γ-Rhenium(IV) chloride, dirhenium octachloride-hexachloropropene, rhenium(IV) bromide

INORG.

NUCL.

CHEM.

-RHENIUM(IV)

LETTERS

Vol. 8,

pp. 413-415,

19"/2. Pergamon Press.

Prinled in Oreat Britain.

CHLORIDE, DIWHENIU~ OCTACHLORIDE-HEXACHLOROPROPENE, RHENIUm(IV)

BROMIDE

H. MUller and R. Waschinskl ( Chemical Laboratory,

University,

D-78 Freiburg, Germany )

~Received 20 January 1972)

Dark red dlrhenium octachlorlde-hexachloropropene Re2C18"HCP can be prepared with a yield of 70 - 90% by the reaction of rhenium pen~achloride,

rhenium heptoxlde

and rhenium oxide tetrachloride,respectively, hexachloropropene

wlth

( HCP ) ( 4 - 6 h, 160 - 180 °C )

( Re found 41.1%, calcd. 41.3% ). Re2C18"HCP is also produced by the reaction of amorphous rhenium dioxide hydrate ( obtained by hydrolysis of rhenium pentachloride hexachlororhenium(IV)

or

acid ) with HCP ( 2 - 6 h, 160 - 180°C,

yield ca. 75% ). Unidentified products of varying composition have been obtained if the oxide contains much water and/or if little HCP is used.No reaction was observed between HCP and rhenium trichloride,

crystalline monoclinic rhenium

dioxide (I) or rhenium trioxide, respectively. Re2C18"HCP loses at 140 °C and high vacuum one mole of HCP ( loss found 27.2%, calcd. 27.5% ); the remaining substance proves as a new not yet known modification of rhenium(IV)

chloride,

C1 found 45.O%,calc~. of Re2CI~'HCP ~uto

~-ReC14 ( Re found 56.8%,calcd. 45.2~ )

Y-~eC]~

(2,3,4,5,6).

56.8%;

The decomposition

c~n be carried out incompletely

413

y-ReC14, Re2CI8 "HCP, ReBr4

414

by refluxing with carbon tetrachloride.

Vol. 8, No. 4

Brown

~-~eC14 is

obtained directly with a yield of ca. 75% by the reaction of rhenium pentachloride

with tetrachloroethylene

( 6 - 24 h ,

120 - 140 °C ) ( Re \ found 56.8%, C1 found 42.9% ). At higher temperature and/or extended reaction time 5-ReC14 is produced, in some cases even rhenium trichloride was obtained. In a recent communication by Cotton about the preparation of rhenium tetrachloride

from rhenium pentachloride and carbon tetra-

chloride/tetrachloroethylene

nothing is said about which

modification was formed (7).

y-~eC14 reacts back with HCP

at 160 - 180 °C ( 4 - 6 h ) to ~e2C18"HCP , under which conditions 5-ReC14 is unaffected. Attempts to prepare single crystals of

7-ReC14 have been

without success. Transport reaction experiments with rhenium pentachloride,

bromine and iodine,

respectively,

in the

temperature range 150 - 250 °C and heating with tetrachloroethylene in sealed ampoules ( 16 h, 170 °C ) only resulted in the formation of ~-ReC14. Following Visser's method (8) powder Guinier diffraction photographs could be indexed on the basis of a monoclinic

cell with the parameters a = 18.43 A;

b = 6.27 A; c = I~.17 A; 5 = 104.O °. The observed density of the poorly crystallized

~-ReC14 was 3.99 g/cm3,the

calculated densfty was 4.277 g/cm 3 for z = 16 . Black rhenium tetrabromide is formed by the reaction of rhenium pentachloride with boron tribromide

( 1OO °C, 5 d )

( Re found 37.0%, calcd. 36.8%; Br found 62.2%, calcd. 63.2% ). The observed density is 5.47 g/cm 3.

y-rhenium tetrachloride

and rhenium tetrabromide yield very similar X-ray diffraction photographs an~ are probably isostructural.

Vol. 8, No. 4

y-ReC14, Re2CI8 "HCP, ReBr4

415

All experiments were accomplished in the usual way under exclusion of oxygen and water. After filtration the reaction products were washed with carbon tetrachloride. These investigations have been supported by the Deutsche Forschungsgemeinschaft.Computer

calculations have been

performed by the Freiburger Rechenzentrum.Thanks to Dipl. Phys. C.-D. Carpentier,

are due

Institute of Crystallography,

for help with the program and discussions.

References

(i)

P. Gibart, Bull. Soc. Chim. France 1964, 70

(2)

D. Brown and R. Colton, Nature(London)

(3)

I.R. Anderson and J.C. Sheldon,

198, 1300 (1963)

Inorg. Chem. 2, 2602 (1968)

(4)

M.J. Bennet, F.A. Cotton, B.M. Foxman and P.F. Stokely, J. Amer. chem. ~oc. 89, 2759 (1967)

(5)

J.H. Canterford and R. Colton, Inorg. Nucl. Chem. Letters ~, 607 (1968)

(6)

P.W. Frais, A. Guest and C.J.L. Lock, Can. J. Chem. 47, 1069 (1969)

(7)

A. Brignole an~ F.A. Cotton, Chem. Comm. 197 I, 706

(8)

J.W. Visser, J. Appl. Cryst. ~, 89 (1969)