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Dimeric Triaryltelluronium Arenetellurolates New Metastable Tetramers of Diaryltellurium.

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(SHELXS-86) and difference Fourier techniques (XTAL 3.0). 370 refined
parameters (W, K. and 0 atoms anisotropic, no H atoms), absorption correction (DIFABS). isotropic extinction correction, uniform weights, final R values: R , = 0.046 [f > 2 d f ) ] and R, = 0.087 (all reflections). Farther details of
the crystal structure investigation may beobtained from the Fachinfomiationszentrum Karlsruhe, D-76344 Eggenstein Leopoldshdfen (Germany), on quoting the depository number CSD-405326.
[lo] K. H Tytko, 0 . Glemser, Z. Nuturforsch. B 1971, 26, 659-678.
[1 11 J. Fuchs, E. P. Flindt. Z. Nu/rrrforsch. B 1979,34, 1393-1404; K. G. Burtseva.
T. S. Chernaya, M. 1. Sirota. SOY.Phjs. Dokl. (Engl. Trund) 1978. 23,
Oxonium salts R,O+ BF,- are known to alkylate alcoholates
very efficiently. Accordingly triphenyltelluronium salts in T H F
solution transfer quantitatively one of their phenyl groups to
tellurolates under mild conditions [Eq. (a)]. This phenyl transfer
+
PhqTeCl
PhzTe
NaTeR
+
RTePh
+
NaCl
784 7x7.
[12]
[13]
[14]
[15]
[16]
W. N Lipscomb. h r g . Clieni. 1965, 4, 132-134.
I. D. Brown. K. K . Wu, Arlu Crystullogr. Seer. B 1975, 32. 1957-1959.
K H. Tytko. Chein. Scr. 1983. 22. 201 -208.
L. Ma, S. Liu. J. Zubietd. Inorg. Chem. 1989, 28. 175-177.
A. Muller. E Krickemeyer, S . Dillinger. J. Meyer, H. Bogge, A. Stammler,
A n g w . Chmi. 1996. 108. 183-185; A n p i , . Chem. Int. Ed. Engl. 1996, 35.
171 173
Dimeric Triaryltelluronium Arenetellurolates :
New Metastable Tetramers of Diaryltelluriumj’”
Jorg Jeske, Wolf-Walther du Mont,* and
Peter G. Jones
Scheme 1
can be inhibited by adding triphenyltelluronium chloride (I)
dissolved in methanol to an ethanolic solution of the sodium
tellurolates 2a,b at low temperatures. At temperatures below -30°C orange powders of Ph,TeTeR (5: 5a, R = p CH,C,H,N; Sb, R = p-CH,OC,H,N) precipitated immediately from the alcoholic solutions. These reactions can be
controlled to yield single crystals of the metastable 5 suitable for
X-ray structure determinations. The by-product, sodium chloride, remains in solution [Eq. (b)].
PhiTeCI
+
1
NaTeR
MeoHEtoH~400C~
Ph3TeTeR
5 a , ~ =C
Za, 2b
Drdicotrd to Professor M a x Herherhold
on the occasion qjlzis 60th birthday
+
NaCl
H
?
~
(b)
5b,R= C H i O a
Scheme 2
Water and its homologous dihydrogen chalcogenides H,E
(E = S, Se, Te) dissociate to only a very limited extent. Neither
their ionic dimers H,E+ E H - nor organic derivatives
R,E+ ER- have been isolated in a pure state. Water dimers are
typically formed by 0 - H . ‘ 0 hydrogen bonds. However, in
the case of sulfur, selenium, and tellurium, metastable “dimers”
R,EER might exist as ion pairs o r as molecular compounds with
covalent chalcogen -chalcogen bonds. The “dimer” of SF,
(S,F4) is indeed the mixed-valent molecule F,S-SF with a covalent S1”-S1 bond.“] Thus the existence and structures of the
hypothetical nonclassical dimeric or oligomeric relatives of
diorganotellurides R,Te are of considerable interest, especially
since it was recognized that contributions from packing of
cations and anions are most important for the structures
of nonclassical polytellurides implying expanded valence
shells.[’ - 4 1 Possible features of “nonclassical diaryltellurium”
compounds could be ionic telluronium tellurolate interactions
(R,Te+ TeR-) and covalent tellurium(1v)- tellurium(II) bonds
(R,Te-TeR, perhaps similar to Bottcher’s CsTe,).[’] Cooperative charge-transfer-like interactions between tellurium atoms
would also be possible. Such interactions are typical for intermolecular contacts in elemental iodine,[’] diorganic ditellurides.[61 and tetraalkyl distibanes,16
and for homonuclear
cation-anion contacts in iodophosphonium iodides.[” These
homonuclear interactions (n + o* overlap) imply hypervalency
of the acceptor atoms.
[*I Pro(. Dr. W-W. d u Mont, Dip1 -Chem. J. Jeske, Prof. Dr. P. G. Jones
Institut fur Anorganische und Analytische Chemie
der Technischen Universitlt
Postfach 3329. D-38023 Brdunschweig (Germany)
Fax ’ Int. code +(531)391-5387
e-mail: dumontw m a d .anchem.nat.tu-bs.de
[**I Properties of Chdlcogen-Chalcogen Bonds. Part 21. This work is supported
by Deutsche Forschungsgemeinschaft and Fonds der Chemischen Industrie.
Part 20: H . U. Meyer, T. Severengiz, WW
: . du Mont. BulI. Soc. Chim. Fr. 1993,
130. 691 694.
A n p e w (%em. In[. Ed. Engl. 1996, 35. N o . 22
>! :
The orange crystals of 5a and 5b are stable below - 18 “C. At
room temperature they decompose gradually, furnishing oily
mixtures of diaryltellurides (Ph,Te 3, PhTeR 4a: R = p CH3C6H,N; 4b: R = p-CH,OC,H,N), which accelerate this
decomposition. Among the products are minor amounts of
diorganic ditellurides (6a,b) and biphenyl (detected by EI mass
spectra). Telluronium tellurolates 5 are insoluble in ethanol,
THF, toluene, and hexane, but slightly soiuble in cold methanol.
However, in solution decomposition takes place even at low
temperature (- 18 “C). Therefore all attempts failed to dissolve
5 for the purpose of recrystallization o r for recording N M R
spectra. Mass spectra always show peaks and fragments of decomposition products [Eq. (c)].
Ph2Te
3
Ph,TeER
5a, b, E = Te
7,E=Se
-
+
PER
4a,b,E=Te
10,E = Se
112 Ph2 + Ph2Te + 112 R2E2
3
6a,b,E=Te
8,E=Se
Scheme 3.
From the class of chalcogenotelluranes o r telluronium
chalcogenolates (R,TeER’, E = 0, S, Se, Te; R = alkyl or aryl)
only the (monomeric) phenoxide compound 9a (that is, E = 0 )
and two derivatives have been structurally characterized.[”] A
nitro function para to the phenoxide leads to longer T e - 0
bonds (9a: 2.294, 9b: 2.461 A). The 2,4,6-trichlorophenoxide
derivative 9c is a dimer with inversion symmetry. T e - 0 distances within the dirner lie between 2.762 and 2.787 .&l’O1
The
first arylthio derivatives (E = S) have been postulated as inter-
VCH Verlugsgesellsrhuft mhH 0-69451 Weinhrim.1996
o570-o~33196i3522-2653$ 15.00+ .?5!0
2653
COMMUNlCATlONS
ly more stable than tellurolate 5a; after thermal decomposition
more diaryldiselenide and biphenyl is formed than with 5a
[Eq. (c), detected by EI-mass spectra and "Se-NMR, ratio of
diarylselenide to diaryldiselenide approximately 2: 11. Solid 7
reveals the same essentially planar, four-membered ring of
chalcogen atoms as in 5a,b (Fig. 2); the average Te-Se distance
(3.1 51 -3.339 A) is about 0.20 8, shorter than the average Te-Te
distance of compounds 5a,b.
9a, R1 = R2= R3 = H
9b, R 1 = R2 = H, R3 = NO2
9c, R' = R2 = R3 = CI (as Tez02 dimer)
mediates in the thermal decomposition of telluronium carboxylates;[' * I they decompose above 0 "C, especially in
X-ray single-crystal structure analyses of the solids 5a and
5b[I3' show cyclic units of the composition R,Te, containing
tellurium - tellurium interactions. These units can be (formally)
regarded as tetramers of diaryltellurium compounds. The nearly
planar Te, rings contain alternate triphenyltelluronium and
aryltellurolate units (Fig. 1). The tellurium-tellurium contacts
Fig.2. Crystal structure of 7.Selected bond lengths [A] and angles ["I: Tel ... Sel
3.3081(8), Tel . . . Se2 3.2768(9), Te2 -.Set 3.1507(8), Te2..-Se23.3388(8); SelTel-Se2 86.382(14),Sel -Te2-Se287.924(14), Tel -Sel-Te2 94.129(14), Tel -Se2-Te2
91.272(14).
Including the bridging chalcogen anions, the acceptor tellurium atoms of the triphenyltelluronium cations of 5a,b and 7
achieve the coordination number 5 (12-Te-5) .[I4] The coordination geometry is (3 2)-distorted, pseudo-tetragonal-monopyramidal. The coordination geometry of the donating chalcogen atoms is trigonal-pyramidal(S-Te-3,8-Se-3).
Thus the solid
state structures of 5a,b and 7 are in accordance with the valence
shell electron pair repulsion (VSEPR) theory. The Te-C bonds
and angles of the triphenyltelluronium fragments are scarcely
distorted by cation-anion interactions.[' Stable monomeric
2.2'-biphenylylene-2-biphenyltellurium phenoxide (10-Te-4) 9a
has a pseudo-tngonal-bipyramidal-coordinatedtellurium center.
The apical Te-C bond of the chelating biphenyl moiety opposite the phenoxide group is considerably longer than the equatorial Te-C bonds (2.103, 2.122 A).r101Dimeric 9c contains two
Te-C bonds trans to bridging oxygen atoms. Only one of
these-the Te-C bond involving the 2-biphenyl substituent-is significally elongated (2.1 59 A). The gradual elongation of
T e - 0 bonds in the sequence of tellurium phenoxides 9a-c reflects the gradual change from predominantly hypervalent covalent bonds (9a) to a more onium-salt-like structure (9c)
Our finding that the Te-Te and Te-Se contacts in 5a,b and 7
are about 0.65-0.70 A longer than the corresponding covalent
bonds of Te" or Se" indicates that the contribution from covalence of the Te-Te and Te-Se interactions is only slight relative
to that of the T e - 0 bond of 9a.
Calculations (EHT, PM3) based on models of 5a,b and 7 with
appropriate symmetry give no indication of explicit bonding
contributions from orbital overlap within Te, or Te,Se, ring
systems.'l6] The compounds can be best described as pairs of ion
pairs. The existence of the solid compounds 5a,b, which are
metastable with respect to the diaryltellurides 3 and 4, as well as
of color (1 and 2 are colorless) and of a geometry in accordance
with VSEPR indicates the importance of cooperative telluriumtellurium interactions in the solids.
+
Fig. I . Crystal structure of 5a. Selected bond lengths [A] and angles ["I: Tel . . Te3
3.5259(13). Tel . . Te4 3.3796(13). Te2 . . 'Tee33.3233(13). Te2... Te4 3.5958( 13);
Te3-Tel-Te4 87.52(3), Te3-Te2-Te487.24(3), Tel-Te3-Te2 93.51(3), Tel-Te4-Te2
91.32(3).
'
( T e . - - T e :5a 3.3233(13), 3.5958(13), 3.3796(13), 3.5259(13); 5b
3.481(2), 3.441(2), 3.396(2), 3.447(2) A) within the four-membered ring system are substantially longer than covalent Te-Te
single bondsr5' and than the distances between hypervalent and
divalent tellurium atoms within solid CsTe,.r21 However, Te-Te
contacts in 5a,b are significantly shorter than the sum of the
van der Waals radii (4.40 A). On average they are slightly shorter than the shortest intermolecular Te-Te distances between
diorganic ditellurides o r the distances between tellurium chains
in elemental tellurium (3.50 A).r4, Corresponding intermoierulur Se-Se interactions in elemental gray selenium are only
slightly shorter (3.44 A);[51but covalent Se-Se bonds are about
0.40 A shorter than Te-Te bonds. Therefore the question arises
whether a mixed tellurium-selenium compound Ph,TeSeR
would exhibit neariy the same chalcogen - chalcogen distances
as its analogues 5a,b or whether the Se-Te distances would be
significantly shorter.
Triphenyltelluronium 4-methylphenylselenolate (7) was isolated analogously to 5a after treating triphenyltelluronium chloride with sodium 4-methylphenylselenolate. The structure of the
metastable yellow -orange crystals was also determined by Xray diffraction at - 130 "C. The selenolate 7 appears to be slight2654
$2
YCH Y c . r l a ~ . ~ ~ e . ~ e lmbH.
l . s ~ h0-69451
u~~
Weinheim. 1996
0570-0H33/9~/3522-2654
X 15.OOt .25/0
Angen. Chem. Int. Ed. E n d . 1996, 35. No. 22
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Experinwntd Procedure
5a.b; 7. To a solution of 1.0mmol sodium aryltellurolate or -selenolaie (freshly
prepared from diarylditellurium and -diselenium. respectively. and sodium borohydride in 20 mL of ethanol) was added triphenyltelluronium chloride (0.39 g,
1 .O mmol) in methanol (20 mL) at -60 C. Immediately a microcrystalline product
precipitated After filtration at -60 -C and washing with ethanol it was dried in
VHCUO. Crystals suitable for X-ray diffraction were obtained by diffusion of the
dissolved starting materials at - 30 C. 5a (triphenyltelluronium4-methylphenyltellurolate): Yield 0.51 g (89%). Elemental analysis of C25H12Te2:calcd C 51.98, H
3.84: found C 57 75. H 4 00. 5b (triphenyltelluronium4-methoxyphenyltellurolate):
Yield 0.47 g (XO0/o) Elemental analysis of C,,H,,OTe,: cakd C 50.58. H 3.74;
found C 50.48. H 3 75 7 (triphenyltelluronium 4-methylphenyl selenolate): Yield
0.35 g (67%) Elemental analysis of C,,H,,SeTe: calcd C 56.76. H 4.19. found C
56.03, H 3.96.
Received: March 21, 1996
Revised version: June 14, 1996 [Z89551E]
German version: Angew. Chmt. 1996. 108. 2822 -2824
Keywords: cations
pounds
. chalcogen
compounds
- tellurium com-
[ l ] F. Seel. A h . Iirorg. Chmr. Rudirichein. 1974. 16, 297.
[2] P. Bottchei-. U Kretschmann, Z.Anorg. AlIg. Cheni. 1985, 523. 145.
. Ed. Engl. 1988.
[3] P. Bdtcher. Ari,qeii~Chern. 1988. IOU. 781 : Angea-. C h ~ n iIn/.
27.759
[4] M. G. Kanatxdis. Angrit Clieni. 1995. 107. 2281 -2283: Angew. Cheni. Int. Ed.
Eilgi. 1995. 34. 2109 -2111.
[ 5 ] A. F Wells. Srrwrurui Inorgnnic Chenrictry. 5th ed., Clarendon Press. Oxford.
Coelenterands: A New Class of
Metal-Encapsulating Ligands
Chris M. Hartshorn and Peter J. Steel*
Heterocyclic tripodal ligands have long been used in coordination and organometallic chemistry,[’] most notably the anionic tripyrazolylborates (scorpionates) ,I231 and their neutral carbon analogues, the tripyrazolylmethane~.[~]
A separate area of
chemistry that has received much attention is the study of
x-arene complexes of transition metals. Benzene forms stable
organometallic complexes with many metals, for example,
[Ru(q6-C6H6)J2 ,Is1 but half-sandwich complexes of ruthenium
(e.g., [Ru(q6-C6H6)LJ2+; L = monodentate ligand) are less
well studied.15. 6] In this paper we bring together for the first time
these two important areas of chemistry and introduce a new
class of ligands, the ~oelenterands.[’~
The structures of these
molecules is such that a coordinated metal is simultaneously
involved in $-bonding to the benzene ring and tripodal coordination to suitably placed heterocycles.
We are currently engaged in the synthesis and study of an
extensive range of compounds (represented by the generalized
structure 1) that comprise a benzene (or other arene) ring to
+
1984.
161 G. Becker. 0 . Mundt in l ~ ’ i r l i o n ~ ~ e n / i Werhs(,/u.irkungeri
oii~~~/~~
in der Chemie
I ~ W / U / / ~ . Y C ~ OEI ’l m w r c , . (Ed. B. Krebs), VCH, Weinheim, 1992, pp. 199-217.
[7] H. 1. Breunig. S . Qiilcc in Dnkonwntionelle Wechsehr-irkungm in dw Chemie
B. Krebs), VCH. Weinheim. 1992, pp. 218--230.
nrcIu//lsl~/t~V
~ / ( ‘ J i i l W / c(Ed.
~,
[8J A. 1. Ashe. A d r . Orgiinorncr. C l i ~ n i1990.
.
30. 77.
W~~t./i,selr~irk~~ngeii
in der Clirmre mrtulli[9] W.-W, du Mont in C~rrh.ori~~mrior~elle
. d 7 l v Elcvnmic,. (Ed.: B. Krebs), VCH. Weinheim, 1992. pp. 231 -244.
[lo] S. Sato. N. Kondo. N. Furukawa, OrgnntiniernNic~ 1994, 13. 3393-3395; S.
Sato, N. Kondo. N. Furukawa. ihid 1995, 14. 5393-5398.
[ l l ] M. Wieher. E. Schmidt, Z.Anorg. Ailg. Chrm. 1988. 556. 189-193.
[12] M. Wieber. S. Rohse. Z.Anorg. Allg. Cltem. 1991. 592. 202-206.
[13] Structure determinations: 5a: C,,,H,,Te,. M , = 1155.25. triclmic. space group
Pi. (I = 12.390(4). h =13.955(4). c = 14.221(4) A. z = 93.28(2), p = 99.96(2),
;.=11425(?) : 1 ’ = 7 1 X 5 . 5 ( 1 1 ) ~ ’ ; % = 2 , p c r i c d = 1 . 7 5 6 M g m ~ ’ : i =
0.71073 pm. 7 = I73 K . the crystal (0.60 x 0.41 x 0.06 mm) was mounted in
inert oil. The intensities were measured to 20 50 using Mo,, radiation on a
Sirinens R 3 diffractometer. Of 7755 reflections. 7383 were unique (R,,, =
0.01XI) and uscd for all calculations (programm SHELXL-93). After absorption correction (psi-scans). the structure was solved by direct methods and
relined anisotropically on F2.The final wR2 war 0.0959 with conventional
R ( F ) 0 0359. 489 parameters. and 468 restraints, max. Ap 1262
5b:
C,,,H,,O,Te,.
.M, = 1187.25. triclinic, space group Pi: u = 12 344(5).
h = 1 3 . 5 0 3 ( 6 ) . ( =15267(6)A.1=93.51(4)./j= 98.99(4).;=115.30(4) : V =
2248.2(16),&. % = 2 ; pLJ,cd
=1.754Mgm-’. .; =0.71073pm, T = 1 7 3 K ;
0.80 x 0.54 x 0.03 mm, 213 range 6-55 . ahsorption correction (SHELXA).
XX1X data. 8x17 unique, structure solved and refined a s above, ir-RZ = 0.1803.
Rl = 0 0542, 507 parameters. and 474 restraints; max. A p 1496enm-’. 7:
C,,,H,,Sc,Te,.
M ,= 3057.97; triclinic. space group Pi: (I =12.108(3).
h=13.96X(3). ( =14.169(3)8\. ~ = 9 3 . 7 5 1 ( 1 0 ) ,p=100.64(1),;. =114.04(1) :
b‘= 3 1 2 4 2 ( 8 ) A ” . Z = 2;p,,,,, =1.654Mgm-3.j.=0.71073pm, T = 1 4 3 K :
0.50 x 0.50 x 0.35 mm. 20 range 6-50 , absorption correction (psi-scans), 7969
data. 7589 unique. STOE Stadi-4 diffractometer; structure solved by using
non-hydrogen ;itom coordinates of 5a. refinement as above, wR2 = 0.0763.
R1 = 0.0267.4X9 parameters and 468 restraints: max. A p 948 enm-’. Because
of similar cell dimensions and atomic positions these crystal structures can be
treated as isostructural. Crystallographic data (excluding structure factors) for
the structures reported in this paper have been deposited with the Cambridge
Crystnllographic Data Centre as supplementary publication no. CCDC-17911 3 . (‘opies o f the data can be obtained free of charge on application to The
Director. CCDC. 17 Union Road. Cambridge CB2 1EZ. UK (fax: int.
code + (1723).336-033, e-mail: teched!o chemcrys.cam.ac.uk)
[14] (12-Te-5)means that 12 valence electrons surround the central atom Te. which
has 5 substitucnts C W Perkins. J. C. Martin. A. J. Arduengo 111. W. Lau, A.
J . 1980. 102. 7753.
Alegriii. J K. Kochi. J. Ani. C ~ P I ?Sot..
[15] I. Haiduc. R. B. King. M. G. Newton, Chein. Rey. 1994, 94. 301-326.
[16] C. .I;iniak. unpublished results.
Anpew. C h m . Inr. Ed. Engl. 1996. 35. No. 22
7‘:
1
4
3
which are appended multiple heterocyclic rings connected
through a variety of spacer groups. These polyheteroaryl-substituted arenes exhibit a variety of modes of coordination to different transition metals.[*] We recently reported[’’ the syntheses of
a number of poly(pyrazo1-I -ylmethyl)benzenes including the
1,3,5-tri(pyrazol-l -ylmethyl)benzenes (2a,b), and speculated
that such compounds might act as tripodal chelating ligands, as
in 3, or even encapsulate a metal with additional coordination
to the benzene ring, as in 4. We now report the successful realization of this second mode of coordination.
Reaction of 2b, readily available in two steps from
mesitylene,[’] with [Ru(dmso),C1,] in ethanol/water at reflux
[*I
Dr. P. J. Steel, C. M. Hartshorn
Department of Chemistry
University of Canterbury, Christchurch (New Zealand)
Fax. Int. code +(3)3642110
e-mail: p.steel(u chem.canterbury.ac.nz
VCH Verlug.~geseNschuftmbH, 0-69451 Weinheim, 1996
o57o-oR33/96/3522-265S3 1 5 . U O i .25:0
2655
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