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Binuclear Complexes of Chromium and Molybdenum with Ethylenebis(diphenylphosphine) as Bridging Ligand.

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of 50-100 mesh). Most silaceous ion exchangers are less
suitable on account of their lower resistance to acids and
bases.
Inorganic redox ion exchangers are obtained by loading
either zirconium oxide hydrate gel with aqueous solutions
of phosphite, dithionite, thiosulfate, sulfite, dichromate, permanganate, o r oxalate, or zirconium phosphate gel with
hydrazinium, hydroxylammonium, iron(II), iron(III), cerium(ITI), or cerium(1V) ions (see Table).
Capacity [a]
Charging
solution
Ion
Concn.
1
Time (niin)
(ineq/g) half
p~
I totally
charged
a) Zirconium oxide hydrate gel
Dithionite
Phosphite
Sulfite
Thiosulfate
Dichromate
Permanganate
Oxalate
1N
1N
1N
1N
0.1 N
0.8 N
0.1 N
I N
7.0
6.2
9.4
0.8
1.2
1.4
6.2
0.75
3.9
3.7
6.3
6.2
0.97
2.5
0.36
1.4
1.5
70
2.5
90
2.5
120
0.5
9
35
480
-
~
1.0
3
12
120
b) Zirconium phosphate gel
Hydrazinium
1N
Hydroxylanimoniuni I N
0.1 N
Iron(l1)
I N
Iron(Il1)
Ceriuni(I1l)
Ccrium(1V)
0.1 N
I N
0.1 N
0.1 N
3.9
2.8
In I N H2S04
In IN H 2 S 0 4
In I N HzS04
In 1N HzSOA
In 1N H2S04
In 1N H2S04
1.6
1.1
0.06
0.13
0.78
2.1
0.06
0.87
0.2
0.2
0.5
0.5
15
60
0.5
40
4
By Dr. H. Werner, R. Prinz, E. Bundschuh, and
K. Deckelmann
Anorganisch-Chemisches Laboratorium,
Technische Hochschule Miinchen (Germany)
Chromium and molybdenum hexacarbonyls (f) react with
ethylenebis(dipheny1phosphine) (abbreviated PP) to give
chelate complexes (2) in which the two phosphorus atoms of
the diphosphine are coordinatively linked to the same metal
atom [ZJ. Kinetic studies [31 show that these reactions occur
by an SN 1 dissociation mechanism. If, however, a carbony1
(f) is treated with ethylenebis(dipheny1phosphine) in a
molar ratio 2 : l under mild conditions, binuclear complexes (3) are formed in which the diphosphine functions as
bridging ligand and links two M(CO)5 residues formed as
primary dissociation products of (I). After 20 hours in
boiling dioxane, the yield of complex ( 3 ) , M = Cr, amounts
to 55 :<; for M = Mo it is 63 % after 4 hours' heating in a
1 : 1 mixture of dioxane and tetrahydrofuran. The complex
(3) can be freed from the compounds (2) formed as byproduct by chromatography o n neutral alumina and recrystallization from toluene. Compound ( 3 ) , M = Cr forms
pale yellow needles, m.p. 200-201 "C; compound ( 3 ) , M =
Mo forms colorless crystals, m.p. 192-- I94 "C.
4
2
2
120
600
2
1800
[a1 0.5 6 of support was shaken with 50 ml of charging solution until
equilibrium was attained, and the bound ions were determined radiometrically or by redoxtitration.
The zirconium oxide hydrate gel is an amphoteric, the
zirconium phosphate gel a weakly acidic, bifunctional ion
exchanger. Sometimes the zirconium and phosphate ions in
the support react irreversibly with ions in the charging
solution. For this reason, the exchanger capacities found are
much more dependent upon the experimental conditions
than they are with organic ion exchangers. For example,
zirconium oxide hydrate gel exhibits a strong p H dependence
in its capacity for chromate and dichromate ions. At p H 1.0,
the capacity is 1.4 meq,'g but at pH 10.5 only 0.15 meqlg.
Again, zirconium phosphate gel has a capacity of 7.5 meqig
for hydrazinium ions at p H 7.5 and a capacity of about
5 meqlg for hydroxylammonium ions at p H 5.5.
The high capacities, as well as the cotme of the loading reaction with time seem to indicate a precipitation of iron(II1)
on the zirconium phosphate matrix and complex formation
of oxalate with the zirconium oxide hydrate support. Complex formation probably also occurs between hydrazinium
and hydroxylammonium ions and zirconium phosphate
supports.
Very strong oxidizing agents attack organic ion exchange
resins. Consequently the cerium(IV)/zirconium phosphate
and permanganate and dichromate/zirconium oxide hydrate
systems are the first stable redox exchangers with extremely
high redox potentials.
Received: April 28th, 1966
[ Z 221 IE]
German version: Angew. Cheni. 78, 645 (1966)
~~
[ I ] Redox ion exchangers, Part XII1. - Part X11: 8.Scrnsoni and
0 . Si,qinund, Angew. Chem. 74, 695 (1962); Angew. Chern. internat. Edit. I, 554 (1962). The investigations were supported by the
Bundesministeriumf u r wissenschaftliche Forschung (St. Sch. 161).
[2] Present address: Radiochemisch-analytische Gbteilung, Institut f u r Strahlenschutz, Gesellschaft fur Strahlenforschung
mbH., SO42 Neuherberg bei Miinchen (Germany).
606
Binuclear Complexes of Chromium and
Molybdenum with Ethylenebis(dipheny1phosphine)
as Bridging Ligand
Proof of the structure of compounds (3) is based on elemental analyses, molecular-weight determinations (in CHC13 and
C&), and infrared spectra. The vco bands of (3) for M = Cr
are a t 2065, 1984, 1943, and 1933 cm-1; those for M = Mo
at 2073, 1990, 1952, and 1939 cm-1 (in CCI4).
The binuclear complexes (3) react with further ethylenebis(diphenylphosphine), giving the chelates (2). The kinetics of
these reactions can be followed by means of the infrared
spectra. The results collected in the Table show that the
reaction rate in toluene or dioxane is proportional to the
concentration of (3) and independent of that of the diphosphine.
On boiling tolvenc)
I:?
1.10
1:20
I .OR
1.17
I .05
hl
Mo
(in boiling toluenc)
I:?
1.10
5.58
M
Cr
M
210
(in boiling diohane)
5.42
I:20
5.81
I:2
1:20
1:40
2.14
2.73
2.16
It fo!lows that this substitution reaction is also governed by an
sN1 mechanism. The rate-determining step is probably the
splitting of a metal-phosphorus bond. The coordinatively
;
?
:J
PPM(CO)I, r M ( C 0 ) j
14;
(51
1 41
I'P
-->
14)
4
(2)
Angew. Clteni. internot. Edit.
~
(5)
co
i Vol. 5 (1966) 1 No. 6
unsaturated intermediate (5) reacts with the diphosphine in
a second, rapid step, giving an intermediate (4) which forms
the chelate with loss of CO.
Received: May 12th, 1966
[Z 230 IE]
German version: Angew. Chem. 78, 646 (1966)
~~
.
A solution of ally1 isocyanate (20 g) and AIBN (1
bromotrichloromethane (200 g) is refluxed for 3 hr
steam bath. Evaporation of the excess of BrCCI3 gives
product ( l ) , which is distilled at 92-94OCi0.5 mm.
80 %, colorless oil, n2,a = 1.5269.
g) irr
on a
crude
Yield
--
[ I ] I<inetic Studies of Substitution Reactions of Metal Complcxcs, Part 4. - Part 3 : H . Werner and R. Prinz, Chem. Ber., in
press.
CHz-=CH--CH?-NCO + BrCCIS
->
[2] J . Chat? and H . R . Watson, J . chem. SOC.(London) 1961,
4980; F. Zingules and F. Canziuni, Gazz. chim. ital. 92, 343
( I 962).
[ 3 ] H . Werner and R. Prim, Angew. Chem. 77, 1041 (1965);
Angew. Chem. internat. Edit. 4 , 994 (1965); H . Werner, J. organomet. Chemistry 5 , 100 (1966).
Free-Radical Initiated Addition of
Bromotrichloromethane to Ally1 Isocyanate
By Dr. W. J. Farrissey, Jr., F. P. Recchia, and
Dr. A. A. R. Sayigh
The Upjohn Company. Carwin Research Laboratories,
North Haven, Connecticut (U.S.A.)
The addition of radical species to ally1 isocyanate has
previously not been examined. We have now found that
bromotrichloromethane undergoes rapid addition to the
C = C double bond in the presence of azobisisobutyronitrile
(AIBN) to form 2-bromo-4,4,4-trichlorobutyl isocyanate ( I ) .
CI3C-CH2-CHBr-CH:
NCO
i 1)
The N M R spectrum[ll of (1) comprises two doublets at
3.38 and 3.83 ppm (2 CH2 groups) and a 5-peak multiplet
at 4.45 ppm (CH group).
With methanol, ( I ) gives the urethane, m.p. 64-65.5"C;
with p-toluenesulfonamide in refluxing toluene it gives the
urea derivative, m.p. 185-186 'C.
With stoichiometric quantities (or less) of BrCC13 in the
synthesis of ( 1 ) the yield decreases and the amount of less
volatile material increases. Presumably telomerization occurs,
since the isocyanate function remains intact.
With CC14 in the presence of AIBN or benzoyl peroxide,
ally1 isocyanate reacts primarily at the isocyanate group.
Received: April 26th, I966
[Z 229 IEI
German version: Angew. Chem. 75, 616 (1966)
[ I ] Varian A-60 spectrometer; chloroform solution with tetramethylsilane as internal standard.
CONFERENCE REPORTS
Macromolecular Colloquium
This colloquium was held on March 3rd-5th, 1966, at the
Institut fur Makromolekulare Chemie der Universitlt Freiburg (Germany).
Studies of the Thermal Dehydrochlorination of
Poly(viny1 chloride)
D . Brriiin and M . Thallmaier, Darmstadt (Germany)
I n spite of numerous studies of the thermal removal of
hydrogen chloride from poly(viny1 chloride) (PVC), the
positions in the macromolecule responsible for initiation of
this reaction have hitherto remained obscure. To test the
effect of irregularities in structure of the PVC chains on
thermal decomposition, we have investigated the dehydrohalogenation of copolymers of vinyl chloride with small
amounts of diethyl fumarate (DEF), isobutene (IBu), vinyl
bromide (VBr), and 2-chloropropene (2-CP). The rate of
thermal dehydrohalogenation of the copolymers with VBr
and 2-CP between about 100 and 140 "Cis proportional to the
square of the mole fraction of these units in the copolymers;
it can thence be shown that the rate is proportional to the
mole fraction of those VBr or 2-CP units which are present
in sequences of two or more units. It follows that under the
experimental conditions used the liberation of a molecule of
hydrogen halide from an isolated, thermally labile structural
unit does not initiate further loss by a "zip" mechanism.
Longer polyene sequences arise only if loss of a second
molecule of hydrogen halide is possible owing to the neighboring presence of a second labile unit, or o n use of higher
temperatures. The significance of these results for the
mechanism of thermal removal of HCl from poly(viny1
chloride) and for the mode of action of heat stabilizers was
discussed.
Aiigew. Chem. internat. Edit.
/
Vol. 5 (1966) 1 No. 6
The polyene sequences arising on thermal decomposition can
be analysed by means of their electronic spectra. The regularities in polyene spectra permit approximate establishment of the distribution of polyene sequence lengths in PVC
and poly(viny1 bromide) (PVBr), and in vinyl chloride-DEF
and -1Bu copolymers. In degraded PVC, the frequency of
occurrence of sequences decreases continously with increasing
number of conjugated double bonds; in degraded PVBr,
oolvene seauences with a mean of 12 to 13 double bonds are
-~
commonest. For PVC, the ratio of the total number of
polyene sequences to the amount of HCI liberated decreases
with increasing time of degradation, i.e. with increasing
removal of HCI; the frequency distribution is shifted in
favor of shorter sequences, a result attributed to preferential
disappearance of the longer polyene sequences by secondary
reactions.
Solution Properties of Polyvinylpyrrolidone
W . Burchard, Freiburg (Germany)
Light-scattering measurements on polyvinylpyrrolidone(PVP)
in several solvents and in mixtures of solvent and precipitant show that the radius of gyration is clearly dependent
on the composition of the @-solvent (change of conformation). The change of one conformation into another is,
however, initiated far above the O-point by a relatively
small amount of precipitant. The conformational change is
particularly marked for aqueous solutions to which acetone
or dioxane has been added. Acetone causes expansion of the
coil, dioxane a contraction; ihese effects are not due to
intermolecular interactions. The conformational change is
cxplained as being due to preferential solvation of certain
groups in the macromolecule.
607
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binucleata, diphenylphosphino, bridging, complexes, molybdenum, ethylenebis, ligand, chromium
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