HAL Id: jpa-00219597
https://hal.archives-ouvertes.fr/jpa-00219597
Submitted on 1 Jan 1980
HAL is a multi-disciplinary open access archive for the deposit and dissemination of sci- entific research documents, whether they are pub- lished or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers.
L’archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d’enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.
COMBINED 57Fe AND 129I MÖSSBAUER STUDY OF Fe (ALKYL DITHIOCARBAMATE) 2X (X = Cl,
I).
V. Marathe, A. Trautwein, A. Kostikas
To cite this version:
V. Marathe, A. Trautwein, A. Kostikas. COMBINED 57Fe AND 129I MÖSSBAUER STUDY OF Fe
(ALKYL DITHIOCARBAMATE) 2X (X = Cl, I).. Journal de Physique Colloques, 1980, 41 (C1),
pp.C1-315-C1-316. �10.1051/jphyscol:19801115�. �jpa-00219597�
JOURNAL DE PHYSIQUE Colloque C1, supplt?ment au
n o
1 , Tome 41, janvier 1980, page C1-3 15COMBINED 5 7 ~ e
AND
129 I MSSBAUER STUDY OF Fe (ALKYL DITHIOCARBME)~X (X = C1,
I ) IV.R. M a r a t h e , A . T r a u t w e i n , A. K o s t i k a s +
Universitiit des Saarlandes, 66 Saarbriicken 11, W-Germany.
+
Nuclear Research Center Demokritos, Athens, Greece.E x t e n s i v e i n v e s t i g a t i o n s o f t h e group of Fe (111) ( a l k y l d i t h i o c a r b a m a t e ) 2X comlexes
( X = C l , B r , I ) by Mdssbauer s p e c t r o s c o p y 1 a s
w e l l a s o t h e r s p e c t r o s c o p i c
have y i e l d e d a l a r g e amount of d a t a on t h e e l e c t r o n i c s t r u c t u r e of t h e F e ( I I 1 ) i o n . T h i s c o l l e c t i o n o f d a t a i n c o n j u n c - t i o n w i t h t h e low m o l e c u l a r symmetry (CZv) makes t h e s e complexes a n a t t r a c t i v e s y s t e m f o r t h e a p p l i c a t i o n o f c o m p u t a t i o - n a l models f o r t h e e l e c t r o n i c s t r u c t u r e . A c r y s t a l f i e l d model h a s b e e n a p p l i e d t o t h i s p r o b l e m by Ake e t a 1 4 ; i t i s d i f f i - c u l t t o e x p l a i n , however, t h e h i g h qua- d r u p o l e s p l i t t i n g i n t h e framework o f a c r y s t a l f i e l d model s i n c e t h e e l e c t r i c f i e l d g r a d i e n t (EFG) a r i s i n g from t h e 3d v a l e n c e e l e c t r o n i n a q u a r t e t s t a t e i s z e r o . I t was p o i n t e d o u t by d e V r i e s e t a 1 5 t h a t c o v a l e n c y d i f f e r e n c e s i n t h e v a r i o u s i r o n a t o m i c o r b i t a l s a r i s i n g from t h e low m o l e c u l a r symmetry may a c c o u n t f o r t h e l a r g e EFG, and t h i s s u g g e s t i o n was s u b s t a n t i a t e d by a m o l e c u l a r o r b i t a l c a l c u l a t i o n on F e ( d t ~ ) ~ C l . We p r e s e n t i n t h i s p a p e r r e s u l t s o f m o l e c u l a r o r b i t a l c a l c u l a t i o n s f o r two c a s e s o f h a l i d e li- gands ( X = C l , I ) and v a r i o u s c h o i c e s o f t h e d i t h i o c a r b a m a t e l i g a n d end g r o u p s . Hyper- f i n e f i e l d s and e l e c t r i c f i e l d g r a d i e n t s a r e c a l c u l a t e d from t h e MO wave f u n c t i o n s and compared w i t h e x p e r i m e n t a l r e s u l t s . The c a l c u l a t i o n o f m o l e c u l a r o r b i t a l s
(MOs)
yiMO
i s b a s e d on t h e s e m i e m p i r i c a l I t e r a t i v e Extended Huckel Theory (IEHT) 6.
The a t o m i c p a r a m e t e r s ( i o n i z a t i o n p o t e n - t i a l s and o r b i t a l e x p o n e n t s ) , which a r e n e c e s s a r y f o r t h e s e c a l c u l a t i o n s h a v e b e e n d e s c r i b e d p r e v i o u s l y 7 . The t y p i c a l c o n v e r g e n c e l i m i t o f t h e s e l f c o n s i s t e n t c h a r g e p r o c e d u r e i s 0.02 e .
F i g . 1 shows t h e m o l e c u l a r model f o r Fe
( d i e t h y l d i t h i o c a r b a m a t e ) 2X ( a b r e v i a t e d by F e ( d t ~ ) ~ X ) which h a v e b e e n u s e d f o r o u r MO s t u d i e s
*.
A s r a d i c a l s R b e i n g a t t a c h e d t o t h e d i t h i o c a r b a m t e s we have u s e d C 2 , H , C H 3 , and C 2 H 5 . T y p i c a l M O s ( f o r R=H) a r e r e p r e - s e n t e d by F i g . 2 , i n d i c a t i n g t h e d i f f e r e n t amount o f c h a r g e and s p i n t r a n s f e r i n Fe( d t c ) 2 C 1 compared t o Fe ( d t c ) 21. The r e p r e - s e n t a t i o n of t h e r a d i c a l s R by C21eads t o u n r e a l i s t i c MO r e s u l t s . I t i s i n t e r e s t i n g t o n o t e t h a t t h e r e p l a c e m e n t o f R by e i - t h e r H , C H 2 o r C2H5 does n o t l e a d t o d r a - s t i c c h a n g e s i n - t h e c a l c u l a t e d r e s u l t s . T h e measured and c a l c u l a t e d Mbssbauer v a l u e s a r e summarized i n t h e t a b l e . The s l i g h t d i s a g r e e m e n t of c a l c u l a t e d and measured
4 E
(Fe) and q ( F e ) v a l u e s f o r F e ( d t c ) 2 I m i g h t b e due t o p o s s i b l e c l u s t e r i n g o f FeQ
( d t ~ ) ~ I i n t o d i m e r s , which h a s n o t b e e n c o n s i d e r e d i n t h e p r e s e n t c a l c u l a t i o n s . The f o r e g o i n g r e s u l t s show t h a t t h e semi- e m p i r i c a l IEHT r e p r o d u c e s s a t i s f a c t o r i l y s e v e r a l p a r a m e t e r s o f t h e e l e c t r o n i c s t r u c t u r e o f t h e Fe ( d t c ) 2X c o m p l e x e s , T h i s i n c l u d e s t h e m a j o r f e a t u r e s t h a t were men- t i o n e d e a r l i e r , namely a n e n e r g y l e v e l scheme f o r 3 d - l i k e o r b i t a l s which f a v o r s a S=3/2 s t a t e and t h e l a r g e q u a d r u p o l e s p l i t - t i n g , b u t i t e x t e n d s a l s o t o o t h e r impor- t a n t f e a t u r e s a s t h e n a t u r e o f t h e i r o n - h a l o g e n bond and m a g n e t i c h y p e r f i n e i n t e r - a c t i o n .
1 . Wickman, H.H., T r o z o l l o , A.M., W i l l i - ams, H . J . , H u l l , G . W . , M e r r i t t , F . R . , Phys. Rev.
155,
(1967) 5632 . B r a c k e t t , G . C . , R i c h a r d s , P . L . , Caugby W.S., J . Chem. Phys.
54,'
(1971) 4383 3. Wickman, H . H . , M e r r i t t , F.R., Chem.Phys. L e t t .
1,
(1967) 1174 . Ake, R . I . , Harris-Loew, G.M., J. Chem.
Phys.
2,
(1970) 10985. d e V r i e s , J.L.K.F., K e i j z e r s , C..P., 22
Article published online by EDP Sciences and available at http://dx.doi.org/10.1051/jphyscol:19801115
c1-316 JOURNAL DE PHYSIQUE
deBoer, E., Inorg. Chem. 2, (1972) 1343
6. Cusachs, L.C., Reynolds, J.W., J. Chem. i 3z2-r2 xi x2-y2 yz XY Phys. 43, (1965) S160
7. Reschke, R., PhD-Thesis, Universitat des Saarlandes , W-Germany (1 976)
8.
Healy, P.C., White, A.H., Hoskins, B.E.
J. Chem. Soc. (Dalton) (1972) 1369 9. Petridis, D., Simopoulos,
A , ,Kostikas,
A., Pasternak, M., J. Chem. Phys. 65,
(1976) 3139
lo.Reschke, R., Trautwein, A,, Theoret.
Chim. Acta 47, (1978) 85
Supported by Deutsche Forschungsgemein- schaf t .
Table I : Experimental and calculated M6ssbauer parameters for
57
F e and 12%.cii3 u + z "CH3
Fig. 1
:Fe(dt~)~X, with X=Cl,I, the cartesian coordinates of which have been
assb.uer .r..ctcrs
taken from ref. -
8.Fo(dts1 C1 f o r STF:
cxp(') I s a l
~ e ( d t c I ~ 1 f o r s 7 ~ e for. l Z 9 1
0: ligond 0::
exp(') 1c.l
I 7 ligand orbilals.
doubly occuped
oxp{*) I s.1
Fig. 2: Molecular orbitals @p Y?
=5 'pi
of mainly iron character as obtai-
i c j I ( L I = ~ I Y C t o zfle
(d) Calculated fro. ;he s ~ m i c m p f r i c ~ t r c l ~ t i m dcrcrxbrd by H . dc M o r d In
"MOssbaucr E I f ~ c t Data Index'. 1973, p 447
(e) Includes valence- overlap-. and lzgand-co;tributionr f o r i r o n accordrnp
~ ~ ~ ~ : $ v ~ < ~ ~ b ~ ~ 1 n ~ ~ : :%% ~ i ~ d ~ ~ % ' ~ ~ ~ ~ : i k ~ ~ 2 ~ ~ ~ ~
( f ) For f u r t h e r s a l c u l a t i o n a l d e t a i l s see 'Illsrbaucr S p s t r o a c o p y and Tran- s i t i o n Metal hemxstry". Springer-Verlag. 1978,scstion VI.
i n t ( 1 i n r e l l *
ned from IEHT calculations. Values C /cci without and with brackets correspond to Fe (dtc) 2C1 and Fe (dtc) 21, respectively.
(a) Taken from refs. 1 and 9.
l b l Relmtivc t o 01 -Fe.
31.9 t1.o
, 17.2 f 0
22.4
19.6 5 . 3 t o 5.1 6.7
