.6643(3)
18.8496(4)
90
105.670(1)
90
3188.55(11)
4
Monoclinic
P21 (No. 4)
11.6059(2)
20.5020(3)
8.9658(2)
90
97.294(1)
90
2116.10(7)
2
Monoclinic
P21/n (No. 14)
15.3418(2)
21.5983(3)
24.1733(3)
90
98.082(1)
90
7930.4(2)
4
Monoclinic
P21/c (No. 14)
16.9671(2)
12.4687(2)
20.3478(3)
90
96.589(1)
90
4276.30(11)
4
Monoclinic
P21/n (No. 14)
11.7221(2)
24.6221(3)
11.7804(2)
90
93.888(1)
90
3392.27(9)
4
Triclinic
P1 (No. 2)
ꢀ
11.5242(3)
11.5988(4)
13.4950(4)
90.979(2)
96.756(2)
118.604(2)
1567.10(9)
2
a
(°)
b (°)
(°)
c
U (Å)
Z
Absorption coefficient (mmꢀ1
)
0.09
0.64
0.68
1.75
0.86
0.92
Unique reflections, Rint
5612, 0.062
4159
0.053, 0.133
0.081, 0.154
7195, 0.040
6863
0.037, 0.102
0.040, 0.103
13756, 0.056
9922
0.078, 0.159
0.107, 0.170
7224, 0.064
6516
0.092, 0.236
0.099, 0.239
5876, 0.062
4979
0.035, 0.069
0.047, 0.074
6177, 0.056
5147
0.034, 0.082
0.048, 0.093
Reflections with I > 2
Final R indices [I > 2
R indices (all data) R1, wR2
r
(I)
r
(I)] R1, wR2
0 °C. The resulting mixture was stirred for 48 h at 25 °C, whereafter
volatiles were removed in vacuo. The residue was washed with
hexane (30 mL). The yellow-orange extract was concentrated in va-
cuo to ca. 15 mL which, after 24 h at ꢀ25 °C, furnished yellow-or-
ange crystals of 8 (1.97 g, 48%), mp 179–181 °C. Anal. Calc. for
C33H41ClN2Sn: C, 63.9; H, 6.61; N, 4.52. Found: C, 63.8; H, 6.62; N
4.44%. 1H NMR: d 1.03 [d, 6H, 3J(1H–1H) 6.6, CHMe2], 1.14 [d, 6H,
3J(1H–1H) 6.6, CHMe2], 1.23 [d, 6H, 3J(1H–1H), CHMe2], 1.41 [d,
6H, 3J(1H–1H) 6.6, CHMe2], 3.24 [septet, 2H, 3J(1H–1H) 6.6, CHMe2],
4.21 [septet, 2H, 3J(1H–1H) 6.6 Hz, CHMe2], 7.00–7.21 (m, br, 11H,
C6H3Pri2 + Ph), 7.74 ppm [s, with 119Sn satellites, 3J(119Sn–1H) =
19 Hz, 2H, NCH]; 13C{1H} NMR: d 23.4, 25.2, 25.3, 25.6 (CHMe2)
28.2, 29.8 (CHMe2); 110.5 (CPh);123.6, 125.7, 125.8, 126.7, 127.8,
129.2, 140.6, 142.8, 144.6, 145.3 (C6H3Pri2 + Ph); 158.9 ppm
[NCH(Ph)]. EI-MS: m/z (%, assignment): 619 (36, [Mꢀ1]+), 584
(55, [MꢀClꢀ1]+), 466 (100, [L0H]+).
Appendix A. Supplementary material
CCDC 721035, 721036, 721037, 721038, 721039 and 721040
contain the supplementary crystallographic data for this paper.
These data can be obtained free of charge from The Cambridge Crys-
tallographic Data Centre via www.ccdc.cam.ac.uk/data_request/cif.
Supplementary data associated with this article can be found, in the
online version, at doi:10.1016/j.jorganchem.2009.03.044.
References
[1] L. Bourget-Merle, M.F. Lappert, J.R. Severn, Chem. Rev. 102 (2002) 3031.
[2] D.J.E. Spencer, N.W. Aboelella, A.M. Reynolds, P.L. Holland, W.B. Tolman, J. Am.
Chem. Soc. 124 (2002) 2108.
[3] Y. Cheng, P.B. Hitchcock, M.F. Lappert, M. Zhou, Chem. Commun. (2005) 752.
[4] Y. Cheng, D.J. Doyle, P.B. Hitchcock, M.F. Lappert, Dalton Trans. (2006) 4449.
[5] M. Stender, R.J. Wright, B.E. Eichler, J. Prust, M.M. Olmstead, H.W. Roesky, P.P.
Power, J. Chem. Soc., Dalton Trans. (2001) 3456.
[6] A.M. Neculai, H.W. Roesky, D. Neculai, J. Magull, Organometallics 20 (2001)
5501.
[7] J. Harder, Angew. Chem., Int. Ed. 42 (2003) 3430.
[8] Y. Ding, H. Hao, H.W. Roesky, M. Noltemeyer, H.-G. Schmidt, Organometallics
20 (2001) 4806.
[9] F. Basuli, J.C. Huffman, D.J. Mindiola, Inorg. Chem. 42 (2003) 8003.
[10] P.B. Hitchcock, M.F. Lappert, A.V. Protchenko, Chem. Commun. (2005) 951.
[11] M. Driess, S. Yao, M. Brym, C. van Wüllen, D. Lentz, J. Am. Chem. Soc. 128
(2006) 9628.
[12] M. Driess, S. Yao, M. Brym, C. van Wüllen, Angew. Chem., Int. Ed. 45 (2006)
6730.
[13] S. Yao, C. van Wüllen, M. Driess, Chem. Commun. (2008) 5393.
[14] S.T. Liddle, P.L. Arnold, Dalton Trans. (2007) 3305.
[15] S. Bambirra, F. Perazzolo, S.J. Boot, T.J.J. Sciarone, A. Meetsma, B. Hessen,
Organometallics 27 (2008) 704.
[16] P.B. Hitchcock, M.F. Lappert, D.-S. Liu, J. Chem. Soc., Chem. Commun. (1994)
1699.
3.10. X-ray crystallographic studies for 3, 4, 5, 6, 7 and 8
Diffraction data were collected on a Nonius Kappa CCD diffrac-
tometer using monochromated Mo Ka radiation, k 0.71073 Å at
173(2) K. Crystals were coated in oil and then directly mounted
on the diffractometer under a stream of cold nitrogen gas. The
structures were refined on all F2 using SHELXL-97 [22]; absorption
corrections for 4, 5, 6, 7 and 8 were applied using MULTISCAN.
Drawings used ORTEP-3 for Windows. For 5, there were two indepen-
dent dimers, both lying on an inversion centre. There were also
four independent toluene solvate molecules all included with C6
rings as rigid bodies and with isotropic C atoms. Further details
are given in Table 7.
[17] A.P. Dove, V.C. Gibson, E.L. Marshall, A.J.P. White, D.J. Williams, Chem.
Commun. (2001) 283.
[18] Y. Ding, H.W. Roesky, M. Noltemeyer, H.-G. Schmidt, P.P. Power,
Organometallics 20 (2001) 1190.
[19] S.P. Green, C. Jones, P.C. Junk, K.-A. Lippert, A. Stasch, Chem. Commun. (2006)
3978.
Acknowledgements
[20] P.B. Hitchcock, M.F. Lappert, J.R. Severn, Dalton Trans. (2004) 4193.
[21] A.E. Ayers, T.M. Klapötke, H.R.V. Dias, Inorg. Chem. 40 (2001) 1000.
ˇ ˇ
We thank Drs. A.V. Khvostov, A.V. Protchenko and A. Ru˚ zicka for
helpful advice, and the Royal Society for the award of a Sino-British
Fellowship to G.L.
[22] G.M. Sheldrick, SHELX-97
, Program for Refinement of Crystal Structures,
University of Göttingen, Germany, 1997.