Specific chemical behavior of NdII and DyII iodides in reactions with aromatic compounds

Article abstract of DOI:10.1023/A:1021364804963

Benzene, toluene, tert-butylbenzene, or biphenyl virtually do not react with NdI₂ (1) or DyI₂ (2) in THF at -20°C but appreciably accelerate the reactions of these salts with solvents, resulting in LnI₃ and intractable mixtures of products of the general composition [LnI(H)(R)(THF)] (R are fragments of the THF molecule). The same effect is induced by the addition of diphenylmercury or tetraphenyltin to solutions of 1 or 2. Phenol easily oxidizes 1 and 2 to give at 0°C the PhOLnI ₂(THF)_x complexes (x = 3, 4) in 55-95% yields. At -90°C, iodide 2 is converted into a similar complex PhODyI ₂(THF)₄, whereas 1 gives a mixture of PhONdI ₂(THF)₄, (PhO)₂NdI(THF)₅, NdI ₃(THF)₃, and [NdI(H)R(THF)]. A plausible pathway of the reactions including the intermediate formation of extremely reactive monovalent lanthanide iodides LnI is discussed.

Full text of DOI:10.1023/A:1021364804963

Russian Chemical Bulletin, International Edition, Vol. 51, No. 10, pp. 1909—1914, October, 2002
1909
Specific chemical behavior of NdII and DyII iodides
in reactions with aromatic compounds
ꢀ
M. N. Bochkarev, A. A. Fagin, and G. V. Khoroshenkov
G. A. Razuvaev Institute of Organometallic Chemistry, Russian Academy of Sciences,
49 ul. Tropinina, 603950 Nizhny Novgorod, Russian Federation.
Fax: (831 2) 66 1497. Eꢀmail: mboch@imoc.sinn.ru
Benzene, toluene, tertꢀbutylbenzene, or biphenyl virtually do not react with NdI2 (1) or
DyI2 (2) in THF at –20 °C but appreciably accelerate the reactions of these salts with solꢀ
vents, resulting in LnI3 and intractable mixtures of products of the general composition
[LnI(H)(R)(THF)] (R are fragments of the THF molecule). The same effect is induced by the
addition of diphenylmercury or tetraphenyltin to solutions of 1 or 2. Phenol easily oxidizes 1
and 2 to give at 0 °C the PhOLnI2(THF)x complexes (x = 3, 4) in 55—95% yields. At –90 °C,
iodide 2 is converted into a similar complex PhODyI2(THF)4, whereas 1 gives a mixture of
PhONdI2(THF)4, (PhO)2NdI(THF)5, NdI3(THF)3, and [NdI(H)R(THF)]. A plausible pathꢀ
way of the reactions including the intermediate formation of extremely reactive monovalent
lanthanide iodides LnI is discussed.
Key words: neodymium, dysprosium, iodide, reduction, aromatic hydrocarbon.
The convenient methods for the synthesis of molecuꢀ
lar iodides of divalent thulium,1 dysprosium,2 and neodyꢀ
mium2 developed recently made these salts available
for further structural and chemical studies. XꢀRay difꢀ
catechol, 3,6ꢀdi(tertꢀbutyl)benzoꢀ1,2ꢀquinone,10а cycloꢀ
octatetraene, acenaphthylene,10b and calix[4]arene10c also
demonstrated high reducing capacity of this salt. The
chemical properties of iodides 1 and 2 have scarcely been
studied, although indirect data attest to a very high reacꢀ
tivity of these substances.2 This has been confirmed5 by the
data that DyI2 readily reduces naphthalene to the dianion
in dimethoxyethane (DME) to give the C10H8DyI(DME)2
complex and adds at the triple bond of diphenylacetylene
to give, after hydrolysis, cisꢀstilbene. The addition of
C6H5CH2CH2Cl to cyclohexanone in the presence of
DyI2 occurs at –45 °C, whereas TmI2 reacts only at 60 °C.
This paper deals with the unusual behavior of THF
solutions of NdI2 (1) and DyI2 (2) in the presence of
aromatic hydrocarbons and their derivatives. The results
were interpreted by assuming a set of reactions that inꢀ
clude the formation, under certain conditions, of exꢀ
tremely potent reducing agents, monovalent metal ioꢀ
dides LnI.
1
fraction analysis showed that the TmI2(DME)3
3
and NdI2(THF)5 molecules have
a pentagonalꢀ
bipyramidal geometry, similar to that of samarium
complexes SmI2(THF)5, SmI2(DME)(THF)3, and
SmI2(DME)2(THF).4 In the crystal of the dysprosium
analog DyI2(DME)3, two conformers were found,5 one
with linear and one with bent I—Dy—I fragment. Comꢀ
parison of the electrode potentials of Sm, Tm, Dy, and
Nd (Eo (Ln3+/Ln2+) = –1.55, –2.3, –2.45, and –2.62 V,
respectively6) leads to the suggestion that the reductive
properties of divalent metal iodides markedly increase on
passing from samarium to thulium, dysprosium, and
neodymium. This assumption is confirmed by the subꢀ
stantial decrease in the stability of solutions of LnI2 in
THF (i.e., acceleration of reactions with the solvent) in
the series SmI2 > TmI2 > DyI2 > NdI2.7 Note that lanꢀ
thanide iodides LnIx (Ln = Sc, Y, La, Ce, Pr, x = 1.8—2.3)
containing the metal in the +3 oxidation state exhibit
relatively low reactivities.8 These compounds, possessing
metalꢀtype conduction, are designated by the general forꢀ
mula (Ln3+)(e–)(I–)x. Comparison of the reducing caꢀ
pacities of SmI2 and TmI2 in the crossꢀcoupling of keꢀ
tones and alkyl halides9 showed that in the case of thuꢀ
lium iodide, the reaction time is markedly shorter and the
product yield is higher. Our studies into the reactivity of
TmI2 toward alcohols, namely, 3,6ꢀdi(tertꢀbutyl)pyroꢀ
Results and Discussion
Both iodides 1 and 2 are insoluble in benzene or toluꢀ
ene and do not react with these hydrocarbons. The solꢀ
vated salts NdI2(THF)5 and DyI2(THF)5 are also insoluble
in aromatic solvents but, when placed in benzene at
–10 °C, the crystals of these compounds acquire a darkꢀ
brown color and collapse over a period of 10 to 20 min.
When benzene is added in any ratio (even in trace
amounts) to a solution of 1 or 2 in THF at –30 °C, the
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 1757—1762, October, 2002.
1066ꢀ5285/02/5110ꢀ1909 $27.00 © 2002 Plenum Publishing Corporation

1910
Russ.Chem.Bull., Int.Ed., Vol. 51, No. 10, October, 2002
Bochkarev et al.
initial violet (Nd) or khakiꢀgreen (Dy) color of the soluꢀ
tion changes to darkꢀbrown after several minutes and the
compound LnI3(THF)3 precipitates. The amount of the
triiodide formed corresponds to a half of LnI2 used in the
reaction.
tion [LnI(H)R(THF)x] (Nd, x = 2; Dy, x = 1). Fracꢀ
tional solubility of А in various solvents attests that this
is not a single compound but is, apparently, a mixꢀ
ture of [LnI(H2)(THF)x], [LnI(H)R(THF)x], and
[LnI(R)R´(THF)x] complexes. These compounds may
result from the reaction of LnI2 only with the solvent.
Note that lanthanide derivatives containing Ln—H and
Ln—C bonds are commonly colored brown.12 The small
amount of benzene found in the hydrolysis products obꢀ
tained from А may be due either to its incomplete removal
during vacuum drying or to the presence in А of Ln—C6H5
groups resulting from the reaction of benzene with lanꢀ
thanide iodide. The fact that THF containing traces
of aromatic compounds can be completely purified
when treated with iodides 1 and 2 supports the latter
assumption.
Similar transformations, i.e., the formation of LnI3
and brown [LnI(H)R(solv.)x] products, take place when
the reactions are carried out in DME or when other aroꢀ
matic compounds such as toluene, ButC6H5, diphenyl,
stilbene, Ph2Hg, or Ph4Sn are added to solutions of 1
and 2. Meanwhile, aliphatic hydrocarbons, diethyl ether,
or even (Me3Si)2NH, which contains an active hydrogen
atom, have no influence on the solutions of the iodides
studied.
Apart from LnI3(THF)3, compound А having identiꢀ
cal properties in both cases was isolated from the reaction
mixture as a brown noncrystalline pyrophorous powder
soluble in THF and DME and partially soluble in ether,
benzene, and toluene, but insoluble in hexane. The
metal and iodine contents in substance А correspond to
the formal composition LnI(THF)x (Ln = Nd, x = 3;
Ln = Dy, x =2). The atomic magnetic moment of the
neodymium derivative (3.4 µB) corresponds to NdIII
.
Its IR spectrum contains only bands for coordinated
THF molecules (1010 and 860 cm–1) and lowꢀintenꢀ
sity bands at 1350, 1300, 1240, 1180, 1070, 910, 850,
650, and 540 cm–1, which can be assigned to vibraꢀ
tions of the Ln—H, Ln—O—CH2—, Ln—CH=CH2, or
—CH=CH—CH=CH— groups. The spectrum of the dysꢀ
prosium product АDy differs only by a somewhat lower
intensity of the bands at 1010 and 860 cm–1. According to
GLC and 1H NMR spectroscopy, the volatile products of
reactions of 1 and 2 with stoichiometric amounts of benꢀ
zene contained >80% of the initial C6H6.
Since neither Xꢀray diffraction nor NMR spectroscopy
(the latter, due to the presence of the paramagnetic metal)
is applicable to the study of compound А, indirect chemiꢀ
cal routes were employed to identify this product. Hyꢀ
drolysis of АNd was found to give only NdI(OH)2, THF,
H2, and benzene in 1 : 1.1 : 1.2 : 0.07 ratio. In addition,
chromatographic analysis of the volatile fraction showed
the presence of minor amounts of four other products,
which could not be identified. The separation of inorꢀ
ganic and volatile components left a brown thick metalꢀ
free material; according to IR and 1H NMR spectroꢀ
scopy, this was a mixture of oligomers of cleaved THF.
After oxidation of АNd with dry air, only THF and slight
amounts of benzene were found in volatile products. The
evolution of H2 in the hydrolysis of А may indicate the
presence of Ln—H groups. To confirm this assumption,
the product АDy was made to react with Et3GeBr. Previꢀ
ously, we found11 that lanthanide hydride complexes
LnH2(THF)3 (Ln = Sm, Eu, Yb) readily reduce triethylꢀ
germanium bromide to give Et3GeH. The products of
reaction of Et3GeBr with А were found to contain
triethylgermane, which confirms the presence of Ln—H
groups in the compound.
The cleavage of the solvent by iodides 1 and 2, which
proceeds with remarkable ease in the presence of the
aboveꢀmentioned aromatic compounds, cannot be exꢀ
plained by a direct reaction between LnI2 and THF beꢀ
cause without additives, solutions of these salts can be
stored under the given conditions for 24 h without noticeꢀ
able changes. At room temperature, they lose color after
5—7 h due to the reaction of LnI2 with the ether group of
the solvent, resulting in slightly colored products such as
ROLnI2.2 It is also unlikely that the sharp increase in the
reducing capacity of 1 and 2 in the presence of benzene
and other similar substrates is related to a change in the
reduction mechanism from innerꢀsphere to outerꢀsphere,
which is proposed in some cases for interpreting the reacꢀ
tivity of SmI2.13 In our opinion, the unusual behavior of
NdII and DyII diiodides in solutions is due to the ability of
lanthanide halides to exist as two forms, neutral LnXm
and ionic {[LnXm+1]–[LnXm–1]+} forms. In the case of
trivalent lanthanide salts, the existence of both the LnX3
and {[LnX4]–[LnX2]+} forms has been proved reliably by
Xꢀray diffraction data for dozens of compounds (see, for
example, Ref. 14). The reactivity and the catalytic activity
of compounds were found to be related to the structures
of molecules.14b,e In solutions, the two forms are in equiꢀ
librium, which is confirmed by the formation of either
neutral or ionic salt, depending on the synthesis or isoꢀ
lation conditions.14e,f Only neutral structures of the
LnX2(solv.)x type are known for divalent lanthanides;1,3—5
however, it is reasonable to suggest that these salts, in
Thus, the elemental analysis, the IR spectrum, and
the products formed in reactions with H2O, O2, and
Et3GeBr indicate that substance А contains the LnI, LnH,
and LnR groups (R are monomeric or oligomeric fragꢀ
ments of cleaved THF) and coordinated THF. The
ratio of these groups corresponds to the composiꢀ

Reactions of NdII and DyII iodides
Russ.Chem.Bull., Int.Ed., Vol. 51, No. 10, October, 2002
1911
particular, diiodides 1 and 2, can also exist in solutions as
[LnI3]–[LnI]+ ion pairs.
2 LnI2
[LnI3]–[LnI]+
(1)
.
The coordinated solvent molecules are not shown in
reaction (1) for the sake of simplicity, although their parꢀ
ticipation in these processes is of crucial importance. Reꢀ
action (1) proceeds as transfer of the I– ion (i.e., the
iodine atom bearing an electron), between metal atoms.
However, one may suggest that transfer of an electron
alone, without a iodine atom can take place in the
{[LnI3]–[LnI]+} ion pair under certain conditions. This
transfer would give rise to two neutral products, namely,
LnI3 and an unusual metal(I) monoiodide LnI.
(SiMe3)2ꢀ1,3]2}2(µꢀC6H6)];16b and [LaI2(THF)3]2(µꢀ
C10H8).16c Thus, benzene and other noncondensed aroꢀ
matic compounds are involved in these reactions like a sort
of catalysts that promote the transformation of singleꢀelecꢀ
tron reducing agents 1 and 2 into twoꢀelectron reducing
agents LnI and the subsequent oxidation of these species by
the solvent.
The assumed pattern of transformations taking place
upon the addition of aromatic compounds to solutions of
1 or 2 in THF and DME allows one to interpret the
unusual change in the route of reaction of 1 with phenol
at lower temperatures. We found that at temperatures
of –5 to 0 °C, both iodides in THF solutions react
with PhOH in the same way to give the corresponding
PhOLnI2(THF)x phenoxides (x = 3, 4) in good yields.
However, at temperatures of –90 to –100 °C, the neodyꢀ
mium and dysprosium derivatives react along different
pathways. Whereas a solution of iodide 2 gradually loses
color (as observed at 0 °C, but very slowly), in the case
of 1, within several minutes after the addition of phenol,
the color of the mixture changes to darkꢀbrown and the
NdI3 precipitate is formed. On subsequent warmingꢀup to
room temperature, the solution color turns to lightꢀblue.
In this case, the diphenoxide (PhO)2NdI(THF)3 (yield
46%) and NdI3(THF)3 were isolated from the reaction
mixture together with PhONdI2(THF)4.
.
(2)
Apparently, the formation of highly stable triiodide
LnI3 (which is actually observed in many reactions inꢀ
volving NdI2, DyI2, and TmI2) apart from the metastable
LnI makes reaction (2) thermodynamically feasible. The
properties of monovalent lanthanide iodides are unꢀ
known;* however, it is reasonable to expect that they
would exhibit an exceptionally high reducing capacity
and, hence, a very low regioselectivity. In a THF/C6H6
mixture, an attack by LnI would be mainly directed at the
THF molecules, because they are incorporated in the
metal coordination sphere and, therefore, they are more
easily accessible. Due to the low regioselectivity, the
monoiodide attacks not only the most "reactive" C—O
bond but also the C—H and C—C bonds to give a number
of LnI(H)R type products, where R are fragments of the
THF molecule including H atoms or THF oligomers.
Apparently, partial exit of LnI from the reaction cage
results in benzene metallation to give LnI(H)Ph or
LnI(Ph)2.
Since without benzene the reaction of 1 or 2 with the
solvent occurs slowly to give the diiodide complexes like
ROLnI2,2 one can conclude that the role of the substrate
is to initiate generation of the iodides LnI. In our opinion,
an aromatic compound incorporated in an intermediate
like {[LnI3][C6H6][LnI]} provides the transport of an elecꢀ
tron from the [LnI3]– anion to the [LnI]+ cation. After
formation of neutral iodides LnI3 and LnI, the substrate is
liberated unchanged.
Note that a number binuclear lanthanide complexes
with a bridging aromatic ligand have been reported,
for example, [K([18]ꢀcrownꢀ6)(η2ꢀC6H6)2]{[La{C5H3ꢀ
But2ꢀ1,3}2]2(µꢀC6H6)},16a [K([18]ꢀcrownꢀ6)][{Nd[C5H3ꢀ
The reaction of 1 with ButOH is accompanied by
gradual decoloration, irrespective of the temperature, and
affords only the monoalkoxide ButONdI2(THF)4.
In terms of the proposed set of reactions of 1 or 2 with
aromatic hydrocarbons (reactions (1)—(3)), the change
in the reaction pathway upon a decrease in the temperaꢀ
ture, found for the reaction of 1 with phenol, can be
explained by switching of the attack by NdI2 from the OH
group (at 0 °C) to the Ph group (at –90 °C). Apparently, a
decrease in the temperature has virtually no influence on
the formation of the reactive complex of the diiodide with
the benzene ring {[NdI3][C6H5OH][NdI]}. This also does
not influence the subsequent intramolecular electron
transfer or reactions of the generated NdI monoiodide
with the solvent and the phenol OH group, but sharply
decelerates the direct reaction between the same OH
* Previously,15 the formal oxidation state 1+ for Group III metꢀ
5
als was found only for scandium in the [(η ꢀBut2P3C2)Sc]2(µꢀ
6
6
η :η ꢀBut3P3C3) complex prepared by cryogenic synthesis from
Sc vapors and ButC≡P.

1912
Russ.Chem.Bull., Int.Ed., Vol. 51, No. 10, October, 2002
Bochkarev et al.
formation of carbides upon their combustion, the data of elꢀ
emental C,H analysis are poorly reproducible; therefore, the
compounds obtained were analyzed only for metal and iodine by
complexometry.
group and the NdI2 diiodide. The formation of the
(PhO)2NdI(THF)3 diphenoxide observed at low temperaꢀ
tures is, apparently, due to two processes, namely, the
reaction of phenol with the generated NdI monoiodide
and the reaction of phenol with the [NdI(H)R(THF)x]
complexes, resulting from cleavage of THF according to
the scheme given above. The reaction of 1 with tertꢀbutyl
alcohol involves no aromatic compounds; therefore, NdI
is not formed and no brown coloring or NdI3 precipitate
appears.
When dysprosium iodide 2 reacts with phenol, no inꢀ
termediate {[DyI3][C6H5OH][DyI]} complex seems to
form either at 0 °C or at low temperature, as indicated by
the absence of the DyI3 precipitate or the typical brown
coloring of the reaction mixture. The PhODyI2(THF)4
phenoxide, which results from singleꢀelectron reduction
of phenol, is formed in this case in 96% yield. The reacꢀ
tion of TmI2 follows a similar pathway.10а
Thus, the reduction of substrates with NdII and DyII
iodides can be either a singleꢀelectron or a formally twoꢀ
electron process. Upon the addition of noncondensed
aromatic compounds, characterized by low electron afꢀ
finities, to solutions of 1 or 2 in THF, the reduction
mechanism switches to the twoꢀelectron version and the
reducing capacity of the iodides sharply increases. Comꢀ
pounds of the R2LnI type become the major reaction
products. The assumption that diiodides 1 and 2 exist in
solutions in the ionic form [LnI3]–[LnI]+ provides an
interpretation for specific chemical properties of these
salts. The electron transfer from the anion to the cation,
which occurs under certain conditions, results in the genꢀ
eration of LnI monoiodides. The reduction potential of
these species, as indicated by their reactions with the
solvent, exceeds substantially those of alkali metals.
The LnI2 diodides (Ln = Nd, Dy) were prepared by burning
a mixture of lanthanide metal with iodine according to a previꢀ
ously developed procedure.2 Previously, we found that the preꢀ
cipitate left after the extraction of the combustion products with
tetrahydrofuran or dimethoxyethane, which consists of LnI2,
LnI3, and excess metal, affects appreciably the stability and the
reactivity of the resulting solutions. Therefore, prior to the addiꢀ
tion of substrates, solutions of 1 and 2 were centrifuged and
decanted from the insoluble fraction at –30 °C. The amount of
the diiodide taken in the reaction was found as the difference
between the weights of LnI2 before and after solvent extraction
followed by drying the precipitate in vacuo at 100 °C.
Reaction of the diiodide 1 with benzene. Benzene (0.1 g,
1.28 mmol) was added at –20 °C to a violet suspension of ioꢀ
dide 1 (0.632 g, 1.51 mmol) in 40 mL of THF. Over a period of
5 min, the color of the mixture changed to darkꢀbrown, comꢀ
pound 1 completely dissolved but a lightꢀblue NdI3(THF)3 preꢀ
cipitate appeared (0.448 g, 0.604 mmol). Gas evolution was
noted. After 30 min, the mixture was centrifuged, the solution
was separated from the precipitate, and the solvent together
with volatile products was removed by vacuum condensation.
GLC and 1H NMR analyses of the volatile products showed the
presence of only THF and benzene (0.081 g, 81%). The brown
waxy material left after the removal of the volatile products was
dissolved in 5 mL of THF and 15 mL of hexane were added. The
brown precipitate was separated from the mother liquor by cenꢀ
trifuging and dried in vacuo to give 0.45 g of brown pyrophoric
powder А, µ 3.4 µ (293 K). IR (Nujol), ν/cm–1: 1340 m,
eff
B
1250 m, 1180 m, 1150 w, 1070 m, 1010 s, 910 m, 860 s, 850 sh,
650 m. According to complexometry, substance А contained I
(25.90%) and Nd (31.03%) and also THF (GLC, after hydrolyꢀ
sis) in a THF/Nd ratio of 2.06 (for NdI(THF)3, calculated (%):
I, 26.03; Nd, 30.63).
Reaction of 2 with benzene. Under conditions described in
the previous procedure, benzene (0.312 g, 4.0 mmol) was
added to iodide 2 (1.06 g, 2.55 mmol) in 40 mL of THF to
give DyI3(THF)3 (0.97 g, 1.28 mmol) and a brown solid АDy
(0.625 g), containing 36.93% dysprosium and 28.84% iodine
(for DyI(THF)2, calculated (%): Dy, 37.48; I, 29.27). GLC
analysis of volatile products showed the presence of 0.28 g (90%)
of benzene.
Hydrolysis of product A(Nd). A 90% aqueous solution of
methanol (2 mL) was added to neat compound АNd (0.776 g).
Vigorous evolution of H2 was observed (24 mL, 1.07 mmol;
identified by GLC). The resulting suspension was centrifuged
and the solution was separated from the precipitate. The preꢀ
cipitate was washed with THF and dried in vacuo to give 0.675 g
(1.39 mmol) of NdI(OH)2(THF)2.5. Found (%): I, 27.90;
Nd, 29.03. C10H22INdO4.5. Calculated (%): I, 26.14; Nd, 29.71.
The removal of the volatile products by vacuum condensation at
100 °C left a brown resinous material (0.01 g). 1H NMR
(CDCl3), δ: 5.36 (br.s, 4 H, CH); 4.96 (br.s, 4 H, CH); 3.69 (t,
2 H, CH2); 3.24 (t, 2 H, CH2); 2.19 (s, 6 H, CH2); 2.03 (br.s,
18 H, CH2); 1.59 (br.s, 42 H, CH2); 1.27 (s, 42 H, CH2); 0.88
(m, 18 H, CH2). GLC analysis of the volatile products showed
the presence of THF (0.113 g, 1.57 mmol), benzene (9 mg,
0.1 mmol), and traces of four unidentified compounds.
Experimental
All operations on the synthesis and isolation of compounds
were carried out in vacuo using standard Schlenk equipment.
Solutions of 1 and 2 were transferred into reaction vessels through
glass connecting tubes, their contact with rubber tubes being
avoided. The solvents, THF and DME, were refluxed over NaOH
and over sodium metal and, finally, immediately prior to use,
they were kept for 15 min over 1 or 2. From the resulting soluꢀ
tions of iodides, the solvent was fed to the reaction vessel by
vacuum condensation. Commercial benzene, toluene, ButPh,
diphenyl, stilbene, hexane, diethyl ether, cyclohexane, and
silazane were purified by known procedures and dried at the
final stage over a sodium mirror. The reagents Et3GeBr, Et3GeH,
Ph2Hg, and Ph4Sn were synthesized by known procedures.17—19
Infrared spectra were recorded on Specord M80 and Perkin
Elmer 577 instruments; the samples were prepared as mineral oil
mulls. NMR spectra were recorded on a Bruker DPX 200 instruꢀ
ment. The GLC analysis of volatile products was performed on a
Tsvetꢀ530 chromatograph. Magnetic measurements were carꢀ
ried out at room temperature as described previously.20 Due to
the instability of organolanthanide compounds in air and the

Reactions of NdII and DyII iodides
Russ.Chem.Bull., Int.Ed., Vol. 51, No. 10, October, 2002
1913
Oxidation of АNd with air. A 40 mLꢀtube containing ANd
(207 mg) was carefully filled with dry air at –20 °C. The brown
powder А immediately turned into a lightꢀyellow waxy product.
According to GLC, the volatile products separated from the
reaction mixture by vacuum condensation at 100 °C contained
THF (23 mg), benzene (0.5 mg), and three unidentified comꢀ
pounds (total amount 0.5 mg).
warmingꢀup, the mixture gradually decolorized and, after
completion of the reaction, the solution became lightꢀstrawꢀ
colored. Compound 2 completely dissolved and PhODyI2(THF)3
precipitated as a colorless finely crystalline solid, which was
separated from the solution by decantation, recrystallized from
THF, and dried in vacuo at room temperature. Yield 0.5 g (97%);
m.p. 110 °C (dec.). IR (Nujol), ν/cm–1 : 3050 m, 1590 m, 1295 s,
1210 s, 1160 m, 1070 w, 1010 s, 910 m, 860 s, 770 s, 695 m,
560 m. Found (%): I, 35.60; Dy, 21.97. C18H29I2DyO4. Calcuꢀ
lated (%): I, 34.98; Dy, 22.39.
Reaction of ADy with Et3GeBr. Bromo(triethyl)germane
(0.55 g, 2.3 mmol) was added to a suspension of ADy (1.0 g) in
1 mL of THF. The mixture was stirred for 10 h at ∼20 °C and the
precipitate was separated by centrifuging. GLC analysis of the
solution showed the presence of 132 mg (36%) of Et3GeH.
Reaction of 1 with phenol at 0 °C. A solution of phenol (0.19 g,
2.0 mmol) in 10 mL of THF was added with stirring at 0 °C to
iodide 1 (0.738 g, 1.85 mmol) in 30 mL of THF. The precipitate
of 1 immediately dissolved and the color of the mixture changed
from violet to lightꢀblue. Gas evolution was observed. The soluꢀ
tion was concentrated to 15 mL and allowed to stand for 12 h at
–12 °C. The resulting lightꢀblue crystals were separated by deꢀ
canting off the mother liquor, washed with 10 mL of cold
THF, and dried in vacuo at ∼20 °C to give 0.597 g (41%) of
Reaction of 1 with tertꢀbutanol. A solution of ButOH (0.41 g,
5.53 mmol) in 15 mL of THF was added at 0 °C to iodide 1
(3.01 g, 3.97 mmol) in 50 mL of THF. After 15 min, the reaction
was over and the mixture acquired a lightꢀblue color. The soluꢀ
tion was concentrated to 10 mL and cooled to –15 °C. The
lightꢀblue crystals of ButONdI2(THF)4 (2.33 g, 77%) formed
after 10 h were separated by decantation, washed with cold
THF, and dried in vacuo; m.p. 94—95 °C. IR (Nujol), ν/cm–1
:
1070, 1040, 1000, 900, 870, 840 (sh). Found (%): I, 32.94;
Nd, 18.57%. C20H41I2NdO5. Calculated (%): I, 34.41;
Nd, 18.99.
PhONdI2(THF)4; m.p. 140—145 °C (dec.). IR (Nujol), ν/cm–1
:
This work was financially supported of the Russian
Foundation for Basic Research (Project No. 00ꢀ03ꢀ32875)
and the U.S. Civilian Research & Development Foundaꢀ
tion for the Independent States of the Former Soviet
Union (CRDF, Project RClꢀ2322ꢀNNꢀ02). The authors
wish to thank S. Ya. Khorshev and T. G. Mushtina for
recording and interpreting the IR spectra.
3050 m, 1600 m, 1500 s, 1490 s, 1270 s, 1070 w, 1030 s, 910 m,
870 s, 770 m, 700 m, 590 m. Found (%): I, 32.02; Nd, 18.87.
C22H37I2NdO5. Calculated (%): I, 32.56; Nd, 18.50. Hexane
(20 mL) was added to the mother liquor. The precipitate thus
formed (0.51 g, 35%) was washed with hexane and dried in
vacuo. The iodine and neodymium contents, the IR spectrum,
and the decomposition point of the precipitate were identical to
those presented above for PhONdI2(THF)4. The total yield was
1.107 g (76%).
References
Reaction of 1 with phenol at –100 °C. A suspension of ioꢀ
dide 1 (0.59 g, 1.48 mmol) in 20 mL of THF was cooled to
–100 °C, and phenol (0.16 g, 1.70 mmol) was added. After
3 min, the violet color of the mixture changed to brown. Slight
gas evolution and precipitation of grayishꢀblue NdI3 were obꢀ
served. The mixture was heated to room temperature; as this
took place, the solution gradually became lightꢀblue. After setꢀ
tling, the solution was decanted from the precipitate. By vacuum
condensation of the solvent, the solution was concentrated to
10 mL and cooled to –12 °C. After 2 days, the precipitated blue
crystals of (PhO)2NdI(THF)3 were separated. Yield 0.229 g
(46%). After recrystallization from THF, the substance melted
with decomposition at 145 °C. IR (Nujol), ν/cm–1: 3050 m,
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Received April 4, 2002;
in revised form June 18, 2002