Bis(allyl)gallium Cation, tris(allyl)gallium, and tetrakis(allyl)gallate: Synthesis, characterization, and reactivity

Article abstract of DOI:10.1021/ic202293t

A series of cationic, neutral, and anionic allylgallium complexes has been isolated and fully characterized. It includes neutral [Ga(ν₁- C₃H₅)₃(L)] (1, L = THF; 2, L = OPPh ₃), cationic [Ga(ν¹

Full text of DOI:10.1021/ic202293t

Article
pubs.acs.org/IC
Bis(allyl)gallium Cation, Tris(allyl)gallium, and Tetrakis(allyl)gallate:
Synthesis, Characterization, and Reactivity
Crispin Lichtenberg, Thomas P. Spaniol, and Jun Okuda*
Institute of Inorganic Chemistry, RWTH Aachen University, Landoltweg 1, D-52056 Aachen, Germany
S
* Supporting Information
ABSTRACT: A series of cationic, neutral, and anionic
allylgallium complexes has been isolated and fully charac-
terized. It includes neutral [Ga(η1-C3H5)3(L)] (1, L = THF; 2,
L = OPPh3), cationic [Ga(η1-C3H5)2(THF)2]+[A]− (3, [A]− =
[B(C6F5)4]−; 4, [A]− = [B(C6H3Cl2)4]−), as well as anionic
[Cat]+[Ga(η1-C3H5)4]− (5, [Cat]+ = K+; 6, [Cat]+
=
[K(dibenzo-18-c-6]+; 7, [Cat]+ = [PPh4]+). Binding modes
of the allyl ligand in solution and in the solid state have been studied comparatively. Single crystal X-ray analyses revealed a four-
coordinate neutral gallium center in 2, a five-coordinate cationic gallium center in 4 and [4·THF], and a four-coordinate anionic
gallium center with a bridging μ2-η1:η2 coordination mode of the allyl ligand in 6. The reactivity of this series of allylgallium
complexes toward benzophenone and N-heteroaromatics has been investigated. Counterion effects have also been studied.
Reactions of 1 and 5 with isoquinoline revealed the first examples of organogallium complexes reacting under 1,2-insertion with
pyridine derivatives.
synthesized by salt metathesis of gallium chloride with
allylpotassium in pentane/THF (5:1) (Scheme 1). Low
temperatures (−78 to −30 °C) had to be applied in this
reaction as well as during workup, since 1 is temperature
sensitive. Degradation of 1 at ambient temperature in
hydrocarbons is much faster than in donor solvents hinting at
an intermolecular degradation mechanism (in C6D6, t1/2 = 5
days, decomposition products detected by 1H NMR after a few
hours;8 in THF-d8, no decomposition products detected after
more than 14 days). NMR spectra of 1 in toluene-d8 at ambient
temperature show fluxional behavior of the allyl ligands with
the methylene groups giving rise to one broad resonance. An
AX4 pattern with one quintet and one doublet (relative
intensity 1:4) is observed at 90 °C in toluene-d8.9 The η1
bonding mode of the allyl ligands with its AMNX2 pattern is
recorded at −60 °C in toluene-d8 or at ambient temperature in
THF-d8. Thus, donor solvents significantly slow down the allyl
exchange rate in 1. In [Ga(η1-C3H3(SiMe3)2)3], the η1 bonding
mode in toluene-d8 solution was not frozen out at temperatures
as low as −75 °C.5 When comparing 1 to the homologous allyl
complexes [E(η1-C3H5)3(L)] (E = Al, In; L = neutral ligand),
the rate of allyl exchange reactions increases in the order Al <
Ga < In.10,11 This is ascribed to (i) the ionic radii of the metal
centers and (ii) the shielding of the cationic charge of the metal
centers by core electrons, which both increase in the same
order.
INTRODUCTION
■
In recent years, organogallium compounds have attracted
interest in homogeneous catalysis1 and organic synthesis.2
Organogallium reagents combine a moderate Lewis acidity with
a relatively low polarity of the metal−carbon bond.2b,d Their
reactivity significantly differs not only from organolithium,
-magnesium, -copper, and -tin compounds, but in some cases also
from homologous organoaluminum and -indium reagents.2b,d,g
Due to the importance of the allyl substituent in organic synthesis,
there is an ongoing effort to develop allyl transfer reagents.3
Consequently, allylgallium species have frequently been applied in
organic synthesis.4 However, these reagents are mostly generated
in situ and remain ill-defined. Only one allylgallium compound,
[Ga(η1-C3H3(SiMe3)2)3], has been isolated and fully characterized
but has not been subjected to reactivity studies.5
None of the allylgallium reagents mentioned above bear
formal charges at the metal center. In general, charged
organogallium species have also been in the focus of research
efforts since their characteristics differ notably from their
neutral parent compounds.2d,6 Cationic organogallium com-
pounds show enhanced Lewis acidity as demonstrated by rapid
polymerization of propylene oxide or cyclohexene oxide, for
instance.1a,d Anionic tetrakis(organo)gallate moieties have been
used in organic reactions and as chelating ligands in the
synthesis of heterobimetallic complexes.7 We report here the
synthesis and characterization of cationic, neutral, and anionic
allylgallium complexes along with their reactivity toward
electrophilic substrates.
The THF ligand in [Ga(η1-C3H5)3(THF)] (1) could not be
removed by exposing 1 to reduced pressure, but is labile in
the presence of excess THF-d8 or stoichiometric amounts of
RESULTS AND DISCUSSION
Neutral Allylgallium Complexes. The THF adduct of the
parent allylgallium complex, [Ga(η1-C3H5)3(THF)] (1), was
■
Received: October 23, 2011
Published: January 23, 2012
© 2012 American Chemical Society
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Scheme 1. Synthesis of Tris(allyl)gallium Compounds 1 and 2, Bis(allyl)gallium Cations 3 and 4, and Tetrakis(allyl)gallates 5,
a
6, and 7
a
3, [A]− = [B(C6F5)4]−; 4, [A]− = [B(C6H3Cl2)4]−.
stronger neutral donors. Reaction of 1 with 1 equiv of tri-
phenylphosphine oxide OPPh3 gave [Ga(η1-C3H5)3(OPPh3)]
(2) (Scheme 1). The OPPh3 ligand in 2 is also labile as shown
by 1H and 31P NMR spectroscopic analysis of a THF-d8
solution containing equimolar amounts of OPPh3 and 2. On
the basis of VT 31P NMR spectroscopic measurements, the
exchange rate of the OPPh3 ligands was estimated to be kC =
2 × 103 s−1 at the coalescence temperature of TC = 178 K. The
coalescence temperature is more than 100 K lower than for the
same process of [Al(η1-C3H5)3(OPPh3)].12 Thus, the M−
OPPh3 bond is weaker in the case of the Ga compound when
compared with the Al congener.13
Figure 1. Molecular structure of [Ga(η1-C3H5)3(OPPh3)] (2).
Displacement ellipsoids are drawn at the 50% probability level.
Hydrogen atoms have been omitted for clarity. Atoms C7, C8, and C9
are shown with only one split position. Selected bond lengths [Å] and
angles [deg]: Ga1−C1, 2.001(3); Ga1−C4, 1.981(3); Ga1−O1,
1.980(2); C1−C2, 1.495(5); C2−C3, 1.250(5); C4−C5, 1.451(5);
C5−C6, 1.328(5); O1−P1, 1.490(2); C1−Ga1−C4, 113.78(15); C1−
Ga1−O1, 97.96(11); C4−Ga1−O1, 103.90(12); C1−C2−C3,
130.0(5); C4−C5−C6, 127.4(4); Ga1−O1−P1, 159.21(14).
Single crystals of 2 were obtained by cooling a saturated
solution in CH2Cl2/pentane to −30 °C. Compound 2
crystallized in the monoclinic space group P21/c with Z = 4.
The gallium center is found in a distorted tetrahedral
coordination geometry (C−Ga−C/O, 97.6(4)−120.0(4)°)
(Figure 1). The allyl ligands adopt an η1 bonding mode with
one long and one short C−C bond in each allyl group. The
same bonding mode has been reported for [Ga(η1-
C3H3(SiMe3)2)3].5 A mean Ga−C bond length of 1.995 Å is
found in 2, which ranges between the corresponding values for
[Ga(η1-C3H3(SiMe3)2)3] and [Ga(tBu)2R(OPPh3)] (R =
aryl).5,14 The Ga1−O1−P1 angle in 2 (159.21(14)°) deviates
from 180°, suggesting that the OPPh3 ligand is a pure σ donor.
In contrast, [GaCl3(OPPh3)] shows a linear Ga−O−P unit.15
Cationic Allylgallium Complexes. Cationic allylgallium
complexes [Ga(η1-C3H5)2(THF)2]+[A]− (3, [A]− = [B(C6F5)4]−;
4, [A]− = [B(C6H3Cl2)4]−) were obtained by treating 1 with
dimethylanilinium borates (Scheme 1). The allyl ligands in 3 and
4 exhibit an η1 binding mode in THF-d8 solutions at ambient
common.6a,b The Ga1−Cl7 distance of 3.5113(16) Å is longer
than Ga−Cl bonds in other cationic gallium species (ca. 2.2 Å)
and only 3% below the sum of the van der Waals radii of Ga and
Cl.16 Consequently, the Ga−Oaxial bond (2.001(3) Å) is only
slightly longer than the Ga−Oequatorial bond (1.973(3) Å). The allyl
ligands show an η1 bonding mode with one short and one long
C−C bond within each allyl group. The mean Ga−C bond length
in 4 (1.966(4) Å) is significantly shorter than the corresponding
values in neutral [Ga(η1-C3H5)3(OPPh3)] (6) or [Ga(η1-
C3H3(SiMe3)2)3].5 This is ascribed to the increased Lewis acidity
of cationic 4. The weak Ga−Cl contact in 4 hinted at the tendency
of the gallium center in the [Ga(η1-C3H5)2(THF)2]+ complex
cation to increase its coordination number from four to five. To
provide further evidence for this, 4 was crystallized from a
saturated solution in THF/pentane at −30 °C to give colorless
blocks of [4·THF] as shown by single crystal X-ray analysis
(Figure 2b). [4·THF] crystallized in the orthorhombic space
group P212121 with two crystallographically independent formula
units (Z = 8) that exhibit highly similar structural parameters.
1
temperature. The THF ligands are labile as shown by H NMR
spectroscopy. Cooling a solution of 4 in CH2Cl2/pentane (1:2) to
−30 °C gave colorless, block-shaped single crystals. Compound 4
crystallized in the triclinic space group P1 with Z = 2. The gallium
̅
center in 4 experiences weak contacts with a Cl atom of the
counterion (Figure 2a). Thus, a coordination number of five and a
distorted trigonal bipyramidal coordination geometry were
assigned (O1−Ga1−Cl7, 167.84(9)°; Σ(C−Ga−Oequatorial),
348.9(2)°), although four-coordinate gallium cations are most
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units in the asymmetric unit (Z = 8) with highly similar
structural parameters. The gallium center in 6 adopts a slightly
distorted tetrahedral coordination geometry (C−Ga−C,
103.79(14)−113.93(13)°) (Figure 3). Three of the allyl ligands
Figure 2. Molecular structures of the cationic parts of (a) [Ga(η1-
C3H5 )2 (THF)2]+[B(C6 H3 Cl2 )4]− (4) and (b) [Ga(η1-
C3H5)2(THF)3]+[B(C6H3Cl2)4]− ([4·THF]). A Cl atom which is
part of the counterion and shows weak contacts to the Ga center is
shown for 4 (a). For [4·THF], only one of the two crystallographically
independent cations is shown. Displacement ellipsoids are shown at
the 50% probability level. Hydrogen atoms are omitted for clarity.
Selected bond lengths [Å] and angles [deg]: (a) Ga1−C1, 1.962(4);
Ga1−C4, 1.969(4); Ga1−O1, 2.001(3); Ga1−O2, 1.973(3); Ga1−
Cl7, 3.5113(16); C1−C2, 1.479(6); C2−C3, 1.311(6); C4−C5,
1.483(6); C5−C6, 1.302(6); O1−Ga1−O2, 92.09(12); O1−Ga1−C1,
102.36(16); O1−Ga1−C4, 105.77(16); O2−Ga1−C1, 107.49(17);
O2−Ga1−C4, 108.57(16); C1−Ga1−C4, 132.7(2); O1−Ga1−Cl7,
167.84(9); C1−C2−C3, 126.7(5); C4−C5−C6, 126.5(4). (b) Ga1−
C1, 1.968(4); Ga1−C4, 1.966(4); Ga1−O1, 2.235(2); Ga1−O2,
2.186(2); Ga1−O3, 1.987(2); C1−C2, 1.479(5); C2−C3, 1.300(5);
C4−C5, 1.491(5); C5−C6, 1.312(5); O1−Ga1−O2, 162.51(9); O1−
Ga1−O3, 80.82(9); O3−Ga1−C1, 116.91(13); O3−Ga1−C4,
113.95(13); C1−Ga1−C4, 129.13(15); C1−C2−C3, 126.9(4); C4−
C5−C6, 125.8(4).
Figure 3. Dimeric arrangement of [K(dibenzo-18-c-6)]+[Ga(η1-
C3H5)4]− (6) in the solid state. One of two crystallographically
independent dimers is shown. Displacement ellipsoids are drawn at the
50% probability level. Hydrogen atoms have been omitted for clarity.
Atom C8 is shown with only one split position. Selected bond lengths
[Å] and angles [deg]: Ga1−C1, 2.025(3); Ga1−C4, 2.052(3); Ga1−
C7, 2.013(3); Ga1−C10, 2.023(3); K1−C2, 3.278(3); K1−C3,
3.355(3); K1−C32′, 3.343(3); K1−C33′, 3.293(3); K1−(O1−O6),
2.766(2)−2.813(2); C1−Ga1−C4, 103.8(1); C1−Ga1−C7, 110.5(1);
C1−Ga1−C10, 107.6(1); C4−Ga1−C7, 110.2(1); C4−Ga1−C10,
110.3(1); C7−Ga1−C10, 113.9(1); center(C2−C3)−K1−center-
(C32′−C33′), 165.30(8); C1−C2−C3, 128.5(4); C4−C5−C6,
128.2(4); C7−C8A−C9, 131.0(7); C10−C11−C12, 128.3(4).
coordinate to the gallium center in an η1 fashion. One allyl
ligand adopts a bridging μ2-η1:η2 coordination mode; i.e., it
shows a σ type interaction with the gallium ion and its double
bond of localized type binds to the potassium ion. This is the
first structurally authenticated example of a μ2-η1:η2 coordina-
tion mode in group 13 allyl complexes,21,22 suggesting the
importance of counterion effects. In contrast to other
tetrakis(organo)gallates,7b−f the organic ligands in 6 do not
interact via the same carbon atom with two different metal
centers. All Ga−C bond lengths are similar and average to
2.029(3) Å, which is longer than corresponding mean values in
neutral 2 and cationic 4 or [4·THF], but compares well to
corresponding mean values in other tetrakis(organo)gallates.23
The potassium ion in 6 shows a hexagonal bipyramidal
coordination geometry with the equatorial positions being
occupied by oxygen atoms of the crown ether ligand. The CC
double bond of an allyl ligand is found in one of the axial
positions. The second axial position is occupied by an aromatic
C−C bond which is part of the crown ether ligand (center-
(C2−C3)−K1−center(C32′−C33′), 165.30(2)°). This leads to a
Ci symmetrical dimeric arrangement of two formula units of 6 in
the solid state. K−C distances range from 3.278(3) to 3.355(3) Å,
which compare well to literature values.24
Reactivity of Allylgallium Species toward Benzophe-
none. The reactivity of cationic, neutral, and anionic
allylgallium species toward benzophenone in THF solution at
ambient temperature was investigated (Scheme 2). A stoichiom-
etry of 1 equiv of benzophenone per allyl substituent was used.
Neutral [Ga(η1-C3H5)3(THF)] (1) gave the expected insertion
product 8 within a reaction time of t ≤ 10 min in full conversion.
For cationic 3, insertion of only 1 equiv of benzophenone was
observed within t ≤ 10 min. The resulting cationic alkoxy species
9 subsequently initiated polymerization of THF.25 The same was
observed for cationic 4. Tetrakis(allyl)gallate 5 also inserted
The gallium center in [4·THF] shows a coordination number of five,
which is highly unusual for cationic gallium complexes.6a,b This is the
first example of a five-coordinate, cationic organogallium
compound without chelating ligands and any direct interactions
with the counterion.6a,b,17,18 The coordination polyhedron found
in the cationic part of [4·THF] is a trigonal bipyramid. As the
THF ligands are weaker σ donors than the η1 bound allyl moieties,
they occupy the axial positions interacting with the same orbital of
the central atom (O1−Ga1−O2, 162.51(9)°).19 Consequently, the
third THF ligand and the two allyl moieties are located in equatorial
positions (Σ(C−Ga−Oequatorial), 360.0(2)°). Ga−C bond lengths are
highly similar and average to 1.968(4) Å, which is equal within limits
of error to the corresponding value found in 4. The Ga−Oequatorial
bond length (1.987(2) Å) is much shorter than the Ga−Oaxial bond
lengths (2.186(2) Å and 2.235(2) Å), since the two axial ligands
experience a thermodynamic trans effect. Ga−O bond lengths in
comparable compounds range between the corresponding values
observed in [4·THF].17
Anionic Allylgallium Complexes. The potassium tetrakis-
(allyl)gallate K+[Ga(η1-C3H5)4]− (5) was obtained by reacting
neutral 1 with 1 equiv of allylpotassium (Scheme 1). Addition
of 1 equiv of dibenzo-18-c-8 gave [K(dibenzo-18-c-6)]+[Ga(η1-
C3H5)4]− (6). Substitution of the potassium ion was achieved
by treating 5 with [PPh4]+Br− to give [PPh4]+[Ga(η1-C3H5)4]−
(7) (Scheme 1). 1H NMR spectroscopic analysis of 5, 6, and 7
in THF-d8 solutions at ambient temperature indicate an η1
binding mode of the allyl ligands.20 Single crystals of 6 were
obtained by cooling a saturated CH2Cl2/pentane (3:1) solution
to −30 °C. Compound 6 crystallized in the monoclinic space
group P21/c with two crystallographically independent formula
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Scheme 2. Reactivity of Tris(allyl)gallium 1,
Bis(allyl)gallium Cation 3, and Tetrakis(allyl)gallate 5
towards Benzophenone
Scheme 3. Reactivity of Tris(allyl)gallium 1,
Bis(allyl)gallium Cation 3, and Tetrakis(allyl)gallate 5
towards Isoquinoline
benzophenone. This reaction was substantially slower than those
of the cationic and neutral allylgallium species, probably due to
negligible Lewis acidity of 5.26 Moreover, no full conversion was
observed, but the reaction essentially stopped after insertion of 2
equiv of benzophenone to give the alkylalkoxy gallate 10 after a
reaction time of 53 h. Reaction of [PPh4]+[Ga(η1-C3H5)4]− (7)
with 4 equiv of benzophenone proceeded with a similar initial rate,
but selective insertion of 75% of the substrate was observed. Thus,
in reactions of tetrakis(allyl)gallates 5 and 7 with benzophenone,
insertion of the first equivalent of ketone proceeds without a
significant counterion effect. The reactivity of the resulting alkoxy-
gallates, however, is counterion dependent (for time conversion
plot of reactions of 5 and 7 with benzophenone, see Supporting
Information). Overall, neutral 1 was most efficient in the allylation
of benzophenone and proved superior compared to in situ
generated allylgallium species reported in the literature.27 Gallates
5 and 7 reacted much more slowly, but still with 100% selectivity.
Reactivity of Allylgallium Species toward N-Hetero-
aromatics. Lewis base adducts of tris(allyl)boron have been
reported to react with pyridine under 1,2 insertion.28 Recently,
this type of insertion chemistry has been extended to Lewis
base adducts of tris(allyl)aluminum.12 In contrast to the lighter
group 13 homologues, none of the allylgallium species 1, 3, and
5 reacted with pyridine or quinoline under insertion. Instead,
substitution of the THF ligands for N-heteroaromatics was
observed for 1 and 3, as shown by 1H and 13C NMR
spectroscopy. Pronounced differences between cationic, neu-
tral, and anionic allylgallium species in their reactivity toward
N-heteroaromatics became apparent, when isoquinoline was
chosen as a substrate: whereas substitution of the THF ligands
was observed for cationic 3, 1,2-insertion pathways were found
to occur with neutral 1 and anionic 5 (Scheme 3). Under
optimized reaction conditions, 1 reacted with 2 equiv of
isoquinoline within t ≤ 10 min to give the 1-allylated insertion
product 11 with a selectivity of 92%.29 The insertion reaction
between tetrakis(allyl)gallate 5 and 1 equiv of isoquinoline to
give 13 was substantially slower (17 h until full conversion), but
no side products were detected.29b The connectivity in the
anionic part of 13 was proved by single crystal X-ray analysis of
a derivative of this insertion product (compound 14, see
Supporting Information). Whereas adduct formation of
organogallium complexes with pyridine and its derivatives is
well documented,30 1 and 5 are the first examples of
organogallium species to exhibit insertion reactivity patterns
toward N-heteroaromatics. The fact that allylgallium species
show a decreased reactivity toward pyridine compared to the
boron and aluminum homologues could be ascribed to the
higher Lewis acidity of the latter compounds.
CONCLUSIONS
■
The THF adduct of previously elusive tris(allyl)gallium,
[Ga(η1-C3H5)3(THF)] (1), was isolated as a liquid; crystalline
[Ga(η1-C3H5)3(OPPh3)] (2) could be fully characterized.
Protonolysis of one allyl ligand of 1 gave the cationic
allylgallium species [Ga(η1-C3H5)2(THF)2]+[A]− (3, A =
[B(C6F5)4]−; 4, A = [B(C6H3Cl2)4]−). In the solid state, 4
and [4·THF] show a five-coordinate gallium center in a trigonal
bipyramidal coordination geometry. Potassium gallate K+[Ga-
(η1-C3H5)4]− (5) was synthesized from allylpotassium and 1.
The adduct [K(dibenzo-18-c-6)]+[Ga(η1-C3H5)4]− (6) was
fully characterized and shows a bridging μ2-η1:η2 coordination
mode of one allyl ligand in the solid state, which is
unprecedented for group 13 compounds. In all allylgallium
compounds of this work, the allyl ligands show σ type
interactions with the gallium center in the solid state and in
solution. The reactivity of a series of cationic, neutral, and
anionic allylgallium complexes (1, 3, 5) toward benzophenone
and N-heteroaromatics was investigated. Neutral 1 was an
effective allylation reagent for benzophenone and proved
superior compared to in situ generated allylgallium reagents
previously reported. Neutral 1 and anionic 5 reacted with
isoquinoline under 1,2-insertion.
EXPERIMENTAL SECTION
■
General Remarks. All operations were carried out under argon
using standard Schlenk-line and glovebox techniques. Starting
materials were purchased from Sigma Aldrich or Boulder Scientific
and purified following standard laboratory procedures. Starting
materials which were not commercially available were synthesized
according to the literature. [NHMe2Ph][B(C6H3Cl2)4] was synthe-
sized in analogy to protocols established for [NHMe2Ph][BPh4].
Nondeuterated solvents were purified using an MB SPS-800 solvent
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purification system. Benzene-d6 and THF-d8 were distilled from
sodium benzophenone ketyl. Py-d5 was distilled from calcium hydride.
NMR spectra were recorded at ambient temperature using a Varian
Mercury-200 or a Bruker Avance II 400 MHz spectrometer. The
chemical shifts of 1H and 13C NMR spectra were referenced internally
using the residual solvent resonances and are reported relative to the
chemical shift of tetramethylsilane. The resonances in 1H and 13C
NMR spectra were assigned on the basis of two-dimensional NMR
experiments (COSY, HMQC, HMBC) when necessary. The
resonances recorded in 11B, 19F, and 31P NMR measurements are
reported relative to external standards, an ethereal solution of
BF3·Et2O, CFCl3, and phosphoric acid (85%), respectively. The
metal content of organogallium compounds was determined by
titration.31 Elemental analyses were performed by the microanalytical
laboratory of the Institute of Organic Chemistry at the RWTH Aachen
University.
1H NMR (400.1 MHz, CD2Cl2): δ = 1.28 (br s, 6H, CH2−CH
CH2), 4.35 (br s, 3H, CH2−CHCHcisHtrans), 4.45 (br d, 3JHH = 14.8
Hz, 3H, CH2−CHCHcisHtrans), 5.90−6.01 (m, 3H, CH2−CH
CH2), 7.50−7.54 (m, 6H, m-Ph), 7.63−7.68 (m, 9H, p-Ph, o-Ph) ppm.
13C NMR (100.6 MHz, THF-d8): δ = 22.37 (s, CH2−CHCH2),
106.37 (s, CH2−CHCH2), 129.66 (d, 3JCP = 13.9 Hz, m-Ph), 132.45
1
2
(d, JCP = 102.3 Hz, ipso-Ph), 133.32 (d, JCP = 9.5 Hz, o-Ph), 133.47
(d, 4JCP = 3.5 Hz, p-Ph), 142.29 (s, CH2−CHCH2) ppm. 13C NMR
(100.6 MHz, CD2Cl2): δ = 22.63 (br s, CH2−CHCH2), 105.66 (br
3
2
s, CH2−CH=CH2), 129.39 (d, JCP = 12.1 Hz, m-Ph), 132.96 (d, JCP
4
= 10.4 Hz, o-Ph), 133.62 (d, JCP = 2.6 Hz, p-Ph), 142.69 (s, CH2−
CHCH2) ppm. A resonance due to the ispo-carbon atom was not
detected. 31P NMR (162.0 Hz, THF-d8): δ = 30.60 (s) ppm. 31P NMR
(162.0 Hz, CD2Cl2): δ = 35.69 (s) ppm. Anal. Calcd for C27H30GaOP
(471.22 g/mol): Ga, 14.80. Found: Ga, 15.20.
[Ga(η1-C3H5)2(THF)2]+[B(C6F5)4]− (3). A solution of [NHMe2Ph]-
[B(C6F5)4] (58 mg, 0.072 mmol) in THF (600 μL) was added to a
solution of 1 (20 mg, 0.076 mmol) in THF (400 μL) to give a
colorless solution. After 10 min pentane (15 mL) was added, upon
which a colorless oil precipitated. The supernatant was decanted and
the residue washed with pentane (5 × 2 mL) to give a colorless solid,
which was dried in vacuo for 1.5 h. Yield: 67 mg (0.069 mmol), 96%.
1H NMR (400.1 MHz, THF-d8): δ = 1.76−1.79 (m, 8H, β-THF),
[Ga(η1-C3H5)3(THF)] (1). At −78 °C, THF (2.0 mL) was added
dropwise to a suspension of GaCl3 (732 mg, 4.16 mmol) in pentane
(10 mL). Neat allylpotassium (1.00 g, 12.47 mmol) was added
portionwise. The reaction mixture was kept at −78 °C for 3 h. After
warming to −30 °C, the reaction mixture was filtered, and the residue
was washed with pentane/THF (5:1) (2 × 12 mL). All volatiles were
removed from the colorless filtrate under reduced pressure at −30 °C
to give a slightly yellow oil, which was dried in vacuo at the same
temperature for 2.5 h. Yield: 929 mg (3.51 mmol), 84%.
3
4
4
1.91 (ddd, JHH = 8.3 Hz, JHH = 1.5 Hz, JHH = 1.0 Hz, 4H, CH2−
2
CHCH2), 3.60−3.63 (m, 8H, α-THF), 4.86 (ddt, JHH = 1.8 Hz,
1H NMR (400.1 MHz, C6D6): δ = 1.08−1.12 (m, 4H, β-THF),
1.0−5.0 (br s, 12H, CH2CHCH2), 3.31−3.35 (m, 4H, α-THF), 6.26
3JHH = 10.0 Hz, 4JHH = 1.0 Hz, 2H, CH2−CHCHcisHtrans), 5.00 (ddt,
2JHH = 1.8 Hz, JHH = 16.8 Hz, JHH = 1.5 Hz, 2H, CH2−CH
CHcisHtrans), 5.99 (ddt, 3JHH = 8.3 Hz, 3JHH = 10.0 Hz, 3JHH = 16.8 Hz,
2H, CH2−CH=CH2) ppm. 1H NMR (400.1 MHz, Py-h5/Py-d5(1:1)):
3
4
3
(quint, JHH = 11.0 Hz, 3H, CH2CHCH2) ppm. 1H NMR (400.1
MHz, Tol-d8, −60 °C): δ = 0.95−0.98 (m, 4H, β-THF), 1.68 (d, 3JHH
= 8.5 Hz, 6H, CH2−CHCH2), 3.16−3.99 (m, 4H, α-THF), 4.93 (br
3
δ = 1.60−1.63 (m, 8H, β-THF), 2.26 (d, JHH = 8.5 Hz, 4H, CH2−
2
3
dd, JHH = 2.8 Hz, JHH = 10.0 Hz, 3H, CH2−CHCHcisHtrans), 4.93
2
CHCH2), 3.67−3.64 (m, 8H, α-THF), 4.83 (ddt, JHH = 2.0 Hz,
2
3
4
3JHH = 10.0 Hz, 4JHH = 1.0 Hz, 2H, CH2−CHCHcisHtrans), 5.03 (ddt,
(ddt, JHH = 2.8 Hz, JHH = 16.8 Hz, JHH = 1.3 Hz, 3H, CH2−CH
CHcisHtrans), 6.30 (ddt, 3JHH = 8.5 Hz, 3JHH = 10.0 Hz, 3JHH = 16.8 Hz,
3H, CH2−CH=CH2) ppm. 1H NMR (400.1 MHz, Tol-d8, 24 °C): δ =
1.17−1.20 (m, 4H, β-THF), 1.0−5.0 (br s, 12H, CH2CHCH2), 3.35−
3.39 (m, 4H, α-THF), 6.18 (quint, 3JHH = 11.0 Hz, 3H, CH2CHCH2)
ppm. 1H NMR (400.1 MHz, Tol-d8, 90 °C): δ = 1.36−1.39 (m, 4H, β-
THF), 3.16 (br d, 3JHH = 11.0 Hz, 12H, CH2CHCH2), 3.47−3.50 (m,
4H, α-THF), 6.13 (quint, 3JHH = 11.0 Hz, 3H, CH2CHCH2) ppm. Up
to 19% of the starting material had undergone thermal decomposition
while heating the sample from ambient temperature to 90 °C over a
2JHH = 2.0 Hz, JHH = 16.8 Hz, JHH = 1.5 Hz, 2H, CH2−CH
CHcisHtrans), 6.03 (ddt, 3JHH = 8.5 Hz, 3JHH = 10.0 Hz, 3JHH = 16.8 Hz,
2H, CH2−CH=CH2) ppm. 13C NMR (100.6 MHz, THF-d8): δ =
20.57 (s, CH2−CHCH2), 26.53 (s, β-THF), 68.39 (s, α-THF),
114.00 (s, CH2−CHCH2), 125.53 (br s, ipso-C6F5), 135.59 (s,
CH2−CHCH2), 137.26 (dm, 1JCF = 241.9 Hz, m-C6F5), 139.29 (dm,
3
4
1JCF = 246.2 Hz, p-C6F5), 149.34 (dm, JCF = 241.9 Hz, o-C6F5) ppm.
1
11B NMR (128.4 MHz, THF-d8): δ = −18.45 (s) ppm. 19F NMR
1
1
(188.1 MHz, THF-d8): δ = −129.09 to −129.35 (m, m-C6F5),
period of 40 min according to H NMR spectra. H NMR (400.1
MHz, THF-d8): δ = 1.43 (br d, 3JHH = 8.8 Hz, 6H, CH2−CHCH2),
1.76−1.79 (m, 4H, β-THF), 3.60−3.63 (m, 4H, α-THF), 4.48 (br d,
3
3
−161.47 (t, JFF = 20.3 Hz, p-C6F5), −164.98 (t, JFF = 18.7 Hz, o-
C6F5) ppm. Anal. Calcd for C38H26BF20GaO2 (975.11 g/mol): Ga,
7.15. Found: Ga, 6.86.
3JHH = 9.3 Hz, 3H, CH2−CHCHcisHtrans), 4.63 (br d, JHH = 16.6
3
[Ga(η1-C3H5)2(THF)2]+[B(C6H3Cl2)4]− (4). [NHMe2Ph][B-
(C6H3Cl2)4] (50 mg, 0.070 mmol) was added to a solution of 1 (20
mg, 0.075 mmol) in THF (1 mL) to give a pale yellow solution. After
10 min pentane (9 mL) was added, upon which a colorless oil
precipitated, which turned into a colorless solid after 30 min. The
supernatant was decanted. The white solid washed with pentane (3 ×
2 mL) and dried in vacuo for 2 h. Yield: 61 mg (0.068 mmol), 97%.
1H NMR (400.1 MHz, THF-d8): δ = 1.75−1.79 (m, 8H, β-THF),
Hz, 3H, CH2−CHCHcisHtrans), 5.94−6.05 (m, 3H, CH2−CH=CH2)
1
ppm. H NMR (400.1 MHz, Py-h5/Py-d5(1:1)): δ = 1.60−1.64 (m,
3
4
4
4H, β-THF), 1.77 (ddd, JHH = 8.8 Hz, JHH = 1.0 Hz, JHH = 1.3 Hz,
6H, CH2−CHCH2), 3.64−3.67 (m, 4H, α-THF), 4.69 (ddt, 2JHH
=
2.8 Hz, JHH = 10.0 Hz, JHH = 1.0 Hz, 3H, CH2−CHCHcisHtrans),
3
4
2
3
4
4.82 (ddt, JHH = 2.8 Hz, JHH = 16.8 Hz, JHH = 1.25 Hz, 3H, CH2−
CHCHcisHtrans), 6.28 (m, 3JHH = 8.8 Hz, 3JHH = 10.0 Hz, 3JHH = 16.8
Hz, 3H, CH2−CHCH2) ppm. 13C NMR (50.3 MHz, C6D6): δ =
25.60 (s, β-THF), 70.54 (s, α-THF), 141.15 (s, CH2CHCH2) ppm. A
signal for the methylene carbon atoms could not be detected, not even
with more than 20 000 scans. 13C NMR (50.3 MHz, THF-d8): δ =
21.29 (s, CH2−CHCH2), 26.54 (s, β-THF), 68.39 (s, α-THF),
107.32 (s, CH2−CHCH2), 141.39 (s, CH2−CHCH2) ppm. Anal.
Calcd for C13H23GaO (265.04 g/mol): Ga, 26.31. Found: Ga, 27.02. A
test for halides was negative.
3
4
4
1.89 (ddd, JHH = 8.3 Hz, JHH = 1.1 Hz, JHH = 1.1 Hz, 4H, CH2−
2
CHCH2), 3.60−3.64 (m, 8H, α-THF), 4.86 (ddt, JHH = 1.9 Hz,
3JHH = 10.0 Hz, 4JHH = 1.0 Hz, 2H, CH2−CHCHcisHtrans), 4.99 (ddt,
2JHH = 1.9 Hz, JHH = 16.9 Hz, JHH = 1.5 Hz, 2H, CH2−CH
3
4
CHcisHtrans), 5.98 (ddt, 3JHH = 8.3 Hz, 3JHH = 10.0 Hz, 3JHH = 16.9 Hz,
4
2H, CH2−CHCH2) 6.97 (t, JHH = 2.0 Hz, 4H, p-(C6H3Cl2)),
7.02−7.04 (m, 8H, o-(C6H3Cl2)) ppm. 1H NMR (400.1 MHz, Py-d5):
δ = 1.61−1.65 (m, 8H, β-THF), 2.24 (ddd, JHH = 8.3 Hz, 4JHH = 0.9
3
[Ga(η1-C3H5)3(OPPh3)] (2). OPPh3 (100 mg, 0.36 mmol) was
added to a solution of 1 (95 mg, 0.36 mmol) in THF (0.8 mL) to give
a colorless solution. All volatiles were removed under reduced pressure
to give a colorless solid which was washed with pentane (2 × 1.5 mL)
and dried in vacuo. Yield: 112 mg (0.24 mmol) 67%.
4
Hz, JHH = 1.3 Hz, 4H, CH2−CHCH2), 3.65−3.69 (m, 8H, α-
2
3
4
THF), 4.85 (ddt, JHH = 2.0 Hz, JHH2 = 10.0 Hz, JH3H = 1.0 Hz, 2H,
CH2−CHCHcisHtrans), 4.97 (ddt, JHH = 2.0 Hz, JHH = 16.8 Hz,
4JHH = 1.4 Hz, 2H, CH2−CHCHcisHtrans), 6.12 (ddt, 3JHH = 8.3 Hz,
3JHH = 10.0 Hz, JHH = 16.8 Hz, 2H, CH2−CHCH2) ppm. 13C
3
1H NMR (400.1 MHz, THF-d8): δ = 1.34 (br d, 3JHH = 8.5 Hz, 6H,
2
3
NMR (100.6 MHz, THF-d8): δ = 20.62 (s, CH2−CHCH2), 26.53
(s, β-THF), 68.39 (s, α-THF), 114.05 (s, CH2−CHCH2), 123.93
CH2−CHCH2), 4.37 (br dd, JH3H = 2.2 Hz, JHH = 9.8 Hz, 3H,
CH2−CHCHcisHtrans), 4.51 (dm, JHH = 16.8 Hz, 3H, CH2−CH
CHcisHtrans), 5.89−6.00 (m, 3H, CH2−CH=CH2), 7.48−7.53 (m, 6H,
m-Ph), 7.58−7.63 (m, 3H, p-Ph), 7.67−7.73 (m, 6H, o-Ph) ppm.
3
(s, p-(C6H3Cl2)), 133.92 (q, JBC = 4.3 Hz, m-(C6H3Cl2)), 134.23 (q,
2JBC = 1.7 Hz, o-(C6H3Cl2)), 135.59 (s, CH2−CHCH2), 165.25
2258
dx.doi.org/10.1021/ic202293t | Inorg. Chem. 2012, 51, 2254−2262

Inorganic Chemistry
Article
1
(q, JBC = 49.7 Hz, ipso-(C6H3Cl2)) ppm. 11B NMR (128.4 MHz,
Reactivity toward Benzophenone. A solution of benzophenone
(for 1, 31 mg, 170 μmol; for 3, 10 mg, 55 μmol; for 5, 29 mg, 160
μmol) in THF-d8 (300 μL) was added to a solution of the gallium
compound (1, 15 mg, 57 μmol; 3, 27 mg, 28 μmol; 5, 11 mg, 40
μmol) in THF-d8 (300 μL). In each case a colorless solution was
obtained.
THF-d8): δ = −6.91 (s) ppm. Anal. Calcd for C38H38BCl8GaO2
(890.87 g/mol): C, 51.23; H, 4.30. Found: C, 50.08; H, 3.80.
K+[Ga(η1-C3H5)4]− (5). A solution of allylpotassium (20 mg, 0.25
mmol) in THF (600 μL) was added to a solution of 1 (66 mg, 0.25 mmol)
in THF (400 μL). The yellow reaction mixture turned colorless after a few
minutes. Upon addition of pentane (15 mL) a colorless oil precipitated.
The supernatant was decanted and the residue washed with pentane (4 ×
2 mL) to give a colorless solid, which was dried in vacuo for 2 h. Yield: 67
mg (0.25 mmol), quantitative.
Compound 1. Full conversion of 1 to insertion product 8 was
observed after ≤10 min.
1
[Ga(OC(C3H5)Ph2)3(THF)] (8). H NMR (400.1 MHz, THF-d8): δ
3
= 1.75−1.78 (m, 4H, β-THF), 3.26 (d, JHH = 6.8 Hz, 6H, CH2−
3
1H NMR (400.1 MHz, THF-d8): δ = 1.08 (br d, 3JHH = 8.5 Hz, 8H,
CHCH2), 3.60−3.63 (m, 4H, α-THF), 4.77 (dm, JHH = 10.3 Hz,
3
3H, CH2−CHCHcisHtrans), 4.87 (dm, JHH = 17.3 Hz, 3H, CH2−
2
3
CH2−CHCH2), 4.73 (br dd, JHH = 3.3 Hz, JHH = 10.0 Hz, 4H,
3
3
3
CHCHcisHtrans), 5.63 (ddt, JHH = 6.8 Hz, JHH = 10.3 Hz, JHH
=
CH2−CHCHcisHtrans), 5.03 (br dd, JHH = 3.3 Hz, JHH = 16.8 Hz,
2
3
4H, CH2−CHCHcisHtrans), 6.90 (ddt, 3JHH = 9.0 Hz, 3JHH = 10.0 Hz,
17.3 Hz, 3H, CH2−CHCH2) 7.08−7.12 (m, 6H, p-Ph), 7.16−7.20
(m, 12H, m-Ph), 7.36−7.39 (m, 12H, o-Ph) ppm. 13C NMR (100.6
MHz, THF-d8): δ = 26.53 (s, β-THF), 48.66 (s, CH2−CHCH2),
68.39 (s, α-THF), 81.54 (s, C−CH2−CHCH2), 116.50 (s, CH2−
CHCH2), 126.81 (s, p-Ph), 128.22 (s, m-Ph), 128.76 (s, o-Ph),
137.48 (s, CH2−CHCH2) 151.23 (s, ipso-Ph) ppm.
3JHH = 16.8 Hz, 4H, CH2−CHCH2) ppm. H NMR (400.1 MHz,
1
Py-h5/Py-d5(1:1)): δ = 2.05 (br s, 8H, CH2−CHCH2), 4.01 (br dd,
2JHH = 3.5 Hz, JHH = 10.0 Hz, 4H, CH2−CHCHcisHtrans), 4.24
3
(ddm, JHH = 3.5 Hz, JHH = 16.8 Hz, 4H, CH2−CHCHcisHtrans),
2
3
3
3
3
6.06 (ddt, JHH = 8.5 Hz, JHH = 10.0 Hz, JHH = 16.8 Hz, 4H, CH2−
CHCH2) ppm. 13C NMR (100.6 MHz, THF-d8): δ = 22.68 (br s,
CH2−CHCH2), 99.26 (s, CH2−CHCH2), 148.22 (s, CH2−CH
CH2) ppm. Anal. Calcd for C12H20GaK (273.11 g/mol): Ga, 25.53.
Found: Ga, 25.15.
Compound 3. Insertion of 1 equiv of benzophenone was detected
after ≤10 min to give 9. The second equivalent of benzophenone did
not react within 45 min, after which beginning polymerization of THF
was observed.
[Ga(η1-C3H5)(OC(C3H5)Ph2)(THF)2]+[B(C6F5)4]− (9). 1H NMR
[K(dibenzo-18-c-6)]+[Ga(η1-C3H5)4]− (6). Dibenzo-18-crown-6
(52 mg, 0.14 mmol) was added to a solution of 5 (39 mg, 0.14
mmol) in THF (1.5 mL). The reaction mixture was filtered. All
volatiles were removed from the filtrate under reduced pressure to give
a pale yellow oil. Upon addition of pentane (2 mL) a colorless solid
precipitated. The supernatant was decanted and the residue washed
with pentane (4 × 2 mL) to give a colorless solid which was dried in
vacuo. Yield: 86 mg, 0.14 mmol, quantitative.
3
(400.1 MHz, THF-d8): δ = 1.51 (dm, JHH = 8.3 Hz, 2H, Ga−
CH2−CHCH2), 1.76−1.79 (m, 8H, β-THF), 3.14 (br d, 3JHH = 7.0
Hz, 2H, C−CH2−CHCH2), 3.60−3.63 (m, 8H, α-THF), 4.83 (ddt,
2JHH = 1.6 Hz, JHH = 10.0 Hz, JHH = 1.0 Hz, 1H, Ga−CH2−CH
3
4
CHcisHtrans), 4.89 (ddt, JHH = 1.6 Hz, JHH = 16.8 Hz, JHH = 1.5 Hz,
2
3
4
1H, Ga−CH2−CHCHcisHtrans), 5.10 (dm, JHH = 10.2 Hz, 1H, C−
3
CH2−CHCHcisHtrans), 5.14 (dm, JHH = 17.2 Hz, 1H, C−CH2−
3
3
3
3
CHCHcisHtrans), 5.52 (ddt, JHH = 8.3 Hz, JHH = 10.0 Hz, JHH
=
=
1H NMR (400.1 MHz, THF-d8): δ = 1.10 (br s, 8H, CH2a,b−CH
CH2), 3.98−4.00 (m, 8H, O(CH2CH2)O), 4.02 (br s, 4H, CH2−
CHCHcisHtrans), 4.22 (br s, 4H, CH2−CHCHcisHtrans), 4.24−4.26
(m, 8H, O(CH2CH2)O), 6.02−6.13 (m, 4H, CH2−CHCH2), 6.93−
3
3
16.8 Hz, 1H, Ga−CH2−CHCH2), 5.78 (ddt, JHH = 7.0 Hz, JHH
3
10.2 Hz, JHH = 17.2 Hz, 1H, C−CH2−CHCH2), 7.22−7.27 (m,
2H, p-Ph), 7.30−7.35 (m, 4H, m-Ph), 7.40−7.43 (m, 4H, o-Ph) ppm.
Noncoordinate benzophenone was also detected. Reaction of 3 with 1
equiv of benzophenone under the conditions described above gives the
same spectrum without the resonances of noncoordinate benzophe-
none. 13C NMR (100.6 MHz, THF-d8): δ = 19.13 (s, Ga−CH2−
CHCH2), 26.49 (s, β-THF), 49.17 (s, C−CH2−CHCH2), 68.38
(s, α-THF), 81.09 (s, C−CH2−CHCH2), 115.83 (s, Ga−CH2−
CHCH2), 119.42 (s, C−CH2−CHCH2), 125.47 (br s, ipso-C6F5),
127.39 (s, o-Ph), 128.22 (s, p-Ph), 129.41 (s, m-Ph), 136.23 (s, Ga−
6.97 (m, 4H, Ph3,6), 7.01−7.05 (m, 4H, Ph4,5) ppm. H NMR (400.1
1
MHz, CD2Cl2): δ = 1.10 (br d, JHH = 8.1 Hz, 8H, CH2a,b−CH
3
3
CH2), 4.00−4.02 (m, 8H, O(CH2CH2)O), 4.07 (br d, JHH = 9.2 Hz,
4H, CH2−CHCHcisHtrans), 4.18−4.20 (m, 8H, O(CH2CH2)O),
4.25 (br d, JHH = 17.1 Hz, 4H, CH2−CHCHcisHtrans), 5.96−6.07
3
(m, 4H, CH2−CH=CH2), 6.90−6.95 (m, 4H, Ph3,6), 6.99−7.03 (m,
4H, Ph4,5) ppm. 13C NMR (100.6 MHz, THF-d8): δ = 21.74 (br s,
CH2−CHCH2), 68.49 (s, O(CH2CH2)O), 70.52 (s, O(CH2-
CH2)O), 99.29 (br s, CH2−CHCH2), 112.58 (s, Ph3,6), 122.46 (s,
Ph4,5), 148.26 (s, CH2−CHCH2, Ph1,2 (overlapped)) ppm. 13C
NMR (100.6 MHz, CD2Cl2): δ = 22.01 (br s, CH2−CHCH2), 67.43
(s, O(CH2CH2)O), 69.88 (s, O(CH2CH2)O), 99.78 (s, CH2−CH
CH2), 112.00 (s, Ph3,6), 122.43 (s, Ph4,5), 146.95 (s, Ph1,2), 147.59 (s,
CH2−CHCH2) ppm. Anal. Calcd for C32H44GaKO6 (537.42 g/mol):
Ga, 11.01. Found: Ga, 10.59.
1
CH2−CHCH2), 137.25 (dm, JCF = 244.5 Hz, m-C6F5), 138.91 (s,
1
C−CH2−CHCH2), 139.55 (dm, JCF = 245.4 Hz, p-C6F5), 149.30
1
(dm, JCF = 241.0 Hz, o-C6F5), 150.14 (s, ipso-Ph) ppm. Unreacted
benzophenone and small amounts of byproducts (presumably due to
polymerization of THF) were also detected. 11B NMR (128.4 MHz,
THF-d8): δ = −18.44 (s) ppm.
When the reaction was carried out in pyridine-d5 at ambient
1
temperature, no insertion product was detected by H NMR analysis
[PPh4]+[Ga(η1-C3H5)4]− (7). THF (2.0 mL) was added to a mixture
of 5 (99 mg, 0.36 mmol) and [PPh4]+Br− (152 mg, 0.36 mmol) to give
a suspension which was stirred at ambient temperature for 2 h. The
reaction mixture was filtered, and all volatiles were removed from
the orange filtrate under reduced pressure. The residue was washed
with pentane (3 × 2 mL) to yield an off-white solid, which was dried
in vacuo for 3 h. Yield: 169 mg, 0.29 mmol, 81%.
after a reaction time of more than 1 day. Insertion of 1 equiv of
benzophenone was observed after a reaction time of 6 days at 60 °C.
[Ga(η1-C3H5)(OC(C3H5)Ph2)(Py-d5)n]+[B(C6F5)4]−. 1H NMR
3
4
(400.1 MHz, Py-d5): δ = 1.97 (dt, JHH = 8.3 Hz, JHH = 1.1 Hz,
3
2H, Ga−CH2−CHCH2), 3.32 (br d, JHH = 6.8 Hz, 2H, C−CH2−
CHCH2), 4.87 (ddt, JHH = 1.8 Hz, 3JHH = 10.0 Hz, JHH = 1.0 Hz,
2
4
1H, Ga−CH2−CHCHcisHtrans), 4.97 (ddt, JHH = 2.0 Hz, JHH
=
2
3
1H NMR (400.1 MHz, THF-d8): δ = 1.07 (br s, 8H, CH2−CH
10.0 Hz, JHH = 1.0 Hz, 1H, C−CH2−CHCHcisHtrans), 4.99 (dm,
4
2
3
3JHH = 17.1 Hz, 1H, Ga−CH2−CHCHcisHtrans) 5.03 (dm, JHH
=
3
CH2), 3.97 (br dd, JHH = 2.8 Hz, JHH = 9.5 Hz, 4H, CH2−CH
CHcisHtrans), 4.21 (br d, JHH = 16.8 Hz, 4H, CH2−CHCHcisHtrans),
3
17.1 Hz, 1H, C−CH2−CHCHcisHtrans), 5.84 (ddt, JHH = 8.3 Hz,
3
3JHH = 10.0 Hz, 3JHH = 17.1 Hz, 1H, Ga−CH2−CHCH2), 5.90 (ddt,
5.98−6.09 (m, 4H, CH2−CHCH2), 7.74−7.82 (m, 16H, o-, m-Ph),
7.93−7.97 (m, 4H, p-Ph) ppm. 13C NMR (100.6 MHz, THF-d8): δ =
22.53 (br s, CH2−CHCH2), 99.26 (s, CH2−CHCH2), 119.30 (d,
1JCP = 90.2 Hz, ipso-Ph), 131.55 (d, 3JCP = 13.0 Hz, m-Ph), 135.84 (d,
3JHH = 6.8 Hz, JHH = 10.0 Hz, JHH = 17.1 Hz, 1H, C−CH2−CH
CH2), 7.26−7.33 (m, 6H, o-, p-Ph), 7.55−7.59 (m, 4H, m-Ph) ppm.
Noncoordinate THF (2 equiv) and 1 equiv of unreacted
benzophenone were also detected. 13C NMR (100.6 MHz, Py-d5):
δ = 17.77 (s, Ga−CH2−CHCH2), 48.82 (s, C−CH2−CHCH2),
80.91 (s, C−CH2−CHCH2), 114.77 (s, Ga−CH2−CHCH2),
118.85 (s, C−CH2−CHCH2), 125.71 (br s, ipso-C6F5), 127.58 (s, o-Ph),
3
3
2JCP = 10.4 Hz, m-Ph), 136.56 (d, JCP = 3.5 Hz, p-Ph), 148.28 (s,
4
CH2−CHCH2) ppm. 31P NMR (162.0 MHz, THF-d8): δ = 21.20
(s) ppm. Anal. Calcd for C36H40GaP (573.40 g/mol): Ga, 12.16.
Found: Ga, 12.40.
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127.86 (s, p-Ph), 129.13 (s, m-Ph), 134.94 (s, Ga−CH2−CHCH2),
139.31 (dm, 1JCF = 251.4 Hz, m-C6F5), 138.57 (s, C−CH2−CHCH2),
(s, Ga−CH2−CHCH2), 141.19 (s, C3-(NC9H7)), 141.94 (s, C3-
(NC9H7(C3H5))), 153.26 (s, C1-(NC9H7)) ppm.
1
[Ga(η1-C3H5)2(NC9H7)2]+[B(C6F5)4]− (12). H NMR (400.1 MHz,
1
1
137.44 (dm, JCF = 248.8 Hz, p-C6F5), 149.49 (dm, JCF = 241.0 Hz,
o-C6F5), 150.69 (s, ipso-Ph) ppm. Noncoordinate THF and unreacted
benzophenone were also detected.
3
4
4
THF-d8): δ = 2.25 (dt, JHH = 8.5 Hz, JHH = 1.0 Hz, JHH = 1.5 Hz,
2
3
4H, CH2−CHCH2), 4.74 (ddt, JHH = 2.0 Hz, JHH = 10.0 Hz,
4JHH = 1.0 Hz, 2H, CH2−CHCHcisHtrans), 4.92 (ddt, 2JHH = 2.0 Hz,
3JHH = 16.8 Hz, 4JHH = 1.5 Hz, 2H, CH2−CHCHcisHtrans), 6.09 (ddt,
3JHH = 8.5 Hz, 3JHH = 10.0 Hz, 3JHH = 16.8 Hz, 2H, CH2−CHCH2),
7.92 (ddd, 3JHH = 8.3 Hz, 3JHH = 7.1 Hz, 4JHH = 1.1 Hz, 2H, H7), 8.09
(ddd, 3JHH = 8.3 Hz, 3JHH = 7.1 Hz, 4JHH = 1.1 Hz, 2H, H6), 8.15 (br d,
3JHH = 8.3 Hz, 2H, H5), 8.23 (br d, 3JHH = 6.4 Hz, 2H, H4), 8.31 (br d,
Compound 5. After 53 h 2 equiv of benzophenone had been
consumed. The remaining 2 equiv of benzophenone did not undergo
insertion within a total reaction time of more than 9 days.
K+[Ga(η1-C3H5)2(OC(C3H5)Ph2)2]− (10). 1H NMR (400.1 MHz,
3
THF-d8): δ = 0.88 (dm, JHH = 8.5 Hz, 4H, Ga−CH2−CHCH2),
3.13 (dt, 3JHH = 6.8 Hz, 4JHH = 1.3 Hz, 4H, C−CH2−CHCH2), 4.31
2
3
3
3JHH = 8.3 Hz, 2H, H8), 8.41 (br d, JHH = 6.4 Hz, 2H, H3), 9.46 (s,
(br dd, JHH = 3.3 Hz, JHH = 10.0 Hz, 2H, Ga−CH2−CH
2
3
4
CHcisHtrans), 4.42 (ddt, JHH = 3.3 Hz, JHH = 16.9 Hz, JHH = 1.3 Hz,
2H, H1) ppm. Noncoordinate THF (2 equiv) was also detected. 13C
NMR (100.6 MHz, THF-d8): δ = 18.83 (s, Ga−CH2−CHCH2),
112.52 (s, Ga−CH2−CHCH2), 125.40 (br s, ipso-C6F5), 125.78 (s,
2H, Ga−CH2−CHCHcisHtrans), 4.83 (br dd, JHH = 2.5 Hz, JHH
=
2
3
10.3 Hz, 2H, C−CH2−CHCHcisHtrans), 4.97 (ddt, JHH = 2.5 Hz,
2
3JHH = 17.3 Hz, JHH = 1.5 Hz, 2H, C−CH2−CHCHcisHtrans), 5.75
4
C4), 128.09 (s, C5), 129.75 (s, C8a), 130.43 (s, C8), 131.44 (s, C7),
3
3
3
1
136.47 (s, C6), 137.18 (s, Ga−CH2−CHCH2), 137.32 (dm, JCF
=
=
(ddt, JHH = 6.8 Hz, JHH = 10.3 Hz, JHH = 17.3 Hz, 2H, C−CH2−
CH=CH2), 5.75 (ddt, JHH = 8.8 Hz, 3JHH = 10.0 Hz, 3JHH = 16.9 Hz,
3
243.6 Hz, m-C6F5), 138.82 (s, C4a), 138.97 (s, C3), 139.29 (dm, 1JCF
1
2H, Ga−CH2−CHCH2), 7.08−7.12 (m, 4H, p-Ph), 7.18−7.23 (m,
8H, m-Ph), 7.44−7.47 (m, 8H, o-Ph) ppm. Unreacted benzophenone
was also detected. 13C NMR (100.6 MHz, THF-d8): δ = 25.69 (s, Ga−
CH2−CHCH2), 49.81 (s, C−CH2−CHCH2), 80.50 (s, C−CH2−
CHCH2), 105.40 (s, Ga−CH2−CHCH2), 116.45 (s, C−CH2−
CHCH2), 126.48 (s, p-Ph), 128.29 (s, m-Ph), 128.62 129.41 (s, m-
Ph), 138.94 (s, C−CH2−CHCH2), 144.42 (s, Ga−CH2−CH
CH2), 152.71 (s, ipso-Ph) ppm. Unreacted benzophenone was also
detected.
245.4 Hz, p-C6F5), 149.34 (dm, JCF = 241.9 Hz, o-C6F5), 153.85 (s,
C1) ppm. Noncoordinate THF was also detected. 11B NMR (128.4
MHz, THF-d8): δ = −16.59 (s) ppm. 19F NMR (188.1 MHz, THF-
d8): δ = −129.15 (br s, m-C6F5), −161.35 (t, 3JFF = 20.5 Hz, p-C6F5),
3
−164.85 (t, JFF = 18.7 Hz, o-C6F5) ppm.
K+[Ga(η1-C3H5)3(NC9H7(C3H5))]− (13). 1H NMR (400.1 MHz,
3
THF-d8): δ = 1.26 (dm, JHH = 8.8 Hz, 6H, Ga−CH2−CHCH2),
2
3
3
4
1.98 (dddt, JHH = 12.8 Hz, JHH = 4.3 Hz, JHH = 8.0 Hz, JHH = 1.0
2
3
Hz, 1H, C−CHaHb−CHCH2), 2.59 (dddt, JHH = 12.8 Hz, JHH
=
6.7 Hz, JHH = 9.1 Hz, JHH = 1.2 Hz, 1H, C−CHaHb−CHCH2),
3
4
Reactivity toward Isoquinoline. A solution of isoquinoline (for
1, 19 mg, 0.15 mmol; for 3, 5 mg, 0.039 mmol; for 5, 10 mg, 0.077
mmol) in THF-d8 (300 μL) was added to a solution of the allylgallium
compound (1, 20 mg, 0.075 mmol; 3, 19 mg, 0.019 mmol; 5, 21 mg,
0.077 mmol) in THF (300 μL) to give an orange (in the case of 1) or
colorless solution (in the case of 3 and 5). The reaction was finished
after reaction times of t ≤ 10 min (in the case of 1 and 3) and t = 17 h
(in the case of 5), respectively.
4.19 (ddt, 2JHH = 3.3 Hz, 3JHH = 9.9 Hz, 4JHH = 0.8 Hz, 3H, Ga−CH2−
CHCHcisHtrans), 4.31 (dd, JHH = 4.3 Hz, JHH = 9.1 Hz, 1H, H1),
3
3
2
3
4
4.42 (ddt, JHH = 3.3 Hz, JHH = 16.8 Hz, JHH = 1.2 Hz, 3H, Ga−
CH2−CHCHcisHtrans), 4.72 (ddt, JHH = 2.8 Hz, JHH = 10.2 Hz,
4JHH = 1.0 Hz, 1H, C−CH2−CHCHcisHtrans), 4.74 (d, 3JHH = 6.3 Hz,
1H, H4), 4.75 (ddt, 2JHH = 2.8 Hz, 3JHH = 17.0 Hz, 4JHH = 1.3 Hz, 1H,
C−CH2−CHCHcisHtrans), 5.64 (dddd, 3JHH = 6.7 Hz, 3JHH = 8.0 Hz,
3JHH = 10.2 Hz, 3JHH = 17.0 Hz, 1H, C−CH2−CHCH2), 6.08 (ddt,
2
3
[Ga(η1-C3H5)2(NC9H7(C3H5))(NC9H7)] (11). 1H NMR (400.1
3
3JHH = 8.8 Hz, JHH = 9.9 Hz, JHH = 16.8 Hz, 3H, Ga−CH2−CH
3
3
MHz, THF-d8): δ = 1.73 (dm, JHH = 8.5 Hz, 4H, Ga−CH2−CH
CH2), (ddm, 3JHH = 6.8 Hz, 3JHH = 7.4 Hz, 2H, C−CH2−CHCH2),
4.46 (t, 3JHH = 6.8 Hz, 2H, H1-(NC9H7(C3H5))), 4.51 (ddt, 2JHH = 2.5
CH2), 6.47 (dd, 3JHH = 7.5 Hz, 4JHH = 1.3 Hz, 1H, H5), 6.51 (d, 3JHH
=
6.3 Hz, 1H, H3), 6.52 (ddd, JHH = 7.0 Hz, JHH = 7.3 Hz, JHH = 1.3
3
3
4
3
4
Hz, JHH = 10.0 Hz, JHH = 1.0 Hz, 2H, Ga−CH2−CHCHcisHtrans),
Hz, 1H, H7), 6.58 (dd, JHH = 7.0 Hz, JHH = 1.3 Hz, 1H, H8), 6.74
3
4
2
3
4
(ddd, 3JHH = 7.3 Hz, 3JHH = 7.5 Hz, 4JHH = 1.3 Hz, 1H, H6) ppm. 13
C
4.68 (ddt, JHH = 2.5 Hz, JHH = 16.8 Hz, JHH = 1.3 Hz, 2H, Ga−
CH2−CHCHcisHtrans), 4.88 (ddt, JHH = 2.5 Hz, JHH = 17.1 Hz,
2
3
NMR (100.6 MHz, THF-d8): δ = 22.24 (s, Ga−CH2−CHCH2),
40.43 (s, C−CH2−CHCH2), 62.25 (s, C1), 90.16 (s, C4), 102.44 (s,
Ga−CH2−CHCH2), 114.69 (s, C−CH2−CHCH2), 119.71 (s,
C5), 119.81 (s, C7), 126.09 (s, C6), 127.04 (s, C8), 127.92 (s, C8a),
138.47 (s, C4a), 139.22 (s, C−CH2−CHCH2), 146.16 (s, Ga−CH2−
CHCH2), 146.38 (s, C) ppm.
4JHH = 1.3 Hz, 1H, C−CH2−CHCHcisHtrans), 4.91 (br dd, 2JHH = 2.8
3
3
Hz, JHH = 10.0 Hz, 1H, C−CH2−CHCHcisHtrans), 5.35 (d, JHH
=
=
=
6.7 Hz, 1H, H4-(NC9H7(C3H5))), 5.76 (ddt, JHH = 7.4 Hz, JHH
3
3
10.0 Hz, 3JHH = 17.1 Hz, 1H, C−CH2−CHCH2), 6.04 (ddt, JHH
3
3
3
8.5 Hz, JHH = 10.0 Hz, JHH = 16.8 Hz, 2H, Ga−CH2−CHCH2),
6.55 (d, 3JHH = 6.7 Hz, 1H, H3-(NC9H7(C3H5))), 6.80 (dd, 3JHH = 7.4
Reactivity toward Quinoline. A solution of quinoline (10 mg,
0.077 mmol) in THF-d8 (300 μL) was added to a solution of the
allylgallium compound (1, 21 mg, 0.079 mmol; 3, 38 mg, 0.039 mmol)
in THF (300 μL) to give an orange (in the case of 1) or colorless
solution (in the case of 3), respectively.
4
3
Hz, JHH = 0.8 Hz, 1H, H5-(NC9H7(C3H5))), 6.84 (br d, JHH = 7.4
Hz, 1H, H8), 6.87 (ddd, JHH = 7.4 Hz, JHH = 8.7 Hz, JHH = 1.5 Hz,
3
3
4
1H, H7-(NC9H7(C3H5))), 7.05 (ddd, JHH = 7.4 Hz, JHH = 8.7 Hz,
3
3
4JHH = 1.5 Hz, 1H, H6-(NC9H7(C3H5))) 7.67 (ddd, JHH = 7.0 Hz,
3
1
[Ga(η1-C3H5)3(NC9H7)]. H NMR (400.1 MHz, THF-d8): δ = 1.51
3JHH = 8.0 Hz, 4JHH = 1.3 Hz, 1H, H7-(NC9H7)), 7.82 (ddd, 3JHH = 7.0
3
2
Hz, 3JHH = 8.3 Hz, 4JHH = 1.3 Hz, 1H, H6-(NC9H7)), 7.85 (br d, 3JHH
=
(d, JHH = 8.5 Hz, 6H, CH2−CHCH2), 4.43 (br dd, JHH = 2.3 Hz,
3JHH = 10.0 Hz, 3H, CH2−CHCHcisHtrans), 4.58 (br d,3JHH = 16.8
Hz, 3H, CH2−CHCHcisHtrans), 5.94−6.05 (m, 3H, CH2−CH
CH2), 7.50 (dd, 3JHH = 8.5 Hz, 4JHH = 4.4 Hz, 1H, H3), 7.59 (ddd, 3JHH
= 7.0 Hz, 3JHH = 8.1 Hz, 4JHH = 1.3 Hz, 1H, H6), 7.76 (ddd, 3JHH = 7.0
3
8.3 Hz, 1H, H8-(NC9H7)), 7.87 (br d, JHH = 6.0 Hz, 1H, H4-
(NC9H7)), 7.94 (br d, 3JHH = 8.0 Hz, 1H, H5-(NC9H7)), 8.31 (d, 3JHH
= 6.0 Hz, 1H, H3-(NC9H7)), 9.05 (s, 1H, H1-(NC9H7)) ppm.
Noncoordinate THF (1 equiv) was also detected. A second set of
signals (relative intensity: ca. 8%) was detected which was ascribed to
ligand scrambling. 13C NMR (100.6 MHz, THF-d8): δ = 19.37 (s, Ga−
CH2−CHCH2), 41.07 (s, C−CH2−CHCH2), 60.89 (s, C1-
(NC9H7(C3H5))), 98.11 (s, C4-(NC9H7(C3H5))), 108.91 (s, Ga−
CH2−CHCH2), 116.52 (s, C−CH2−CHCH2), 122.20 (s, C8-
(NC9H7(C3H5))), 123.14 (s, C4-(NC9H7)), 123.65 (s, C7-
(NC9H7(C3H5))), 126.80 (s, C5-(NC9H7(C3H5))), 127.60 (s, C6-
(NC9H7(C3H5))), 129.49 (s, C7-(NC9H7)), 129.53 (s, C8a-(NC9H7)),
129.59 (s, C8-(NC9H7(C3H5))), 129.83 (s, C8a-(NC9H7(C3H5))),
133.55 (s, C6-(NC9H7)), 136.03 (s, C4a-(NC9H7(C3H5))), 137.61
(s, C−CH2−CHCH2), 138.47 (s, C4a-(NC9H7)), 140.55
3
4
3
Hz, JHH = 8.6 Hz, JHH = 1.4 Hz, 1H, H7), 7.92 (dd, JHH = 8.1 Hz,
4JHH = 1.4 Hz, 1H, H5), 8.18 (br d, 3JHH = 8.6 Hz, 1H, H8), 8.34 (br d,
3JHH = 8.5 Hz, 1H, H4), 8.87 (dd, JHH = 4.4 Hz, JHH = 1.6 Hz, 1H,
H2) ppm. Noncoordinate THF (1 equiv) was also detected. 13C NMR
(100.6 MHz, THF-d8): δ = 21.69 (s, CH2−CHCH2), 107.12 (s,
CH2−CHCH2), 122.13 (s, C3), 127.79 (s, C6), 129.16 (s, C5),
129.48 (s, C8), 129.84 (s, C4a), 130.78 (s, C7), 138.38 (s, C4), 141.64
(s, CH2−CHCH2), 148.42 (s, C8a), 151.53 (s, C2) ppm.
Noncoordinate THF was also detected.
3
4
[Ga(η1-C3H5)2(NC9H7)2]+[B(C6F5)4]−. H NMR (400.1 MHz, THF-
d8): δ = 2.19 (br d, JHH = 7.3 Hz, CH2−CHCH2), 4.72 (br d,
1
3
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3
3JHH = 9.0 Hz, 2H, CH2−CHCHcisHtrans), 4.86 (br d, JHH = 16.8
Hz, 2H, CH2−CHCHcisHtrans), 5.93−6.05 (m, 2H, CH2−CH
CH2), 7.80 (br s, 2H, H8), 7.81 (br s, 2H, H4), 7.91−7.95 (br m, 2H,
D. M. P., Eds.; Elsevier: Oxford, 2007; Vol. 3. (g) Knochel, P.
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Angew. Chem. 2009, 121, 5118−5121. (b) Schlosser, M.; Desponds,
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Krische, M. J. Angew. Chem. 2009, 121, 36−48. (f) Denmark, S. E.; Fu,
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H6), 8.11 (br d, JHH = 8.8 Hz, 2H, H5), 8.17−8.21 (br m, 2H, H7),
3
8.78−8.85 (br m, 2H, H3), 8.96−8.98 (s, 2H, H2) ppm. Non-
coordinate THF (2 equiv) was also detected. 13C NMR (100.6 MHz,
THF-d8): δ = 21.82 (s, Ga−CH2−CHCH2), 113.08 (s, Ga−CH2−
CHCH2), 122.96 (s, C4), 124.88 (br s, ipso-C6F5), 125.59 (s, C4a),
125.83 (br s, C5), 129.66 (br s, C8), 130.72 (s, C7), 133.70 (br s, C6),
1
136.69 (s, Ga−CH2−CHCH2), 137.26 (dm, JCF = 244.5 Hz, m-
C6F5), 139.29 (dm, 1JCF = 244.5 Hz, p-C6F5), 143.76 (br s, C3), 145.50
(br s, C8a), 149.35 (dm, 1JCF = 244.5 Hz, o-C6F5), 152.15 (s, C2) ppm.
Noncoordinate THF was also detected. 11B NMR (128.4 MHz, THF-
d8): δ = −18.44 (s) ppm. 19F NMR (188.1 MHz, THF-d8): δ =
−129.16 (br s, m-C6F5), −161.29 (t, 3JFF = 20.3 Hz, p-C6F5), −164.80
3
(t, JFF = 18.3 Hz, o-C6F5) ppm.
Single Crystal X-ray Analysis. X-ray diffraction data were
collected on a Bruker CCD area-detector diffractometer with Mo
Kα radiation (graphite monochromator, λ = 0.710 73 Å) using ω
scans. The SMART program package was used for the data collection
and unit cell determination, processing of the raw frame data was
performed using SAINT, and absorption corrections were applied with
SADABS32a (4, 14) or MULABS32b (2, [4·THF], 6). The structures
were solved by direct methods and refined against F2 using all
reflections with the SHELXL-97 software as implemented in the
program system WinGX.33 The non-hydrogen atoms were refined
anisotropically; only the carbon atoms in disordered fragments were
refined with isotropic displacement parameters. All hydrogen atoms
were included in calculated positions.
ASSOCIATED CONTENT
■
S
* Supporting Information
Full crystallographic data, in CIF format, for compounds 2, 4,
[4·THF], 6, and 14; time conversion plots for reactions of 5
and 7 with benzophenone; and synthesis and characterization
of 14. This material is available free of charge via the Internet at
http://pubs.acs.org.
(5) Gren, C. K.; Hanusa, T. P.; Brennessel, W. W. Polyhedron 2006,
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(b) Dagorne, S.; Atwood, D. A. Chem. Rev. 2008, 108, 4037−4071.
(c) Zimmermann, M.; Anwander, R. Chem. Rev. 2010, 110, 6194−
6259.
AUTHOR INFORMATION
■
Corresponding Author
(7) (a) Han, Y.; Huang, Y.-Z.; Fang, L.; Tao, W. T. Synth. Commun.
1999, 29, 867−876. (b) Evans, W. J.; Anwander, R.; Doedens, R. J.;
Ziller, J. W. Angew. Chem., Int. Ed. 1994, 33, 1641−1644. (c) Dietrich,
*E-mail: jun.okuda@ac.rwth-aachen.de. Fax: +49 241 80 92644.
H. M.; Tornroos, K. W.; Herdtweck, E.; Anwander, R. Organometallics
̈
ACKNOWLEDGMENTS
■
2009, 28, 6739−6749. (d) Zimmermann, M.; Litlabø, R.; Tornroos,
̈
Financial support by the Deutsche Forschungsgemeinschaft is
gratefully acknowledged. C.L. thanks the Fonds der Chem-
K. W.; Anwander, R. Organometallics 2009, 28, 6646−6649. (e) Dietrich,
H. M.; Maichle-Mossmer, C.; Anwander, R. Dalton Trans. 2010, 39,
́
ischen Industrie for a Kekule scholarship.
5783−5785. (f) Michel, O.; Tornroos, K. W.; Maichle-Mossmer, C.;
̈
̈
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(8) During the decomposition of 1 in C6D6, the reaction mixture
remained a colorless solution; i.e., degradation pathways involving
formation of elemental Ga are unlikely. Decomposition due to
carbogallation and/or allyl coupling reactions is possible, but could not
unambiguously be proved.
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(19) On the basis of approximations according to the solid-angle
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due to their steric properties.
(20) In THF solutions of compounds 5 and 6, interactions of the
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counterions cannot be excluded.
(21) A bridging coordination mode of allyl ligands in [K(18-c-
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interaction could not be determined due to poor qualitiy of the
samples subjected to single crystal X-ray analysis, see ref 12.
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(25) When pyridine-d5 was used as a solvent, clean insertion of 1
equiv of benzophenone was observed, but the reaction was
substantially slower (for details see Experimenal Section).
(26) A similar trend has been observed for allylaluminum
compounds, see ref 10a.
(27) In reactions of allylgallium species with ketones reported in the
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(29) (a) Formation of side products is presumably due to ligand
scrambling (formation of [Ga(η1-C3H5)3−n(NC9H7(C3H5))n(L)]; n =
2, 3; L = neutral ligand) and/or due to 2,3-insertion of isoquinoline
(formation of regioisomer). (b) As a referee mentioned, it should be
pointed out that 11 and 13 were formed as racemic mixtures each.
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