Transition Metal Chemistry Volume 20 Issue 5 1995 [Doi 10.1007%2Fbf00141508] Parimal Kundu; Samiran...

8/10/2019 Transition Metal Chemistry Volume 20 Issue 5 1995 [Doi 10.1007%2Fbf00141508] Parimal Kundu; Samiran Mitra; Sonjay Kumar; Dilip Banerjee; Rang -- Solid

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Transition Met. Chem., 20 , 417 422 (1995) D oub le com plex sa l ts o f cyc l ic d iamine l igands 417

So l i d s t a t e M 6 s s ba ue r , e .p . r . , m a g ne t i c pr o pe r t i e s a nd t he r m a l l y

i n d u c e d s t e r e o c h e m i c a l s tu d i e s o n d o u b l e c o m p l e x s a lt s o f c y c li c

d i a m i n e c o n t a i n i n g c a t i o n i c c o p p e r I I) c o m p l e x e s a n d a h e x a -

cyanoferrate I I I ) an ion

Par imal Kundu and Samiran Mi tra

Depa rtment o f Chemistry , Jadavpur University , Calcutta 700 032, India

Sonjay Kum ar , Di l ip B aner jee and Ranga Lal B hat taeharya

Dep artm ent of Physics, Calcutta University, 92 Ach arya PrafulIa Chandra Road , Calcutta 700 009 , Ind ia

S u m m a r y

Do u b l e c o m p l e x s a lt s c o n t a i n i n g c a t i on i c C u n h a v i n g

cycl ic l igand p iperaz ine (pipz) , N-methy lp iperaz ine

(mpipz) and N,N' -d imethy lp iperaz ine (dmpipz) and hexa-

cyanoferra te ( I I I ) ion have been syn thes ized and charac-

te r ized by e lem en ta l an a lyses , i. r . and e lec t ron ic spec t ra ,

a n d m a g n e t i c m o m e n t m e a s u re m e n t s . M 6 s s b a u e r s p e c t r a

a t r o o m t e m p e ra t u re a n d a t 8 0 K , we re r e c o rd e d in o rd e r

t o e v a l u a t e t h e m e t a l -m e t a l c h a rg e t r a n s f e r a n d t h e

impa ct o f the cyc l ic l igand p resen t in ca t ion ic moie ty o f

t h e d o u b l e c o m p l e x s a l t u p o n t h e M 6 s s b a u e r s p e c t r a o f

t h e h e x a c y a n o fe r r a t e ( II I ) i o n. E v i d e n c e fo r m e t a l -m e t a l

charge t rans fer i s suppor ted by e lec t ron ic spec t ra and

magnet ic suscep t ib i l i t i es . Var iab le t empera tu re e .p . r .

s p e c t r a we re r e c o rd e d i n o rd e r t o d e t e rm i n e t h e d i s t o r t io n

of c rys ta l sys tem. Therma l ly induced s te reochem ica l s tu -

d ies have been ca rr ied o u t w i th the he lp o f i . r . spec t ra l

d a t a . K i n e t i c s o f th e rm o c h e m i c a l r e a c t i o n s h a v e a l s o b e e n

s tud ied . Act iva t ion energ ies (E*) and incep t ion tempera-

t u r e s fo r t h e t h e rm o c h e m i c a l r e a c t i o n s s h o w t h e o rd e r o f

s tab i l i ty o f the doub le complex sa l t s fo l lows the t rend :

dmp ipz > mpipz > p ipz , wh ich ind ica tes tha t the + I e f -

fec t i s mo re p ron oun ced than s te r ic ef fec t.

Introduction

S t u d i e s o f d o u b l e c o m p l e x s a l t s a n d c y a n i d e -b r i d g e d

complexes con ta in ing ca t ion ic meta l ( I I / I I I ) complexes

and hex acyano ferra te ( I I I / I I ) ions a re o f par t i cu la r in te res t

i n c o n n e c t i o n w i t h e l e c t ro n t r a n s f e r p h e n o m e n a i n t h e

so l id s ta te . Unfo r tuna te ly , wel l charac te r ized complexes

have no t been repor ted , excep t ing those con ta in ing

ca t ion ic ru then ium(II I ) (1) and manga nese(I I ) (2) comp lexes

a s a c o u n t e r i o n . F u r t h e r s t u di e s a r e n e e d e d fo r a d v a n c e d

eluc ida t ion o f e lec t ron t rans fer reac t ion s o f meta l c om -

p lexes in the so l id s ta te . Suzuk i and Uehara

et al. ~3)

h a v e

s t u d i e d th e rm a l a n d e l e c t ro n i c p ro p e rt i e s o f d o u b l e c o m -

p lex sa l t s and cyan ide-b r idged complexes con ta in ing

ca t ion ic copper( I I ) complexes wi th an acyc l ic d iamine

l igand and a hexacy anoferra te ( I I ) ion. These au thors c i t ed

charge t rans fers f rom i ron (II ) to copper( I I ) , the s tab i l i ty o f

the [C u(L2)] 2+ moie ty decre as ing due to the in f luence o f

the Fe(CN)64- ion . The a im o f the p resen t w ork w as to

p re p a re d o u b l e c o m p l e x s a l ts a n d c y a n i d e -b r i d g e d c o m -

p lexes con ta in ing ca t ion ic copper( I I ) hav ing a cyc l ic

l igand and a hexacyanoferra te ( I I I ) ion , in o rder to observ e

* Author to who m all correspondenceshou ld be directed.

the charge t rans fer ph enom ena and the e f fec t o f the

Fe(CN)63- ion on the s tab i l i ty o f copper( I I ) complexes

conta ining cycl ic l igands.

S t ru c t u ra l a n d M 6 s s b a u e r s p e c tr a l s tu d i es o n P ru s s i a n

b l u e - t y p e c o m p l ex e s h a v e b e e n r e p o r t e d ~-8 ) b u t n o M 6 s -

s b a u e r s t u d y h a s b e e n m a d e o n t h e d o u b l e c o m p l e x s a l t

con ta in ing the copper( I I ) ca t ion cyc l ic l igand and hexa-

cyanoferra te ( I I I ) . Thus , a fu r ther pu rpose o f the p resen t

wo r k wa s t o s t u d y M 6 s s b a u e r s p e c t r a a n d t o i n te rp re t t h e

d i f fe rence in spec t ra l param eters f rom the C u 3 Fe(CN )6 ] 2

due to the p resence o f the cyc l ic l igand in the ca t ion ic

copper( I I ) un i t . At tempts have a l so been made to d raw

conclus ions as to the d i s to r t ion o f the c rys ta l due to

inser t ion o f the cyc l ic l igand in the c a t ion ic mo ie ty o f

the complexes , f rom the tem pera tu re-dep enden t e .p .r .

spectra(9-1 ~.

A l t h o u g h t h e rm a l l y -i n d u c e d s t e r e o c h em i c a l c h a n g e s o f

cyc l ic l igand co mplexes in the so l id s ta te have been re -

por ted (~2 '13), th is is not the case for the dou ble com plex

sa lt s. O ne p urpos e o f the p resen t w ork i s to s tudy

s te reochem ica l changes du r ing thermal de com pos i t ion .

K i n e t ic s a n d t h e rm o d y n a m i c p a ra m e t e r s fo r t h e d e h y d ra -

t ion and decompos i t ion in the so l id s ta te have been

ca lcu la ted . The s tab i l i ty o rder o f the com plexes wi th

respec t to me thy l subs t i tu t ion in the cyc l ic l igand are a l so

discussed.

Experimental

Materials and methods

Metal sal ts (A.R. grade) were used as received. Pipz (S.D.

f ine chemica l s , Calcu t ta ) , mp ipz (Spec t rochem, Bombay)

and dmpipz (Ald r ich Co . , USA) were used as supp l ied .

Preparation of the complexes

The l igand (pipz , mpipz o r dm pipz) was adde d in excess,

wi th con s tan t s t ir r ing , to an a que ous so lu t ion (30c m 3)

con ta in ing CuC1 z (ca 3 re too l) un t i l the so lu t ion becam e

clear. An aque ous so lu t ion o f K3 [Fe(C N)6 ] (30cm 3 ,

2 re too l ) was then added wi th cons tan t s t i r r ing and the

s o l u t io n b e c a m e p u rp le . T h e c o m p l e x wa s p re c i p i ta t e d b y

a d d i n g M % C O a n d wa s c o ll e c te d b y fi lt r at io n , wa s h e d

c a re fu l ly w i t h c o l d H2 0 a n d d ry E t 2 0 a n d d r i e d o v e r

fused C aC1 2 in a d esiccato r. (Yield ca 6 0 % ) . T h e c o m -

p l e x e s h a v e t h e c o m p o s i t i o n [ -C u L 2 ] [L 2 C u C NF e -

(C N)5 12 " n Hz O , wh e re L = p i p z , m p i p z o r d m p i p z a n d

n = 5 o r 6 .

0340 4285 9 1995 Chapman Hall


2/6

4 1 8 K u n d u et al.

Table 1 . Analyt ica l da ta for the doub le complex sa lts

T r a n s i t i o n M e t . C h e m . , 2 0 , 4 1 7 - 4 2 2 ( 1 9 95 )

Co mp oun d a Colo ur Fo un d (Calcd .)(%) Pefr

C N H Cu Fe (B.M.)

I ) m aro on 35.3 27.0 5.4 15.5 9.1 3.74

(35.4) (27.5) (5.7) (15.6) (9.1)

2 ) pu rp le 38.3 25.3 6.2 14.3 8.3 3.69

(38.1) (25.4) (6.3) (14.4) (8.4)

3 ) pu rp le 41.1 23.7 6.6 13.5 7.9 3.55

(41.0) (23.9) (6.8) (13.5) (719)

(1) [ C u L ] ] [ L 1 , C u C N F e ( C N ) 5 ] 2 . 5 H 2 0 ; (2) [ C u L ~ ] [ L ~ C u C N F e ( C N ) s ] 2 . 6 H 2 0 ; (3) [ C u L , 3 ] [ L ~ C u C N F e ( C N ) 5 ] 2 . 6 H z O ; L = p i p e r a z i n e ,

L 2 = N - m e t h y l p i p e r a z i n e a n d L 3 = N , N - d i m e t h y l p i p e r a z i n e .

C , H , N w e r e e s t i m a t e d u s i n g a P e r k i n - E l m e r 2 4 0 C

e l e m e n t a l a n a l y s e r ; e l e m e n t a l a n a l y s e s a r e g i v e n i n

T a b l e 1 . T h e r m a l i n v e s t i g a t i o n s ( t . g ,a . a n d d . t. a .) w e r e

c a r r i e d o u t o n a S h i m a d z u D T - 5 0 t h e r m a l a n a l y s e r u n d e r

a N 2

a t m o s p h e r e w i t h a h e a t i n g r a t e o f 1 0 ~ m i n - 1 a n d

c ~- al um i na a s a s t a n d a r d . I . r. s p e c t r a w e r e r e c o r d e d u s i n g

a P e r k i n - E l m e r 5 9 5 S p e c t r o m e t e r w i t h K B r d is cs . T h e

e f fe c ti v e m a g n e t i c m o m e n t s w e r e e v a l u a t e d f r o m m a g n e t -

i c s u s c e p ti b i li t y m e a s u r e m e n t s w i t h a n E G & G P A R 1 55

v i b r at i n g s a m p le m a g n e t o m e t e r a t r o o m t e m p e r a tu r e .

V a r i a b l e t e m p e r a t u r e m a g n e t i c m e a s u r e m e n t s w e r e c a r -

r ie d o u t w i t h a F a r a d a y t y p e m a g n e t o m e t e r ( M a n i c s

D S M B ) e q u i p p e d w i t h a n O x f o r d H e c o n t i n u o u s - fl o w

c r y o s t a t w o r k i n g i n th e 4 . 2 - 3 0 0 K r a n g e , a n d a D r u s c h

E A F 1 6 U E e l e c t r o m a g n e t . S o l id s t a te e l e c tr o n i c sp e c t r a

w e r e r e c o r d e d u s i n g H i t a c h i U - 3 4 0 0 ( u . v . - v i s . - n e a r- i .r . )

m o d e l e l e c t r o n i c s p e c t r o p h o t o m e t e r . E . p . r . s p e c t r a w e r e

r e c o r d e d a t 4 , 7 7 a n d 2 9 8 K w i t h a B r u k e r - 1 9 0 s p e c -

t r o m e t e r e q u i p p e d w i t h a c o n t i n u o u s f l o w c r y o s ta t , s 7 F e -

M 6 s s b a u e r s p e c t r a w e r e o b t a in e d u s i n g a C M T E c o n s t an t ,

a c c e l e r a t i o n d r i v e ( M o d e l 2 5 0 ) w i t h c a 5 mc i 57C o in Pd a s

s o u r c e . T h e t r a n s m i s s i o n s p e c t r a w e r e o b t a i n e d u s i n g

E C I L k r y p t o n - m e t h a n e f i l l e d p r o p o r t i o n a l c o u n t e r a n d

a s s o c i a t e d c o m p o n e n t s t o l i m i t d e t e c t i o n t o o n l y

1 4. 37 K e V y - r a y . T h e t r a n s m i t t e d r a d i a t i o n w a s r e g i s t e r e d

i n a 4 K P C A c a r d i n m u l t i s c a l a r ( M C S ) m o d e . T h e s p e c t r a

w e r e r e c o r d e d a t 3 0 0 a n d 8 0 K .

~ 1 7 0 " C

~ " ~ , - - - . . .~ ( 3 ) 1 2 5 " o c ^ /

' 1 40 ~C \ T O ~ - - ~ 1 8 5 ' 0 C 7

1 1 5 ~ ~ \ ~

. ~ T G " ' 4 - 4 - , 1 7 5 a 0 /

LG \ ~

\

'h i D T A

\ / / "

, , - ~ o - - c . . . ~ , . - . . . . . . . j . ~ . ' (3 1

t 11 ~ I / . ' D T A

/ , , /

I T

I ( 2 ) 2 . 5 m g j_ _

2 0 ~ V

J_

igure 1 . The rma l c u rve s o f c om pound 1 ) ), sample

mass 18.10mg; 2) ) , sample mass 14.00mg; and 3 )

( . . . ) , sample mass 9 .22 mg.

Results and discussion

A n a l y ti c a l da t a , c o l o u r a n d m a g n e t i c m o m e n t s f o r t h e

t h r e e n e w d o u b l e c o m p l e x s a lt s,

I ) - 3 ) ,

a r e g i v e n i n t h e

T a b l e 1. T h e p r e s e n c e o f l a tt i c e w a t e r m o l e c u l e s i n t h e

d o u b l e c o m p l e x s a l ts w a s c o n f i r m e d b y t h e p r e s e n c e o f i .r .

b a n d s a t ca 3 6 0 0 c m - 1, y ( O H ) , a n d a t 1 6 5 0 c m - 1, 6 ( H O H ) .

I .r . b a n d s a r e l i s te d i n T a b l e 2 A . O n h e a t i n g , t h e c o m -

pounds lo s t w a te r . Ma s s lo s s i n t .g .a , c u rve s c on f i rme d the

p r e s e n c e o f f i v e m o l e c u l e s o f w a t e r i n

1 )

a n d s ix m o l e c u l e s

o f w a t e r i n 2 ) a n d 3 ) (F igu re 1 , Ta b le 3 ) .

I n t h e c o m p l e x e s t h e c y c l i c l i g a n d s f u n c t i o n a s a c h e l a t e

i n t h e b o a t c o n f o r m a t i o n , a s s h o w n b y t h e a p p e a r a n c e

o f a d d i t i o n a l i .r . b a n d s b e t w e e n 7 0 0 a n d 1 4 0 0 c m - 1

( T a b l e 2 A ) c o m p a r e d w i t h t h e f r e e li g a n d w h i c h e x i s ts i n

t h e c h a i r f o r m ~12-17). F ro m the i . r . spe c tra l ba nd s i t is

i n f e r r e d t h a t b o t h t e r m i n a l a n d b r i d g i n g c y a n i d e s a re

p r e s e n t i n t h e c o m p l e x e s 1 8'1 9) . T h e ? ( C N ) a n d 6 ( C N )

va lue s a re g ive n in Ta b le 2A . I . r . s pe c t ra l ba nds fo r y (C N )

a p p e a r e d a t l o w e r f r e q u e n c e s t h a n i n K 3 [ F e ( C N ) 6 ] , i n -

d i c a t i n g t h a t t h e c h a r g e o n i r o n ( I I I ) r e d u c e d t o s o m e e x t e n t

i n c o m p l e x e s I ) - 3 ) ; i . e . c h a r g e t ra n s f e r p h e n o m e n a a r e

p r e s e n t i n t h e c o m p l e x e s . T h i s f a c t i s s u p p o r t e d b y e l e c -

t r o n i c a n d M 6 s s b a u e r s p e c t r a a n d m a g n e t i c m o m e n t s .

T h e e l e c t r o n i c s p e c tr a o f a ll t h e d o u b l e c o m p l e x s a l ts

w e r e r e c o r d e d i n t h e s ol i d st a t e a n d a r e s h o w n i n F i g u r e 2 .

A n e x t r a b a n d ( s h o u l d e r ) a p p e a r e d a t 1 06 5 n m i n a ll t h e

c o m p l e x e s w h i c h w a s n o t o b s e r v e d i n t h e i n d i v i d u a l d o u b l e

c o m p l e x s a l t s . T h i s e x t r a b a n d a p p e a r e d t o b e d u e t o

m e t a l - m e t a l c h a r g e t r an s f e r~3).

M 6 s s b a u e r s p e c tr a o f t h e c o m p o u n d s w e r e r e c o r d e d

a n d a r e s h o w n i n F i g u r e 3 . T h e i s o m e r s h i f t ( 6, IS ) a n d

q u a d r u p o l e s p l i tt i n g ( A , Q S ) v a l u e s ( T a b l e 4 ) w e r e d e t e r -

m i n e d b y a c o m p u t e r c u r v e - f i t p r o g r a m ~ 2~ a n d a r e e x -

p r e s s e d in m m s - 1. F o r c o m p l e x e s 1 ) - 3 ) t h e 6 ( m m s - a)

v a l u e s a r e c l o se t o z e r o a n d q u a d r u p o l e s p l i t ti n g s ( A) a r e

z e r o . S o i n st e a d o f o b t a i n i n g t h e c h a r a c t e r i s t i c q u a d r u p o l e

s p l i t t i n g s a n d i s o m e r s h i f t s f o r h e x a c y a n o f e r r a t e ( I I I )

t h e s p e c t r a i n d i c a t e d t h e p r e s e n c e o f h e x a c y a n o f e r r a t e ( I I )

b u t n o d e t e c ta b l e h e x a c y a n o f e r ra t e ( II I ) a t r o o m t e m p e r a -

t u r e . T h e l i n e w i d th s a t h a l f - h e i g h t ( F /2 ) o f a ll t h r e e c o m -

p l e x e s a r e a p p r e c i a b l y l a r g e . T h e M 6 s s b a u e r s p e c t r a f o r

c o m p l e x 1 ) a t 8 0 K c o n t a i n s o n e q u a d r u p o l e d o u b l e t


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4/6

4 2 0 K u n d u e t a l . T rans i t i on M e t . C hem . , 20, 417-422 (1995)

Table 3. T herm al parameters for the deh ydra tion and deligation of doub le complex salts

C o m p o u n d s

Deh ydrat ion process Del igat ion process

Temp. d.t .a, peak Ord er of E* Temp. d.t .a, peak Ord er of E*

range (~ temp. (~ reaction (k~Jm ol- 1) range (~ temp. (~ reaction (kJ m ol- 1)

(Endo.) (Endo:)

( I ) 35-75 45 2.0 173 170-250 19 0,2 20 , 1.5 170

240

( 2 ) 40-115 80 1.8 165 17 5- 25 5 18 0,2 20 1.5 176

( 3 ) 35-125 82 1.8 164 185-280 19 0, 26 0 1.5 181

1 o

3 0 5

0 ~ l t I I _ ~ I

2 0 0 6 0 0 1 0 0 0 1 4 0 0

W a v e l e n g t h ( n m )

F i g u r e 2 . E l ec t r o n ic s p e c tr a i n N u j o l m u l l o f c o m p o u n d 1 )

( ), ( 2 ) ( - - - )

and

( 3 ) ( . . . . ).

16.00

15.75

15.50

x 1 5 . 2 5

co

E 15.00

g

9 14.75

14.50

14.25 --- I

2 0 0 2 5 0 3 0 0

C h a n n e l n u m b e r

. . . 1

1 9 7 /

" ~ - [ 9 ( 2 ) . " . .

(3 11.7~- V

1 1 . 5 1 ~ 1 t

2 0 0 2 5 0 3 0 0


16.9

~ 1 6 . 6

x

us

9

9 16.3

16.0

190

(3)

9 e ' ,,

i i

2 3 0 2 7 0


F i g u r e 3 . M r s s b a u e r s p e c t r a o f c o m p o u n d s I ) a n d 2). T h e z e r o

1 1

v e l o c it y c h a n n e l is 2 4 7. 75 a n d t h e v e l o c i ty i s 0 . 04 m m s - c h a n n e l - .

C o m p o u n d 3 ) h a s a s i m i l a r s p ec t r u m .

Table 4. M 6ssbauer parameters for double complex salts

Com pound I somer Quadrupo l e 1 /2

shift a 'b splitting (mm s- ~)

(mm s -1) (mm s -1)

( I ) +0.0076 0 0.38

( 2 ) + 0.0232 0 0.40

( 3 ) +0.0121 0 0.39

Cu 3 Fe(CN)6 ~ - 0 .1800 0 .400

K4[Fe(CN)6] c + 0.0400 0

K3 [Fe(CN)6] c -0 .124 0 0 .28 0 -

aRelative to or-iron;bvelocity scale is calibrated by S~Co Pd source and

ct-Fe an d ct-Fe203 a bsor bers ; CRef. 8.

( IS = 0 .042 m m s - 1 ; QS = 0 .286 m m s - t ) and one s i ng le t

( IS = 0 .002 mm s - 1 ; 1 /2 = 0 .19 m m s - 1). Th e sm al l q uad -

rupo l e sp l i t t i ng o f t he doub l e t i nd i ca t es t he p resence o f

h e x a c y a n o f e r r a t e ( II I ) a n d t h e s i n g l e t c o r r e s p o n d s t o h e x a -

cyanofer ra t e ( I I ) . So , in t h i s co m po un d a cer t a i n perce n t age

o f hexa cyano fer ra t e ( I I I ) i s p resen t w h ich i s no t observed a t

r o o m t e m p e r a t u r e . F r o m t h i s r e s u l t i t i s c o n c l u d e d t h a t

c h a r g e t r a n s f e r o c c u rs i n th i s c o m p o u n d . T h e v a l u e o f F / 2

d e c r e a s e s w i t h t h e f a l l o f t e m p e r a t u r e f o r h e x a c y a n o f e r -

r a t e ( II ) wh ich i nd i ca t es t he l ow er ing o f d i s t o r t i on o f t he

sys t em w i th r edu ct i on o f t emp era tu re (21). W i th l ow er ing o f

t e m p e r a t u r e t h e a b s o r p t i o n p e r c e n t a g e i n c r e a s e s w h i c h

i n f o r m e d t h e p r e s e n ce o f p o l y m e r i c l a tt ic e . T h e M 6 s s b a u e r

s p e c t ra l p a r a m e t e r s o f c o m p l e x e s ( 1 ) - ( 3 ) are d i f f e ren t

f r o m C u 3 r F e ( C N ) 6 ] 2 ( 7'8). C u 3 [ F e ( C N ) 6 ] 2 exhibi t s a def i -

n i t e qua d rup o l e sp l i t ti ng (A) an d i somer sh i f t (Tab l e 4 ).

Th i s d i f f e rence a r i ses f rom the cyc l i c l i gand a t t ache d wi th

t h e c o p p e r (I I ) io n . T h e m a g n e t i c m o m e n t s o f c o m p l e x e s

( 1 ) - ( 3 ) a t r o o m t e m p e r a t u r e a r e m u c h l o w e r t h a n t h e

e x p e c t e d v al u es . V a r i a b le t e m p e r a t u r e m a g n e t i c m o m e n t s

o f c o m p l e x

( I )

(g iven i n Tab l e 5 ) a r e a lm os t c ons t an t .

Thus , n o an t i f e r rom agne t i c coup l i ng i s p resen t i n t h i s

c o m p o u n d . S i m i l a r p h e n o m e n a a r e a l s o o b se r v e d in c o m -

plexes

( 2 )

a n d

( 3 ) .

From the above d i scuss ions i t i s

c o n c l u d e d t h a t c h a r g e t r a n s f e r o c c ur s i n a ll th e c o m p o u n d s

in t he d i r ec t i on : L

~ Cu II ~

Fe m, wh ich i s fu r t her su ppor t ed

by t he h igher t herm al s t ab i l i t y o f ca t i on i c copper ( I I ) cyc l ic

l i g a n d c o m p l e x e s i n d o u b l e c o m p l e x s a l t s c o m p a r e d t o

[ C u L 2 ] X 2 c o m p l e x e s ( 22 '2 3) .

I n c o m p l e x ( 1 ) var i ab l e t empera tu re e .p . r , spec t r a have

been r e co rded i n t he so l i d s t a t e (F igu re 4 , Tab l e 6 ) and an

u n u s u a l p h e n o m e n o n i s o b s e r v e d . W i t h t h e l o w e r i n g o f

t em pera tu re , t he d i f f e rence i n e .p .r , spec t r a l band s due t o

C u 2 + c e n t re s g r a d u a l l y de c r e a s e s a n d a t 4 K m e r g e s t o g i v e

o n e b r o a d p e a k . F r o m t h e l i t e r a t u r e i t i s k n o w n t h a t

P r u s s i a n b l u e a n a l o g u e s h a v e f a c e - c e n t r ed c u b i c s y m m e t r y .


5/6

Transition Met. Chem., 2 0, 4 1 7 - 4 2 2 1 9 9 5 )

T ab l e 5 . Var i ab l e - tempera t u r e magne t i c m ome nt s o f do ub l e

compl ex sa l t

1)

Tem p. /~ Te mp . /~

K) B.M:) K) B.M.)

5.00 3.159 69.92 3.128

6.99 3.085 74.91 3.143

8.99 3.048 79.88 3.157

10.99 3.030 84.86 3.171

13.00 3.017 89.86 3.185

15.00 3.012 94.83 3.199

17.00 3.009 99.82 3.212

19.00 3.008 109.85 3.240

21.00 3.008 119.81 3.266

23.00 3.009 129.80 3.296

25.09 3.013 139.81 3.322

27.09 3.017 149.73 3.347

29.09 3.021 159.74 3.372

31.10 3.025 169.73 3.398

33.07 3.029 179.68 3.423

35.08 3.033 189.69 3.448

40.06 3.051 199.67 3.471

45.04 3.063 219.71 3.517

50.00 3.072 239.66 3.560

55.00 3.088 259.66 3.599

59.95 3.101 279.60 3.640

64.92 3.114 299.50 3.681

D o u b l e c o m p l e x s a l ts o f c y c l ic d i a m i n e l i g a n d s 4 2 1

Table 6. E .p.r . spect ra l para me ters for 1) at different tempera-

tures

T emp. gii g~ gay

K)

298 2.21 2.12 2.15

77 2.20 2.12 2.15

4 - 2.14

t u r e a n d t e n d s t o a p e r f e c t c r y s t a l s y s te m . I n t e g r a t i o n o f t h e

e . p . r , s p e c t r a i n d i c a t e s t h a t a l l t h e c o p p e r i s p r e s e n t a s

c o p p e r I I ) . T h e g v a l u e s s u p p o r t t h e p r e s e n c e o f f o u r a n d

f i ve coo rd i n a t ed cop per I I ) 24-27).

O n h e a ti n g , a ll th e c o m p l e x e s d e c o m p o s e b y d e h y d r a -

t i o n , s h o w i n g m a s s l o s s in t .g . a, c u r v e s a n d e n d o t h e r m i c

p e a k s i n d . t. a , c u r v e s F i g u r e 1 , T a b l e 3). F o r t h e d e c o m -

p o s i t i o n p r o c e s s m a s s l o s s in t h e t . g .a , c u r v e c o r r e s p o n d s

t o t h r e e m o l e c u l e s o f cy c l ic d i a m i n e i n c o m p l e x e s 1 ) -

3) .

T h e i n t e r m e d i a t e p r o d u c t i n e a c h c a s e w a s i s o l a t e d

b y k e e p i n g t h e r a t e o f h e a t i n g a t 1 ~ i n t h e r e s p e c ti v e

m a x i m u m d e c o m p o s i t i o n t e m p e r a t u r e . T h e i .r. s p e c t ra

s h o w t h a t t h e c y c l ic d i a m i n e s i n th e i n t e r m e d i a t e c o m -

p l e x e s e x i st in t h e c h a i r f o r m a s t h e n u m b e r o f i.r . a c t i v e

b a n d s b e t w e e n 7 0 0 a n d 1 4 00 c m - 1 i s l es s t h a n t h a t i n th e

. ~ a )

V

i

1000 2000 3000 4000 5000 6000

[ ]

b)

c)

F i g u r e 4 . E . p .r . spect ra of compound I ) a t a ) 2 9 8 K ; b ) 7 7 K ; and

c) 4 K.

W e t h e r e f o r e t e n t a t i v e l y c o n c l u d e f r o m t h e e . p . r , s p e c t r a

t h a t s o m e d i s t o r ti o n a p p e a r s i n t h e a n io n i c p a r t o f t h e

c r y s t a l s y s t e m d u e t o i n s e r t i o n o f l i g a n d i n t h e c o p p e r I I )

i o n w h i c h g r a d u a l l y d e c r e a se s w i t h l o w e r i n g o f t e m p e r a -

NC

CN

I e I

J

NC . . . . ~ . . . . CN

C 84

N

F i g u r e 5. Prop osed structure of the anion.

2 -


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Transition Metal Chemistry Volume 20 Issue 5 1995 [Doi 10.1007%2Fbf00141508] Parimal Kundu; Samiran...

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