Insertion of tBuNC into thorium-phosphorus and thorium-arsenic bonds: Phosphaazaallene and arsaazaallene moieties in f element chemistry

Article abstract of DOI:10.1039/c6dt00776g

The reactivity of thorium-phosphido and thorium-arsenido bonds was probed using tert-butyl isocyanide, ^tBuNC. Reaction of (C₅Me₅)₂Th[E(H)R]₂, E = P, As; R = 2,4,6-ⁱPr₃C₆

Full text of DOI:10.1039/c6dt00776g

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Insertion of tBuNC into thorium–phosphorus and
thorium–arsenic bonds: phosphaazaallene and
arsaazaallene moieties in f element chemistry†
Cite this: DOI: 10.1039/c6dt00776g
Andrew C. Behrle and Justin R. Walensky*
Received 26th February 2016,
Accepted 13th April 2016
The reactivity of thorium–phosphido and thorium–arsenido bonds was probed using tert-butyl iso-
cyanide, tBuNC. Reaction of (C5Me5)2Th[E(H)R]2, E = P, As; R = 2,4,6-iPr3C6H2, 2,4,6-Me3C6H2 with tBuNC
affords the first phosphaazaallene and arsaazaallene moieties with an f-element.
DOI: 10.1039/c6dt00776g
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Introduction
Results and discussion
Hydroelementation reactions such as hydrophosphination1,2
are atom efficient processes which are important in developing
building blocks containing phosphorus. For example, tertiary
phosphines are of interest as ligands3–5 and for various
applications.6–8 However, the development of these reactions
in organoactinide chemistry9 has been attenuated by a lack of
starting materials.
Despite the intensity with which complexes with actinide–
nitrogen bonds have been studied,10–13 there exists a tremen-
dous knowledge gap with respect to the heavier pnictogen
elements. To date, twenty actinide–phosphido or phosphini-
dene bonds14–26 and five actinide–arsenido bonds27–29 have
been reported. Of these, only nine thorium–phosphorus and
one thorium–arsenic bond are known.
The synthesis of (C5Me5)2Th[P(H)Tipp]2, Tipp = 2,4,6-iPr3C6H2,
the first primary phosphido complex of thorium, was recently
described.26 In the same vein, we have begun investigating
the reactivity of primary phosphido and arsenido complexes.
In an effort to expand the scope of thorium–pnictogen
complexes, we synthesized (C5Me5)2Th[P(H)Mes]2, 1, Mes =
2,4,6-Me3C6H2, from the stoichiometric salt metathesis
reaction between (C5Me5)2ThCl2 and KP(H)Mes, eqn (1).
Complex 1 was isolated as a vibrant orange crystalline solid in
54% yield. The diagnostic spectroscopic features include the
doublet P–H resonance and the νPH stretch centered at
3.80 ppm with 1JP–H = 224 Hz and 2304 cm−1, respectively. The
1
large JP–H coupling constant reflects the large amount of
s-character in the P–H bond.
The 31P{1H} resonance is located at 15.37 ppm and
compares well to the 31P{1H} resonance of a structurally
similar thorium–phosphido compound, (C5Me5)2Th[P(H)Tipp]2,
located at 1.66 ppm. The molecular structure of 1 is shown
in Fig. 1 and mimics the bond distances and angles of
(C5Me5)2Th[P(H)Tipp]2.
Due to the dearth of actinide–phosphorus and actinide–
arsenic bonds, the reactivity of these bonds is unknown.
Migratory insertion, the initial step in many catalytic cycles,
has been used historically to probe reactivity. In transition
metals, primary phosphido complexes are also sparse,30–37
but Waterman’s group has investigated the reactivity of
t
zirconium–phosphorus bonds with BuNC.38 Interestingly, a
While actinide–phosphido complexes are few in number,
the number of structurally characterized actinide–arsenido
compounds is five: a bimetallic thorium poly-arsenide cluster,
proton migration from the phosphorus to the carbon of the
isocyanide occurs. Here we describe the synthesis of new
thorium phosphido and arsenido complexes and their re-
t
[Cp′2Th(µ–η2:1:2:1-As6)ThCp′2] (Cp′ = C5H3 Bu2),29 and a series
t
of uranium(IV) complexes: [{U(TrenTIPS)}2(μ–η2:η2-As2H2)],27
activity with BuNC, which differs from their transition metal
[U(TrenTIPS)(AsH2)], [U(TrenTIPS)(AsH)][K(B15C5)2], and
analogs.
[{U(TrenTIPS)(AsK2)}4] TrenTIPS
=
N(CH2CH2NSiPri3).28 We
hypothesized that the 2,4,6-iPr3C6H2 framework would be steri-
cally large enough to stabilize an actinide metal center such as
thorium. Using room temperature σ-bond metathesis between
(C5Me5)2ThMe2 and two equivalents of H2AsTipp, we success-
fully isolated the first organothorium primary arsenido
complex, (C5Me5)2Th[As(H)Tipp]2, 2, eqn (2):
Department of Chemistry, University of Missouri, Columbia, MO 65211, USA.
E-mail: walenskyj@missouri.edu
†Electronic supplementary information (ESI) available. CCDC 1455163–1455166,
1455345. For ESI and crystallographic data in CIF or other electronic format see
DOI: 10.1039/c6dt00776g
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ð1Þ
ð2Þ
Compound 2 was isolated as a ruby red crystalline solid in N(CH2CH2NSiMe3)33−),39 [U(TrenTIPS)(AsH2)]28 reported by
70% yield. The diagnostic spectroscopic handles include the Waterman and Liddle’s groups, respectively. The molecular
As–H resonance at δ 2.61 in the 1H NMR spectrum and the structure of 2 is shown in Fig. 2. The Th1–As1 bond length is
νAsH stretch at 2089 cm−1 in the IR spectrum. The IR stretching 3.0028(6) Å and is slightly longer than the sum of the single
frequencies compare well to the νAsH stretches at 2061 cm−1
and 2052 cm−1 for zirconium(IV) and uranium(IV) primary
arsenido complexes, [(N3N)ZrAsHR] (R = Mes and Ph; N3N =
Fig. 1 Thermal ellipsoid plot of 1 at the 50% probability level. Hydro-
gens have been omitted for clarity. Selected bond distances (Å) and
angles (°): Th1–P1, 2.872(5); P1–C11, 1.829(3); P1–Th–P1*, 102.68(2);
Th1–P1–C11, 128.45(9).
Fig. 2 Thermal ellipsoid plot of 2 at the 50% probability level. Hydro-
gens have been omitted for clarity. Selected bond distances (Å) and
angles (°): Th1–As1, 3.0028(6); As1–C11, 1.959(5); As1–Th1–As1*, 88.02
(2); Th1–As1–C11, 116.53(15).
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bond covalent radii for thorium and arsenic (2.96 Å).40 The phospha- and arsaazaallene complexes. As with transition
Th1–As1–C11 bond angle is 116.53(15)°. metals, such complexes are very rare as only two phosphaazaal-
We sought to investigate the reactivity of 1 and 2 through lene compounds have been isolated: (η1-Nacnac)Ti(CNtBu)(η2-
insertion reaction with CO surrogates. Waterman’s group has N,C)-tBuNCvPMes*)41 (Nacnac = [2,6-iPr2C6H3]NC(CH3)CHC
reported on the generation of phosphaalkenes and arsaalkenes (CH3)N[2,6-iPr2C6H3], Mes* = 2,4,6-tBu3C6H2) and Cp′2Nb(Cl)
from the reaction between a primary phosphido/arsenido organo- (η2-N,C)-PhNCvPMes*).42
metallic complex and an alkyl isocyanide.38,39 We anticipated
There is a substantial elongation of the N–C bond (N2–C11)
a
similar reactivity with our thorium complexes. When to 1.348(8) and 1.347(7) Å in 4 and 5, respectively, compared to
tert-butyl isocyanide was added to (C5Me5)2Th[P(H)Tipp]2 or 1 a metal free heterocumulene such as PhNvCvPMes*, with a
the solution underwent a color change to yellow, eqn (3). N–C bond distance of 1.210 Å.43 The N–C bonds in 4 and 5 are
Initial spectroscopic experiments showed that one equivalent also longer than those found in products of isocyanide inser-
of the primary phosphine had been formed in the reaction. tion into actinide–alkyl bonds. For example, 1.276(7) Å was
After recrystallization from a concentrated methylcyclohexane observed in (C5Me5)(C8H8)U[η2-(N,C)-C(Ph)vNtBu].44 Addition-
solution, the η2-(N,C)-phosphaazaallene thorium complexes ally the N–C–E bond angle is decreased to 152.1(5) and
[(C5Me5)2Th(CNtBu)(η2-N,C)-(tBuNCvPTipp)],
3,
[(C5Me5)2Th(CNtBu)(η2-N,C)-(tBuNCvPMes)], 4, were isolated 171.0° of PhNvCvPMes*. The CvP bond distance in 4 of
as yellow solids. 1.691(6) Å is only slightly longer than the CvP of 1.651(1) Å in
and 150.3(4)°, respectively, relative to the N–C–E bond angle of
ð3Þ
The diagnostic spectroscopic features associated with 3 and PhNvCvPMes* and matches the CvP bond length of 1.688(19)
4 include the stretches at 2181 and 2186 cm−1, and 1600 and
Å
in (C5H4SiMe3)2Nb(Cl)[η2-(N,C)-PhNCvP(2,4,6-tBu3C6H2)].
1602 cm−1, which can be assigned to the νCN and νCP stretches, The Th1–N2 bond distances of 2.346(5) and 2.364(4) Å in 4
respectively. The 31P NMR resonances shifted slightly upfield and 5, respectively, compare well to other thorium–amido
from the starting material to −21.28 and −10.70 ppm for bond lengths of 2.389(2) Å,
3 and 4, respectively. Additionally, the 13C NMR resonance of [η5-1,2,4-(Me3C)3C5H2]2Th(Cl)[N(p-tolyl)SiH2Ph];45 2.322(5) Å,
the central carbon of the phosphaazaallene was found at [η5-1,2,4-(Me3C)3C5H2]2Th[N(p-tolyl(Se–Se))];45 and 2.256(8) Å,
1
150.85 and 151.05 ppm with JP−C = 152.3 Hz and 103.0 Hz, (C5Me5)2Th[NC(Ph)(CH2Ph)]2.46
for 3 and 4, respectively. Compound 2 exhibited a similar
The formation of 4 and 5 is expected to occur through a 1,1
reactivity to yield a η2-(N,C)-arsaazaallene thorium complex insertion of the alkyl isocyanide in the Th–P bond. Unlike the
[(C5Me5)2Th(CNtBu)(η2-N,C)-(tBuNCvAsTipp)], 5, as an orange [(N3N)ZrEHR] (E = P, As; R = Cy, Ph) complexes which can
solid. The spectroscopic features of 5 can be found in undergo 1,2 rearrangement to phospha/arsa-azaalkenes, 4 and
Table 1.
5 do not undergo rearrangement, rather a double reduction of
The solid-state structures of 4 and 5 were determined using the alkyl isocyanide with the concomitant release of H2ER (E =
X-ray diffraction studies, Fig. 3. Table 2 lists selected bond dis- P, As; R = Tipp, Mes). There are two conceivable reaction path-
tances (Å) and angles (°). Compounds 4 and 5 are isostructural ways for the generation of 4 and 5, Fig. 4. The first involves a
with one another and represent the first examples of actinide transient terminal thorium–phosphinidene intermediate.
There is a literature precedent for this route as Mindiola’s
group have reported the reaction of a terminal titanium phos-
t
phinidene, (η1-Nacnac)Ti(CH2 Bu)(PMes*), with a tert-butyl iso-
Table 1 Spectroscopic features of compounds 3, 4, and 5
cyanide to yield the titanium phosphaazaallene complex, (η1-
Nacnac)Ti(CNtBu)(η2-N,C)-tBuNvCvPMes*).41 The other route
is 1,1 insertion of the isocyanide to form an η2-iminoacyl, fol-
lowed by an intramolecular deprotonation. To investigate the
possible reaction pathway, we attempted the addition of tert-
butyl isocyanide to (C5Me5)2Th[P(H)Tipp]2 at −200 °C and
13C{1H} central
allene carbon (δ)
νCN
νCE (E = P, As)
31P{1H} (δ)
(cm−1
)
(cm−1
)
3
4
5
−21.28
−10.70
150.85, 1JP–C = 152.3 Hz
151.05, 1JP–C = 103.0 Hz
154.25
2181
2186
2182
1600
1602
1513
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Fig. 3 Thermal ellipsoid plots of 4 and 5 at the 50% probability level. Hydrogens have been omitted for clarity.
Table 2 Selected bond distances (Å) and angles (°) for 4 and 5
Th1–C11
Th1–N2
Th1–C12
N1–C12
N2–C11
C11–E1
N2–C11–E1
C11–E1–C19
4
5
2.430(6)
2.419(5)
2.346(5)
2.364(4)
2.643(6)
2.638(6)
1.131(8)
1.128(7)
1.348(8)
1.347(7)
1.691(6)
1.822(5)
152.1(5)
150.3(4)
115.8(3)
114.5(2)
Fig. 4 Possible reaction pathways for the generation of 3, 4 and 5.
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slowly warmed the reaction while monitoring the reaction pro- internally to the residual peak at δ 128.0 ppm (C6D6). 31P NMR
gress using 31P NMR. At −80 °C we observed the formation of spectra were externally referenced to 0.00 ppm with 5% H3PO4
4, H2PTipp, (C5Me5)2Th[P(H)Tipp]2, and
a
singlet at in D2O. Infrared spectra were recorded as KBr pellets on a
−26.5 ppm. Upon heating to −70 °C the reaction was complete Perkin-Elmer Spectrum One FT-IR spectrometer. Elemental
with disappearance of the resonance at −26.5 ppm. This reson- analyses were performed at the University of California, Berke-
ance at −26.5 ppm has not been identified but it is possible ley Microanalytical Facility using a Perkin-Elmer Series II 2400
that it is 4 without a coordinated isocyanide. We saw no evi- CHNS analyzer.
dence of a transient terminal phosphinidene as no resonance
>100 ppm was observed (see ESI†).
[TippAsCl2]. A two-neck 500 mL Schlenk flask was charged
with 1-bromo-2,4,6-iPr3C6H2Br (4.00 g, 14.1 mmol), Mg ribbon
(polished and cut into small pieces, 377 mg, 15.5 mmol), and
THF (75 mL). A reflex condenser was attached under nitrogen
and 1–2 mL of 1,2-dibromoethane were added to the reaction.
The reaction was heated to reflux and allowed to react for 8 h.
Conclusion
In summary we have broadened the scope of actinide–pnicto- The Grignard reaction was allowed to cool to room tempera-
genide complexes by the isolation and characterization of new ture. A 250 mL Schlenk flask was charged with AsCl3 (2.56 g,
thorium primary phosphido and arsenido compounds. Both 14.1 mmol) and THF (30 mL) and cooled to −40 °C via a
compounds exhibited spectroscopic diagnostic features in the CO2(s)/CH3CN bath. The Grignard was added via a cannula to
infrared and heteronuclear NMR experiments. Insertion reac- the AsCl3 followed by ZnCl2 (3.84 g, 28.2 mmol). The reaction
tions of an alkyl isocyanide into the thorium–primary pnicto- mixture was allowed to stir at −40 °C for 6 h, slowly warmed to
genide bond resulted in the formation of phospha/ room temperature and allowed to stir for an additional 24 h at
arsaazaallene complexes that do not exhibit any type of room temperature. The filtrate was isolated via cannula fil-
rearrangement. Further investigation is required to elucidate tration and the white solid was extracted twice with diethyl
whether this reactivity is unique to the actinides or Lewis acids ether (2 × 30 mL) and added to the filtrate. The solution was
coordinated to two primary phosphido or arsenido ligands. concentrated and placed in a −20 °C freezer. Long colorless
Therefore group IV and alternative actinide metals are under crystals grew over a period of 36 h. The crystals were isolated
investigation.
and dried (two crops 3.35 g, 68%). 1H NMR (C6D6, 23 °C): δ 7.04
3
(s, 2H, ArH), 3.92 (sept, JH–H = 6.5 Hz, 2H, CHortho(CH3)2), 2.62
3
3
(sept, JH–H = 6.5 Hz, 1H, CHpara(CH3)2), 1.20 (d, JH–H = 6.5 Hz,
12H, CH(CH3)2-ortho), 1.10 (d, 3JH–H = 6.5 Hz, 6H, CH(CH3)2-para).
[TippAsH2]. A 3-neck 1000 mL round bottom flask was
charged with LiAlH4 (1.80 g, 47.3 mmol) and THF (50 mL). A
Experimental
General considerations
The syntheses and manipulations described below were con- 100 mL Schlenk flask was charged with TippAsCl2 (6 g,
ducted using standard Schlenk and glovebox techniques. All 17.2 mmol) and THF (50 mL). The LiAlH4 was cooled to –5 °C
the reactions were conducted in a Vacuum Atmospheres inert via a NaCl(s)/ice bath and TippAsCl2 was added to the mixture
atmosphere (N2) glovebox or a double-manifold Schlenk line. via a cannula and allowed to stir for 10 minutes. The salt bath
Toluene, 1,2-dimethoxyethane, diethyl ether and hexane were was removed and the reaction mixture was stirred at room
purchased anhydrous, stored over activated 4 Å molecular temperature for 12 h. The reaction mixture was placed in an
sieves, and sparged with nitrogen prior to use. Methylcyclo- ice bath and the excess LiAlH4 was quenched dropwise with a
hexane was dried over activated 4 Å molecular sieves and sparged degassed HCl/H2O mixture (20% HCl, extreme care should be
with nitrogen for thirty minutes prior to use. tert-Butyl iso- taken when first beginning to quench the mixture because the
cyanide was dried over 4 Å molecular sieves, freeze–evacuate– reaction is exothermic and H2(g) is evolved). The organic
thawed three times, distilled, and stored under nitrogen. phase was separated and the aqueous phase was extracted
All available reactants were purchased from suppliers twice with diethyl ether (2 × 40 mL) and the organic phases
and used without further purification. ThCl4(DME)2,47 were combined. The organic phase was dried over MgSO4 and
(C5Me5)2ThCl2,48 (C5Me5)2ThMe2,48 TippPCl2,49 H2PTipp,50 the solvent was removed under vacuum to yield the crude
MesPCl2,51 MesPH2,52 and (C5Me5)2Th[P(H)Tipp]2
(Tipp = product as a colorless viscous solid. The product can be puri-
26
2,4,6-iPr3C6H2, Mes = 2,4,6-Me3C6H2) were synthesized as pre- fied via distillation to yield a colorless liquid (4.10 g, 85%).
viously described. KPH(Mes) was prepared from H2PMes and 1H NMR (C6D6, 23 °C): δ 7.10 (s, 2H, ArH), 3.38 (s, 2H, AsH),
3
KN(SiMe3)2 in THF. Benzene-d6 and toluene-d8 (Cambridge 3.36 (sept, JH–H = 7.0 Hz, 2H, CHortho(CH3)2), 2.76 (sept,
3
Isotope Laboratories) were dried over molecular sieves and 3JH–H = 7.0 Hz, 1H, CHpara(CH3)2), 1.22 (d, JH–H = 7.0 Hz, 12H,
degassed with three freeze–evacuate–thaw cycles. All 1H and CH(CH3)2-ortho), 1.21 (d, 3JH–H = 7.0 Hz, 6H, CH(CH3)2-para).
13C NMR spectra were obtained on a 500 or 600 MHz DRX
(C5Me5)2Th[P(H)Mes]2, 1. The same procedure was
Bruker spectrometer. All 31P NMR spectra were obtained on a employed as for (C5Me5)2Th[P(H)Tipp]2 using (C5Me5)2ThCl2
1
300 MHz ARX spectrometer at 121 MHz. H NMR shifts given (287 mg, 0.500 mmol) and KP(H)Mes (200 mg, 1.05 mmol) to
1
were referenced internally to the residual solvent peak at yield 1 as a bright orange solid (217 mg, 54%). H NMR (C6D6,
1
δ 7.16 ppm (C6D5H). 13C NMR shifts given were referenced 23 °C): δ 6.99 (s, 4H, ArH), 3.80 (d, JP–H = 224 Hz, 2H, PH),
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2.67 (s, 12H, CH3-ortho), 2.33 (s, 6H, CH3-para), 1.89 (s, 30H, stir for 2 h to yield a yellow reaction mixture. The mixture was
C5Me5). 13C{1H} NMR (C6D6, 23 °C): δ 140.00 (d, 1JP–C = 18.0 Hz), filtered over Celite, concentrated to 1–2 mL and placed in a
139.16, 133.90 (the C(sp2)–H resonance was buried under the −23 °C freezer. Yellow needle crystals grew after a 48 h period,
solvent resonance), 126.77, 25.42, 20.95, 11.47. 31P{1H} NMR and were isolated and dried to yield the product (66 mg, 78%).
(C6D6, 23 °C): δ 15.37. IR (cm−1): 2910 (s), 2855 (s), 2341 (m), 1H NMR (C6D6, 23 °C): δ 7.27 (s, 2H, ArH), 4.87 (s, br, 2H,
3
1446 (s), 1433 (s), 1378 (m), 1257 (m), 1100 (m), 1067 (m) 1024 CHortho(CH3)2), 2.95 (sept, JH–H = 7.2 Hz, 1H, CHpara(CH3)2),
3
(m), 952 (w), 940 (w), 894 (w), 847 (m), 703 (w). Anal. calcd 2.16 (s, 30H, C5Me5), 1.65 (d, JH–H
= 7.2 Hz, 12H,
for C38H54P2Th: C, 56.72%; H, 6.76%. Found: C, 56.61%; CH(CH3)2-ortho), 1.36 (d, 3JH–H = 7.2 Hz, 6H, CH(CH3)2-para), 1.22
H, 6.75%.
(s, 9H, CNCMe3), 1.08 (s, br, 9H, CNCMe3). 13C{1H} NMR
(C5Me5)2Th[As(H)Tipp]2, 2. A 20 mL scintillation vial was (C6D6, 23 °C): δ 164.11 (CNCMe3), (Cipso–P could not be
1
charged with (C5Me5)2ThMe2 (100 mg, 0.188 mmol), toluene located), 152.95, 150.85 (d, JP–C = 152.3 Hz, Me3CNCPTipp),
3
(8 mL), and placed in a −23 °C freezer for 30 minutes. The vial 146.56, 122.37, 120.22, 59.80 (d, JP–C = 12.0 Hz, Me3CNCP-
3
was removed from the freezer and H2AsTipp (106 mg, Tipp), 56.81 (CNCMe3), 34.90, 33.52 (d, JP–C = 6.0 Hz), 32.41
0.378 mmol) was added dropwise and allowed to stir at room (Me3CNCPTipp), 29.14 (CNCMe3), 24.62, 23.79, 11.77. 31P{1H}
temperature for 12–14 h to yield a cherry red solution. The NMR (C6D6, 23 °C): δ −21.28. IR (cm−1): 2957 (s), 2913 (s),
solvent was removed under vacuum, extracted with hexane, fil- 2864 (s), 2304 (m), 2181(s), 1600 (m), 1450 (s), 1361 (s),
tered over Celite, concentrated to 1–2 mL and placed in a 1193 (m), 1092 (m), 1021 (m), 943 (m), 875 (m), 805 (m),
−23 °C freezer. Red prism crystals grew after 36 h, and were 723 (m), 650 (m). Anal. calcd for C45H71N2PTh: C, 59.85%;
isolated and dried to yield the product (two crops, 140 mg, H, 7.92%; N, 3.10%. Found: C, 60.05%; H 7.64%; N, 2.71%.
70%). 1H NMR (C6D6, 23 °C): δ 7.26 (s, 4H, ArH), 3.66 (sept,
(C5Me5)2Th(CNtBu)(η2-N,C)-(tBuNCPMes), 4. The same pro-
3
3JH–H = 6.6 Hz, 4H, CHortho(CH3)2), 2.95 (sept, JH–H = 7.2 Hz, cedure was employed as for 3 using 1 (100 mg, 0.124 mmol)
2H, CHpara(CH3)2), 2.61 (s, 2H, AsH), 1.98 (s, 30H, C5Me5), 1.54 and tert-butyl isocyanide (21 mg, 0.253 mmol) to yield 4 as a
3
(d, JH–H = 6.6 Hz, 24H, CH(CH3)2-ortho), 1.34 (d, 3JH–H = 7.2 Hz, yellow solid (81 mg, 80%). 1H NMR (C6D6, 23 °C): δ 7.05 (s, 2H,
12H, CH(CH3)2-para). 13C{1H} NMR (C6D6, 23 °C): δ 151.07, ArH), 3.10 (s, 6H, CH3-ortho), 2.27 (s, 6H, CH3-para), 2.16 (s, 30H,
146.69, 141.44, 127.33, 120.45, 35.77, 34.51, 24.75, 24.50, C5Me5), 1.25 (s, 9H, CNCMe3), 1.02 (s, br, 9H, CNCMe3). 13C
1
11.99. IR (cm−1): 2959 (s), 2917 (s), 2870 (s), 2089 (m), 1599 {1H} NMR (C6D6, 23 °C): δ 183.56 (d, JP–C = 56.0 Hz, Cipso–P),
1
(m), 1551 (m), 1455 (s), 1373 (m), 1307 (m), 1245 (w), 1162 (m), 163.29 (CNCMe3), 151.05 (d, JP–C = 103.0 Hz, Me3CNCPMes),
4
1098 (m), 1061 (m), 1021 (m), 934 (m) 870 (m), 805 (m), 744 142.65 (d, JP–C = 4.5 Hz), 134.41 (the C(sp2)–H resonance was
3
(m), 609 (m). Anal. calcd for C50H78As2Th: C, 56.60%; H, buried under the solvent resonance), 122.42, 59.47 (d, JP–C
=
7.41%. Found: C, 56.21%; H, 7.38%.
12.0
Hz,
Me3CNCPMes),
56.66
(CNCMe3),
31.69
(C5Me5)2Th(CNtBu)(η2-N,C)-(tBuNCPTipp), 3. A 20 mL scin- (Me3CNCPMes) 29.19 (CNCMe3), 24.58, 21.33, 11.87. 31P{1H}
tillation vial was charged with (C5Me5)2Th[P(H)Tipp]2 (91 mg, NMR (C6D6, 23 °C): δ −10.70. IR (cm−1): 2956 (s), 2913 (s),
0.0935 mmol), methylcyclohexane (5 mL) and placed in a 2304 (w), 2186 (s), 1602 (m), 1448 (s), 1355 (s), 1191 (s), 1093
−23 °C freezer for 30 minutes. The vial was removed from the (s), 1030 (s), 846 (m), 708 (m), 648 (m). C39H59N2PTh:
freezer and tert-butyl isocyanide (16 mg, 0.192 mmol) was C, 57.20%; H, 7.26%; N, 3.42%. Found: C, 57.40%; H, 6.99%;
added dropwise to the (C5Me5)2Th[P(H)Tipp]2 and allowed to N, 3.30%.
Table 3 X-ray crystallography data for complexes 1, 2, 3, and 5
1
2
3
5
TippAsCl2
CCDC deposit number
1455163
C38H54P2Th
804.79
Prism, orange
100(2)
1455164
C50H78As2Th
1061.00
Prism, red
100(2)
1455165
C45H71N2PTh
903.04
Needle, yellow
100(2)
1455166
C45H71N2AsTh
946.99
Needle, orange
100(2)
1455345
C15H23AsBr0.55Cl1.45
349.15
Prism, colorless
100(2)
ˉ
P1
Triclinic
813.6(2)
8.3739(12)
9.1197(13)
11.6208(16)
75.718(2)
71.5280(10)
81.712(2)
2
1.425
2.400
R = 0.0627
RW = 0.1803
Empirical formula
Formula weight (g mol−1
)
Crystal habit, color
Temperature (K)
Space group
Crystal system
Volume (Å3)
a (Å)
b (Å)
c (Å)
α (°)
β (°)
Pbcn
C2/c
Pnma
Pnma
Orthorhombic
3598.3(5)
11.0230(9)
15.3941(13)
21.2051(18)
90.00
90.00
90.00
4
1.486
4.257
R = 0.0211
RW = 0.0431
Monoclinic
4809.0(7)
23.195(2)
12.1067(10)
17.8732(15)
90.00
106.6350(10)
90.00
4
1.465
4.497
R = 0.0195
RW = 0.0437
Orthorhombic
5659.3(6)
28.9553(18)
14.5673(9)
13.4169(9)
90.00
90.00
90.00
4
1.060
2.687
R = 0.0317
RW = 0.0823
Orthorhombic
5712.6(6)
29.0966(19)
14.5564(9)
13.4878(9)
90.00
90.00
90.00
4
1.101
3.208
R = 0.0330
RW = 0.0741
γ (°)
Z
Calculated density (Mg m−3
)
Absorption coefficient (mm−1
Final R indices [I > 2σ(I)]
)
Dalton Trans.
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Dalton Transactions
Paper
[(C5Me5)2Th(CNtBu)(η2-N,C)-(tBuNCAsTipp)], 5. The same
6 N. R. Price and J. Chambers, in The Chemistry of Organo-
phosphorus Compounds, ed. F. R. Hartley, Chichester, 1990,
vol. 1.
7 D. E. C. Corbridge, in Phosphorus: Chemistry, Biochemistry,
and Technology, CRC Press, Boca Raton, FL, 2013, 6th edn,
p. 1473.
8 E. Rafter, T. Gutmann, F. Low, G. Buntkowsky, K. Philippot,
B. Chaudret and P. W. N. M. van Leeuwen, Catal. Sci.
Technol., 2013, 3, 595.
9 I. S. R. Karmel, M. Tamm and M. S. Eisen, Angew. Chem.,
Int. Ed., 2015, 54, 12422.
procedure was employed as for
3 using 2 (200 mg,
0.188 mmol) and tert-butyl isocyanide (32 mg, 0.385 mmol) to
yield 5 as an orange solid (146 mg, 82%). X-ray quality crystals
1
were grown from a toluene/hexane mixture at −23 °C. H NMR
(C6D6, 23 °C):
δ 7.32 (s, 2H, ArH), 4.84 (s, br, 2H,
3
CHortho(CH3)2), 2.98 (sept, JH–H = 7.2 Hz, 1H, CHpara(CH3)2),
2.16 (s, 30H, C5Me5), 1.67 (d, 3JH–H = 7.2 Hz, 6H, CH(CH3)2-ortho),
3
1.38 (d, JH–H = 7.2 Hz, 3H, CH(CH3)2-para), 1.24 (s, 9H,
CNCMe3), 0.97 (s, br, 9H, CNCMe3). 13C{1H} NMR (C6D6,
23 °C): δ 164.41 (CNCMe3), (Cipso–As could not be located),
154.25 (Me3CNCAsTipp), 154.05, 146.65, 122.65, 120.24, 10 T. W. Hayton, J. M. Boncella, B. L. Scott, P. D. Palmer,
60.30 (Me3CNCAsTipp), 57.01 (CNCMe3), 35.63, 34.90, 32.03 E. R. Batista and P. J. Hay, Science, 2005, 310, 1941.
(Me3CNCAsTipp), 29.01 (CNCMe3), 26.91, 24.67, 11.79. 11 D. M. King, F. Tuna, E. J. L. McInnes, J. McMaster,
IR (cm−1): 2958 (s), 2917 (s), 2865 (s), 2182 (m), 1513 (m),
1452 (s), 1367 (m), 1312 (m), 1214 (m), 1109 (m), 1027 (m), 877 (w),
W. Lewis, A. J. Blake and S. T. Liddle, Science, 2012, 337,
717.
805 (m), 624 (m). Anal. calcd for C45H71N2AsTh: C, 57.08%; 12 N. H. Anderson, S. O. Odoh, Y. Yao, U. J. Williams,
H, 7.56%; N, 2.96%. Found: C, 58.72%; H, 7.45%; N, 2.71%.
B. A. Schaefer, J. J. Kiernicki, A. J. Lewis, M. D. Goshert,
P. E. Fanwick, E. J. Schelter, J. R. Walensky, L. Gagliardi
and S. C. Bart, Nat. Chem., 2014, 6, 919.
Crystallographic data collection and structure determination
13 N. H. Anderson, H. Yin, J. J. Kiernicki, P. E. Fanwick,
E. J. Schelter and S. C. Bart, Angew. Chem., Int. Ed., 2015,
54, 9386.
14 B. M. Gardner, G. Balázs, M. Scheer, F. Tuna,
E. J. L. McInnes, J. McMaster, W. Lewis, A. J. Blake and
S. T. Liddle, Angew. Chem., Int. Ed., 2014, 53, 4484.
15 D. S. J. Arney, R. C. Schnabel, B. C. Scott and C. J. Burns,
J. Am. Chem. Soc., 1996, 118, 6780.
The selected single crystal was mounted on nylon cryoloops
using viscous hydrocarbon oil. X-ray data collection was per-
formed at 100(2) K. X-ray data were collected on a Bruker CCD
diffractometer with monochromated Mo-Kα radiation (λ =
0.71073 Å). The data collection and processing were performed
using a Bruker Apex2 suite of programs.53 The structures were
solved by direct methods and refined by full-matrix least-
squares methods on F2 using the Bruker SHELX-2014/7
program.54 All non-hydrogen atoms were refined with an-
isotropic displacement parameters. All hydrogen atoms were
placed at calculated positions and included in the refinement
using a riding model. Thermal ellipsoid plots were prepared
using X-seed55 with 50% of probability displacements for non-
hydrogen atoms. Crystal data and details of data collection for
complexes 1, 2, 3, and 5 are provided in Table 3.
16 M. R. Duttera, V. W. Day and T. J. Marks, J. Am. Chem. Soc.,
1984, 106, 2907.
17 D. Patel, F. Tuna, E. J. L. McInnes, W. Lewis, A. J. Blake and
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18 N. Tsoureas, A. F. R. Kilpatrick, O. T. Summerscales,
J. F. Nixon, F. G. N. Cloke and P. B. Hitchcock, Eur. J. Inorg.
Chem., 2013, 2013, 4085.
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Acknowledgements
We gratefully acknowledge the U.S. Department of Energy,
Office of Science, Early Career Research Program under award
DE-SC-0014174 for support of this work.
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