Reaction of bis(phenylethynyl)itterbium with tetraphenylantimony halides

Article abstract of DOI:10.1134/S1070363206050070

Phenylethynyl itterbium derivative (PhC≡C)₂Yb(THF) ₂ reacts with tetraphenylantimony halides in tetrahydrofuran (THF) at room temperature to form triphenylantimony, phenylacetylene, benzene, and phenylethynylitterbium PhC≡CYbX(THF)₄ and itterbium YbX ₂(THF)₄ halides; X = Cl, Br, I. The reduction of the antimony derivative is accompanied with the generation of phenyl and phenylethynyl radicals. Pleiades Publishing, Inc., 2006.

Full text of DOI:10.1134/S1070363206050070

ISSN 1070-3632, Russian Journal of General Chemistry, 2006, Vol. 76, No. 5, pp. 705 707.
Pleiades Publishing, Inc., 2006.
Original Russian Text
No. 5, pp. 741 743.
S.F. Zhiltsov, N.A. Pimenova, A.V. Gushchin, V.A. Morgunova, 2006, published in Zhurnal Obshchei Khimii, 2006, Vol. 76,
Reaction of Bis(phenylethynyl)itterbium
with Tetraphenylantimony Halides
S. F. Zhiltsova, N. A. Pimenovaa, A. V. Gushchin**, and V. A. Morgunovab
aNizhnii Novgorod State Pedagogical University, ul. Ul’yanova, Nizhnii Novgorod, 603950 Russia
e-mail: chemical@nnspu.ru
bLobachevskii Nizhnii Novgorod State University, Nizhnii Novgorod, Russia
Received December 20, 2005
Abstract Phenylethynyl itterbium derivative (PhC C)2Yb(THF)2 reacts with tetraphenylantimony halides
in tetrahydrofuran (THF) at room temperature to form triphenylantimony, phenylacetylene, benzene, and
phenylethynylitterbium PhC CYbX(THF)4 and itterbium YbX2(THF)4 halides; X = Cl, Br, I. The reduction of
the antimony derivative is accompanied with the generation of phenyl and phenylethynyl radicals.
DOI: 10.1134/S1070363206050070
We have reported previously [1] on the reaction of
bis(phenylethynyl)itterbium with trimethylsilicon, tri-
phenylgermanium and triphenyltin halides in THF
at room temperature leading basically to formation of
corresponding non-symmetrical organoelement deriva-
tive R3EC CPh (the products of cross-coupling, E =
Si, Ge, Sn) and phenylethynyl itterbium and itter-
bium(II) chlorides. In this work we aimed at the study
of reactivity of bis(phenylethynyl)itterbium toward
tetraphenylantimony halides Ph4SbX (X = Cl, Br, I).
tion of itterbium do not practically change. It is note-
worthy that in contrast to phenylethynyl itterbium
derivatives the bis(pentamethylcyclopentadienyl)it-
terbium does not react with trimethyl silicon chloride
but is readily oxidized by haloalkanes and iodoben-
zene to trivalent state [3].
In the reactions studied by us the expected product
of cross-coupling tetraphenylantimony phenylace-
tylenide was not detected. This fact points to another
character of the reaction, in contrast to the elements
of IVA group organohalides. The high yield of phenyl-
acetylene and benzene in the reaction of bis(phenyl-
ethynyl)itterbium with tetraphenylantimony halides
(see the table) points to participation in the process
of phenylethynyl and phenyl radicas that react with
THF abstracting hydrogen atoms from the latter. It is
very probable that these reactions follow to the me-
chanism of single-electron transfer (see the scheme).
We established that bis(phenylethynyl)itterbium
readily reacts with tetraphenylantimony halides (in
1:2 ratio) in THF at room temperature. The reaction
started just after mixing of the reagents but for
completion the mixture was kept for 24 h. From the
data listed below is seen that the main products are
triphenylantimony, phenylacetylene, benzene and
halides of phenylethynyl itterbium and itterbium(II).
The compounds YbX2(THF)4 are diamagnetics, the
magnetic moment of PhC CYbX(THF)4 is about
0.3 MB (X = Cl, Br, I). In the case of trivalent itter-
bium derivative the moment is 3.8 to 4.3 MB [2].
Hence in the process of oxidation the state of oxida-
Recombination of the radical pair formed does not
occur because it would not result in the formation of
a stable compound [4, 5]. Moreover, phenylethynyl
radical could react with coordinated THF still being
included to the A complex. Stabilization of the metal-
The products of reaction of bis(phenylethynyl)itterbium with Ph4SbX (1:2) in THF at room temperature for 24 h, mol per
1 mol of (PhC C)2Yb(THF)2
X
Ph3Sb
PhC CH
PhH
PhC CYbX(THF)4
YbX2(THF)4
Cl
Br
I
1.83
1.61
1.85
1.15
1.65
1.17
1.01
1.15
1.28
0.70
0.32
0.71
0.25
0.67
0.29
705

706
ZHILTSOV et al.
.
PhC C
Ph4Sb
.
PhC C Yb(C CPh)(THF)2
THF
+ PhC CYbX(THF)4
(PhC C)2Yb(THF)2 + Ph4SbX
+
Ph4Sb
X
A
X = Cl, Br, I.
centered radical proceeds via splitting phenyl radical
off which affords triphenylantimony. In the following
process of the phenyl and phenylethynyl radicals
transformation the state of the carbon atoms oxidation
with unpaired electron grows from 1 to 0. A similar
process of the of phenyl radical formation takes place
in the reaction of sodium tetraphenylboronate with
mixed organomercury, organotin and organolead
compounds [6]. Earlier was reported [7] on the reduc-
tion of triphenylantimony diacetate to triphenylanti-
mony and biphenyl in the reaction with phenylitter-
bium iodide.
5 ml of THF. The reaction rate was the same as the
rate of mixing of the reagents, and in the course of
the process the color was changing from dark violet to
light brown and itterbium(II) chloride precipitate
dropped. For completion, the reaction mixture was
kept for 24 h at room temperature. From the reaction
mixture 0.10 g of YbCl2(THF)4 was isolated, yield
25%, as gold-brown substance, decomp. >300 C.
Found, %: Yb 32.08; Cl 13.30. C16H32Cl2O4Yb.
Calculated, %: Yb 32.51; Cl 13.34.
From the mother liquor the liquid reaction com-
ponents were re-condensed in a vacuum to a trap
cooled with liquid nitrogen. The GLC of the trapped
material detected phenylacetylene 1.17 mmol and
benzene 1.03 mmol.
As seen from the table, among the used tetraphenyl-
antimony halides the most active is bromide. This is
probably a result of the Sb Br bond feature which is
less strong than Sb Cl but more polar than Sb I [8].
These factors affect the step of the single-electron
transfer. The phenylethynyl itterbium halide formed
exerts in part further dealkynylation affording itter-
bium halide YbX2(THF)4. Thus, itterbium phenyl-
ethynyl derivative under the action of tetraphenyl-
antimony halides exerts stepwise dealkynylation
proceeding via formation of free radicals.
Solid residue was triple washed with hexane (10 ml
portions) and dried in a vacuum to constant weight.
0.42 g of PhC CYbCl(THF)4 was isolated as brown
amorphous substance insoluble in hexane, yield 70%,
mp 175 C. Found, %: Yb 28.58; Cl 5.29. C24H37
ClO4Yb. Calculated, %: Yb 28.95; Cl 5.94. IR spec-
1
trum (Vaseline oil), , cm : 2200 medium (PhC C);
2050 medium (C C); 1880 weak, 1790 weak, 1445
strong, 1380 strong, 1300 strong, 1070 medium,
1025 strong, 995 strong, 730 medium, 670 strong,
490 medium, and the adsorption bands at 1040 me-
dium and 840 medium, of the coordinated THF.
EXPERIMENTAL
All operation with the readily oxidizing and hyd-
rolyzing compounds were performed in sealed under
vacuum ampoules with carefully dried and degassed
solvents. IR spectra were taken on an IKS-25 spec-
trometer, the samples were prepared under argon at-
mosphere as suspensions in Vaseline oil. Magneto-
chemical measurements were performed according to
[9].
From the hexane extracts the solvent was removed.
The residue was Ph3Sb (0.66 g), yield 91.5%, a light
yellow low melting substance well soluble in THF,
benzene and hexane. The product was identified by
reaction with acetic acid in the presence of hydrogen
peroxide (see below).
Reaction of (PhC C)2Yb(THF)2 with Ph4SbBr.
To a solution of 0.54 g of (PhC C)2Yb(THF)2 in
15 ml of THF was added 1.06 g of Ph4SbBr dissolved
in 5 ml of THF. Reaction proceeded like the described
above.
Phenylethynyl itterbium derivatives were prepared
by the reaction of itterbium diiodide with sodium
phenylethynylate in THF [10]. Tetraphenylantimony
chloride and bromide were synthesized by known
procedure [4].
The products obtained: (a) 0.43 g of YbBr2(THF)4.
This compound changed its color from green to
yellowish-green during its drying in a vacuum to
constant weight (published data [11]: light green by
color) decomp. >300 C, yield 67 %. Found, %:
Yb 28.81; Br 27.01. C16H32Br2O4Yb. Calculated, %:
Yb 27.85; Br 25.76.
Melting (decomposition) points of the initial and
obtained compounds were determined in sealed ca-
pillary tubes (values are given without correction).
Reaction of (PhC C)2Yb(THF)2 with Ph4SbCl.
To a solution of 0.53 g (PhC C)2Yb(THF)2 in 15 ml
of THF was added 0.95 g of Ph4SbCl dissolved in
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 76 No. 5 2006

REACTION OF BIS(PHENYLETHYNYL)ITTERBIUM
(b) Phenylacetylene and benzene, 1.71 and
707
ACKNOWLEDGMENTS
1.19 mmol, respectively.
This work was performed under financial support
of Federal Education Agency.
(c) 0.22 g of PhC CYbBr(THF)4, brown amor-
phous substance, insoluble in hexane, mp 185 190 C,
yield 32 %. Found, %: Yb 24.18; Br 11.08. C24H37
BrO4Yb. Calculated, %: Yb 26.94; Br 12.46.
REFERENCES
1. Pimanova, N.A., Zhiltsov, S.F., and Druzhkova, O.N.,
(d) Ph3Sb 0.59 g. Yield 80.5%.
Zh. Obshch. Khim., 2003, vol. 73, no. 8, p. 1258.
2. Bochkarev, M.N., Kalinina, G.S., and Zakharov, L.N.,
Organicheskie proizvodnye redkozemel’nykh elemen-
tov (Organic Derivatives of Rare Earth Elements),
Moscow: Nauka, 1989.
Reaction of (PhC C)2Yb(THF)2 with Ph4SbI.
To a solution of 0.52 g of (PhC C)2Yb(THF)2 in
15 ml of THF was added 1.11 g of Ph4SbI dissolved
in 5 ml of THF. Reaction proceeded similarly to the
described above.
3. Finke, R.G. and Keenan, S.R., Organometallics, 1989,
vol. 8, no. 2, p. 263.
The substances obtained: (a) 0.20 g of YbI2(THF)4
as a yellowish-greenish substance (described [11] as
pale yellowis-green crystals) decomp. >300 C, yield
29 %. Found, %: Yb 25.99; I 35.02. C16H32I2O4Yb.
Calculated, %: Yb 24.19; I 35.52.
4. Kocheshkov, K.A., Skoldinov, A.P., and Zemlyan-
skii, N.N., Metody elementoorganicheskoi khimii.
Sur’ma, vismut (Methods in Organoelement Che-
mistry. Antimony and Bismuth), Moscow: Nauka,
1976.
5. Finet, J.-P., Ligand Coupling Reactions With Hetero-
atomic Compounds, Oxford: Pergamon, 1998.
(b) Phenylacetylene (1.17 mmol) and benzene
(1.28 mmol).
6. Shustov, S.B., Bochkaryev, L.N., and Zhiltsov, S.F.,
Metalloorg. Khim., 1990, vol. 3, p. 624.
(c) PhC CYbI(THF)4 (0.49 g), redish-brown
amorphous substance, insoluble in hexane, mp 250 C,
yield 71%. Found, %: Yb 24.93; I 18.25. C24H37
IO4Yb. Calculated, %: Yb 25.10; I 18.43.
7. Rybakova, L.F., Syutkina, O.P., and Petrov, E.S., Zh.
Obshch. Khim., 2000, vol. 70, no. 2, p. 261.
8. Nekrasov, B.V., Osnovy obshchei khimii (Basics of
General Chemistry), Moscow: Khimiya, 1965, vol. 1,
p. 463.
(d) Ph3Sb (0.65 g), yield 92.5%.
9. Protchenko, A.V. and Bochkaryev, M.N., Pribory i
tekhnika eksperimenta (Experimental Methods and
Instruments), Moscow: Nauka, 1990.
Determination of Ph3Sb. To a solution of 0.51 g
Ph3Sb in 0.17 ml of anhydrous CH3COOH was added
0.05 ml of 30% H2O2. Reaction proceeded with the
rate of mixing of the reagents. Triphenylantimony
diacetate formed quantitatively (0.68 g) as a preci-
pitate. The latter was triple washed with hexane (3 ml
portions) and dried, mp 211 213 C (published [4]
213 215 C).
10. Druzhkova, O.N., Pimanova, N.A., and Bochka-
ryev, L.N., Zh. Obshch. Khim., 1999, vol. 69, no. 11,
p. 1801.
11. Watson, P.L., Tulip, T.H., and Williams, I., Organo-
metallics, 1990, vol. 9, no. 7, p. 1999.
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 76 No. 5 2006