On the cyclooctatetraenyl compounds of actinide elements part II. Bis-(cyclooctatetraenyl) protactinium(IV)

INORG.

NUCL

(IH~l.

LETTERS

Vol. 10,

pp. 413-419, 1974.

Pergamon

Press.

Printed

in

Great

Britain.

0n the Cyclooctatetraenll Compounds of Actinide Elements Part II. Bis-(cyc~octatetraen~l) protactinium(IV) GOFFART J. ~, FUGER J., BROWN D. ~nd DUYCKAERTS Go Institute of Radiochemistry, University of Li6ge, S;rt Ti]mccl B - 4000 LIEGE (Belgium) (Received 31 January 1974)

ABSTRACT The preparation reported.

of o new organometa!lic

It has been characterized

powder diffraction

compound,

(CsHs)2Pa , is

by IR spectrometry

~nd by X-r~y

analysis.

INTRODUCTION Compounds

of actinide

iigand have been reported and plutonium (CsH8)2Pa.

(iV) I'2.

elements

with cyelooctatetraene,

for thorium

(IV), uranium

We have now succeeded

Only one other organometallic

(C8H8) , :z<;

(IV), neptuniun

in synthesizing

compound

(IV)

the compound

of protactinium,

(CsHs)4Pu , has previously 3 been characterized.

EXPERIMENTAL Reagents specie! refluxed

: All experiments glove-box.

were carried out under purified

Solvents

Protactinium and purified

tetrachloride

by sublimation

sium salt was made according drofuran

were purified by conventional

and distilled in the presence

argon in =~ methods~

of (CsHs)2U.

was prepared

in vacua.

as described

Cyclooctatetraenyl

to the literature

previously 4 dianion !)otas -

preparation 2 i:l tetr:~hy-

(THF) .

Preparative

: (C8118) 2 Pa was prepared

PaCI 4 + 2 C8H8K 2

* Charg@ de Recherches Nucl~aires ** Chemistry Division,

THF)

according

to the reaction

(CsHs)2Pa + 4 KCI

A l'Institut

Interuniversitaire

AERE, Harwell,

(I)

des Sciences

Great Britain

q P r e s e n t e d in Part by J . G O F F A R T at in A c t i n i d e C h e m i s t r y , Liege, M a y 413

the S y m p o s i u m 3-4, 1973.

on Recent

Aspects

414

CYCLOOCTATETRAENYL COMPOUNDS

Vol. 10, No. 5

After stirring the reaction mixture for 10 hr or more, the solvent was removed under vacuum.

The compound w~s recovered by extraction into

toluene or by direct sublim:~tion from the residue of the evaporation. After r e s u b l i m a t i o ~ 1 5 5 °C, 5 10 -3 T), a ye!lowish-coloured product was obtained;

the final yield, based on PaC14 after two sublimations did not

exceed 1 % . Physical studies

: The infrared spectrum (Nujo] mu!] between KBr discs)

was recorded on a Perkin Elmer Infracord Spectrophotometer. The X-ray diffraction powder p~tterns of the samples sealed in vacuo (I0-5T) in very thin capillaries were obtained with a Philips unit, mode] PW 1010, using chromium X-radiation.

The camera was a 57.54 mm

diameter Philips Debye-Sherrer type (PW 1025/10) that employed Straumanis film mounting and w~s equipped with a 0.21 mm diameter brass micro~ollimator.

Exposure times ranged between 4 and 8 hours, operating

at 24 kV - 16 mA and using Industrial G films.

In some instances, a

vanadium filter was used to remove the chromium K~I radiation.

A number

of exposures, typically 1 hour at 38 kV - 26 mA were also obtained using a copper X-radiation fine focus tube, which resulted in a poorer line resolution than with the chromium radiation. Line positions on the films were determined by means of a micrometric ruler (Siemens-Kirem type 940) allowing an ultimate precision of O.O1 mm; duplicate measurements were averaged.

Corrections for film

shrinkage were made.

Intensities were estimated visually.

For lattice

parameter refinement,

the LCR-2 programme, written by Williams 5 was

used and the Nelson-Riley extrapolation function was applied.

In this

programme, e~ch indexed line is weighed by a factor proportional to i/sin2(2 @ ) . ~ 2 ( @ )

wherea. (@) is the estimated random error in @4~(@)

was assigned a value of 0.05 ° .

When an observed line was considered

to arise from the superposition of several theoretically-possible reflexions,

each reflexion in the group was assigned a value of

(@i) given by the relation ~(8~)

=

o.o

lj = n j : 1

(2)

Ii in which I. is the calculated theoretical intensity for the ithref!exion. l

Vol. 10, No. 5

CYCLOOCTATETRAENYL COMPOUNDS

415

Thus, for the entire group of n possible reflexions ~(0) e,:ua] to 0.05 °.

The theoreticaJ

line intensities

remoi~c

(scaled to I 0

~ =

10.0) used in this process were taken, as ~ first upproxim:?tion, from a calculation made by Dr. J.L. Burns (Transuranium Research LeboratoK

ry, Oak Ridge National Laboratory) with the sJd of the POWD progr:mme ~ for the thorium compound using the positional and ~uisotropic therm;~ p~r~.meters listed by Avdeev et a]7; in these c~!eul~tions,

~n absorption

correction for cylindrical samples was mt~de by me~nc of a subroutine built in the programme, using a w~.lue of Lr = ~.0 wlqere ~ is the [iine~,r absorptior~ coefficient and r the radius of the cylinder.

RESULTS AND DISCUSSION Analysis of X-ray powder diffrsction results has identified the ~roduct of the reaction between P~Ci 4 and CsH8K 2 as (CsHs)2P~ , which i:~ isostructur~l with the previously oharacterised uctinide

(IV) bis-

cyc~ooctatetraenyls and whici~ exhibits an infrared spectrum virtu~ L!y identical with those of its nnalogues.

The yield of (C8Hs)2P:~ is

appreciably lower than those obtained for other act!hide octetetraenyls under the same experimental conditions. cor~sequence of the fact that protactinium

(If) bis-cyc~oThis may be o

(IV) is oxidised much more

readily than the tetravalent states of thorium, ur~nium, neptunium and plutonium.

(Cf. the instability of, for example, Pa(dtc)4, dtc = N,N, --

diethyldithiocarbamate, relative to its actinide

7

8

(IV) analogues )o

Attempts to obt;~in (C8H8)2Pa using benzene at ambient temperature -~ the solvent for reaction I have been unsuccessful. compounds of this type,

Like the othe~ ~

(C8H8)2Pa is extremely sensitive to air and has

a very low solubility in common organic solvent. Details of the infrared spectrum of (CsHs)2P~ are given in T~b!e I together with those for the thorium, uranium and neptunium an log~es for comparison.

It is seen that the infrcred spectra of the ~ctiride

(IV) cyclooctatetraene compounds are essentially identical with r~i~ tively few sbsorption bands as expected for compounds of higi~ symmetry 9 .

416

CYCLOOCTATETRAENYL COMPOUNDS

TABLE

Infrared spectra

Vol. 10, No. 5

1

(cm -I) of (C8H8)2Act*

~- . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . !

I(CsH8 )2 Th

(CsH8 )2 Pa

695 vs

695 vs

698 vs

690 s

Asymmetric ring metal ring tilting

742 s

745 s

746 s

740 m

775 s

775 m

777 m

~C-H bending (I) and C-H bending (1) or C-C-C bending (I)

790 w

795 m

792 m

848 w 895 s

895

s

(CgH8 )2 U

845

w

900

s

1318 m

1310 m

1320 m

1765 w

1750 w

1765 w

1865 w

1850 w

1870 w

1965 w

(C8H8 )2NP 1

890

s

Assignment 9

C-H bending

(//)

C-C stretching

1960 w

*

vs

:

very strong;

s : strong;

m : medium; w : weak

A partial list of observed and calcultad 2e values is shown in Table II; the observed values are the sverage of values obtained from two photographs the monoclinic

of the same prepsration and the i~Sexing is based on (P21/n)

nium compounds °.

structure of the corresponding

With chromium radiation,

diffraction

thorium ~nd uralines could be

read up to a 2~ value of about 135 ° but due to the complexity of the pattern only those lines below 85 ~ have been indexed. no extraneous line was detected. p~rameters

(+ 2 ~ )

were obtained

Up to this angle,

From the data the following lattice :

a = 7.063 b = 8.825 c = 10.719 = 98.37

÷ ~ ~ ~

0.O10 A 0.011 O.01L~ 0.10 degrees

Vol. 10, No. 5

CYCLOOCTATETRAENYL

TABLE

Partial

COMPOUNDS

II

X-roy Powder Diffraction

Resu~ta

. . . (chromium r~Jdiation; K_a . °'2909~' .

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

; k I .

.

.

.

.

.

.

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.

.

.

.

.

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.

.

.

.

.

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.

.

.

.

.

.

.

2@cxlc" .

.

0 1 1~

.

.

.

.

.

.

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.

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.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

for (CsH8)2P:~

2.o848~"

KS l

.

.

.

.

.

.

.

.

.

.

.

.

.

2"I)01[..~:"

Icslc " .

417

.

.

.

.

.

.

.

.

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.

.

.

.

.

.

lob~, .

.

.

.

.

.

17.68

2.0

0 1 I

19.45

1 0 1

2Io06

] 0 i~ 1 1 0 {8

21.93 2 1 o94

0~6 i. 2

O 0 25

22.68

0.5

! 0 1 1 1 0

24.13 24.14

3.0 6.0

O O ~

24.95

2.5

24.9t

2.j~

0 2 0

30.09

1.2

30.02

i.',

i

32.88

2.3

32.82

5

1 I 2~ 1 2 I~

33.57 33.58

0.2 0.5

_

33.57

i

1 1 2 I 2 1

37.01 37.02

1.0 2°6

"1. ~

}7.05

2 0 0

38°28

1.0

0 2 2

39.48

! 0 3

39.90

0 1 3

40.86

1.3

40.82

~.5

1 1

41.53

1.4

41.48

1.5

2 1 1 1 0 3

44.98 45.15

1.7 1.2

O 3 1

47.67

1.8

2 0 2 2 2 0

49.43 49.44

1.2 1.4

! 3 0

49.98

- 1 2 3 0 0 4

-

-

-

I 2

-2

17.61

4

10.0

19.50

10

6.1

2~.06

5

.97

4

~

21

22.69 }

24.~I

0.5 I0

~: :18.25

I

0.6

39.61

0.5

1.1

39-93

0.9

}

45 Otl " 47.67

1.5

49"45

2

1.9

50.09

1

50.77

1.2

5.50.73

O.b

51.20

1.2

51.21

o.b

2 1 3 - 2 2 2

52.90 5~.26

I. I 1.7

53"19

3;

1 1 4

54.52

1.~

54.43

2

-

1 2 3 1 3 2

55 -21 55.23

1.3 1.6

--

55.21

5

1 3 2

58.06

-

3

~

b8.o6

o

1

58.41

1.4

0.4

} ~

~ ~

418

CYCLOOCTATETRAENYL COMPOUNDS

Vol. 10, No. 5

TABLE ll(cont) .

.

.

.

.

h .

.

.

.

.

.

.

k

.

.

.

.

.

.

.

.

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.

.

1 .

.

.

.

.

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.

.

.

.

.

.

"~

"'calc. .

.

.

.

.

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.

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.

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.

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.

* .

.

.

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.

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.

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.

.

.

.

.

.

"

Ic~!c. .

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

2 2 2

58.96

1.0

1 1 4 2 0 4

60.14 60.38

1.3 0.5

0 2 4

6o.54

1.0

3 1 0 2 1 3 2 3 1

61.14 6!.35 61.38

3 0 1 0 4 0

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

20obs. .

.

.

.

.

.

.

.

.

iobs. .

.

.

.

.

.

.

.

58.99

0.5

~

60.27

2.5

1.2 1.2 1.5

] ~

61.41

4

62.48 62.56

0.7 0.7

~

62.45

0.5

3 1 2

63.18

0.8

63.13

0.5

2 3 1

64.04

0.9

64.15

I

1 4 1 3 2 1

66.79 67.10

1.1 0.9

66.88

I

2 2 4

68.94

0.9

68.95

I

2 2 3 3

3 4 2 1

70.51 70.78 70.89 70.90

0.8 0.4 0.8 0.7

70.84

2

1 0 5 1 3 4

71.86 71.89

0.4 0.6

~

71.89

1

1 2 5 2 1 5

73.76 74.27

0.6 0.7

~

74.02

0.5

3 1 4 1 3 4 1 4 3

76.52 76.80 76.82

0.6 1.0 0.4

~

76.67

1

3 0 3 3 3 0 2 3 3

77.67 77.70 77.88

0.3 0.5 0.8

~

77.75

1

2 2 4 2 4 2

78.79 78.82

0.5 0.6

78.63

I

4 0 0 1 1 6 O 5 1

81.95 82.27 82.28

0.2 0.4 0.4

~

82.30

0.5

0 3 5 2 4 2

83.49 83.61

0.6 0.6

J

83.60

0.5

3 0 1 2

J

* B~sed on the lattice parameters given in the text, with a NelsonRiley extrapolation correction.

Low intensity lines which were

not observed experimentally were omitted from this column.

Vol. 10, No. 5

C Y C L O O C T A T E T R A E N Y L COMPOUNDS

419

With two formulae per unit cell, these values [!ead to ~ calculated density of 2.21 g cm -3, which is slightly lower than the w~lues of 2.22 and 2.29 g cm -~ ~ reported

6 , respectively,

thorium and ursnium compounds° r~diotion

Exposures

for the corresponding

t;~her with the copper X-

led e:;sentio.]~y to the s~me lattice p~r:~eter w~]ues, w~th

error limits c:~. 2.5 times !z~rger.

ACKNOWLEDGMENTS We th~nk tile Institut Interuniversitaire for financisl support. Research L~boratory,

de~ Sc'_enees

We thcmk ~lso Dr. J.L. Burns

Nucl@z~ires

(Tr~nsur<~nium

Osk Ridge N~.tion~! L~'bor:~tory) for pe~'forming the

intensity calculation.

REFERENCES I. D.G. KAR~IKER, J.A. STONE, E.R. JONES a~d N. E D E L S T ~ N , J. Am. Chem. Soc. 4841, 92, 1970 2. J. GOFFART, J. FUGER, B. GILBERT, B. KANELLAKOPULOS Inorg. Nuc!. Chem. Letters 403, 8, 1972 3. F. BAUMGARTNER, E.O. FISCHER, Angewo Chem. 182, _5, 1969

B. KANELLAKOP[~OS

u n d G.DUYCKAERTS

~r~d P. LAUBEREA]]

4. D. BROWN and F.J. JONES, J. Chem. Soc. (A) 719, 1967

5. D.E. WILLIAMS, Ames Lab. Report IS-I052

(1964)

6o D.K. SMITH, University of CaliforniT~, Lawrence BerkeTcy L~b. ReEort UCRL-7196 (1963) 7. A. AVDEEV, K.N. RAYMOND, K.O. IIODGSON and A. ZALKIN, Inorg. Chem., 1083, 11, 1972 8. K.W. BAGNALL, D. BROWN and D.G. ilOLAH, J. Chem. Soc. (A) 1149, 1968 9. L. HOCKX, J. GOFFART, G. DUYCKAERTS Spectrochim. Acta, in press°

~md P. TEYSSIE