A new uranium(IV) organometallic tetrahydroborate complex. The preparation and characterization of the bis(cyclopentadienyl)uranium (iv) bis(tetrahydroborate):(η5c5h5)2u(bh4)2

C21 Journal of OrgwzometaIIicchemistry. 142 (1977) C21-C24 0 Elsevier Sequoia S-A.. Ia-ne - Printed in The Netherlands Preliminary A NEW THE

URANIUM(IVI

AND

URANIUM

ZANELLA:

’

ORGANOMETALLIC

PREPARATION

DIENYLI

P.

communication

G.

TETRAHYDROBORATE

CHARACTERIZATION

OF THE

(IV) BIS (TETRAHYDROBORATE):

DE

PAOLI

and G.

COMPLEX.

BIS(CYCLOPENTA-

( &C5H,I,U(BH&

BOMBIERI

Laboratorio di Chimica e Tecnologia dei Radioelementi de1 C. N.R.. della Ricerca, Corso Stati Uniti, 35100 - Padova - Italy. G.

ZANOTTI

Istituto R.

Area

di Chimica

Organi_ca,

Universith

di Padova,

35100

- Padova

- Italy.

ROSS1

Istituto

Chimico,

(Received

Universita

October

19th.

di Ferrara,

44100

- Ferrara

- ItaIy.

1977;

SUMMARY The

synthesis

and room

and characterization

temperature

Hnmr

tic equivalence

of the bridge

X-ray

results

analysis

of (~-C5H512U(BHq)2

data support

a tridentate

and terminal

BHq

suggest

a structure

an approximately

tetrahedra1

pentadienyl

and two tetrahydroborate

The

rings

few examples

reported rivatives.

of organometallic

in the literature 1

The interest stions arising to the metal (III) ligand.

configuration

are

concerned

hydrogen

consisting

are

ligation

reported.

atoms.

Preliminary

of the uranium

surrounded

atom

since

the ligation St may

geometry

in

by. two pentahaptocyclo

groups.

tetrahydroborate with uranium(IVI

complexes

of actinides

and thorium(IVI

in this class of compounds is chiefly due to the structural from

1-r.

and the magne-

of the tetrahydroborate

act as a monodentate(

bidentate(I1)

anion

de-

quesBHi

or tridentate

In order

to investigate

ted to the metal red the complex UC14

f

2NaBH4

UC12(BH4)2

+

On account

how the number

DM2zIzTHF_

UC12(BH4)2

2(,5-C,H,)Tl

were

carried

than 5 ppm)

ne=DME

and tetrahydrofuran=THF).

using

very

was added

to asolution

of 1 g (2.6

stirring

IO hours

for

and to the resulting The

reaction

tered

off.

vent.

This

slow

green

Calcd.

The same dition

of

product

C,

was

mmoles)

12 hours

of the reaction

amount UC1

4

by

con-

(dimethoxyethaNaBH4

ml of tetrahydrofu-

removed 5 of (q-C

by filtration

H ITI was ad5 5 and the TIC1 fil-

at 20°C

by vacuum

evaporation of the sol-2 (10 at 80°C mmHg). By

30.18;

was prepared

the theoretical

filtered

H,

4.52.

Found:

an alternative

of NaBH4

were

C,

route.

to a DME

+- 2f15-CgH5)Tl

crystals

29.93; This

solution

(the resulting

obtained. H,

4.62.

involved

containing TIC1 being

adthe

pre-

off].

infrared spectrum of the title compound, recorded over the range 4000-1 (Nujol mulls were prepared in box with dry, degassed Nujol) shows

cm

a strong ting)

for

was obtained

for C 10H18B2U:

viously The

g (5.2

2~1~1

and moisture,

of purified

in 50

by vacuum sublimation -2 (IO at 60°C mmHg) red brown

product

600

solvents

of UC14

+

dry box (oxygen

mmoles)

the NaCl

was purified

resublimation

Anal.

I.4

was stirred

solid

g (5.2

mmoles)

at 20°C

solution

mixture

A red brown

to oxygen

atmosphere

0.169

coordinawe prepa-

(:-c~H~)~u~BH~)~

dry and oxygen-free

ran.

ded.

ligands

2NaCl

of the tetrahydroborate

out in a nitrogen

tent less

After

of other

f

2o”c _ or THF

DME

of the sensitivity

the reactions

and nature

may influence the mode of the BH, group ligation, 5 (q-C H 1 U(BH 1 by the following route: 5 52 42

singlet

(2480

and a strong

observed

bands

tate ligation

cm -%

band (1180

may

, a doublet (2140 -1, cm J. According

be considered

by the BH4 grap.

to provide

Furthermore,

bonded

cyclopentadienyl groups are present -1 : In-plane wagging), ging and 1010 cm In the room

temperature

hexadeuterobenzene, ppm@H)

are

present

60

a singlet (intensity

MHz (10 ratio

pmr

and 2200

cm -l;

to T. J.

Marks

significant

60

cm-l split2 et al. the

evidence

for triden-

the modes characteristic of n; -1 (800 cm : C-H out-of-plane wag-

spectrum

H) at +1.93

of (&C5H5)2U(BI-i412

ppm and a quartet

af the bands

: 10/S

).

The

.

in

at t26.57

data are

rela-

C23

tive

to internal

netic

benzene

equivalence

(+ indicating

Crystal

data. space

fl= 92,75(g)“, radiation

ter

C 10H18B2U. group

scan has

unit.

tetrahedral

two

The

bon atom

positions

me disorder, Because

of the carbon

atoms

differ

molecules

aIlow

case

involving

the uranium

are 2.61

and 2.58

2.8

i.

Whereas

The

i

two angles

atom

the boron

disorder

or to a ti-

description

as being

units

viz.:

0.08

for the angIes).

The

in both cases

atoms

by do not

i

and 2.63

for

two U-B d;

for the

between

and the uranium

of

positions

formed

two independent

I, and 2.63

of the

in the crystal.

an outline

e.s.d.*s

vary

is

on the car-

and the approximate

The

distances

atom

and the centres

the structure

and 12”

in the

uranium

process

only

atoms

of the present

in-wiving

inde-

diffractome-

disordering

to a space

here

for molecule

the U-C

MoK,

molecules

positions

to a fluxional

us to describe

distances

A and

on the 1250

each

is some

either

of the boron

distances

2,

atom

we can give

(on the basis

mono-

c= 14.221(6)

on a automatic

around

There

of ($-C5H5)2-U(BH4)2.

significantly

molecule

geometry

be ascribed

positions

crystals,

12 % calculated

ma%

as in the ca-

Monocromated

(2-C5H5)2U(BH4)2

as apexes.

i.e. in the latter

Z=8.

(I)) collected

with the boron

rings

of the disordering The

b= 7’. 1488(3),

indicate

up to *=25’.

coordination

that may

the structure.

discrete

1 I> 2.5~

they

atoms

red prismatic

11 g.cmS3,

independent

in both cases

cyclopentadieny1

dark

R value

tecniques

and

BH4 hydrogen

24.636(g), dc=2.

Present

reflexions

a/26

structure

a3,

&,.

observed

asymmetric

two

a=

U= 2501.4

with the

The

M= 397.6,

P21,a,

0_=0,7107

pendent

to high field)

and terminal 3 complex.

se of the !(?-C5H5)3UfBH4)

clinic,

shifts

of the bridge

2.4

are

and

99.6

and 102.5”, It appears

that a Shtisfactqry

the individual work;

results

i.r. ported ted

uranium

the possibility favour

by the values

for

complexes

se of the U(BH414 tridentate,

ly.

atoms

ligation

of the U-B

distances

the distances

Confirmation

this

a tridentate

where

of the coordination

can only be achieved

of performing

in which 4

identification

a bidentate

the BH

4

are 2.520)

i

is

neutron

being

by the BH4 group. which

Iigation

unit is either

of these hypothesis

through

investigation

are

than

2.82(l)

is sup-

those

repor-

in the ca-

(bridging)

i

The

view

in fact,

as bidentate

of

diffraction

explored.

This

shorter

is present.

, and 2,90(l),

geometry

or

respective-

awaits the neutron diffraction

studies.

Acknowledgements. The authors fiir Radiochemie der Technischen and to G. Agostini for technical

are grateful Universigt assistance.

to Prof.

Dr.

M&chen

, for

F. Lux, helpful

Institut comments

REFERENCES 1

T, .I, Marks therein.

and J.R.

Kolb,

Chem.

2

T. J. Marks, W. J. ll, (197212540.

3

T.J.

Marks

4

E.R. S. J,

Bernstein, W.C. Hamilton, Lippard and J. J. Mayerle,

Kennelly,

and J.R.

Kolb,

J.R. J.

Rev., Kolb

Amer. T-A. Inorg.

77 (19771 263 and L.A.

Chem.

Sot.,

and references

Shimp,

Inorg.

Chem.,

97 (197.51 27.

Keiderling, S.J. Chem., l~t19721

La Placa, 3009.