MÖSSBAUER AND MAGNETIC PROPERTIES INVESTIGATION OF THE SPIN STATES IN 2 OR 3-PYRIDYL IMINE COMPLEXES ON IRON (II) DICHLORIDE

HAL Id: jpa-00218497

https://hal.archives-ouvertes.fr/jpa-00218497

Submitted on 1 Jan 1979

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.

MÖSSBAUER AND MAGNETIC PROPERTIES INVESTIGATION OF THE SPIN STATES IN 2 OR

3-PYRIDYL IMINE COMPLEXES ON IRON (II) DICHLORIDE

H. Wei, L.-R. Leu

To cite this version:

H. Wei, L.-R. Leu. MÖSSBAUER AND MAGNETIC PROPERTIES INVESTIGATION OF THE

SPIN STATES IN 2 OR 3-PYRIDYL IMINE COMPLEXES ON IRON (II) DICHLORIDE. Journal

de Physique Colloques, 1979, 40 (C2), pp.C2-355-C2-357. �10.1051/jphyscol:19792126�. �jpa-00218497�

JOURNAL DE PHYSIQUE Colloque C2, supplkment au no 3, Tome 40, mars 1979, page ~ 2 - 3 5 5

MOSSBAUER AND MAGNETIC PROPERTIES I N V E S T I G A T I O N OF THE S P I N STATES I N

2

^OR

3-PYRIDYL

IMINE COMPLEXES ON I RON ( I I DI CHLORIDE

H.H. Wei and L-R. Leu

Department o f Chemistry, Tamkang CoZZege of Arts and Sciences, Tamusui, Taiwan, Republic o f China Rbsum6.- Le present travail traite des spectres Kgssbauer et des propribtbs magndtiques de complexes hexacoordinbs de dichlorure de Fe(I1) avec des groupements NRp = CsHrNCRl (Ri = H, CH3, C6Hs;

R* = c ~ H ~ , C ~ H ~ C H ~ , c ~ H ~ c ~ ) . Pour les complexes 2-pyridyl imine, l'btat 6lectronique fondamental du Fe(I1) passe de l'btat haut spin 1 un &tat de spin interm6diaire quand H est remplacb par CH3 ou C6H5.

Cependant, le remplacement de C6H5 par CeHrCH3 ou C6H4C1 n'a pas d'effet sur l'6tat de spin de Fe(I1).

De plus, les spectres I&ssbauer se composent de deux doublets de d6placements isodriques voisins et d'effets quadrupolaires doubles l'un de l'autre. Ceci suggsre que les stereoisom2res cis. et trans.

sont prdsents 1 basse temp6rature. Les complexes 3-pyridyl imine de Fe(I1) sont tous deux 1'6tat haut spin pour tous les substituants des groupes R1 et R2.

Abstract.- The present work is concerned with Mgssbauer spectra and magnetic properties of some six- coordinated complexes of Fe(I1) dichloride with bis-diimine (2 or 3-pyridyl imines, CSHI,NCR~= NRp;

R~ = H, CHJ, C ~ H S ; ~p = C6H5, C6H4CH3, C6HkC1). For the 2-pyridyl imine complexes, the electronic ground state of Fe(I1) changed from high-spin state to the intermediate-spin state when H is replaced by CH3 or C6H5 at Rl. However, we found no effects of the replacement of CsHs by CeHrCH3 or C6H4C1 at Rp on the spin state of Fe(I1).

In addition, ~Sssbauer spectra showed two doublets with about 1:2 ratio of quadrupole splittings and similar isomer shifts. This suggests that the cis- and trans-stereoisomers are present at low tempera- ture. The 3-pyridyl imine complexes of Fe(I1) are all in the high-spin state for any substituents in R1 and Rp groups.

1. Introduction.- Miissbauer and magnetic studies on phere. The ligand of pyridyl imine derivatives the spin states of substituted N-(2-pyridylmethylene) (0.005 mole) in 10 ml absolute ethanol is added to a imine (Py-CH=NR) complexes of Fe(I1) have been made solution of ferrous chloride hydrate (0.025 mole) in by several workers 11-31. These reports demonstrated 5 ml absolute ethanol and dried under vacuum.

that the spin equilibrium of high-spins low-spin The characterization of the compounds was car- transition of Fe(I1) existed in some substituents R ried out by elemental analysis and IR spectrometry.

imine complexes of Fe(II).However, the substituent A newport MK.II.Gouy Balance was used in order to effect on the spin states of Fe(I1) atoms for 2 or obtain the magnetic moments.

3-pyridyl imine complexes such as CsHrNCRl- NRp has The ~gssbauer spectra of the complexes were not been known. observed with 57Co(C~) as source at 78, 202, and AS shown in the preceding paper /5/, 2-substi- 298 K. A constant acceleration type spectrometer tuted pyridylketone coordinates as a bidentate, (Austin s-600) was used in the present work. The iso- while the 3 or 4-pyridylketone acts as a monodenta- mer shifts were relative to the center of a sodium te. The Miissbauer spectra of the Fe(1I) complexes of nitroprusside doublet.

these two ligands are quite different each other.

The present work is concerned with Mgssbauer spectra and magnetic properties of the complexes of Fe(I1) dichloride with bis-diimine (2 or 3-pyridyl imines; py-CRl = M p , Ri = H, CHJ, C6Hs; R2 = CsHs, C6HsCH3, CsHsC1). Here, the attention is foccussed on the influence on spin states of the substituent Rl and Rp in the pyridyl imine ligands and further on the nature of Fe(I1) ion in the two different coordinating type of 2 and 3-position substituted pyr idyl imines

.

2. Experimental.- All the 2 or 3-pyridyl imine com- plexes of Fe(I1) are prepared under nitrogen atmos-

3. Results and discussion.- The most IR absorption bands of C=N streching in the complexes were located in the range of 1570-1650 cm-'. It was found that the alkyl vC=N streching frequencies in 2-pyridyl imine complexes shifted to lower (about 10-45 cm-') with respect to the free ligand, and that the shifts were not significant in 3-pyridyl imine complexes. From these facts, it was shown that the 2-pyridyl imine ligand acts as a bidentate and that the 3-pyridyl imine ligand acts as a monodentate. Consequently, the coordinating forms may be represented as follo- wing formula :

Article published online by EDP Sciences and available at http://dx.doi.org/10.1051/jphyscol:19792126

JOURNAL DE PHYSIQUE

b i c o c t a h e d r a l , t r i p l e t ground s t a t e may b e s t a b i l i - z e d / 8 , 9 / . The s p i n s t a t e o f F e ( I 1 ) i n t h e complexes

o f Fe(py-2-C(Me)=NR2)2C12 and Fe(py-2-C(Ph)=NR2)2Cl~

-Rl

^{i s} t r i p l e t , S=l i n d i s t o r t e d o c t a h e d r a l symmetry.

The e f f e c t i v e m a g n e t i c moments a r e g r e a t e r t h a n t h a t p r e d i c t e d from t h e s p i n o n l y e q u a t i o n ( 2 . 8 3 B.M. f o r

Fe

S = l ) . T h i s w i l l b e a s c r i b e d t o a l a r g e o r b i t a l con- t r i b u t i o n t o m a g n e t i c moments. I n a d d i t i o n , a t low The t y p i c a l Mossbauer s p e c t r a o f t h e complexes t e m p e r a t u r e ( F i g . I ) , t h e s p e c t r a o f t h e s e complexes a r e shown i n F i g u r e 1 . The m a g n e t i c moments and showed two d o u b l e t s w i t h a b o u t 1:2 r a t i o o f quadru- bf6ssbauer p a r a m e t e r s a r e l i s t e d i n T a b l e I . I n a com- p o l e s p l i t t i n g s and s i m i l a r i s o m e r s h i f t s . T h i s p a r i s o n o f t h e p r e s e n t d a t a l i s t e d i n T a b l e I w i t h s u g g e s t s t h a t c i s - and t r a n s - i s o m e r s a r e p r e s e n t a t t h o s e of Fe ( d i i m i n e ) z X 2 complexes r e p o r t e d previous- 78 K, and t h a t 2 - p y r i d y l e t h y l i d e n e o r b e n z y l i d e n e l y / 6 , 7 / , t h e f o l l o w i n g f a c t s were found. F o r t h e i m i n e complexes o f F e ( I 1 ) e x i s t s i n a c i s - form 2 - p y r i d y l i m i n e complexes, t h e e l e c t r o n i c g r o u n d (C,, symmetry) a t room t e m p e r a t u r e .

s t a t e o f F e ( I 1 ) changed from h i g h - s p i n s t a t e t o t h e We c o n c l u d e t h a t t h e s u b s t i t u e n t o f R1 i n t h e i n t e r m e d i a t e - s p i n s t a t e when H i s r e p l a c e d by C H 3 2 - p y r i d y l i m i n e complexes seem t o p l a y a n i m p o r t a n t

o r C6H5 a t R1. r o l e i n t h e a c t i o n o f c h a n g i n g s p i n - s t a t e and of

However, we found no e f f e c t s o f t h e r e p l a c e - d i s t o r t i n g c r y s t a l f i e l d symmetry o f F e ( I 1 ) . For t h e ment o f C6Hs by CsHbCH3 o r C6HbC1 a t R2 on t h e s p i n m o n o d e n t a t e 3 - p y r i d y l i m i n e complexes o f F e ( I I ) ,

s t a t e o f F e ( I 1 ) . Mijssbluer d a t a and m a g n e t i c moment show t h a t t h e y

F o r t h e c a s e o f s p i n t r i p l e t s t a t e , S = l , i f a r e a l l i n t h e h i g h - s p i n s t a t e f o r any s u b s t i t u e n t s t h e symmetry o f t h e c r y s t a l f i e l d i s lower t h a n cu- i n R1 and R2 g r o u p s .

T a b l e I : Mossbauer p a r a m e t e r s and m a g n e t i c moments f o r t h e complexes

1 1 I

:ueff(B.M.): 6 ( m / s ) * I I A E ~ (m/s)'*

Compound t---L---

:

^{295 K}

1

78 K 202 K

:

^{295 K}

:

^{78 K 202 K 295 K}

*

E r r o s , 0 . 0 2 mm/s. ^f% E r r o s ,

+

^{0 . 0 3} m/s. 8 two d o u b l e t s a r e p r e s e n t a t low t e m p e r a t u r e .

- ^-

^{1 0} Velocity (mm/s ¹ 1 ^{2 I 3}

^-

Fig. I : &ssbauer s p e c t r a of p y r i d y l imine complexes

of i r o n ( I 1 ) d i c h l o r i d e a t 7 8 K.

Acknowledgment.- We wish t o e x p r e s s o u r s i n c e r e g r a t i - tude t o The National Science Council, Republic of China f o r t h e f i n a n c i a l s u p p o r t of t h i s r e s e a r c h

References

/ 1 / Renovitch. G.A. and Baker Jr, W.A., J . Am. Chem. Soc.

89 (1967) 6377.

-

/ 2 / ~ g n i g , E., R i t t e r , G. and Schnkkig, R., Chem. Phys.

L e t t e r s ,

11

(1974) 2 3 .

/3/ Maeda, Y . , Takashima, Y. and Nishida, Y., B u l l . Chem.

Soc. Japan,

2

(1976) 2427.

/ 4 / E r s l i n g , J., F l e i s c h , J . and G i t l i c h , P., Chem. Phys.

L e t t e r s ,

65

(1977) 2 2 .

Wei, H.H. and Men, L.C., J . Inorg. Nucl. Chem., (1978) 221.

161 Kgnig, E. and Medeja. K., Inorg. Chem.,

5

(1967) 48.

/ 7 / ~ g n i g . E. and Watson. K . J . and Hedeja, K., J . Am.

Chem. Soc.,

90

(1968) 1146.

/ 8 / Kgnig, E. and Kanellakopulos, B., Chem. Phys. L e t t e r s , 12 (1972) 485.

-

/ 9 / ~ g n i g , E. and Giitlich, P. and Link, R . , Chem. Phys.

L e t t e r s ,

15

(1972) 3 0 2 .