Syntheses of transition metal methoxysiloxides

Article abstract of DOI:10.1039/c6dt04205h

The paper describes three methods for the preparation of methoxysiloxide complexes, a rare class of complexes of relevance to room temperature vulcanization (RTV) of polysiloxanes. The salt metathesis reaction involves the use of the recently described re

Full text of DOI:10.1039/c6dt04205h

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PAPER
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Efficient extraction of sulfate from water using
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DOI: 10.1039/C6DT04205H
Syntheses of Transition Metal Methoxysiloxides‡
Casseday P. Richers, Jeffery A. Bertke, and Thomas B. Rauchfuss*
School of Chemical Sciences, University of Illinois at UrbanaꢀChampaign
Urbana, IL 61801, USA
The paper describes three methods for the preparation of methoxysiloxide complexes, a rare
class of complexes of relevance to room temperature vulcanization (RTV) of polysiloxanes. The
salt metathesis reaction involves the use of the recently described reagent NaOSi(OMe)2Me
with various metal chlorides to give Cp*2Ti[OSi(OMe)2Me](OMe), (Me,MeN2N)NiOSi(OMe)2Me,
(IPr)CuOSi(OMe)2Me, and (triphos)CoOSi(OMe)2Me (Cp* = C5Me5, triphos = Me(CH2PPh2)3).
Several attempted reactions gave methoxide complexes instead, a pathway that is attributed to
the intermediacy of κ2ꢀOSi(OMe)2Me species. The diol Cp*2Zr(OH)2 reacts with excess
(MeO)3SiMe to give Cp*2Zr[OSi(OMe)2Me]2. In contrast the less nucleophilic Cp*2Ti(OH)2 was
unreactive. The third route to methoxysiloxide complexes involves the reaction of Cp*2M(O)(py)
with (MeO)3SiMe to give Cp*2M[OSi(OMe)2Me](OMe) in nearly quantitative yield (M = Ti, Zr).
The
structures
of
Cp*2Ti[OSi(OMe)2Me](OMe),
Cp*2Zr[OSi(OMe)2Me](OMe),
(IPr)CuOSi(OMe)2Me, and (triphos)CoOSi(OMe)2Me were confirmed by single crystal Xꢀray
diffraction.
Metal triorganosiloxides, compounds containing MꢀOꢀSiR3 linkages, are a wellꢀknown
class of complexes.1 In contrast, metal alkoxysiloxides, compounds containing MꢀOꢀ
Si(OR)nR’3ꢀn linkages, are less common, but perhaps more technologically relevant than
trioganosiloxides.2 These compounds, however, are limited almost exclusively to triꢀtertꢀ
butoxysiloxides.3
Transition metal methoxysiloxides are of interest as potential catalysts in the room
temperature vulcanization (RTV) of polysiloxanes. In RTV, silanolꢀterminated oligomers
are crosslinked upon treatment with methyltrimethoxysilane (MTM), resulting in
‡
Electronic supplementary information (ESI) available: Xꢀray crystallographic data for CCDC
1513680 formula C24H42O4Si1Ti1, CCDC1513681 formula C44H48Co1O3P3Si1, CCDC1513682 formula
C30H45Cu1N2O3Si1,0.5(C7H8),0.5(C4H10O1), CCDC1513683 formula C24H42O4Si1Zr1. For ESI and
crystallographic data in CIF or other electronic format see DOI:0000.

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materials employed in caulks and sealants (Scheme 1).4 Catalysts are required for this
process, most likely to facilitate hydrolysis of the MeOꢀSi functionalities. Typical
commercial catalysts are based on diorganotin(IV) carboxylates, but many metalꢀ and
nonmetalꢀbased catalysts have been identified.5 Little however has been published
about the mechanism of RTV.6 It is probable that methoxysiloxide complexes are
intermediates in metal/metalloidꢀcatalyzed RTV. Access to methoxysiloxides, however,
is not readily achieved from methoxy and ethoxysilanols, which are unstable in solution.
For example, methoxysilanols HOSi(OMe)2R (R = Me, Ph) condense even at low
temperatures to give disiloxanols HOSi(OMe)(R)OSi(OMe)2R.7 An alternative route to
methoxysiloxides presents itself with the recent availability of the salts, NaOSi(OMe)nR3ꢀ
n. These salts feature the conjugate base of the unstable methoxysilanols.
This paper evaluates three routes to metal complexes of nonbulky methoxylsiloxide
ligands NaOSi(OMe)3R (R = Ph and Me). Initial studies focused on salt metathesis
reactions using sodium methoxysiloxides NaOSi(OMe)nR3ꢀn.
This method is
complemented by the direct reaction of the methoxysilanes with hydroxyl and oxo
complexes. Two wellꢀdefined methoxysiloxide complexes were reported prior to this
work, (IPr)AuOSi(OMe)2Ph and (I/IPr)Ir(COD)[OSi(OMe)2Ph] (IPr = 1,3ꢀbis(2,6ꢀ
diisopropylphenyl)imidazolꢀ2ꢀylidene).8

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cat.
H2O
MeO Me
Si
Me2
Si
Me2
Si
Me2
Si
+
ꢀ MeOH
HO
O
O
OH
MeO
OMe
n
Me2
Si
Me2
Si
Me2
Si
O
O
O
O
Me
n
Me2
Si
Me2
Si
Me2
Si
Si
O
O
O
O
O
O
O
O
n
Si
Me2
Si
Si
Me2 n Me2
Scheme 1. Reactions involved in room temperature vulcanization (RTV) of silicone
polymers.
Results
SaltꢀMetathesis Routes to Methoxysiloxides.
The syntheses of group IV methoxysiloxides were initially pursued since
complexes of these metals have been identified as potential catalysts for RTV.9 More
specifically, the decamethylmetallocene derivatives of zirconium and titanium were
selected as the metal halides, since the metal centers in these complexes are relatively
resistant to redox reactions, have good NMR spectroscopic properties, and are
oxophilic.
Treatment of a THF solution of Cp*2ZrCl2 with one equivalent of NaOSi(OMe)2Me
produced the methoxy chloride complex, Cp*2Zr(OMe)Cl (1), in near quantitative yield
(eq 1). The reactions of Cp*2Zr(OMe)Cl and Cp*2ZrCl2 with one and two equivalents of
NaOSi(OMe)2Me, respectively, generated the dimethoxide Cp*2Zr(OMe)2 (2) (Scheme
2).10 No intermediates were observed in these reactions, and no reactions were
1
observed below 0 °C. Broad signals near δ 3.4 and 0 in the H NMR spectrum of the
crude reaction mixture suggest the formation of siloxane polymers, [OSi(OMe)Me]n.

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Scheme 2. The reactions of Cp*2ZrCl2 with 2 equivalents of NaOSi(OMe)2Me.
The addition of one equivalent of NaOSi(OMe)2Me to a THF solution of Cp*2TiCl2
initially produced Cp*2Ti[OSi(OMe)2Me](OMe) (3), together with unreacted dichloride.
Over the course of 24 h at room temperature, this reddish mixture degrades to a more
complex mixture. The addition of two equivalents of NaOSi(OMe)2Me to a THF solution
of Cp*2TiCl2, afforded solely the methoxy silanolate complex, 3 (eq 1). The latter
reaction proceeded in nearly quantitative yield over the course of 1 h at room
temperature. In the absence of Cp*2TiCl2, the product appeared to be indefinitely stable
as a THF solution at room temperature.
Cp*2TiCl2 + 2 NaOSi(OMe)2Me ꢀ Cp*2Ti[OSi(OMe)2Me](OMe)
(1)
3
The reactions of NaOSi(OMe)2Me with a range of late metal halides were also
examined. These reactions gave mixed results. Three new methoxysiloxide complexes
were prepared by the addition of NaOSi(OMe)2Me to solutions of the corresponding
metal
chlorides:
purple
(
Me,MeN2N)NiOSi(OMe)2Me
(
Me,MeN2N
=
bis(2ꢀ
dimethylaminophenyl)amide) (4), colorless (IPr)CuOSi(OMe)2Me (5), and yellowꢀgreen
(triphos)CoOSi(OMe)2Me (triphos = 1,1,1ꢀtris(diphenylphosphinomethyl)ethane) (6)
(Scheme 3). The structures of the Cu and Co products were verified by Xꢀray

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1
crystallography (Figure 1). The H NMR spectrum of the nickel complex 4 indicates a
diamagnetic complex, consistent with square planar geometry.
Crystallographic analysis of 5 reveals a linear geometry at copper, with a CꢀCuꢀO
angle of 179.37(12)° and C(1)ꢀCu(1) and Cu(1)ꢀO(1) bond distances of 1.848(3) and
1.798(2) Å, respectively. Silicon is disordered over two positions with SiꢀO(1) bond
distances of 1.588(2) and 1.607(6) Å. Both distances are shorter than the SiꢀOC bonds,
which are 1.636(4) and 1.639(4) Å, respectively. Disorder at silicon also resulted in the
measurement of two Cu(1)ꢀO(1)ꢀSi(1) angles: 126.72(14)° and 133.5(3)°.
In
comparison to the Cu(II) complex, Cu[OSi(OBut)3]2(py)2,11 the CuꢀOSi bond distance in
(IPr)Cu[OSi(OMe)2Me] is slightly shorter, the CuOꢀSi bond is slightly longer, and the Cuꢀ
OꢀSi bond angle is slightly smaller.
Crystallographic analysis of 6 reveals a distorted tetrahedral geometry around
cobalt. The PꢀCoꢀP angles range from 88.88(6) ꢀ 92.50(6)°. The overall geometry of
the CoOP3 coordination sphere deviates from 3ꢀfold symmetry with one OꢀCoꢀP angle
being significantly smaller (113.8(3)° or 110.1(3)°, depending on disorder, than the other
two OꢀCoꢀP angles, which range from 121.8(4) to 135.7(14). The CoꢀOSi and CoOꢀSi
bond distances of 1.878(8) and 1.572(9) Å observed in 5 are similar to those reported
for (PPh3)2CoOSiMe3 (1.857 and.1.602 Å).12 The CoꢀOꢀSi angle of 149.1(9)°, however,
is much smaller than the CoꢀOꢀSi angle of 180° found in (PPh3)2CoOSiMe3, reflecting
the more crowded nature of the latter.
The cobalt complex 6 gave a broad 1H NMR spectrum indicative of a paramagnetic
complex. Its magnetic moment indicates a lowꢀspin complex, like its precursor
(triphos)CoCl.

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LnMꢀCl + NaOSi(OMe)2Me
LnMꢀOSi(OMe)2Me
LnMꢀOSi(OMe)2Me
NMe2
=
PPh2
OMe
Cu O Si OMe
Me
OMe
N
N
OMe
Ph2
P
N Ni O Si OMe
Co O Si OMe
Me
Me
PPh2
NMe2
4
5
6
Scheme 3. Methoxysiloxide complexes prepared by salt metathesis.
Fig. 1 Crystal structures of 5 and 6 shown at the 50 % probability level. Hydrogen
atoms are omitted for clarity. Selected bond distances (Å) and angles (°): C1ꢀCu1,
1.848(3); Cu1ꢀO1, 1.798(2); C1ꢀCu1ꢀO1, 179.37(12); Cu1ꢀO1ꢀSi1, 126.72(14); Co1ꢀO1,
1.878(8); P1ꢀCo1ꢀSi1, 121.8(4); P2ꢀCo1ꢀSi1, 135.7(4), P3ꢀCo1ꢀSi1, 113.8(3); Co1ꢀO1ꢀ
Si1, 149.1(9).

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Several other metal halides reacted with NaOSi(OMe)2Me, but often complicated
mixtures were obtained. A few of these failed reactions, however, gave clean products.
Thus, CpRu(dppe)OTf gave the wellꢀknown hydride CpRu(dppe)H (7) in 65% yield
(Scheme 4).13
CpRu(dppe)OMe, which reacts to form the hydride.
This reaction is proposed to proceed via the intermediacy of
The latter reaction was
demonstrated by treating the chloro complex, CpRu(dppe)Cl, with NaOMe and in this
study by treating the triflate complex, CpRu(dppe)OTf, with NaOMe. The hydride was
identified by 1H NMR spectroscopy.
The reaction of [(Et,EtNacNac)Zn(ꢁꢀCl)]2 (Et,EtNacNac = 2ꢀ((2,6ꢀdiethylphenyl)amido)ꢀ
4ꢀ((2,6ꢀdiethylphenyl)imino)ꢀ2ꢀpentene) with NaOSi(OMe)2Me gave the known complex,
[(Et,EtNacNac)Zn(ꢁꢀOMe)]2 (8).14
NaOSi(OMe)2Me gave the methoxide cluster Fe4(acac)4(ꢁ2ꢀOMe)4(ꢁ3ꢀOMe)2Cl2 (9).15
Finally, the reaction of (acac)2FeCl and
Scheme 4. Proposed steps in the formation of CpRu(dppe)H from CpRu(dppe)OTf and
NaOSi(OMe)2Me. The conversion of CpRu(dppe)OMe to CpRu(dppe)H was
demonstrated independently.
Additions of Alkoxysilanes to Metal Hydroxides.

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Given the complicated nature of the reactions described above, attention turned to
routes involving metal hydroxides.
Me OMe
Si
OH
OH
+
Zr
C6D6
rt
MeO
OMe
Me OMe
Si
Me OMe
Si
Me OMe
Si
O
OMe
O
OMe
O
O
OMe
OMe
+
+
+ MeOH
Zr
Zr
Zr
OH
OMe
Si
Me OMe
10
11
12

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Fig. 2 1H NMR spectra collected at different time points for the reaction of Cp*2Zr(OH)2
with four equivalents of (MeO)3SiMe.
Cp*2Zr[OSi(OMe)2Me]2 over the course of 64 h.
The product mixture converges to
Precedent for the reaction of metal hydroxides with methoxysilanes is provided by
Nolan et al., who reported the additions of (MeO)3SiPh to (IPr)AuOH and
(IiPr)Ir(COD)OH to give (IPr)AuOSi(OMe)2Ph and (IiPr)Ir(COD)OSi(OMe)2Ph,
respectively.8a We showed that the addition of (MeO)3SiMe to (IPr)CuOH generated the
methoxysiloxide complex 5. We then tested the generality of this method, focusing on
the decamethylmetallocenes.
16
Treatment of a benzene solution of Cp*2Zr(OH)2
with one equivalent of
(MeO)3SiMe rapidly formed a mixture of three compounds. The 1H NMR chemical shifts
and integrated intensities are consistent with Cp*2Zr[OSi(OMe)2Me](OH) (10),
Cp*2Zr[OSi(OMe)2Me](OMe) (11), and Cp*2Zr[OSi(OMe)2Me]2 (12). The same three
compounds are generated using an excess (four equivalents) of (MeO)3SiMe, but in this
case, the mixture converges to Cp*2Zr[OSi(OMe)2Me]2 over the course of 64 h (Figure
2).
Qualitative tests show that other Cp*2Zr(IV)ꢀOH species are reactive towards
(MeO)3SiMe. For example, a benzene solution of Cp*2Zr(OH)(Cl) and one equivalent of
(MeO)3SiMe react over the course of several hours to give an approximately equimolar
mixture of Cp*2Zr[OSi(OMe)2Me](Cl) (13) and methoxy chloride 1. The formation of the
methoxy chloride complex is ascribed to the reaction of Cp*2Zr(OH)(Cl) with the
methanol produced from the intial condensation. In contrast to its rapid reaction with
Cp*2Zr(OH)2, (MeO)3SiMe was unreactive toward Cp*2Ti(OH)2 (24 h at 72 °C).

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The zinc hydroxide complex, [(Et,EtNacNac)Zn(ꢁꢀOH)]2,14 reacts with (MeO)3SiMe to
form the methoxide dimer, 8, in approximately 70% yield. The related cobalt complex
[Co(acac)2OH]2,15 failed to react with (MeO)3SiMe.
SiꢀO Activation by Zr=O and Ti=O Complexes.
Aside from the salt metathesis and metal hydroxide routes, a third route was
developed to methoxysiloxide complexes, the additions of methoxysilanes to metal oxo
complexes. Treatment of a C6D6 solution of Cp*2Zr(O)(py) with (MeO)3SiMe generated
the siloxyꢀmethoxy complex 11 in near quantitative yield (eq 2). The reaction was
1
complete within 1 h at 60 °C. The H NMR spectrum of 11 displays signals at δ 3.54
and 0.29 ppm for the SiOMe and SiMe groups, respectively.
Cp*2M(O)(py) + (MeO)3SiMe ꢀ Cp*2M[OSi(OMe)2Me](OMe) + py
(2)
2 (M = Ti)
11 (M = Zr)
The addition of (MeO)3SiMe to Cp*2Ti(O)(py) also led to the formation of the
1
methoxyꢀsiloxide complex 3. The yield is nearly quantitative. When monitored by H
NMR spectroscopy, the reaction was complete within an hour at 60 °C. In preparative
scale reactions, 3 was isolated as red pentaneꢀsoluble microcrystals.
The solid state structures of 11 and 3 are generally similar, featuring distorted
tetrahedral metal centers (Figure 3). The main difference in the structures is the metalꢀ
O bond lengths (Figure 4). The relative lengths of the MꢀOSi vs MꢀOC bonds are
reversed, which correlates with the MꢀOꢀSi angles. This trend is attributed to the
greater strength of Zr(IV) piꢀbonding to alkoxide

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Figure 3. Crystal structures of 11 and 3 shown at the 50 % probability level. Hydrogen
atoms are omitted for clarity. Selected bond distances (Å) and angles (°): Zr1ꢀO1,
2.0138(11); Zr1ꢀO4, 1.898(5); O1ꢀSi1, 1.5963(12); Si1ꢀO1ꢀZr1, 158.83(9); O1ꢀZr1ꢀO4,
95.74(9); C24ꢀO4ꢀZr1, 154.5(2); Ti1ꢀO1, 1.9214(14); Ti1ꢀO4, 1.974(2); Si1ꢀO1,
1.5909(1); Si1ꢀO1ꢀTi1, 163.75(10); O1ꢀTi1ꢀO4, 95.33(7); C24ꢀO4ꢀTi1, 130.43(17).
The ZrꢀOSi bond distance of 2.014 Ǻ in 11 is longer than the ZrꢀO bond distance of
1.964 Ǻ found in Cp2Zr(OSiPh3)Cl; the ZrOꢀSi bond distance of 1.596 is shorter (vs.
1.623 Ǻ in Cp2Zr(OSiPh3)Cl), and the ZrꢀOꢀSi bond angle of 159° is more acute (vs.
174° in Cp2Zr(OSiPh3)Cl).17 Similarly, the TiꢀOSi bond in 3 (1.921 Ǻ) is longer than the
TiꢀOSi bond in Cp2Ti(OSiPh3)Cl (1.842 Ǻ), and the TiOꢀSi bond (1.591 Ǻ in 3 is shorter
(1.615 Ǻ in Cp2Ti(OSiPh3)Cl). The TiꢀOꢀSi bond angles in 3 and in Cp2Ti(OSiPh3)Cl are
approximately the same (~164°).
Treatment of a THF solution of Cp*2Zr[OSi(OMe)2Me](OMe) with NaOSi(OMe)2Me
1
did not affect the H NMR signals of the zirconium complex, but did consume the
sodium siloxide.
Reactivity of Transition Metal Methoxysiloxides Towards Water

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The hydrolysis of the methoxysiloxide complexes was briefly surveyed. No reaction
was observed between the copper(I) complex 5 and water. Otherwise all other
complexes reacted with even equimolar amounts of water. The addition of one
equivalent of water to solutions of 2 and 11 resulted in hydrolysis of the metal
methoxide bond. It is of interest to investigate these reactions further, especially those
reactions that leave the MOSi bond intact.
Discussion
The efforts described above focused on the syntheses of complexes containing
methoxysiloxide ligands. Three different methods were developed. The first method,
salt metathesis, was the easiest to employ, but gave unpredictable results, often leading
to the methoxide complexes. The addition of NaOSi(OMe)2Me to a solution of
Cp*2ZrCl2, for example, gave Cp*2Zr(OMe)Cl, under conditions in which the expected
product, Cp*2Zr[OSi(OMe)2Me]Cl, is stable. Likewise the addition of NaOSi(OMe)2Me
to a solution of Cp*2Zr(OMe)Cl gave Cp*2Zr(OMe)2, despite the stability of
Cp*2Zr[OSi(OMe)2Me](OMe).
The absence of observed intermediates in these
reactions, and the fact that NaOSi(OMe)2Me does not react with
Cp*2Zr[OSi(OMe)2Me](OMe) to give Cp*2Zr(OMe)2 demonstrates that NaOSi(OMe)2Me
can function as a source of methoxide. This reactivity was recently exploited for the
synthesis of methyl aryl ethers from aryl bromides, (MeO)3Si(C2H3), and NaOH.18 The
existence of a simple methoxideꢀmethoxysiloxide equilibrium in the reactions of sodium
methoxysiloxides is not indicated: the treatment of NaOSi(OMe)2Me with Et3SiCl gave
primarily Et3SiOSi(OMe)2Me.
Only trace amounts of Et3SiOMe and

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Et3SiOSi(OMe)MeOSi(OMe)2Me were observed. In contrast to the Cp*2Zr(IV) chemistry,
Cp*2Ti[OSi(OMe)2Me](OMe) cleanly forms from the addition of NaOSi(OMe)2Me to
Cp*2Ti(OMe)Cl product distribution is proposed to be related to the relative lability of the
TiꢀCl vs ZrꢀCl bonds. For later transition metals, the methoxysiloxide complexes are
stabilized by crowded metal sites of low Lewis acidity. Otherwise, methoxide
complexes appear to form. Methoxides are proposed to arise via the intermediacy of
κ2ꢀmethoxysiloxide complexes, analogues of which are wellꢀknown for the OSi(OBuꢀt)3
ligand.3,19
In comparison to salt metathesis routes, the additions of methoxysilanes to metal
hydroxides involves gentler conditions. This method, however, was not without its
limitations.
The addition of (MeO)3SiMe to Cp*2Ti(OH)2 failed to produce a
methoxysiloxide. The nonꢀreactivity of Cp*2Ti(OH)2, when compared to Cp*2Zr(OH)2
and (IPr)CuOH, is attributed to the diminished nucleophilicity of the titanium hydroxide.
The diverse nucleophilicity of metal hydroxide complexes is well known.20
The third method for the synthesis of methoxysiloxides, the additions SiꢀOMe bonds
across M=O bonds, is new. Related reactions, however, have been reported or
proposed. Schmidbaur showed that Re2O7 reacts with hexamethyldisiloxane to give
O3ReOSiMe3,21 and Nesmeyanov proposed that "(PrnO)2TiO" reacts with (PrnO)2SiMe2
to form (PrnO)3TiOSi(OPrn)Me2 and [(PrnO)3TiO]2SiMe2.1c,22 In addition, Breweries and
coꢀworkers hypothesized that a titanocene oxide complex reacts with a vinylsilane to
form a titanocene vinyl siloxide complex addition of a CꢀSi bond across a Ti=O bond.23
Our studies focused on the additions of SiꢀOMe bonds across the M=O bonds of the

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zirconium and titanium oxo complexes, Cp*2ZrO(py) and Cp*2TiO(py).
complexes feature nucleophilic oxides that participate in cycloadditions.24
These
Conclusions
Methoxysiloxide complexes can be prepared by a variety of methods allowing
access to complexes of diverse transition metals. At this early stage, the chief limitation
in the scope of such compounds is the apparent incompatibility of methoxysiloxides with
highly Lewis acidic metal centers. The ligandꢀcentered reactivity of the methoxysiloxide
complexes is an area of potential interest.
Experimental Section
Materials and Methods
Unless otherwise indicated, all reactions were conducted in a nitrogenꢀfilled glovebox or
under an argon or N2 atmosphere using standard Schlenk techniques. (IPr)CuCl,25
(IPr)CuOH,26 and (Me,MeN2N)NiCl,27 were synthesized according to literature procedures.
The following compounds were prepared by literature methods or as detailed in the SI:
Cp*2Ti(C2H4),28
Cp*2Ti(O)(py),29
Cp*2Zr(OH)Cl,16
Cp*2Zr(OH)(OTf),30
and
(triphos)CoCl31. Sodium hydroxide (Fisher), (MeO)3SiMe (Aldrich), (MeO)3SiPh (Gelest),
Cp*2TiCl2 (Gelest), and Cp*2ZrCl2 (Gelest) were used without further purification.
13
Solvents were dried and degassed on an MBraun MBꢀSPS solvent system. 1H, C,
and 31P NMR spectra were recorded on Varian UNITY 500 instruments. 29Si NMR
1
13
spectra were recorded on a Varian UNITY 600 instrument. H and C chemical shifts

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are reported relative to the peak of residual solvent. 31P NMR chemical shifts are
referenced to 85% phosphoric acid. 29Si NMR chemical shifts are referenced to SiMe4.
Elemental analyses were conducted in the School of Chemical Sciences Microanalysis
Laboratory utilizing a Model CE 440 CHN Analyzer.
Cp*2Ti[OSi(OMe)2Me](OMe) (3)
To a solution of Cp*2Ti(O)(py) (116 mg, 2.81 x 10ꢀ4 mol, 1 equivalent) in THF (10 mL)
was added (MeO)3SiMe (41 ꢁL, 39 mg, 2.9 x 10ꢀ4 mol, 1 equivalent). The reaction was
stirred at room temperature for 24 h. The color of the solution slowly changed from
orange to red. The volatiles were removed under vacuum to leave a red solid. Yield:
1
124 mg (2.64 x 10ꢀ4 mol, 94 %). H NMR (C6D6): δ 4.20 (s, 3H), 3.54 (s, 6H), 1.92 (s,
13
29
30H), 0.34 (s, 3H). C{1H}( NMR (C6D6): δ 123.81, 65.71, 49.72, 12.06, ꢀ3.24. Si{1H}
NMR (C6D6): δ 46.20. Anal. Calcd for C24H42O4SiTi (470.55): C, 61.26; H, 9.00. Found:
C, 61.00; H, 8.94. Single crystals were obtained from cold pentane.
Cp*2Zr[OSi(OMe)2Me](OMe) (11)
To a solution of Cp*2Zr(OH)Cl (400 mg, 9.65 x 10ꢀ4 mol, 1 equivalent) in THF (5 mL)
was added potassium hexamethyldisilylazide (KHMDS, 193 mg, 9.65 x 10ꢀ4 mol, 1
equivalent), followed by (MeO)3SiMe (138 ꢁL, 131 mg, 9.65 x 10ꢀ4 mol, 1 equivalent).
The mixture was stirred at room temperature for 24 h. A cloudy, yellow solution
developed. The solvent was removed under vacuum, and the residual solid was
extracted into toluene (3 mL). The toluene solution was filtered through Celite, rinsing
with additional toluene (2 x 3 mL). The combined filtrates were evaporated, yielding a
pale yellow solid. Crystals were grown by slow evaporation of solvent from a pentane
1
solution at ꢀ40 °C. Yield: 444 mg (8.64 x 10ꢀ4 mol, 89 %). H NMR (C6D6): δ 3.93 (s,

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3H), 3.54 (s, 6H), 1.94 (s, 30H), 0.29 (s, 3H). 13C{1H} NMR (C6D6): δ 120.30, 58.23,
49.90, 11.65, ꢀ4.01. Anal. Calcd for C24H42O4SiZr (513.91): C, 56.09; H, 8.24. Found:
C, 55.93; H, 7.95.
(
Me,MeN2N)NiOSi(OMe)2Me (4)
To a solution of (Me,MeN2N)NiCl (400 mg, 1.14 x 10ꢀ3 mol, 1 equivalent) in THF (5 mL)
was added a solution of NaOSi(OMe)2Me (165 mg, 1.14 x 10ꢀ3 mol, 1 equivalent) in THF
(2 mL). The reaction was stirred at room temperature for 24 h. A color change from
brown to dark purple was observed. The THF solvent was removed under vacuum, and
the residual solid extracted into toluene (20 mL). The toluene solution was filtered
through Celite on a glass frit. Toluene was removed under vacuum leaving a purple
solid. The solid was washed with pentane (20 mL) and dried under vacuum. Yield: 434
1
mg, 9.97 x 10ꢀ4 mol, 87 %. H NMR (499 MHz, C6D6): δ 7.38 (dd, 2H, J = 8.4, 1.3 Hz),
6.92 (ddd, 2H, J = 8.4, 7.2, 1.4 Hz), 6.55 (dd, 2H, J = 8.1, 1.3 Hz), 6.36 (ddd, 2H, J = 8.1,
7.2, 1.3 Hz), 3.59 (s, 6H), 2.57 (s, 12H), 0.23 (s, 3H). 13C{1H} NMR (C6D6): δ 148.41,
147.54, 128.66, 120.73, 116.03, 115.00, 50.23, 50.11, ꢀ4.04.
Anal. Calcd for
C19H29N3NiO3Si (434.24): C, 52.55; H, 6.73; N, 9.68. Found: C, 52.71; H, 6.74; N, 9.42.
(IPr)CuOSi(OMe)2Me (5)
Method A. To a solution of (IPr)CuOH (206 mg, 4.4 x 10ꢀ4 mol, 1 equivalent) in toluene
(5 mL) was added (MeO)3SiMe (63 ꢁL, 60 mg, 4.4 x 10ꢀ4 mol, 1 equivalent). The
reaction was stirred at room temperature for 1 h before all volatiles were removed under
vacuum. The residual solid was washed with pentane, then dried under vacuum. A
white solid (196 mg, 3.4 x 10ꢀ4 mol) was obtained. Yield: 78 %. The NMR data matched
those for the complex obtained by method B. Method B. To a solution of (IPr)CuCl (100

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mg, 2.1 x 10ꢀ4 mol, 1 equivalent) in THF (1 mL) was added NaOSi(MeO)2Me (30 mg, 2.1
x 10ꢀ4 mol, 1 equivalent). The reaction mixture was stirred at room temperature for 1 h
before all volatiles were removed under vacuum. The solid residue was then extracted
into toluene, and this extract was filtered through Celite to remove any NaCl. The
filtrate was collected, and the toluene was removed under vacuum leaving a white solid.
1
Yield: 109 mg, 1.90 x 10ꢀ4 mol, 92 %. H NMR (THFꢀd8): δ 7.47 (s, 2H) 7.47 (t, 2H, J =
7.8 Hz), 7.35 (overlapping signals, 3H), 2.94 (s, 6H), 2.65 (heptet, 4H, J = 6.9 Hz), 1.33
(d, 12H, J = 6.9 Hz), 1.23 (d, 12H, J = 6.9 Hz), ꢀ0.57 (s, 3H). 13C{1H} NMR (THFꢀd8): δ
182.63, 146.59, 136.28, 130.89, 124.76, 49.10, 29.57, 25.00, 24.09, 4.57. Anal. Calcd
for C30H45CuN2O3Si (573.33): C, 62.85; H, 7.91; N, 4.89. Found: C, 62.73; H, 7.84; N,
5.16. Crystals were obtained upon cooling a pentane solution to ꢀ40 °C.
(triphos)CoOSi(OMe)2Me (6)
To a solution of (triphos)CoCl (400 mg, 5.56 x 10ꢀ4 mol, 1 equivalent) in THF (3 mL) was
added a solution of NaOSi(OMe) (80.2 mg, 5.56 x 10ꢀ4 mol, 1 equivalent) in THF (3 mL).
The resulting heterogeneous solution was stirred rapidly at room temperature for 1 h or
until it was completely homogeneous. Solvent was then removed from the dark green
solution leaving a green precipitate. The precipitate was extracted into dry CH2Cl2, and
this extract was filtered through Celite. The filtrate was collected, and the CH2Cl2 was
removed under vacuum leaving a green solid (423 mg, 5.26 x 10ꢀ4 mol, 94 % yield).
Crystals suitable for Xꢀray diffraction were grown from concentrated solutions of
(triphos)CoOSi(OMe)2Me in pentane.
Reaction of [(Et,EtNacNac)Zn(ꢁꢀOH)]2 with (MeO)3SiMe

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To a solution of [(Et,EtNacNac)Zn(ꢁꢀOH)]2 (10 mg, 1.13 x 10ꢀ5 mol, 1 equivalent) in C6D6
(0.5 mL) was added (MeO)3SiMe (3.2 µL, 3.1 mg, 2.26 x 10ꢀ5 mol, 2 equivalent) at
1
room temperature. The solution was transferred to an NMR tube, and an H NMR
1
spectrum was collected within 10 min. of mixing. The H NMR spectrum revealed
signals at δ 3.44 (s), 2.44 (m), 1.54 (s), and 0.17 (s) in a 6:4:6:3 ratio, consistent with
the
SiꢀOMe,
ArCH2CH3,
ArN=CCH3,
and
SiꢀMe
resonances
of
a
(
Et,EtNacNac)ZnOSi(OMe)2Me complex. In addition to these signals, a signal at δ 3.29
reveals the formation of MeOH, and signals at δ 3.54 (broad) and 1.42 indicate the
formation of [(Et,EtNacNac)Zn(µꢀOMe)]2.
Acknowledgements
This research was supported by NSF CHE 15ꢀ66023. Dow Corning Corporation
sponsored initial stages of this project. We thank Drs. Loren Durfee, Shuanbing Han,
and Matthew Olsen for advice.
Notes and references

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Table of contents graphic
NaOSi(OMe)2Me
Me
X
M
M
M
OMe
OMe
Si
Si(OMe)3Me
Si(OMe)3Me
OH
O
LnM
O