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A convenient synthesis of lanthanoid trihalides in tetrahydrofuran
INORG. NUCL. CHEM. LETTERS Vol.15, pp. 263-265 Pergamon Press Ltd. 1979. Printed in Great Britain
A
CONVENIENT
SYNTHESIS
OF
LANTHANOID
TRIHALIDES
IN
TETRAHYDROFURAN
G.B. Deacon and A.J. Koplick Chemistry Department, Monash University,
Clayton, Victoria 3168, Australia
(Received 26 January 1979) The transmetallation reaction 1 has been used for the preparation of many lanthanoid trihalides
(1,2), and reaction 2 has been used to give thulium and samarium diiodides
3HgX 2
+
HgI 2
+
2M
÷
2MX 3
M
÷
MI 2
The experimental procedure is rather complex.
+
+
(3,4).
3Hg
1
Hg
2
Thus, in the most general application
(i), a
sealed tube reaction at 300°C is followed by removal of mercury species by distillation, the trihalide is purified by sublimation under very dry argon. compounds have been prepared
(5) by the transmetallation
and then
Recently some organoytterbium
reaction 3 in tetrahydrofuran
(THF).
THF R2Hg
+
Yb
"~ R2Yb
+
Hg
3
We now report that reaction 1 proceeds readily in tetrahydrofuran giving a simple synthesis of lanthanoid trihalides. The reactions of lanthanoid metals
(generally in excess) with mercuric halides
(Table i)
were carried out in Schlenk assemblies under dry nitrogen giving a precipitate of mercury metal and either a solution or a suspension of the lanthanoid trihalide. (YbCI3,ErCI3), the warm
In the former case
(50°C) reaction mixture was filtered through a celite pad, and the
tetrahydrofuran complex of the lanthanoid trihalide was isolated by evaporation of the filtrate to crystallization.
In the latter case
(YbBr3,YbI3,SmI3),
the reaction mixture was inverted into
the thimble of a Soxhlet assembly, and the lanthanoid trihalide complex was obtained by extraction with tetrahydrofuran under nitrogen.
Preparations
and extractions of the less soluble
halides were carried out under "grease-free" conditions using teflon taps and sleeves. highly moisture-sensitive
The
solid products were manipulated under dry nitrogen in a recirculating
atmosphere dry box. The lanthanoid trihalide complexes
(Table i) were identified by metal and halogen
analyses, the stoicheiometries of the YbCl3,YbBr3, those reported
(6).
and ErCI 3 derivatives being in agreement with
All compounds gave negative mercury analyses.
analyses of representative
Attempts to obtain C,H micro-
compounds in sealed aluminium capsules gave unsatisfactory and
263
264
Synthesis of Lanthanoid Trihalides
TABLE
1
Preparations of Some Lanthanoid Trihalides
a
Mercuric Salt mmol
Metal
mg atom
Yb
4.36
HgCl 2
Yb
6.06
HgCl 2
THF ml
Reaction Temp(°C)
Time(h)
Yield ~ (%)
5.95
30
60-65
0.25
YbCI3(THF) 3
52
2.14
45
60 - 65
0.75
YbCI3(THF) 3
35 87
Product
Yb
2.60
HgCl 2
1.22
40
40 - 6 0
1.0
b YbCI 3
Yb
5.09
HgBr 2
3.05
40
65
2.0
YbBr3(THF)3d
27
Yb
4.05
HgI 2
3.02
30 d
65
2.0
YbI3(THF)3e
37
Sm
3.06
HgI 2
2.88
25 d
65
1.5
8mI3(THF)3°
16
Er
2.57
HgCI 2
2.88
65
5 0 - 60
1.0
ErCI3(THF) 3. 5
62
Based on the mercuric salt,
b
Yield of compound in solution after filtration to remove
mercury metal and the excess of ytterbium.
Found Cl/Yb ratio for the solution species, 2.94.
Following reaction, the trihalide was separated from mercury and the excess of lanthanoid
d Further THF added (to give 50 ml total) before
metal by Soxhlet extraction for l-2h. extraction.
irreproducible
results.
Thermogravimetric
analysis of YbC13(THF) 3 and ErCI3(THF)3. 5 resulted in
partial loss of tetrahydrofuran at ca. 60 - 360°C giving products similar to those obtained heating the complexes under isothermal conditions.
(7) on
However, the new complexes YbI3(THF) 3 and
SmI3(THF) 3 underwent reductive decomposition at 140 - 220°C and 120 - 180°C respectively.
2MI3(THF) 3
÷
2MI2(THF) 1.5
+
I2
+
3THF
Evolution of iodine was independently detected on heating a sample of YbI3(THF) 3 under vacuum at 200°C.
The infrared spectra of the complexes showed intense absorption at i010 - 995 and
860 - 830 cm -I attributable
(8) to ring stretching modes of coordinated tetrahydrofuran.
Thus, transmetallation reactions in tetrahydrofuran provide a convenient route to lanthanoid trihalides under anhydrous conditions.
It may be unnecessary to isolate the
trihalides when they are needed for further reactions,
since tetrahydrofuran is a suitable
medium for treatment with a variety of reagents, especially reactive organometallics. of the precipitate and filtrate from a reaction of ytterbium with mercuric chloride indicated that transmetallation was complete
(100% Hg metal in the precipitate)
filtered solution contained ytterbium trichloride in very high yield.
Analysis (Table i)
and that the
A novel feature of the
present work is the successful preparation of samarium and ytterbium triiodides, which could not
Synthesis of Lanthanoid Trihalides
previously be obtained by transmetallation
(2,cf. 4).
265
The formation of ytterbium trihalides
(reaction I,M = Yb) in tetrahydrofuran contrasts with the formation of di___organoytterbiem compounds in organometallic transmetallations
Acknowledgements:
(reaction 3).
We are grateful to Dr. John Hill, Latrobe University,
for thermogravimetric
analyses and to the Australian Research Grants Com~ittee for support.
References
i.
F.L. CARTER and J.F. MURRAY,
2.
L.B. ASPREY, T.K. KEENAN, and F.H. KRUSE,
3.
L.B. ASPREY and F.H. KRUSE,
4.
C. HIRAYA~IA, P.M. CASTLE, R.W. LIEBERMANN, Inorg. Chem., 13, 2804
5.
6.
Mat. Res. Bull., 7, 519
(1972).
Inorg. Chem., 3, 1137
J. Inorg. Nucl.
(1964).
Chem., 13, 32 (1960).
R.J. ZOLLWEG,
and F.E. CAMP,
(1974).
G.B. DEACON, W.D. RAVERTY, and D.G. VINCE, J. Organomet.
Chem., 135, 103
G.B. EEACON and A.J. KOPLICK, J. Organomet.
Chem., 146, C43
(1978).
K. ROSSMANITH and C. AUER-WELSBACH, Monatsh.
Chem., 96, 602
(1965);
K. ROSSMANITH,
Monatsh.
Chem., 97, 1357
7.
K. ROSSMANITH and C. AUER-WELSBACH,
8.
J. LEWIS, J.R. MILLER,
(1966);
Monatsh.
i00, 1484
Chem.,
96, 606
(1977);
(1969). (1965).
R.L. RICHARDS, and A. THOMPSON, J. Chem. Soc., 5850
(1965).
A
CONVENIENT
SYNTHESIS
OF
LANTHANOID
TRIHALIDES
IN
TETRAHYDROFURAN
G.B. Deacon and A.J. Koplick Chemistry Department, Monash University,
Clayton, Victoria 3168, Australia
(Received 26 January 1979) The transmetallation reaction 1 has been used for the preparation of many lanthanoid trihalides
(1,2), and reaction 2 has been used to give thulium and samarium diiodides
3HgX 2
+
HgI 2
+
2M
÷
2MX 3
M
÷
MI 2
The experimental procedure is rather complex.
+
+
(3,4).
3Hg
1
Hg
2
Thus, in the most general application
(i), a
sealed tube reaction at 300°C is followed by removal of mercury species by distillation, the trihalide is purified by sublimation under very dry argon. compounds have been prepared
(5) by the transmetallation
and then
Recently some organoytterbium
reaction 3 in tetrahydrofuran
(THF).
THF R2Hg
+
Yb
"~ R2Yb
+
Hg
3
We now report that reaction 1 proceeds readily in tetrahydrofuran giving a simple synthesis of lanthanoid trihalides. The reactions of lanthanoid metals
(generally in excess) with mercuric halides
(Table i)
were carried out in Schlenk assemblies under dry nitrogen giving a precipitate of mercury metal and either a solution or a suspension of the lanthanoid trihalide. (YbCI3,ErCI3), the warm
In the former case
(50°C) reaction mixture was filtered through a celite pad, and the
tetrahydrofuran complex of the lanthanoid trihalide was isolated by evaporation of the filtrate to crystallization.
In the latter case
(YbBr3,YbI3,SmI3),
the reaction mixture was inverted into
the thimble of a Soxhlet assembly, and the lanthanoid trihalide complex was obtained by extraction with tetrahydrofuran under nitrogen.
Preparations
and extractions of the less soluble
halides were carried out under "grease-free" conditions using teflon taps and sleeves. highly moisture-sensitive
The
solid products were manipulated under dry nitrogen in a recirculating
atmosphere dry box. The lanthanoid trihalide complexes
(Table i) were identified by metal and halogen
analyses, the stoicheiometries of the YbCl3,YbBr3, those reported
(6).
and ErCI 3 derivatives being in agreement with
All compounds gave negative mercury analyses.
analyses of representative
Attempts to obtain C,H micro-
compounds in sealed aluminium capsules gave unsatisfactory and
263
264
Synthesis of Lanthanoid Trihalides
TABLE
1
Preparations of Some Lanthanoid Trihalides
a
Mercuric Salt mmol
Metal
mg atom
Yb
4.36
HgCl 2
Yb
6.06
HgCl 2
THF ml
Reaction Temp(°C)
Time(h)
Yield ~ (%)
5.95
30
60-65
0.25
YbCI3(THF) 3
52
2.14
45
60 - 65
0.75
YbCI3(THF) 3
35 87
Product
Yb
2.60
HgCl 2
1.22
40
40 - 6 0
1.0
b YbCI 3
Yb
5.09
HgBr 2
3.05
40
65
2.0
YbBr3(THF)3d
27
Yb
4.05
HgI 2
3.02
30 d
65
2.0
YbI3(THF)3e
37
Sm
3.06
HgI 2
2.88
25 d
65
1.5
8mI3(THF)3°
16
Er
2.57
HgCI 2
2.88
65
5 0 - 60
1.0
ErCI3(THF) 3. 5
62
Based on the mercuric salt,
b
Yield of compound in solution after filtration to remove
mercury metal and the excess of ytterbium.
Found Cl/Yb ratio for the solution species, 2.94.
Following reaction, the trihalide was separated from mercury and the excess of lanthanoid
d Further THF added (to give 50 ml total) before
metal by Soxhlet extraction for l-2h. extraction.
irreproducible
results.
Thermogravimetric
analysis of YbC13(THF) 3 and ErCI3(THF)3. 5 resulted in
partial loss of tetrahydrofuran at ca. 60 - 360°C giving products similar to those obtained heating the complexes under isothermal conditions.
(7) on
However, the new complexes YbI3(THF) 3 and
SmI3(THF) 3 underwent reductive decomposition at 140 - 220°C and 120 - 180°C respectively.
2MI3(THF) 3
÷
2MI2(THF) 1.5
+
I2
+
3THF
Evolution of iodine was independently detected on heating a sample of YbI3(THF) 3 under vacuum at 200°C.
The infrared spectra of the complexes showed intense absorption at i010 - 995 and
860 - 830 cm -I attributable
(8) to ring stretching modes of coordinated tetrahydrofuran.
Thus, transmetallation reactions in tetrahydrofuran provide a convenient route to lanthanoid trihalides under anhydrous conditions.
It may be unnecessary to isolate the
trihalides when they are needed for further reactions,
since tetrahydrofuran is a suitable
medium for treatment with a variety of reagents, especially reactive organometallics. of the precipitate and filtrate from a reaction of ytterbium with mercuric chloride indicated that transmetallation was complete
(100% Hg metal in the precipitate)
filtered solution contained ytterbium trichloride in very high yield.
Analysis (Table i)
and that the
A novel feature of the
present work is the successful preparation of samarium and ytterbium triiodides, which could not
Synthesis of Lanthanoid Trihalides
previously be obtained by transmetallation
(2,cf. 4).
265
The formation of ytterbium trihalides
(reaction I,M = Yb) in tetrahydrofuran contrasts with the formation of di___organoytterbiem compounds in organometallic transmetallations
Acknowledgements:
(reaction 3).
We are grateful to Dr. John Hill, Latrobe University,
for thermogravimetric
analyses and to the Australian Research Grants Com~ittee for support.
References
i.
F.L. CARTER and J.F. MURRAY,
2.
L.B. ASPREY, T.K. KEENAN, and F.H. KRUSE,
3.
L.B. ASPREY and F.H. KRUSE,
4.
C. HIRAYA~IA, P.M. CASTLE, R.W. LIEBERMANN, Inorg. Chem., 13, 2804
5.
6.
Mat. Res. Bull., 7, 519
(1972).
Inorg. Chem., 3, 1137
J. Inorg. Nucl.
(1964).
Chem., 13, 32 (1960).
R.J. ZOLLWEG,
and F.E. CAMP,
(1974).
G.B. DEACON, W.D. RAVERTY, and D.G. VINCE, J. Organomet.
Chem., 135, 103
G.B. EEACON and A.J. KOPLICK, J. Organomet.
Chem., 146, C43
(1978).
K. ROSSMANITH and C. AUER-WELSBACH, Monatsh.
Chem., 96, 602
(1965);
K. ROSSMANITH,
Monatsh.
Chem., 97, 1357
7.
K. ROSSMANITH and C. AUER-WELSBACH,
8.
J. LEWIS, J.R. MILLER,
(1966);
Monatsh.
i00, 1484
Chem.,
96, 606
(1977);
(1969). (1965).
R.L. RICHARDS, and A. THOMPSON, J. Chem. Soc., 5850
(1965).