Stable complexes of manganese (III) with oxides of pyridine, phosphine and arsine

INORG. NUCL. ~ CHEM.

LETTERS

Vol, 8, I ~ . 287-291, 1972.

Pergamon

Press.

Printed

in

Great

I~ritain.

STAELE COMPLEXES OF MANGANESE ( I I I ) WITH OXIDES OF PYRIDINE, PHOSPIIINE AND ARSINE E . £ o n t r e r a s , V . R i e r a and R.Us6n Oepartment o f I n o r g a n i c C h e m i s t r y University

of Zaragoza.

(Received 2 November I ~ 1 ;

in revised ~

A few complexes o f M n ( l l l )

Spain. 9 December 1971)

(1-7)

are known, whose

stability i n a i r and at room t e m p e r a t u r e i s g e n e r a l l y so l i m i t e d that their study is quite difficult and t h e r e f o r e our knowledge about t h e i r

stereochemistry,

magnetic behaviour,

properties,

etc. is still incomplete. The o x i d e s of p y r i d i n e ,

spectral

p h o s p h i n e s and a r s i n e s

h i g h d i p o l e moments and t h e i r oxygen atom, which i s in f a c t n e g a t i v e end of the d i p o l e is a good ~ and ~ d o n o r . T h e i r

have the oxygen

atom i s f u r t h e r m o r e not v e r y p o l a r i z a b l e and t h e r e f o r e the m e n t i o n e d l i g a n d s o f f e r the o p p o r t u n i t y to s t a b i l i z e high valencies of t r a n s i t i o n with

e l e m e n t s , f o r i n s t a n c e manganese ( I I I ) . In t h i s paper we d e s c r i b e manganese ( I I I )

o x i d e s of p y r i d i n e

triphenylarsine magnetic

(OPy),

(OAsPh3),

triphenylphosphine

together

~ith

their

complexes

(OPPh 3) and

spectral

and

properties. Experimental

Preparation

of the complexes Cold e t : ~ a n o l i c

solutions

of the t h r e e

ligands

(OPy,OPPh3,0AsPh3) were added to s o l u t i o n s of MnCI 3 i n e t h e r , f r e e from hydrogen c h l o r i d e , prepared a c c o r d i n g to (3) and kept at t e m p e r a t u r e s below -30°C. The r e a c t i o n s were c a r r i e d out under dry c o n d i t i o n s .

In e v e r y e x p e r i m e n t p r e c i p i t a t e s

287

vpere o b t a i n e d ,

288

STABLE COMPLEXES OP MANGANESE OH)

Vol. 8, No. 3

uhich were f i l t e r e d , washed in cold dry e t h e r ( t h e p r e c i p i t a t e o b t a i n e d ~vith OPy was washed in cold dry e t h i l i c a l c o h o l ) and d r i e d in vacuo. Analysis The o b t a i n e d s o l i d s v;ere i d e n t i f i e d as: t r i - c h l o r o t r i s ( p y r i d i n e oxide)-manganese ( I I I ) , [~n(OPY)3Cl3] ( I ) ; t r i chloro-tris ( t r i p h e n y l p h o s p h i n e o x i d e ) manganese ( I I I ) , IMn(OPPh3)3CI3~(II); t r i - c h l o r o - t r i s ( t r i p h e n y l a r s i n e oxide) manganese (III),Irln(OAsPh3)3Cl31 ( I l l ) , in accordance w i t i l tile r e s u l t s of t h e i r analyses which are given in Table I TABLE I %

Found

CII Mn N Oxid.

25.88 12.30 9.73

23.82 12.30 9.41

10.61 5.52 . . .

2.99

3.00

3.00

3.00

3.20

3.00

3.01

3.00

2.98

3.00

3.00

3.00

numb. Cl/Hn

Calc.for F o u n d Calc.for Found Calc.for [~In(OPY) 36131 [Mn (OPPh3)3C131 [Mn(OAsPh3)3CI ~

10.68 5.52 . . . .

.

~.~3 4.07 . . .

9.43 4.87 .

Properties The three complexes are stable in a i r at room temperature. Complex ( I ) blue and complex ( I I I )

is a reddish black, complex ( I I )

a deep

a paler blue s o l i d . Their melting points

are 139 ° , 243 ° and 169°C, r e s p e c t i v e l y , although complex ( I I ) undergoes a change of color at 142°C (from Blue to white), which is due to a decomposition

under reduction to manganese ( I I ) .

Complex ( I ) is only soluble in methyl alcohol (with instantaneous decomposition), in pyridine and in warm chloreform; complexes ( I I )

and ( I I I )

are soluble in a larger number of solvents;

methyl and ethyl alcohol, acetone,

chloroform, nitromethane and

pyridine. When the coloured solutions thBs oLtained are l e f t

in

a i r they eventually become colourless. The c o n d u c t i v i t i e s of fresh prepared solutions in acetone,

nitromethane and pyridine are tile follo~ing

(Table I I ) :

Vol. 8, No. 3

STABLE COMPLEXES OF MANGANESE 01D

TABLE I I . Molar

Complex

Conductance

concn.

(solvent)

(I)

5.11

289

data Temp.,

Molar

°C

conductivity

x 10 -4

20

33

29

5

(acetone)~ (I)

3.01

x 10 -4

(pyridine) (II)

2.40

x 10 -4

21.5

35

21

33

28

8

22

38

25

52

23

8

(acetone) (II)

2.42

x 10 -4

(nitromethane) (II)

1.15 x 10 -4 (pyridine)

(III)

5.04 x 10 -4 (acetone)

(III)

4.85 x 10 -4 (nitromethane)

(III)

2.13 x 10-4 (pyridine)

Infrared

spectra The i n f r a r e d

using

Ilujol

mulls

show t h e

t h e 300 cm - I region

of

vibration smaller

~ (X-O)

(beeing

wave numbers,

ligands

complexes.

the

the

sheets,

absorption

Besides,

the

undergo

were measured with

Other

of of

of

is the

They

t h e Mn-CI

bonds

t h e Mn-O bonds shifted

the

in

in the

stretching

towards

neu Bond Mn-O causes

characteristic

changes w i t h

a ~eckmann

cm - I .

band due to

X = N, P, As) formation

t h e X-O bond.

do n o t

III)

range 4000-250

and t h e a b s o r p t i o n s

400 cm - I

t h e v1eakening o f free

over

characteristic

region

over

(Table

between p o l y e t h y l e n e

IR 20-A s p e c t r o p h o t o m e t e r al~lays

spectra

bands o f

the formation

of

the

the

STABLE COMPLEXES OF MANGANESE (lID

290

T~GLE I I I .

Partial

Complex

infrared

spectra

data

Vol. 8, No. 3

(in..cm -1)

~ (Mn-~l)

~(Mn-O)

~(Z-O) complex

310;270

420

1185;1215

1228

Mn(OPPh3)3CI 3

340

410

1145;11C0

1190

~n(OAsPh3)3Cl 3

330;280

455

830

Mn(OPY)3CI 3

(X=N,P,As) free ligand

880

Magnetic data The magnetic s u s c e p t i b i l i t i e s of the three complexes were measured w i t h the Faraday method at f i v e d i f f e r e n t temperatures between 70 and 300°K. The observed b e h a v i o u r i s in accordance vJith the expected one f o r t h a t of high spin manganese (III) complexes. The magnetic s u s c e p t i l ~ i l i t i e s follow a CurieWeiss law w i t h n e g a t i v e paramagnetic c o n s t a n s , s m a l l e r than 6°K The moments c a l c u l a t e d from our e x p e r i m e n t a l data range between 5.2 and 5.4 B.M. Ultraviolet

and v i s i b l e

with pyridine absorption

spectra

These were taken from a Beckmann DU s p e c t r o p h o t o m e t e r and c h l o r o f o r m s o l u t i o n s of the complexes.

The c h l o r o f o r m bands:

solutions

~kmax(cm " I )

show the f o l l o w i n g Emax(l.mole - I

Complex ( I )

15,870 II,490

380 185

Complex ( I I )

17,240

560

Complex ( I I I )

14,710

510

cm - I )

The band observed in complexes ( I I ) and ( I I I ) is strongly asimmetric, since i t penetrates deeply in the region of lower energies. These features together with the existence of the lo~c eneroy band (11p490 cm-1) in complex (1) must be

Vol. 8, No. 3

STABLE COMPLEXES OF MANOANESE (Ill)

291

interpreted (8) as a consequence of the s p l i t t i n g of the Eg ground state due to the d i s t o r t i o n of the octahedral

f i e l d surrounding

the manganese ( I l l ) . The pyridine solutions show a single band at 23,810 cm-1 solutions.

J

in accordance with the red colour of the three The exact likeness of the three spectra proves that

the species in solution is in every case the same, probably as a r e s u l t of the substitution of solvent molecules for the three ligands. Acknowledgement We thank Prof.Dr. F.G6mez Beltr~n for his advice and help during the magnetic measures. References 1.- F.A.COTTON, G.WILKINSON

Advanced Inorganic

Chemistry. p.837

Second. Ed., Wiley, New York (1966) 2.- H.A.GOODWI~, R.N.SYLVA

Aust.J.Chem. 18 1743 (1965);

ibid.

20 629 (1967) 3.- If. FUNK, II.KREIS - Z.Anorg. Chem. 349 45 (1967) 4.- R.E.HAMM, M.A.SWIN - Inorg.Chem. 6 139 (1967) 5.- C.P.PRABHAKARAN, C.C.PATEL

J.Inorg.~lucl.Chem.

30 867 (1968)

C.- P.R.EATON, W.R.McCLELLAN, J.F.WEIHER - Inorg.Chem. 7 2040

(1968) 7.- t~.F1. REIFF, W.A. BAKER Jr.

Inorg.Chem. 9 570 (1970) m

8.- T.S. DAVIS, J.P.FACKLER, M.J.WEEKS -Inorg. Chem. 7 1994 (1968)