Synthesis and structure of new compounds with Pt-Ga bonds: Insertion of the bulky gallium (I) bisimidinate Ga(DDP) into Pt-Cl bond

Article abstract of DOI:10.1016/j.jorganchem.2011.04.008

Reactions of the sterically bulky mono-valent group 13 bisimidinate gallium(I), Ga(DDP) (1) (DDP = 2-{(2, 6-diisopropylphenyl)amino}-4-{(2, 6-diisopropylphenyl)imino}-2-pentene, HC(CMeNC₆H₃-2,6- ⁱPr₂)₂) with olefin supported group 10 complexes, [(diene)PtCl₂] [diene = 1,5-cyclooctadiene (COD), endo-dicyclopentadiene (dcy)] and [(COD)Pd(Me)(OTf)] (OTf = O ₃SCF₃) are reported. These reactions afforded [(COD)Pt(Cl){ClGa(DDP)}] (2), [(dcy)Pt(Cl){ClGa(DDP)}] (3) and [(DDP)Ga(Me)(OTf)] (4) in moderate yields. Compounds 2-4 were characterized by elemental analysis, NMR (¹H, ¹³C) spectroscopy and also by single crystal X-ray structural analysis. The solid state structures of complexes 2 and 3 reveal the oxidative insertion of Ga(DDP) into the Pt-Cl bond without altering the π-coordinated double bonds in the olefin.

Full text of DOI:10.1016/j.jorganchem.2011.04.008

Journal of Organometallic Chemistry 696 (2011) 2635e2640
Contents lists available at ScienceDirect
Journal of Organometallic Chemistry
journal homepage: www.elsevier.com/locate/jorganchem
Synthesis and structure of new compounds with PteGa bonds: Insertion
of the bulky gallium (I) bisimidinate Ga(DDP) into PteCl bond
,
Adinarayana Doddi a, Christian Gemel a, Rüdiger W. Seidel b, Manuela Winter a, Roland A. Fischer a
*
a Inorganic Chemistry-II, Organometallics and Materials, Faculty of Chemistry and Biochemistry, Ruhr University Bochum, Universtitaetsstrasse 150, D-44780 Bochum, Germany
b Analytical Chemistry, Faculty of Chemistry and Biochemistry, Ruhr University Bochum, D-44780 Bochum, Germany
a r t i c l e i n f o
a b s t r a c t
Article history:
Reactions of the sterically bulky mono-valent group 13 bisimidinate gallium(I), Ga(DDP) (1) (DDP ¼ 2-
Received 22 February 2011
Received in revised form
5 April 2011
{(2,
6-diisopropylphenyl)amino}-4-{(2,
6-diisopropylphenyl)imino}-2-pentene,
HC(CMeNC6H3-
2,6-iPr2)2) with olefin supported group 10 complexes, [(diene)PtCl2] [diene ¼ 1,5-cyclooctadiene (COD),
endo-dicyclopentadiene (dcy)] and [(COD)Pd(Me)(OTf)] (OTf ¼ O3SCF3) are reported. These reactions
afforded [(COD)Pt(Cl){ClGa(DDP)}] (2), [(dcy)Pt(Cl){ClGa(DDP)}] (3) and [(DDP)Ga(Me)(OTf)] (4) in
moderate yields. Compounds 2e4 were characterized by elemental analysis, NMR (1H, 13C) spectroscopy
and also by single crystal X-ray structural analysis. The solid state structures of complexes 2 and 3 reveal
Accepted 8 April 2011
Keywords:
Insertion
Cyclooctadiene
Platinum complexes
Dicylcopentadiene
Main-group
the oxidative insertion of Ga(DDP) into the PteCl bond without altering the
in the olefin.
p-coordinated double bonds
Ó 2011 Elsevier B.V. All rights reserved.
1. Introduction
difference between the behaviour of N-heterocyclic carbenes and
ER ligands. In addition to its coordinating properties, ER ligands
exhibit strong reducing properties and may also yield insertion
compounds as intermediates when combined with compounds
exhibiting MeX bonds. Among these main-group metaleligand
The isolation and structural characterization of low oxidation
state group 13 metal (I) chemical entities at room temperature have
opened up new horizons in the history of main-group chemistry.
The coordination chemistry of these sterically demanding ER type
of compounds (E ¼ Al, Ga, In; R ¼ bulky alkyl, aryl, C5Meꢀ5 , etc.) as
ligands to yield a variety of intermetallic transition metal (M)
complexes of the kind [(LnM)a(ER)b] (a < b) is a continuously
expanding field [1]. Besides fundamental interest in structure and
bonding, the chemistry of these complexes and clusters with
unsupported MeE bonds is related to the materials chemistry of
the respective alloys or intermetallic compounds [1b,d,e]. Early
work in this direction targeted MOCVD of CoGa and related mate-
rials [2a,b], more recent work deals with soft chemical synthesis of
MxEy alloy nanoparticles [2c,e] such as NiAl dispersed as colloids
[2c]. The substitution or the rearrangement of the labile ligands (i.e,
CO, PR3 and olefins) by ER has proven to be the most fruitful
synthetic route for making a variety of such homoleptic and het-
eroleptic complexes [1,3]. Their reactivity and electronic properties
are comparable with the well-known N-heterocyclic carbene (NHC)
class of ligands. The NHC analogous ER ligands are thus considered
species, the neutral and bulky six-membered
b-diketiminato
i
derivatives [:E{[N(Ar)C(Me)]2CH}; Ar ¼ C6H3 Pr2ꢀ2,6; E ¼ Al [4], Ga
[5], In [6], Tl [7]], abbreviated as E(DDP) [DDP ¼ 2-{(2,6-diisopro-
pylphenyl)amino}-4-{(2,6-diisopropylphenyl)imino}-2-pentene],
are of special interest due to the bulkiness which can be incorpo-
rated into their metal complexes. Another NHC analogous anionic
five-membered diazabutadienido ligand [:Ga{N(R)C(H)}2]L
(R ¼ tBu, Ar) [8] and recently the neutral four-membered guani-
dinate ligands [:E{(Ar)NC(NCy2)N(Ar)}] (E ¼ Ga, In, Tl) [9] have
been developed during the last five years.
The chemistry of platinum gallyl complexes with these gallium
(I) heterocyclic ligands have been explored some extent. Very
recently the first homoleptic platinum(0) complex, [Pt{Ga(Giso)}3]
with the neutral four-membered guanidinato gallium(I) heterocycle
[:Ga(Giso)] (Giso ¼ {(2,6-iPr2C6H3)NC(NCy2)N(C6H3-2,6-iPr2)}, Cy ¼
cylohexyl) was reported by C. Jones and his coworkers, where they
described particularly short PteGa (3-coordinate) bonds [10].
Likewise, few structurally interesting platinum complexes have also
been reported with the anionic gallium (I) heterocyle by the salt
elimination process [11].
as strong s-donors due to the presence of a sp hybridized lone pair
on the main-group metal (I) centre. However, there is a striking
Although the insertion chemistry of Ga(DDP) (1) has been
explored to some extent towards transition and main-group metal
* Corresponding author. Tel.: þ49 (0) 234 32 24174; fax: þ49 (0) 234 32 14174.
E-mail address: roland.fischer@rub.de (R.A. Fischer).
0022-328X/$ e see front matter Ó 2011 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2011.04.008

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A. Doddi et al. / Journal of Organometallic Chemistry 696 (2011) 2635e2640
complexes (Fig. 1) (i.e. the insertion behaviour of Ga(DDP) into the
MeX ( M: Si, Sn, Ga, Hg, Zn, Pb, Rh, Bu, X:eCl, eO3SCF3) and also
15e30 min of stirring at room temperature. This colour gradually
changed to brown as the final colour of the reaction mixture.
Complexes 2 and 3 are stable over several days in their solidestate at
room temperature under inert atmosphere (Ar), but prolonged
storage in solution and solidestate lead to slow decomposition with
formation of a grey substance. They readily dissolve in common
organic solvents such as THF, benzene and toluene but are insoluble
in hexane and pentane. Elemental analysis of both compounds are in
good agreement with the proposed molecular formulae [(COD)Pt(Cl)
{ClGa(DDP)}] (2) and [(dcy)Pt(Cl){ClGa(DDP)}] (3).
To gain further insight into these reactions, we have carried out
some experiments using a two fold excess of Ga(DDP) for the
possibleisolation ofPt(0) complexes, sinceweexpectedthat ligand1
can take up to two Clꢀ ligands from the Pt centre, there by leading to
Cl2Ga(DDP) as an anticipated by-product. However, no other prod-
ucts were isolated, except for 2 and 3 from their respective reactions
according to Scheme 1. It is worth mentioning that our previous
workon the reaction of [Pt(COD)2] with 1 forms a bright orange Pt(0)
complex [Pt(COD){Ga(DDP)}2] in hexane, but in the present case no
such compounds were observed, but only oxidative insertion of
Ga(DDP) into the PteCl bond has occurred [17]. This might be due to
the fact that the steric bulk of 1 normally does not favour more
t
MeC (M: Ga) bonds) [12e16], the same chemistry with olefin sup-
ported platinum(II) chloro complexes is not explored. To the best of
our knowledge, only a very few Ga(DDP) containing platinum
complexes have been reported in the literature so far [17]. Following
our previous work on the reactivity of zero valent, olefin supported
platinum and palladium complexes towards ER [18e23], we got
interested in comparing the reactions of 1 with olefin complexes of
the group 10 metal centres PtII and PdII. Herein, we report the reac-
tions of Ga(DDP) with the olefin supported complexes containing
PteCl and PdeMe bonds, such as [(diene)PtCl2] [diene ¼ 1,5-cyclo-
octadiene, (dcy) endo-dicyclopetadiene] and [(COD)PdMe(OTf)] in
comparison to the reaction of [Pt(COD)2] with Ga(DDP) which yields
a bright orange complex [(1,3-COD)Pt{Ga(DDP)}2] [17].
2. Results and discussion
Unlike GaCp*, GaI(DDP) is less reducing and very bulky and thus
likely not to yield homoleptic complexes [Pt(Ga(DDP)n)] (n ꢁ 4) such
as [Pt{Ga(Giso)}3] [10] or [Pt(GaCp*)4] [22] when combined with the
selectedolefin supportedPt(II)complexes, [(diene)PtCl2 (diene¼ 1,5-
COD, dcy)] and the Pd(II) complex [(1,5-COD)PdMe(OTf)]. These
reactions afforded the new platinum complexes [(COD)Pt(Cl)
{ClGa(DDP)}] (2) and [(dcy)Pt(Cl){ClGa(DDP)}] (3) as the insertion
products of gallium into PteCl bonds, while the palladium(II)
complex is reduced to Pd(0) and [(DDP)Ga(Me)(OTf)] (4) was
obtained as the stoichiometric by-product. All new compounds 2e4
were analytically and structurally characterized, as described in the
following.
substitution at the platinum centre unlike GaCp
*, with which a few
homoleptic and heteroleptic complexes have been isolated [22].
The 1H and 13C NMR spectra of 2 and 3 exhibit the expected
resonances for the DDP ligand. These data is consistent with their
proposed structures. The typical 1H NMR resonances [C6D6 for 2
and d8-THF for 3] for methine (
g-CH) protons of the DDP backbone
in both 2 and 3 are observed as sharp singlets at
d
4.94 and 5.15 ppm
respectively (Supporting Information Figure S2 and S5) which are
in the expected range when compared to the Ga(DDP)-supported
metal complexes [12e15]. The resonance due to the olefin
protons of COD in 2 appears as two different broad multiplets
2.1. Synthesis and characterization of [(COD)Pt(Cl){ClGa(DDP)}] (2)
and [(dcy)Pt(Cl){ClGa(DDP)}] (3)
centred at
195Pt satellites, and whereas the eCHe protons of isopropyl groups
show two different overlapping septets centred at 3.80 and
3.89 ppm. The JPt-H couplings to these olefin protons (10e35 Hz)
are considerably lower than those for [Cl2Pt(COD)] (2JPtꢀH ¼ 65 Hz)
[24]. The 13C NMR chemical shifts found for DDP and COD moieties
d 4.53 and 5.52 ppm, associated with the NMR active
An equimolar mixture of 1 with platinum(II)-olefin complexes
[(1,5-COD)PtCl2] and [(dcy)PtCl2] in toluene at room temperature,
affordedpale yellowcrystals of platinumegallyl complexes in 43% (2)
and 28% (3) yield respectively (Scheme 1). During these reactions, the
initial colour of the reaction mixture (yellow) changed to orange after
d
2
Fig. 1. Examples of main-group and transition metal complexes with insertion of Ga(DDP).

A. Doddi et al. / Journal of Organometallic Chemistry 696 (2011) 2635e2640
2637
Scheme 1. Synthesis of platinumegallyl complexes 2e4 from GaI(DDP).
fall in the expected range (Supporting Information S3). Molecule 3
exhibits a non symmetric structure in solution at room tempera-
ture, which makes all protons magnetically non-equivalent. We
were able to assign all resonances in 3 from the two-dimensional
nuclear magnetic resonance spectroscopy [HMBC (Heteronuclear
Multiple Bond Coherence) spectrum, see Supporting Information
Figure: S7]. The structural complexity in the molecule 3 caused
a few broad, partially overlapping signals of DDP and dicyclo-
pentadienyl ligands in the aliphatic region. The proton NMR spec-
trum of 3 exhibits the characteristic 4 septets of eCHe and 8 sets of
doublets associated with 4 and 8 non-equivalent isopropyl and
methyl protons of this complex, while the 13C NMR spectrum shows
the expected twelve resonances of the corresponding carbons. In
contrast, 1H NMR spectrum of 2 shows only 6 resonances (two
septets and four doublets) for the same protons, indicative of an
over-all more symmetric structure in solution.
concomitant oxidation of group 13 metal GaI to GaIII by abstracting
eCH3 and triflate groups from the palladium centre. It appears that
this reduction is quite fast and yields a black precipitate within few
minutes of reaction time. Compound 4 is sensitive to air and
moisture and soluble in common organic solvents such as benzene,
toluene, fluorobenzene and THF. The 1H NMR spectrum of 4 shows
a sharp singlet at
d 1.57 ppm, corresponding to the presence of
methyl protons of DDP ring. The eCHe protons of isopropyl groups
appear as broad resonances at 2.84 and 3.84 ppm. In addition to the
DDP ligand, the resonance associated with methyl protons of
GaeCH3 appears at
carbon resonates at
The typical methine (
the low field region (
d
; ꢀ0.46 ppm in 1H NMR and that of the methyl
d
; ꢀ13.8 ppm in 13C NMR spectrum [5,25,26].
g
-CH) carbon in DDP ring is slightly shifted to
d
100.7 ppm) due to the presence of triflate
group on the gallium (III) centre. It is noteworthy that the triflate
carbon atom was not observed in the 13C{1H} NMR spectroscopic
time scale, hence the existence of triflate group is confirmed from
the infrared spectrum. A sharp stretching frequency observed at
1013 cm-1 is assigned for the CeF bonds (Supporting Information
Figure S11).
Furthermore, complex 3 exhibits the unequal nature of two CH3
protons on the DDP ring which appear at
NMR of 3 at room temperature also exhibits four different broad
olefin protons centred at 7.88, 6.19, 4.87 and 4.17 ppm, which are
associated to the coupling with 195Pt nuclei. The corresponding 13
NMR chemical shifts are assigned as 139.4 and 132.6 ppm for the
d
1.77 and 1.74 ppm. 1H
d
C
d
olefin carbons of eC3 ¼ C4e and 85.2 and 83.1 for C1]C2 (atom
labelling is shown in Fig. 4, for 13C NMR see Supporting Information
Figure S6). The methine
(g-C12) carbon in 3 resonates at
d
100.4 ppm whereas the same DDP carbon in 2 resonates at
99.4 ppm, which is slightly shifted to up field region. The 13C NMR
spectrum of 3 also indicates the deshielding nature of imino
carbons (eC]Ne) occurred in DDP ring (d 170.9 and 170.7 ppm),
when compared with the literature reported complexes [17]. The
structure and composition of 2 and 3 are consistent with the
elemental, 1H and 13C NMR data.
Fig. 2. Molecular structure of 2. Displacement ellipsoids are drawn at 50% probability
level. Hydrogen atoms and solvent molecules are omitted for clarity. Selected bond
lengths (Å) and angles (deg): Pt(1)eGa(2) 2.417(16), Pt(1)eC(5) 2.155(10), Pt(1)eC(4)
2.211(12), Pt(1)eCl(1) 2.362(3), Pt(1)eC(8) 2.454(13), C(4)eC(5) 1.385(15), C(1)eC(8)
1.389(16), Ga(2)eCl(2) 2.249(3), Ga(2)eN(2) 1.983(10), N(1)eGa(2) 2.019(9), Pt(1)eCl(1)
2.362(3), Cl(1)ePt(1)eGa(2) 85.5(8), Cl(2)eGa(2)ePt(1) 110.0(9), N(2)eGa(2)eN(1)
97.2(4).
2.2. Reaction of [(COD)Pd(Me)(OTf)] with GaI(DDP)
The reaction of 1 with [(COD)Pd(Me)(OTf)] afforded [(DDP)
Ga(Me)(OTf)] (4) as a colourless solid in 33% isolated yield. The
formation of 4 involves the reduction of PdII to Pd0 followed by the

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A. Doddi et al. / Journal of Organometallic Chemistry 696 (2011) 2635e2640
Table 1
Crystallographic data and collection parameters for compounds 2 and 3.a
2
3
Formula
Mol wt
C
44H61 Cl2GaN2Pt
C53H69Cl2GaN2Pt
1069.81
953.66
Data / restraints / parameters
Data coll, T, K
6936 / 120 / 398
111(2)
8538 / 42 / 483
110(2)
Wavelength, Å
0.71073
0.71073
Crystal system, space group
Triclinic, P-1
11.0869(12)
12.4058(11)
15.6409(16)
88.722(8)
79.674(9)
69.390(9)
1979.0(3)
2, 1.600
Monoclinic, P21/c
20.3741(11)
18.3324(10)
12.9208(7)
90.00
90.083(5)
90.00
4826.0(5)
4, 1.472
a, Å
b, Å
c, Å
a
b
g
, deg
, deg
, deg
Fig. 3. Molecular structure of 3. Displacement ellipsoids are drawn at 50% probability
level. Hydrogen atoms and solvent molecules are omitted for clarity. The disorder in
the dcy carbons has been refined. Selected bond lengths (Å) and angles (deg): Pt(1)e
Ga(2) 2.413(7), Pt(1)eC(31) 2.146(11), Pt(1)eC(30) 2.161(11), Pt(1)eC(39), 2.507(12),
Pt(1)eC(38) 2.576(10), Ga(1)eCl(2) 2.214(19), Pt(1)eCl(1) 2.320(2), Ga(1)eN(1)
1.953(5), Ga(1)eN(2) 1.962(6), C(30)eC(31) 1.372(15), C(38)eC(39) 1.459(15), Cl(1)e
Pt(1)eGa(1) 85.3(5), Cl(2)eGa(1)ePt(1) 111.56(6), N(1)eGa(1)eN(2) 96.3(2).
V, A3
Z,
m
r
(Calcd) Mg/m3
, mm-1
4.380
3.601
F(000)
Crystal size, mm
964
2176
0.35 ꢃ 0.30 ꢃ 0.25
3.09 to 25.00
12433 / 6936
[R(int) ¼ 0.1060]
ꢀ13<¼h<¼13,
ꢀ11<¼k<¼14,
ꢀ18<¼l<¼18
99.6%
Empirical
0.4073 and 0.3094
0.683
R1 ¼ 0.0573,
wR2 ¼ 0.0997
R1 ¼ 0.1407,
wR2 ¼ 0.1115
1.934 and -1.426
0.31 ꢃ 0.10 ꢃ 0.07
2.90 to 25.05
70499 /8538
[R(int) ¼ 0.1515]
ꢀ24<¼h<¼24,
ꢀ21<¼k<¼21,
ꢀ15<¼l<¼15
99.8 %
Empirical
0.7866 and 0.4015
0.950
R1 ¼ 0.0544,
wR2 ¼ 0.1099
R1 ¼ 0.0962,
wR2 ¼ 0.1177
0.948 and -1.842
q
range, deg
Reflections collected/unique
2.3. Molecular structures of 2e4
Limiting indices
In order to characterise the platinum-gallium bonding, the solid
state structures of 2 and 3 were unambiguously determined by the
single crystal X-ray diffraction technique. Perspective views of the
molecular structures of 2, 3 with atom numbering schemes are
shown in Figs. 2 and 3 respectively. Crystal data and the details of
the structure determinations are given in Table 1, whereas selected
bond lengths and bond angles are given in corresponding figure
footnotes.
Completeness to theta ¼ 25.00,
Absorption correction
Max. and min. transmission
Goodness-of-fit on F2
Final R indices [I>2sigma(I)]
R indices (all data)
Largest diff. peak and hole, e.Aꢀ3
Single crystals suitable for X-ray structural determination for
compounds 2 and 3 were obtained as pale yellow crystals from
a
refinement method - Full-matrix least-squares on F2
ꢂ
saturated toluene solutions at ꢀ30 C. For compound 4 colourless
crystals were grown from toluene by layering with n-hexane
at ꢀ30 ꢂC. X-ray crystallographic analysis carried out on compound
4 resulted in poor crystallographic data. Therefore, its data and
structure are not included here (see in the supplementary data as
Figure S1 and Table S1). Nevertheless, the data obtained for 4 are
sufficient to get the connectivity of all the atoms, which confirmed
the presence of a tetra-coordinated gallium centre bearing one DDP
ligand and both, the triflate and methyl groups. These data match
with the analytical and spectroscopic characterization of 4.
Complex 2 crystallized in the space group P-1 with a disordered
solvent molecule (toluene), whereas complex 3 crystallized with
two solvent (toluene) molecules in the monoclinic system (Space
group P21/c). The solid state structures of 2 and 3 shows the
insertion of Ga(DDP) into the PteCl bond. The molecular structure
of complexes 2 and 3 depicts that the Pt centres are surrounded by
Cl, Ga(DDP) and
4-coordinated 1,5-cyclooctadiene (for 2) and h4
h
-
coordinated dicyclopentadiene (for 3). In both compounds the Cl
ligands are arranged in a trans orientation to each other. The PteGa
bond distances in 2 and 3 are almost identical [Pt(1)eGa(2)
2.417(2), Pt(1)eGa(2) 2.413(7) Å]. These bonds are considerably
longer than the PteGa distances in the homoleptic complex
[Pt(GaCp*)4] (2.335(2) Å) or the terminal PteGa distances in the
dimeric cluster [Pt2(GaCp*)5] (2.326(2) Å and 2.331(1) Å) [22], both
featuring Ga(I) ligands. A similar trend can be observed when
platinum complexes containing COD and Ga(DDP) are compared,
for example [Pt(1,3-COD){Ga(DDP)}2] (PteGa 2.346(1) and 2.342(1)
Å) [17] and [Pt{Ga{[N(Ar)C(H)2]}}2(COD)] (PteGa 2.383(7) Å) [11].
This elongation is expected because of the tetra-coordinated Ga
centre of 2 (also in 3), as compared with lower coordinate Ga
centres in the cited reference compounds. Certainly, the bulky N-
heterocyclic ligand maintains some steric effect on the PteGa bond
distance, too. One should be aware that this kind of PteGa bond
lengths, and MeE bonds in general are quite dependent on the type
of ligands at both metal centres which influence electronic and
steric situations simultaneously. For example, the PteGa distance of
t
[(Cy2PCH2CH2PCy2)Pt(GaR2)(R)] (R ¼ CH2 Bu, Cy ¼ cyclohexyl),
exhibiting a tri-coordinate Ga centre, amounts to 2.438(1) Å [27].
The PteCl bond distance in complex 2 [2.362(3) Å] shows a notable
deviation when compared to the parent molecule [(1, 5-COD)PtCl2]
(av: PteCl 2.257 Å) [28,29]. As it is observed in other Ga(DDP)
supported metal complexes, the bond angles in both compounds
suggest that the gallium centre is shifted out from the heterocyclic
C3N2 plane after coordination with the platinum centre. The bite
angles of NeGaeN in complexes 2 and 3 are 97.2(4)ꢂ [N(2)-Ga(2)e
N(1)] and 96.3(2)ꢂ [N(1)eGa(1)eN(2)], respectively, which are
significantly larger than the same observed in Ga(DDP) (85.53(5)ꢂ)
Fig. 4. All carbon atoms are labelled for NMR assignment in complex 3.

A. Doddi et al. / Journal of Organometallic Chemistry 696 (2011) 2635e2640
2639
[5]. In complex 2, the change in the bite angle is approximately
11.47ꢂ, whereas in 3, it is 10.77ꢂ which lies in the range of those
compounds previously reported [12d, 15,30]. The GaeN bond
lengths are shortened considerably in comparison with the free
ligand 1. The average GaeN bond distances in 1 is reported as
2.054 Å, whereas the average GaeN bond lengths in 2 and 3 are
observed as 2.001 and 1.957 Å respectively. The increased electro-
philic nature of 1 upon insertion reaction and coordination to the
platinum centre in 2 and 3, has resulted in the shortening of GaeN
bonds and elongation in NeGaeN bite angles relative to the free
Ga(DDP). However, the structural features of the Ga(DDP) backbone
in 2 and 3 are similar to those reported metal complexes containing
this sterically crowded ligand [15]. At this point we like to note that
we refrain from discussing oxidation states of the Ga centres in 2
and 3 for reasons we have extensively explained in numerous
previous publications on similar systems [12d,31].
and then filtered to remove the black solid. The filtrate was
concentrated to half of its volume and stored at ꢀ30 ꢂC for one week
to afford pale yellow needles of 1. These crystals were filtered and
quickly washed with n-hexane (2 ꢃ 2 mL) and dried in vacuo. Yield:
43% (0.05 g, based on [(1,5-COD)PtCl2]). Mp: > 185 ꢂC (decomp). 1H
NMR(C6D6, 250.1 MHz, ppm):
d
¼ 7.16e7.14 (m, 6H, phenyl),
2
5.57e5.47 (m, JPt-H ¼ 10 Hz, 2H, HeC]C, COD), 4.94 (s, 1H, CH,
2
Ga(DDP)), 4.66e4.36 (m, JPt-H ¼ 35 Hz, 2H, HeC]C, COD),
3.94e3.75 ( m, 4H, merged with each other, CH(CH3)2), 1.62 (s, 6H,
CH3), 1.58e1.52 (m, 12H, merged with CH(CH3)2 and 2H from
HeCeC, COD) 1.34e1.27 (m, 4H, HeCeC, COD), 1.23 (d, 2JHH ¼ 7 Hz,
6H, CH(CH3)2), merged with 2H from HeCeC, COD), 1.14 (d,
2JHH ¼ 6.5 Hz, 6H, CH(CH3)2).13C NMR (C6D6, 62.8952 MHz):
¼ 169.6
d
(C]N), 145.3 (C(Dipp)eN), 145.1 (C(Dipp)-N, Dipp ¼ 2, 6-diisopro-
pylphenyl), 142.2 (o-C(Dipp)), 127.3 (m-C(Dipp)), 125.0 (m-C(Dipp)),
124.6 (p-C(Dipp)), 124.3 (p-C(Dipp)), 99.4 (g-C), 77.6 (C]C; COD),
32.1 (CeC, COD], 28.8 (CHMe2), 28.5 (CHMe2), 26.5 (CMe), 25.8
(CMe), 25.2 (CHMe2), 25.1 (CHMe2), 25.0 (CHMe2), 24.1 (CHMe2)ppm.
3. Conclusions
IR (n
, cmꢀ1): 2938(m), 2844(w), 1517(vs), 1449(m), 1424(m),
In summary, we have prepared two new PteGa containing
compounds and showed that Ga(DDP) selectively inserts into the
PteCl bonds of [(1,5-COD)PtCl2] and [(dcy)PtCl2] to yield exclusively
products 2 and 3. Unlike the GaCp*, Ga(DDP) does not reduce the
Pt(II) centre and trap the Pt(0) by substituting the olefin ligands
even when used in excess [17]. In contrast, the reaction of Ga(DDP)
with Pd(II) precursor yields Pd(0) as precipitate and the oxidized
gallium(III) product [(DDP)Ga(Me)(OTf)] (4). This behaviour is in
accordance with the steric bulk of Ga(DDP), which hinders the
efficient trapping of Pd(0) as [Pd(Ga(DDP)n)], the weaker coordi-
nation properties of the hard triflate at the soft Pd in comparison to
Cl and the well-known over-all enhanced susceptibility of organ-
ometallic Pd(II) complexes for reduction to Pd(0) in comparison to
Pt(II). The ambivalent reactivity of Ga(DDP), depending on the
transition metal centre and the ancillary ligands, i.e. coordination,
insertion and reduction, may allow the synthesis of unusual tran-
sition metal compounds and clusters as we have recently found for
main-group elements [13,14].
1371(vs), 1348(m), 1304(vs), 1252(m), 1242(s), 1165(s), 1091(w),
1048(w), 1010(s), 990(w), 931(w), 856(s), 787(vs), 749(vs), 703(w),
524(w), 437(s). Anal. Calcd (%) for C37H53N2Cl2GaPt (861.53 g/mol):
C, 51.58; H, 6.20; N, 3.25; found: C, 51.15; H, 6.67; N, 4.25.
4.2. Preparation of [(dcy)Pt(Cl){ClGa(DDP)}] (3)
To a stirred solution of [(dcy)PtCl2] (0.08 g, 0.20 mmol) in
toluene (4 mL), 1 (0.097 g, 0.20 mmol) was added at room
temperature. The colour of the reaction mixture turns pale yellow
to brown. The resultant reaction mixture was stirred for 20 h and
then filtered to remove the insoluble black solid. The filtrate was
concentrated to 2 mL and stored to ꢀ30ꢂ C for one week to afford
pale yellow crystalline substance. Crystals formed were filtered,
quickly washed with n-hexane (2 ꢃ 3 mL) andꢂdried in vacuo. Yield:
28% (0.05 g, based on [(dcy)PtCl2]). Mp: > 180 C (decomp). 1H NMR
2
(d8-THF, 600.13 MHz):
d
¼ 7.92e7.83 (m, JPt-H ¼ 27 Hz, 1H, HeC4,
dcy), 7.22e7.14 (m, 6H, aromatic protons, Ga(DDP)), 6.19 (br, 1H,
HeC3, dcy), 5.15 (s, 1H, methine, Ga(DDP)), 4.87 (m, 1H, HeC1, dcy),
4.10e4.23 (m, 1H from HeC4, and 1H from HeC34), 3.93 (sept, 1H,
2JHH ¼ 7 Hz, HeC37), 3.49 (sept, 1H, 2JHH ¼ 6.8 Hz, HeC18, Ga(DDP)),
3.34e3.38 (m, 1H from HeC9 and 1H from HeC29), 3.28 (br, 1H,
HeC7, dcy), 2.86 (br, 1H, HeC6, dcy), 2.59e2.62 (br, 1H, HeC8, dcy),
1.81e1.86 (m, 2H, HeC5, dcy),1.77 (s, 3H, CH3, HeC15, Ga(DDP)),1.74
(s, 3H, HeC14, Ga(DDP)), 1.71e1.73 (m, 2H, HeC10, dcy), 1.59 (d, 3H,
4. Experimental
All manipulations were carried out in an atmosphere of purified
argon using standard Schlenk and glove-box techniques. Hexane
and toluene were dried using an MBraun Solvent Purification
System. The final H2O content in all solvents was checked by Karl
Fischer titration and did not exceed 5 ppm. Compounds [(1,5-COD)
PtCl2] [32], [(COD)Pd(Me)(OTf)] [33] and Ga(DDP) [5] were
prepared as previously described procedures. [(dcy)PtCl2] is
purchased from ABCR. Elemental analyses were performed by the
Microanalytical Laboratory of the Ruhr University Bochum. NMR
spectra were measured on a Bruker Avance DPX-250 and DRX-
600 MHz spectrometers in C6D6 and d8-THF at 298 K. Chemical
shifts are given relative to TMS and were referenced to the solvent
resonances as internal standards. Chemical shifts are described in
parts per million, downfield shifted from TMS, and are consecu-
tively reported as position (dH or dC), relative integral, multiplicity
(s ¼ singlet, d ¼ doublet, sept ¼ septet, m ¼ multiplet), coupling
constant (J in Hz) and assignment. IR measurement (neat) was
carried out on a Bruker Alpha-P Fourier transform spectrometer.
2
2JHH ¼ 6 Hz, H-C35, Ga(DDP)), 1.56 (d, 3H, JHH ¼ 6.4 Hz, HeC34,
2
CHCH3), 1.32 (d, 3H, JHH ¼ 7 Hz, HeC39, CHCH3), 1.30 (d, 3H,
2
2JHH ¼ 6 Hz, HeC38, CHCH3), 1.23 (d, 3H, JHH ¼ 6.7 Hz, HeC17,
2
CHCH3), 1.20 (d, 3H, JHH ¼ 7.4 Hz, HeC16, CHCH3), 1.12 (d, 3H,
2
2JHH ¼ 6 Hz, HeC26, CHCH3), 1.07 (d, 3H, JHH ¼ 6.5 Hz, HeC27
,
CHCH3) ppm. 13C NMR (d8-THF, 150.90 MHz):
DDP), 170.7(C11eN, DDP), 146.3(C28(Dipp)-N), 146.1(C24(Dipp)-N),
145.6(o-C33(Dipp)), 145.4(o-C23(Dipp)), 142.6(o-C29(Dipp)), 141.9(o-
C19(Dipp)), 139.4(C4]C, dcy), 132.6(C3]C, dcy), 127.9(p-C31(Dipp)),
d
¼ 170.9(C13eN,
127.7(o-C21(Dipp)),
124.9(m-C22(Dipp)), 124.8 (m-C20(Dipp)), 100.4(
125.2(m-C30(Dipp)),
125.0(m-C32(Dipp)),
-C12, Ga(DDP)),
g
85.2(C1]C, dcy), 83.2(C2]C, dcy), 59.1(C5, dcy), 57.5(C9, dcy),
52.7(C7, dcy), 48.0(C6, dcy), 43.5(C8, dcy), 33.8(C10eC]C, dcy),
29.6(C34H(CH3)2), 29.5(C37H(CH3)2), 29.4(C18H(CH3)2), 28.8(C25
(CH3)2), 27.8(C35H(CH3)2), 26.8(C36H(CH3)2), 25.7(C39H(CH3)2), 25.6
(C38H(CH3)2), 25.4 (C17H(CH3)2), 25.3(C16H(CH3)2), 25.2(C26
H
4.1. Preparation of [(COD)Pt(Cl){ClGa(DDP)}] (2)
H
(CH3)2), 24.8(C27H(CH3)2), 24.6(C15eC), 24.3(C14eC) ppm. IR
(cmꢀ1): 2939(s), 2901(w), 1517(vs), 1449(w), 1426(s), 1371(vs),
1305(vs), 1251(s), 1167(s), 1010(s), 929(s), 857(s), 790(vs), 753(s),
728(vs). Anal. Calcd (%) for C39H53Cl2N2GaPt (885.58 g/mol):
C, 52.90; H, 6.03; N, 3.16; found: C, 53.50; H, 6.45; N, 2.93.
To a stirredsuspension of [(1,5-COD)PtCl2] (0.05 g, 0.133mmol) in
toluene (2 mL), 1 (0.065 g, 0.133 mmol) was added at room
temperature. In few minutes the pale yellow slurry became orange
then to brown. The resultant reaction mixture was stirred for 24 h

2640
A. Doddi et al. / Journal of Organometallic Chemistry 696 (2011) 2635e2640
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[(DDP)Ga(Me)(OTf)] (4)
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Ga(DDP) (0.09 g, 0.184 mmol) in toluene (1 mL) was added to
a Schlenk tube containing [(COD)Pd(Me)(OTf)] (0.07 g, 0.184 mmol)
ꢂ
in fluorobenzene (3 mL) at ꢀ40 C. The resultant reaction mixture
was immediately turned to dark brown with formation of a grey-
black solid. It was slowly warmed to room temperature over
a period of 30 min and stirred for another 30 min. The grey-black
precipitate formed was filtered off and the filtrate was completely
evaporated under reduced pressure, dissolved in toluene (2 mL) and
stored at ꢀ30 ꢂC. Colourless crystals formed in 3 days were filtered,
quickly washed with n-hexane (2 ꢃ 4 mL) and dried in vacuo. Yield:
33% (0.04 g, based on [(COD)Pd(Me)(OTf)]. Mp: 169e171 ꢂC. 1H NMR
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9758e9759;
(C6D6, 250 MHz):
d
¼ 7.15e7.00 (m, 6H, Ar CH), 5.16 (s,1H,
g-CH), 3.84
(broad, 2H, CH(Me)2), 2.84 (broad, 2H, CH(Me)2), 1.57 (s, 6H, CH3),
1.34e1.32 (broad, 12H, CH(Me)2), 1.07e0.98 (broad, 12H, CH(Me) 2),
ꢀ0.46 (s, 3H, GaeCH3)ppm; 13CNMR (C6D6, 62.8952MHz):
¼ 172.1
d
(b) R.J. Baker, R.D. Farley, C. Jones, M. Kloth, D.M. Murphy, J. Chem. Soc. Dalton
Trans. (2002) 3844e3850.
(C]N), 146.4 (C(Dipp)-N), 145.4 (C(Dipp)-N), 143.1 (o-C(Dipp)),
[9] C. Jones, P.C. Junk, J.A. Platts, A. Stasch, J. Am. Chem. Soc. 128 (2006)
2206e2207.
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3133e3138;
139.2 (o-C(Dipp)), 124.1 (m-C(Dipp)), 125.5 (p-C(Dipp)), 100.7 (g-C),
28.7 (CHMe2), 27.4 (CHMe2), 25.2 (CMe), 24.5 (CMe), 23.6 (CHMe2),
ꢀ13.8 (GaeCH3) ppm. The 13C NMR resonance of the triflate group
could not be detected. IR (n
, cmꢀ1): 2940(s), 2906(vw), 1507(vs),
1450(w), 1428(w), 1364(vs), 1335(w), 1306(vw), 1280(w), 1250(s),
1226(vs), 1193(vs), 1174(vs), 1090)(w), 1013(vs), 994(vs), 938(w),
867(vw), 794(vs), 754(s), 624(vs), 514(vw), 497(vw), 447(w). Anal.
Calcd (%) for C31H44F3GaN2O3S (651.4862 g/mol). C, 57.15; H, 6.81; N,
4.30; S, 4.92; found: C, 55.91; H, 6.87; N, 4.03; S, 7.29.
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Eur. J. Inorg. Chem. (2010) 4415e4418.
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Angew. Chem. Int. Ed. 48 (2009) 5526e5529.
4.4. X-ray crystallography
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Chem. Int. Ed. Engl. 47 (2008) 7234e7237.
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(2010) 6041e6047.
[16] M. Cokoja, C. Gemel, T. Steinke, F. Schröder, R.A. Fischer, Dalton.Trans. (2005)
44e54.
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Commun. 24 (2000) 2495e2496.
The X-ray crystal structures were measured with an Oxford
Excalibur 2 diffractometer using MoK radiation (
l
¼ 0.71073 Å).
a
The structures were solved by direct methods using SHELXS-97 and
refined against F2 on all data by full-matrix least-squares with
SHELXL-97 [34].
Acknowledgement
[19] R.A. Fischer, D. Weiß, T. Steinke, M. Winter, G. Frenking, N. Froehlich, J. Uddin,
Organometallics 19 (2000) 4583e4588.
[20] T. Steinke, C. Gemel, M. Winter, R.A. Fischer, Chem. Eur. J. 11 (2005) 1636e1646.
[21] B. Buchin, C. Gemel, T. Cadenbach, I. Fernández, G. Frenking, R.A. Fischer,
Angew. Chem. Int. Ed. Engl. 45 (2006) 5207e5210.
[22] C. Gemel, T. Steinke, D. Weiss, M. Cokoja, M. Winter, R.A. Fischer, Organo-
metallics 22 (2003) 2705e2710.
We are thankful to Mr. Martin Gartmann, Biomolecular NMR
facility at Ruhr University Bochum for 2D NMR measurements.
Appendix
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9146e9149.
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[29] A. Syed, E.D. Stevens, S.G. Cruz, Inorg. Chem. 23 (1984) 3673e3674.
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(2010) 7976e7980.
CCDC-801252(2), ꢀ801253(3) contain the supplementary crys-
tallographic 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.
Appendix Supporting information
[31] (a) T. Cadenbach, C. Gemel, D. Zacher, R.A. Fischer, Angew. Chem. Int. Edit. 47
(2008) 3438e3441;
Supplementary data related to this article can be found online at
doi:10.1016/j.jorganchem.2011.04.008.
(b) T. Cadenbach, C. Gemel, T. Bollermann, I. Fernandez, G. Frenking,
R.A. Fischer, Chem. Eur. J. 14 (2008) 10789e10796;
(c) T. Bollermann, G. Prabusankar, C. Gemel, R.W. Seidel, M. Winter,
R.A. Fischer, Chem. Eur. J. 16 (2010) 8846e8853.
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