Formation of Zn-Zn and Zn-Pd Bonded Complexes by Reactions of Terminal Zinc Hydrides with Pd(II) Species

Article abstract of DOI:10.1021/acs.inorgchem.9b02062

Divalent palladium-induced homocoupling of terminal zinc hydrides to zinc-zinc bonded complexes was achieved herein. Reactions of zinc hydrides [LZnH] (L = CH₃C(2,6-ⁱPr₂C₆H₃N)CHC(CH₃)(N(CH₂)_nCH₂PPh₂); 1a: n = 1; 1b: n = 2) with 0.5 equiv of allyl(cyclopentadienyl)palladium(II) afforded heterotrinuclear [Zn₂Pd] complexes 3 containing direct Zn-Zn and Zn-Pd bonds, with concomitant elimination of propylene and cyclopentadiene. Complexes 3 were also accessed by the reactions of zinc hydrides 1 with allylpalladium(II) chloride with release of propylene and hydrogen chloride. Treatment of zinc hydrides 1 with 1 equiv of allyl(cyclopentadienyl)palladium(II) gave Zn-Pd bonded complex 5 by elimination of propylene, which can be transformed into heterotrinuclear complex 3 by further reaction with one additional molar equivalent of zinc hydrides. Heterobimetallic Zn-Pd complex 5b was found to be an effective catalyst in the hydrosilylation of benzaldehyde and its derivatives. Reaction of 5b with silane reagent Ph₂SiH₂ produced [Pd₂Si₂H₂] complex 8 with cleavage of the Pd-Zn bond, which served as an initiating species in the catalytic reaction. Complexes 4b, 5, and 8 in this study were characterized by X-ray diffraction.

Full text of DOI:10.1021/acs.inorgchem.9b02062

Article
Cite This: Inorg. Chem. XXXX, XXX, XXX−XXX
pubs.acs.org/IC
Formation of Zn−Zn and Zn−Pd Bonded Complexes by Reactions of
Terminal Zinc Hydrides with Pd(II) Species
Shengjie Jiang, Min Chen, and Xin Xu*
Key Laboratory of Organic Synthesis of Jiangsu Province, College of Chemistry, Chemical Engineering and Materials Science,
Soochow University, Suzhou 215123, P. R. China
*
S Supporting Information
ABSTRACT: Divalent palladium-induced homocoupling of
terminal zinc hydrides to zinc−zinc bonded complexes was
achieved herein. Reactions of zinc hydrides [LZnH] (L =
i
CH C(2,6- Pr C H N)CHC(CH )(N(CH ) CH PPh ); 1a:
3
2
6
3
3
2 n
2
2
n = 1; 1b: n = 2) with 0.5 equiv of allyl(cyclopentadienyl)-
palladium(II) afforded heterotrinuclear [Zn Pd] complexes 3
2
containing direct Zn−Zn and Zn−Pd bonds, with concom-
itant elimination of propylene and cyclopentadiene. Com-
plexes 3 were also accessed by the reactions of zinc hydrides 1
with allylpalladium(II) chloride with release of propylene and
hydrogen chloride. Treatment of zinc hydrides 1 with 1 equiv
of allyl(cyclopentadienyl)palladium(II) gave Zn−Pd bonded
complex 5 by elimination of propylene, which can be
transformed into heterotrinuclear complex 3 by further reaction with one additional molar equivalent of zinc hydrides.
Heterobimetallic Zn−Pd complex 5b was found to be an effective catalyst in the hydrosilylation of benzaldehyde and its
derivatives. Reaction of 5b with silane reagent Ph SiH produced [Pd Si H ] complex 8 with cleavage of the Pd−Zn bond,
2
2
2
2
2
which served as an initiating species in the catalytic reaction. Complexes 4b, 5, and 8 in this study were characterized by X-ray
diffraction.
INTRODUCTION
transition metal (TM) complexes resulted in the diverse
formation of metal-rich complexes or clusters, in which either
the [ZnCp*] or [ZnZnCp*] fragment functioned as a type of
■
Homonuclear metal−metal bonded complexes are of funda-
mental interest in numerous areas of chemical science. The
study of such complexes has flourished during the past two
1
10
one-electron donor ligand at the TM centers. Additionally,
their research provided examples of various organozinc ligand
coordination modes, where the dizinc bond coordinated to the
decades and shed light on new insights into the nature of the
2
chemical bonds. One of the landmark advances in this area
2
TM in a η -fashion to form a heterotrinuclear triangular
was the discovery of the first covalent Zn(I)−Zn(I) bonded
11
5
[Zn M] (M = Cu or Ni) core structure. Because the low-
2
complex [(η -Cp*) Zn ] (Cp* = C Me ) by Carmona and co-
2
2
5
5
3
valent Zn−Zn bond is isolobal to a dihydrogen molecule, such
workers in 2004. They obtained this unusual low-valent dizinc
2
η -Zn -M complexes can be viewed as zinc congeners of
2
complex through the reductive coupling of [Cp* Zn] with
2
12,13
nonclassical dihydrogen complexes of transition metals.
ZnEt , albeit with a low isolated yield. Subsequently, the
2
In our previous work, a novel pathway for the formation of
Zn(I)−Zn(I) bonded complexes was developed. Electron-rich
TM palladium(0) species was used in the dehydrocoupling of
reaction was improved by adding 2 equiv of potassium hydride
as the reductant, which gave the identical dizinc compound in
4
a higher yield. Inspired by this seminal work, a variety of
2
terminal Zn(II) hydrides, resulting in the formation of a η -
Zn(I)−Zn(I) bonded complexes supported by versatile
ancillary ligands were prepared and characterized. The most
14
5
dizinc bonded complex of palladium (Scheme 1). Density
functional theory computation studies revealed that an
oxidative addition at the Pd(0) center possibly occurred to
afford Pd(II) dihydride 2, followed by reductive elimination to
finally afford a Zn−Zn bonded complex 3. Herein, the
reactions between Zn(II) hydrides with a 0.5 equimolar
equiv of Pd(II) species were further investigated, which
common synthetic approach to such complexes is by the
reductive coupling reaction of Zn(II) halides with alkali
6
metals or by a recently developed method using low-valent
7
8
metallic reductants, that is, Mg(I) and Re(I). Ligand
substitution reactions of the Carmona’s dizinc complex provide
an alternative pathway to the desired Zn(I)−Zn(I) bonded
9
produced identical heterotrinuclear [Zn Pd] complexes via
complex.
2
Furthermore, the reactivity of Zn(I)−Zn(I) bonded
complexes has also been investigated. Fischer, Frenking, and
Received: July 10, 2019
5
co-workers reported that reactions of [(η -Cp*) Zn ] with
2
2
©
XXXX American Chemical Society
A
DOI: 10.1021/acs.inorgchem.9b02062
Inorg. Chem. XXXX, XXX, XXX−XXX

Inorganic Chemistry
Article
14
Scheme 1. Pd(PPh ) -Induced Dehydrocoupling of Terminal Zn(II) Hydrides
3
4
Scheme 2. Reactions of Zinc Hydrides 1 with Palladium(II) Complexes
facile alkene eliminations. Well-defined heterobimetallic
intermediate complexes featuring direct Zn−Pd bonds were
observed to be effective catalysts for the hydrosilylation of
aldehyde substrates.
Information), which possibly indicated the elimination of
hydrogen chloride (HCl) during the course of the reaction.
Subsequently, HCl elimination was confirmed by the treatment
of complex 1b with dry HCl gas, which resulted in the
formation of complex 4b in 63% isolated yield (for details see
Experimental Section). Apparently, palladium(II) species are
RESULTS AND DISCUSSION
Reactions of Zinc Hydrides with Palladium(II)
Complexes. The reaction between Zn(II) hydride 1a with a
■
also applicable for the homocoupling of zinc hydrides to afford
2
heterotrinuclear η -Zn −Pd complexes as that of using
2
palladium(0) species. The only difference lies in the
0
.5 mol equiv of a commercially available Pd(II) reagent,
elimination products.
namely, allyl(cyclopentadienyl)palladium, in a C D solution,
6
6
1
31
It has been well-documented that the reactions of ZnR (R =
was initially performed in an NMR tube. Its H and P NMR
spectroscopic monitoring clearly indicated the formation of the
previously reported heterotrinuclear complex 3a. During the
2
alkyl or Cp) with TM hydrides served as a facile synthetic
strategy to form Zn-TM bonded complexes through the
1
5,16
1
elimination of RH.
However, the use of zinc hydride via
reaction, propylene [ H: δ = 5.72 (m, 1H, CH), 5.01 (dm, 1H,
17
oxidative cleavage to construct a Zn-TM bond is limited. To
gain more insights into the reactions, we next investigated the
reactions of zinc hydrides with Pd(II) reagent in a 1:1 molar
ratio. Monitoring the reaction of complex 1b with an
equimolar equivalent of (η -C H )Pd(η -Cp) gave a new
sharp resonance at δ 33.8 ppm in the P NMR spectrum and
CH ), 4.95 (dm, 1H, CH ), 1.55 (dt, 3H, CH ) ppm] and free
2
2
3
1
cyclopentadiene [ H: δ = 6.49 (m, 2H, CH), 6.29 (m, 2H,
CH), 2.69 (m, 2H, CH ) ppm] were detected as the
2
elimination products instead of H evolution, as in our
2
1
4
3
3
5
previous case. Accordingly, the reactions of 1 with (η -
C H )Pd(η -Cp) were scaled up in toluene to eventually afford
3
5
5
31
3
5
1
[
Zn Pd] complexes 3 in high isolated yields (3a: 77%; 3b:
signals attributed to propylene in the H NMR spectrum.
2
6
4%) (Scheme 2).
Subsequently, another widely used Pd(II) species, allylpalla-
Scaling up the reaction in toluene eventually produced
complex 5b as a yellow solid in 62% yield (Scheme 3),
which was comprehensively characterized by NMR spectros-
copy, elemental analysis, and single-crystal X-ray diffraction.
The molecular structure of 5b (Figure 1) exhibits a
heterobimetallic core featuring a Pd−Zn bond length of
2.373(8) Å, which is significantly shorter than those in
dium chloride, was also investigated for this homocoupling
reaction. Reaction of zinc hydride 1a with 0.25 mol equiv of
3
[
η -(C H )PdCl] in toluene successfully provided [Zn Pd]
3
5
2
2
complex 3a in 75% isolated yield (Scheme 2). During the
reaction, generation of propylene was clearly observed from
the in situ H NMR spectrum. Under analogous conditions,
the reaction of 1b with [η -(C H )PdCl] led to the isolations
1
heterotrinuclear complex 3 (ca. 2.50 Å) and comparable to the
3
18,10a,c
shortest Pd−Zn bond reported in the literature.
The
3
5
2
of heterotrinuclear complex 3b and zinc chloride 4b. Complex
b was fully characterized by multinuclear NMR spectroscopy
and X-ray diffraction (Figure S4 in the Supporting
coordination sphere of the palladium atom was completed by
5
1
4
the η -cyclopentadienyl [ H: δ = 5.70 (s, 5H, C H ) ppm]
5 5
ligand and by the PPh group on the pendant arm (Pd1−
2
B
DOI: 10.1021/acs.inorgchem.9b02062
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Scheme 3. Reactions of Zinc Hydrides 1 with an Equimolar
Equivalent of Allyl(cyclopentadienyl)palladium(II)
performed, which rapidly afforded the homocoupling product
3b with concomitant elimination of free cyclopentadiene
(
Scheme 4; for details, see the Experimental Section). Thus,
Pd(II)-induced dizinc bond formation occurred via a two-step
alkene elimination process.
Catalytic Application of the Heterobimetallic Zn−Pd
Complex in Hydrosilylation of Aldehydes. Bimetallic
catalysis has recently attracted considerable attention because
of the potential cooperativity and synergy between the two
different metal centers, which may offer an advantage over
19
existing monometallic systems in selectivity and activity.
Although a variety of well-defined TM complexes based on
20
organozinc metalloligands have been described, their use in
homogeneous catalysis is scarce. Very recently, Tauchert and
co-workers reported a palladium(0) complex supported by a Z-
type Zn(II)-based ligand, which displayed high activity in the
2
1
hydrosilylation of carbon dioxide. In addition, metal-
catalyzed hydrosilylation of carbonyl substrates using silanes
22
offers an efficient protocol for the reduction of aldehydes.
With the bimetallic Zn−Pd complex 5b in hand, this
compound was subsequently tested for the hydrosilylation of
aromatic aldehydes by using Ph SiH and PhSiH as reducing
2
2
3
reagents. Excitingly, 5b was observed to be efficient for the
hydrosilylation of benzaldehyde and its derivatives under mild
conditions with only a 1 mol % catalyst loading, with the
results summarized in Table 1. In all cases, hydrosilylation
1
Figure 1. Molecular structure of complex 5b. Hydrogen atoms are
omitted for clarity; displacement ellipsoids are drawn at the 30%
probability level. Selected bond lengths (Å) and angles (deg): Pd1−
reactions were first conducted in C D and monitored by H
6
6
NMR spectroscopy. After consumption of the starting
aldehydes, the reaction was quenched and treated with 10%
aqueous NaOH to afford the final alcohol products to
determine the respective yields. When using Ph SiH as the
Zn1 2.373(1), Pd1−P1 2.186(2), Pd1−Cp 2.039(3), Zn1−N1
centr
1
.962(5), Zn1−N2 1.961(5), N1−C2 1.306(7), C2−C3 1.414(8),
2
2
C3−C4 1.381(8), N2−C4 1.328(8), P1−Pd1−Zn1 86.8(1), N1−
Zn1−N2 97.0(2), N1−Zn1−Pd1 125.3(1), N2−Zn1−Pd1 137.7(2).
reductant, benzaldehyde (6a) was converted to benzyl alcohol
7a) in a 70% isolated yield after 6 h (entry 1). The reaction
was significantly improved by changing the silane reagent to
PhSiH , which resulted in a 86% yield of 7a after only 20 min,
(
Cpcentr 2.039(3) Å, Pd1−P1 2.186(2) Å). Notably, the
3
coordination geometry at the zinc center is observed to be
under similar conditions (entry 2). Benzaldehyde derivatives
featuring polar functional groups such as methoxyl (entry 3),
nitro (entry 4), and chloride (entry 5) were tolerated in the
reactions. The results show that compound with electron-
donating group is more reactive than compounds containing
electron-withdrawing substituents (entry 3 vs entries 4 and 5)
in the catalytic system herein. Reducing the amount of used
PdNN
planar tricoordinated (ΣZn1
= 360.0(5)°). The Zn···P
distance was found to be 3.135(2) Å, indicating a negligible
interaction. The analogous reaction of zinc hydride 1a with an
3
5
equimolar equivalent of (η -C H )Pd(η -Cp) also afforded the
3
5
bimetallic [ZnPd] complex 5a (Scheme 3), albeit with a low
isolated yield (36%) because of the simultaneous formation of
the [Zn Pd] product 3a. Multinuclear NMR spectroscopic
silane to 0.33 equiv of PhSiH required a prolonged reaction
time (12 h) to achieve a satisfactory yield (entry 6).
To gain more insights into the bimetallic Zn−Pd catalysis
herein, the stoichiometric reactions between complex 5b with
two types of silanes in toluene, at room temperature, were
2
3
3
1
data of 5a are provided in the Experimental Section ( P: δ =
3.6 ppm). The structure of complex 5a was also confirmed by
2
single-crystal X-ray diffraction and is depicted in the
Supporting Information (Figure S8, Pd1−Zn1 2.388(1) Å).
To examine whether bimetallic complex 5 could be
transformed into the final Zn−Zn bonded complex 3, the
reaction of complex 5b with 1 equiv of zinc hydride 1b was
performed. The reaction of 5b with PhSiH rapidly took place
3
to generate several unidentified complexes, which cannot be
successfully separated. However, treatment of 5b with an
Scheme 4. Reaction of Complex 5b with an Equimolar Equivalent of Zinc Hydride 1b
C
DOI: 10.1021/acs.inorgchem.9b02062
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Inorganic Chemistry
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a
Table 1. Catalytic Hydrosilylation of Aldehydes by using Bimetallic Zn−Pd Complex 5b
a
b
c
Reaction conditions: 0.80 mmol of aldehyde, 0.80 mmol of silane, C D as the solvent, room temperature. Isolated yield. 0.27 mmol of PhSiH
3
6
6
d
e
3
5
was used. 0.5 mol % 8 was used as a catalyst. (η -C H )Pd(η -Cp) (1 mol %, 8 μmol) was used as a catalyst, and conversion was determined by
3
5
1
f
3
5
H NMR spectroscopy. (η -C H )Pd(η -Cp) (1 mol %, 8 μmol) with an equimolar amount of PPh (1 mol %, 8 μmol) was used as catalyst, and
3
5
3
1
conversion was determined by H NMR spectroscopy.
Scheme 5. Reaction of Bimetallic Zn−Pd Complex 5b with an Equimolar Equivalent of Ph SiH2
2
D
DOI: 10.1021/acs.inorgchem.9b02062
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Inorganic Chemistry
Article
equimolar equivalent of Ph SiH2 led to isolation of the
ide, were able to mediate stoichiometric dehydrocoupling of
2
2
[
Pd Si ] complex 8 in high yield (84%) as a yellow crystalline
zinc hydrides to form heterotrinuclear η -Zn −Pd complexes
2
2
2
solid (Scheme 5). H evolution during the reaction process was
through eliminations of propylene, cyclopentadiene, or HCl.
During the course of the reaction, direct Zn−Zn and Zn−Pd
bonds were formed. Heterobimetallic Zn−Pd bonded
complexes were also accessed by the reactions of zinc hydrides
with 1 equiv of allyl(cyclopentadienyl)palladium(II) and were
confirmed as intermediates for the formation of heterotrinu-
2
observed. Single crystals of complex 8, suitable for the X-ray
crystal structure analysis, were grown from a mixture of toluene
and hexane solution at −30 °C. The molecular structure of the
C -symmetric complex 8 (Figure 2) contained a planar
2
clear [Zn Pd] complexes. Such metal−metal bond-forming
2
reactions most likely profit from the phosphine-containing β-
25
diketiminato ligands because of the strong phosphorus
affinity of the palladium metal ion. Our study herein not
only provides a facile synthetic strategy to Zn−Zn or Zn−Pd
bonded complexes but also gives an example by using well-
defined TM−Zn bimetallic complex in homogeneous catalysis.
Although the existence of the bimetallic effect currently
remains ambiguous, the complex herein exhibits higher activity
than that of its parent monometallic palladium complex.
Further reactivity of these Zn−Zn and Zn−Pd bonded
complexes, especially in multimetallic catalysis, is currently
underway in our laboratory.
Figure 2. Molecular structure of complex 8. Hydrogen atoms (except
Pd−H) are omitted for clarity; displacement ellipsoids are drawn at
the 30% probability level. Selected bond lengths (Å) and angles
EXPERIMENTAL SECTION
■
General Procedures. All experiments were performed under a
dry argon atmosphere using standard Schlenk techniques or in a
glovebox. Solvents (including deuterated solvents used for NMR)
were dried and distilled prior to use. NMR spectra were recorded on a
Bruker 400 MHz spectrometer. Chemical shifts were reported as δ
units with reference to the residual solvent resonance or an external
standard. The assignments of NMR data were supported by one-
dimensional (1D) and two-dimensional (2D) NMR experiments.
Elemental analysis data were recorded on a Carlo-Erba EA-1110
instrument. High-resolution mass spectrometry was measured with a
Bruker micrOTF-Q III. Allylpalladium(II) chloride dimer, PhSiH3,
Ph SiH , PhCHO, p-Cl-PhCHO, p-OMe-PhCHO, and p-NO −
(
deg): Si1−H1 1.66(3), Pd1−H1 1.69(3), Pd1−Pd1′ 2.710(1), Pd1−
Si1 2.326(1), Pd1−Si1′ 2.410 (1), Pd1−P1 2.304(1), Zn1−N1
1
2
.954(2), Zn1−N2 1.929(2), Zn1−C37 2.052(4), Zn1−C33
.433(5), N1−C2 1.343(4), C2−C3 1.392(4), C3−C4 1.406(4),
N2−C4 1.320(4), Pd1−Si1−H1 44.6(11), Pd1−H1−Si1 91.8(16).
[
(
Pd Si ] unit with two hydrides bridging the Pd−Si edges
2
2
Pd1−Si1 2.326(1) Å, Pd1−Si1′ 2.410(1) Å, Pd1−H1 1.69(3)
Å, Si1−H1 1.66(3) Å, Pd1−Pd1′ 2.710(1) Å), which is quite
similar to the previously reported dinuclear palladium
complexes possessing the [Pd Si ] motif by Osakada and co-
2
2
2
3
26
PhCHO were purchased from Strem or Adamas. η -(C H )PdCp
3
5
14
2
2
and zinc hydrides 1 were synthesized following the literature
procedures.
workers, where such complexes were obtained by the reactions
23,24
of Ph SiH with either simple Pd(0) or Pd(II) species.
Reaction of Zinc Hydride 1a with Allyl(cyclopentadienyl)-
2
2
3
5
palladium(II). (η -C H )Pd(η -Cp) (32 mg, 0.15 mmol) was added
During the course of the reaction herein, cleavage of the Zn−
3
5
to a solution of 1a (161 mg, 0.30 mmol) in 3 mL of toluene. After it
was stirred at 60 °C for 4 h, the volatiles were removed under vacuum,
and then the residue was washed with hexane (3 × 1 mL) to finally
give 3a as a yellow crystalline solid (139 mg, 77% yield).
Pd bond occurred, and the cyclopentadienyl ligand was
2
transferred to the zinc center exhibiting an η -coordinated
fashion (Zn1−C37 2.052(4) Å, Zn1−C33 2.433(5) Å) in the
solid state. The phosphine pendant arm remains bound to the
Reaction of Zinc Hydride 1b with Allyl(cyclopentadienyl)-
1
13
palladium center (Pd1−P1 2.304(1) Å). The H/ C NMR
palladium(II). Following the procedure described for 3a, reaction of
3
5
signals of cyclopentadienyl are at δ 6.22/107.7 ppm.
1b (165 mg, 0.30 mmol) with (η -C H )Pd(η -Cp) (32 mg, 0.15
3
5
1
Additionally, a broad signal in the H NMR spectrum at δ
mmol) gave 3b as a yellow crystalline solid (116 mg, 64% yield).
Reaction of Zinc Hydride 1a with Allylpalladium(II) Chloride.
2
.57 ppm attributed to the SiH moiety was also observed.
Subsequently, complex 8 was directly applied in the catalytic
3
[
(
(η -C H )PdCl] (37 mg, 0.10 mmol) was added to a solution of 1a
3
5
2
214 mg, 0.40 mmol) in 3 mL of toluene. The reaction mixture was
hydrosilylation of benzaldehyde under the same conditions and
demonstrated a similar result to that of the parent complex 5b
stirred at room temperature for 1 h. The volatiles were removed under
vacuum, and the residue was washed with hexane (3 × 1 mL) to
finally give 3a as a yellow solid (176 mg, 75% yield).
(
Table 1, entry 7 vs entry 1), supporting the [Pd Si H ]
2 2 2
complex as an initiating species in the hydrosilylation reaction.
Reaction of Zinc Hydride 1b with Allylpalladium(II) Chloride.
3
A control experiment, by using the starting materiel (η -
3
[
(η -C H )PdCl] (18 mg, 0.05 mmol) was added to a solution of 1b
3
5
2
5
C H )Pd(η -Cp) as a catalyst under our typical conditions,
(110 mg, 0.20 mmol) in 3 mL of toluene. After it stood at room
temperature for 1 h, the reaction solution was concentrated to ∼1 mL,
and then hexane (3 mL) was layered to give a mixture of complex 3b
and 4b as crystalline solids. The mixture was separated manually with
the aid of an optical microscope in a glovebox to finally gave 3b (36
mg, 30% yield) as yellow crystals and 4b (13 mg, 11% yield) as
colorless crystals.
3
5
was performed, and the catalytic activity dropped significantly
in comparison with that of the bimetallic complex 5b system
(Table 1, entry 8 vs entry 2). However, such a difference is still
insufficient to draw a solid conclusion toward the influence of
the bimetallic effect in the reaction at current stage.
Reaction of Zinc Hydride 1b with HCl Gas to Give 4b. Freshly
prepared hydrogen chloride gas was bubbled into a solution of 1b
(275 mg, 0.5 mmol) in 5 mL of toluene. The volatiles were removed
under vacuum, and the residue was washed with hexane (3 × 1 mL)
CONCLUSION
In summary, divalent palladium regents, such as allyl-
cyclopentadienyl)palladium(II) and allylpalladium(II) chlor-
■
(
E
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Article
1
to finally give 4b as a white solid (184 mg, 63% yield). H NMR (400
MHz, C D , 298 K): δ = 7.60 (m, 4H, o-Ph P), 7.10 (m, 2H, m-NAr),
7
Preparation of Complex 8. Ph SiH (46 mg, 0.25 mmol) was
2
2
added to a solution of 5b (180 mg, 0.25 mmol) in 3 mL of toluene.
After it stirred at room temperature for 4 h, the volatiles were
removed under vacuum. The residue was washed with hexane (3 × 1
mL) to finally give 8 as yellow crystalline solid (190 mg, 84% yield).
Crystals suitable for the X-ray crystal structure analysis were grown
6
6
2
.09 (m, 1H, p-NAr), 7.05 (m, 4H, m-Ph P), 7.03 (m, 2H, p-Ph P),
2
2
4
.66 (s, 1H, MeC(N)CH), 3.51 (m, 2H, NCH ), 3.50 (m, 2H,
ArCHMe ), 2.24 (m, 2H, PCH ), 1.72 (s, 3H, MeC), 1.48 (s, 3H,
2
2
2
MeC), 1.26 (overlapped with NArCHMe , NCH CH ), 1.21 (m, 6H,
2
2
2
3
13
1
1
NArCHMe ), 1.15 (d, J = 6.9 Hz, 6H, ArCHMe2). C{ H} NMR
from a layered toluene/hexane (v/v: 1:2) solution at −30 °C. H
2
HH
(
101 MHz, C D , 298 K): δ = 167.2 (MeC), 167.1 (MeC), 144.8 (i-
NAr), 143.1 (o-NAr), 134.0 (i-Ph P), 134.0 (d, J = 12.9 Hz, o-
NMR (400 MHz, C
8H, o-Ph
(m, 12H, m, p-Ph
3.04 (m, 4H, ArCHMe
.93 (m, 4H, PCH ), 1.57 (s, 6H, MeC), 1.48 (s, 6H, MeC), 1.38 (m,
6
D , 298 K): δ = 7.66 (m, 8H, o-Ph Si), 7.45 (m,
6
2
6
6
2
P), 7.17 (m, 12H, m, p-Ph
P), 6.22 (s, 10H, Cp), 4.54 (s, 2H, MeC(N)CH),
), 2.64 (m, 4H, NCH ), 2.57 (br, 2H, SiH),
Si), 7.12 (m, 6H, m, p-NAr), 6.96
2
PC
2
2
3
Ph P), 130.6 (p-Ph P), 128.9 (d, J = 9.1 Hz, m-Ph P), 125.9 (p-
2
2
2
PC
2
NAr), 123.9 (m-NAr), 94.6 (MeC(N)CH), 50.8 (NCH ), 29.0 (d,
JPC = 9.1 Hz, PCH ), 28.5 (ArCHMe ), 26.4 (NCH CH ), 25.0
ArCHMe ), 24.2 (ArCHMe ), 24.0 (MeC), 20.7 (MeC). P{ H}
NMR (162 MHz, C D , 298 K): δ = −17.3. Anal. Calcd for
C H ClN PZn: C, 65.76; H, 6.90; N, 4.79. Found: C, 65.97; H,
2
2
2
1
1
2
2
2
2
2
3
3
1
1
4H, NCH CH ), 1.22 (d, J = 6.8 Hz, 12H, ArCHMe ), 1.09 (d,
(
2
2
HH
2
2
2
3
13
1
JHH = 6.8 Hz, 12H, ArCHMe2). C{ H} NMR (101 MHz, C D ,
6
6
6
6
2
98 K): δ = 169.8 (MeC), 167.1 (MeC), 144.0 (i-NAr), 143.6 (i-
32
40
2
Ph Si), 142.3 (o-NAr), not observed (n.o.) (i-Ph P), 136.3 (o-Ph Si),
7
.23; N, 4.54%.
2
2
2
3
5
133.5 (o-Ph P), 129.6 (o-Ph P), 128.5 (overlapped with solvent, m-
Preparation of 5a. (η -C H )Pd(η -Cp) (96 mg, 0.45 mmol) was
2 2
3
5
Ph P), 128.2 (overlapped with solvent, m-Ph Si), 127.9 (overlapped
added to a solution of 1a (241 mg, 0.45 mmol) in 5 mL of toluene.
After it stirred at room temperature for 2 h, the volatiles were
removed by vacuum. The residue was recrystallized in toluene (1 mL)
at −30 °C to finally give 5a as a yellow crystalline solid (114 mg, 36%
yield). Crystals suitable for the X-ray crystal structure analysis were
grown from a layered toluene/hexane (v/v: 1:2) solution at −30 °C.
Note: During the reaction, heterotrinuclear complex 3a was
simultaneously generated, which led to a low yield of 5a. H NMR
400 MHz, C D , 298 K): δ = 7.64 (m, 4H, o-Ph P), 7.24 (m, 3H, m,
p-NAr), 7.08 (m, 4H, m-Ph P), 7.03 (m, 2H, p-Ph P), 5.58 (s, 5H,
Cp), 4.77 (s, 1H, MeC(N)CH), 3.26 (m, 2H, NCH ), 3.24 (m, 2H,
2
2
with solvent, p-Ph P), 126.3 (p-NAr), 124.0 (m-NAr), 107.7 (Cp),
2
1
1
9
2
2
5.3 (MeC(N)CH), 51.9 (NCH ) , 28.4 (ArCHMe ), 28.3 (PCH ) ,
2 2 2
7.6 (NCH CH ), 24.2 (ArCHMe ), 24.1 (ArCHMe ), 23.5 (MeC),
2
2
2
2
1
1
13
31
1
1.6 (MeC) [ from the H, C GHSQC experiment]. P{ H}
NMR(162 MHz, C D , 298 K): δ = 19.9. Anal. Calcd for
6
6
C H N P Pd Si Zn : C, 65.11; H, 6.25; N, 3.10. Found: C,
98 112
4
2
2
2
2
1
65.78; H, 6.32; N, 2.94%.
General Procedure for Hydrosilylation Reactions. In the glove-
(
6
6
2
box, a benzene-d solution of silane (0.80 mmol) and aldehyde (0.80
6
2
2
mmol) was added to a vial containing 5.8 mg (0.008 mmol) of 5b.
The resulting solution was transferred into a J. Young tube, where it
remained at ambient temperature. The progress of the reaction was
2
3
ArCHMe ), 2.24 (m, 2H, PCH ), 1.73 (s, 3H, MeC), 1.52 (d, J =
2
2
HH
3
6
6
(
3
2
.9 Hz, 6H, ArCHMe ), 1.49 (s, 3H, MeC), 1.19 (d, J = 6.9 Hz,
2 HH
1
H, ArCHMe2). 13C{ H} NMR (101 MHz, C D , 298 K): δ = 167.3
1
monitored by H NMR spectroscopy. When the reaction was
6
6
1
completed, the mixture was treated with a 10% aqueous solution of
NaOH (1 mL) with vigorous stirring at room temperature overnight.
MeC), 166.1 (MeC), 145.7 (i-NAr), 142.2 (o-NAr), 140.7 (d, J
9.4 Hz, i-Ph P), 133.2 (d, J = 13.9 Hz, o-Ph P), 129.5 (d, J
=
=
PC
2
4
2 PC 2
PC
The organic product was extracted with Et O (3 × 15 mL), dried over
2
.2 Hz, p-Ph P), 128.2 (overlapped with solvent, m-Ph P), 126.4 (p-
2
2
2
anhydrous MgSO , and concentrated under vacuum. The alcohol
4
NAr), 124.2 (m-NAr), 96.2 (MeC(N)CH), 93.6 (Cp), 47.3 (d, J
=
PC
1
product was further purified by silica column chromatography (with
petroleum/ethyl acetate 10/1 as eluent).
3
.1 Hz, NCH ), 35.4 (d, J = 34.9 Hz, PCH ), 28.7 (ArCHMe ),
2 PC 2 2
2
4.6 (ArCHMe ), 24.0 (MeC), 23.9 (ArCHMe ), 22.2 (MeC).
P{ H} NMR (162 MHz, C D , 298 K): δ = 23.6. Anal. Calcd for
C H N PPdZn: C, 61.20; H, 6.13; N, 3.97. Found: C, 61.39; H,
2
2
3
1
1
6
6
ASSOCIATED CONTENT
Supporting Information
The Supporting Information is available free of charge on the
ACS Publications website at DOI: 10.1021/acs.inorg-
chem.9b02062.
■
36
43
2
*
S
6
.04; N, 3.64%.
3
5
Preparation of 5b. (η -C H )Pd(η -Cp) (106 mg, 0.50 mmol) was
3
5
added to a solution of 1b (275 mg, 0.50 mmol) in 5 mL of toluene.
After it stirred at room temperature for 0.5 h, the volatiles were
removed under vacuum. The residue was washed with hexane (3 × 1
mL) to finally give 5b as a yellow crystalline solid (223 mg, 62%
yield). Crystals suitable for the X-ray crystal structure analysis were
grown from a layered toluene/hexane (v/v: 1:2) solution at −30 °C.
Characterization data and NMR spectra of new
complexes (PDF)
Accession Codes
1
H NMR (400 MHz, C D , 298 K): δ = 7.66 (m, 4H, o-Ph P), 7.19
6
6
2
CCDC 1939594−1939597 contain the supplementary crys-
tallographic data for this paper. These data can be obtained
free of charge via www.ccdc.cam.ac.uk/data_request/cif, or by
emailing data_request@ccdc.cam.ac.uk, or by contacting The
Cambridge Crystallographic Data Centre, 12 Union Road,
Cambridge CB21EZ, UK; fax: + 44 1223 336033.
(
m, 3H, m, p-NAr), 7.08 (m, 4H, m-Ph P), 7.03 (m, 2H, p-Ph P),
2
2
5
3
1
6
.70 (s, 5H, Cp), 4.77 (s, 1H, MeC(N)CH), 3.38 (m, 2H, NCH2),
.25 (m, 2H, ArCHMe ), 2.09 (m, 2H, PCH ), 1.73 (s, 3H, MeC),
2
2
3
.65 (s, 3H, MeC), 1.62 (m, 2H, NCH CH ), 1.32 (d, J = 6.9 Hz,
2
2
HH
3
13
1
H, ArCHMe ), 1.18 (d, J = 6.9 Hz, 6H, ArCHMe2). C{ H}
NMR (101 MHz, C D , 298 K): δ = 167.8 (MeC), 166.0 (MeC),
2
HH
6
6
1
1
1
1
45.4 (i-NAr), 142.2 (o-NAr), 140.1 (d, J = 37.5 Hz, i-Ph P),
PC 2
2
4
33.0 (d, J = 14.1 Hz, o-Ph P), 129.2 (d, J = 2.2 Hz, p-Ph P),
28.0 (overlapped with solvent, m-Ph P), 126.2 (p-NAr), 124.1 (m-
NAr), 96.3 (MeC(N)CH), 93.2 (Cp), 48.0 (d, J = 3.9 Hz, NCH2),
AUTHOR INFORMATION
Corresponding Author
E-mail: xinxu@suda.edu.cn.
PC
2
PC
2
■
2
3
PC
*
1
3
2
1.1 (d, J = 30.9 Hz, PCH ), 28.7 (ArCHMe ), 26.6 (NCH CH ),
PC 2 2 2 2
ORCID
4.4 (ArCHMe ), 24.0 (ArCHMe ), 23.9 (MeC), 21.3 (MeC).
P{ H} NMR (162 MHz, C D , 298 K): δ = 33.8. Anal. Calcd for
C H N PPdZn: C, 61.68; H, 6.30; N, 3.89. Found: C, 61.73; H,
2
2
31
1
Xin Xu: 0000-0003-2426-9816
Notes
The authors declare no competing financial interest.
6
6
37
45
2
6
.25; N, 3.58%.
Reaction of Complex 5b with 1 Equiv of Zinc Hydride 1b.
Complex 1b (55 mg, 0.10 mmol) was added to a solution of 5b (72
mg, 0.10 mmol) in 3 mL of toluene. The reaction mixture was stirred
at 60 °C for 4 h. The volatiles were removed under vacuum, and the
residue was washed with hexane (3 × 1 mL) to finally give 3b as a
yellow crystalline solid (72 mg, 59% yield).
ACKNOWLEDGMENTS
■
This work was supported by the National Natural Science
Foundation of China (21871204), 1000-Youth Talents Plan,
the Priority Academic Program Development of Jiangsu
F
DOI: 10.1021/acs.inorgchem.9b02062
Inorg. Chem. XXXX, XXX, XXX−XXX

Inorganic Chemistry
Article
Higher Education Institutions, and the project of scientific and
technologic infrastructure of Suzhou (SZS201708).
Zn-Zn Bond. Angew. Chem., Int. Ed. 2009, 48, 807−810. (c) Schulz,
S.; Schuchmann, D.; Krossing, I.; Himmel, D.; Blaser, D.; Boese, R.
̈
+
Structural Characterization of a Base-Stabilized [Zn ] Cation.
2
2
Angew. Chem., Int. Ed. 2009, 48, 5748−5751. (d) Schulz, S.;
Gondzik, S.; Schuchmann, D.; Westphal, U.; Dobrzycki, L.; Boese,
R.; Harder, S. Reactions of Dizincocene with Sterically Demanding
Bis(iminodi(phenyl)phosphorano)methanes. Chem. Commun. 2010,
REFERENCES
■
(
1) (a) Cotton, F. A.; Murillo, C. A.; Walton, R. A. Multiple Bonds
Between Metal Atoms, 3rd ed.; Springer: Berlin, Germany, 2005.
b) Liddle, S. T. Molecular Metal-Metal Bonds. Compounds, Synthesis
Properties; Wiley-VCH: Weinheim, Germany, 2015.
2) (a) Li, X.-W.; Pennington, W. T.; Robinson, G. H. A Metallic
(
́
6, 7757−7759. (e) Carrasco, M.; Peloso, R.; Rodríguez, A.; Alvarez,
4
E.; Maya, C.; Carmona, E. Zn-Zn-Bonded Compounds that Contain
(
Monoanionic Oxygen-Donor Ligands. Chem. - Eur. J. 2010, 16,
System with Aromatic Character. Synthesis and Molecular Structure
9
754−9757. (f) Nayek, H. P.; Luhl, A.; Schulz, S.; Koppe, R.; Roesky,
̈
̈
of Na [(Mes C H )Ga] (Mes = 2,4,6-Me C H ): The First Cyclo-
2
2
6
3
3
3
6
2
P. W. Aminotroponiminatozinc(I) Complexes: Syntheses and
gallane. J. Am. Chem. Soc. 1995, 117, 7578−7579. (b) Nguyen, T.;
Sutton, A. D.; Brynda, M.; Fettinger, J. C.; Long, G. J.; Power, P. P.
Synthesis of a Stable Compound with Fivefold Bonding Between Two
Chromium(I) Centers. Science 2005, 310, 844−847. (c) Green, S. P.;
Jones, C.; Stasch, A. Stable Magnesium(I) Compounds with Mg-Mg
Bonds. Science 2007, 318, 1754−1757. (d) Tsai, Y.-C.; Lin, Y.-M.; Yu,
J.-S. K.; Hwang, J.-K. A Three-Coordinate and Quadruply Bonded
Mo-Mo Complex. J. Am. Chem. Soc. 2006, 128, 13980−13981.
3) Resa, I.; Carmona, E.; Gutierrez-Puebla, E.; Monge, A.
Decamethyldizincocene, a Stable Compound of Zn(I) with a Zn-Zn
Bond. Science 2004, 305, 1136−1138.
4) Grirrane, A.; Resa, I.; Rodriguez, A.; Carmona, E.; Alvarez, E.;
Gutierrez-Puebla, E.; Monge, A.; Galindo, A.; del Río, D.; Andersen,
R. A. Zinc-Zinc Bonded Zincocene Structures. Synthesis and
Characterization of Zn (η -C Me ) and Zn (η -C Me Et) . J. Am.
Chem. Soc. 2007, 129, 693−703.
5) (a) Grirrane, A.; Resa, I.; Rodríguez, A.; Carmona, E. Synthesis
Spectroscopic Analyses. Chem. - Eur. J. 2011, 17, 1773−1777.
(10) (a) Bollermann, T.; Freitag, K.; Gemel, C.; Seidel, R. W.; von
Hopffgarten, M.; Frenking, G.; Fischer, R. A. The Reactivity of
Zn Cp* ]: Trapping Monovalent {CZnZnCp*} in the Metal-Rich
[
2
2
Compounds [(Pd,Pt)(GaCp*) (ZnCp*) (ZnZnCp*) ] (a = 0, 2).
a
4‑a
4‑a
Angew. Chem., Int. Ed. 2011, 50, 772−776. (b) Bollermann, T.;
Freitag, K.; Gemel, C.; Molon, M.; Seidel, R. W.; von Hopffgarten,
M.; Jerabek, P.; Frenking, G.; Fischer, R. A. The Rich Chemistry of
(
[
Zn Cp* ]: Trapping Three Different Types of Zinc Ligands in the
2 2
PdZn Complex [Pd(ZnCp*) (ZnMe) {Zn(tmeda)}]. Inorg. Chem.
7
4
2
2
011, 50, 10486−10492. (c) Bollermann, T.; Freitag, K.; Gemel, C.;
(
Seidel, R. W.; Fischer, R. A. Reactivity of [Zn Cp* ] toward
2
2
Transition-Metal Complexes: Synthesis and Characterization of
5
5
[Cp*M(ZnCp*) ] (M = Ni, Pd, Pt). Organometallics 2011, 30,
3
2
5
5
2
2
5
4
2
4
123−4127. (d) Freitag, K.; Banh, H.; Gemel, C.; Seidel, R. W.;
Kahlal, S.; Saillard, J.-Y.; Fischer, R. A. Molecular Brass: Cu Zn , a
4
4
(
5
Ligand Protected Superatom Cluster. Chem. Commun. 2014, 50,
8681−8684.
and Structural Characterization of Dizincocenes Zn (η -C Me ) and
2
5
5 2
5
Zn (η -C Me Et) . Coord. Chem. Rev. 2008, 252, 1532−1539.
2
5
4
2
(11) (a) Freitag, K.; Gemel, C.; Jerabek, P.; Oppel, I. M.; Seidel, R.
(
b) Carmona, E.; Galindo, A. Direct Bonds Between Metal Atoms:
W.; Frenking, G.; Banh, H.; Dilchert, K.; Fischer, R. A. The σ-
Zn, Cd, and Hg Compounds with Metal-Metal Bonds. Angew. Chem.,
Int. Ed. 2008, 47, 6526−6536. (c) Li, T.; Schulz, S.; Roesky, P. W.
Synthesis, Reactivity and Applications of Zinc-Zinc Bonded
Complexes. Chem. Soc. Rev. 2012, 41, 3759−3771.
6) Selected examples: (a) Wang, Y.; Quillian, B.; Wei, P.; Wang, H.;
Yang, X.-J.; Xie, Y.; King, R. B.; Schleyer, P. v. R.; Schaefer III, H. F.;
Robinson, G. H. On the Chemistry of Zn-Zn Bonds, RZn-ZnR (R =
+
Aromatic Clusters [Zn3] and [Zn Cu]: Embryonic Brass. Angew.
2
Chem., Int. Ed. 2015, 54, 4370−4374. (b) Freitag, K.; Molon, M.;
Jerabek, P.; Dilchert, K.; Rosler, C.; Seidel, R. W.; Gemel, C.;
̈
Frenking, G.; Fischer, R. A. Zn···Zn Interactions at Nickel and
Palladium Centers. Chem. Sci. 2016, 7, 6413−6421. (c) Banh, H.;
(
Hornung, J.; Kratz, T.; Gemel, C.; Pothig, A.; Gam, F.; Kahlal, S.;
̈
Saillard, J.-Y.; Fischer, R. A. Embryonic Brass: Pseudo Two Electron
[
{(2,6-Pri C H )N(Me)C} CH]): Synthesis, Structure, and Compu-
2 6 3 2
Cu/Zn Clusters. Chem. Sci. 2018, 9, 8906−8913.
tations. J. Am. Chem. Soc. 2005, 127, 11944−11945. (b) Zhu, Z.;
Wright, R. J.; Olmstead, M. M.; Rivard, E.; Brynda, M.; Power, P. P. A
Zinc-Zinc-Bonded Compound and Its Derivatives Bridged by One or
Two Hydrogen Atoms: A New Type of Zn-Zn Bonding. Angew.
Chem., Int. Ed. 2006, 45, 5807−5810. (c) Fedushkin, I. L.; Skatova, A.
A.; Ketkov, S. Y.; Eremenko, O. V.; Piskunov, A. V.; Fukin, G. K.
(12) Kubas, G. J. Activation of Dihydrogen and Coordination of
Molecular H on Transition Metals. J. Organomet. Chem. 2014, 751,
2
3
(
3−49.
13) Ayala, R.; Carmona, E.; Galindo, A. The Dizinc Bond as a
Ligand: A Computational Study of Elongated Dizinc Bonds. Inorg.
Chim. Acta 2018, 470, 197−205.
[
(dpp-Bian)Zn-Zn(dpp-Bian)]: A Zinc-Zinc-Bonded Compound
Supported by Radical-Anionic Ligands. Angew. Chem., Int. Ed. 2007,
(14) Chen, M.; Jiang, S.; Maron, L.; Xu, X. Transition Metal-
Induced Dehydrogenative Coupling of Zinc Hydrides. Dalton Trans
019, 48, 1931−1935.
15) (a) Budzelaar, P. H. M.; Boersma, J.; van der Kerk, G. J. M.;
Spek, A. L.; Duisenberg, A. J. M. Cyclopentadienylzinc-Transition
Metal Compounds. Structure of (C H Zn) Co(C H )P(C Hs) .
Inorg. Chem. 1982, 21, 3777−3780. (b) Budzelaar, P. H. M.; den
Haan, K. H.; Boersma, J.; van der Kerk, G. J. M.; Spek, A. L. Reaction
4
6, 4302−4305. (d) Zhu, Z.; Brynda, M.; Wright, R. J.; Fischer, R. C.;
2
(
Merrill, W. A.; Rivard, E.; Wolf, R.; Fettinger, J. C.; Olmstead, M. M.;
Power, P. P. Synthesis and Characterization of the Homologous M-M
Bonded Series Ar’MMAr’ (M = Zn, Cd, or Hg; Ar’ = C H -2,6-
6
3
i
(
C H -2,6-Pr ) ) and Related Arylmetal Halides and Hydride
5
5
2
5
5
6
3
6
3
2 2
Species. J. Am. Chem. Soc. 2007, 129, 10847−10857. (e) Yang, X.-
J.; Yu, J.; Liu, Y.; Xie, Y.; Schaefer, H. F.; Liang, Y.; Wu, B. A New
Zinc-Zinc-bonded Compound with a Dianionic α-Diimine Ligand:
Synthesis and Structure of [Na(THF) ] ·[LZn-ZnL] (L =
o f ( C
(C NbH
H
)
2
N b H
ZnC H . Organometallics 1984, 3, 156−159. (c) Budze-
5 5
w i t h ( C H ) Z n - S t r u c t u r e o f
5
5
2
3
5 5 2
H
)
5
2
2
5
2
i
2‑
[
(2,6- Pr C H )N(Me)C] ). Chem. Commun. 2007, 2363−2365.
laar, P. H. M.; van der Zeijden, A. A. H.; Boersma, J.; van der Kerk, G.
J. M.; Spek, A. L.; Duisenberg, A. J. M. Tantalum-Zinc Compounds-
2
6
3
2
(
7) Hicks, J.; Underhill, E. J.; Kefalidis, C. E.; Maron, L.; Jones, C. A
Mixed-Valence Tri-Zinc Complex, [LZnZnZnL] (L = Bulky Amide),
Bearing a Linear Chain of Two-Coordinate Zinc Atoms. Angew.
Chem., Int. Ed. 2015, 54, 10000−10004.
Structure of (CH C H ) TaH(ZnC H ) . Organometallics 1984, 3,
3 5 4 2 5 5 2
159−163.
(16) (a) Tebbe, F. N. Lewis Acidic Metal Alkyl-Transition Metal
Complex Interactions. I. Niobium and Tantalum Hydrides. J. Am.
Chem. Soc. 1973, 95, 5412−5414. (b) Fryzuk, M. D.; McConville, D.
H.; Rettig, S. J. Fragmentation-Recombination Reactions of the
(
8) Lohrey, T. D.; Maron, L.; Bergman, R. G.; Arnold, J.
Heterotetrametallic Re-Zn-Zn-Re Complex Generated by an Anionic
Rhenium(I) β-Diketiminate. J. Am. Chem. Soc. 2019, 141, 800−804.
(
i
i
9) Selected examples: (a) Schulz, S.; Schuchmann, D.; Westphal,
Electron-Rich Binuclear Hydride [(Pr
2
PCH
2
CH
2
CH
2
PPr
2
2
)Rh]
2
(μ-
2
i
i
U.; Bolte, M. Dizincocene as a Building Block for Novel Zn-Zn-
H) with Dibenzylzinc. X-ray Structure of [(Pr
2
2
PCH
2
CH
CH
PPr )-
2
Bonded Compounds? Organometallics 2009, 28, 1590−1592.
Rh] (μ-H) (μ-ZnCH Ph) . Organometallics 1990, 9, 1359−1360.
2
2
2
2
(
b) Schuchmann, D.; Westphal, U.; Schulz, S.; Flo
̈
rke, U.; Blas
̈
er,
(c) Fryzuk, M. D.; McConville, D. H.; Rettig, S. J. Reactions of the
i
i
D.; Boese, R. The Reaction of Dizincocene with Preservation of the
Electron-Rich Binuclear Hydride Complexes [{Pr P(CH ) PPr }-
2 2 x 2
G
DOI: 10.1021/acs.inorgchem.9b02062
Inorg. Chem. XXXX, XXX, XXX−XXX

Inorganic Chemistry
Article
Rh] (μ-H) (x = 2 or 3) with ZnR and MgR’ . Organometallics 1993,
White, A. J. P.; Crimmin, M. R. Room Temperature Catalytic Carbon-
Hydrogen Bond Alumination of Unactivated Arenes: Mechanism and
Selectivity. Chem. Sci. 2018, 9, 5435−5440.
(25) Xu, P.; Yao, Y.; Xu, X. Frustrated Lewis Pair-Like Reactivity of
Rare-Earth Metal Complexes: 1,4-Addition Reactions and Polymer-
izations of Conjugated Polar Alkenes. Chem. - Eur. J. 2017, 23, 1263−
1267.
(26) Vertesaljai, P.; Navaratne, P. V.; Grenning, A. J. Knoevenagel
Adducts as Trimethylenemethane Dipole Surrogates. Angew. Chem.,
Int. Ed. 2016, 55, 317−320.
2
2
2
2
1
2, 2152−2161. (d) Ohashi, M.; Matsubara, K.; Iizuka, T.; Suzuki, H.
Trinuclear Ruthenium Polyhydride Complexes with a Triply Bridging
Ligand: [{(η -C Me )Ru} -(μ -M)(μ-H) (μ -H)] (M = Li, MgiPr,
and ZnEt) and [{(η -C Me )Ru} (μ -M)(μ-H) ] (M = AlEt and
5
5
5
3
3
3
3
5
5
5
3
3
3
GaMe). Angew. Chem., Int. Ed. 2003, 42, 937−940. (e) Ohashi, M.;
Matsubara, K.; Suzuki, H. Ruthenium Polyhydrido Clusters Having a
5
Bridging Alkylzinc Group, [(η -C Me )Ru(μ-H)] (μ -ZnR) (μ -
5
5
3
3
n
3
5
H)2‑n and [(η -C Me )Ru] (μ-ZnR) (μ-H) (R = Me and Et; n =
5
5
2
n
4‑n
1
(
and 2). Organometallics 2007, 26, 2330−2339.
17) Kreider-Mueller, A.; Quinlivan, P. J.; Rauch, M.; Owen, J. S.;
But
Parkin, G. Synthesis, Structure and Reactivity of [Tm ]ZnH, a
Monomeric Terminal Zinc Hydride Compound in a Sulfur-Rich
Coordination Environment: Access to a Heterobimetallic Compound.
Chem. Commun. 2016, 52, 2358−2361.
(
18) Fafard, C. M.; Chen, C.-H.; Foxman, B. M.; Ozerov, O. V.
Covalent Palladium-Zinc Bonds and Their Reactivity. Chem. Commun.
007, 4465−4467.
19) (a) Buchwalter, P.; Rose,
2
(
́
J.; Braunstein, P. Multimetallic
Catalysis Based on Heterometallic Complexes and Clusters. Chem.
Rev. 2015, 115, 28−126. (b) Nesterov, D. S.; Nesterova, O. V.;
Pombeiro, A. J. L. Homo- and Heterometallic Polynuclear Transition
Metal Catalysts for Alkane C-H Bonds Oxidative Functionalization:
Recent Advances. Coord. Chem. Rev. 2018, 355, 199−222.
(
20) Bollermann, T.; Gemel, C.; Fischer, R. A. Organozinc Ligands
in Transition Metal Chemistry. Coord. Chem. Rev. 2012, 256, 537−
55.
21) Steinhoff, P.; Paul, M.; Schroers, J. P.; Tauchert, M. E. Highly
5
(
Efficient Palladium-Catalysed Carbon Dioxide Hydrosilylation
Employing PMP Ligands. Dalton Trans 2019, 48, 1017−1022.
(
22) (a) Marciniec, B. Hydrosilylation: A Comprehensive Review on
Recent Advances; Springer: Netherlands, 2009; pp 289−339
DOI: 10.1007/978-1-4020-8172-9. (b) Shirobokov, O. G.;
Kuzmina, L. G.; Nikonov, G. I. Nonhydride Mechanism of Metal-
Catalyzed Hydrosilylation. J. Am. Chem. Soc. 2011, 133, 6487−6489.
(
c) Postigo, L.; Royo, B. N-Heterocyclic Carbene Complexes of
Nickel as Efficient Catalysts for Hydrosilylation of Carbonyl
Derivatives. Adv. Synth. Catal. 2012, 354, 2613−2618. (d) Ghosh,
C.; Mukhopadhyay, T. K.; Flores, M.; Groy, T. L.; Trovitch, R. J. A
Pentacoordinate Mn(II) Precatalyst That Exhibits Notable Aldehyde
and Ketone Hydrosilylation Turnover Frequencies. Inorg. Chem.
2
015, 54, 10398−10406. (e) Zheng, T.; Li, J.; Zhang, S.; Xue, B.; Sun,
H.; Li, X.; Fuhr, O.; Fenske, D. Selective C-F and C-H Activation of
Fluoroarenes by Fe(PMe3)4 and Catalytic Performance of Iron
Hydride in Hydrosilylation of Carbonyl Compounds. Organometallics
2
(
016, 35, 3538−3545.
23) (a) Kim, Y.-J.; Lee, S.-C.; Park, J.-I.; Osakada, K.; Choi, J.-C.;
Yamamoto, T. Unsymmetrical and Symmetrical Dipalladium
Complexes with Bridging Diphenylsilyl Ligands. Structures of
(
Me P)Pd(μ-SiHPh ) Pd(PMe ) and [(Me P)Pd(μ-SiHPh )] in
3 2 2 3 2 3 2 2
the Solid State and in Solution. Organometallics 1998, 17, 4929−4931.
(
b) Kim, Y.-J.; Lee, S.-C.; Park, J.-I.; Osakada, K.; Choi, J.-C.;
Yamamoto, T. Dipalladium Complexes with Bridging Diorganosilyl
Ligands. Synthesis, Structure, and Properties of [LPd(μ-SiH(R)Ph)]2
(
R = Ph or Me; L = PMe , PEt or PMePh ). J. Chem. Soc., Dalton
3 3 2
Trans. 2000, 417−421. (c) Tanabe, M.; Yamada, T.; Osakada, K. Pd-
Pt Heterobimetallic and Pd-Pd or Pt-Pt Dinuclear Complexes with
Bridging Diphenylsilyl Ligands. Organometallics 2003, 22, 2190−
2
192. (d) Yamada, T.; Tanabe, M.; Osakada, K.; Kim, Y.-J. Palladium-
Platinum Heterobimetallic Complexes with Bridging Silicon Ligands.
Structure and Reaction with Isonitrile to Afford a Platinacyclopentane
Containing Si, N, and C Atoms. Organometallics 2004, 23, 4771−
4
777. (e) Tanabe, M.; Takahashi, A.; Yamada, T.; Osakada, K.
Dipalladium Complexes with Bridging Monoalkyl or Monophenyl
Silyl Ligands in the Solid State and in Solution. Organometallics 2013,
3
(
2, 1815−1820.
24) (a) Ekkert, O.; White, A. J. P.; Toms, H.; Crimmin, M. R.
Addition of Aluminium, Zinc and Magnesium Hydrides to Rhodium-
III). Chem. Sci. 2015, 6, 5617−5622. (b) Hooper, T. N.; Garcon, M.;
(
̧
H
DOI: 10.1021/acs.inorgchem.9b02062
Inorg. Chem. XXXX, XXX, XXX−XXX