[2+2] cycloaddition products of zirconium and hafnium hydrazinediides with allenes and heteroallenes and their thermally induced rearrangements

Article abstract of DOI:10.1021/om300143h

Reactions of the hydrazinediido complexes [M(N₂ ^TBSN_py)(NNPh₂)(py)] (M = Zr (1a), Hf (1b)) with (hetero)allenes result in a variety of [2 + 2] cycloaddition products of the general type [M(N₂^TBSN_py)(κ²N, E-(E(E′R)NNPh₂)(py)] (E = CH₂, S; E′ = CH, N; R = alkyl, aryl). The reaction of [Zr(N₂^TBSN _py)(NNPh₂)(py)] (1a) with 1 molar equiv of phenyl or mesityl isothiocyanate at room temperature yields [Zr(N₂ ^TBSN_py)(κ²N,S-SC(NAr)NNPh ₂)(py)] (Ar = phenyl (2a), mesityl (2b)). Reacting the hydrazinediides [M(N₂^TBSN_py)(NNPh ₂)(py)] (M = Zr (1a), Hf (1b)) with allenes results in the formation of the metallaazacyclobutanes [M(N₂^TBSN _py)(κ²N,C-N(NPh₂)CH₂CCH(R)) (py)] (M = Zr, R = Ph (4a), cyclohexyl (5a), methyl (6); M = Hf, R = phenyl (4b), cyclohexyl (5b)). Subsequent heating of the cycloaddition products revealed different reactivity patterns: the complex [Zr(N₂ ^TBSN_py)(κ²N,S-SC(NAr)NNPh ₂)(py)] (2a) forms the isomerization product [Zr(N₂ ^TBSN_py)(κ²N,S-SC(NNPh₂))NPh] (3), retaining the N-N bond of the hydrazide. In contrast, the metallacyclobutanes 4a,b and 5a,b show a tendency toward N-N bond cleavage, resulting in the formation of the C-N- and C-C-coupled product complexes [M(κ⁴N,N,N,N-N₂^TBSN_pyNC(Me) CHCy)(NPh₂)] (M = Zr (7a), Hf (7b)), [Zr(N₂ ^TBSN_py)(κ²N,C-(Ph)NC₆H ₄C(Me)C(Ph)NH)] (8) and [Zr(κ⁴N,N,N,N-N ₂^TBSN_pyNC(Me)=CHPh)(NPh₂)] (9).

Full text of DOI:10.1021/om300143h

Article
pubs.acs.org/Organometallics
[2 + 2] Cycloaddition Products of Zirconium and Hafnium
Hydrazinediides with Allenes and Heteroallenes and Their Thermally
Induced Rearrangements
Thorsten Gehrmann, Gudrun T. Plundrich, Hubert Wadepohl, and Lutz H. Gade*
Anorganisch-Chemisches Institut, Universitat Heidelberg, Im Neuenheimer Feld 270, 69120 Heidelberg, Germany
̈
S
* Supporting Information
TBS
ABSTRACT: Reactions of the hydrazinediido complexes [M(N2 Npy)-
(NNPh2)(py)] (M = Zr (1a), Hf (1b)) with (hetero)allenes result in a
variety of [2 + 2] cycloaddition products of the general type
TBS
[M(N2 Npy)(κ2N,E-(E(E′R)NNPh2)(py)] (E = CH2, S; E′ = CH,
TBS
N; R = alkyl, aryl). The reaction of [Zr(N2 Npy)(NNPh2)(py)] (1a)
with 1 molar equiv of phenyl or mesityl isothiocyanate at room
temperature yields [Zr(N2 Npy)(κ2N,S-SC(NAr)NNPh2)(py)] (Ar =
TBS
TBS
phenyl (2a), mesityl (2b)). Reacting the hydrazinediides [M(N2 Npy)-
(NNPh2)(py)] (M = Zr (1a), Hf (1b)) with allenes results in the
TBS
formation of the metallaazacyclobutanes [M(N2 Npy)(κ2N,C-N(NPh2)-
CH2CCH(R))(py)] (M = Zr, R = Ph (4a), cyclohexyl (5a), methyl (6);
M = Hf, R = phenyl (4b), cyclohexyl (5b)). Subsequent heating of the
cycloaddition products revealed different reactivity patterns: the complex
[Zr(N2 Npy)(κ2N,S-SC(NAr)NNPh2)(py)] (2a) forms the isomerization product [Zr(N2 Npy)(κ2N,S-SC(NNPh2))-
NPh] (3), retaining the N−N bond of the hydrazide. In contrast, the metallacyclobutanes 4a,b and 5a,b show a tendency toward
N−N bond cleavage, resulting in the formation of the C−N- and C−C-coupled product complexes [M(κ4N,N,N,N-
TBS
TBS
TBS
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N2 NpyNC(Me)CHCy)(NPh2)] (M = Zr (7a), Hf (7b)), [Zr(N2 Npy)(κ2N,C-(Ph)NC6H4C(Me)C(Ph)NH)] (8) and
[Zr(κ4N,N,N,N-N2 NpyNC(Me)=CHPh)(NPh2)] (9).
TBS
of zirconium and hafnium hydrazinediido complexes with
several allenes and heteroallenes, as well as some pathways of
their thermal rearrangement and fragmentation.
INTRODUCTION
■
Azametallacycles of the group 4 elements are key intermediates
in a range of stoichiometric and catalytic C−N and C−C
coupling reactions mediated by these metals.1,2 The most
intensely studied catalytic transformation involving such species
is the hydroamination of alkynes.3−8
RESULTS AND DISCUSSION
■
Synthesis and Structural Characterization of [2 + 2]
Cycloadducts of a Zirconium Hydrazinediido Complex
with Isothiocyanates and Their Thermal Rearrange-
ment. Reaction of the hydrazinediido zirconium complex
In contrast, after early pioneering work from Bergman’s
group,9 [2 + 2] cycloadditions of group 4 metal hydrazinediido
complexes have only been looked into systematically in recent
years.10 The reactions of titanium and zirconium hydrazinedii-
do complexes with alkynes which lead to hydrohydrazination11
or N−N bond cleavage products12 have been studied and
modeled in detail, whereas much less is known about the
reactivity toward allenes. In general, reactions of hydrazinediido
titanium complexes with allenes or heteroallenes give stable [2
+ 2] cycloaddition products, they may lead to double substrate
insertion into the Ti−hydrazido double bond, or tend to
undergo metathesis to give N-aminoisothiocyanates.10b,c
However, all these reactions occur with retention of the
hydrazido N−N double bond. In contrast, a zirconium
hydrazinediido/phenyl allene adduct was found to react
under N−N bond scission upon heating.12d With this pattern
of reactivity in mind and given the lack of investigations
focusing on the heavier group 4 metal hydrazinediido reactivity,
we began systematic studies in this field.13 Here we report the
isolation and characterization of [2 + 2] cycloaddition products
[Zr(N2 Npy)(NNPh2)(py)] (1a; [N2 Npy]2− = [C5H4NC-
(CH3)(CH2NSitBuMe2)2]2−) with 1 molar equiv of phenyl or
mesityl isothiocyanate yielded the [2 + 2] cycloaddition
TBS
TBS
TBS
products [Zr(N2 Npy)(κ2N,S-SC(NPh)NNPh2)(py)]
(2a) and [Zr(N2 Npy)(κ2N,S-SC(NMes)NNPh2)(py)]
TBS
(2b), respectively (Scheme 1).
Addition of isothiocyanates to titanium hydrazinediides has
been described in the literature,10 whereas these reactions are
unprecedented for zirconium. Cycloaddition products 2a,b are
both formed selectively and are stable at room temperature.
Their 1H and 13C NMR spectra are consistent with the
formation of complexes with Cs symmetry. Furthermore, it is
evident that both complexes contain one pyridine donor ligand
Received: February 22, 2012
Published: April 3, 2012
© 2012 American Chemical Society
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Scheme 1. Reaction of the Hydrazinediido Zirconium
Complex 1a with Isothiocyanates To Give [2 + 2]
Cycloaddition Products
Table 1. Selected Bond Lengths (Å) and Angles (deg) for
Complexes 2a,b
2a
2b
Zr−N(1)
Zr−N(3)
Zr−N(4)
Zr−S
C(22)−S
C(22)−N(4)
C(22)−N(6)
N(4)−N(5)
2.076(4)
2.386(4)
2.218(4)
2.544(1)
1.773(5)
1.374(7)
1.289(6)
1.428(5)
2.0740(13)
2.3777(13)
2.2039(15)
2.5680(8)
1.779(1)
1.376(2)
1.277(2)
1.415(2)
Zr−N(4)−C(22)
Zr−S−C(22)
107.0(3)
83.4(2)
107.64(8)
82.63(6)
N(4)−C(22)−N(6)
N(4)−C(22)−S
N(6)−C(22)−S
126.2(5)
106.0(3)
127.8(4)
126.3(1)
106.10(9)
127.62(11)
mean plane 0.01 Å for both complexes). The planar
environment of C(22) (∑∠C22 = 360.0°) and the exocyclic
C(22)−N(6) distance (1.289(6) Å (2a) and 1.277(2) Å (2b))
are consistent with a C−N double bond.14
coordinated to the metal center. The 15N NMR shifts in the
metallacycle are in good accordance with those observed for the
related compound [Cp*Ti(NxylN)(κ2N,S-SC(NPh)-
NNPh2)]11g (2a, δ 129.8 (NPh2), 209.5 (Zr-N), 244.6 (CN-
Ph); [Cp*Ti(NxylN)(κ2N,S-SC(NPh)NNPh2)], δ 126.9
(NPh2), 266.2 (Ti-N), 245.1 (CN-Ph)).
When 2b is heated, nonselective degradation is observed,
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whereas for 2a the single isomerization product [Zr(N2 Npy)-
(κ2N,S-SC(NNPh2)NPh)] (3) is detected (Scheme 1). The
analytical data as well as the 1H, 13C, and 15N NMR
spectroscopic data are consistent with the depicted structure.
The neutral pyridine ligand is no longer coordinated, and the
signal sets for the remaining groups are similar to those
observed for complexes 2a,b. The N−N bond of the hydrazide
has remained intact, as is indicated by the marginal shift of the
15Nβ NMR signals (2a, δ 129.8; 3, δ 129.9). The occurrence of
a κ2N,N′-coordinated ligand as found in titanium10c,11g and
scandium15 complexes can be excluded, since the 13C NMR
signal of C22 is only slightly shifted downfield (δ 159.4 in 2a, δ
168.1 in 3). In contrast, for a κ2N,N′-coordinated form the 13C
NMR resonance of a hypothetical CS unit would be
expected around 200 ppm (δ 198.1 in [Cp*Ti(NxylN)-
(κ2N,N′-PhNC(S)NNPh2)]).11g The 15N NMR resonance
of the N4 atom in complex 3 is also consistent with the
formation of an exocyclic CNNPh2 moiety: the observed
shift of δ 271.2 lies in the typical range for hydrazones.16 Such
On the basis of these similarities the structure with κ2N,S
ligation as shown in Scheme 1 was suggested and subsequently
confirmed by single-crystal X-ray structure analyses of
complexes 2a,b. The molecular structures of both complexes
are shown in Figure 1; selected bond lengths and angles are
given in Table 1.
The molecular geometry in complexes 2a,b cannot be readily
described by reference to classic coordination polyhedra. The
structures are related to those found for [2 + 2] cycloaddition
products of complex 1a with other unsaturated substrates.10d
The Nα atom of the former hydrazinediido ligand is coupled to
the isothiocyanate carbon atom and lies beneath a virtual plane
defined by N1, N2, and the metal atom. The four-membered
metallacycles are essentially planar (rms deviation from the
Figure 1. Molecular structures of the [2 + 2] cycloaddition products 2a (left) and 2b (right). H atoms are omitted for clarity.
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an isomer can be regarded as an intermediate in the formation
of a zirconium sulfido complex upon release of N-amino-
carbodiimide, as reported recently by Mountford et al.10c
Synthesis and Structural Characterization of [2 + 2]
Cycloadducts with Allenes. Reactions of hydrazinediido
TBS
complexes [M(N2 Npy)(NNPh2)(py)] (M = Zr (1a), Hf
(1b)) with phenyl allene, cyclohexyl allene, and methyl allene
TBS
yields the metallaazacyclobutanes [Zr(N2 TBSNpy)(κ2N,C-N-
(NPh2)CH2CCH(Ph))(py)] (4a), [Zr(N2 Npy)(κ2N,C-N-
TBS
(NPh2)CH2CCH(Cy))(py)] (5a), and [Zr(N2 Npy)-
(κ2N,C-N(NPh2)CH2CCH(Me))(py)] (6) by [2 + 2]
cycloaddition reactions with Markovnikov regioselectivity. For
the hafnium complex 1b only the phenyl derivative [Hf-
TBS
(N2 Npy)(κ2N,C-N(NPh2)CH2CCH(Ph))(py)] (4b) and
cyclohexyl derivative [Zr(N2 Npy)(κ2N,C-N(NPh2)CH2C
TBS
CH(Cy))(py)] (5b) were isolated (Scheme 2).
Figure 2. Molecular structure of the [2 + 2] cycloaddition product 4a.
H atoms are omitted for clarity. Selected bond lengths (Å) and angles
(deg): Zr−N(4) = 2.183(1), Zr−C(22) = 2.334(1), N(4)−N(5) =
1.415(2), C(22)−C(23) = 1.495(2), C(23)−N(4) = 1.395(2),
C(23)−C(24) = 1.361(2); Zr−C(22)−C(23) = 91.91(8), Zr−
N(4)−N(5) = 139.55(8), C(24)−C(23)−N(4) = 124.5(1), N3(1)−
Zr−N(6) = 140.93(4).
Scheme 2. Formal [2 + 2] Cycloadditions of Complexes 1a,b
with Allenes Yielding the Metallacycles 4a,b, 5a,b, and 6
All five complexes were isolated and characterized
spectroscopically and analytically. Single-crystal X-ray structure
analyses established the regioselectivity of the cycloaddition
product for the zirconium phenyl derivative 4a and the hafnium
cyclohexyl compound 5b. Their molecular structures, which are
depicted in Figures 2 and 3, respectively, are related to those of
the isothiocyanate cycloaddition products 2a,b. Here again, the
usual deltahedral coordination geometries for 6-fold coordina-
tion do not apply, and the molecular geometries are best
described as being derived from a triangulated dodecahedron
(coordination number 8) with two of its vertices removed.
Thermally Induced N−N Bond Cleavage and Rear-
rangement Reactions. Heating the [2 + 2] cycloaddition
product 5a at 80 °C in toluene led to its conversion to one
Figure 3. Molecular structure of the [2 + 2] cycloaddition product 5b.
H atoms are omitted for clarity. Selected bond lengths (Å) and angles
(deg): Hf−N(4) = 2.160(2), Hf−C(22) = 2.290(2), N(4)−N(5) =
1.420(3), C(22)−C(23) = 1.507(3), C(23)−N(4) = 1.406(3),
C(23)−C(24) = 1.346(3); Hf−C(22)−C(23) = 92.9(1), Hf−
N(4)−N(5) = 141.0(1), C(24)−C(23)−N(4) = 128.4(2), N(3)−
Hf−N(6) = 141.78(7).
TBS
main reaction product, [Zr(κ4-N,N,N,N-N2 NpyNC(Me)
CHCy)(NPh2)] (7a; 95% yield) (Scheme 3).
Likewise, heating the hafnium compound 5b also gave the
corresponding rearrangement product [Hf(κ4-N,N,N,N-
Scheme 3. Thermolysis of the [2 + 2] Cycloaddition
Products 5a,b
TBS
N2 NpyNC(Me)CHCy)(NPh2)] (7b), albeit in lower
yield (50%). The analytical and spectroscopic data of 7a,b
indicate the absence of mirror symmetry for both species. A
1
detailed H and 15N NMR HMBC NMR study led to the
structural assignment of the C−H activation products, as shown
in Figure 4 for 7b.
Correlation of the protons of a newly formed methylene
group with both the 15N(4) and 15N(2) nuclei as observed in
1
the H 15N HMBC NMR spectrum provided direct evidence
for the insertion of the Nα atom (N4) into one of the methyl
C−H bonds of the tert-butyldimethylsilyl substituents on the
tripodal diamido-pyridyl ligand. The resonance of the 15Nβ
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Figure 4. 15N−1H correlated NMR spectrum of complex 7b.
nucleus (N5Ph2) (δN(5) 192.7 ppm) is shifted downfield
compared to those of the corresponding complex 5b
(δN(5)(5b) 123.1 ppm), which is consistent with the cleavage
of the Nα−Nβ bond and coordination of the N5Ph2 fragment on
the central atom, as also found in previous studies.13
Given the lack of selectivity in the transformations of
complexes 4a and 5a,b to the metallacyclic species represented
in Schemes 3 and 4, a systematic investigation of the underlying
mechanism was not possible. However, in view of the related
transformations of the zirconium hydrazinediides with alkynes,
which we studied in detail previously,12d,e we propose the
reaction sequences depicted in Scheme 5. The intramolecular
attack and coupling of the N−silyl unit, as observed in
complexes 7a,b and 9 (represented in Scheme 5 as III) is
Finally, thermolysis of complex 4a also yields two products,
TBS
namely [Zr(N2 Npy)(κ2N,C-(Ph)NC6H4C(Me)C(Ph)-
TBS
NH)}] (8) and [Zr(κ4-N,N,N,N-N2 NpyNC(Me)CHPh)-
(NPh2)] (9) (Scheme 4). The formation of the diazazircona-
Scheme 4. Thermolysis of the Metallacyclic Complex 4a
Scheme 5. Proposed Mechanistic Scheme for the Thermal
Transformation of the [2 + 2] Hydrazinediide/Allene
Cycloaddition Products (I) to the Two Types of
Metallacyclic Compounds III and VIII
cycloheptenyl complexes 8 and 8′ (both regioisomers) was
established by comparison of the analytical and NMR
spectroscopic data with those of a sample synthesized
previously by a different route.12d The minor component 9
could not be isolated, but the NMR spectra were consistent
with the formation of a complex with a Si−CH3 activated ligand
as found in 7a,b.
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289.1 (L-Npy), not observed (Npy). IR (Nujol, NaCl): ν 1586 s, 1491
sh, 1465 s, 1378 m, 1308 w, 1246 s, 1143 s, 1085 w, 1059 w, 1031 s,
997 w, 937 s, 907 w, 856 s, 787 m, 770 m, 747 s, 720 m, 693 m, 671 w
cm−1. Anal. Calcd for C45H61N7SSi2Zr: C, 61.46; H, 6.99; N, 11.15.
Found: C, 61.54; H, 6.99; N, 11.11.
thought to be initiated by rupture of the Zr−C bond in the
metallacycle I (the [2 + 2] cycloaddition product of hydrazide
+ allene), H atom abstraction from the silyl group results in the
formation of the cyclic intermediate II, which in turn undergoes
N−N bond cleavage and C−N coupling to give the
metallacycle III.12d On the other hand, the rupture of the
Zr−C bond may be associated with transfer of the NPh2 to the
metal and C−N coupling (IV) to give the aziridinato−Zr
species V, which undergoes a 1,3-sigmatropc H shift to give the
metalated azirinate VI. In a detailed computational study of the
Zr catalytic indole formation published recently by us,12e this
species has been invoked as a key intermediate leading to the
type VIII metallacycles.
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Preparation of [Zr(N2 Npy)(κ2N,S-SC(NMes)NNPh2)(py)]
TBS
(2b). To a stirred solution of [Zr(N2 Npy)(NNPh2)(py)] (1a;
(800 mg, 1.08 mmol) in toluene (20 mL) was added a solution of
mesityl isothiocyanate (136 mg, 1.08 mmol) in toluene (1 mL). The
reaction mixture was stirred overnight at room temperature and
filtered, and the volatiles were removed under reduced pressure. The
crude product was washed with pentane (3 × 5 mL) and dried in
vacuo to yield 920 mg (93%) of yellow 2b. Single crystals for X-ray
diffraction were grown from a saturated toluene solution at room
1
temperature. H NMR (600.13 MHz, THF-d8, 296 K): δ −0.76, 0.38
(s, 6 H, Si(CH3)2), 0.71 (s, 18 H, Si-C(CH3)3), 1.43 (CH3), 1.82 (s, 6
H, o-Mes-CH3), 2.13 (s, 3 H, p-Mes-CH3), 3.41 (bs, 2 H, CHH), 3.50
CONCLUSIONS
■
2
3
In this work we reported the syntheses and structural
characterization of [2 + 2] cycloaddition products derived
from hydrazinediido complexes of the heavier group 4 metals
and allenes or heteroallenes. Thermolysis of these compounds
led to rearrangement and a variety of C−H activation and C−C
and C−N coupling products. In particular, the formation of
complexes such as 7a,b and 9 is unprecedented. This and the
observation that the reactivity differs significantly from that of
the related titanium systems justifies further investigation into
the reactivity of zirconium and hafnium hydrazido complexes.
(d, JHH = 12.6 Hz, 2 H, CHH), 6.56 (s, 2 H, m-HMes), 6.73 (t, J(p-
HPhm-HPh) = 7.2 Hz, 2 H, p-HPh), 7.06 (bs, 4 H, m-HPh), 7.16−7.37
3
(m, 6 H, o-HPh, m-Hpy), 7.41 (t, J(H5pyH6py/H4py) = 6.4 Hz, 1 H,
3
H5py), 7.66 (d, J(H3pyH4py) = 8.0 Hz, 1 H, H3py), 7.75 (bs, 1 H, p-
Hpy), 7.97 (dt, 3J(H4pyH3py/H5py) = 7.9 Hz, 1 H, H4py), 8.79 (bs, 2 H,
o-Hpy), 9.23 (d, J(H6pyH5py) = 5.0 Hz, 1 H, H6py). 13C{1H} NMR
3
(150.90 MHz, THF-d8, 296 K): δ −5.0, −1.4 (Si(CH3)2), 19.8 (o-
CH3-Mes), 21.2 (p-CH3-Mes), 21.6 (Si-C(CH3)3), 25.6 (C-CH3), 28.5
(Si-C(CH3)3), 48.1 (C-CH3), 65.1 (CH2), 120.8 (p-CPh), 121.1 (m-
Cpy), 123.5 (C5py), 124.0 (C3py), 124.8 (p-Cpy), 128.4 (m-CMes), 128.6
(m-CPh), 129.3 (p-CMes), 130.3 (o-CMes), 140.0 (C4py), 147.5 (i-CMes),
149.2 (C6py), 149.2 (i-CNPh), 151.5 (o-Cpy), 157.9 (NCS), 161.6
(C2py). 29Si{1H} NMR (79.45 MHz, THF-d8, 296 K): δ 1.48
EXPERIMENTAL SECTION
■
t
(Si(CH3)2 Bu). 15N NMR (60.82 MHz, THF-d8, 296 K): δ 121.5
All manipulations of air- and moisture-sensitive materials were
performed under an inert atmosphere of dry argon using standard
Schlenk techniques or by working in a glovebox (Unilab-2000, M.
Braun). Argon was dried over phosphorus pentoxide (Sicapent, Merck
Chemicals). Solvents were dried over sodium (toluene, methyl
cyclohexane), potassium (hexane), or sodium/potassium alloy
(pentane), distilled, and degassed prior to use. Deuterated solvents
were dried over potassium (C6D6, THF-d8), vacuum-distilled, and
stored in Teflon valve ampules under argon. The hydrazinediido
t
(NPh2), 188.5 (N-Si(CH3)2 Bu), 209.1 (Zr-NCS), 245.2 (Mes-NCS),
289.3 (L-Npy), not observed (Npy). IR (Nujol, NaCl): ν 1579 s, 1463 s,
1377 s, 1303 w, 1260 s, 1169 m, 1146 m, 1095 m, 1022 s, 932 w, 832
m, 800 s, 722 w, 691 cm−1. Anal. Calcd for C68H67N7SSi2Zr·0.75C7H8:
C, 64.56; H, 7.43; N, 9.90. Found: C, 64.59; H, 7.41; N, 9.58.
TBS
Preparation of [Zr(N2 Npy)(κ2N,S-SC(NNPh2)NPh)] (3). To
TBS
a stirred solution of [Zr(N2 Npy)(NNPh2)(py)] (1a; 700 mg, 0.94
mmol) in toluene (20 mL) was added a solution of phenyl
isothiocyanate (123 mg, 0.94 mmol) in toluene (1 mL). The reaction
mixture was stirred overnight at room temperature and then heated to
60 °C for 5 h. After it was cooled, the reaction mixture was filtered and
the volatiles were removed under reduced pressure. The crude product
was washed with pentane (3 × 5 mL), recrystallized from cold (−78
°C) pentane, and dried in vacuo to yield 620 mg (70%) of 3 as a
TBS
TBS
complexes [Zr(N2 Npy)(NNPh2)(py)] (1a) and [Hf(N2 Npy)-
(NNPh2)(py)] (1b) were prepared according to published proce-
dures.13,17 All other reagents were obtained from commercial sources
and used as received unless explicitly stated otherwise. All liquid
reagents were degassed prior to use.
TBS
Preparation of [Zr(N2 Npy)(κ2N,S-SC(NPh)NNPh2)(py)]
TBS
(2a). To a stirred solution of [Zr(N2 Npy)(NNPh2)(py)] (1a; 800
1
yellow solid. H NMR (600.13 MHz, THF-d8, 296 K): δ −0.25, 0.14
mg, 1.08 mmol) in toluene (20 mL) was added a solution of phenyl
isothiocyanate (140 mg, 0.93 mmol) in toluene (1 mL). The reaction
mixture was stirred overnight at room temperature and filtered, and
the volatiles were removed under reduced pressure. The crude product
was washed with pentane (3 × 5 mL) and dried in vacuo to yield 800
mg (85%) of 2a as a yellow solid. Single crystals for X-ray diffraction
were grown from a saturated toluene solution at room temperature. 1H
NMR (600.13 MHz, THF-d8, 296 K): δ −0.70, 0.33 (s, 6 H,
Si(CH3)2), 0.65 (s, 18 H, Si−C(CH3)3), 1.34 (CH3), 3.35, (bs, 2 H,
(s, 6 H, Si(CH3)2), 0.60 (s, 18 H, Si−C(CH3)3), 1.57 (CH3), 3.30, (d,
2JHH = 13.0 Hz, 2 H, CHH), 4.05 (d, 2JHH = 13.0 Hz, 2 H, CHH), 6.70
3
4
(tt, J(p-HPhm-HPh) = 7.3 Hz, J(p-HPho-HPh) = 1.2 Hz, 2 H, p-HPh),
3
4
6.86 (tt, Jp-HPhNCSm-HPhNCS) = 7.4 Hz, J(p-HPhNCSo-HPhNCS) = 1.1
Hz, 1 H, p-HPhNCS), 7.07 (m, 4 H, m-HPh), 7.18 (m, 2 H, m-HPhNCS),
7.22 (dd, 3J(o-HPhm-HPh) = 7.6 Hz, 4J(o-HPhp-HPh) = 1.2 Hz, 4 H, o-
HPh), 7.50 (dt, = 3J(H5pyH6py/H4py) = 6.6 Hz, 4J(H5pyH3py) = 1.0 Hz,
1 H, H5p3y), 7.68 (d, 3J(o-HPhNCSm-HPhNCS) = 8.0 Hz, 2 H, o-HPhNCS),
3
2
7.77 (d, J(H3pyH4py) = 8.0 Hz, 1 H, H3py), 8.09 (dt, J(H4pyH3py/
CHH), 3.46 (d, JHH = 13.5 Hz, 2 H, CHH), 6.67−6.73 (m, 6 H, p-
H5py) = 7.8 Hz, 4J(H4pyH6py) = 1.7 Hz, 1 H, H4py), 8.98 (d,
3J(H6pyH5py) = 5.1 Hz, 1 H, H6py). 13C{1H} NMR (150.90 MHz,
THF-d8, 296 K): δ −4.7, −4.0 (Si(CH3)2), 20.9 (Si-C(CH3)3), 25.8
(C-CH3), 27.9 (Si-C(CH3)3), 49.0 (C-CH3), 63.9 (CH2), 120.4 (p-
CPh), 120.6 (o-CPh), 122.4 (p-CPhNCS), 123.3 (C3py), 124.1 (C5py),
125.2 (o-CPh‑NCS), 128.8 (m-CPh), 129.0 (m-CPhNCS), 142.0 (C4py),
149.3 (i-CPhNCS), 149.6 (i-CNPh), 148.3(C6py), 161.5 (C2py), 168.1
(NCS);29Si {1H} NMR (79.45 MHz, THF-d8, 296 K): δ 2.18
HPh, p-HPhNCS), 6.98 (t, 3J(m-HPhNCS/o-HPhNCS/p-HPhNCS) = 7.7 Hz, 2
H, m-HPhNCS), 7.00−7.20 (m, 10 H, o-HPh, m-HPh, o-HPhNCS), 7.24
3
(bs, 2 H, m-Hpy), 7.42 (t, J(H5pyH6py/H4py) = 6.4 Hz, 1 H, H5py),
7.64 (d, 3J(H3pyH4py) = 8.0 Hz, 1 H, H3py), 7.74 (bs, 1 H, p-Hpy), 7.96
(dt, 3J(H4pyH3py/H5py) = 7.9 Hz, 4J(H4pyH6py) = 1.5 Hz, 1 H, H4py),
3
8.74 (bs, 2 H, o-Hpy), 9.30 (d, J(H6pyH5py) = 5.5 Hz, 1 H, H6py).
13C{1H} NMR (150.90 MHz, THF-d8, 296 K): δ −4.7, −1.5
(Si(CH3)2), 21.9 (Si-C(CH3)3), 26.1 (C-CH3), 28.8 (Si-C(CH3)3),
48.5 (C-CH3), 65.4 (CH2), 121.0−123.9 (CAr), 124.0 (C5py), 124.4
(C3py), 125.2 (m-Cpy), 128.1−130.3 (CAr), 140.7 (C4py), 149.0 (i-
CPh‑NCS), 149.5 (C6py), 151.9 (o-Cpy), 152.5 (i-CNPh), 159.4 (NCS),
162.0 (C2py). 29Si{1H} NMR (79.45 MHz, THF-d8, 296 K): δ 1.88
t
(Si(CH3)2 Bu). 15N NMR (60.82 MHz, THF-d8, 296 K): δ 129.9
t
(NPh2), 194.0 (Ph-NCS), 203.2 (N-Si(CH3)2 Bu), 271.2 (Zr-NCS)
280.1 (L-Npy). IR (Nujol, NaCl) ν 1686 m, 1464 s, 1377 s, 1306 w,
1260 m, 1215 w, 1153 w, 1087 m, 1021 s, 895 w, 850 m, 821 m, 801
m, 733 w, 722 w, 692 w, 669 w cm−1. Anal. Calcd for C40H56N6SSi2Zr:
C, 60.03; H, 7.05; N, 10.50. Found: C, 60.10; H, 6.79; N, 10.96.
t
(Si(CH3)2 Bu). 15N NMR (60.82 MHz, THF-d8, 296 K): δ 129.8
t
(NPh2), 189.9 (N-Si(CH3)2 Bu), 209.5 (Zr-NCS), 244.6 (Ph-NCS),
3350
dx.doi.org/10.1021/om300143h | Organometallics 2012, 31, 3346−3354

Organometallics
Article
TBS
Preparation of [Zr(N2 Npy)(κ2N,C-N(NPh2)CH2CCH(Ph))-
(300 mg, 0.40 mmol) in toluene (20 mL) was added a solution of
cyclohexyl allene (60 μL, 0.40 mmol) in toluene (2 mL). The reaction
mixture was stirred for 16 h at room temperature and filtered, and the
volatiles were removed under reduced pressure. The resulting yellow
solid was washed with hexane (3 × 5 mL) before drying in vacuo to
TBS
(py)] (4a). To a stirred solution of [Zr(N2 Npy)(NNPh2)(py)]
(400 mg, 0.54 mmol) in toluene (20 mL) was added a solution of
phenyl allene (62 mg, 0.54 mmol) in toluene (2 mL). The reaction
mixture was stirred for 16 h at room temperature and filtered, and the
volatiles were removed under reduced pressure. The resulting yellow
solid was washed with hexane (3 × 3 mL) before drying in vacuo to
TBS
yield 200 mg (44%) of [Zr(N2 Npy)(κ2N,C-N(NPh2)CH2C
1
CH(Cy))(py)] as a yellow solid. H NMR (600 MHz, C6D6, 296
yield 320 mg (95%) of [Zr(N2 Npy)(κ2N,C-N(NPh2)CH2C
TBS
K): δ −0.69, 0.52 (s, 6 H, Si(CH3)2), 0.82 (s, 3 H, CH3), 0.85 (s, 18
H, Si−C(CH3)3), 1.14−1.24 (m, 3 H, cy-CH2), 1.45−1.53 (m, 2 H,
cy-CH2), 1.59−1.67 (m, 1 H, cy-CH2), 1.74−1.81 (m, 2 H, cy-CH2),
1.88 (s, 2 H, ZrCH2), 1.97−2.05 (m, 2 H, cy-CH2), 2.63−2.72 (m, 1
H, cy-CH), 2.99 (bd, 2JHH = 12.9 Hz, 2 H, CHH), 3.25 (d, 2JHH = 12.9
Hz, 2 H, CHH), 4.35 (d, 3JHH = 8.5 Hz 1 H, CCH), 6.54−6.59 (m,
2 H, m-Hpy), 6.65 (t, 3J(H5pyH4py/H6py) = 6.2 Hz, 1 H, H5py), 6.79 (t,
CH(Ph))(py)] (4a) as a yellow solid. Single crystals for X-ray
diffraction were grown from a methylcyclohexane/toluene (1/1)
1
solution at room temperature. H NMR (600 MHz, C6D6, 296 K): δ
−0.73, 0.45 (s, 6 H, Si(CH3)2), 0.80 (s, 3 H, CH3), 0.81 (s, 18 H, Si−
C(CH3)3), 2.24 (s, 2 H, ZrCH2), 3.00 (bd, JHH = 12.5 Hz, 2 H,
2
2
CHH), 3.24 (d, JHH = 12.5 Hz, 2 H, CHH), 5.77 (s, 1 H, CCH),
3
3
3
3J(m-HPho-HPh/p-HPh) = 7.2 Hz, 4 H, m-HPh), 6.87 (d, J(H3pyH4py)
6.56 (t, J(p-Hpym-Hpy) = 6.2 Hz, 2 H, m-Hpy), 6.61 (t, J(H5pyH4py/
H6py) = 6.4 Hz, 1 H, H5py), 6.76−6.87 (m, 5 H, H3py, m-Hpy, p-HPh),
6.91 (t, 3J(p-HPhCHm-HPhCH) = 7.2 Hz, 1 H, p-HPhCH), 7.07 (t,
3J(H4pyH3py/H5py) = 7.8 Hz, 1 H, H4py), 7.12−7.16 (m, 4 H, m-HPh),
7.25 (t, 3J(m-HPhCHo-HPhCH/p-HPhCH) = 7.8 Hz, 2 H, m-HPhCH), 7.40
(t, 3J(o-HPhm-HPh) = 7.8 Hz, 4 H, o-HPh), 7.76 (t, 3J(o-HPhCHm-
HPhCH) = 7.8 Hz, 2 H, o-HPhCH), 8.92 (bs, 2 H, o-Hpy), 9.09 (d,
3J(H6pyH5py) = 5.0 Hz, 1 H, H6py). 13C{1H} NMR (150 MHz, C6D6,
296 K): δ −5.5, −2.4 (Si(CH3)2), 20.9 (Si-C(CH3)3), 24.9 (C-CH3),
28.0 (Si-C(CH3)3), 46.5 (C-CH3), 49.2 (ZrCH2), 63.9 (CH2), 93.1
((Ph)HCC), 119.3 (o-CPh), 120.0 (p-CPh), 121.1 (p-CPh−CH), 122.0,
122.1 (C3py, C5py), 123.6 (m-Cpy), 127.1 (o-CPhCH), 128.0 (p-CPhCH),
128.7 (m-CPh), 137.9 (p-Cpy), 138.3 (C4py), 143.7 (i-CPhCH), 147.1
(C6py), 147.2 (i-CPh), 151.0 (o-Cpy), 158.2 ((Ph)HCC), 160.4
3
= 7.2 Hz, 1 H, H3py), 7.09 (t, J(H4pyH3py/H5py) = 7.6 Hz, 1 H,
H4py), 7.13−7.17 (m, 4 H, m-HPh), 7.39 (t, 3J(o-HPhm-HPh) = 7.8 Hz,
3
4 H, o-HPh), 8.94 (bs, 2 H, o-Hpy), 9.11 (d, J(H6pyH5py) = 5.3 Hz, 1
H, H6py). 13C{1H} NMR (150 MHz, C6D6, 296 K): δ −5.4, −2.4
(Si(CH3)2), 21.0 (Si-C(CH3)3), 25.0 (C-CH3), 27.1 (cy-CH2), 27.4
(cy-CH2), 28.1 (Si−C(CH3)3), 36.3 (cy-CH2, cy-CH), 45.9 (ZrCH2),
46.5 (C-CH3), 63.9 (CH2), 97.1 ((cy)HCC), 119.2 (o-CPh), 119.5
(p-CPh,), 121.7 (C5py), 121.9 (C3py), 123.5 (m-Cpy), 128.4 (m-CPh),
137.8 (C4py), 137.9 (p-Cpy),147.2 (i-CPh), 147.5 (C6py), 149.3
((cy)HCC), 151.0 (o-Cpy), 160.6 (C2py). 29Si{1H} NMR (80
t
MHz, C6D6, 296 K): δ 0.39 (Si(CH3)2 Bu). 15N NMR (60 MHz,
t
C6D6, 296 K): δ 123.9 (NPh2), 172.0 (N-Si(CH3)2 Bu), 220.6 (Zr-
NC), 293.6 (L-Npy), not observed (Npy). IR (Nujol, NaCl): ν 1626 m,
1600 m, 1585 m, 1498 sh, 1463 s, 1377 s, 1247 m, 1161 w, 1085 w,
1036 m, 885 w, 846 s, 826 m, 771 w, 740 m, 722 w, 691 w, 659 cm−1.
Anal. Calcd for C47H64N6Si2Zr: C, 65.61; H, 7.50; N, 9.77. Found: C,
65.21; H, 7.40; N, 9.78.
t
(C2py). 29Si{1H} NMR (80 MHz, C6D6, 296 K): δ 0.37 (Si(CH3)2 Bu).
15N NMR (60 MHz, C6D6, 296 K): δ 121.4 (NPh2), 177.2 (N-
t
Si(CH3)2 Bu), 223.0 (Zr-NC), 291.6 (L-Npy), not observed (Npy). IR
(Nujol, NaCl): ν 2725 w, 2669 s, 1607 sh, 1574 s, 1556 s, 1463 s, 1328
sh, 1247 w, 1174 m, 1029 m, 953 w, 891 w, 844 s, 770 w, 722 s, 692 m
cm−1. Anal. Calcd for C47H64N6Si2Zr: C, 65.61; H, 7.50; N, 9.77.
Found: C, 65.21; H, 7.40; N, 9.78.
TBS
Preparation of [Hf(N2 Npy)(κ2N,C-N(NPh2)CH2CCH(Cy))-
TBS
(py)] (5b). To a stirred solution of [Hf(N2 Npy)(NNPh2)(py)]
(1b; 800 mg, 0.96 mmol) in toluene (60 mL) was added cyclohexyl
allene (117 mg, 0.96 mmol). The reaction mixture was stirred
overnight at room temperature and filtered, and the volatiles were
removed under reduced pressure. The resulting yellow solid was
washed with pentane (2 × 5 mL) before drying in vacuo to yield 610
TBS
Preparation of [Hf(N2 Npy)(κ2N,C-N(NPh2)CH2CCH(Ph))-
TBS
(py)] (4b). To a stirred solution of [Hf(N2 Npy)(NNPh2)(py)]
(1b; 200 mg, 0.24 mmol) in toluene (20 mL) was added phenyl allene
(27 mg, 0.24 mmol). The reaction mixture was stirred overnight at
room temperature and filtered, and the volatiles were removed under
reduced pressure. The resulting yellow solid was washed with pentane
(2 × 5 mL) before drying in vacuo to yield 94 mg (41%) of
TBS
mg (67%) of [Hf(N2 Npy)(κ2N,C-N(NPh2)CH2CCH(Cy))(py)]
(5b) as a yellow solid. Single crystals for X-ray diffraction were grown
1
from a hexane solution at room temperature. H NMR (C6D6, 600.13
TBS
[Hf(N2 Npy)(κ2N,C-N(NPh2)CH2CCH(Ph))(py)] (4b) as a
MHz, 296 K): δ −0.70 (s, 6 H, Si(CH3)2), 0.49 (s, 6 H, Si(CH3)2),
0.82 (s, 3 H, C−CH3), 0.86 (s, 18 H, Si-C(CH3)3), 1.24−1.28 (m, 3
H, cy-CH2), 1.47−1.54 (m, 2 H, cy-CH2), 1.62−1.64 (m, 1 H, cy-
CH2), 1.76−1.79 (m, 4 H, Hf-CH2, cy-CH2), 2.02−2.04 (m, 2 H, cy-
1
yellow solid. H NMR (C6D6, 600.13 MHz, 296 K): δ −0.72 (s, 6
H, Si(CH3)2), 0.41 (s, 6 H, Si(CH3)2), 0.80 (s, 3 H, C-CH3), 0.82 (s,
18 H, Si-C(CH3)3), 2.14 (s, 2 H, Hf-CH2), 2.90−3.11 (m, 2 H,
2
2
CHaHb), 3.40 (d, JHH = 12.8 Hz, 2 H, CHaHb), 5.90 (s, 1 H, C
CH2), 2.71−2.73 (m, 1 H, cy-CH2), 3.00 (bd, JHH = 12.3 Hz, 2 H,
CHaHb), 3.40 (d, 2JHH = 12.7 Hz, 2 H, CHaHb), 4.47 (d, 1 H, 3J(HHcy)
= 7.71 Hz, CCH), 6.57−6.59 (m, 2 H, m-Hpy′), 6.63−6.66 (m, 1 H,
H5py), 6.78−6.86 (m, 4 H, p-HPh, p-Hpy′, H3p3y), 7.08−7.10 (m, 1 H,
H4py), 7.16−7.18 (m, 4 H, m-HPh), 7.39 (d, JHH = 7.2 Hz, 4 H, o-
CH), 6.56−6.60 (m, 2 H, m-Hpy′), 6.60−6.65 (m, 1 H, H5py), 6.78−
6.86 (m, 4 H, H3py, p-Hpy′, p-HPh), 6.93 (t, 3J(HpHm) = 7.2 Hz, 1 H, p-
HPh′), 7.00−7.12 (m, 1 H, H4py), 7.13−7.16 (m, 4 H, m-HPh), 7.27 (t,
3J(HpHm) = 7.5 Hz, 2 H, m-HPh), 7.40 (d, 3J(HoHm) = 5.5 Hz, 4 H, o-
3
HPh), 8.96 (d, 2 H, 3J(o-Hm-H) = 3.8 Hz, o-Hpy), 9.15−9.16 (m, 1 H,
HPh), 7.79 (d, J(HoHm) = 7.6 Hz, 2 H, o-HPh′), 8.97 (s, 2 H, o-Hpy′),
̀
9.14 (s, 1 H, H6py). 13C{1H} NMR (C6D6, 150.92 MHz, 296 K): δ
−5.4, −2.5 (Si(CH3)2), 21.3 (Si-C(CH3)3), 24.5 (C-CH3), 28.2 (Si-
C(CH3)3), 45.2 (C-CH3), 54.2 (Hf-CH2), 63.2 (CH2), 95.2 (C
CHPh), 119.5 (o-CPh), 120.2 (C3py, p-Cpy′, p-CPh), 121.4 (p-CPh),
122.1 (C3py, p-Cpy′, p-CPh), 122.4 (C5py), 123.8 (m-Cpy′), 127.4 (o-
CPh′), 128.7 (m-CPh), 137.8 (C3py, p-Cpy′, p-CPh), 138.2 (C4py), 143.5
(ipso-CPh′), 146.8 (C6py), 147.4 (i-CPh), 151.0 (o-Cpy′), 160.4 (C
CHPh), 165.3 (C2py). 15N NMR (C6D6, 60.84 MHz, 296 K): δ 123.4
(NPh2), 166.9 (N-TBS), 222.2 (Hf-NC), 281.5 (Npy′), 292.7 (Npy).
29Si{1H} NMR (C6D6, 79.45 MHz, 296 K): δ 1.6 (Si(CH3)2(tBu)). IR
(Nujol, NaCl, cm−1): ν 2926 vs, 2854 vs, 1923 w, 1579 m, 1464 s,
1378 m, 1328 w, 1258 m, 1174 m, 1098 w, 1024 m, 892 w, 851 w, 799
m, 743 m, 693 m, 627 w cm−1. Anal. Calcd for C47H64N6Si2Hf: C,
59.56; H, 6.81; N, 8.87. Found C, 59.61; H, 6.78; N, 9.31. Despite
repeated recrystallizations of 4b we were unable to obtain a more
accurate value for the nitrogen content.
H6py). 13C{1H} NMR (C6D6, 150.92 MHz, 296 K): δ −5.3, −2.5
(Si(CH3)2), 21.3 (Si(C(CH3)3), 24.6 (C-CH3), 27.1, 27.4 (cy-CH2),
28.2 (SiC(CH3)3), 36.3, 36.8 (cy-CH2), 45.2 (C-CH3), 50.8 (Hf-CH2),
63.3 (CH2), 99.2 (CCHCy), 119.4 (o-CPh), 119.6 (C3py, p-Cpy, p-
CPh), 122.9 (C3py, p-Cpy′, p-CPh), 122.0 (C5py), 123.6 (m-Cpy′), 137.5
(C3py, p-Cpy′, p-CPh), 137.9 (C4py), 143.4 (ipso-CPh), 146.9 (C6py),
147.7 (CCHCy), 150.9 (o-Cpy′), 160.4.4 (C2py). 15N NMR (C6D6,
60.84 MHz, 296 K): δ 123.1 (N(5)Ph2), 163.6 (N(1/2)-TBS), 220.4
(Hf-N(4)), 285.9 (Npy′), 293.6 (N(3)py). 29Si{1H} NMR (C6D6, 79.45
MHz, 296 K): δ 1.5 (Si(CH3)2(tBu)). IR (Nujol, NaCl): ν 2924 vs,
2854 vs, 1464 s, 1377 m, 1260 m, 1091 m, 1024 m, 852 w, 798 m, 585
w, 527 w cm−1. Anal. Calcd for C47H70N6Si2Hf: C, 59.19; H, 7.40; N,
8.81. Found: C, 59.01; H, 7.50; N, 8.66.
TBS
Preparation of [Zr(N2 Npy)(κ2N,C-N(NPh2)CH2CCH(Me))-
(py)] (6). Methyl allene was bubbled for 10 min through a stirred
TBS
solution of [Zr(N2 Npy)(NNPh2)(py)] (800 mg, 1.08 mmol) in
TBS
Preparation of [Zr(N2 Npy)(κ2N,C-N(NPh2)CH2CCH(Cy))-
toluene (30 mL) until the solution stayed orange. The reaction
mixture was stirred for an additional 2 h, and the volatiles were
TBS
(py)] (5a). To a stirred solution of [Zr(N2 Npy)(NNPh2)(py)]
3351
dx.doi.org/10.1021/om300143h | Organometallics 2012, 31, 3346−3354

Organometallics
Article
Table 2. Details of the Crystal Structure Determinations of 2a,b and 4a,b
2a·(toluene)
2b·(toluene)
4a
4b·(n-hexane)
C53H84HfN6Si2
formula
C52H69N7SSi2Zr
monoclinic
P21/n
C55H75N7SSi2Zr
monoclinic
P21/n
C47H64N6Si2Zr
monoclinic
P21/c
cryst syst
monoclinic
P21/n
space group
a/Å
11.596(3)
21.607(5)
20.596(5)
96.340(4)
5129(2)
11.392(6)
21.888(11)
22.235(11)
103.007(7)
5402(5)
11.140(5)
22.176(10)
19.373(8)
104.619(10)
4631(3)
11.179(6)
23.599(12)
20.213(10)
91.200(9)
5331(5)
4
b/Å
c/Å
β/deg
V/Å3
Z
4
4
4
Mr
971.60
1013.68
860.44
1039.93
2176
F000
2056
2152
1824
dc/Mg m−3
1.258
1.246
1.234
1.296
μ/mm−1
0.343
0.329
0.327
2.041
max, min transmissn factors
θ range/deg
0.7452, 0.6650
1.4 to 25.2
−13 to +13, 0−25, 0−24
0.7464, 0.6789
1.3 to 32.3
−17 to +16, 0−32, 0−33
0.7464, 0.6646
1.8 to 32.2
−16 to +15, 0−33, 0−28
0.7464, 0.6324
2.0 to 32.4
index ranges (indep set) h,k,l
no. of rflns
−16 to +16, 0−35, 0−29
measd
86 349
136 919
116 350
131 306
unique (Rint)
9145 (0.1504)
5844
18 314 (0.0445)
15 221
15 547 (0.0426)
12 868
18 031 (0.068)
14 468
obsd (I > 2σ(I))
no. of params refined
GOF on F2
580
619
516
572
1.107
1.030
1.058
1.034
R indices (F > 4σ(F)): R(F), Rw(F2)
R indices (all data): R(F), Rw(F2)
largest residual peaks/e Å−3
0.0540, 0.1292
0.1067, 0.1488
0.672, −0.705
0.0359, 0.0837
0.0485, 0.0925
0.691, −0.404
0.0322, 0.0759
0.0454, 0.0844
0.622, −0.385
0.0325, 0.0638
0.0499, 0.0708
2.802, −1.357
removed under reduced pressure. The resulting yellow solid was
CHH), 3.08 (d, 2JHH = 14.2 Hz, 1 H, CHH), 3.28 (d, 2JHH = 12.6 Hz, 1
2
2
washed with hexane (3 × 5 mL) before drying in vacuo to yield 300
H, CHH), 3.34 (d, JHH = 12.8 Hz, 1 H, CHH), 3.38 (d, JHH = 12.6
TBS
mg (35%) of [Zr(N2 Npy)(κ2N,C-N(NPh2)CH2CCH(Me))(py)]
Hz, 1 H, CHH), 3.95 (d, 2JHH = 12.8 Hz, 1 H, CHH), 4.68 (d, 3JHH
=
1
3
(6) as a yellow solid. H NMR (600 MHz, C6D6, 296 K): δ −0.66,
8.6 Hz, 1 H, CCH), 6.31 (t, J(H5pyH4py/H6py) = 6.1 Hz, 1 H,
H5py), 6.78 (d, 3J(H3pyH4py) = 8.0 Hz, 1 H, H3py), 6.86 (t, 3J(p-HPho-
mHPh) = 6.7 Hz, 2 H, p-HPh), 6.90 (t, 3J(H4pyH3py/H5py) = 7.5 Hz, 1
H, H4py), 8.98 (d, 3J(H6pyH5py) = 5.6 Hz, 2 H, H6py). 13C{1H} NMR
(150 MHz, C6D6, 296 K): δ −5.8, −4.3, −2.6 (Si(CH3)2), 19.6 (C
C-CH3), 20.1, 20.2 (Si-C(CH3)3), 22.7 (cy-CH2), 23.8 (C-CH3), 26.8
(cy-CH2), 27.0 (Si−C(CH3)3), 27.6 (cy-CH2), 28.2 (Si−C(CH3)3),
34.4 (cy-CH2), 36.7 (ZrCH2), 37.9 (cy-CH), 52.2 (C-CH3), 61.7, 63.3
(CH2), 109.5 ((cy)HCC), 119.8 (C3py), 120.7 (p-CPh), 121.9
(C5py), 130.1 (m-CPh), 139.4 (C4py), 147.4 ((cy)HCC), 150.2
(C6py), 151.7 (i-CPh), 164.5 (C2py), not observed (o-CPh). 29Si{1H}
0.50 (s, 6 H, Si(CH3)2), 0.84 (s, 18 H, Si-(CH3)3), 1.14 (s, 3 H, CH3),
3
1.87 (s, 2 H, ZrCH2), (d, JHH = 6.3 Hz, 3 H, CC-CH3), 3.05 (bd,
2JHH = 12.8 Hz, 2 H, CHH), 3.27 (d, = 12.8 Hz, 2 H, CHH), 4.59 (d,
3JHH = 6.3 Hz, 1 H, CCH), 6.57 (bs, 2 H, m-Hpy), 6.65 (t,
3
3J(H5pyH4py/H6py) = 6.0 Hz, 1 H, H5py), 6.79 (t, J(m-HPho-HPh/p-
HPh) = 7.1 Hz, 4 H, m-HPh), 6.81−6.87 (m, 3 H, p-Hpy, H3py), 7.08 (t,
3J(H4pyH3py/H5py) = 6.0 Hz, 1 H, H4py), 7.13−7.17 (m, 4 H, m-HPh),
7.42 (t, 3J(o-HPhm-HPh) = 7.6 Hz, 4 H, o-HPh), 8.90 (bs, 2 H, o-Hpy),
3
9.13 (d, J(H6pyH5py) = 5.3 Hz, 1 H, H6py). 13C{1H} NMR (150
MHz, C6D6, 296 K): δ −5.6, −2.7 (Si(CH3)2), 12.0 (CC-CH3), 20.8
(Si-C(CH3)3), 24.8 (C-CH3), 27.9 (Si-C(CH3)3), 45.3 (ZrCH2), 46.3
(C-CH3), 63.7 (CH2), 82.4 ((Me)HCC), 119.1 (o-CPh), 119.4 (p-
CPh), 121.5 (C5py), 121.8 (C3py), 123.3 (m-Cpy), 128.2 (m-CPh), 137.0
(p-Cpy), 137.7 (C4py), 147.0 (C6py), 147.5 (i-CPh), 150.7 (o-Cpy), 151.1
((Me)HCC), 160.4 (C2py). 29Si{1H} NMR (80 MHz, C6D6, 296
t
NMR (80 MHz, C6D6, 296 K): δ 2.84, 8.17 (Si(CH3)2 Bu). 15N NMR
t
(60 MHz, C6D6, 296 K): δ 173.7 (N-Si(CH3)2 Bu), 189.1 (N-
t
C(Me)C(Cy)), 191,4 (NPh2), 294.2 (N-Si(CH3)2 Bu), 282.1 (L-Npy).
IR (Nujol, NaCl): ν 1653 w, 1595 m, 1463 s, 1377 s, 1261 s, 1197 m,
1170 w, 1093 m, 1039 m 1012 sh, 894 w, 865 w, 801 s, 755 w, 722 m,
698 cm−1. Anal. Calcd for C42H65N5Si2Zr: C, 64.07; H, 8.32; N, 8.89.
t
K): δ 0.24 (Si(CH3)2 Bu). 15N NMR (60 MHz, C6D6, 296 K): δ 123.3
t
Found: C, 64.45; H, 8.20; N, 8.85.
(NPh2), 172.3 (N-Si(CH3)2 Bu), 222.8 (Zr-NC), 293.9 (L-Npy), not
TBS
Preparation of [Hf(κ4N,N,N,N-N2
N
NC(Me)CHCy)-
observed (Npy). IR (Nujol, NaCl): ν 1630 m, 1599 s, 1463 s, 1377 s,
1306 w, 1260 s, 1203 w, 1162 w, 1097 m, 1037 s, 950 w, 891 w 846 s,
825 s, 771 m, 722 s, 690 w, 658 w cm−1. Anal. Calcd for C, 63.18; H,
7.83; N, 10.53. Found: C, 62.80; H, 7.62; N, 9.41. Found: C, 62.97; H,
7.94; N, 10.10.
py
TBS
(NPh2)] (7b). A solution of [Hf(N2 Npy)(κ2-N,C-(CH2C(=CH-
(Cy))N(NPh2))(py)] (5b; 600 mg, 0.63 mmol) in toluene (60 mL)
was heated with stirring overnight to 80 °C. The reaction mixture was
filtered, the volatiles were removed under reduced pressure, and the
residue was dissolved in methylcyclohexane and then placed into a
−30 °C freezer. After 24 h, the yellow solid that formed was collected
by filtration and then dried in vacuo to yield 190 mg (34%) of 7b. 1H
NMR (C6D6, 600.13 MHz, 296 K): δ −0.13 (s, 3 H, Si(1)-CH3),
−0.09 (s, 3 H, Si(1)-CH3), 0.33 (s, 3 H, Si(2)-CH3), 0.92 (s, 9 H,
Si(2)-C(CH3)3), 0.95 (s, 9 H, Si(1)-C(CH3)3), 1.01 (s, 3 H, C−CH3),
1.20−1.28 (m, 3 H, cy-CH2), 1.30−1.58 (m, 2 H, cy-CH2), 1.62−1.69
(m, 1 H, cy-CH2), 1.72−1.81 (m, 2 H, cy-CH2), 1.86−1.95 (m, 2 H,
cy-CH2), 2.12 (s, 3 H, CC−CH3), 2.22−2.28 (m, 1 H, cy-CHipso),
TBS
Preparation of [Zr(κ4N,N,N,N-N2 NpyNC(Me)CHCy)(NPh2)]
TBS
(7a). A solution of [Zr(N2 Npy)(κ2NC-N(NPh2)CH2CCH(Cy)-
(py)] (5a; 800 mg, 1.07 mmol) in toluene (20 mL) was heated with
stirring for 5 h to 80 °C. The reaction mixture was filtered, and the
volatiles were removed under reduced pressure. The resulting yellow
solid was washed with pentane (3 × 5 mL) before drying in vacuo to
1
yield 600 mg (71%) of 7a as a yellow solid. H NMR (600 MHz,
C6D6, 296 K): δ −0.16, 0.05, 0.33, (s, 3 H, Si(CH3)2), 0.92, 0.94 (s, 9
H, Si-C(CH3)3), 1.04 (s, 3 H, CH3), 1.16−1.22 (m, 3 H, cy-CH2),
1.30−1.38 (m, 2 H, cy-CH2), 1.63−1.68 (m, 1 H, cy-CH2), 1.72−1.79
(m, 2 H, cy-CH2), 1.83−1.93 (m, 2 H, cy-CH2), 2.13 (s, 3 H, CC-
2
2.95−3.01 (m, 2 H, Si(2)-CH2), 3.41 (d, J(HH) = 12.5 Hz, 2 H,
2
CHaHb-N(2)), 3.49 (d, J(HH) = 12.5 Hz, 2 H, CHaHb-N(2)), 3.57
2
CH3), 2.21−2.62 (m, 1 H, cy-CH), 2.96 (d, JHH = 14.2 Hz, 1 H,
(d, 2J(HH) = 12.3 Hz, 2 H, CHaHb-N(1)), 4.04 (d, 2J(HH) = 12.3 Hz,
3352
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Organometallics
Article
3
2 H, CHaHb-N(1)), 4.51 (d, J(HcyH) = 8.5 Hz, 1 H, CC(Cy)H),
ACKNOWLEDGMENTS
■
6.32 (t, 3J(H5pyH6pyH4py) = 6.5 Hz, 1 H, H5py), 6.80 (d, 3J(H3pyH4py)
= 8.0 Hz, 1 H, H3py), 6.87 (t, J(o-HPhp-HPh) = 6.8 Hz, 2 H, p-HPh),
6.92 (t, J(H5pyH3pyH4py) = 7.8 Hz, 1 H, H4py), 7.14−7.28 (m, 8 H,
3
We thank the University of Heidelberg and the Deutsche
Forschungsgemeinschaft for funding (SFB 623, TP A7).
3
m-HPh, o-HPh), 9.51−9.52 (m, 1 H, H6py). 13C{1H} NMR (C6D6,
150.92 MHz, 296 K): δ −5.6 (Si(1)-CH3), −3.8, −2.2 (Si(2)-CH3),
20.1 (Si(2)-C(CH3)3), 20.3 (CC-CH3), 20.5 (Si(1)-C(CH3)3), 23.6
(C-CH3), 26.9 (cy-CH2), 27.0 (Si−C-(CH3)3), 27.2 (cy-CH2), 28.3
(Si−C-(CH3)3), 35.5 (d, J = 5.4 Hz, cy-CH2), 36.2 (Si(2)-CH2-N),
37.8 (cy-CipsoH), 52.0 (C-CH3), 61.1 (N(1)-CH2), 63.3 (N(2)-CH2),
109.8 (CC(Cy)H), 119.9 (C3py), 120.8 (p-CPh), 122.2 (o-/m-CPh),
122.3 (C5py), 139.0 (o-/m-CPh), 139.6 (C4py), 147.5 (CC-CH3),
150.3 (C6py), 151.7 (ipso-CPh), 164.8 (C2py). 15N NMR (C6D6, 60.84
MHz, 296 K): δ 166.2 (N(1)-TBS), 175.6 (N(2)-Si), 181.2 (Hf-
N(4)), 192.7 (Hf-N(5)Ph2), 281.8 (N(3)py′). 29Si{1H} NMR (C6D6,
79.45 MHz, 296 K): δ 4.52 (Si(1)(CH3)2(tBu)), 6.74 (Si(2)(CH3)-
(tBu)). IR (Nujol, NaCl) ν 2925 vs, 2854 vs, 1646 w, 1463 s, 1377 m,
1260 w, 1018 w, 902 w, 828 w, 800 w, 722 w cm−1. Anal. Calcd for
C42H64N6Si2Hf: C, 57.67; H, 7.49; N, 8.01. Found: C, 58.35; H, 8.04;
N, 7.34. Despite repeated recrystallizations we were unable to obtain
more accurate data for C and N.
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1
NMR spectroscopy. H NMR (600 MHz, C6D6, 296 K): δ −0.40,
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2
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X-ray Crystal Structure Determinations. Crystal data and
details of the structure determinations are given in Table 2. Full shells
of intensity data were collected at low temperature (T = 100 K) with a
Bruker AXS Smart 1000 CCD diffractometer (Mo Kα radiation,
graphite monochromator, λ = 0.710 73 Å). Data were corrected for air
and detector absorption and Lorentz and polarization effects;18
absorption by the crystal was treated with a semiempirical multiscan
method.19,20 The structures were solved by the heavy-atom method
combined with structure expansion by direct methods applied to
difference structure factors (complexes 4b and 2a)21 or by the charge
flip procedure (complexes 4a and 2b)22 and refined by full-matrix
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the disordered toluene molecule in the structure of 2b.23
ASSOCIATED CONTENT
Kubiak, R.; Muller, C.; Doye, S.; Wadepohl, H.; Gade, L. H. Dalton
̈
■
Trans. 2009, 4586.
S
* Supporting Information
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alkynes: (a) Leitch, D. C.; Turner, C. S.; Schafer, L. L. Angew. Chem.,
Int. Ed. 2010, 49, 6382. (b) Eisenberger, P.; Schafer, L. L. Pure Appl.
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CIF files giving crystallographic for 2a,b and 4a,b. This material
is available free of charge via the Internet at http://pubs.acs.org.
AUTHOR INFORMATION
■
(7) (a) Ward, B. D.; Maisse-Franco
Chem. Commun. 2004, 704. (b) Vujkovic, N.; Ward, B. D.; Maisse-
Francois, A.; Wadepohl, H.; Mountford, P.; Gade, L. H. Organo-
̧ is, A.; Mountford, P.; Gade, L. H.
Corresponding Author
̧
*Fax: (+49) 6221-545609. E-mail: lutz.gade@uni-hd.de.
metallics 2007, 26, 5522. (c) Vujkovic, N.; Lloret Fillol, J.; Ward, B. D.;
Wadepohl, H.; Mountford, P.; Gade, L. H. Organometallics 2008, 27,
2518.
Notes
The authors declare no competing financial interest.
3353
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