Synthesis and characterization of ammines of group VB trihalides

INORG. NUCL. CHEM. LETTERS Vol. 14, pp. 275-277. © P e r g a m o n Press Ltd. 1978. Printed in Great Britain

OO20-1650/78/O901-O275502.OO/0

SYNTHESIS AND CHARACTERIZATION OF AMMINES OF GROUP VB TRIHALIDES

A. K. Biswas a, J.R. Hall 6 and D.P. Schweinsberg c a

Department of Mining and Metallurgical of Queensland,

b

Engineering,

University

Brisbane, Australia 4067

Department of Chemistry,

University of Queensland,

Brisbane,

Australia 4067 e

Department of Chemistry, Queensland Brisbane, Australia,

Institute of Technology,

4000

(Received 28 March 1978; received for publication 2 June 1978) Although a number of publications

have appeared describing

complexes of Group VB trihalides with nitrogen containing donors such as butylamine(1),

trimethylamine(2,3)

has been made to characterize

and aniline(4)

no attempt

the simple an~nine adducts of this type

reported as early as 1830 (5). While there may be some doubt as to the stoichiometry compounds

reported in this early work

of the

(5), we have isolated the

compounds MX3.NH 3 (where M = As,Sb and Bi; X = Br and I) and SbCI3.2NH 3 in an analytically

pure state.

They may be synthesised either by

reaction of NH 3 with a solution of the trihalide

in benzene or ether,

or by heating a solid mixture of the metal oxide with an ammonium halide.

The bromides are yellow,

is white. ammonolysis

AsCl 3

the iodides are red and SbCI3.2NH 3

and BiCl 3 appear to be particularly

susceptible

The complexes are, in general, stable in air, practically in common solvents, but hydrolysed by water. could be determined.

insoluble

No molecular weights

Mass spectra did not yield a parent molecular

ion but rather the fragmentation decompose without melting. dissociate.

to

and no ammine adducts of these two halides could be prepared.

pattern for MX 3.

All compounds

Some sublime in a melting-point

tube, others

SbBr3.NH 3 may be sublimed unchanged i n vacuo.

infrared spectra of the compounds were characteristically

broad.

Coordinated NH 3 was indicated by bands in the region of 3100 cm -I (9(N-H)) ,1400 cm -I (BNH 3) and 850-600cm -I (pNH3). frequency was attributed (see Table ]).

to bands appearing

The M-N stretching

in the region 600-475 cm -l

The MX3 moiety was represented by several broad bands

in the M-X stretching and MX 3 deformation

regions, generally slightly

lower in frequency than those for the trihalides 275

themselves

(6).

276

An~ines of Group VB Trihalides

TABLE I Some Infrared Frequencies for the Ammine Adducts of MX 3.

Compound

v(N-H)

~(NH3)

AsBr3.NH 3

3102

1397

p(NH3)

v(M-N) 595

3022 Asl3.NH 3

3040

1380

820

573

SbCI3.2NH 3

3140

1400

666

548

745

520

3000 SbBr3.NH 3

3110

1395

630 Sbl3.NH 3

3107

1391

747

3000

529

623

BIBr3.NH 3

3084

1396

--

502

Bil3.NH 3

31lO

1390

~

475

3000

Raman s p e c t r a o f the f i n e l y

d i v i d e d compounds showed, in g e n e r a l ,

intense f e a t u r e s due t o the MX3 v i b r a t i o n s and weak bands due t o N-H s t r e t c h i n g and NH3 d e f o r m a t i o n .

An NH3 rocking mode (682 cm-1) was

observed only in the case of AsBr3.NH 3.

No bands a s c r i b a b l e t o M-N

s t r e t c h i n g were d e t e c t e d . Various s t r u c t u r a l

models may be proposed f o r MX3.NH3.

t h a t the compounds are e s s e n t i a l l y

We b e l i e v e

monomeric in the s o l i d s t a t e since

the M-halogen s t r e t c h i n g frequencies are c o n s i s t e n t w i t h values f o r t e r m i n a l halogen r a t h e r than b r i d g i n g halogen.

In t h i s

respect we have

taken the Sb-C1 s t r e t c h i n g frequencies (320, 291, 269 cm"1) of SbCI3.NH2C6H 5 (known to be monomeric (49 as a guide.

The Sb-C1 s t r e t c h i n g

f r e q u e n c i e s of SbC13.2NH 3 are 343, 293 and 274 c m - l , comparable w i t h those f o r the a n i l i n e

compound.

We t e n t a t i v e l y

conclude t h a t SbBr3.NH 3

and Sbl3.NH 3 a l s o c o n t a i n t e r m i n a l halogen atoms since the r a t i o of M-X s t r e t c h i n g frequencies f o r c h l o r i d e , bromide and i o d i d e in these ammine compounds is 1 : 0.7 : 0.5 in reasonable agreement w i t h the accepted r a t i o s (7)Since we have been unable t o o b t a i n c r y s t a l s s u i t a b l e f o r X-ray diffraction

s t r u c t u r e a n a l y s i s , we t e n t a t i v e l y

suggest t h a t the

compounds MX3.NH3 have a s t r u c t u r e based on a t r i g o n a l bipyramid w i t h two halogens and a lone p a i r of e l e c t r o n s occupying e q u a t o r i a l s i t e s . The compound SbC13.2NH 3 may have an octahedrai c o n f i g u r a t i o n w i t h two c h l o r i n e s , n i t r o g e n and a lone p a i r o f e l e c t r o n s in the one plane ( F i g u r e 1).

Ammines of Group VB Trihalides

X~.! H3

NH3 Cl ~ , . I

~ :

CI ~ S l S ~ N H 3 Cl

:

X Fi ~]ure l

Proposed structures for ammine complexes MX3,NH 3 and SbCI3.2NH 3. We have also prepared and characterized by vibrational spectroscopy methylamine, dimethylamine, trimethylamine and aniline complexes of selected antimony and bismuth trihalides.

Acknowledgement One of the authors (D.P.S.) thanks the Queensland Institute of Technology for leave to pursue this work. References I.

T.N. SUMAROKOVAand R.A. KUIDINA, Izv. Akad. Nauk Kaz. SSR, Ser. Khim. 2__5, 16 (1975).

2.

M. WEBSTERand S. KEATS, J. Chem. Soc., (A), 836 (1971).

3.

D.H. BOAL and G.A. OZIN, J. Chem. Soc., Dalton, 1824 (1972).

4.

R. HULME, D. MULLEN and J.C. SCRUTON, Acta Crystallogr., Sect.A, 2_55, SI71 (1969).

5.

J.W. MELLOR, A Comprehensive Treatise on Inorganic and Theoretical

6.

S.D. ROSS, Inorganic Infrared and Raman Spectra, p.174. McGraw-Hill,

7.

A.M. BRODIE and C.J. WILKINS, Inorg. Chim. Acta, 8, 13 (1974).

Chemistry, Volume IX, p.664. Longmans, Green and Co., London (1933). London (1972).

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