Reactivity of the yttrium alkyl carbene complex [Y(BIPM)(CH 2C6H5)(THF)] (BIPM = {C(PPh 2NSiMe3)2})2-: From insertions, substitutions, and additions to nontypical transformations

Article abstract of DOI:10.1021/om3010178

The yttrium alkyl carbene complex [Y(BIPM)(CH₂Ph)(THF)] (1; BIPM = {C(PPh₂NSiMe₃)₂})^2-) was treated with a series of unsaturated organic substrates, a bulky primary amine, and a group 1 metal alkyl to gauge and compare the reactivity of the Y=C _carbene and Y-C_alkyl bonds. Treatment of 1 with tert-butyl nitrile and 1-adamantyl azide gave the 1,2-migratory insertion products [Y(BIPM){NC(Bu^t)(CH₂Ph)}(THF)] (2) and [Y(BIPM){N ₃Ad-1,Bn-3-κ²N^1,3}(THF)] (3), respectively, with no reactivity observed at the Y=C double bond even when an excess of the relevant organic substrate was added. In contrast, the heteroallenes N,N′-dicyclohexylcarbodiimide and tert-butyl isocyanate reacted at both the Y=C_carbeneand Y-C_alkyl bonds of 1 to afford [Y{C(PPh₂NSiMe₃)₂[C(NCy) ₂]-κ⁴C,N,N′,N″}{C(NCy) ₂(CH₂Ph)-κ²N,N′}] (4) and [Y{C(PPh₂NSiMe₃)₂[C(O)(NBu^t)]- κ⁴C,N,N′,O}{C(O)(NBu^t)(CH₂Ph)- κ²N,O}] (5), respectively. 4 and 5 form regardless of the molar ratio of 1 to heteroallene, with no intermediates observed; thus, it is not clear if the [2 + 2]-cycloaddition or the 1,2-migratory insertion reaction occurs first. The addition of 2 equiv of tert-butyl isothiocyanate to 1 yields dimeric [Y(BIPMH){C(S)₂(NBu^t)-1-κS,2-κN:μ, κS′}]₂ (6), benzyl nitrile, and isobutylene by desulfurization and carbene-mediated deprotonation of a tert-butyl group of 1 equiv of heteroallene. The reaction between 1 and the bulky amine DippNH ₂ (Dipp = C₆H₃Prⁱ₂) gave [Y(BIPM)(NHDipp)(THF)] (7) by alkane elimination, with no reactivity observed at the Y=C_carbene bond. Finally, the addition of benzylpotassium to 1 afforded the yttriate polymer [Y(BIPM)(μ-η¹:η⁶- CH₂Ph)(μ-η¹:η²-CH ₂Ph)K]_∞ (8) by a formal carbopotassiation across the Y=C_carbene bond. Complexes 2-8 have been characterized by X-ray crystallography, multielement NMR spectroscopy, FTIR spectroscopy, and CHN microanalyses.

Full text of DOI:10.1021/om3010178

Article
pubs.acs.org/Organometallics
Reactivity of the Yttrium Alkyl Carbene Complex
[Y(BIPM)(CH2C6H5)(THF)] (BIPM = {C(PPh2NSiMe3)2})2−: From Insertions,
Substitutions, and Additions to Nontypical Transformations
David P. Mills, Lyndsay Soutar, Oliver J. Cooper, William Lewis, Alexander J. Blake,
and Stephen T. Liddle*
School of Chemistry, University of Nottingham, University Park, Nottingham NG7 2RD, U.K.
S
* Supporting Information
ABSTRACT: The yttrium alkyl carbene complex [Y(BIPM)-
(CH2Ph)(THF)] (1; BIPM = {C(PPh2NSiMe3)2})2−) was treated
with a series of unsaturated organic substrates, a bulky primary
amine, and a group 1 metal alkyl to gauge and compare the
reactivity of the YCcarbene and Y−Calkyl bonds. Treatment of
1 with tert-butyl nitrile and 1-adamantyl azide gave the 1,2-
migratory insertion products [Y(BIPM){NC(But)(CH2Ph)}-
(THF)] (2) and [Y(BIPM){N3Ad-1,Bn-3-κ2N1,3}(THF)] (3),
respectively, with no reactivity observed at the YC double
bond even when an excess of the relevant organic substrate was
added. In contrast, the heteroallenes N,N′-dicyclohexylcarbodii-
mide and tert-butyl isocyanate reacted at both the YCcarbene
and Y−Calkyl bonds of 1 to afford [Y{C(PPh2NSiMe3)2[C-
(NCy)2]-κ4C,N,N′,N″}{C(NCy)2(CH2Ph)-κ2N,N′}] (4) and [Y{C(PPh2NSiMe3)2[C(O)(NBut)]-κ4C,N,N′,O}{C(O)(NBut)-
(CH2Ph)-κ2N,O}] (5), respectively. 4 and 5 form regardless of the molar ratio of 1 to heteroallene, with no intermediates
observed; thus, it is not clear if the [2 + 2]-cycloaddition or the 1,2-migratory insertion reaction occurs first. The addition of 2
equiv of tert-butyl isothiocyanate to 1 yields dimeric [Y(BIPMH){C(S)2(NBut)-1-κS,2-κN:μ,κS′}]2 (6), benzyl nitrile, and
isobutylene by desulfurization and carbene-mediated deprotonation of a tert-butyl group of 1 equiv of heteroallene. The reac-
tion between 1 and the bulky amine DippNH2 (Dipp = C6H3Pri2) gave [Y(BIPM)(NHDipp)(THF)] (7) by alkane elimination,
with no reactivity observed at the YCcarbene bond. Finally, the addition of benzylpotassium to 1 afforded the yttriate polymer
[Y(BIPM)(μ-η1:η6-CH2Ph)(μ-η1:η2-CH2Ph)K]∞ (8) by a formal carbopotassiation across the YCcarbene bond. Complexes
2−8 have been characterized by X-ray crystallography, multielement NMR spectroscopy, FTIR spectroscopy, and CHN microanalyses.
The lanthanide bis(diphenylthiophosphinoyl)carbene com-
plexes [Ln{C(PPh2S)2}(μ-I)(THF)2]2 (Ln = Sm, Tm)7 and
[Li(THF)4]][Ln{C(PPh2S)2}2] (Ln = Sm, Tm)8 were found to
exhibit classical metallo-Wittig chemistry with benzophenone,
forming the alkene PPh2CC(PPh2S)2 and a metal oxide, although
in the case of the anionic carbene complexes the “open” metallo-
oxetane intermediates [Ln{C(PPh2S)2(Ph2CO)}2{Li(THF)}]
(Ln = Sm, Tm) could be isolated from the reaction mixtures.
Uranium(IV) carbenes incorporating the bis(diphenylthiophos-
phinoyl)methanediide ligand, exemplified by [U{C(PPh2S)2}-
(BH4)2(THF)2],9 and the uranyl(VI) carbene complex [UO2{C-
(PPh2S)2}(py)2]10 have been reported and were also shown to
react with ketones and aldehydes to generate the expected Wittig
products.
INTRODUCTION
■
Transition-metal carbene complexes have been studied ex-
tensively in recent years, chiefly as a direct consequence of their
applications in synthetic transformations.1 While investigations
into the chemistry of f-block carbenes are relatively few in num-
ber in comparison with their d-block counterparts,2 they promise
novel synthetic utility due to their highly polarized bonding.3
There has been a recent surge in interest in the preparation of
f-block carbene complexes that do not derive from stable free
carbenes, which are distinct from Lewis base adducts such as
f-block N-heterocyclic carbene complexes.4 The isolation of stable
early-metal carbenes with a formal MC double bond (also
referred to as geminal methanediides)5 represents a synthetic
challenge, as the highly polarized nature of the bonding requires
additional stabilizing features, such as sterically bulky phosphorus
substituents, to avoid polymetallic cluster formation.6 To date,
bis(diphenylthiophosphinoyl)methanediide ({C(PPh2S)2}2−) and
bis(diphenyliminophosphorano)methanediide ({C(PPh2NR)2}2−;
e.g., R = SiMe3, BIPM) ligands have found the most utility in
stabilizing lanthanide carbenes.2
The samarium(III) complex [Sm(BIPM)(NCy2)(THF)] was
the first structurally characterized lanthanide carbene complex
Special Issue: Recent Advances in Organo-f-Element Chemistry
Received: October 29, 2012
Published: December 18, 2012
© 2012 American Chemical Society
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to be reported,11 and a related neodymium(III) carbene com-
plex, [Nd{C(PPh2NPri)2}{HC(PPh2NPri)2}],12 has recently
been prepared, but no reactivity studies have been reported in
either case.
methanediide complex [Y(μ-BIPM){OC(CH2Ph)Ph2}]2
was observed. We have now extended our investigations
of 1 with a series of substrates including nitriles, amines,
heteroallenes and a group 1 metal alkyl in order to gain a
greater understanding of its reactivity, and our findings are
presented herein.
The entry point for our group into this field was the prepara-
tion of the yttrium alkyl carbene [Y(BIPM)(CH2SiMe3)(THF)],13
which was then extended to include [Ln(BIPM)(I)(THF)2]
(Ln = Y,14,15 Er15) and [Ln(BIPM)(CH2Ph)(THF)] (Ln = Y
(1);16 Ln = Dy, Er17). These complexes were prepared by
facile double deprotonation of BIPMH2 by the respective
lanthanide tri- or dialkyls, which is in contrast with the case for
[Sm(BIPM)(NCy2)(THF)], which required forcing conditions
to prepare. Thus, the yttrium complexes represent convenient
starting points from which to examine the reactivity of MC
double bonds. It is germane to note that this synthetic method-
ology was found to be inappropriate for the larger lanthanides,
with [Ln(BIPM)(BIPMH)] (Ln = La, Ce, Pr, Nd, Sm, Gd)
forming exclusively from the reactions between BIPMH2 and
the parent lanthanide trialkyls.17 It was later found that salt
metathesis strategies are more suitable for the preparation of
related carbene complexes of both the larger lanthanides, e.g.
[La{C(PPh2NMes)2}(I)(THF)3] (Mes = C6H2Me3-2,4,6),18
and uranium.19 DFT analysis of the bonding in [Y(BIPM)-
(CH2SiMe3)(THF)],13 [Y(BIPM)(I)(THF)2],15 and 116 sug-
gests that the bonding is predominantly ionic in these systems
and that the carbenes are essentially geminal methanediides
with two localized lone pairs of electrons. Although the bond-
ing was found to be similar for the three complexes, they
differ according to the ordering of their frontier orbitals, with a
carbene lone pair being the HOMO for [Y(BIPM)(CH2SiMe3)-
(THF)] and [Y(BIPM)(I)(THF)2], whereas the HOMO of 1 is
localized at the Y−Calkyl bond, which might vary its reactivity
profile.
A reactivity study of [Y(BIPM)(CH2SiMe3)(THF)] and [Y-
(BIPM)(I)(THF)2] with a selection of ketones has previously
been reported.20 While the expected 1,2-migratory insertion of
benzophenone into the Y−Calkyl bond of [Y(BIPM)(CH2SiMe3)-
(THF)] occurred to generate the alkoxide [Y(BIPM){OC-
(CH2SiMe3)Ph2}(THF)], the reaction of the YC bonds
of these complexes with ketones did not furnish Wittig-type
products. Instead, these reactions yielded a series of oxy-
methylbenzophenone and substituted isobenzofuran products
from carbene-mediated C−H activation and C−C and C−O
bond forming reactions. The reaction of [Y(BIPM)(I)(THF)2]
with PhCOMe was found to give the substituted cyclohexene
dypnopinacol via C−H activation, cyclotetramerization, and
dehydration. Both of these reactivity profiles are in contrast to
known transition-metal carbene chemistry and encourage fur-
ther investigations into the reactivity of lanthanide carbenes
with unsaturated organic substrates. The synthetic utility of
[Y(BIPM)(I)(THF)2] was further demonstrated in the prepara-
tion of the first Ga−Y bond in [Y(BIPM){Ga[N(Dipp)CH]2}-
(THF)2],14 which is part of a small family of f-element metal−
metal-bonded complexes in the literature.21
RESULTS AND DISCUSSION
■
The separate additions of tert-butyl nitrile and 1-adamantyl azide
to 1 afforded the 1,2-migratory insertion products [Y(BIPM)-
{NC(But)(CH2Ph)}(THF)] (2) and [Y(BIPM){N3Ad-1,Bn-3-
κ2N1,3}(THF)] (3), respectively (Scheme 1), in almost quan-
titative yield by 31P NMR spectroscopy but in low crystalline
yield due to their very high solubilities, which was a recurring
issue in this study (2, 14%; 3, 27%). The insertion of nitriles
into Y−C σ bonds to form ketimides is well-known,22 although
examples of corresponding f-element alkyl azide insertion
chemistry are surprisingly rare. The reaction of 1-adamantyl
azide with [U(Cp*)2(Me)2] also furnished a triazenido alkyl
complex, [U(Cp*)2{N3Ad-1,Me-3-κ2-N1,3}(Me)],23 and ger-
mane to this related triazenido complexes formed from the
reaction between 1-adamantyl azide and [M{OCMe2CH2[C-
(NCH2CH2NDipp)]}{N(SiMe3)2}2] (M = Y, Ce) by insertion
into the metal−carbene dative bond.24 In common with the
reactions of 1 with diphenyldiazene and benzophenone,16
the addition of further equivalents of tert-butyl nitrile and
1-adamantyl azide to 2 and 3 did not result in reaction at the
methanediide center. The formation of 2 and 3 was evidenced
1
initially by H NMR spectroscopy, with the benzyl methylene
proton resonance shifting downfield from the value observed
for 1 and no longer coupling with 89Y (δ 3.88 (2), 4.93 (3) and
2
2.78 (1) ppm; JYH for 1 = 1.6 Hz). These values are com-
parable to the respective corresponding resonances observed in
1
the H NMR spectra of [Y(BIPM){OC(CH2Ph)Ph2}(THF)]
(δ 4.04 ppm) and [Y(BIPM){N(Ph)N(Ph)(CH2Ph-κ2N,N′)}]
(δ 5.46 ppm).16 It is also straightforward to monitor the for-
mation of 2 by observation of the ketimide functional group in
the FTIR spectrum (CN stretch 1671 cm−1). However, the
2
31P{1H} NMR spectra of 2 (δ 3.60 ppm (d, JYP = 13.0 Hz))
2
and 3 (δ 3.89 ppm (d, JYP = 11.3 Hz)) are not markedly
2
different from the starting material 1 (δ 4.80 ppm (d, JYP
=
13.1 Hz)).16 Nonetheless, in the 13C{1H} NMR spectra the
ketimide carbon (δ 175.27 ppm (d, 2JYC = 8.1 Hz)) of 2, the
methylene singlet (2, δ 43.02 ppm; 3, δ 61.42 ppm) and
methanediide doublet of triplets (2, δ 51.36 ppm (JPC
=
152.0 Hz, JYC = 5.0 Hz); 3, δ 59.81 ppm (JPC = 185.1 Hz,
JYC = 4.0 Hz)) resonances of both complexes are diagnostic
of their formation and compare well to the correspond-
ing values reported for the yttrium ketimide [Y(Cp*)2-
{NC(But)(CH2C6H3Me2-3,5)}(NCBut)] (δ 168.96 ppm
(d, JYC = 9.8 Hz, CNY))22a and the yttrium carbene com-
2
plex [Y(BIPM){N(Ph)N(Ph)(CH2Ph-κ2-N,N′)}] (δ 60.00
(dt (JPC = 207.3 Hz, JYC = 5.0 Hz, CP2); 61.55 ppm
(CH2Ph)).16
A preliminary reactivity study of 1 has been published,16
with no reactivity at the formal YC double bond observed. 1
was shown to react separately with diphenyldiazene and ben-
zophenone to afford [Y(BIPM){N(Ph)N(Ph)(CH2Ph-κ2N,N′)}]
and [Y(BIPM){OC(CH2Ph)Ph2}(THF)], respectively, by
1,2-migratory insertion reactions at the Y−Calkyl bond.16
Further equivalents of diphenyldiazene or benzophenone
did not result in reaction at the methanediide center, but
in the case of the ketone dimerization to the bridging
The molecular structures of 2·C7H8 (Figure 1) and 3 (Figure 2)
were determined, and selected bond lengths and angles are
compiled in Table 1. These structures will be discussed together
for brevity. The BIPM ligands of both complexes adopt open-
book conformations, with typical intramolecular distances and
angles in the metallacycles and YCcarbene distances (2, 2.428(2) Å;
3, 2.482(5) Å) that confirm a methanediide formulation (cf.
YC = 2.357(3) Å for 1).16 The yttrium centers of both com-
plexes are coordinated by THF, with 2 being five-coordinate
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Scheme 1. Synthesis of 2−8
Figure 1. Molecular structure of 2·C7H8 with selective atom labeling. Displacement ellipsoids are set at the 40% probability level, and hydrogen
atoms and lattice solvent are omitted for clarity.
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Figure 2. Molecular structure of 3 with selective atom labeling. Displacement ellipsoids are set at the 40% probability level, and hydrogen atoms are
omitted for clarity.
and 3 six-coordinate according to the differing binding modes
of the remaining ligands and with the N(3)−N(4)−N(5)
triazenido fragment of 3 essentially orthogonal (96.7(6)°) to
the P2N2 plane of the BIPM scaffold. As expected, the Y(1)−
N(3) distance in 2 (2.165(2) Å) is shorter than the Y(1)−N(3)
(2.433(5) Å) and Y(1)−N(5) (2.407(5) Å) distances in 3. The
Y(1)−N(3) and N(3)−C(32) (1.245(4) Å) distances and
Y(1)−N(3)−C(32) angle (164.3(2)°) of 2 are remarkably sim-
ilar to the corresponding parameters observed for the related
imidazolin-2-iminato complex [Y{NC(NDippCH)2}(η8-C8H8)-
(THF)2] (Y−N = 2.163(2) Å; NC = 1.255(3) Å; Y−N−C =
163.51(19)°),25 which itself is considered to exhibit a remark-
ably short Y−N distance. Delocalization about the N(3)−
N(4)−N(5) framework of 3 (N−N = 1.316(6) Å mean,
N−N−N = 111.7(5)°) is evidenced by the intermediacy
of the N−N distances (idealized bond lengths from sum
of covalent radii: N−N = 1.42 Å, NN = 1.20 Å),26 which
compares well to the analogous metrics in the related com-
plex [Ce{OCMe2CH2[AdN3C(NCH2CH2NDipp)]-κ3O,N1,3}-
{N(SiMe3)2}2] (N−N = 1.319(4) Å mean, N−N−N =
109.29(7)°).24
Treatment of 1 with 2 equiv of the heteroallenes N,N′-
dicyclohexylcarbodiimide and tert-butyl isocyanate proceeded
by a [2 + 2]-cycloaddition and a 1,2-migratory insertion reac-
tion to afford [Y{C(PPh2NSiMe3)2[C(NCy)2]-κ4C,N,N′,N″}-
{C(NCy)2(CH2Ph)-κ2N,N′}] (4) and [Y{C(PPh2NSiMe3)2[C-
(O)(NBut)]-κ4C,N,N′,O}{C(O)(NBut)(CH2Ph)-κ2N,O}] (5),
respectively (Scheme 1). In common with the formation of 2
and 3, low-average crystalline yields of 4 (47%) and 5 (19%)
were obtained despite the reactions being adjudged to be
essentially quantitative by NMR spectroscopy. The 31P NMR
spectra exhibit a doublet for 4 (δ 17.96 ppm (2JYP = 4.4 Hz))
and a broad singlet for 5 (δ 20.57 ppm), both downfield of the
signals for 1 (δ 3.48 ppm (2JYP = 13.0 Hz))15 but comparable to
the signal for [Zr{C(PPh2NSiMe3)2[C(NCy)2]-κ4C,N,N′,N″}-
(Cl)2] (δ 21.0 ppm).27 It is not clear if the formations of 4 and
5 proceed initially by reaction at the YCcarbene or Y−Calkyl
sites, as no 1:1 products (1,2-migratory insertion or [2 + 2]-
cycloaddition) could be detected at any molar ratio employed.
Thus, when 1 equiv of substrate is reacted with 1, a 50% yield
of doubly reacted 4 or 5 is always observed, with 50% of 1 left
unconsumed. Varying the stoichiometry simply returns differ-
ent ratios of 4 or 5 and unreacted 1, which suggests that once
the heteroallene has reacted with 1 (be it by 1,2-migratory
insertion or [2 + 2]-cycloaddition), this activates it to a rapid
second reaction before the remaining heteroallene can react
with any remaining 1. This high reactivity is consistent with the
electrophilic carbon centers present in dicyclohexylcarbodii-
mide and tert-butyl isocyanate. [2 + 2]-cycloadditions of
heteroallenes to group 4 BIPM complexes have been observed
previously, although while the formations of [M{C-
(PPh2NSiMe3)2[C(NR)2]-κ4C,N,N′,N″}(Cl)2] (M = Zr, R =
Cy; M = Hf, R = p-tolyl)27 are analogous to that of 4, the
formations of [M{C(PPh2NSiMe3)2[C(O)(NAd)]-
κ4C,N,N′,N″}(Cl)2] (M = Zr, Hf, Ad = adamantyl, C10H15)27
are in contrast with that of 5, where the isocyanate has added
across the MC bond to form an M−O bond, rather than an
M−N bond. As with 2 and 3, the methylene resonances of the
benzyl group of 4 and 5 are shifted in their 1H (4, δ 3.85 ppm;
5, δ 3.64 ppm) and 13C (4, δ 34.82 ppm; 5, δ 41.99 ppm
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Table 1. Selected Bond Lengths (Å) and Angles (deg) for 2−8
2·C7H8
N(1)−Y(1)−N(2)
N(2)−Y(1)−O(1)
P(1)−N(1)−Y(1)
C(37)−N(4)−Y(1)
N(1)−P(1)−C(1)
P(1)−C(1)−P(2)
P(2)−C(1)−C(32)
C(32)−O(1)−Y(1)
N(4)−C(37)−O(2)
95.5(3)
101.3(3)
96.5(3)
N(1)−Y(1)−O(1)
N(4)−Y(1)−O(2)
P(2)−N(2)−Y(1)
C(37)−O(2)−Y(1)
N(2)−P(2)−C(1)
P(1)−C(1)−C(32)
C(1)−C(32)−O(1)
C(32)−C(1)−Y(1)
103.4(3)
56.4(3)
99.0(4)
97.9(8)
110.4(5)
116.9(7)
111.6(8)
83.5(6)
Y(1)−C(1)
Y(1)−N(2)
Y(1)−O(1)
C(1)−P(2)
2.428(2)
2.346(2)
2.3356(19)
1.659(3)
1.633(2)
1.541(4)
123.98(8)
93.43(10)
108.29(12)
164.3(2)
Y(1)−N(1)
Y(1)−N(3)
C(1)−P(1)
P(1)−N(1)
N(3)−C(32)
2.340(2)
2.165(2)
1.659(3)
1.630(2)
1.245(4)
87.2(7)
109.5(4)
122.8(6)
118.0(7)
107.3(5)
114.3(12)
P(2)−N(2)
C(32)−C(37)
N(1)−Y(1)−N(2)
P(2)−N(2)−Y(1)
N(2)−P(2)−C(1)
Y(1)−N(3)−C(32)
P(1)−N(1)−Y(1)
N(1)−P(1)−C(1)
P(1)−C(1)−P(2)
94.00(10)
107.93(12)
138.23(16)
6·3.5C7H8
Y(1)−C(1)
Y(1)−N(2)
Y(1)−S(2)
C(1)−P(1)
P(1)−N(1)
C(32)−N(3)
C(32)−S(2)
N(1)−Y(1)−N(2)
P(2)−N(2)−Y(1)
2.633(3)
Y(1)−N(1)
Y(1)−S(1)
Y(1)−N(3A)
C(1)−P(2)
P(2)−N(2)
C(32)−S(1)
2.393(2)
3
2.455(2)
2.9011(7)
1.748(3)
1.611(2)
1.304(3)
1.770(3)
107.46(8)
98.95(10)
2.7489(7)
2.482(2)
1.731(3)
1.600(2)
1.744(3)
Y(1)−C(1)
Y(1)−N(2)
Y(1)−N(5)
C(1)−P(1)
P(1)−N(1)
2.482(5)
2.324(5)
2.407(5)
1.660(6)
1.627(5)
1.315(6)
1.479(7)
126.31(16)
95.6(2)
Y(1)−N(1)
Y(1)−N(3)
Y(1)−O(1)
C(1)−P(2)
P(2)−N(2)
N(4)−N(5)
2.339(5)
2.433(5)
2.349(4)
1.649(6)
1.641(5)
1.317(6)
P(1)−N(1)−Y(1)
98.13(10)
96.60(16)
N(3)−N(4)
N(3)−C(32)
C(32A)−N(3A)−Y
(1)
N(1)−Y(1)−N(2)
P(2)−N(2)−Y(1)
N(2)−P(2)−C(1)
N(3)−N(4)−N(5)
N(4)−N(3)−Y(1)
P(1)−N(1)−Y(1)
N(1)−P(1)−C(1)
P(1)−C(1)−P(2)
N(4)−N(5)−Y(1)
N(5)−Y(1)−N(3)
95.1(2)
107.3(3)
138.6(4)
98.0(3)
C(32)−S(1)−Y(1)
S(1)−Y(1)−S(2)
N(1)−P(1)−C(1)
P(1)−C(1)−P(2)
86.73(9)
C(32)−S(2)−Y(1)
81.61(8)
122.2(2)
63.025(19) C(32)−N(3)−C(33)
107.77(12)
107.2(3)
111.7(5)
96.8(3)
N(2)−P(2)−C(1)
N(3)−C(32)−S(1)
S(1)−C(32)−S(2)
106.35(12)
130.0(2)
126.80(17)
53.50(16)
N(3)−C(32)−S(2) 115.3(2)
114.54(15)
4·C4H10O
7
Y(1)−C(1)
Y(1)−N(2)
Y(1)−N(5)
C(1)−P(1)
P(1)−N(1)
C(1)−C(32)
C(32)−N(4)
C(45)−N(6)
N(1)−Y(1)−N(2)
N(2)−Y(1)−N(3)
P(2)−N(2)−Y(1)
C(45)−N(6)−Y(1)
N(2)−P(2)−C(1)
P(1)−C(1)−C(32)
C(1)−C(32)−N(3)
C(32)−C(1)−Y(1)
C(45)−N(5)−Y(1)
2.716(4)
2.344(3)
2.434(3)
1.754(4)
1.616(3)
1.531(5)
1.300(5)
1.320(5)
112.38(11)
96.75(11)
99.94(15)
95.9(2)
Y(1)−N(1)
Y(1)−N(3)
Y(1)−N(6)
C(1)−P(2)
P(2)−N(2)
C(32)−N(3)
C(45)−N(5)
C(45)−C(46)
2.360(3)
2.345(3)
2.385(3)
1.750(4)
1.617(3)
1.378(5)
1.350(5)
1.530(5)
92.10(11)
100.53(15)
92.9(2)
Y(1)−C(1)
Y(1)−N(2)
Y(1)−O(1)
C(1)−P(2)
2.426(2)
Y(1)−N(1)
Y(1)−N(3)
C(1)−P(1)
P(1)−N(1)
2.3504(19)
2.2519(19)
1.665(2)
2.3233(19)
2.3546(16)
1.670(2)
1.6303(19)
P(2)−N(2)
1.6342(19)
116.28(7)
94.61(9)
N(1)−Y(1)−N(2)
P(2)−N(2)−Y(1)
N(1)−P(1)−C(1)
P(1)−C(1)−P(2)
P(1)−N(1)−Y(1)
C(32)−N(3)−Y(1)
N(2)−P(2)−C(1)
93.58(8)
145.43(17)
106.87(10)
107.68(10)
139.24(14)
N(1)−Y(1)−N(3)
P(1)−N(1)−Y(1)
C(45)−N(5)−Y(1)
N(1)−P(1)−C(1)
P(1)−C(1)−P(2)
P(2)−C(1)−C(32)
C(32)−N(3)−Y(1)
N(5)−C(45)−N(6)
C(45)−N(6)−Y(1)
8·2C7H8
Y(1)−C(1)
Y(1)−N(2)
Y(1)−C(39)
C(1)−P(2)
P(2)−N(2)
K(1)···C(2)
2.453(2)
2.359(2)
2.467(3)
1.672(2)
1.625(2)
3.118(2)
3.521(2)
3.567(2)
3.353(3)
3.421(3)
3.108(3)
3.368(3)
3.122(3)
126.05(7)
94.14(9)
108.59(11)
Y(1)−N(1)
Y(1)−C(32)
C(1)−P(1)
P(1)−N(1)
K(1)···C(1)
K(1)···C(3)
K(1)···C(5)
K(1)···C(7)
K(1)···C(33)
K(1)···C(35)
K(1)···C(37)
K(1A)···C(43)
2.357(2)
2.443(3)
1.671(2)
1.612(2)
2.953(2)
3.233(2)
3.672(2)
3.289(2)
3.520(3)
3.228(3)
3.175(3)
3.140(3)
109.49(17)
128.4(2)
114.6(3)
105.5(2)
115.3(3)
95.9(2)
110.26(17)
114.5(3)
111.6(3)
85.9(2)
92.9(2)
K(1)···C(4)
K(1)···C(6)
5
Y(1)−C(1)
Y(1)−N(2)
Y(1)−O(1)
Y(1)−O(3)
C(1)−P(2)
P(2)−N(2)
C(32)−N(3)
C(37)−N(4)
C(37)−C(42)
2.668(10)
2.356(8)
2.214(6)
2.517(10)
1.736(10)
1.596(9)
1.260(12)
1.436(18)
1.524(18)
Y(1)−N(1)
Y(1)−N(4)
Y(1)−O(2)
C(1)−P(1)
P(1)−N(1)
C(1)−C(32)
C(32)−O(1)
C(37)−O(2)
2.457(8)
2.343(10)
2.274(7)
1.738(10)
1.613(8)
1.523(13)
1.354(12)
1.157(14)
K(1)···C(28)
K(1)···C(34)
K(1)···C(36)
K(1)···C(38)
K(1A)···C(44)
N(1)−Y(1)−N(2)
P(2)−N(2)−Y(1)
N(2)−P(2)−C(1)
P(1)−N(1)−Y(1)
N(1)−P(1)−C(1)
P(1)−C(1)−P(2)
93.90(9)
108.37(11)
140.43(14)
3
2
(d, JYC = 3.0 Hz)) NMR spectra compared to 1 (1H, δ 2.78
ppm (2JYH = 1.6 Hz); 13C, δ 52.21 ppm (JYC = 24.2 Hz)). Fur-
ther analysis of the 13C{1H} NMR spectra of 4 and 5 allowed
assignment of the respective amidinate and amidate carbons (4,
108.1 Hz, JYC = 2.3 Hz), 156.85 ppm (t, JPC = 5.0 Hz)).
Carbodiimide and isocyanate insertions22d,28 into yttrium−
carbon σ bonds are common, and the values for the amidinate
and amidate resonances in the 13C NMR spectra may be com-
pared with typical examples such as [Y(PCp*){C(NPri)2-
(CH2SiMe3)2-κ2N,N′}2] (PCp* = 1,2,3-trimethyl-1H-
cyclopenta[l]phenanthrene) (δ 177.40 ppm) and [Y(PCp*)-
{C(O)(NSiMe3)(CH2SiMe3)-κ2N,O}2] (δ 188.54 ppm).28d
2
2
δ 175.98 ppm (d, JYC = 2.0 Hz); 5, δ 179.13 ppm (d, JYC
2.0 Hz)) and the two quaternary carbons in each complex that
derive from the [2 + 2]-cycloaddition reactions (4, δ 23.75 (dt,
JPC = 106.6 Hz, JYC = 3.1 Hz), 153.30 ppm; 5 δ 29.31 (dt, JPC
=
=
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Resonances of the other quaternary carbons in 4 and 5
compare well with those reported for [Zr{C(PPh2NSiMe3)2[C-
(NCy)2]-κ4C,N,N′,N″}(Cl)2] (δ 15.5 (t, JPC = 96.0 Hz), 148.7
ppm (bt, JPC = 4 Hz)).27
2
The molecular structures of 4·C4H10O (Figure 3) and 5
(Figure 4) were confirmed by single-crystal X-ray diffraction
Figure 4. Molecular structure of 5 with selective atom labeling.
Displacement ellipsoids are set at the 40% probability level, and
hydrogen atoms are omitted for clarity.
κ4C,N,N′,N″}(Cl)2] (C−N = 1.384(5) and 1.285(5) Å).27 A localized
C−N single bond (C(37)−N(4) = 1.436(18) Å) and CO
double bond (C(37)−O(2) = 1.157(14) Å) were also observed
in the amidate ligand of 5, in contrast to the corresponding
delocalized distances found in [Y(TpMe2)(Cp){C(O)(NPh)-
(CH2Ph)-κ2-N,O}2] (Tp = tris(pyrazolyl)borate) (C−N =
1.299(6) Å, C−O 1.276(6) Å).28e However, delocalization is
evident in the amidinate ligand of 4 (C−N range 1.320(5)−
1.350(5) Å) and these values compare well to the equivalent
distances observed in [Y(TpMe2)(Cp){C(NCy)2(CH2Ph)-
κ2N,N′}2] (C−N range 1.314(4)−1.340(4) Å).28e
Figure 3. Molecular structure of 4·C4H10O with selective atom
labeling. Displacement ellipsoids are set at the 40% probability level,
and hydrogen atoms and lattice solvent are omitted for clarity.
The reactions of 1 with heteroallenes was extended to tert-
butyl isothiocyanate, which was found to react in a 2:1 molar
ratio with 1 to afford a dimeric product, [Y(BIPMH){C(S)2-
(NBut)-1-κS,2-κN:μ,κS′}]2 (6), which incorporates two dithio-
carbonimidate ligands, in low (33%) yield (Scheme 1).
Variation of the reaction stoichiometry from a 1:1 to a 2:1
molar ratio of ButNCS to 1 did not lead to increased yields of 6.
It is noteworthy that Mindiola has reported that the reaction of
phenyl isothiocyanate with a titanium carbene proceeds via a
[2 + 2]-cycloaddition reaction,30 while Grubbs has disclosed
the desulfurization of phenyl isothiocyanate mediated by an
iridium carbene complex.31 However, the formation of 6
represents a novel mode of reactivity of isothiocyanates with
early metal carbenes. The desulfurization of isothiocyanates to
form dithiocarbonimidates mediated by transition-metal
complexes has been observed previously,32 but in all of these
examples a low-valent metal complex or intermediate is present
to mediate the reductive disproportionation of two isothiocya-
nate molecules, generally leading to the formation of the
dithiocarbonimidate and an isocyanide. This is not a viable
pathway for yttrium(III), which is typically redox-inert and
yttrium(II) complexes are only formed under highly reducing
conditions.33 Analysis of the reaction mixture by multinuclear
and are depicted here, with selected bond lengths and angles
given in Table 1. As with 2 and 3, the structures of 4 and 5 have
similar bulk properties, with the yttrium centers of both com-
plexes coordinated by one κ4-dianionic and one κ2-mono-
anionic ligand. Therefore, they will be discussed together,
although the yttrium center of 4 is five-coordinate and that of 5
is six-coordinate, as the smaller steric bulk of the tert-butyl
groups versus cyclohexyl groups allows the additional coordina-
tion of a THF molecule in 5. The propeller-shaped geometry of
the dianionic ligand systems, with N(1), N(2), and N(3) (4) or
N(1), N(2), and O(1) (5) at the vertices of approximate triangles
is comparable to that observed for [Zr{C(PPh2NSiMe3)2[C-
(NCy)2]-κ4C,N,N′,N″}(Cl)2]27 and the Y(1)−C(1) distances
(4, 2.716(4) Å; 5, 2.668(10) Å) and other intramolecular bond
lengths and angles are similar to related yttrium methanide
complexes.14,20,29 Localized single (4, C(32)−N(3) = 1.378(5) Å;
5, C(32)−O(1) = 1.354(12) Å) and double (4, C(32)−N(4) =
1.300(5) Å; 5, C(32)−N(3) = 1.260(12) Å) bonds are
observed in the dianionic ligand framework, and these are anal-
ogous to the related distances in [Zr{C(PPh2NSiMe3)2[C(NCy)2]-
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NMR spectroscopy revealed that a number of products are
formed in the reaction mixture, but only 6 could be isolated and
identified. The reaction is proposed to proceed as described in
Scheme 2, where initially 1,2-migratory insertion of tert-butyl
a broad singlet (δ 18.56 ppm) and two double doublets (δ 18.95
ppm (2JPP = 12.2 Hz, 2JYP = 6.7 Hz, 21.04 ppm, 2JPP = 12.2 Hz,
2JYP = 6.7 Hz)) which derive from the monomeric and dimeric
species. Germane to this observation, three signals are observed
in the 29Si NMR spectrum (δ −6.00, −4.69, and −3.66 ppm).
1
Although the methanide proton was not observed in the H
Scheme 2. Proposed Mechanism of Formation of 6
NMR spectrum of 6, the methanide carbon was observed in its
13C{1H} NMR spectrum (δ 14.90 ppm (t, JPC = 106.6 Hz)) but
the quaternary dithiocarbonimidate carbon was not observed.
The molecular structure of 6·3.5C7H8 was obtained and is
illustrated in Figure 5, and selected bond lengths and angles
can be found in Table 1. 6 is the first structurally characterized
example of a lanthanide dithiocarbonimidate complex and
exhibits a novel bridging binding mode for this ligand class, as
it additionally coordinates by a nitrogen lone pair.35 The
bis(iminophosphorano)methanide ligands in 6 are bound to
yttrium in a tridentate pseudoboat conformation with typical
metrical parameters.14,20,29 Two dithiocarbonimidate ligands
bridge the two seven-coordinate yttrium centers of 6, with each
{ButNCS2}2− unit in a mutually trans arrangement coordinating
by one N-donor to one yttrium center and one S-donor to the
other yttrium, with the final S-donor bridging the two metal
centers. These contacts form a Y2C2N2S4 open cage structure
formally made up of two YNCS and two YSCS four-membered
rings that are alternately above and below the Y(1)−S(1)−
Y(1A)−S(1A) plane. As would be expected, the terminal
Y(1)−S(1) distance (2.7489(7) Å) is much shorter than the
bridging Y(1)−S(2) value (2.9011(7) Å). The C−S (1.757(3)
Å mean) and CN distances (1.304(3) Å) observed in 6 are
indicative of single- and double-bond character in these respec-
tive bonds, as is the case for other dithiocarbonimidate com-
plexes such as [Pd(PMe3)2{C(S)2NPh-κ2-S1,3}] (C−S = 1.760(3)
Å mean; CN = 1.261(4) Å).32h It is notable that the C(32)−
N(3)−C(33) angle of 6 (122.2(2)°) is not markedly different
from that found for [Pd(PMe3)2{C(S)2NPh-κ2S1,3}] (C−N−C =
123.1(3)°)32h despite its coordination to yttrium, and the Y(1)−
N(3A) distance (2.482(2) Å) is slightly longer than the imino-
phosphorano Y−N distances (2.393(2)−2.455(2) Å).
isocyanate into the Y−Calkyl bond occurs. Deprotonation of the
tert-butyl group is then effected by the methanediide, forming a
methanide and a dianionic thioamidate and eliminating iso-
butylene. In support of this, C−H activation reactions mediated
by the related complexes [Y(BIPM)(CH2SiMe3)(THF)] and
[Y(BIPM)(I)(THF)2] have been observed previously.20 The
sulfur of the thioamidate then nucleophilically attacks the elec-
trophilic carbon of a second molecule of tert-butyl isocyanate to
form a C−S bond. This then rearranges to form the dithio-
carbonimidate, which subsequently dimerizes with concomitant
elimination of benzyl nitrile, which appears to react with other
species in the reaction mixture such as 134 to form an intrac-
table mixture of products that could not be conclusively
identified by mass spectrometry methods.
The NMR spectra of 6 were recorded in d8-THF due to the
low solubility of 6 in arene solvents, but the coordination of
d8-THF to the yttrium centers of 6 results in an equilibrium
mixture of complexes, presumably consisting of monomers and
dimers, which results in complex NMR spectra that do not vary
greatly with temperature. The 31P NMR spectrum of 6 exhibits
Addition of 2,6-diisopropylaniline to 1 quantitatively afforded
[Y(BIPM)(NHDipp)(THF)] (7) with the elimination of toluene,
as evidenced by 31P{1H} NMR spectroscopy, but in a poor
crystalline yield (13%) following workup (Scheme 1). Thus, the
Figure 5. Molecular structure of 6·3.5C7H8 with selective atom labeling. Displacement ellipsoids are set at the 40% probability level, and hydrogen atoms
(except methanide hydrogens) and lattice solvent are omitted for clarity. Symmetry operation to generate complete molecule: −3 + x, −y + 1, −z +1.
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Figure 6. Molecular structure of 7 with selective atom labeling. Displacement ellipsoids are set at the 40% probability level, and hydrogen atoms
(except amide hydrogen) are omitted for clarity.
Y−Calkyl bond in 1 reacts in preference in this instance to 1,2-
addition (hydroamination) across the YC bond, as was
observed for [Hf(BIPMH)(NHC6H4Me-4)(Cl)2], which was
formed from a 1,2-addition reaction between p-tolylamine and
[Hf(BIPM)(Cl)2].27 The spectroscopic data of 7 confirm the
retention of the methanediide, with the resonance in the 31P{1H}
NC(Me)CH(C5H3N-1,SiMe2CH2-2)-κ3-C,N,N′}(NHDipp)-
(THF)] (Y−N = 2.197(5) Å; Y−N−C = 154.9(4)°).36
The reaction between benzylpotassium (PhCH2K) and 1
results in a formal 1,2-carbopotassiation across the YCcarbene
bond to yield the yttriate polymer [Y(BIPM)(μ-η1:η6-CH2Ph)-
(μ-η1:η2-CH2Ph)K]∞ (8) (Scheme 1). As with other complexes
reported here, the crystalline yield of 8 was low (29%), even
though it is the only detectable product in the 31P NMR
spectrum of the reaction mixture. It is noteworthy that
[Y(BIPM)(CH2SiMe3)(THF)] reacts with PhCH2K to form
8 by ligand scrambling, and we therefore conclude that 8 is the
thermodynamic product, since it is stabilized by electrostatic
interactions between potassium and π-basic aryl substituents
(see below) and the polymer precipitates, driving the reaction
to completion. Group 3 and lanthanide organometallic com-
plexes commonly occlude salts within their coordination sphere
due to their high Lewis acidity, and mixed-metal aggregates are
commonplace.37 In the majority of cases, these complexes
occlude lithium halides, aryloxides, and alkyls and examples of
potassium alkyl occlusion are rare, but the aryl substituents in 8
provide an ideal environment for the coordination of potassium
cations, as is the case for related polymeric lanthanide heavier
alkali metal chains.38 Although 8 displays adequate solubility in
arene solvents, it rapidly crystallizes once seeded; hence, the
NMR spectroscopy was performed on d8-THF solutions of 8.
The NMR spectra of 8 are more straightforward than would be
expected from the solid-state structure (see below); therefore,
we propose that THF coordinates to yttrium and/or potassium
and breaks up the polymeric chain in solution into discrete
units. Both methylene signals of the benzyl groups of 8 there-
fore resonate at the same chemical shift (1H, δ 1.81 ppm (d,
2JYH = 6.0 Hz); 13C, δ 51.31 ppm (br, s)), and only one resonance
is observed in the 31P NMR spectrum (δ 1.42 ppm (d, 2JYP = 11.3
Hz)). The methanediide signal in the 13C{1H} NMR of 8 (δ
57.46 ppm (dt, JPC = 179.1 Hz, JYC = 3.0 Hz)) is slightly upfield
2
NMR spectrum (δ 5.48 (d, JYP = 13.0 Hz)) exhibiting a chem-
ical shift and coupling constant that is typical for yttrium bis-
(iminophosphorano)methanediide complexes.13,15,16 The anilide
1
proton was observed in the H NMR spectrum of 7 at δ 4.85
ppm, which is comparable to the value reported for the related
complex [Y{(C6H3Pri2-2,6)NC(Me)CH(C5H3N-1,SiMe2CH2-2)-
κ3-C,N,N′}(NHDipp)(THF)] (δ 4.75 ppm), which was also
prepared by an alkane elimination reaction.36 The potentially
diagnostic signal arising from the methanediide carbon could not
be observed in the 13C{1H} NMR spectrum of 7 even after long
accumulations on highly concentrated samples. However, the
anilide ipso carbon was readily observed (δ 152.32 ppm (d, 2JYC
=
3.0 Hz)), and this resonance compares very well to the value
reported for [Y{(C6H3Pri2-2,6)NC(Me)CH(C5H3N-1,Si-
Me2CH2-2)-κ3C,N,N′}(NHDipp)(THF)] (δ 151.8 ppm).36
The methanediide formulation of 7 was confirmed by X-ray
crystallography (depicted in Figure 6, with selected bond lengths
and angles given in Table 1) by its short Y(1)−C(1) distance
(2.453(2) Å) and P(1)−C(1)−P(2) angle (140.45(14)°), which
are more comparable to those found for 1 (YC = 2.357(3) Å;
P−C−P = 147.6(2)°)16 than for related yttrium bis-
(iminophosphorano)methanide complexes, which exhibit
longer Y−C distances and possess P−C−P angles that deviate
further from linearity.14,20,29 The BIPM framework of 7 adopts a
boat conformation, and the five-coordinate yttrium center is
additionally bound by the anilide and THF. The nonlinear Y(1)−
N(3)−C(32) angle (145.43(17)°) and the Y(1)−N(3) distance
(2.2519(19) Å) of 7 are in accord with the corresponding metrical
parameters observed for the related complex [Y{(C6H3Pri2-2,6)-
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Figure 7. Molecular structure of the monomer with selective atom labeling (a) and part of the polymeric chain (b) of 8·2C7H8. Displacement
ellipsoids are set at the 40% probabilitly level, and hydrogen atoms and lattice solvent are omitted for clarity.
of, and exhibits smaller coupling constants than, the resonance
observed for 1 (δ 61.81 ppm (dt, JPC = 207.3 Hz, JYC = 5.0 Hz)).
The solid-state structure of 8·2C7H8 was determined by
X-ray crystallography, and the monomer (a) and part of the
polymeric chain (b) are depicted in Figure 7, with selected
bond lengths and angles deposited in Table 1. The bond lengths
and angles within the BIPM scaffold of 8 are not markedly
different from those found in 1, although the Y(1)−C(1) distance
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1
and distilled before use. H, 13C, 29Si, and 31P NMR spectra were
recorded on a Bruker 400 spectrometer operating at 400.2, 100.6, 79.5,
and 162.0 MHz, respectively; chemical shifts are quoted in ppm and
are relative to TMS (1H, 13C, and 29Si) and external 85% H3PO4 (31P).
FTIR spectra were recorded on a Bruker Tensor 27 spectrometer.
Elemental microanalyses were carried out by Mr. Stephen Boyer at the
Microanalysis Service, London Metropolitan University, U.K., or by
Dr. Tong Liu at the University of Nottingham.
of 8 (2.453(2) Å) is longer than that observed in 1 (2.357(3) Å),16
most likely due to an additional interaction of the carbene
with potassium (K(1)···C(1) = 2.953(2) Å). This K···Ccarbene
distance is similar to that observed for [K2C(PPh2NPh)2]2
(K···Cmethanediide = 2.910(3) Å)39 but is much shorter than
K···Cmethanediide distances reported for other related potassium
bis(iminophosphorano)methanediide complexes.40 The five-
coordinate yttrium center of 8 is additionally bound by two
benzyl ligands (Y(1)−C(32) = 2.443(3) Å; Y(1)−C(39) =
2.467(3) Å), but no ipso-C-Ph contacts are evident; again, these
are longer than that observed for 1 (2.406(4) Å), which in con-
trast exhibits a Y−Cipso interaction (2.921(4) Å).16 The potassium
center of 8 exhibits a contact with C(1) and multihapto
interactions with a benzyl group and two P-phenyl groups of one
monomeric unit and with a neighboring benzyl group to form the
polymeric chain. These multihapto interactions can be assigned
nominally as η6 (range K(1)−{C(33)−C(38)} = 3.109(3)−
3.422(3) Å), η3 or η6 (range K(1)−C(2),C(3),C(7) = 3.118(2)−
3.289(2) Å; range K(1)−C(4),C(5),C(6) = 3.521(2)−3.672(2) Å),
η1 (K(1)−C(28) = 3.353(3) Å), and η2 (K(1A)−C(43) =
3.140(3) Å; K(1A)−C(44) = 3.122(3) Å) by comparison with
values observed for related complexes.38−40 Both η6 interactions
are asymmetric, and one may perhaps be more accurately assigned
as η3, because there is a difference of over 0.2 Å between the two
ranges.
Preparation of [Y(BIPM){NC(But)(CH2Ph)}(THF)] (2). A solution
of ButCN (0.17 g, 2.00 mmol) in toluene (10 mL) was added
dropwise to a precooled (−78 °C) solution of 1 (1.62 g, 2.00 mmol)
in toluene (10 mL). The light brown mixture was slowly warmed
to room temperature with stirring over 18 h. Volatiles were removed
in vacuo, and the resulting light brown oil was extracted with toluene
(2 mL) and stored at ambient temperature overnight to afford 2 as
colorless crystals. Yield: 0.24 g, 14%. Anal. Calcd for C47H62N3OP2Si2Y: C,
63.35; H, 6.91; N, 4.72. Found: C, 63.30; H, 6.91; N, 4.67. 1H NMR (d6-
benzene, 298 K): δ 0.10 (s, 18H, Si(CH3)3), 1.48 (m, 4H, OCH2CH2),
1.55 (s, 9H, C(CH3)3), 3.76 (m, 4H, OCH2CH2), 3.88 (s, 2H, CH2Ph),
7.16 (m, 13H, m- and p-Ph-CH and p-Bn-CH), 7.30 (vt, 3JHH = 7.6 Hz,
2H, m-Bn-CH), 7.35 (t, 3JHH = 6.8 Hz, 2H, o-Bn-CH), 7.89 (br, 8H, o-Ph-
CH). 13C{1H} NMR (d6-benzene, 298 K): δ 3.47 (Si(CH3)3), 25.00
(OCH2CH2), 29.13 (C(CH3)3), 43.02 (CH2Ph), 43.86 (C(CH3)3), 51.36
(dt, JPC = 152.0 Hz, JYC = 5.0 Hz, CP2), 70.77 (OCH2CH2), 124.75 (p-Bn-
CH), 127.29 (t, 2JPC = 5.5 Hz, o-Ph-CH), 128.65 (m-Bn-CH), 130.42 (o-
3
Bn-CH), 131.17 (t, JPC = 5.5 Hz, m-Ph-CH), 140.95 (br, ipso-Ph-C),
142.09 (ipso-Bn-C), 175.27 (d, 2JYC = 8.1 Hz, PhCH2C(But)N). 31P{1H}
NMR (d6-benzene, 298 K): δ 3.60 (d, JYP = 13.0 Hz, CP2). 29Si{1H}
2
NMR (d6-benzene, 298 K): δ −10.35 (NSi(CH3)3. FTIR ν/cm−1 (Nujol):
1671 (s, CN stretch), 1600 (w), 1282 (s), 1243 (s), 1105 (s), 1077 (s),
1051 (s), 979 (w), 835 (s), 757 (m), 738 (m), 713 (m), 695 (m), 677
(m), 646 (w), 608 (m), 541 (m), 521 (m).
SUMMARY AND CONCLUSIONS
■
A wide-ranging reactivity study of the yttrium alkyl carbene
complex [Y(BIPM)(CH2Ph)(THF)] (1) has been performed.
The reactions of 1 with alkyl nitriles and azides afforded [Y-
(BIPM){NC(But)(CH2Ph)}(THF)] (2) and [Y(BIPM){N3Ad-1,
Bn-3-κ2N1,3}(THF)] (3) by 1,2-migratory insertion reactions into
the Y−Calkyl bond, while the reactions of 1 with alkyl carbodiimides
and isocyanates yielded [Y{C(PPh2NSiMe3)2[C(NCy)2]-
κ4C,N,N′,N″}{C(NCy)2(CH2Ph)-κ2N,N′}] (4) and [Y{C-
(PPh2NSiMe3)2[C(O)(NBut)]-κ4C,N,N′,O}{C(O)(NBut)-
(CH2Ph)-κ2N,O}] (5) by additional [2 + 2]-cycloaddition reac-
tions, following classical reactivity patterns. The synthesis of
[Y(BIPM)(NHDipp)(THF)] (7) from 1 and 2,6-diisopropy-
laniline by alkane elimination is also in accord with examples
from the literature. In contrast, the treatment of 1 with an alkyl
isothiocyanate afforded dimeric [Y(BIPMH){C(S)2(NBut)-1-
κS,2-κN:μ,κS′}]2 (6) via a proposed deprotonation and reduc-
tive disproportionation, which is a novel reactivity profile for
early-metal carbene complexes with isothiocyanates. Finally, the
addition of benzylpotassium across the YCcarbene bond of 1 to
produce [Y(BIPM)(μ-η1:η6CH2Ph)(μ-η2:η2-CH2Ph)K]∞ (8) repre-
sents another reactivity mode for early-metal carbenes. The re-
sults reported herein represent further examples of unexpected
and unusual reactivities derived from highly polarized MC
double bonds that merit further investigation.
Preparation of [Y(BIPM){N3Ad-1,Bn-3-κ2N1,3}(THF)] (3). A solu-
tion of AdN3 (0.18 g, 1.00 mmol) in toluene (10 mL) was added
dropwise to a solution of 1 (0.81 g, 1.00 mmol) at −78 °C. The
orange mixture was slowly warmed to room temperature with stirring
over 24 h. Volatiles were removed in vacuo, and the resulting yellow
oil was extracted with toluene (3 mL) to afford colorless crystals of 3
at −30 °C. Yield: 0.27 g, 27%. Anal. Calcd for C52H68N5OP2Si2Y: C,
1
63.27; H, 6.94; N, 7.09. Found: C, 63.22; H, 6.86; N, 7.01. H NMR
(d6-benzene, 298 K): δ 0.13 (s, 18H, SiC(CH3)3), 1.31 (m, 4H,
OCH2CH2), 1.83 (br m, 6H, Ad-CH2), 2.22 (br m, 3H, Ad-CH), 2.29
(br m, 6H, Ad-CH2), 3.74 (m, 4H, OCH2CH2), 4.93 (s, 2H, CH2Ph),
6.92 (m, 3JHH = 6.8 Hz, 4H, m-Ph-CH), 6.98 (m, 2H, p-Ph-CH), 7.13
(m, 7H, m- and p-Ph-CH and p-Bn-CH), 7.20 (vt, 3JHH = 7.6 Hz, 2H,
3
m-Bn-CH), 7.39 (d, JHH = 7.6 Hz, 2H, o-Bn-CH), 7.45 (br m, 4H,
o-Ph-CH), 7.96 (br m, 4H, o-Ph-CH). 13C{1H} NMR (d6-benzene,
298 K): δ 3.96 (Si(CH3)3), 24.75 (OCH2CH2), 30.24 (Ad-CH), 37.15
2
(Ad-CH2), 44.89 (Ad-CH2), 56.83 (d, JYC = 3.0 Hz, NC-Ad), 59.81
(dt, JPC = 185.1 Hz, JYC = 4.0 Hz, CP2), 61.42 (CH2Ph), 70.60
(OCH2CH2), 126.65 (p-Bn-CH), 127.01 (vt, 2JPC = 6.6 Hz, o-Ph-CH),
2
127.22 (vt, JPC = 6.6 Hz, o-Ph-CH), 128.18 (p-Ph-CH), 128.44
(m-Bn-CH), 128.72 (p-Ph-CH), 129.08 (o-Bn-CH), 131.01 (vt, 3JPC
=
=
5.9 Hz, m-Ph-CH), 131.56 (vt, 3JPC = 5.9 Hz, m-Ph-CH), 140.83 (vt, JPC
52.0 Hz, ipso-Ph-C), 142.19 (ipso-Bn-C), 142.38 (vt, JPC = 45.4 Hz,
ipso-Ph-C). 31P{1H} NMR (d6-benzene, 298 K): δ 3.89 (d, 2JYP = 11.3
Hz, CP2). 29Si{1H} NMR (d6-benzene, 298 K): δ −10.60 (Si(CH3)3).
FTIR ν/cm−1 (Nujol): 1589 (w), 1434 (m), 1243 (s), 1164 (w), 1106
(s), 1072 (s), 1062 (s), 1044 (s), 830 (s), 769 (m), 754 (m), 745 (m),
733 (m), 714 (m), 699 (m), 677 (s), 660 (m), 652 (m), 608 (m), 571
(m), 543 (m), 521 (m), 511 (m).
EXPERIMENTAL SECTION
■
General Considerations. All manipulations were carried out using
standard Schlenk techniques or an MBraun UniLab glovebox, under an
atmosphere of dry nitrogen. Solvents were dried by passage through
activated alumina towers and degassed before use. All solvents were
stored over potassium mirrors (with the exception of THF, which was
stored over activated 4 Å molecular sieves). Deuterated solvents were
distilled from potassium, degassed by three freeze−pump−thaw cycles,
and stored under nitrogen. 1,16 1-adamantyl azide,41 and benzylpo-
tassium42 were prepared according to published procedures. All other
chemicals were purchased; all solid reagents were dried under vacuum
for 3 h, and all liquid reagents were dried over 4 Å molecular sieves
Preparation of [Y{C(PPh2NSiMe3)2[C(NCy)2]-κ4C,N,N′,N″}{C-
(NCy)2(CH2Ph)-κ2N,N′}] (4). Toluene (20 mL) was added to a
precooled (−78 °C) mixture of 1 (1.62 g, 2.00 mmol) and C(NCy)2
(0.83 g, 4.00 mmol). The yellow mixture was slowly warmed to room
temperature with stirring over 18 h. Volatiles were removed in vacuo,
and the resulting yellow oil was extracted with diethyl ether (2 mL) and
stored at ambient temperature overnight to afford 4 as colorless crystals.
Yield: 1.14 g, 47%. Anal. Calcd for C64H89N6P2Si2Y: C, 66.87; H, 7.80; N,
7.31. Found: C, 66.79; H, 7.73; N, 7.25. 1H NMR (d6-benzene, 298 K):
1260
dx.doi.org/10.1021/om3010178 | Organometallics 2013, 32, 1251−1264

Organometallics
Article
δ 0.11 (s, 18H, NSi(CH3)3), 0.39 (m, 2H, CH-2ax NCy), 0.83 (m, 2H,
CH-2ax NCy), 0.96 (m, 2H, CH-2ax NCy), 1.19−1.31 (m, 6H, CHax
NCy), 1.36 (m, 4H, CHax NCy), 1.61 (m, 4H, CHax NCy), 1.78 (m,
6H, CHeq NCy), 1.88 (m, 4H, CHeq NCy), 2.06 (m, 4H, CHeq NCy),
2.18 (m, 2H, CHeq NCy), 2.65 (m, 4H, CH-2eq NCy), 3.29 (m, 2H,
CH-1ax NCy), 3.52 (m, 1H, CH-1ax NCy), 3.85 (s, 2H, CH2Ph), 4.27
(m, 1H, CH-1ax NCy), 6.80 (vt, 3JHH = 7.6 Hz, 4H, m-Ph-CH), 6.88 (vt,
Si(CH3)3), 1.23, 1.38, 1.41 (s, 18H, C(CH3)3), 6.98 (vt, 3JHH = 7.6 Hz,
4H, Ph-CH), 7.14 (m, 8H, Ph-CH), 7.26 (m, 8H, Ph-CH), 7.29−7.51
(br m, 10H, Ph-CH), 7.68 (br m, 2H, Ph-CH), 8.00 (br m, 8H, Ph-
CH), HCP2 not observed. 13C{1H} NMR (d8-THF, 298 K): δ 2.32,
2.56 (Si(CH3)3), 14.90 (t, JPC = 106.6 Hz, HCP2), 27.57, 27.92, 28.40
(C(CH3)3), 56.27, 56.40, 56.45 (C(CH3)3), 125.51 (d, 2JPC = 13.8 Hz,
2
o-Ph-CH), 125.87 (d, JPC = 12.3 Hz, o-Ph-CH), 128.05, 128.11,
3
3
3JHH = 7.2 Hz, 2H, p-Ph-CH), 7.02 (vt, JHH = 7.2 Hz, 2H, p-Ph-CH),
128.30, 128.84 (p-Ph-CH), 129.47 (vt, JPC = 6.1 Hz, m-Ph-CH),
3
3
130.10 (vt, JPC = 5.4 Hz, m-Ph-CH), 134.25, 135.26 (ipso-Ph-C), NCS2
not observed. 31P{1H} NMR (d8-THF, 298 K): δ 18.56 (br, HCP2),
18.95 (dd, 2JPP = 12.2 Hz, 2JYP = 6.7 Hz, HCP2), 21.04 (dd, 2JPP = 12.2
Hz, 2JYP = 6.7 Hz, HCP2). 29Si{1H} NMR (d8-THF, 298 K): δ −6.00,
−4.69, −3.66 (Si(CH3)3). FTIR ν/cm−1 (Nujol): 1590 (br, w), 1417
(m), 1244 (m), 1164 (m), 1113 (s), 1082 (s), 1055 (s), 958 (m), 835
(s), 767 (m), 739 (m), 721 (m), 691 (m), 662 (w), 607 (w), 545 (w),
515 (w).
7.09 (m, JHH = 7.2 Hz, 4H, m-Ph-CH), 7.11 (t, JHH = 8.0 Hz, 1H,
p-Bn-CH), 7.25 (vt, 3JHH = 8.0 Hz, 2H, m-Bn-CH), 7.42 (d, 2H, 3JHH
=
3
3
7.6 Hz, o-Bn-CH), 7.67 (dd, JPH = 12.4 Hz, JHH = 6.8 Hz, 4H, o-Ph-
CH), 8.05 (dd, 3JPH = 12.0 Hz, 3JHH = 7.2 Hz, 4H, o-Ph-CH). 13C{1H}
NMR (d6-benzene, 298 K): δ 3.77 (NSi(CH3)3), 23.75 (dt, JPC = 106.6
Hz, JYC = 3.1 Hz, CP2), 25.96 (C-4 NCy), 26.23 (C-4 NCy), 26.89 (C-3
NCy), 27.21 (C-3 NCy), 27.30 (C-3 NCy), 27.75 (C-2 NCy), 32.75 (C-
2 NCy), 34.66 (C-2 NCy), 34.82 (CH2Ph), 36.14 (C-2 NCy), 57.29 (C-
1 NCy), 57.37 (C-1 NCy), 57.80 (C-1 NCy), 126.27 (p-Bn-CH),
Preparation of [Y(BIPM)(NHDipp)(THF)] (7). A solution of
DippNH2 (0.72 g, 4.00 mmol) in toluene (10 mL) was added drop-
wise to a solution of 1 (3.24 g, 4.00 mmol) in toluene (10 mL) at
−78 °C. The yellow mixture was slowly warmed to room temperature
with stirring over 72 h. Volatiles were removed in vacuo, and the
resulting yellow oil was washed with pentane (20 mL) to afford anal-
ytically pure 7. Yield: 2.13 g, 60%. A small portion was recrystallized
from toluene (0.45 g, 13%). Anal. Calcd for C47H62N3OP2Si2Y: C,
2
2
127.31 (vt, JPC = 6.0 Hz, o-Ph-CH), 127.46 (vt, JPC = 6.0 Hz, o-Ph-
CH), 127.69 (m-Bn-CH), 128.60 (o-Bn-CH), 130.49 (p-Ph-CH),
3
130.61 (p-Ph-CH), 130.63 (dd, JPC = 118.8 Hz, JPC = 23.1 Hz, ipso-
Ph-C), 133.06 (vt, 3JPC = 5.0 Hz, m-Ph-CH), 134.00 (vt, 3JPC = 5.0 Hz,
m-Ph-CH), 136.58 (d, JPC = 14.1 Hz, ipso-Ph-C), 137.18 (ipso-Ph-C),
137.79 (dd, JPC = 68.4 Hz, 3JPC = 14.0 Hz, ipso-Ph-C), 138.47 (ipso-Bn-
C), 153.30 (CN2), 175.98 (d, JYC = 2.0 Hz, PhCH2CN2). 31P{1H}
2
1
NMR (d6-benzene, 298 K): δ 17.96 (d, JYP = 4.4 Hz, CP2). 29Si{1H}
2
63.28; H, 7.01; N, 4.71. Found: C, 63.39; H, 7.12; N, 4.88. H NMR
NMR (d6-benzene, 298 K): δ −5.87 (Si(CH3)3). FTIR ν/cm−1 (Nujol):
1526 (s), 1246 (s), 1221 (s), 1191 (m), 1171 (m), 1110 (s), 1074 (s),
1029 (s), 996 (m), 932 (m), 890 (m), 834 (s), 741 (s), 709 (s), 695 (s),
660 (m), 608 (m), 557 (m), 535 (m).
(d6-benzene, 298 K): δ 0.02 (s, 18H, Si(CH3)3), 1.40 (m, 4H, OCH2CH2),
1.61 (d, 3JHH = 6.8 Hz, 12H, CH(CH3)2), 3.31 (sept, 3JHH = 6.8 Hz, 2H,
CH(CH3)2), 4.02 (m, 4H, OCH2CH2), 4.85 (s, 1H, NH), 6.89 (t, 3JHH
7.6 Hz, 1H, p-Dipp-CH), 7.02 (br, 12H, m- and p-Ph-CH), 7.24 (t, 3JHH
=
=
7.6 Hz, 2H, m-Dipp-CH), 7.71 (br, 8H o-Ph-CH). 13C{1H} NMR (d6-
benzene, 298 K): δ 3.49 (Si(CH3)3), 22.91 (CH(CH3)2), 24.72
(OCH2CH2), 30.47 (CH(CH3)2), 70.47 (OCH2CH2), 114.46 (p-
Dipp-CH), 122.41 (m-Dipp-CH), 127.06 (t, 3JPC = 61.3 Hz, m-PhCH),
128.72 (br, p-PhCH), 131.05 (br, o-PhCH), 131.69 (o-Dipp-C),
Preparation of [Y{C(PPh2NSiMe3)2[C(O)(NBut)]-κ4C,N,N′,O}{C-
(O)(NBut)(CH2Ph)-κ2N,O}] (5). A solution of ButNCO (0.44 g, 4.00
mmol) in toluene (10 mL) was added dropwise to a solution of 1
(1.62 g, 2.00 mmol) in toluene (10 mL) at −78 °C. The brown
mixture was slowly warmed to room temperature with stirring over 18
h. Volatiles were removed in vacuo, and the resulting brown oil was
extracted with toluene (2 mL) and stored at ambient temperature
overnight to afford 5 as colorless crystals. Yield: 0.38 g, 19%. Anal.
Calcd for C52H71N4O3P2Si2Y: C, 62.01; H, 7.11; N, 5.57. Found: C,
61.88; H, 6.96; N, 5.58. 1H NMR (d6-benzene, 298 K): δ 0.29 (s, 18H,
Si(CH3)3), 0.95 (s, 9H, C(CH3)3), 1.36 (m, 4H, OCH2CH2), 1.46 (s,
9H, C(CH3)3), 3.60 (m, 4H, OCH2CH2), 3.64 (s, 2H, CH2Ph), 6.66
2
152.32 (d, JYC = 3.0 Hz, ipso-Dipp-C), ipso-Ph-C and CP2 not
2
observed. 31P{1H} NMR (d6-benzene, 298 K): δ 5.48 (d, JYP = 13.0
Hz CP2). 29Si{1H} NMR (d6-benzene, 298 K): δ −9.04 (Si(CH3)3).
FTIR ν/cm−1 (Nujol): 3062 (m, N−H stretch), 1590 (m), 1424 (s),
1333 (m), 1300 (m), 1106 (s), 1055 (s), 764 (m), 744 (m), 712 (m),
696 (m), 649 (w), 610 (m), 602 (m), 547 (m), 510 (m).
Preparation of [Y(BIPM)(μ-η1:η6-CH2Ph)(μ-η1:η2-CH2Ph)K]∞
(8). THF (30 mL) was added to a precooled (−78 °C) mixture of
1 (2.43 g, 3.00 mmol) and PhCH2K (0.39 g, 3.00 mmol). The brown
mixture was slowly warmed to room temperature with stirring over 18
h. Volatiles were removed in vacuo, and the resulting brown oil was
recrystallized from hot toluene (5 mL) to afford 8 as yellow crystals.
Yield: 0.76 g, 29%. Anal. Calcd for C45H52KN2P2Si2Y: C, 62.34; H,
3
3
(vt, JHH = 7.2 Hz, 4H, m-Ph-CH), 6.71 (t, JHH = 7.2 Hz, 2H, p-Ph-
3
3
CH), 7.13 (m, JHH = 7.2 Hz, 3H, m- and p-Bn-CH), 7.23 (t, JHH
7.2 Hz, 4H, m-Ph-CH), 7.27 (m, 2H, p-Ph-CH), 7.41 (d, JHH = 7.2
=
3
3
Hz, 1H, o-Bn-CH), 7.57 (d, JHH = 6.8 Hz, 1H, o-Bn-CH), 7.70 (dd,
3JPH = 12.8 Hz, 3JHH = 6.8 Hz, 4H, o-Ph-CH), 8.26 (dd, 3JPH = 12.4 Hz,
3JHH = 6.8 Hz, 4H, o-Ph-CH). 13C{1H} NMR (d6-benzene, 298 K): δ
3.57 (Si(CH3)3), 25.33 (OCH2CH2), 28.80 (C(CH3)3), 29.31 (dt,
1
6.05; N, 3.23. Found: C, 62.22; H, 5.97; N, 3.16. H NMR (d8-THF,
2
JPC = 108.1 Hz, JYC = 2.3 Hz, CP2), 29.89 (C(CH3)3), 41.99 (d, 3JYC
=
298 K): δ −0.19 (s, 18H, Si(CH3)3), 1.81 (d, JYH = 6.0 Hz, 4H,
3
3
CH2Ph), 6.34 (t, JHH = 6.4 Hz, 2H, p-Bn-CH), 6.80 (m, JHH = 8.0
3.0 Hz, CH2Ph), 51.38 (C(CH3)3), 52.13 (C(CH3)3), 69.28
3
2
Hz, 8H, m-Ph-CH), 6.99 (m, JHH = 7.2 Hz, 6H, m- and o-Bn-CH),
(OCH2CH2), 126.28 (p-Bn-CH), 126.67 (t, JPC = 6.0 Hz, o-Ph-
7.07 (t, 3JHH = 7.2 Hz, 4H, p-Ph-CH), 7.15 (t, 3JHH = 7.2 Hz, 1H, o-Bn-
CH), 7.23 (t, 3JHH = 7.2 Hz, 1H, o-Bn-CH), 7.39 (dd, 2JPH = 12.4 Hz,
3JHH = 6.6 Hz, 8H, o-Ph-CH). 13C{1H} NMR (d8-THF, 298 K): δ 3.15
(Si(CH3)3), 51.31 (br, CH2Ph), 57.46 (dt, JPC = 179.1 Hz, JYC = 3.0
Hz, CP2), 113.29 (p-Bn-CH), 122.35 (p-Bn-CH), 125.07 (m-Bn-CH),
126.36 (t, 2JPC = 6.0 Hz, o-Ph-CH), 127.02 (m-Bn-CH), 127.66 (p-Ph-
2
CH), 127.20 (t, JPC = 6.0 Hz, o-Ph-CH), 127.82 (m-Bn-CH), 129.75
3
(o-Bn-CH), 129.99 (p-Ph-CH), 130.20 (p-Ph-CH), 132.12 (t, JPC
=
5.0 Hz, m-Ph-CH), 133.27 (dd, JPC = 116.7 Hz, 3JPC = 5.0 Hz, ipso-Ph-
3
C), 134.60 (t, JPC = 5.0 Hz, m-Ph-CH), 135.25 (dd, JPC = 108.7 Hz,
3JPC = 16.1 Hz, ipso-Ph-C), 136.49 (ipso-Bn-C), 156.85 (t, JPC = 5.0
2
Hz, NCO), 179.13 (d, JYC = 2.0 Hz, PhCH2NCO). 31P{1H} NMR
2
3
(d6-benzene, 298 K): δ 20.57 (CP2). 29Si{1H} NMR (d6-benzene, 298
K): δ −5.78 (Si(CH3)3). FTIR ν/cm−1 (Nujol): 1592 (m), 1519 (m),
1294 (m), 1219 (m), 1170 (m), 1113 (s), 1069 (s), 1035 (s), 839 (s),
767 (m), 695 (m), 620 (m), 601 (m), 545 (m), 522 (m), 509 (m).
Preparation of [Y(BIPMH){C(S)2(NBut)-1-κS,2-κN:μ,κS′}]2 (6).
A solution of ButNCS (0.25 g, 2.20 mmol) in toluene (10 mL) was
added dropwise to a solution of 1 (1.62 g, 2.00 mmol) in toluene
(10 mL) at −78 °C. The orange mixture was slowly warmed to room
temperature with stirring over 24 h. The mixture was filtered to isolate
analytically pure 6 as a white solid. Yield: 0.52 g, 33%. X-ray-quality
crystals were grown from a hot toluene solution. Anal. Calcd for
C36H49N3P2S2Si2Y: C, 54.39; H, 6.21; N, 5.29. Found: C, 54.29; H,
6.27; N, 5.31. 1H NMR (d8-THF, 298 K): δ 0.11, 0.14 (s, 36H,
CH), 127.94 (o-Bn-CH), 128.71 (o-Bn-CH), 131.06 (t, JPC = 5.0 Hz,
m-Ph-CH), 141.27 (vt, JPC = 48.3 Hz, ipso-Ph-C), 154.49 (ipso-Bn-C).
2
31P{1H} NMR (d8-THF, 298 K): δ 1.42 (d, JYP = 11.3 Hz, CP2).
29Si{1H} NMR (d8-THF, 298 K): δ −12.39 (SiMe3). FTIR v/cm−1
(Nujol): 1586 (s), 1434 (m), 1246 (s), 1175 (m), 1106 (s), 1077 (s),
1051 (s), 830 (s), 772 (m), 754 (m), 739 (m), 728 (m), 717 (m), 698
(m), 645 (m), 609 (m), 539 (m), 512 (m).
X-ray Crystallography. Crystal data for compounds 2−8 are
given in Tables 2 and 3, and further details of the structure deter-
minations are in the Supporting Information. Bond lengths and angles
are given in Table 1. Crystals were examined variously on a Bruker
APEX CCD area detector diffractometer using graphite-monochro-
mated Mo Kα radiation (λ = 0.71073 Å) or on an Oxford Diffraction
1261
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Organometallics
Article
Table 2. Crystallographic Data for 2−5
2·C7H8
3
4·C4H10O
5
formula
C47H62N3OP2Si2Y·C7H8
984.16
C52H68N5OP2Si2Y
986.14
C64H89N6P2Si2Y·C4H10O
1223.56
C52H71N4O3P2Si2Y
1007.16
fw
cryst size, mm
0.24 × 0.38 × 0.62
triclinic
0.004 × 0.008 × 0.014
monoclinic
P21/c
0.22 × 0.25 × 0.45
triclinic
0.02 × 0.19 × 0.22
triclinic
cryst syst
space group
P1
P1
̅
P1
̅
̅
a, Å
10.5979(7)
12.8692(8)
20.1907(13)
82.257(2)
87.160(2)
80.411(2)
2689.5(3)
2
12.725(7)
14.098(2)
14.224(2)
19.349(3)
90.999(3)
90.104(3)
119.346(2)
3381.5(9)
2
11.5702(17)
13.0541(19)
18.880(3)
80.088(3)
88.140(3)
72.461(2)
2677.9(7)
2
b, Å
19.531(11)
20.748(11)
c, Å
α, deg
β, deg
101.224(10)
γ, deg
V, Å3
5058(5)
4
Z
ρcalcd, g cm−3
μ, mm−1
1.215
1.295
1.202
1.249
1.227
1.306
0.990
1.237
no. of rflns measd
no. of unique rflns, Rint
no. of rflns with F2 > 2σ(F2)
transmn coeff range
20010
36791
17477
15606
9460, 0.0173
8254
8932, 0.1079
5999
11229, 0.0381
9163
6986, 0.0718
4479
0.50−0.74
0.0415, 0.1067
0.0495, 0.1119
1.033
0.441−0.746
0.0708, 0.1771
0.1099, 0.2011
1.03
0.64−0.79
0.0665, 0.1710
0.0789, 0.1791
1.017
0.74−0.98
0.0946, 0.2388
0.1401, 0.2633
1.067
a
R, Rw (F2 > 2σ(F2))
a
R, Rw (all data)
a
S
no. of params
693
574
727
589
max, min diff map, e Å−3
1.145, −0.333
1.444, −1.132
2.078, −2.199
2.183, −0.877
a
Conventional R = ∑||Fo| − |Fc||/∑|Fo|; Rw = [∑w(Fo2 − Fc2)2/∑w(Fo )2]1/2; S = [∑w(Fo2 − Fc2)2/(no. of data) − (no. of params))]1/2 for all data.
2
Table 3. Crystallographic Data for 6−8
6·3.5C7H8
7
8·2C7H8
formula
C72H96N6P4S4Si4Y2·3.5C7H8
1910.32
C47H64N3OP2Si2Y
894.04
C45H52K N2P2Si2Y·2C7H8
1051.28
fw
cryst size, mm
0.07 × 0.07 × 0.18
monoclinic
P21/n
0.066 × 0.250 × 0.307
monoclinic
P21/n
0.113 × 0.288 × 0.372
monoclinic
P21/n
cryst syst
space group
a, Å
11.87174(19)
18.9361(3)
22.0918(4)
97.8907(15)
4919.31(14)
2
11.5102(3)
23.0440(5)
17.9369(5)
97.652(3)
4715.2(2)
4
20.2089(3)
11.4985(2)
23.9442(4)
92.0323(17)
5560.45(17)
4
b, Å
c, Å
β, deg
V, Å3
Z
ρcalcd, g cm−3
μ, mm−1
1.290
1.259
1.256
3.808
3.146
3.388
no. of rflns measd
no. of unique rflns, Rint
no. of rflns with F2 > 2σ(F2)
transmn coeff range
28086
21664
21940
8864, 0.0361
7206
9391, 0.040
8016
10928, 0.0341
9206
0.67−0.81
0.0356, 0.0928
0.0456, 0.0965
1.048
0.448−0.814
0.0348, 0.0820
0.0442, 0.0885
1.02
0.478−1.125
0.0387, 0.0897
0.0491, 0.0959
1.006
a
R, Rw (F2 > 2σ(F2))
a
R, Rw (all data)
a
S
no. of params
488
526
653
max, min diff map, e Å−3
0.429, −0.650
0.670, −0.480
0.786, −0.663
a
Conventional R = ∑||Fo| − |Fc||/∑|Fo|; Rw = [∑w(Fo2 − Fc2)2/∑w(Fo )2]1/2; S = [∑w(Fo2 − Fc2)2/(no. of data) − (no. of params))]1/2 for all data.
2
SuperNova Atlas CCD diffractometer using mirror-monochromated
Cu Kα radiation (λ = 1.5418 Å). Intensities were integrated from data
recorded on 0.3° (APEX) or 1° (SuperNova) frames by ω rotation.
Cell parameters were refined from the observed positions of all strong
reflections in each data set. Semiempirical absorption corrections
based on symmetry-equivalent and repeat reflections (APEX) or
Gaussian grid face-indexed absorption corrections with a beam profile
correction (Supernova) were applied. The structures were solved
variously by direct and heavy-atom methods and were refined by full-
matrix least squares on all unique F2 values, with anisotropic displace-
ment parameters for all non-hydrogen atoms and with constrained
riding hydrogen geometries; Uiso(H) was set at 1.2 (1.5 for methyl
groups) times the Ueq value of the parent atom. The largest features in
the final difference syntheses were close to heavy atoms and were of
no chemical significance. Highly disordered solvent molecules of
crystallization in 6·3.5C7H8 could not be modeled and were treated
1262
dx.doi.org/10.1021/om3010178 | Organometallics 2013, 32, 1251−1264

Organometallics
Article
with the Platon SQUEEZE procedure.43 Programs used were Bruker
AXS SMART44 and CrysAlisPro45 (control), Bruker AXS SAINT44
and CrysAlisPro45 (integration), and SHELXTL46 and OLEX247 (struc-
ture solution and refinement and molecular graphics).
(18) Wooles, A. J.; Cooper, O. J.; McMaster, J.; Lewis, W.; Blake, A.
J.; Liddle, S. T. Organometallics 2010, 29, 2315.
(19) (a) Cooper, O. J.; McMaster, J.; Lewis, W.; Blake, A. J.; Liddle,
S. T. Dalton Trans. 2010, 5074. (b) Cooper, O. J.; Mills, D. P.;
McMaster, J.; Moro, F.; Davies, E. S.; Lewis, W. L.; Blake, A. J.; Liddle,
S. T. Angew. Chem., Int. Ed. 2011, 50, 2383. (c) Mills, D. P.; Moro, F.;
McMaster, J.; Van Slageren, J.; Lewis, W. L.; Blake, A. J.; Liddle, S. T.
Nature Chem. 2011, 3, 454. (d) Mills, D. P.; Cooper, O. J.; Tuna, F.;
McInnes, E. J. L.; Davies, E. S.; McMaster, J.; Moro, F.; Lewis, W.;
Blake, A. J.; Liddle, S. T. J. Am. Chem. Soc. 2012, 134, 10047.
(20) Mills, D. P.; Soutar, L.; Lewis, W.; Blake, A. J.; Liddle, S. T. J.
Am. Chem. Soc. 2010, 132, 14379.
(21) Liddle, S. T.; Mills, D. P. Dalton Trans. 2009, 5592.
(22) (a) den Haan, K. H.; Luinstra, G. A.; Meetsma, A.; Teuben, J. H.
Organometallics 1987, 6, 1509. (b) Avent, A. G.; Caro, C. F.;
Hitchcock, P. B.; Lappert, M. F.; Li, Z.; Wei, X.-H. Dalton Trans. 2004,
1567. (c) Barroso, S.; Cui, J.; Carretas, J. M.; Cruz, A.; Santos, I. C.;
Duarte, M. T.; Telo, J. P.; Marques, N.; Martins, A. M. Organometallics
2009, 28, 3449. (d) Caseley, I. J.; Ziller, J. W.; Evans, W. J.
Organometallics 2011, 30, 4873.
ASSOCIATED CONTENT
* Supporting Information
CIF files giving crystallographic data for 2−8. This material is
available free of charge via the Internet at http://pubs.acs.org.
■
S
AUTHOR INFORMATION
Corresponding Author
*E-mail: stephen.liddle@nottingham.ac.uk.
■
Notes
The authors declare no competing financial interest.
ACKNOWLEDGMENTS
■
We thank the Royal Society for a University Research Fellowship
(S.T.L.), and the EPSRC, European Research Council, and the
University of Nottingham for generously supporting this work.
(23) Evans, W. J.; Walensky, J. R.; Ziller, J. W.; Rheingold, A. L.
Organometallics 2009, 28, 3350.
(24) Turner, Z. R.; Bellabarba, R.; Tooze, R. P.; Arnold, P. A. J. Am.
Chem. Soc. 2010, 132, 4050.
(25) Panda, T. K.; Trambitas, A. G.; Bannenberg, T.; Hrib, C. G.;
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