Synthesis, properties, and ligating behavior of the first facultative tritelluroethers, Te(CH2CH2CH2TeR)2 (R = Me or Ph)

Article abstract of DOI:10.1021/om0102495

The first examples of linear tritelluroether ligands, Te(CH₂CH₂CH₂TeR)₂ [L, R = Me (L¹) or Ph (L²)], have been prepared from Na₂Te and RTeCH₂CH₂CH₂Cl and fully characterized spectroscopically and by quanternization with MeI to the corresponding telluronium salts, MeITe(CH₂CH₂CH₂ TeRMeI)₂. A series of metal complexes have been prepared, the metal substrate being chosen to illustrate the ligating modes available to these ligands and to permit comparison with literature data on complexes of Se(CH₂CH₂CH₂SeMe)₂ and MeC-(CH₂TeR)₃. In fac-[Mn(CO)₃(L)]CF₃SO₃ the ligands bind as tridentates facially to the metal center, whereas in [PtCl(L)]PF₆ the ligands occupy three positions on the square-planar metal center. The [{η⁵-C₅Me₅}Rh(L)] (PF₆)₂ contain tridentate L bound to one triangular face of the octahedron. The X-ray crystal structure of [{η⁵-C₅Me₅}Rh(L²)] (PF₆)₂·MeOH shows tridentate telluroether coordination with the ligand adopting the DL configuration, giving a distorted pseudo-octahedral environment at Rh(III). A short contact between one C-H group in one of the phenyl rings and the centroid of the other phenyl ring (2.56 A?) helps to stabilize the adopted configuration. The metal complexes have been characterized by analysis, ES⁺ or FAB mass spectrometry, and IR and multinuclear NMR (¹H, ¹³C{¹H}, ¹²⁵Te) spectroscopy. The invertomers present in coordinated L have been established by the multinuclear NMR studies.

Full text of DOI:10.1021/om0102495

3644
Organometallics 2001, 20, 3644-3649
Articles
Syn th esis, P r op er ties, a n d Liga tin g Beh a vior of th e F ir st
F a cu lta tive Tr itellu r oeth er s, Te(CH2CH2CH2TeR)2
(R ) Me or P h )
Andrew J . Barton, William Levason,* Gillian Reid, and Antony J . Ward
Department of Chemistry, University of Southampton, Southampton SO17 1BJ , U.K.
Received March 26, 2001
The first examples of linear tritelluroether ligands, Te(CH2CH2CH2TeR)2 [L, R ) Me (L1)
or Ph (L2)], have been prepared from Na2Te and RTeCH2CH2CH2Cl and fully characterized
spectroscopically and by quaternization with MeI to the corresponding telluronium salts,
MeITe(CH2CH2CH2TeRMeI)2. A series of metal complexes have been prepared, the metal
substrate being chosen to illustrate the ligating modes available to these ligands and to
permit comparison with literature data on complexes of Se(CH2CH2CH2SeMe)2 and MeC-
(CH2TeR)3. In fac-[Mn(CO)3(L)]CF3SO3 the ligands bind as tridentates facially to the metal
center, whereas in [PtCl(L)]PF6 the ligands occupy three positions on the square-planar metal
center. The [{η5-C5Me5}Rh(L)](PF6)2 contain tridentate L bound to one triangular face of
the octahedron. The X-ray crystal structure of [{η5-C5Me5}Rh(L2)](PF6)2‚MeOH shows
tridentate telluroether coordination with the ligand adopting the DL configuration, giving a
distorted pseudo-octahedral environment at Rh(III). A short contact between one C-H group
in one of the phenyl rings and the centroid of the other phenyl ring (2.56 Å) helps to stabilize
the adopted configuration. The metal complexes have been characterized by analysis, ES+
or FAB mass spectrometry, and IR and multinuclear NMR (1H, 13C{1H}, 125Te) spectroscopy.
The invertomers present in coordinated L have been established by the multinuclear NMR
studies.
In tr od u ction
of the first linear tritelluroethers Te(CH2CH2CH2TeR)2
(R ) Me, L1 or Ph, L2) and a representative range of
transition metal complexes, which allow comparison of
their ligating behavior with the previously reported
tripods4,6-10 and the selenoether analogue Se(CH2CH2-
CH2SeMe)2.11,12
Although the synthesis and coordination chemistry
of tellurium donor ligands has been developing rapidly
in the last 10 or so years, studies are still far more
limited than with sulfur and selenium analogues.1,2
While this is in part due to less effort devoted to Te
ligands, it also reflects the considerably greater prob-
lems in the synthesis of other than the simplest types.
For example, the instability of the Te-H bond in
tellurols (RTeH) makes these useless as synthons, while
the weak Te-C bonds mean that bi- or polydentates
with -TeCH2CH2Te- or cis-TeCHdCHTe- linkages
cannot be made.3 These problems are particularly
pronounced in the synthesis of polydentates or homo-
leptic tellurium macrocycles, where sequential genera-
tion of new Te-C bonds often competes with facile Te-C
bond cleavage in precursors.3 As a result of these
problems, only two tritelluroethers, the tripodal MeC-
(CH2TeR)3 (R ) Me3 or Ph4), the spirocyclic C(CH2-
TePh)4,3 and one macrocycle, 1,5,9-tritelluracyclodode-
cane,5 have been described. We report here the synthesis
Exp er im en ta l Section
All preparations were conducted in good fume hoods under
a dry dinitrogen atmosphere, and ligands and intermediates
were stored under dinitrogen in a freezer. The tellurium
ligands and intermediates have persistent, repulsive odors.
Aqueous waste and used glassware was treated with aqueous
NaOCl for 12 h to remove most of the odor. Tetrahydrofuran
was distilled from sodium benzophenoneketyl before use, while
(5) Takaguchi, Y.; Horn, E.; Furakawa, N. Organometallics 1996,
15, 5112.
(6) Levason, W.; Orchard, S. D.; Reid, G. Chem. Commun. 1999,
1071.
(7) Levason, W.; Orchard, S. D.; Reid, G. Inorg. Chem. 2000, 39,
3853.
(8) Levason, W.; Orchard, S. D.; Reid, G.; Street, J . M. J . Chem.
Soc., Dalton Trans. 2000, 2537.
(9) Levason, W.; Orchard, S. D.; Reid, G. Chem. Commun. 1999, 823.
(10) Barton, A. J .; Connolly, J .; Levason, W.; Media-J alon, A.;
Orchard, S. D.; Reid, G. Polyhedron 2000, 19, 1373.
(11) Hope, E. G.; Levason, W.; Murray, S. G.; Marshall, G. L. J .
Chem. Soc., Dalton Trans. 1985, 2185.
(12) Gulliver, D. J .; Hope, E. G.; Levason, W.; Murray, S. G.; Potter,
D. M.; Marshall, G. L. J . Chem. Soc., Perkin Trans. 2 1984, 429.
(1) Hope, E. G.; Levason, W. Coord. Chem. Rev. 1993, 122, 109.
(2) Singh, A. K.; Sharma, S. Coord. Chem. Rev. 2000, 209, 49.
(3) Kemmitt, T.; Levason, W. Organometallics 1988, 7, 78. Kemmitt,
T. Ph.D. Thesis, University of Southampton, 1988.
(4) Connolly, J .; Genge, A. R. J .; Levason, W.; Orchard, S. D.; Pope,
S. J . A.; Reid, G. J . Chem. Soc., Dalton Trans. 1999, 2343.
10.1021/om0102495 CCC: $20.00 © 2001 American Chemical Society
Publication on Web 07/18/2001

First Facultative Tritelluroethers
Organometallics, Vol. 20, No. 17, 2001 3645
other solvents were obtained commercially and used as sup-
plied. Tellurium pieces were obtained from Aldrich and ground
to a powder immediately before use.
eluting with diethyl ether-hexane (1:10) to produce a red oil.
Yield: 4.08 g, 62%. EI+ MS: m/z 624, calcd for C18H22130Te3
628. H NMR (CDCl3): 7.89 (m) [2H], 7.37 (m) [H], 7.32 (m)
1
[2H], 3.24 (t, 3J ) 7.4 Hz) [2H] CH2TePh, 3.04 (t, 3J ) 7.4 Hz)
[2H] CH2Te, 2.33 (m) [2H] CH2. 13C{1H} (CDCl3): 138.5, 129.4,
127.8, 112.4 Ph, 35.4 CH2, 11.0 (1J Te-C ) 158 Hz), 6.9 (1J Te-C
) 176 Hz) CH2Te. 125Te{1H} (neat): 465, 123.
1H NMR spectra were obtained on a Bruker AC300 and
13C{1H} NMR on a Bruker AC300 or DPX400 and referenced
via residual proton signals in the deuterated solvents to TMS.
125Te, 55Mn, and 195Pt NMR spectra were obtained on a Bruker
DPX400 and are referenced to (neat) Me2Te, saturated aqueous
KMnO4, and aqueous [PtCl6]2-, respectively. Microanalyses
were obtained from the University of Strathclyde Analytical
Laboratory. Other measurements were made as in previous
reports from these laboratories.6-8,10
The tris(methiodide) {MeIPhTe(CH2)3}2TeMeI was made by
stirring the ligand (0.31 g, 0.5 mmol) in excess MeI (3 cm3) in
acetone (20 cm3) for 1 h. The solution was concentrated to 5
cm3 and cooled, and the white crystals were filtered off, rinsed
with diethyl ether, and dried. Yield: 0.45 g, 85%. Anal. Calcd
for C21H31I3Te3: C, 24.1; H, 3.0. Found: C, 23.7, 3.7. 125Te NMR
(Me2CO): 484, 602.
1. P h Te(CH2)3OH. A freshly prepared solution of PhTeLi
(0.05 mol) in thf3 was frozen in liquid nitrogen and 3-bro-
mopropan-1-ol (6.96 g, 0.05 mol) added. The mixture was
allowed to thaw, warmed to room temperature, and stirred
for 2 h. Water (100 cm3) was added, and the organic phase
separated and dried over magnesium sulfate. The drying agent
was filtered off and the solvent removed in vacuo to leave a
red oil. Yield: 11.5 g, 84%. APCI MS (MeCN): m/z 266, calcd
for C9H12O130Te 266. 1H NMR (CDCl3): 7.72 (m) [2H], 7.18 (m)
6. Te(CH2CH2CH2TeMe)2, L1, was made similarly to 5,
from Na (0.52 g, 23 mmol), Te (1.47 g, 11.5 mmol) in liquid
ammonia (200 cm3), and MeTe(CH2)3Cl (5.0 g, 23 mmol) in thf
(75 cm3). Purification by chromatography with diethyl ether-
hexane (1:10) gave an orange oil. Yield: 3.2 g, 56%. EI+ MS:
1
m/z 498, calcd for C8H18130Te3 504. H NMR (CDCl3): 2.70 (t,
3J ) 6.5 Hz) [2H] CH2Te, 2.68 (t, 3J ) 6.5 Hz) [2H] CH2Te,
2.12 (m) [2H] CH2, 1.92 (s) [3H] Me. 13C{1H} (CDCl3): 33.9
CH2, 5.4 (1J Te-C ) 145 Hz), 4.9 (1J Te-C ) 140 Hz) CH2Te, -22.0
(1J Te-C ) 160 Hz) MeTe. 125Te{1H} (neat): 116.8, 154.4.
The tris(methiodide) was made as for 5: white crystals, 39%.
Anal. Calcd for C11H27I3Te3 C, 14.3; H, 3.0. Found: C, 14.7;
H, 2.9. 125Te NMR (Me2CO): 487, 522.
3
3
[3H], 3.64 (m, J ) 3.7 Hz) [2H] CH2O, 2.96 (t, J ) 7.4 Hz)
[2H] CH2Te, 2.91 (s) [1H] OH, 2.03 (m) CH2. 13C{1H} (CDCl3):
138.3, 129.4, 127.3, 112.1 Ph, 63.8 CH2OH, 34.4 CH2, 3.5
(1J Te-C ) 156 Hz) CH2Te. 125Te{1H} (neat): 464.
2. P h Te(CH2)3Cl. To a solution of PPh3 (2.09 g, 7.96 mmol)
and PhTe(CH2)3OH (2.0 g, 7.56 mmol) in MeCN (20 cm3) was
added CCl4 (1 cm3) and the mixture refluxed for 30 min. The
solvent was removed in vacuo, and the residue extracted with
n-hexane. Removal of the hexane in vacuo left an orange oil.
Yield: 1.48 g, 68%. APCI MS (MeCN): m/z 284, calcd for
7. [Rh (η5-C5Me5)(L1)][P F 6]2. A mixture of L1 (0.15 g, 0.3
mmol), TlPF6 (0.21 g, 0.6 mmol), and [{Rh(η5-C5Me5)Cl2}2] (0.09
g, 0.15 mmol) was refluxed together in MeOH (40 cm3) for 18
h, resulting in a white precipitate (TlCl) and a yellow solution.
The solution was filtered through Celite and the volume
reduced to 2 cm3. Addition of diethyl ether gave an orange
solid. Yield: 0.27 g, 87%. The complex was analytically pure
but could be recrystallized from acetone/diethyl ether. Anal.
Calcd for C18H33F12P2RhTe3: C, 21.1; H, 3.2. Found: C, 20.5;
H, 3.1. ES+ MS: m/z 368, calcd for C18H33Rh130Te3 371. 1H
NMR (acetone-d6): 2.06 (m) CH2, 2.10 (s) C5Me5, 2.39 (d) 2.45
(d), 2.52 (d), 2.59 (d) Me, 3.1-3.4 (m) CH2Te. 13C{1H} (acetone-
d6): 104.2, 103.7 (C5Me5), 33.3 CH2, 11.4, 11.2, 10.5, 6.3
(CH2Te), 9.6, 9.4, 9.1 (C5Me5), -7.5, -8.2, -10.4, -11.0 (MeTe).
125Te{1H} (acetone-d6): 209.4 (d) (1J Rh-Te ) 80 Hz), 235.5 (br,
4 lines?), 263.7 (d) (1J Rh-Te ) 89 Hz), 264.1 (1J Rh-Te ) 95 Hz).
8. [Rh (η5-C5Me5)(L2)][P F 6]2. A mixture of L2 (0.19 g, 0.3
mmol), TlPF6 (0.21 g, 0.6 mmol), and [{Rh(η5-C5Me5)Cl2}2] (0.09
g, 0.15 mmol) was refluxed together in MeOH (40 cm3) for 18
h, resulting in a white precipitate (TlCl) and a yellow solution.
The solution was filtered through Celite, and the volume
reduced to 2 cm3. Addition of diethyl ether gave an orange
solid. Yield: 0.22 g, 64%. The complex was analytically pure
but could be recrystallized from acetone/diethyl ether. Anal.
Calcd for C28H37F12P2RhTe3: C, 29.3; H, 3.3. Found: C, 29.5;
1
C9H1235Cl130Te 284. H NMR (CDCl3): 7.86 (m) [2H], 7.40 (m)
3
[H], 7.31 (m) [2H], 3.65 (m, J ) 6.5 Hz) [2H] CH2Cl, 3.09 (t,
3J ) 7.4 Hz) [2H] CH2Te, 2.28 (m) [2H] CH2. 13C{1H} (CDCl3):
138.7, 129.6, 128.0, 111.8 Ph, 47.6 CH2Cl, 34.6 CH2, 5.1 (1J Te-C
) 162 Hz) CH2Te. 125Te{1H} (neat): 470.
3. MeTe(CH2)3OH. A solution of MeTeLi in thf3 (0.05 mol)
was frozen with liquid nitrogen, 3-chloropropan-1-ol (4.73 g,
0.05 mol) was injected in, and the mixture was allowed to
warm to room temperature and stirred for 2 h. Water (100
cm3) was added, the organic phase separated, and the water
re-extracted with diethyl ether (3 × 50 cm3). The combined
organic phases were dried over magnesium sulfate. Filtration
and removal of the solvent in vacuo left an orange oil. Yield:
8.1 g, 80%. APCI MS (MeCN): m/z 205, calcd for C4H10O130Te
1
3
205. H NMR (CDCl3): 4.09 (br) [H] OH, 3.65 (t, J ) 6.5 Hz)
[2H] CH2O, 2.60 (t, 3J ) 7.4 Hz) CH2Te, 2.00 (m) [2H] CH2,
1.90 (s) [3H] Me. 13C{1H} (CDCl3): 63.7 CH2OH, 34.5 CH2,
-1.6 (1J Te-C ) 150 Hz) CH2Te, -22.7 (1J Te-C ) 160 Hz) TeMe.
125Te{1H} (neat): 113.
4. MeTe(CH2)3Cl. A mixture of PPh3 (6.56 g, 25 mmol),
PhTe(CH2)3OH (4.0 g, 20 mmol), and CCl4 (2 cm3) was refluxed
in MeCN (20 cm3) for 30 min. The solvent was removed in
vacuo and the residue extracted with n-hexane. Removal of
the solvent in vacuo gave an orange oil. Yield: 2.64 g, 60%.
1
H, 3.3%. ES+ MS: m/z 430, calcd for C18H33Rh130Te3 433. H
NMR (acetone-d6): 1.85 (m) CH2, 2.08 (s) C5Me5, 3.1-3.6 (m)
CH2Te, 7.2-7.7 (m) Ph. 13C{1H} (acetone-d6): 134-129 (br)
Ph, 100.7 C5Me5, 33.7 CH2, 8.4 C5Me5, 5.0, 4.6, 3.0 CH2Te.
125Te{1H} (acetone-d6): 468.5 (d) (1J Rh-Te ) 80 Hz), 455.1 (d)
(1J Rh-Te ) 90 Hz), 384.5 (d) (1J Rh-Te ) 93 Hz), 218.1 (d) (1J Rh-Te
) 98 Hz).
1
APCI MS (MeCN): m/z 222, calcd for C4H1035Cl130Te 222. H
3
NMR (CDCl3): 3.44 (t 3J ) 6.5 Hz) [2H] CH2Cl, 2.53(t, J )
3
7.0 Hz) [2H] CH2Te, 1.93 (m, J ) 7.0 Hz) [2H] CH2, 1.74 (s)
[3H] Me. 13C{1H} (CDCl3): 46.3 CH2Cl, 34.3 CH2, -0.4 (1J Te-C
) 157 Hz) CH2Te, -21.8 (1J Te-C ) 160 Hz) TeMe. 125Te{1H}
(neat): 112.5.
9. fa c-[Mn (CO)3(L1)]CF 3SO3. The compounds [Mn(CO)5Cl]
(0.05 g, 0.19 mmol) and AgCF3SO3 (0.05 g, 0.19 mmol) were
stirred together in acetone (40 cm3) at 60 °C for 1 h. The
reaction was monitored by IR spectroscopy to check formation
of [Mn(CO)3(acetone)3]+ was complete, and then the precipi-
tated AgCl was filtered off. L1 (0.1 g, 0.19 mmol) was added
and the solution refluxed for 0.5 h and then stirred at room
temperature for 18 h. The solution was concentrated to 2 cm3
and diethyl ether added to precipitate an orange solid, which
was dried in vacuo. Yield: 0.08 g, 57%. Anal. Calcd for
5. Te(CH2CH2CH2TeP h )2, L2. Sodium (0.41 g, 17.7 mmol)
and tellurium powder (1.13 g, 8.9 mmol) were dissolved
sequentially in liquid ammonia (200 cm3), and PhTe(CH2)3Cl
(5.0 g, 17.7 mmol) in thf (75 cm3) was added at -78 °C. The
mixture was stirred at this temperature for 6 h, allowed to
warm to room temperature, and then stirred for 16 h. The
residue was treated with water (50 cm3) and extracted with
diethyl ether (3 × 50 cm3), and the organic phase was dried
over magnesium sulfate. The solvent was removed in vacuo
and the product purified by flash chromatography on silica,
C
12H18F3MnO6STe3: C, 18.4; H, 2.3. Found: C, 18.8; H, 2.7%.
ES+ MS: m/z 637, calcd for C11H18O3Mn130Te3 637. IR cm-1

3646 Organometallics, Vol. 20, No. 17, 2001
Barton et al.
(acetone solution): 2014, 1936. 1H NMR (CDCl3): 2.9-3.2 (m)
CH2Te, 2.4, 2.36, 2.32, 2.26 (Me), 2.02 (m) CH2. 13C{1H}
(CDCl3): 217-220 (br) CO, 30.8 CH2, 10.8, 8.6 CH2Te,
-8.5-9.3 MeTe. 125Te{1H} (acetone-d6): 119.7, 128.5, 168.5,
169.0, 170.0 (sh) 55Mn (300 K, acetone-d6): -1338 (w1/2 900 Hz),
-1362 (w).
Ta ble 1. Selected Bon d Len gth s (Å) a n d An gles
(d eg) for [Rh (η5-C5Me5)(L2)]2+
atom
atom
distance
Rh(1)
Rh(1)
Rh(1)
Te(1)
Te(1)
Te(2)
Te(2)
Te(3)
Te(3)
Te(1)
Te(2)
Te(3)
C(1)
C(7)
C(9)
2.6177(7)
2.6016(7)
2.6015(7)
2.118(7)
2.152(7)
2.155(7)
2.155(7)
2.145(7)
2.110(6)
2.207(6)-2.236(7)
10. fa c-[Mn (CO)3(L2)]CF 3SO3 was made similarly to 9
using [Mn(CO)5Br] (0.1 g, 0.35 mmol), AgCF3SO3 (0.1 g, 0.35
mmol), and L2 (0.22 g, 0.35 mmol). The orange solid was
isolated in 0.19 g, 59% yield. Anal. Calcd for C22H22F3MnO6-
STe3: C, 28.8; H, 2.4. Found: C, 28.6; H, 2.2. ES+ MS: m/z
761, calcd for C21H22O3Mn130Te3 761. IR cm-1 (acetone solu-
C(10)
C(12)
C(13)
Rh-C in η5-C5Me5
1
tion): 2017, 1940. H NMR (CDCl3): 7.7-7.3 (m) Ph, 2.9-3.6
(br) CH2Te, 2.0 (br) CH2. 13C{1H} (CDCl3): 220-222 (br) CO,
137-130, 112.7 Ph, 30.8 CH2, 2.0, 1.1 CH2Te. 125Te{1H}
(CH2Cl2/CDCl3): 417.5, 400, 362, 132.5, 107. 55Mn (acetone-
d6): -1218 (w1/2 1100 Hz), -1254 (2600 Hz).
atom
atom
atom
angle
Te(1)
Te(1)
Te(2)
Rh(1)
Rh(1)
Rh(1)
Te(2)
Te(3)
Te(3)
91.87(2)
92.56(2)
89.70(2)
11. fa c-[Mo(CO)3(L1)]. [Mo(CO)6] (0.2 g, 0.76 mmol) was
refluxed in MeCN (50 cm3) under argon for 16 h to give [Mo-
(CO)3(MeCN)3]. The ligand L1 (0.42 g, 0.76 mmol) was added,
and the mixture was stirred for a further 16 h, when an IR
spectrum of the solution showed the absence of [Mo(CO)3-
(MeCN)3]. The solvent was removed in vacuo and the residue
extracted with CH2Cl2 (20 cm3) and filtered through Celite.
Concentration of the filtrate to 2 cm3 and addition of di-
ethyl ether gave a brown solid, which was washed with di-
ethyl ether and dried in vacuo. Yield: 0.28 g, 56%. Anal. Calcd
for C11H18MoO3Te3: C, 19.5; H, 2.7. Found: C, 19.6; H, 2.7%.
IR cm-1 (CH2Cl2 solution): 1926, 1827. 1H NMR (CDCl3):
2.6 (m) CH2Te, 2.1 (m) CH2, 1.83 (s), 1.85 (s), 1.86 (s), 1.87 (s)
Me.
Ta ble 2. Cr ysta llogr a p h ic P a r a m eter s for
[Rh (η5-C5Me5){(P h Te(CH2)3)2Te}](P F 6)2‚MeOH
formula
C29H41F12OP2RhTe3
1181.28
M
cryst syst
space group
monoclinic
P21/ c
a/Å
b/Å
c/Å
14.5440(2)
15.4506(2)
16.5224(3)
103.5441(9)
3609.55(9)
4
â/deg
U/Å3
Z
T/K
150
µ(Mo KR)/cm-1
total no. of reflns measured
no. of unique obsd reflns
no. of obsd reflns
with [I > 3σ(I)]
R
30.24
27472 (Rint ) 0.055)
7628
12. [P tCl(L1)]P F 6. PtCl2 (0.15 g, 0.56 mmol) was dissolved
in refluxing MeCN (30 cm3) to produce a yellow solution. TlPF6
(0.2 g, 0.56 mmol) and L1 (0.28 g, 0.56 mmol) were added, and
the mixture was stirred at room temperature for 16 h. The
white TlCl was filtered off, the orange solution was concen-
trated to small volume, and diethyl ether (10 cm3) was added
slowly to precipitate an orange solid, which was collected and
dried in vacuo. Yield: 0.41 g, 84%. The complex decomposes
slowly in solution, but could be quickly recrystallized by
dissolution in MeCN, filtering, and reprecipitation with diethyl
ether. Anal. Calcd for C8H18ClF6PPtTe3: C, 11.0; H, 2.1.
Found: C, 11.3; H, 1.6. ES+ MS: m/z 729, calcd for
C8H1835Cl195Pt130Te3 734. 1H NMR (CD3CN): 2.1-2.2 (m) CH2,
2.31 (s), 2.26 (s), 2.27 (s) Me, 2.4-3.0 (m) CH2Te. 195Pt{1H}
NMR (CD3CN): -3770, -3825. 125Te{1H} NMR (CD3CN):
183.5 (1J Te-Pt ) 296 Hz), 194 (1J Te-Pt ) 308 Hz), 355.5 (1J Te-Pt
) 1400 Hz), 355 (1J Te-Pt ) 1550 Hz).
5149
0.037
0.045
Rw
deg intervals with 10 s exposure. The data were corrected by
SORTAV,13 and the structure was solved using heavy atom
methods and refined by iterative cycles of full-matrix least-
squares refinement.14,15 During refinement one solvent MeOH
molecule was identified in the asymmetric unit. All non-H
atoms were refined anisotropically, and H atoms were included
in fixed, calculated positions, except for the hydroxyl H atom
of the MeOH, which was not located and was therefore omitted
from the final structure factor calculation. Some of the F atoms
-
of the PF6 anions show slightly high thermal parameters,
13. [P tCl(L2)]P F 6 was made similarly to 12 from PtCl2 (0.1
g, 0.36 mmol), TlPF6 (0.13 g, 0.36 mmol), and Te((CH2)3TePh)2
indicative of some disorder; however attempts to split their
occupancies were not successful.
(0.24 g, 0.36 mmol). Yield: 0.23 g, 64%. Anal. Calcd for C18H22
ClF6PPtTe3: C, 21.7; H, 2.2. Found: C, 21.9; H, 2.3. ES+ MS:
m/z 852, calcd for
18H2235Cl195Pt130Te3 858. 1H NMR
-
Resu lts a n d Discu ssion
C
(CD3CN): 2.3-3.2 (m) CH2, 7.3-8.0 (m) Ph. 195Pt NMR
(CD3CN): -3833, -3898. 125Te (CD3CN): 374 (1J Te-Pt ) 1225
Hz), 373 (1J Te-Pt ) 1200 Hz), 415.5 (1J Te-Pt ) 485 Hz), 433
(1J Te-Pt ) 486 Hz).
Tr itellu r oeth er s. The tripodal ligands MeC(CH2-
TeR)3 (R ) Me or Ph) contain only one Te environment
and are made in “one-pot” reactions from (excess) RTeLi
and MeC(CH2Br)3 in tetrahydrofuran.3,4 However the
linear tritelluroethers Te(CH2CH2CH2TeR)2 require
sequential introduction of the central -CH2TeCH2- and
terminal RTeCH2- groups and illustrate the prob-
lems outlined in the Introduction. The triselenoether Se-
(CH2CH2CH2SeMe)2 is readily made by the routes
14. [Rh Cl3(L2)]. To a solution of RhCl3‚3H2O (0.1 g, 0.41
mmol) in ethanol (20 cm3) was added the ligand L2 (0.25 g,
0.41 mmol) in ethanol (10 cm3) and the mixture stirred at room
temperature for 16 h. The product precipitated during this
time as an orange-brown powder, which was washed with
ethanol and dried in vacuo. Yield: 0.245 g, 72%. Anal. Calcd
for C18H22Cl3RhTe3: C, 24.0; H, 2.45. Found: C, 24.3; H, 2.3.
ES+ MS (MeCN): m/z 838, calcd for C18H2235Cl3Rh130Te3 836.
X-r a y Cr ysta l Str u ctu r e of [Rh (η5-C5Me5)(L2)](P F 6)2‚
MeOH. Orange rhomboid crystals were obtained from a
methanol solution of the complex by vapor diffusion of diethyl
ether. Crystallographic parameters are presented in Table 2.
Data collection used an Enraf Nonius Kappa CCD diffracto-
meter operating at 50 kV, 60 mA, with images collected at 1
(13) Blessing, R. H. Acta Crystallogr., Sect. A 1995, 51, 33; J . Appl.
Crystallogr. 1997, 30, 421
(14) Beurskens, P. T.; Admiraal, G.;. Beurskens, G.;. Bosman, W.
P.; Garcia-Granda, S.; Gould, R. O.; Smits, J . M. M.; Smykalla, C.
PATTY, The DIRDIF Program System; Technical Report of the
Crystallography Laboratory; University of Nijmegen, The Netherlands,
1992.
(15) TeXsan: Crystal Structure Analysis Package; Molecular Struc-
ture Corporation: TX, 1995.

First Facultative Tritelluroethers
Organometallics, Vol. 20, No. 17, 2001 3647
Sch em e 1
Sch em e 2
shown in Scheme 1,11 and some years ago the same
routes were explored to prepare Te(CH2CH2CH2TeMe)2.3
These were unsuccessful: reaction of MeTe(CH2)3OTs
with Na2Te in alcohol or thf resulted rapid deposition
of elemental tellurium and formation of Me2Te2 (identi-
fied by 125Te NMR). The reaction of Te(CH2CH2CH2-
OTs)2 with LiTeMe in thf similarly failed.3 Attempts to
prepare MeTe(CH2)3Cl from the corresponding alcohol
by reaction with SOCl2 or MeTe(CH2)3Br using PBr3
failed due to halogenation at tellurium as well as
replacement of the hydroxyl function. The new, suc-
cessful route depends on the chlorination of RTe(CH2)3-
OH with PPh3/CCl416 to RTe(CH2)3Cl, which then reacts
with Na2Te in liquid ammonia to give Te(CH2CH2CH2-
TeR)2 (Scheme 2). After purification by flash column
chromatography, the tritelluroethers were obtained as
orange oils in good yield. In contrast to the thio- and
selenoether analogues, but like RTe(CH2)3TeR,3 the new
tritelluroethers are moderately air-sensitive and convert
into insoluble white oily telluroxide materials on expo-
sure to air. The new ligands showed parent ions with
the correct isotope patterns in the EI+ mass spectra, and
their structures were confirmed by a combination of 1H,
13C{1H}, and 125Te NMR (Experimental Section). The
125Te chemical shifts are very characterstic of the
substituents, and changes as remote as the γ-carbon are
reflected in the shifts.17 Reaction with excess MeI
quaternized all three tellurium centers in each ligand
to form MeITe(CH2CH2CH2TeMeRI)2, identified by analy-
sis and by the large high-frequency shifts in the 125Te
NMR spectra.3
A series of complexes of both ligands was prepared,
the metal systems being chosen to permit direct com-
parison with literature complexes of MeC(CH2TeR)3 or
Se(CH2CH2CH2SeMe)2 (complexes of Se(CH2CH2CH2-
SePh)2 have not been reported1).
[Rh (η5-C5Me5)(L)][P F 6]2. The reaction of RhCl3‚
3H2O with L2 in EtOH gave [RhCl3(L2)], but unfortu-
nately, like [RhCl3{MeC(CH2TeMe)3}],18 this complex
proved to be poorly soluble in organic solvents and
unsuitable for NMR studies. However the reaction of
[{(η5-C5Me5)RhCl2}2], TlPF6, and either L1 or L2 gave
good yields of orange [(η5-C5Me5)Rh(L)](PF6)2, which
were readily soluble in chlorocarbons. Since [(η5-C5Me5)-
Rh(L)](PF6)2 (L ) MeC(CH2SeMe)3, MeC(CH2TeMe)3,
F igu r e 1. View of the structure of [Rh(η5-C5Me5)(L2)]2+
with numbering scheme adopted. Ellipsoids are drawn at
the 40% probability level. The dashed line illustrates the
weak interaction between H(18) and the centroid of the
phenyl ring involving C(1)-C(6).
Sch em e 3
and MeC(CH2TePh)3) have been characterized recently,8
these C5Me5 derivatives are ideal substrates for com-
parison of the ligand properties. Orange crystals of [Rh-
(η5-C5Me5)(L2)](PF6)2‚MeOH were obtained by vapor
diffusion of diethyl ether into a methanol solution of the
complex. The structure shows (Figure 1, Table 1) the
cation adopting a pseudo-octahedral geometry with L2
functioning as a facially coordinated tridentate ligand
and adopting the DL form, with one Ph group pointing
toward the C5Me5 ring and the other pointing away. The
Rh-Te and Rh-C distances are comparable with those
in related complexes.8 This arrangement is further
stabilized by an interaction between H(18) on C(14) and
the centroid of the other phenyl ring, H(18)‚‚‚centroid
) 2.54 Å. This results in the two phenyl rings on the
termini of the tritelluroether lying at approximately 90°
to each other. For a fac-coordinated tridentate L (L )
L1 or L2), three invertomers are possible by symmetry
(Scheme 3), meso-1, meso-2, and DL forms for each of
the two orientations of the lone pair on the central Te,
although it is possible that some may not be present in
significant amounts. The effect of the different orienta-
tions of the central Te free lone pair may not be
sufficient to cause resolvable differences in the NMR
shifts, and in fac-octahedral complexes of Se(CH2CH2-
CH2SeMe)2 only three invertomers were observed.11
Since pyramidal inversion is a high-energy process in
most metal-coordinated telluroethers, the individual
invertomers are expected to be observable in the NMR
(16) Appel, R. Angew. Chem., Int. Ed. Engl. 1975, 14, 801.
(17) O’Brien, D. H.; Dereu, N.; Huang, C. K.; Irgolic, K. J .; Knapp,
F. F., J r. Organometallics 1983, 2, 305.
(18) Levason, W.; Orchard, S. D.; Reid, G. Unpublished work, 1998.

3648 Organometallics, Vol. 20, No. 17, 2001
Barton et al.
spectra. The complexity of the 1H and 13C NMR spectra
means that assignment of resonances to individual in-
vertomers is often not possible, but usually the number
of invertomers present in significant amounts can be
deduced. For [(η5-C5Me5)Rh(L1)]2+ the 1H NMR data
show three δ(TeMe) doublets (3J Rh-H 6 Hz) of ap-
proximately equal intensity and a fourth much weaker
doublet, which is consistent with one meso and the DL
as major forms and a second meso as the minor
component. The 13C{1H} and 125Te NMR data (Experi-
mental Section) are consistent with this interpretation.
For [(η5-C5Me5)Rh(L2)](PF6)2 the spectra are simpler,
consistent with one major invertomer with equivalent
PhTe- groups, almost certainly the meso-1 form, and
two minor doublets presumably due to the DL inver-
tomer. Steric effects should make the bulky Ph groups
avoid the Rh(η5-C5Me5) moiety, destabilizing the other
invertomers. However, in the solid state the close
contact between a C-H from one phenyl ring and the
centroid of the other phenyl ring serves to stabilize the
DL form; see above.
[Mo(CO)3(L)]. Substituted group 6 carbonyls are
often chosen as metal substrates upon which to explore
the coordination properties of new ligands. The reaction
of [Mo(CO)3(MeCN)3]19 with L1 in MeCN gave brown
[Mo(CO)3(L1)], but all attempts to isolate the corre-
sponding complex of L2 failed. The [Mo(CO)3(L1)] was
identified as the expected fac isomer from the presence
of two ν(CO) vibrations (CH2Cl2 solution 1926, 1827
cm-1) in the IR spectrum (theory A1 + E), which can be
compared with the corresponding modes in fac-[Mo-
(CO)3{MeC(CH2TeMe)3}] (1930, 1820 cm-1).10 Previous
studies showed that [M(CO)3{MeC(CH2EMe)3}] (M )
Cr, Mo, or W; E ) S, Se, or Te) were unstable in solution,
decomposing to [M(CO)4(η2-MeC(CH2EMe)3}] and other
products, and the instability is greater with [Mo(CO)3-
(L1)]. Although we obtained a 1H NMR spectrum that
showed the presence of several invertomers, attempts
to obtain 125Te or 95Mo NMR data failed even at low
temperature due to this decomposition.
the MeC(CH2TeR)3. For a facially coordinated linear
tridentate, the possible invertomers (Scheme 3) are not
detectable in the IR data, but are easily observed in the
NMR spectra. The 1H and 13C{1H} NMR spectra are
complex and consistent with the presence of several
invertomers, but the number of isomers is best estab-
lished from the 55Mn and 125Te NMR spectra, which are
much clearer. The 55Mn NMR spectrum of [Mn(CO)3-
(L1)]+ shows a strong resonance at δ -1338 and a
weaker feature at -1362 (ratio ca. 10:1), and there are
corresponding features at 119.7, 128.5 (major), (CH2-
TeCH2) 168.5, 169.0 (major), and 170.0 (TeMe) in the
125Te NMR spectrum, which indicate that two inver-
tomers are present, the DL (minor) and one meso (major),
almost certainly meso-1, since meso-2 where the -TeR
are close to the CO groups is likely to be less favored.
For the [Mn(CO)3(L2)]+ two invertomers are also present
[δ(55Mn) -1218, -1254; δ(125Te) 417.5, 400, 362 (PhTe),
132.5, 107 (CH2TeCH2)] but in approximately equal
amounts, again tentatively assigned as DL and meso-1.
We can also compare the 55Mn NMR shifts with those
in the complexes of Se(CH2CH2CH2SeMe)2 (-560), MeC-
(CH2TeMe)3 (-1509), and MeC(CH2TePh)3 (-1320). The
low-frequency shifts in the telluroether complexes are
again evidence of high electron density on the metal.20
[P tCl(L)]P F 6. The reaction of either tritelluroether
with PtCl2 in MeCN gave very poorly soluble brown
solids which were unsuited to NMR study, but in the
presence of 1 equiv of TlPF6, the products were orange
[PtCl(L)]PF6. Both complexes show multiplet peaks with
the correct isotope structure in the ES+ mass spectra
consistent with [PtCl(L)]+. The 195Pt NMR spectra of
both complexes contain two broad resonances in the
range δ -3600 to -4000, which can be compared with
ca. -3000 to - 3300 for PtIICl2Te2 and ca. -4700 to
-5000 for PtIITe4 donor sets.7,21,22 Hence the present
complexes are readily identified as containing planar
PtIITe3Cl entities. The broad lines and the absence of
125Te couplings are attributable to the onset of pyrami-
dal inversion processes and are also observed in [Pt-
(ditelluroether)2]2+ complexes,22 where the high trans
effect of trans-RTe-Pt-TeR arrangements lowers the
inversion barrier. The 125Te NMR spectra are sharper
and show clear 195Pt-125Te couplings with two RTe
resonances in each complex attributable to two meso
arrangements at the planar Pt(II) center. The 125Te
NMR spectrum of [PtCl(L1)]+ shows some other very
weak resonances which may be due to the DL form, but
these were too weak to observe any 195Pt coupling, and
alternatively may be impurities. On standing for some
hours, CH2Cl2 solutions of both complexes darken and
now exhibit 195Pt resonances with δ < -5000 and 125Te
resonances without any 195Pt couplings. We have not
characterized these products, but it is likely they result
from C-Te bond fission.
[Mn (CO)3(L)](CF 3SO3). In view of the instability of
the molybdenum complexes, we turned our attention to
the more stable fac-[Mn(CO)3(ligand)]+, for which ex-
amples with ligand ) MeC(CH2TeMe)3, MeC(CH2-
TePh)3, Se(CH2CH2CH2SeMe)2, and S(CH2CH2SMe)2
have been characterized recently.4 The orange [Mn-
(CO)3(L)](CF3SO3) containing L1 or L2 were made in
good yield from [Mn(CO)3(Me2CO)3](CF3SO3) in acetone.
The cations were confirmed as fac isomers from the
presence of two ν(CO) stretches in their solution IR
spectra (for L1 2014, 1936, L2 2017,1940 cm-1). These
values may be compared with corresponding data on
[Mn(CO)3(ligand)]+ where ligand ) Se(CH2CH2CH2-
SeMe) 2029, 1945 cm-1, MeC(CH2TeMe)3 2023, 1947
cm-1, MeC(CH2TePh)3 2028, 1959 cm-1, and S(CH2CH2-
SMe)2 2047, 1968 cm-1 4
.
The shift of the two ν(CO)
Con clu sion s. The spectroscopic data described above
show that like MeC(CH2TeR)3 the linear tritelluroethers
are strong σ-donors toward metal carbonyl fragments.
The ligands also form complexes with medium oxidation
state metals such as Rh(III) or Pt(II), although in the
platinum case decomposition occurs in solution over
modes to low-frequency S(CH2CH2SMe)2 f Se(CH2CH2-
CH2SeMe)2 f MeC(CH2TeMe)3 f L2 f L1 is evidence
for the increased ligand f Mn donation observed as
group 16 is descended20 and suggests that L1 and L2
are similar, possibly even slightly better σ-donors than
(19) Kubas, G. J . Inorg. Synth. 1990, 27, 4.
(20) Levason, W.; Orchard, S. D.; Reid, G. Organometallics 1999,
18, 1275.
(21) Kemmitt, T.; Levason. W. Inorg. Chem. 1990, 29, 731.
(22) Levason, W.; Orchard, S. D.; Reid, G.; Tolhurst, V.-A. J . Chem.
Soc., Dalton Trans. 1999, 2071.

First Facultative Tritelluroethers
Organometallics, Vol. 20, No. 17, 2001 3649
several hours. The new tritelluroethers do not have the
same steric limitations of the tripodal type and should
support a wider range of metal center geometries. The
synthetic route developed to RTe(CH2)3Cl is expected
to be sufficiently versatile to allow the preparation of
tetradentate and macrocyclic telluroethers, and this is
currently under investigation.
plc for loans of platinum metal salts, and Professor M.
B. Hursthouse for access to the Kappa CCD diffracto-
meter.
Su p p or tin g In for m a tion Ava ila ble: X-ray crystallo-
graphic files in CIF and PDF format. The material is available
free of charge via the Internet at http://pubs.acs.org.
Ack n ow led gm en t. We thank the EPSRC for post-
doctoral support (A.J .B. and A.J .W), J ohnson Matthey
OM0102495