Isolatable organophosphorus(III)-tellurium heterocycles

Article abstract of DOI:10.1002/chem.201303884

A new structural arrangement Te₃(RP^III)₃ and the first crystal structures of organophosphorus(III)-tellurium heterocycles are presented. The heterocycles can be stabilized and structurally characterized by the appropriate choice of substituents in Te_m(P ^IIIR)_n (m=1: n=2, R=OMes* (Mes=supermesityl or 2,4,6-tri-tert-butylphenyl); n=3, R=adamantyl (Ad); n=4, R=ferrocene (Fc); m=n=3: R=trityl (Trt), Mesor by the installation of a P^V ₂N₂ anchor in RP^III[TeP^V(tBuN)(μ- NtBu)]₂ (R=Ad, tBu). Copyright

Full text of DOI:10.1002/chem.201303884

DOI: 10.1002/chem.201303884
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&
Inorganic Heterocycles
Isolatable Organophosphorus(III)–Tellurium Heterocycles
Andreas Nordheider,[a, b] Tristram Chivers,[b] Oliver Schçn,[c] Konstantin Karaghiosoff,[c]
Kasun S. Athukorala Arachchige,[a] Alexandra M. Z. Slawin,[a] and J. Derek Woollins*[a]
Abstract: A new structural arrangement Te3(RPIII)3 and the
first crystal structures of organophosphorus(III)–tellurium
heterocycles are presented. The heterocycles can be stabi-
lized and structurally characterized by the appropriate
choice of substituents in Tem(PIIIR)n (m=1: n=2, R=OMes*
(Mes*=supermesityl or 2,4,6-tri-tert-butylphenyl); n=3, R=
adamantyl (Ad); n=4, R=ferrocene (Fc); m=n=3: R=trityl
(Trt), Mesor by the installation of a PV N2 anchor in RPIII[TePV-
2
(tBuN)(m-NtBu)]2 (R=Ad, tBu).
Introduction
These pathways produced a series of organophosphorus(III)–
tellurium heterocycles with different structural arrangements,
as depicted in Figure 1. To date, the findings regarding these
systems by du Mont,[6,7] Karaghiosoff[8,9] and Tokitoh[10] lead to
the following conclusions:
Compounds, such as Lawesson’s reagent [(4-MeOC6H4)P=S(m-
S)]2 (LR)[1] and Woollins’ reagent [PhP=Se(m-Se)]2 (WR),[2] illus-
trate that organophosphorus–sulfur and -selenium compounds
have been studied extensively not least because of their inter-
esting reactivity towards organic compounds.[3,4] In contrast,
organophosphorus–tellurium heterocycles Tem(RP)n have been
only sporadically investigated.[5] The systems were usually ob-
tained as mixtures and characterized by a combination of solu-
tion-state 31P and 125Te NMR, as well as by mass spectrome-
try.[6–9]
The different synthetic approaches that were developed to
generate organophosphorus(III)–tellurium heterocycles include
reactions of
i) RPÀSi reagents [R=tBu] with tellurium.[6,7]
ii) RPCl2 [R=tBu, R’2N (R’=iPr, Cy, Ph)] with Na2Te, Li2Te2 or Te-
(SiMe3)2.[6–9]
iii) tBu(Cl)PÀP(Cl)tBu with Na2Te.[5,6]
iv) nBu3PTe with the diphosphene TbtP=PFc (Tbt=2,4,6-tris-
[bis(trimethylsilyl)methyl]-phenyl).[10]
Figure 1. Structural arrangements of organophosphorus(III)–tellurium het-
erocycles Tem(RP)n, including this work. The existence of Te2(RP)4 is tentative
based on limited NMR data.[7]
[a] A. Nordheider, K. S. Athukorala Arachchige, A. M. Z. Slawin,
Prof. Dr. J. D. Woollins
i) Three-, four- and five-membered rings containing one Te
atom and five- and six-membered rings incorporating one
Te-PIII-Te unit and two PIII-Te-PIII units, respectively, are pos-
sible (see Figure 1, left-hand and centre columns).
EaStCHEM School of Chemistry, University of St Andrews
St Andrews, Fife, KY16 9ST (UK)
Fax: (+44)1334-463834
E-mail: jdw3@st-and.ac.uk
ii) Stable heterocycles containing both terminal (exo) and
bridging (endo) Te atoms, that is, a P=Te(m-Te) unit, com-
pared to LR and WR, are unlikely.
iii) CF3 substituents on P improve the stability of the rings
with respect to loss of Te in solution, whereas NR2 groups
do not have the same stabilizing influence.
[b] A. Nordheider, T. Chivers
Department of Chemistry, University of Calgary
Calgary, AB T2N 1N4 (Canada)
[c] O. Schçn, K. Karaghiosoff
Department of Chemistry and Pharmacy, University of Munich
81377 Munich-Grosshadern (Germany)
Supporting information for this article is available on the WWW under
http://dx.doi.org/10.1002/chem.201303884.
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iv) The pure 3- and 4-membered rings that were isolated Te-
(tBuP)n (n=2, 3) are yellow or red liquids at room tempera-
ture.
however be recrystallized from hot toluene to give pure 1a in
low yield. In contrast, the reaction of AdPCl2 with Na2Te2 under
similar conditions gave the telluradiphosphirane (2b) as the
main product and the telluratriphosphetane (2a) as a minor
product (31P NMR analysis); 2a was isolated as red crystals in
approximately 5% yield (Scheme 1).[14]
v) The reported compounds are air sensitive; some show
light sensitivity and thermal instability, which complicates
the isolation and characterization.
vi) No solid-state structures have been reported to date.
Similarly, Mes*OPCl2 was reacted with Na2Te2 to give the tel-
luradiphosphirane 3a, which was isolated in a yield of 37%
after recrystallization from hexane (Scheme 2).
Herein, we describe two new synthetic approaches to
organophosphorus(III)–tellurium heterocycles that have led to
1) the first examples of ring systems that incorporate an equal
number of alternating P and Te atoms, that is, Te3(PR)3 (R=
Mes*, Trt; Trt=trityl=ÀCPh3); 2) the first solid-state structural
characterizations of Tem(RP)n rings including Te3(PR)3, Te(PR)2
(R=OMes*) and Te(PR)3 (R=Ad) Te(PR)4 (R=Fc); and 3) P2N2-
stabilized organophosphorus(III)–tellurium rings.
Scheme 2. Reaction of Mes*OPCl2 with Na2Te2 in THF.
Results and Discussion
Synthesis and multinuclear NMR spectra of
organophosphorus(III)–tellurium heterocycles
Finally, the reaction of Mes*PCl2 and TrtPCl2 with an equimo-
lar amount of Na2Te2 gave rise to the new tritelluratriphosphor-
inanes 4a (Mes*PTe)3 and 5a (TrtPTe)3, which were character-
ized by NMR spectroscopy. For the reaction with Mes*PCl2, the
disphosphene (Mes*P=PMes*) was observed as a major by-
product and together with elemental Te also as the decompo-
sition product, when left in solution for more than 24 h
(Scheme 3).[15] For the TrtPCl2 reactions, a telluratriphosphetane
5b was identified as a minor product besides other unknown
compounds (Scheme 3). In contrast to 1a, 2a, 2b and 3a,
these compounds (4a, 5a, 5b) are highly air sensitive and
slightly light sensitive.
The first synthetic approach involves the reaction of RPCl2 (R=
Fc, Ad, Mes*O, Mes*, Trt) with Na2Te2 in THF (Scheme 1). These
The 31P NMR spectrum of 1a exhibits
a second-order
AA’MM’ pattern (considering the 125Te-containing isotopomer,
it expands to an AA’MM’X spin system). The characteristic
values (shift and coupling constants) were calculated by itera-
tive fitting, as shown in Figure 2.[16]
Scheme 1. Reaction of a) FcPCl2 and b) AdPCl2 with Na2Te2 in THF.
R groups were chosen, because they provide signifi-
cant steric bulk (Mes*, Trt), and the Fc analogue of
LR has proved to be very stable.[11] Furthermore, an
adamantyl ligand at a phosphorus atom was shown
to have similar reactivity and characteristics to the
tert-butyl ligands. The reactions of the adamantyl-
substituted compounds are usually slower, but crys-
tallization is favoured in comparison to tert-butyl
compounds.[12] The Mes*O substituent was used as
an example of a bulky electronegative anionic ligand
system at the phosphorus atom.
Treatment of FcPCl2 with an equimolar amount of
Na2Te2 in THF at À788C gave 1a as the major prod-
[13]
uct with the cyclo-pentaphosphane (FcP)5 as a by-
product, which was identified by X-ray crystallogra-
phy (Scheme 1). The 2,3,4,5-tetraferrocenyl-1-tellura-
2,3,4,5-tetraphospholane (1a) was isolated as an
orange-to-red solid with low solubility, which can Scheme 3. Reaction of a) Mes*PCl2 and b) TrtPCl2 with Na2Te2 in THF.
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(260 Hz)[10] or Karaghiosoff et al. (285.2 Hz).[9] The observations
are consistent with the triplet resonance in the 125Te NMR spec-
trum at 7.7 ppm, which also shows a significantly low-field
shift when compared to the other reported P2Te systems and
2b.
The 31P NMR spectra of 4a and 5a displayed singlets at d=
57.7 ppm (4a) and 117.9 ppm (5a) with a characteristic pattern
for the A part of an A2A’X spectrum, shown in Figure 3. The
coupling constants were calculated by iterative fitting of the si-
1
mulated spectra depicted in A, C of Figure 3. The JPÀTe values
are rather large with À441.7 Hz (4a) and À398.7 Hz (5a), re-
spectively (negative signs are derived from iterative fitting).
2
The JPÀP values were shown to be 325.0 Hz (4a) and 257.1 Hz
3
2
(5a), JPÀTe could not be observed. The large JPÀP value is pre-
sumably due to a correlating alignment of the free electron
pairs at the phosphorus(III) atoms, which would be consistent
with a chair-like conformation of the P3Te3 rings with the sub-
stituents on the phosphorus atoms in equatorial positions. This
was confirmed by a single-crystal X-ray structure of 5a. The
125Te NMR spectra are multiplets at 774.2 ppm (4a) and
598.9 ppm (5a) consistent with the simulation of an A2A’X spin
system (Figure 4).
The 31P NMR spectrum of telluratriphosphetane 5b showed
two resonances, a doublet at d=131.8 ppm and a triplet at
Figure 2. 31P NMR spectrum (202.47 MHz) of 1a: A) AA’MM’ spectrum calcu-
lated by iterative fitting and B) experimental spectrum.[16]
1
82.1 ppm. In comparison to 2a, a small JPÀTe coupling was visi-
1
ble at 72.2 Hz, in the form of satellites at the doublet. The JPÀP
The P1/P1’ resonances appear at d=84.5 ppm revealing
value of 187.0 Hz is slightly larger than for 2a (169.0 Hz) or the
tBu-substituted derivative (172.6 Hz),[6] but smaller than those
with CF3 substituents (248.7 Hz).[9]
2
a
1JP1ÀP2-coupling of À305.1 Hz, a JP1ÀP2’/P1’ÀP2 coupling of
2
31.0 Hz and a JP1ÀP1’ coupling of 8.0 Hz. The P2/P2’ resonances
1
were observable at 69.6 ppm with a JP2ÀP2’ coupling of
À339.0 Hz.[17] The very poor solubility of 1a precluded the ob-
servation of 125Te satellites, as well as characterization by
125Te NMR analysis.
X-ray structures of organophosphorus(III)–tellurium hetero-
cycles
The adamantyl derivative 2a showed a first order A2M-type
31P NMR spectrum (considering the 125Te-containing isotopomer
it expands to an A2MX-type spectrum), consistent with an all-
trans orientation of the phosphorus substituents. The P2/P4
atoms appear as a doublet at À66.6 ppm, and the P3 atom as
Crystals of 2,3,4,5-tetraferrocenyl-1-tellura-2,3,4,5-tetraphospho-
lane (1a) were isolated from toluene at À408C as red prisms.
The crystal structure of 1a reveals that the P4Te ring is non-
planar with ferrocenyl groups alternating above and below the
plane of the ring (all-trans conformation; Figure 5). The PÀTe
bond length of 2.503(6) ꢁ is significantly shorter than the value
of 2.565 ꢁ reported for the PIIIÀTe single bond in the acyclic
1
1
a triplet at À26.3 ppm. The JPÀP coupling is 169.0 Hz; the JPÀTe
coupling was not observed, possibly due to its surprisingly
very low value of <8 Hz. The 125Te NMR spectrum of 2a
showed a doublet at À461.1 ppm (2JPÀTe =80 Hz). The 31P NMR
spectrum of 2b consists of a singlet (A2X spin system) at
À79.8 ppm accompanied by a set of tellurium satellites (125Te,
[18]
compound Te[P(NiPr2)2]2, but similar to that found for a cyclic
tritelluride anchored by PV N2 rings (d(PÀTe) 2.532–
2
2.540(1) ꢁ).[19] The PÀP bond lengths of 2.188(8) ꢁ and
2.163(8) ꢁ are slightly shorter than those in the related cyclo-
pentaphosphane (FcP)5.[13]
I=1= , 7.1%), with JPÀTe =220.6 Hz. In the 125Te NMR spectrum,
1
2
one resonance at À818.3 ppm (t, 1JPÀTe =218.4 Hz) was ob-
Single crystals of 2,3,4-tris(adamantyl)-1-tellura-2,3,4-triphos-
phetane (2a) were isolated from THF after storing the deca-
nted reaction mixture at À408C for about two weeks
(Figure 6). Two independent molecules with similar structural
parameters are present in the unit cell (Z=8). The PÀTe bond
lengths of 2.502(2) to 2.516(2) ꢁ are close to that found for 1a.
However, the PÀP bond lengths in 2a are slightly longer than
those in the corresponding cyclo-tetraphosphane (AdP)4 (d(PÀ
P) 2.2417(15)–2.2423(15) ꢁ).[20] The four-membered P3Te ring is
non-planar and the adamantyl ligands adopt an all-trans con-
formation (Figure 6). The ring shows a torsion angle of 161.68
compared to 151.78 in (AdP)4.[20]
served. The chemical shifts and coupling constants for 2a and
b are in good agreement with the reported values of the cor-
responding tBu-substituted derivatives, reported by du Mont
et al.[6]
A single resonance at 78.5 ppm was observed in the
31P NMR spectrum of 3a (as in 2b a A2X spin system), which is
shifted significantly to low field compared to 2b, presumably
due to the electronegativity of the Mes*O substituent. The tel-
1
lurium satellites revealed a coupling constant of JPÀTe of
396.9 Hz, which is quite high compared to 2b or the deriva-
tives reported by du Mont et al. (229 Hz),[6] Tokitoh et al.
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Figure 3. 31P NMR spectra (109.37 MHz) of 4a (A and B) and 5a (C and D). A) and C): A-parts of the A2A’X spectra calculated by iterative fitting; B) and D) ex-
perimental spectra.
Figure 4. 125Te NMR spectra (85.24 MHz) of 4a (A and B) and 5a (C and D). A) and C) X-part of the A2A’X spectra calculated by iterative fitting; B) and D) exper-
imental spectra.
The P-P-P-angle is at 93.19(12)8 the largest endocyclic angle
and also demonstrates the distortion as a consequence of the
Te incorporation when compared to the tetrakis-adamantyl-
cyclo-tetraphosphane (P-P-P 85.58(6)–87.10(6)8). The P-Te-P-
angle is 808 and thus the smallest angle within the ring
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Figure 5. A) X-ray crystal structure of 1a. Hydrogen atoms were omitted for
clarity. Selected bond lengths [ꢁ] and angles [8]: Te1ÀP1 2.503(6), P1ÀP2
2.188(8), P2ÀP2’ 2.163(8), P1ÀC1 1.84(3), P2ÀC11 1.83(3); P1-Te1-P1
104.89(19), Te1-P1-P2 100.9(3), Te1-P1-C1 94.7(7), P1-P2-P2’ 111.2(3), P2-P1-C1
99.4(7), P2’-P2-C11 103.5(7). B) Packing along the a axis.
Figure 7. X-ray crystal structure of 3a. Hydrogen atoms were omitted for
clarity. Selected bond lengths [ꢁ] and angles [8]: Te1ÀP1 2.4794(9), Te1ÀP2
2.4629(10), P1ÀP2 2.2473(10), P1ÀO1 1.6639(15), P2ÀO2 1.6675(17); P1-Te1-
P2 54.09(3), Te1-P1-P2 62.58(3), Te1-P2-P1 63.33(3), Te1-P1-O1 107.54(6), P2-
P1-O1 101.36(6), Te1-P2-O2 106.42(7), P1-P2-O2 102.28(7).
Figure 6. X-ray crystal structure of 2a. Hydrogen atoms were omitted for
clarity. Two distinct molecules within the unit cell (numbering scheme for
the second independent molecule in parentheses): Selected bond lengths
[ꢁ] and angles [8]: Te1ÀP3 2.502(2), Te1ÀP5 2.516(2), Te2ÀP4 2.507(2), Te2ÀP6
2.509(2), P3ÀP7 2.224(3), P4ÀP8 2.224(3), P5ÀP7 2.226(3), P6ÀP8 2.227(3),
P3ÀC41 1.867(8), P4ÀC11 1.873(8), P5ÀC31 1.874(8), P6ÀC21 1.874(8), P7ÀC55
1.881(8), P8ÀC1 1.878(8); P3-Te1-P5 80.23(7), P4-Te2-P6 80.65(7), P7-P3-Te1
90.12(9), P8-P6-Te2 89.50(9), P7-P5-Te1 89.71(9), P8-P4-Te2 89.59(9), P3-P7-P5
93.19(11), P4-P8-P6 93.64(11).
Figure 8. X-ray crystal structure of 5a. Hydrogen atoms and solvent mole-
cules (four per P3Te3 system, eight per unit cell) were omitted for clarity. Two
distinct molecules within the unit cell (numbering Scheme for the second in-
dependent molecule in parentheses): Selected bond lengths [ꢁ] and angles
[8]: Te1ÀP1 2.502(3), Te1ÀP2 2.488(3), Te2ÀP2 2.508(3), Te2ÀP3 2.474(3), Te3À
P1 2.482(3), Te3ÀP3 2.491(3), Te4ÀP4 2.482(3), Te4ÀP5 2.476(4), Te5ÀP5
2.492(4), Te5ÀP6 2.492(3), Te6ÀP4 2.498(3), Te6ÀP6 2.517(4), PÀC 1.917(10)-
1.938(12); P1-Te1-P2 83.41(9), P2-Te2-P3 82.52(9), P1-Te3-P3 80.94(9), P4-Te4-
P5 81.80(10), P5-Te5-P6 82.51(10), P4-Te6-P6 81.70(10), Te1-P1-Te3 103.02(11),
Te1-P2-Te2 104.45(11), Te2-P3-Te3 105.48(11), Te4-P4-Te6 105.67(11), Te4-P5-
Te5 102.15(12), Te5-P6-Te6 102.10(12), Te-P-C 101.0(4)-105.6(4).
system. For compound 1a, no intermolecular Te···Te interac-
tions were observed.
Yellow crystals of 3a were isolated from a recrystallization
by using hexane at À408C. The X-ray structure shown in
Figure 7 reveals a three-membered P2Te ring system with com-
paratively short PÀTe distances of 2.4629(10)–2.4794(9) ꢁ and
a slightly longer PÀP distance than observed in 1a and 2a.
The smallest angle within the ring system is as in 2a the P-Te-
P angle at 54.09(3)8. The Mes*O ligands on the phosphorus are
in a trans position revealing a O-P-P-O torsion angle of
153.618.
crystal X-ray analyses. The structure and selected parameters
are depicted in Figure 8.
Two distinct molecules, as well as eight THF solvent mole-
cules, are present in the unit cell. The P3Te3 ring crystallizes in
the chair conformation, in which the bulky trityl ligands are
able to take the sterically advantageous equatorial positions,
Excitingly, a recrystallization of 5a from THF gave orange
prisms of the first tritelluratriphosphorinane suitable for single-
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and P1’ nuclei become magnetically inequivalent), showing
a triplet at 89.5 (6a), 93.9 ppm (7a), and a doublet at À129.0
(6a), À129.6 ppm (7a). Interestingly, the one-bond PÀTe cou-
1
pling constants involving P2 and P1 differ remarkably, JP2ÀTe
=
1
420 (6a), 418 Hz (7a) and JP1ÀTe =1073 (6a), 1073 Hz (7a) de-
spite the close similarity in PÀTe bond lengths (see below). The
1
disparity in J values is likely attributable to the difference in
formal oxidation states of the two phosphorus atoms; the low
value for the former is consistent with those found for PIII–Te
compounds in this (see above) and previous work,[6,8,9,24]
whereas values>1000 Hz were observed for ditelluro deriva-
Figure 9. a) X-ray crystal structure of 5a showing the chair-like conformation
and b) packing of 5a along the a axis including the THF molecules (eight
per unit cell); purple=P, green=Te and red=O.
tives of the PV N2 ring.[19,23,25] The 125Te NMR spectra displayed
2
a doublet of doublets pattern centred at 368.5 (6a), 423.4 ppm
1
as shown in Figure 9A. The only structure of a heavier chalco-
(7a) with JPÀTe values that corroborate those found in the
gen PIII Ch3 system in the literature is a P3S3 ring reported by
31P NMR spectra.
3
Goldwhite and co-workers;[21] P3Se3 rings are unknown in the
The molecular structure of 6a (Figure 10) contains a Te-PIII-Te
literature. The P3S3 system adopts a chair conformation in con-
unit bridging a PV N2 ring compared to the derivatives 1,3-
2
trast to the few examples of PIII O3 systems.[22]
Te2(PR)3 (R=tBu, CF3), which have been tentatively identified
by NMR spectroscopy.[7,9]
3
The PÀTe bond length of 5a range from 2.474(3) to
2.517(4) ꢁ, similar to those in the structures of 1a, 2a and 3a.
The P-Te-P angles are between 80.94(9) and 82.52(9)8 and thus
significantly smaller than the Te-P-Te angles (102.10(12)–
105.67(1)8).
The packing along the a axis is depicted in Figure 9B, show-
ing that the sterically demanding trityl substituents shield the
P3Te3 rings from each other, so that no interactions between
the phosphorus(III)–tellurium rings are possible.
The PÀTe bond lengths (d(P1ÀTe1) 2.512(3) ꢁ; d(P2ÀTe1)
2.508(3) ꢁ) are equal within experimental error, despite the dif-
ference in oxidation states of these phosphorus atoms. The X-
ray structure of 7a although disordered showed similar fea-
tures to those described for 6a.[26]
Synthesis, NMR spectra and X-ray structures of P2N2-stabi-
lised organophosphorus(III)–tellurium heterocycles
The second synthetic pathway to organophosphorus–tellurium
heterocycles utilises the reaction of RPCl2 (R=Ad, tBu) with [Li-
(TMEDA)]2[tBuN(Te)P(m-NtBu)2P(Te)NtBu)][23]
,
(TMEDA=tetra-
methylethylenediamine), a dianionic reagent that has proved
to be effective in the preparation of a cyclic tritelluride by
metathesis with TeCl2·TMTU (TMTU=tetramethylthiourea;
Scheme 4).[19]
The reactions of RPCl2 (R=Ad, tBu) with [Li(TMEDA)]2-
[tBuN(Te)P(m-NtBu)2P(Te)NtBu)] in toluene at À788C produced
6a as orange platelets and 7a as orange prisms, respectively,
which were identified by multinuclear NMR spectroscopy and
mass spectrometry, elemental analyses and single-crystal X-ray
analyses.
The 31P NMR spectra of 6a and 7a are both characterized by
a A2M spin system (with the 125Te-containing isotopomer, it ex-
pands to an AA’MX-type spectrum, in which the isochronus P1
Figure 10. X-ray crystal structure of 6a. Hydrogen atoms were omitted for
clarity. Selected bond lengths [ꢁ] and angles [8]: Te1ÀP1 2.512(3), Te1ÀP2
2.508(3), P1ÀN1 1.503(9), P1ÀN2 1.689(7), P1ÀN3 1.701(8), P2ÀC11 1.897(6);
P1-Te1-P2 91.51(10), Te1-P1-N1 118.5(4), Te1-P1-N2 103.9(4), Te1-P1-N3
105.0(5), Te1-P2-Te1’ 108.81(16), P1-N2-P1’ 96.5(5), P1-N3-P1’ 95.6(6).
Conclusion
The heterocycles 1a, 2a, 3a, 5a, 6a and 7a represent the first
structurally characterized organophosphorus(III)–tellurium het-
Scheme 4. Reaction of [tBuN(Te)P(m-NtBu)2P(Te)NtBu)][Li(TMEDA)]2 with
AdPCl2 and tBuPCl2 in toluene.
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solubility; MS: m/z calcd for [CI+]: 992.8 [M+ +H]; found: 992.9;
HRMS [APCI (ASAP)]: m/z, calcd for 994.8304 [M+ +H]; found:
994.8303 [M+ +H]; elemental analysis calcd (%) for C40H36P4TeFe4:
C 48.45, H 3.66; found: C 48.35, H 3.73.
erocycles. The reasonable thermal, air and light stability of
these ring systems will facilitate investigations of their reactivi-
ty and coordination chemistry. In particular, the ligand behav-
iour of 1a, 2a, 3a and 5a can now be compared with the very
limited information on metal complexes of Te(PR2)2.[27] From an-
other perspective, the two Te and one PIII donor atoms in 6a
and 7a offer the possibility of different coordination modes
compared to 1a, 2a, 3a and 5a. Compounds 4a and 5a are
the first representatives of heterocycles of the type Tem(PR)n
(m=n) with an equal number of alternating phosphorus and
tellurium atoms. Their thermal, air and light stability are signifi-
cantly lower than those of the phosphorus-rich ring systems
Tem(PR)n, in which n>m.
Synthesis of Te(AdP)3 (2a) and 2b Te(AdP)2 (2b)
[29]
Procedure as for 1a by using AdPCl2 (500 mg, 2.1 mmol) and
Na2Te2 (633 mg, 2.1 mmol). After the clear red solution had been
decanted, it was concentrated and stored at À408C. After 14 days,
crystals of 2a appeared, which were filtered off and dried under
vacuum (yield: <5%). The solvent was removed from the filtrate,
and the solid material was washed with cold pentane to give 2b
(yield: 36%).
Data for 2a: 31P NMR (161.98 MHz, [D8]THF): d=À66.6 (1J(P,P)=
166.7 Hz), À26.3 ppm (1J(P,P)=166.7 Hz); 125Te NMR (85.24 MHz,
[D8]THF): d=À461.1 ppm (1J(P,Te)= <8 Hz, 2J(P,Te)=80 Hz); MS
(EI+): m/z calcd for 628.2 [M]+ ; found: 628.2 [M+]; HRMS (EI+): m/z
calcd 620.1759 [M+]=C30H45P3122Te1; found: 620.1752 [M+].
Although Na2Te2 was found to be the most effective source
of tellurium in salt-elimination reactions, it is notable that no
PÀTe heterocycles containing a -Te-Te- linkage were isolated or
detected in solution (by NMR spectroscopy).
Data for 2b: M.p. >114 8C (decomp); 31P NMR (161.98 MHz,
[D8]THF): d=À79.8 ppm (s, 1J(P,Te)=220.6 Hz); 125Te NMR
(85.24 MHz, [D8]THF): d=À818.3 ppm (s, 1J(P,Te)=218.4 Hz); MS
(EI+): m/z calcd for 462.1 [M+]; found: 462.0 [M]+.
Experimental Section
All synthetic manipulations were performed under an atmosphere
of dry argon by using standard Schlenk-line techniques and/or
a Safron glove box running with argon unless otherwise stated. All
glass apparatus were stored in a drying oven (1208C) and flame
dried in vacuo (10À3 mbar) before use. Dry solvents were collected
from an MBraun solvent system under a nitrogen atmosphere and
stored in Schlenk flasks over 4 ꢁ molecular sieves. All chemicals
were purchased from Sigma Aldrich, ABCR, Acros Organics and
Synthesis of Te(Mes*OP)2 (3a)
[30]
Procedure as for 1a by using Mes*OPCl2 (500 mg, 1.4 mmol) and
Na2Te2 (415 mg, 1.4 mmol). After the 20 h of stirring at RT, the THF
was removed, and n-hexane (25 mL) was added. The suspension
was stirred for 30 min, filtered, and the filtrate was concentrated to
about 8 mL. The yellow solution was stored at À408C to give
yellow crystals after three days. The crystals were filtered off and
dried under vacuum, the filtrate again concentrated and left at
À408C for a second batch of crystals. The yellow material was
dried under vacuum for 3 h resulting in an overall yield of 37%.
Strem Chemicals Inc. unless otherwise stated. Solution H, 13C{1H},
1
31P{1H} and 125Te{1H} NMR spectra were recorded by using a JEOL
DELTA EX 270, a BRUKER Avance II 400 or a BRUKER Avance III 500
1
spectrometer. H and 13C{1H} NMR data were referenced to TMS as
internal standard, 85% H3PO4 was used as an external standard for
31P{1H} NMR and Ph2Te for 125Te{1H} NMR spectra, all NMR data were
collected at 258C. Mass spectrometry was performed on a MICRO-
MASS LCT (ES) and MICROMASS GCT (EI, CI) device. Elemental anal-
ysis was performed by a CARBO ERBA CHNS analyser as long as
the compounds were stable enough at RT for measurements. Melt-
ing or decomposition points were determined by sealing the
sample in capillaries and heating by using a Stuart SMP 30 melt-
ing-point apparatus.
1
M.p. >1268C (decomp); H NMR (500.13 MHz, [D8]THF): d=7.31 (s,
2H), 1.50 (s, 18H), 1.33 ppm (s, 9H); 31P NMR (202.47 MHz, [D8]THF):
d=78.5 ppm
(s,
1J(P,125Te) =396.9 Hz,
1J(P,123Te) =332.1 Hz);
125Te NMR (85.24 MHz, [D8]THF): d=7.7 ppm (t, 1J(P,125Te) =
394.6 Hz); MS (EI+): m/z calcd for 453.1 [M+ÀOMes*], 601.2 [M+
À2tBu+H], 262.2 [OMes*+ +H]; found: 453.0 [M+ÀOMes*], 601.1
[M+À2tBu+H]; 262.2 [OMes*+ +H]; elemental analysis calcd (%)
for C36H58O2P2Te: C 60.69, H 8.21, found: C 60.72, H 8.13.
Synthesis of Te3(Mes*P)3 (4a)
Synthesis of Te(FcP)4 (1a)
[15,31]
[28]
Procedure as for 1a by using Mes*PCl2
(500 mg, 1.4 mmol)
In a 100 mL Schlenk flask, Na2Te2 (525 mg, 1.7 mmol) was sus-
and Na2Te2 (434 mg, 1.4 mmol). After the clear yellow solution had
been decanted, the solvent was removed. The mixture was dis-
solved in n-hexane and filtered, followed by a removal of the n-
hexane. The analysed mixture mainly contained Mes*P=PMes*
(55%) and 4a (40%). A recrystallization from n-hexane gave
orange crystals of Mes*P=PMes*, the main decomposition product
pended in dry THF (10 mL). The suspension was cooled to À788C.
A solution of FcPCl2 (500 mg, 1.7 mmol) in dry THF (10 mL), also
maintained at À788C, was added dropwise (5 min) by cannula
with stirring. Stirring was continued for 3 h at that temperature
and then at 208C for another 20 h. The reaction mixture was cen-
trifuged, and the clear yellow solution was decanted and stored
for 3 days at À208C under an argon atmosphere until a green pre-
cipitate was formed. The solid product was removed by filtration
and washed with THF. The residue was heated in boiling toluene
for 2 h, and the solution was filtered hot (to remove (FcP)5) and
stored at À208C overnight to give 2,3,4,5-tetraferrocenyl-1-tellura-
2,3,4,5-tetraphospholane as red crystals (yield: 9%). M.p. >2008C;
31P NMR (202.47 MHz, [D8]THF): d=84.5 (m, 1J(P1,P2)=À305.1 Hz;
1
of 4a. 31P NMR (109.37 MHz, [D8]THF): d=57.7 ppm (s, J(P,125Te) =
À441.7 ppm (2J(P,P)=325.0 Hz); 125Te NMR (85.24 MHz, [D8]THF):
d=774.2 ppm (m, 1J(P,125Te) =442.0 Hz); MS (EI+): only fragments
were observed: m/z calcd for 277.2 [PMes*+ +H]; found: 277.1
[PMes*+ +H].
Synthesis of Te3(TrtP)3 (5a) and Te(TrtP)3 (5b)
2J(P1,P2’/P1’,P2)=31.0 Hz,
2J(P1,P1’)=12.0 Hz),
69.6 ppm
(m,
1
2
[32]
1J(P1,P2)=À305.1 Hz; J(P2,P2’)=À339.0 Hz, J(P1,P2’/P1’,P2)=31.0 Hz)
Procedure as for 1a by using TrtPCl2 (500 mg, 1.5 mmol) and
ppm; 125Te NMR (85.24 MHz, [D8]THF): no sharp signals due to low
Na2Te2 (436 mg, 1.5 mmol). After the clear red solution had been
Chem. Eur. J. 2014, 20, 704 – 712
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710
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Full Paper
decanted, the solvent was removed. Recrystallization from THF at
CCDC-945396 (1a), CCDC-945397 (2a), CCDC-961072 (3a), CCDC-
961073 (5a), CCDC-945398 (6a), CCDC-945400 (7a) and CCDC-
945399 ((AdP)4) contain the supplementary crystallographic data
for this paper. These data can be obtained free of charge from The
Cambridge Crystallographic Data Centre via www.ccdc.cam.ac.uk/
data_request/cif.
À408C gave orange crystals of (TrtPTe)3 in an overall yield of 8%.
Data for 5a: 31P NMR (109.37 MHz, [D8]THF): d=117.9 ppm (s,
1J(P,125Te) =À398.7, 2J(P,P)=257.1 Hz); 125Te NMR (85.24 MHz,
1
[D8]THF): d=598.9 ppm (m, J(P,125Te) 396.3 Hz); MS (EI+): only frag-
ments observed: m/z calcd for 243.1 [Trt+]; found: 243.1 [Trt+]; Ten
(n=2, 3, 4, 5, 6); elemental analysis calcd (%) for C73H77O4P3Te3
(5a+4THF): C 58.69, H 5.19; found: C 58.51, H 4.98.
Acknowledgements
Data for 5b: 31P NMR (109.37 MHz, [D8]THF): d=131.8 (d,
1J(P,125Te) =72.2 Hz, 1J(P,P)=189.2 Hz, 2J(P,P)=3.3 Hz), 82.1 ppm (t,
1J(P,P)=187.0 Hz); 125Te NMR (85.24 MHz, [D8]THF): due to the low
yield of 5b, no clear 125Te resonance was observed; MS (EI+): see
data for 5a.
We are grateful to the University of St Andrews, the EPSRC and
NSERC Canada for their financial support.
Keywords: heterocycles · NMR spectroscopy · phosphorus ·
tellurium · X-ray diffraction
Synthesis of [(m-Te-P(Ad)-Te)(tBuN)P(m-NtBu)2P(NtBu)] (6a)
[23]
Complex [tBuN(Te)P(m-NtBu)2P(Te)NtBu)][Li(TMEDA)]2
(500 mg,
[1] H. Hoffmann, G. Schumacher, Tetrahedron Lett. 1967, 8, 2963–2966.
[2] a) G. Hua, J. D. Woollins, Angew. Chem. 2009, 121, 1394–1403; Angew.
Chem. Int. Ed. 2009, 48, 1368–1377; b) G. Hua, J. M. Griffin, S. E. Ash-
brook, A. M. Z. Slawin, J. D. Woollins, Angew. Chem. 2011, 123, 4209–
4212; Angew. Chem. Int. Ed. 2011, 50, 4123–4126; c) G. Hua, A. M. Z.
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1169.
[3] M. Jesberger, T. P. Davis, Synthesis 2003, 1929–1958.
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39, 3740–3749.
[5] T. Chivers, I. Manners, Inorganic Rings and Polymers of the p-Block Ele-
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2009, pp. 256–260.
[6] W.-W. du Mont, T. Severengiz, B. Meyer, Angew. Chem. 1983, 95, 1025–
1026; Angew. Chem. Int. Ed. Engl. 1983, 22, 983–984.
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1087.
[8] S. Grimm, K. Karaghiosoff, P. Mayer, D. Ross, Phosphorus Sulfur Silicon
Relat. Elem. 2001, 169, 51–54.
0.59 mmol) was suspended in toluene (10 mL) and cooled to
À788C. AdPCl2 (140 mg, 0.59 mmol) was dissolved in toluene
(10 mL), maintained at À788C and then added dropwise to the so-
lution of [Li(TMEDA)]2[tBuN(Te)P(m-NtBu)2P(Te)NtBu)] over 15 min by
cannula. The reaction mixture was stirred at that temperature for
2 h and then warmed to RT. After stirring for an additional 1 h, the
precipitate (LiCl) was filtered off, and the solvent removed under
vacuum. The obtained solid was dissolved in n-hexane and main-
tained at À408C overnight. The deep red crystals were filtered off
and dried under vacuum. The resulting filtrate was concentrated
and again placed in the freezer overnight to produce another
batch of crystals (overall yield: 23%). 1H NMR (270.17 MHz, C6D6):
d=1.98 (m, 9H, Ad) 1.82 (s, 9H, tBu), 1.73 (s, 9H, tBu), 1.47 (s, 18H,
tBu), 1.42 ppm (m, 6H, Ad); 31P NMR (109.37 MHz, C6D6): d=89.5 (t,
1J(P,Te) =420 Hz, 2J(P,P)=8.1 Hz), À129.0 ppm (d, 1J(P1,Te)=
1073 Hz,
2J(P1,P2)=8.1 Hz,
2J(P1,P1’)=21 Hz);
125Te NMR
(85.24 MHz,
[D8]toluene):
d=368.5 ppm
(1J(P2,Te)=418 Hz,
3
1J(P1,Te)=1073 Hz, J(P,Te)=29 Hz); MS (CI+): m/z calcd 769.1 [M+
+H], 769.1 [M+ +H]; elemental analysis calcd (%) for
C26H51N4P3Te2: C 40.67, H 6.69, N 7.30; found: C 40.76, H 6.71, N
7.38.
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2469.
[10] N. Nagahora, T. Sasamori, N. Tokitoh, Heteroat. Chem. 2008, 19, 443–
449.
Synthesis of [(m-Te-P(tBu)-Te)(tBuN)P(m-NtBu)2P(NtBu)] (7a)
[11] The higher thermal robustness of the adamantyl (Ad) compared to the
tBu derivative enabled the first structural characterization of a selenium
diimide, RN=Se=NR; a) T. Maaninen, R. Laitinen, T. Chivers, Chem.
Commun. 2002, 2332–2333; For examples of FcLR chemistry, see
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[14] At low temperature, resonances in the 31P NMR spectrum were ob-
served, which indicated the presence of a 1,3-ditellura-2,4,5-triphospho-
lane consistent with an ABM spectrum (ignoring the 125Te-containing
isotopomers). At room temperature, the signals disappeared, which
precluded further characterization. The spin simulation and spectrum of
the compound are displayed in the Supporting Information. The calcu-
lated values of the NMR parameters are comparable to those of
du Mont and Severengiz Te2(tBuP)3 (Ref. [7]). A reinvestigation of Te2-
(tBuP)3 showed three distinct phosphorus signals in the 31P NMR consis-
tent with the suggested cis-structure (Ref. [7]). Similarly, Karaghiosoff
and co-workers reported Te2(CF3P)3 (Ref. [9]).
Procedure as for 6a by using tBuPCl2 (94 mg, 0.59 mmol) and
[23]
[tBuN(Te)P(m-NtBu)2P(Te)NtBu)][Li(TMEDA)]2
(500 mg, 0.59 mmol;
yield: 18%).1H NMR (270.17 MHz, [D8]toluene): d=1.86 (s, 9H, tBu),
2
1.72 (s, 9H, tBu), 1.45 (s, 18H, tBu), 1.40 ppm (d, 9H, PtBu, J(P,H)=
12 Hz); 31P NMR (109.37 MHz, [D8]toluene): d=93.9 (t, 1J(P,Te)=
418 Hz, 2J(P2,P1)=8.1 Hz), À129.6 ppm (d, 1J(P,Te)=1073 Hz,
2J(P1,P2)=8.4 Hz,
2J(P1,P1’)=21 Hz);
125Te NMR
(85.24 MHz,
[D8]toluene): d=423.4 ppm (1J(P2,Te)=416 Hz, 1J(P1,Te)=1073 Hz,
3J(P,Te)=32 Hz); MS (CI+): m/z calcd 691.1 [M+ +H]; found: 691.1
[M+ +H]; elemental analysis calcd (%) for C20H45N4P3Te2: C 34.83, H
6.58, N 8.12; found: C 34.84, H 6.61, N 7.97.
X-ray analysis
X-ray crystal data for compounds 1a, 3a, 5a, 6a and 7a were col-
lected on a Rigaku Mo MM007 (dual port) high-brilliance generator
with Saturn 70 and Mercury CCD detectors, rotating anode/confo-
cal optics and two XStream LT accessories at À180(1)8C. Com-
pound 2a was measured on a Nonius-KappaCCD, equipped with
rotating anode at À738C. All data were collected with graphite-
monochromated MoKa radiation (l=0.71073 ꢁ) and corrected for
Lorentz and polarization effects.
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4589.
[16] All spin simulations were performed by using MestReNova v7.1.1-9649,
Mestrelab Research S.L., 2012.
Chem. Eur. J. 2014, 20, 704 – 712
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[17] Negative signs of the coupling constants result from the iterative fitting
of the spectrum.
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Received: October 3, 2013
[26] Disordered structure and crystallographic data including bond lengths
and angles for 7a are deposited in the Supporting Information.
Published online on December 16, 2013
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