PARTIAL QUADRUPOLE SPLITTING OF Fe-57 SPECIES PRODUCED FROM Co-57-LABELLED WERNER COMPLEXES

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PARTIAL QUADRUPOLE SPLITTING OF Fe-57 SPECIES PRODUCED FROM Co-57-LABELLED

WERNER COMPLEXES

Y. Sakai, M. Harada, K. Endo, H. Sano

To cite this version:

Y. Sakai, M. Harada, K. Endo, H. Sano. PARTIAL QUADRUPOLE SPLITTING OF Fe-57 SPECIES

PRODUCED FROM Co-57-LABELLED WERNER COMPLEXES. Journal de Physique Colloques,

1979, 40 (C2), pp.C2-431-C2-433. �10.1051/jphyscol:19792151�. �jpa-00218525�

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JOURNAL DE PHYSIQUE Colloque C2, suppl6ment au n O 3, Tome 40, mars 1979, page C2-43 1

PARTIAL

QUADRUPOLE SPLITTING OF ~ e - 5 7 SPEC!ES PRODUCED FROM

CO-57-LABELLED WERNER

COMPLEXES

Y. Sakai, M. Harada, K. Endo and H. Sano

Department of Chemistry, Faculty o f Science, Tokyo MetropoZitan University, Fukusawa, Setagaya, Tokyo, Japan 158.

R6sumd.-Les valeurs de l'effet quadrupolaire rdsultant du processus 5 7 ~ o ( ~ ~ ) 5 7 ~ e ont Btd mesurdes dans des composds de coordinences variBes du type Werner marquBs au 5 7 ~ o . Une des deux composantes trouv6es dans le spectre Mgssbauer dlBmission a dtd attribude 1 des Btats haut spin produits aprls le processus de conversion Blectronique. L'autre composante a dtd attribude B des Btats 5 7 ~ e ( ~ ~ ~ ) . Abstract.- The quadrupole splittin values of the species produced from 'the 5 7 ~ o ( ~ ~ ) 5 7 ~ e process were investigated in the various 58Co-labelled Werner-type co-ordination compounds. One of the two components of the decayed species found in the emission Mijssbauer svectra was assigned to high-spin species of Fe(I1) pr_oduced after the EC-decay based on their large quadrupole splittings and isomer shifts. The other component was ascribed to co-ordinated 5 7 ~ e ( ~ ~ ~ ) species, since the quadrupole splittings of the species were well represented by using the partial quadrupole splitting of each ligand.

A number of efforts have been devoted to in- vestigate the chemical effect associated with the EC decay process in 7 ~ o (111) co-ordination compounds.

It is generally recognized that the high spin 5 7 ~ e (11) species are produced when 5 7 ~ o decays to 5 7 ~ e through the EC decay in the low spin Co(II1) Werner complexes /l/. However, it may also be expected that the low spin Fe(II), low spin Fe(II1) and high spin Fe(II1) species be produced through the process.

Bancroft et al. /2/ have studied on the systematics of the quadrupole splitting (QS) of the low spin Fe(I1) Werner complexes and shown that the QS values are given by adopting the concept of the partial quadrupole splitting (PQS) of each ligand. In the present work, the chemical states of 5 7 ~ e species produced from 7 ~ o (111) complexes are examined on the basis of the concept of PQS.

1. Experimental-.- 57~o-labelled complexes were pre- pared from solutions containing about 50 mg of Co(I1) and about 0.5 mCi of carrier-free 5 7 ~ o according to the literature 1 3 1 . The source materials were kept in a cryostat at the liquid nitrogen temperature and the emission Gssbauer spectra were measured agains.t an 57~e-enriched stainless steel absorber moving in a constant acceleration mode at room temperature.

2. Results and discussion.- The PQS value of a ligand is expressed as follows :

PQSL = 112 eQ p/r3

where e is protonic charge; Q, quadrupole moment of nucleus; p, charge density of ligand in point charge

model; and r, distance between nucleus and ligand in point charge model. The QS values of MAB5 type-trans- MA2B4 type- and cis-MAzBt, type-Werner complex can be expected to be 2(PQSA

-

^PQSB^),^4(PQSA

-

^{PQSB) and}

-2(PQSA

-

PQSB), respectively. The ratio of the ma- gnitude~ of QS of these three complexes is predicted to be 1:2:1. Typical emission Mgssbauer spectra are shown in figure 1.

-

² ⁰ ² ⁴

Velocity (mm/s)

Fig. 1 : Typical emission Mijssbauer spectra of 5.7~o (111)-Werner CO-ordi ation compounds; a, trans-

1'

^'CO

(Non) (NH~)~]NO~; b,Ts7co(~z0) (NHS) 51 (No31 3;

c, K ~ ~ ~ ~ C O C L ( C N ) 51

.

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Article published online by EDP Sciences and available at http://dx.doi.org/10.1051/jphyscol:19792151

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JOURNAL DE PHYSIQUE

Table I : Miissbauer parameters of component A

57~o-labelled complex I S Value (mm/s) QS Value (mm/s) [ 57 Co(N02) (NH3)

5 l

(NO3) 2 0.50

t

0.08 0.56

+

^0.08

cis-

[ 5 7 ~ o ( ~ 0 2 ) (NH3) 41C1 0.61

+

^0.08 ^0.60

+

^0.08

trans-

[ 5 7 ~ ~ (No2) (NH3) 41N03 0.47 f 0.08 l.i4

2

^0.08

[ 5 7 ~ ~ ( ~ 2 0 ) (NH3)

5 1

(NO3) 0.51 f 0.08 1.01

+

0.08

I

57 CO (CH3COO) (NH3) 5] (NO3) 0.34 f 0.08 1.05

+

^0.08

K, [ 5 7 ~ o ~ 1 (CN)

,l

-0.44

t

^0.08 ^1.94

+

0.08

The M6ssbauer parameters of the inner component A of the spectra are listed in table I. The ratio of QS values of [57~o(~02) (NHS) 51 trans-

[57~o(~02)2 ( N H ~ ) I + ~ N O ~ and c ~ s - L ~ ~ c o ( N o ~ ) ~ ( M I ~ ) ~ ; ] c ~ was found to be almost 1 : 2 : 1 . The ratio was almost

I : 1 in the case of [57~o(~20) (NH3) 51 (NOS) 3 and cis- [57~o(~20) 2 (NH3)

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cl3 as seen in table I. These results suggest that the QS values of component A are given by PQS of each ligand, i.e. that bhe 5 7 ~ e species corresponding to component A have a Werner type co-ordination structure with the same composi- tion and arrangement of ligands as in the parental 5 7 ~ o ( ~ ~ ~ ) complex. On the other hand, the IS and QS values of the outer component B were nearly the same for all the "CO complex sources, indicating the component B is ascribable to high spin Fe(1I) species. Figure 2-a shows the relationship between the QS values in table I and the QS values predicted by using the PQS of Fe(I1) low spin state reported by Bancroft et al., assuming that the species of component A are low spin Fe(I1) Werner complexes with the parental ligand-arrangement. Although there seems to be a definite relationship between them, the QS values observed are quite different from those predicted for low spin Fe(I1) species. There- fore, the species A may not ascribable to low spin Fe(I1) Werner complex species. The PQS values of

CN-, NHs, NO;, H20, N; and Cl- ligand were estimated from the QS values measured and the plots of the values against the PQS values for low spin Fe(I1) species are shown in figure 2-b, where the PQS values of the ordinate were those re-evaluated relati- ve to that of Cl- ligand taking PQSCl = -0.3 mm/s, according to the normalization carried out for low spin Fe(I1) compounds by Bancorft et al. Fleisch and G'itlich/4/ have reported on the spin state in the s 7 ~ e species produced through the EC decay of

[

5 7 ~ o ( ~ ~ ~ ) ~ ( ~ h e n ) d that the emission spectra exclusively show the high spin Fe(I1) resonance whe- reas the corresponding Fe(I1) compound is known to be in the high- and low- spin equilibrium. As the pentamine and tetraamine iron(II1) co-ordination compounds are known to be in high spin state, it may be reasonable to conclude that the produced Fe(II1) species are in high spin state. The linear relationship found in figure 2-b suggests that the S 7 ~ e ( ~ ~ ~ ) species produced in the pentacyano 5 7 ~ o ( ~ ~ ~ ) complexes should also be in high spin state.

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QS Value (mm/s) expected for Fe (11) low spin

F i g . 2a : R e l a t i o n s h i p between QS v a l u e s measured and QS v a l u e s e x p e c t e d f o r low s p i n F e ( I 1 ) s t a t e .

PQS Value (mm/s) for Fe (11) low s p i n

F i g . 2b : R e l a t i o n s h i p between PQS v a l u e s o b t a i n e d and PQS v a l u e s r e p o r t e d f o r low s p i n F e ( I 1 ) s t a t e .

References

1 1 1 Sano, H. and Ohnuma, T . , B u l l . Chem. Soc. J a p a n 48 (1975) 266.

-

121 B a n c r o f t , G.M., Mays, M . J . and P r a t e r , B.E., J . Chem. Soc. (A) (1970) 956.

131 Nakahara, M. and S h i b a t a , M., Eds., Shin-Jikken- kagaku-koza,

8

Maruzen ( i n J a p a n e s e ) (1977).

141 F l e i s c h , J . and ~ i i t l i c h , P . , Chem. Phys. L e t t .

42

(1976) 237.