Synthesis, spectroscopic and structural characterisation of complexes of the new ditelluroether 1,2-bis(methyltelluromethyl)benzene, o-C6H4(CH2TeMe)2. X-ray structures of [Mn(CO)3Cl{o-C6H4(CH2TeMe) 2}] and [W(CO)4{o-C6H4(CH2TeMe) 2}]

Article abstract of DOI:10.1016/S0022-328X(00)00659-8

The synthesis of the new xylyl-backboned ditelluroether, 1,2-bis(methyltelluromethyl)benzene, o-C₆H₄(CH₂TeMe)₂ (xyte) is described. A range of complexes - [Mn(CO)₃Cl(xyte)], [M(CO)₄(xyte)] (M=Mo or W), [M′Cl₂(xyte)], [M′(xyte)₂][PF₆]₂ (M′=Pd or Pt), trans-[RuCl₂(xyte)₂], trans-[OsCl₂(xyte)₂], [Cu(xyte)₂]PF₆ and [Ag(xyte)₂]CF₃SO₃, have been prepared and characterised by analysis, IR, UV-visible, and multinuclear NMR spectroscopy. The crystal structure of [Mn(CO)₃Cl(xyte)] shows the expected fac geometry with a meso-2 xyte ligand conformation, and the meso-conformation is also found in [W(CO)₄(xyte)]. The xyte complexes provide the first detailed studies of a 7-membered ring ditelluroether chelate, and the properties are compared with those of MeTe(CH₂)₃TeMe or o-C₆H₄(TeMe)₂ to explore the effects of chelate ring size.

Full text of DOI:10.1016/S0022-328X(00)00659-8

www.elsevier.nl/locate/jorganchem
Journal of Organometallic Chemistry 619 (2001) 218–225
Synthesis, spectroscopic and structural characterisation of
complexes of the new ditelluroether
1,2-bis(methyltelluromethyl)benzene, o-C6H4(CH2TeMe)2. X-ray
structures of [Mn(CO)3Cl{o-C6H4(CH2TeMe)2}] and
[W(CO)4{o-C6H4(CH2TeMe)2}]
William Levason *, Bhavesh Patel, Gillian Reid, Antony J. Ward
Department of Chemistry, Uni6ersity of Southampton, Highfield, Southampton SO17 1BJ, UK
Received 3 August 2000; accepted 30 August 2000
Abstract
The synthesis of the new xylyl-backboned ditelluroether, 1,2-bis(methyltelluromethyl)benzene, o-C6H4(CH2TeMe)2 (xyte) is
described. A range of complexes — [Mn(CO)3Cl(xyte)], [M(CO)4(xyte)] (M=Mo or W), [M%Cl2(xyte)], [M%(xyte)2][PF6]2 (M%=
Pd or Pt), trans-[RuCl2(xyte)2], trans-[OsCl2(xyte)2], [Cu(xyte)2]PF6 and [Ag(xyte)2]CF3SO3, have been prepared and characterised
by analysis, IR, UV–visible, and multinuclear NMR spectroscopy. The crystal structure of [Mn(CO)3Cl(xyte)] shows the expected
fac geometry with a meso-2 xyte ligand conformation, and the meso-conformation is also found in [W(CO)4(xyte)]. The xyte
complexes provide the first detailed studies of a 7-membered ring ditelluroether chelate, and the properties are compared with
those of MeTe(CH2)3TeMe or o-C6H4(TeMe)2 to explore the effects of chelate ring size. © 2001 Elsevier Science B.V. All rights
reserved.
Keywords: Telluroether; Copper; Manganese; Platinum metal
¸¹¹¹¹¹º
1. Introduction
TeCH2(CH2)n are formed as well as, or instead of,
RTe(CH2)n+1TeR (n+1=4–6) on reaction of
Cl(CH2)n+1Cl with RTeLi [5]. We recently reported [6]
that the sequential reaction of o-C6H4(CH2Cl)2 with
KTeCN, NaBH4 and a further equivalent of o-
C6H4(CH2Cl)2 in an attempt to make 2,11-ditel-
lura[3,3]orthocyclophane (1), unexpectedly produced
We are currently investigating the synthesis and co-
ordination chemistry of acyclic polydentate and macro-
cyclic ligands containing tellurium donors [1–4]. In
marked contrast to the synthesis of thio- or seleno-ether
analogues for which a wide range of interdonor link-
ages are readily introduced, the weak CꢀTe bonds and
the greater reactivity of the tellurium centres, limits the
interdonor linkages and makes the synthesis of
polydentates a difficult challenge. A common problem
encountered is the elimination of CH2ꢁCH2 and the
formation of ꢀTeTeꢀ linkages during attempts to form
ꢀTeCH2CH2Teꢀ units. Furthermore, tellurocycles
the
monodentate
telluroether
1,3-dihydroben-
zo[c]tellurophene (2). In further studies aimed at incor-
porating o-xylyl linkages into tellurium ligands, we
have now prepared 1,2-bis(methyltelluromethyl)benzene
(a,a%-bis(methyltelluro)-o-xylene, xyte). Upon chelation
to a metal centre seven membered rings are produced
and we have studied a selected range of metal com-
plexes. The effects of the ring size on the spectroscopic
properties of the complexes are established by compari-
son with literature data on 5- and 6-membered ring
analogues, specifically complexes of o-C6H4(TeMe)2
and MeTe(CH2)3TeMe [7–13].
* Corresponding author. Tel.: +44-02380-595000; fax: +44-
02380-593781.
E-mail address: wxl@soton.ac.uk (W. Levason).
0022-328X/01/$ - see front matter © 2001 Elsevier Science B.V. All rights reserved.
PII: S0022-328X(00)00659-8

W. Le6ason et al. / Journal of Organometallic Chemistry 619 (2001) 218–225
219
2. Experimental
2.4. [Pd(xyte)Cl2]
Physical measurements were made as described previ-
ously [6].
To a suspension of [Pd(MeCN)2Cl2] (0.1 g, 0.39
mmol) in MeCN (10 ml) was added xyte (0.15 g, 0.39
mmol) in MeCN (5 ml). The mixture was stirred for 2
h at r.t., and then diethyl ether (20 ml) added, and the
orange–brown powder filtered off and dried in vacuo
(0.184 g, 84%). (Found: C, 21.0; H, 2.2.
2.1. 1,2-Bis(methyltelluromethyl)benzene (xyte)
Under dinitrogen, a frozen solution of LiTeMe made
[5] from MeLi (0.05 mol) and Te powder (6.38 g, 0.05
mol) in dry tetrahydrofuran (200 ml) was treated with
a,a%-dibromo-o-xylene (6.58 g, 0.025 mol) and allowed
to warm to room temperature (r.t.). The mixture was
stirred for 2 h, water (100 ml) added, and the organic
phase separated. The aqueous layer was extracted with
diethyl ether (3×50 ml), and the combined organic
phases dried over magnesium sulphate for 16 h. Filtra-
tion and removal of the solvent in vacuo left a red oil
(6.15 g, 63%). The oil was stored under nitrogen in a
freezer. EI+ mass spectrum: m/z 390, 375, 249; calc. for
C10H14Cl2PdTe2 requires C, 21.2; H, 2.5%.). IR (cm−1
)
(CsI disc) 2983w, 2929w, 1685m, 1575w, 1489s, 1450m,
1408s, 1362m, 1217s, 1200s, 1155m, 1107m, 859m, 771s,
595w, 564m, 430m, 303m (PdCl), 292(PdCl), 276m,
235w. UV–vis (103 cm−1) (mmol dm3 mol−1 cm−1
)
(dmf) 25 300 (3115).
2.5. [Pt(xyte)Cl2]
PtCl2 (0.1 g, 0.38 mmol) was refluxed in MeCN (10
ml) for 2 h, the resulting yellow solution cooled and
filtered. Xyte (0.146 g, 0.38 mmol) in MeCN (5 ml) was
added and the mixture stirred for 2 h at r.t. Filtration
gave the product as a brown powder (0.164 g, 67%).
(Found: C, 18.2; H, 2.1; C10H14Cl2PtTe2 requires C,
18.3; H, 2.2%.). IR (cm−1) (CsI disc) 2991w, 2924w,
1626m, 1575w, 1489s, 1449s, 1361m, 1158m, 1143m,
1061m, 950w, 868s, 837m, 788w, 762s, 749m, 614w,
562m, 311s (PtCl), 293(PtCl). UV–vis (103 cm−1) (dmf)
25 640 (sh).
[C10H Te2]+ 394, [C9H Te2]+ 379, [C9H Te]+ 249.
130
130
130
14
11
11
1H-NMR (CDCl3) 7.09(m, 4H), 4.05(s, 4H), 1.78(s,
6H). 13C{1H}-NMR (CDCl3) 138.1, 130.6, 126.6, 3.7,
−15.5.
2.2. [Cu(xyte)2]PF6
The ligand xyte (0.209 g, 0.54 mmol) in MeCN (5 ml)
was added to a stirred solution of [Cu(MeCN)4]PF6 (0.1
g, 0.27 mmol) in MeCN (15 ml), and the mixture
refluxed for 30 min. The cooled solution was filtered,
concentrated in vacuo to 5 ml, and diethyl ether (20 ml)
added. The pale yellow product was filtered off, and
dried in vacuo (0.22 g, 81%). (Found: C, 29.3; H, 3.0.
C20H28CuF6PTe4·4MeCN requires C, 29.2; H, 3.5%.).
1H-NMR (CDCl3) 7.3–7.0(m), 4.1(s), 1.8(s, MeCN),
1.95(s). IR (cm−1) (CsI disc) 2925m, 2878w, 2280m,
1684m, 1571w, 1490m, 1449m, 1420m, 1362w, 1225m,
1151m, 1056s, 955w, 839s, 764s, 728m, 524m, 448m.
ES+ MS (MeCN): m/z 843, 455; calc. for
2.6. [Pd(xyte)2][PF6]2
To a suspension of [PdCl2(MeCN)2] (0.1 g, 0.39
mmol) in MeCN (10 ml) was added TlPF6 (0.27 g, 0.77
mmol) and the mixture stirred for 2 h at r.t. A solution
of xyte (0.3 g, 0.77 mmol) in MeCN (5 ml) was added
and the mixture stirred for a further 2 h. The solution
was filtered and the filtrate reduced in vacuo to 5 ml.
Diethyl ether (20 ml) was added, and the product
isolated as a brown powder. The product was recrys-
tallised from CHCl3–hexane (0.37 g, 82%). (Found: C,
17.4; H, 2.15; C20H28F12P2PdTe4·4CHCl3 requires C,
17.4; H, 2.0%.). 1H-NMR (acetone-d6) 2.58(br) Me,
4.6(br) CH2, 7.2(br) C6H4. IR (cm−1) (CsI disc) 2972w,
2929w, 1626m, 1576w, 1491s, 1452s, 1364m, 1227m,
1157m, 1104m, 831s, 769m, 585s, 429w. UV–vis (103
cm−1) (mmol dm3 mol−1 cm−1) (dmf) 30 120 (15 320),
22 645 (13 070).
[C20H Te643Cu]+ 851, [C10H Te263Cu]+ 457.
130
28
130
14
2.3. [Ag(xyte)2]CF3SO3
The ligand xyte (0.3 g, 0.78 mmol) in MeCN (5 ml)
was added to a stirred solution of AgCF3SO3 (0.1 g,
0.39 mmol) in MeCN (5 ml), and the mixture stirred for
2 h. The solution was filtered, concentrated in vacuo to
5 ml, and diethyl ether (20 ml) added. The off-white
product was filtered off, recrystallised from CHCl3 and
dried in vacuo (0.21 g, 53%). (Found: C, 21.8; H, 2.3.
C21H28AgF3O3STe4·2CHCl3 requires C, 21.7; H, 2.4%.).
1H-NMR (CDCl3) 7.15(m), 7.03(br), 4.2(s), 2.0(s). IR
(cm−1) (CsI disc) 2925m, 1688w, 1637w, 1574w, 1490s,
1450m, 1419m, 1360m, 1258s, 1230s, 1216s, 1157s,
1028s, 853m, 764s, 636s, 524m, 448m. ES+ MS
2.7. [Pt(xyte)2][PF6]2
Made similarly from [PtCl2(MeCN)2] as a red–brown
powder (64%). (Found: C, 18.5; H, 2.0;
C20H28F12P2PtTe4 requires C, 19.0; H, 2.2%.). 1H-NMR
(acetone-d6) 2.55(br) Me, 4.6(br) CH2, 7.3(br) C6H4.
195Pt-NMR (CDCl3–CH2Cl2 300 K) −4810, −4821.
IR (cm−1) (CsI disc) 2976w, 2934w, 1677m, 1575w,
(MeCN): m/z 887, 496; calc. for [C20H Te1409Ag]+ 897,
130
28
[C10H Te1209Ag]+ 503.
130
14

220
W. Le6ason et al. / Journal of Organometallic Chemistry 619 (2001) 218–225
1492s, 1453s, 1414s, 1361m, 1229m, 1159m, 1102m,
957m, 849s, 767m, 740m, 558s, 426w. UV–vis (103
cm−1) (mmol dm3mol−1 cm−1) (dmf) 26 850 (sh, 8067).
431m, 302m. UV–vis (103 cm−1) (mmol dm3 mol−1
cm−1) (dmf) 24 440 (960).
2.11. [Mo(CO)4(xyte)]
2.8. [Mn(CO)3Cl(xyte)]
A suspension of [Mo(CO)4(piperidine)2] (0.2 g, 0.53
mmol) in CH2Cl2 (10 ml) was treated with the ligand
(0.21 g, 0.53 mmol) in CH2Cl2 (2 ml) and the mixture
refluxed for 1 h. The solution was cooled to r.t. and
hexane was added. The yellow powder was separated
by filtration and dried in vacuo (0.227 g 72%). (Found:
C, 26.3; H, 2.2. C14H14MoO4Te2·CH2Cl2 requires C,
26.4; H, 2.4%). FAB mass spectrum: m/z=598; calc.
To a solution of [Mn(CO)5Cl] (0.1 g, 0.43 mmol) in
CH2Cl2 (5 ml) was added a solution of xyte (0.17 g,
0.43 mmol) in CH2Cl2 (5 ml), and the mixture stirred
for 24 h at r.t. Filtration afforded an orange powder
(0.168 g, 69%). (Found: C, 27.5; H, 2.5.
C15H14ClMnO3Te2 requires C, 27.7; H, 2.5%). ES+
mass
spectrum:
m/z
569,
559;
calc.
for
[C13H ClMnO1330Te2]+ 568, [C12H ClMnO3130Te2]+
for [C14H MoO1430Te2]+ 604. 1H-NMR (CDCl3)
35
14
35
11
98
14
553. 1H-NMR (CDCl3) 1.7(s), 2.28(s), 2.3(s), 2.48(s),
3.43(d), 3.69(d), 3.96(d), 4.11(d), 4.80(d), 5.15(d),
5.49(d), 7.0–7.3(m). 13C{1H}-NMR (CDCl3) 220–215
(br, CO), 135.9, 131.6, 129.0, 13.4, 12.8, 12.5, 11.5,
−7.1, −7.3, −7.6, −8.1. IR (cm−1) (CsI disc)
3022w, 2922w, 2016s, 1932s, 1903s, 1576m, 1487s,
1446s, 1421s, 1359m, 1228m, 1146m, 1109m, 1059m,
856m, 762s, 669s, 630s, 613s, 532m, 512m, 280s. CHCl3
solution 2022(s), 1949(m), 1916(m).
2.27(s), 2.25(sh), 3.7–3.8(m), 5.4(s CH2Cl2), 7.0–
2.25(m). 13C{1H}-NMR (CDCl3) 214.7, 214.9, 211.8,
210.0, 209.8, 136.4, 131.0, 128.1, 23.0, 22.8, −8.1,
−8.5. IR (cm−1) (CsI disc) 2930w, 2850w, 2013vs,
1904vs, 1844vs, 1627m, 1488m, 1455m, 1409m, 1363w,
1219s, 1200w, 1146w, 1135m, 1057m, 950s, 837s, 759s,
622s, 584s, 530m, 478m, 394s, 379s. CHCl3 solution
2022m, 1925vs, 1907vs, 1871s.
2.12. [W(CO)4(xyte)]
2.9. [Ru(xyte)2Cl2]
To a suspension of [W(CO)4(piperidine)2] (0.1 g,
0.215 mmol) in THF (5 ml) was added a solution of the
ligand (0.84 g, 0.215 mmol) in THF (5 ml) and the
reaction mixture refluxed for 24 h, and then stirred at
r.t. for 24 h. The solution was concentrated to 5 ml in
vacuo, hexane added (10 ml), and the product filtered
off. It was washed with hexane and dried in vacuo (0.04
A solution of [Ru(dmf)6][CF3SO3]3 (0.15 g, 0.15
mmol), xyte (0.118 g, 0.3 mmol), and LiCl (0.039 g,
0.91 mmol) were refluxed together in ethanol (15 ml)
for 4 h. The solvent was removed in vacuo and the
residue extracted with CH2Cl2, filtered, and the solvent
reduced to 5 ml. Diethyl ether (20 ml) was added, and
the product isolated as a brown powder, which was
recrystallised from CHCl3–hexane (0.085 g, 57%).
(Found: C, 21.2, H, 2.6; C20H28Cl2RuTe4.3CHCl3 re-
quires C, 21.1; H, 2.4%). ES+ MS m/z 956; calc. for
g,
C14H14O4Te2W.0.5THF requires C, 26.6; H, 2.5%).
FAB mass spectrum: m/z=688; calc. for
27%)
(Found:
C,
26.1;
H,
2.5;.
[C14H14O4130Te1284W]+ 690. 1H-NMR (CDCl3) 2.39(s),
2.36(s), 3.8–3.95(m), 7.0–7.3(m). 13C{1H}-NMR
(CDCl3) 204.8, 204.2, 202.7, 202.4, 201.8, 136.5, 136.0,
131.0, 128.1, 23.7, 23.0, −6.0, −6.5. IR (cm−1) (CsI
disc) 2922m, 2854w, 2006vs, 1870vs, 1839vs, 1490m,
1451m, 1438m, 1407m, 1363m, 1221m, 1137m, 1104m,
1053m, 857m, 838m, 764s, 605s, 577s, 387s. CHCl3
solution 2016s, 1914vs, 1898vs, 1866s.
[C20H Cl1201Ru130Te4]+ 959. IR (cm−1) (CsI disc)
35
28
3013w, 2921w, 1668m, 1629m, 1574m, 1488s, 1449s,
1407s, 1363m, 1098m, 1047m, 838s, 760s, 561m, 517m,
271m. UV–vis (103 cm−1) (dmf)(mmol dm3 mol−1 cm−1
)
27 840 (7374), 22 523 (2530).
2.10. [Os(xyte)2Cl2]
A mixture of [Os(dmso)4Cl2] (0.1 g, 0.17 mmol) and
xyte (0.136 g, 0.35 mmol) in MeCN (15 ml) was
refluxed for 3 h. The solution was cooled and filtered,
and the solvent removed in vacuo. The residue was
extracted with CH2Cl2, concentrated to 5 ml, and di-
ethyl ether (20 ml) added to afford an orange powder
(0.066 g, 36%). (Found: C, 22.9; H, 2.5;
C10H14Cl2OsTe4 requires C, 22.7; H, 2.5%.). ES+ MS
2.13. X-ray structures of [Mn(CO)3Cl(xyte)] and
[W(CO)4(xyte)]
Details of the crystallographic data collection and
refinement parameters are given in Table 1. Crystals of
the former were obtained by diffusion of hexane into an
acetone solution of the complex, and crystals of the
tungsten complex by cooling a CHCl3 solution in a
freezer. Data collection used a Rigaku AFC7S four-cir-
cle diffractometer (T=150 K) with graphite monochro-
m/z 1049, 1003, 969; calc. for [C20H Cl1292Os130Te4]+
35
28
1050, [C19H Cl192Os130Te4]+ 1000, [C19H Os130Te4]+
35
25
192
25
965. IR (cm−1) (CsI disc) 3013w, 2921w, 1489s, 1450s,
1414s, 1363m, 1078s, 1015m, 844m, 765s, 683m, 562m,
mated Mo–Ka radiation (u=0.71073 A). Structure
,
solution and refinement were routine [14–16]. Selected

W. Le6ason et al. / Journal of Organometallic Chemistry 619 (2001) 218–225
221
Table 3
bond lengths and angles are presented in Tables 3 and
,
Selected bond lengths (A) and angles (°) for fac-[Mn(CO)3Cl(xyte)]
4.
Bond lengths
Mn(1)ꢀTe(1)
Mn(1)ꢀTe(2)
Mn(1)ꢀCl(1)
Mn(1)ꢀC(12)
Mn(1)ꢀC(11)
Mn(1)ꢀC(13)
2.6333(9)
2.6199(9)
2.394(2)
1.819(6)
1.808(6)
1.781(6)
3. Results and discussion
The new ditelluroether 1,2-bis(methyltelluromethyl)-
benzene (xyte) was obtained in good yield as a slightly
air sensitive red oil, from LiTeMe and a,a%-dibromo-o-
xylene in THF. It was characterised fully by 1H-,
13C{1H}- and 125Te{1H}-NMR and EI+ mass spec-
trometry.
Bond angles
Te(1)ꢀMn(1)ꢀTe(2)
Te(1)ꢀMn(1)ꢀCl(1)
Te(2)ꢀMn(1)ꢀCl(1)
Te(1)ꢀMn(1)ꢀC(11)
Te(2)ꢀMn(1)ꢀC(12)
Mn(1)ꢀTe(1)ꢀC(1)
Mn(1)ꢀTe(2)ꢀC(10)
C(11)ꢀMn(1)ꢀC(12)
C(11)ꢀMn(1)ꢀC(13)
96.29(3)
86.20(4)
86.82(5)
86.7(2)
86.1(2)
100.3(2)
99.9(2)
90.6(2)
92.4(2)
3.1. Carbonyl complexes
The reaction of [Mn(CO)5Cl] with xyte in CH2Cl2
Table 1
Crystallographic parameters
Table 4
[Mn(CO)3Cl(xyte)] [W(CO)4(xyte)]
,
Selected bond lengths (A) and angles (°) for [W(CO)4(xyte)]
Formula
C13H14ClMnO3Te2 C14H14O4Te2W
Bond lengths
Formula weight
Crystal system
Space group
563.84
685.31
W(1)ꢀTe(1)
W(1)ꢀTe(2)
W(1)ꢀC(1)
W(1)ꢀC(2)
W(1)ꢀC(3)
W(1)ꢀC(4)
2.7907(8)
Monoclinic
C2/c
Orthorhombic
Pbcn
2.792(8)
2.07(1)
1.96(1)
2.04(1)
1.96(1)
Unit cell dimensions
,
a (A)
14.105(3)
10.907(4)
21.058(3)
94.75(2)
3228(1)
8
28.368(3)
7.999(9)
15.149(8)
90
3437(3)
8
,
b (A)
,
c (A)
Bond angles
i (°)
3
Te(1)ꢀW(1)ꢀTe(2)
Te(1)ꢀW(1)ꢀC(1)
Te(1)ꢀW(1)ꢀC(2)
Te(2)ꢀW(1)ꢀC(1)
Te(2)ꢀW(1)ꢀC(3)
Te(2)ꢀW(1)ꢀC(4)
Te(1)ꢀW(1)ꢀC(3)
95.69(3)
91.2(3)
87.4(3)
92.4(3)
91.0(3)
86.9(3)
88.3(3)
,
V (A )
Z
v(Mo–Ka) (cm−1
)
45.28
100.67
3473
Unique observed reflections 3004
Observed reflections with
2416
2199
[Io\2|(Io)]
a
R
0.025
0.027
0.031
0.035
b
Rw
a R=S(ꢀFobsꢀi−ꢀFcalcꢀi)/SꢀFobsꢀi.
b Rw=ꢁ[ꢀwi(ꢀFobsꢀi−ꢀFcalcꢀi)2/SwiꢀFobsꢀi ].
2
produced yellow fac-[Mn(CO)3Cl(xyte)], identified by
an X-ray crystal structure described below. The spec-
troscopic properties are generally similar to those of
other [Mn(CO)3Cl(ditelluroether)] complexes described
elsewhere [10]. In particular the complex exhibits three
w(CO) bands consistent with the Cs structure. The
55Mn-NMR shows three resonances (Table 2) indicative
of slow pyramidal inversion and the presence of three
invertomers (meso-1, meso-2, and DL, Scheme 1), and
there are four corresponding l(125Te) resonances (by
symmetry the meso forms have one resonance each and
Table 2
125Te{1H}- and metal-NMR data a
l(125Te)
l(metal)
Xyte
[Cu(xyte)2]PF6
264
214
+16 (W1/2=12 000 Hz)
63Cu
[Ag(xyte)2]
260
CF3SO3
[Pd(xyte)Cl2]
[Pt(xyte)Cl2]
[Pt(xyte)2][PF6]2
[Mn(CO)3
486
406, 422
−4330, −4342 195Pt
−4821, −4810 195Pt
−553, −660, −770
55Mn
1
the DL two). The H- and 13C{1H}-NMR data (Section
2) are also consistent with the presence of three inver-
tomers, and as in other complexes of this type [10], the
13C-NMR carbonyl resonances are very broad, due to
the substantial 55Mn quadrupole.
251, 252.5, 253.5,
255
Cl(xyte)]
[Mo(CO)4(xyte)] 291, 282
[W(CO)4(xyte)] 199
−1600, −1593 95Mo
The crystal structure [Mn(CO)3Cl(xyte)] (Table 3,
Fig. 1) may be compared with that of [Mn(CO)3Cl{o-
a 125Te shifts relative to neat external Me2Te.

222
W. Le6ason et al. / Journal of Organometallic Chemistry 619 (2001) 218–225
greater in the seven-membered ring (96.29(3)°) com-
pared with the six-membered one (87.60(4)°).
The [W(CO)4(xyte)] and [Mo(CO)4(xyte)] were made
by reaction of xyte with the appropriate
[M(CO)4(piperidine)2]. The cis tetracarbonyl geometry
follows from the presence of four IR active CO
stretches (theory 2A1+B1+B2). In both complexes
pyramidal inversion is slow, revealed by NMR reso-
nances assignable to meso and DL forms, viz. two
l(Me) resonances of unequal intensities in both 1H-
and 13C-NMR spectra, whilst the 13C-NMR in the CO
region show five carbonyl resonances, three for the
meso and two for the DL as expected by symmetry [11].
Curiously, whilst the 125Te-NMR spectrum of the
molybdenum complex shows the expected two reso-
nances, the tungsten complex exhibited only a single
resonance. Since the other NMR spectra show two
invertomers present in a ratio of approximately 1:3, and
there are no cases where inversion at a group 16 donor
is a lower energy process in the W compared with the
Mo carbonyl complex [11], this must be due to acciden-
tal coincidence of the two resonances expected. A yel-
low crystal of [W(CO)4(xyte)] was grown from CHCl3
by cooling in a freezer. The structure (Fig. 2, Table 4)
showed the expected cis geometry with the xyte again
present as the meso invertomer. The geometry is unex-
ceptional with a wide TeꢀWꢀTe angle (95.69(3)°) again
Scheme 1. Invertomers of [Mn(CO)3Cl(xyte)].
C6H4(TeMe)2}] [10]. In both structures the meso-2 in-
vertomer is present (Me groups syn to CO). Compari-
son of the bond lengths about Mn reveal significantly
longer MnꢀTe bonds in the former (2.620(1), 2.633(1))
,
against 2.598(1), 2.613(1) A), whereas the MnꢀCl bond
,
lengths reveal the opposite trend (2.394(2) A in
,
[Mn(CO)3Cl(xyte)] and 2.411(2) A in [Mn(CO)3Cl{o-
C6H4(TeMe)2}]). The MnꢀC bonds are not significantly
different. As might be expected the TeꢀMnꢀTe angle is
Fig. 1. Structure of [Mn(CO)3Cl(xyte)] showing the atom numbering scheme. Atoms are drawn with 40% ellipsoids.

W. Le6ason et al. / Journal of Organometallic Chemistry 619 (2001) 218–225
223
Fig. 2. Structure of [W(CO)4(xyte)] showing the atom numbering scheme. Atoms are drawn with 40% ellipsoids.
attributable to the 7-membered ring. As noted in other
systems including [W(CO)4{[8]aneSe2ꢁ1}] and
[W(CO)4(PR3)2] the WꢀCtransCO are significantly longer
(]8|) than those trans to the ligand [17,18].
of the quadrupolar 63Cu (I=3/2) nucleus deviates to a
greater extent from the cubic symmetry, or that there is
increased tendency to dissociation. Either effect would
promote faster quadrupolar relaxation and lead to
increased line-widths. Nonetheless, the presence of
a
63Cu-NMR resonance is good evidence that
3.2. Homoleptic and metal chloro-complexes
[Cu(xyte)2]+ is a major component of the solution. The
[Ag(xyte)2]CF3SO3 is light sensitive and decomposes in
solution in chlorocarbons to black materials in a few
hours. Similar instability has been noted for other
silver-ditelluroethers [9], and in this case the poor solu-
tion stability prevented a 109Ag-NMR spectrum being
obtained. The 125Te-NMR spectrum contained a weak
singlet at l 260, as with the copper complex a negative,
although in this case smaller, co-ordination shift.
Xyte reacted with [Cu(MeCN)4][PF6] and Ag[CF3-
SO3] in MeCN to give yellow [Cu(xyte)2][PF6] and
off-white [Ag(xyte)2][CF3SO3] respectively. The IR
spectra show characteristic features confirming the an-
ions present, and the ES+ mass spectra show major ion
peaks corresponding to [M(xyte)2]+ and [M(xyte)]+.
1
The H-NMR spectrum of [Cu(xyte)2][PF6] in CDCl3
showed broad singlets for CH2, MeTe and a broad
multiplet for C6H4, little shifted from the resonances of
the free ligand, as expected for complexes of this labile
metal centre [6,8]. The 125Te-NMR spectrum consists of
a single resonance at l 214, a low frequency co-ordina-
tion shift of 50 ppm. Similar low frequency co-ordina-
tion shifts have been observed from other
Cu(I)-telluroethers [8]. The 63Cu-NMR spectrum in
The reaction of xyte with [MCl2(MeCN)2] (M=Pd
or Pt) in MeCN afforded the corresponding
[MCl2(xyte)], whilst use of two equivalents of ligand
and TlPF6 generated the [M(xyte)2][PF6]2 complexes.
The [PtCl2(xyte)] complex showed two l (125Te) and
two l (195Pt)NMR resonances typical of slow pyrami-
dal inversion in trans-ClꢀPtꢀTe systems [7]. For the
[PdCl2(xyte)] complex, only one 125Te-NMR resonance
was observed, which might indicate fast inversion, but
since the signal/noise was poor in the spectrum due to
poor solubility, it is more likely that the second inver-
tomer is of low abundance and escaped detection. The
[M(xyte)2][PF6]2 complexes have better solubility, but as
CH2Cl2 solution at 300 K is a very broad (W1/2
=
12 000 Hz) (Table 1) resonance at +16 ppm (relative
to [Cu(MeCN)4]+) which may be compared with the
range l 21 to −153 observed for CuTe4 chromophores
[8]. The line-width is greater than in most other re-
ported cases, and indicates either that the environment

224
W. Le6ason et al. / Journal of Organometallic Chemistry 619 (2001) 218–225
we have discussed in detail for analogues with o-
C6H4(TeMe)2 or MeTe(CH2)3TeMe [12], the possible
presence of up to five invertomers and the lower pyra-
midal inversion barriers in trans TeꢀMꢀTe systems,
makes observation and assignement of the spectra more
difficult. In the present case of xyte complexes the
1H-NMR spectra contained broad singlets for the CH3
and CH2 groups of the xyte, indicating dynamic pro-
cesses are present at r.t. No 125Te-NMR spectra were
observed at ambient temperatures and the poor solubil-
ity of the complexes prevented low temperature studies.
[RuCl2(xyte)2] was prepared from [Ru(dmf)6]3+, xyte
and LiCl, and [OsCl2(xyte)2] from xyte and
[OsCl2(dmso)4]. The complexes were characterised by
analysis and ES+ mass spectrometry, and identified as
trans geometric isomers by their characteristic UV–vis
spectra [12,13]. Neither complex was sufficiently soluble
in common solvents for NMR studies.
with a range of metal acceptors, although in a number
of cases the solubilities are disappointing, and hindered
spectroscopic studies. In this section we compare some
of the spectroscopic data in an attempt to establish the
effects of the 7-membered ring. The most useful data
for our purposes are the 125Te-NMR shifts, the w(CO)
frequencies in the carbonyl complexes, and the X-ray
data on the Mn complex. The effect of chelate ring size
on 31P-NMR shifts in diphosphine complexes was sys-
tematised by Garrou [19]. He compared the co-ordina-
tion shift D(lcomplex−lligand) of the chelate complex
with that of the ‘equivalent monodentate complex’, the
latter being that containing similar R groups at phos-
phorus. This led to the concept of a ‘chelate ring
parameter’ DR, with 5-membered rings having large
positive DR values, whilst 4- or 6-membered rings had
small or negative DR’s. We showed that similar effects
are present in 77Se- and 125Te-NMR shifts in 5- and
6-membered ring diselenoether or ditelluroether com-
plexes [8,20]. Table 5 summarises the co-ordination
shifts in the 125Te-NMR spectra of comparable com-
plexes of xyte, MeTe(CH2)3TeMe, and o-C6H4(TeMe)2.
Since data are unavailable for many of the ‘equivalent
monodentate complexes’, we were unable to calculate
numerical values for the chelate ring parameters, and
limit the comparison to the co-ordination shifts. As can
be seen these show consistent trends, with large high
frequency shifts in 5-membered rings and small high or
low frequency shifts in 6-membered ring complexes as
expected [8]. The new data on the 7-membered rings in
xyte show the co-ordination shifts are smaller or more
negative than in the 6-ring analogues. Care should be
taken not to over-interpret this, in the absence of data
on the equivalent monodentate ligand. Since it is
known [21] that substituents as remote as the g-carbon
affect the l(125Te) in RTeR%, the equivalent monoden-
tate for xyte would be 2-MeC6H4CH2TeMe which has
not been reported.
4. Some comparisons of 7-, 6-, and 5-membered ring
ditelluroether chelate complexes
The results described in Section 3 show that xyte
forms analogous complexes to other ditelluroethers
Table 5
Some comparisons of 125Te-NMR co-ordination shifts a
b
Complex
D
(xyte)
D(MeTe(CH2)−3
TeMe)
D(o-C6H4-
(TeMe)2)
Ring size
7
6
−10
61
121
150
222
5
289
382
454
242
279
[W(CO)4(LꢀL)]
[Mo(CO)4(LꢀL)]
[Mn(CO)3Cl(LꢀL)]
[PtCl2(LꢀL)]
−65
22
−11
[PdCl2(LꢀL)]
a Data for the 6- and 5-membered ring complexes are taken from
Refs. [7,10,11].
The w(CO) frequencies for comparable carbonyl com-
plexes of the three ditelluroethers (Table 6), show only
small differences, with the A1 mode of the COtransTe
groups in [M(CO)4(LꢀL)] falling xyte ca. o-
C6H4(TeMe)2\MeTe(CH2)3TeMe. A similar ordering
is observed in the manganese complexes, but in both
cases the presence of arylalkyl substituents in o-
C6H4(TeMe)2 and dialkyl in the other two cases should
be considered. The (unknown) MeTe(CH2)2TeMe com-
plexes would have presented a clearer comparison.
b Coordination shift lcomplex−lligand, the lcomplex values are ob-
tained by averaging shifts for the different invertomers.
Table 6
w(CO) Frequencies a
Xyte
MeTe(CH2)−3 o-C6H4(TeMe)2
TeMe
The
X-ray
crystallographic
data
on
[Mo(CO)4-
(LꢀL)]
2022,1925,1907, 2015,1908,1862 2020,1920,1911,
1871 1880
[Mn(CO)3Cl(LꢀL)] (LꢀL=xyte or o-C6H4(TeMe)2)
show rather longer MnꢀTe bonds in the former
(above). Overall the data suggest that the new 7-mem-
bered chelate ring forming ditelluroether is a rather
weaker donor ligand than the 5- or 6-membered ring
analogues, but it still forms quite stable complexes with
a variety of metal centres.
[W(CO)4(LꢀL)] 2016,1914,1898, 2010,1894,1859 2015,1900,1875
1866
[Mn(CO)3-
Cl(LꢀL)]
2022,1952,1918 2021,1949,1906 2026,1957,1916
a Chlorocarbon solution data. Data for 5- and 6-membered rings
taken from Refs. [10,11].

W. Le6ason et al. / Journal of Organometallic Chemistry 619 (2001) 218–225
225
Trans. (1999) 823.
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[6] W. Levason, G. Reid, V.-A. Tolhurst, J. Chem. Soc. Dalton
Trans. (1998) 3411.
The study has also shown that the o-xylyl linkage is
no more prone to CꢀTe cleavage than ꢀ(CH2)3ꢀ or
o-C6H4ꢀ and thus should be a suitable linker in
polydentates or macrocyclic tellurium ligands.
[7] T. Kemmitt, W. Levason, Inorg. Chem. 29 (1990) 731.
[8] J.R. Black, W. Levason, J. Chem. Soc. Dalton Trans. (1994)
3225.
[9] J.R. Black, N.R. Champness, W. Levason, G. Reid, J. Chem.
Soc. Dalton Trans. (1995) 3439.
5. Supplementary material
Crystallographic data for the structural analysis have
been deposited with the Cambridge Crystallographic
Data Centre, CCDC nos. 147360 (Mn) and 147361
(W). Copies of this information may be obtained free of
charge from The Director, CCDC, 12 Union Road,
Cambridge CB2 1EZ, UK (Fax: +44-1223-336033;
e-mail: deposit@ccdc.cam.ac.uk or www: http://
www.ccdc.cam.ac.uk).
[10] W. Levason, S.D. Orchard, G. Reid, Organometallics 18 (1999)
1275.
[11] A.J. Barton, W. Levason, G. Reid, J. Organomet. Chem. 579
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[12] W. Levason, S.D. Orchard, G. Reid, V-A. Tolhurst, J. Chem.
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[14] PATTY, The DIRDIF Program System, P.T. Beurskens, G. Admi-
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Gould, J.M.M. Smits, C. Smykalla, Technical Report of the
Crystallography Laboratory, University of Nijmegen, The
Netherlands, 1992.
Acknowledgements
[15] SHELXS-86, G.M. Sheldrick, Acta Crystallogr. Sect. A 46 (1990)
467.
We thank EPSRC for support of this work.
[16] TEXSAN, Crystal Structure Analysis Package, Molecular Struc-
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[17] M.K. Davies, M.C. Durrant, W. Levason, G. Reid, R.L.
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