Optical Detection of the Lanthanoid Ion Contraction by Internal Charge

6 Optical Detection of the Lanthanoid Ion Contraction by Internal Charge-Transfer Absorption of Rare Earth Bisporphyrinate Double-deckers J. W. Buchler, K. Elsässer, M . Kihn-Botulinski, B. Scharbert, and S. Tansil

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Institut für Anorganische Chemie, Technische Hochschule Darmstadt, D-6100 Darmstadt, Federal Republic of Germany

The optical spectra of a series of lanthanoid bis-(octaethylporphyrinates), Ln(OEP) (Ln = La...Nd, Sm...Lu) are reported. All compounds have a doubledecker structure. Apart from the Ce derivative, all the other representatives contain Ln ions and a defect electron on one of the porphyrin rings and have the composition Ln (OEP) (OEP˙) . These "odd" species all have near infrared (NIR) internal charge transfer absorption bands between 1480 (La) and 1135 nm (Lu). The wavenumber of this band is inversely proportional to the radius of the rare-earth ion for the coordination number 8. The neutral Ce(OEP) can be oxidized to a radical cation which also has a NIR band at 1270 nm. 2

IV

III

3+

2-

-

2

A complete s e r i e s o f l a n t h a n o i d b i s o c t a e t h y l p o r p h y r i n a t e s L n ( 0 E P )

2

(Ln = La...Lu, w i t h the e x c e p t i o n o f Pm) has been s y n t h e s i z e d , together with a s e r i e s o f b i s l a n t h a n o i d t r i s p o r p h y r i n a t e s L n ^ O E P ) ^ 2

(Ln = La...Gd) ( 2 , 3 , 4 ) . 2

2

( A b b r e v i a t i o n s used: ( O E P ) " ,

2

(TPP) ",

2

( T T P ) " , ( P c ) ~ and ( P ) " a r e t h e d i a n i o n s o f 2,3,7,8,12,13,17,18o c t a e t h y l p o r p h y r i n , 5,10,15,20- t e t r a p h e n y l p o r p h y r i n , 5,10,15,20-tetra(p-tolyl)porphyrin,

phthalocyanine,

and a g e n e r a l

p o r p h y r i n , r e s p e c t i v e l y . L, L n , M a r e g e n e r a l l i g a n d s ,

lanthanoids,

metals.) The complexes L n ( 0 E P ) ~ a l l c o n t a i n Ln*"'"* i o n s . A p a r t from t h e IV ?

d i a m a g n e t i c Ce

complex C e ( 0 E P )

2

( 2 ^ 3 ) , t h e complexes L n ( 0 E P ) a r e 2

NOTE: This is number 42 in the series Metal Complexes with Tetrapyrrole Ligands. 0097-6156/ 86/ 0321 -0094S06.00/ 0 © 1986 American Chemical Society

Gouterman et al.; Porphyrins ACS Symposium Series; American Chemical Society: Washington, DC, 1986.

6.

Optical Detection of the Lanthanoid Ion Contraction

BUCHLERETAL.

1

1

95

1

d e s c r i b e d as Ln" " " " complexes o f a d i n e g a t i v e p o r p h y r i n a t e and a mononegative p o r p h y r i n r a d i c a l w i t h a h o l e i n t h e X - e l e c t r o n system ( 2 ) . The c r y s t a l and m o l e c u l a r the parent

s t r u c t u r e s of Ce(OEP)

2

and C e ( O E P ) 2

3 >

s p e c i e s o f t h e two s e r i e s , have been determined and prove

the doubledecker and t r i p l e d e c k e r shapes o f t h e two s e r i e s , r e s p e c t i v e l y ( 3 ) . E s s e n t i a l s t r u c t u r a l parameters i n t h e doubledecker Ce(OEP)

2

(A) o r i n t h e t r i p l e d e c k e r C e ( O E P ) 2

3

(B) a r e

shown i n F i g u r e 1, which g i v e s t h e p r e v i o u s l y used bar graphs ( 5 , 6 ) t o r e p r e s e n t t h e c o n f i g u r a t i o n . Above t h e b a r s , t h e d i s t a n c e s o f t h e


mean p l a n e s o f t h e 20 C and 4 Ν c o r e atoms o f t h e i n d i v i d u a l porphyrinato Ce-N

l i g a n d s a r e quoted, a t t h e r i g h t o f t h e b a r s t h e mean

bond l e n g t h s a r e l i s t e d .

The mean v a l u e o f t h e s e bond l e n g t h s

i s 247.5 pm i n A^ and 263 pm i n jS, t h e l o n g e r d i s t a n c e i n t h e l a t t e r corresponding

t o t h e f a c t t h a t Β i s a Ce*** complex and j \ a Ce*^

complex. The Ce-N d i s t a n c e s i n Β d i f f e r f o r t h e two e x t e r n a l r i n g s on one hand and f o r t h e i n t e r n a l one on t h e o t h e r ; t h e i n t e r n a l has t o h o l d two cerium

ring

i o n s and t h e r e f o r e i s connected t h r o u g h

somewhat l o n g e r bonds. O p t i c a l A b s o r p t i o n S p e c t r a and E l e c t r o n i c S t r u c t u r e The

o p t i c a l spectra of a l l the doubledeckers are l i s t e d i n Table I .

On f i r s t g l a n c e , C e ( 0 E P )

2

has a "normal" spectrum ( 7 ) . However, t h e

spectrum shows e x t r a bands and t h e r e f o r e s h o u l d be c a l l e d "hyper". A s m a l l band appears a t 467 nm (maybe a l i g a n d - t o - m e t a l charge t r a n s f e r band), and broad f e a t u r e s extend f a r i n t o t h e near i n f r a r e d ( N I R ) . The l a t t e r a b s o r p t i o n may be due t o e x c i t o n i n t e r a c t i o n s . Contrary

t o t h e known r a r e e a r t h monoporphyrins ( 7 ) , i t has been

shown f o r t h e c l o s e l y r e l a t e d c e r i u m ( I V ) b i s ( t e t r a - p - t o l y l p o r p h y r i n a t e ) , Ce(TTP)

2

(8) that the doubledeckers

do n o t e m i t , and t h e i r e x c i t a t i o n i s d i s s i p a t e d v e r y r a p i d l y ( 9 ) . The

o t h e r d o u b l e d e c k e r s c o n t a i n i n g t h e m e t a l s L a , P r , Nd, Sm -

Lu have r a t h e r s i m i l a r s p e c t r a t h a t have l e s s w e l l d i s t i n c t bands i n the v i s i b l e r e g i o n . The e x t i n c t i o n a t 573 nm i s much l e s s t h a n i n Peaks occur a t about 540 and 670 nm. The l a t t e r a b s o r p t i o n i s t y p i c a l f o r Κ-cation Ln(0EP)

2

r a d i c a l s ( 1 0 ) . Indeed, t h e c o m p o s i t i o n

can o n l y be accomodated w i t h t h e normal t r i v a l e n t s t a t e o f

n e a r l y a l l o f t h e l a n t h a n o i d i o n s i f one assumes t h a t t h e


P O R P H Y R I N S : E X C I T E D STATES A N D D Y N A M I C S

96


—»| 354 |«-

I I/I

I I

0 262.9

I I I 374

43.8

Λ Y^

U

Ce(0EP)

g

1.

υ

Ce (0EP)3.2C H Cl3 2

A Figure

24.5

1

6

3

Β

Synopsis of the s t r u c t u r a l features

and Ce2(0EP)

3

(B). E s s e n t i a l distances

o f CeCOEP^ (A)

a r e g i v e n i n pm. Below t h e

bar graphs o f t h e doubledecker A and t h e t r i p l e d e c k e r B, t h e r e l a t i v e o r i e n t a t i o n s o f t h e p o r p h y r i n r i n g s i n A and Β a r e shown.


6.


BUCHLER ET A L .

Table

I.

97

E l e c t r o n i c Absorption Spectra of Lanthanoid B i s ( o c t a e t h y l p o r p h y r i n a t e s ) , L n ( O E P ) , i n c y c l o h e x a n e (A) 2

^max

i

n

n

m

'

l

o

9

e

in brackets,

Packard spectrophotometer


Complex La(ΟΕΡ) Ce(ΟΕΡ) Pr(ΟΕΡ)

NIR b a n d 2

1480

A]

UV/VIS b a n d s

(2. .75) —

2

Hewlett-

HP 84 51

576 (3.70)

540 (3.85)

494 (3.75)

394 (5.15)

661 (3.16)

573 (4.24)

530 (3.77)

467 (3.92)

378 (5.08)

2

1400

(3. 50)

670 (3.21)

576 (3.64)

540 (3.80)

490 (3.72)

391 (5.18)

2

1360

( 3 . 28)

668 (3.08)

577 (3.48)

542 (3.97)

488 (3.53)

390 (4.81)

2

1300

(3. 20)

674 (3.21)

578 (3.78)

544 (3.86)

489 (3.79)

390 (5.11)

2

1280

(3. 89)

676 (3.36)

543 (3.87)

376 (5.04)

2

1250

( 3 . 74)

674 (3.26)

542 (3.71)

380 (4.88)

Tb(OEP) ?

1237

( 3 . 49)

680 (3.30)

580 (3.70)

544 (3.81)

492 (3.80)

378 (5.00)

Dy (OEP) ?

1205

( 3 . 46)

679 (3.27)

582 (3.77)

546 (3.84)

494 (3.82)

386 (5.09)

Ho(OEP) 2

1182

( 3 . 65)

684 (3.24)

582 (3.83)

546 (3.91)

494 (3.89)

376 (5.10)

Er(OEP) 2

1175

( 3 . 68)

679 (3.24)

582 (3.67)

544 (3.79)

494 (3.78)

374 (5.06)

Tm(OEP) 2

1152

( 3 . 24)

672 (3.31)

584 (3.78)

546 (3.76)

494 (3.77)

388 (5.08)

Yb(OEP) ?

1144

( 3 . 83)

672 (3.21)

530 (3.76)

498 (3.75)

370 (4.98)

Lu(OEP)

1135

( 3 . 85)

674 (3.36)

534 (3.77)

490 (3.76)

370 (5.02)

Nd(OEP) Sm(OEP) Eu(OEP) Gd(OEP)

Cm


P O R P H Y R I N S : E X C I T E D STATES A N D

98

DYNAMICS

p o r p h y r i n a t o l i g a n d s occur i n d i f f e r e n t o x i d a t i o n s t a t e s , i . normal (OEP) ( 2 ) . The

e. a

d i a n i o n and a p o r p h y r i n r a d i c a l monoanion, (OEP") +3 -2 _

c o m p o s i t i o n may

then be d e s c r i b e d as Ln

(OEP)

T h i s i s e a s i l y seen from the paramagnetism of L u ( O E P ) magnetic moment of a r a d i c a l , i .

e. 1.7

(OEP*) . which has

2

the

Β. M. i n the s o l i d s t a t e

( 4 ) . As l u t e t i u m i o n s o t h e r than diamagnetic

f * ^ L u * * * are

not

known, o n l y a p o r p h y r i n r a d i c a l s t a t e i s l e f t t o e x p l a i n the p r o p e r t i e s . A s i m i l a r r a d i c a l s t a t e has been found f o r another


doubledecker

molecule,

lutetium bis(phthalocyaninate), Lu(Pc) , 3+ -2 ?

which i s hence t o be d e s c r i b e d as Lu Ln

doubledeckers

about 1550

furthermore

(Pc)

(Pc*)

(11»12). A l l the

show c h a r a c t e r i s t i c IR bands a t

cm * i n the IR s p e c t r a ( 2 , 4 ) , bands t h a t have been shown

t o be t y p i c a l f o r m e t a l l o p o r p h y r i n s w i t h e l e c t r o n - d e f i c i e n t porphyrin ligands (13). A p a r t from C e ( 0 E P ) , a l l the o t h e r doubledeckers 2

Ln(0EP)

each

2

have an e x t r a band of a molar e x t i n c t i o n c o e f f i c i e n t of about 10^ i n the near IR between 1200

and

1500

nm

(see T a b l e I and F i g u r e 2 ) .

T h i s band i s t y p i c a l f o r those b i s p o r p h y r i n s t h a t a r e e l e c t r o n - d e f i c i e n t i n one of the p o r p h y r i n r i n g s . I t i s absent i n Ce(TTP) , PrH(TTP) , NdH(TTP) 2

2

2>

and the a n i o n s o b t a i n e d

by

d e p r o t o n a t i o n of the l a t t e r two s p e c i e s (8,^14) as w e l l as i n a l l the t r i p l e d e c k e r s . We

t e n t a t i v e l y e x p l a i n i t as an i n t e r n a l charge

t r a n s f e r band: a r o m a t i c donor m o l e c u l e s acceptor

(EDA)

form c o p l a n a r e l e c t r o n donor

complexes w i t h a r o m a t i c a c c e p t o r s ; t h e s e

EDA

complexes have t y p i c a l a d d i t i o n a l bands a t l o n g e r wavelengths than the i n d i v i d u a l s e p a r a t e d components ( 1 5 ) . The geometry f i x e d by the sandwiched l a n t h a n o i d b u i l d s up a very e f f i c i e n t EDA complex from 2the donor, (OEP)

, and the a c c e p t o r , (OEP*) , t o which system then

belongs the NIR a b s o r p t i o n w i t h the r a t h e r h i g h e x t i n c t i o n c o e f f i c i e n t . (A f a c t o r d e c r e a s i n g the o v e r l a p w i t h i n the EDA i s c e r t a i n l y the s t a g g e r e d

complex

c o n f i g u r a t i o n of the p o r p h y r i n l i g a n d as

taken from F i g u r e 1 ( 3 ) . ) The NIR

band i s t h e r e f o r e c a l l e d

an

" i n t e r n a l charge t r a n s f e r " (CTI) band. The CTI band has n o t h i n g t o do w i t h the v a r y i n g f - e l e c t r o n c o n f i g u r a t i o n of the r a r e e a r t h i o n s . I f t h i s would be the c a s e ,


the

6.

B U C H L E R ET A L .

Optical Detection of the Lanthanoid Ion

99

Contraction

energy of t h i s band s h o u l d v a r y c h a r a c t e r i s t i c a l l y l i k e

the

f - e l e c t r o n s p e c t r a or the magnetic moments of the r a r e e a r t h i o n s . On the c o n t r a r y , a q u i t e s y s t e m a t i c b e h a v i o r w i t h the l a n t h a n o i d i o n c o n t r a c t i o n i s o b s e r v e d . A p l o t of the energy of CTI band v e r s u s i o n i c r a d i u s a t c o o r d i n a t i o n number 8 of the Ln

ions

the

(16)

i n d i c a t e s a l i n e a r decrease of t h i s energy as the i o n i c r a d i u s i n c r e a s e s . T h i s i s seen i n F i g u r e 3, and i l l u s t r a t e s a bare s i z e e f f e c t of the energy v a r i a t i o n . The

phenomenon i s c a l l e d

"optical

d e t e c t i o n of the l a n t h a n o i d i o n c o n t r a c t i o n by i n t e r n a l charge transfer absorption". Downloaded by TUFTS UNIV on November 25, 2016 | http://pubs.acs.org Publication Date: October 15, 1986 | doi: 10.1021/bk-1986-0321.ch006

2— The

complexes (P)

-Ln-(P*)

mixed-valence complexes (,17). The

c o u l d be regarded

as " i n v e r s e "

normal mixed-valence complexes,

e.g. M -L-M , c o n s i s t of two m e t a l s i n d i f f e r e n t o x i d a t i o n s t a t e s connected by a c e r t a i n b r i d g i n g l i g a n d . I n the i n v e r s e s i t u a t i o n , 21e.g.

L

-M-L

, two l i g a n d s i n d i f f e r e n t o x i d a t i o n s t a t e s a r e h e l d

t o g e t h e r by a b r i d g i n g m e t a l . M i x e d - v a l e n c e complexes have c h a r a c t e r i s t i c long-wave a b s o r p t i o n bands i n the v i s i b l e s p e c t r a . I t i s tempting

t o c l a s s i f y our systems a c c o r d i n g t o Hush's t h e o r y

mixed-valence complexes. They would belong

of

to Class I I ( o p t i c a l

s p e c t r a of c o n s t i t u e n t i o n s w i t h minor m o d i f i c a t i o n s and a d d i t i o n a l NIR

bands). However, the observed d i s t a n c e dependence of the

bands i s o p p o s i t e t o what would be expected by Hush's t h e o r y . NIR

NIR The

bands show a s o l v e n t dependence; a hypsochromic s h i f t i s

observed as the p o l a r i t y of the s o l v e n t i n c r e a s e s . T h i s means t h a t the complex cannot have a t o t a l l y s y m m e t r i c a l

electron distribution,

and hence, the e l e c t r o n i c " h o l e " cannot be c o m p l e t e l y the m o l e c u l e .

delocalized i n

P o s s i b l y the h o l e i s l o c a l i z e d on the NIR

one of the r i n g s , and NIR

timescale

e x c i t a t i o n moves the h o l e somewhat more

towards the o t h e r r i n g , but not c o m p l e t e l y

onto i t . Then the c e n t r a l

m e t a l i o n would r e p e l the moving charge the more the s m a l l e r metal-porphyrin

on

the

d i s t a n c e s become, i n a c c o r d w i t h the observed

situation. Another e x p l a n a t i o n f o r the e f f e c t of the l a n t h a n o i d i o n c o n t r a c t i o n on the energy of the NIR-CTI band may e x t e n t of doming of the p o r p h i n a t o

be found i n the

l i g a n d s i n the L n ( P )

2

structures.

A comparison of the i n c l i n a t i o n a n g l e s of the p y r r o l e u n i t s i n A_ and



100

= Gd(OEP)

2

= Sm(OEP) = Nd(OEP)

0.6

2

2

0.4

1250


0.2

0.0

1

600

800

F i g u r e 2. (

1200

1000

1400

1800

1600

Near i n f r a r e d s p e c t r a o f N d ( 0 E P ) (' 2

'),

Sm(0EP)

[nm]

2

-) i n c y c l o h e x a n e ( s e e T a b l e I ) .

) , and G d ( 0 E P ) (2

9000 CTI

Ln(OEP)

2

8000

7000

—ι 96

1

1

1

1

100

104

108

112

1— 116

120

[pm] F i g u r e 3. Ln(0EP)

9

P l o t o f t h e wavenumber (cm

( L n = Lu III

of t h e Ln

o f t h e NIR bands o f

L a ) as a f u n c t i o n o f t h e i o n i c r a d i u s (pm)

i o n s a t t h e c o o r d i n a t i o n number 8 ( " O p t i c a l

d e t e c t i o n o f t h e l a n t h a n o i d i o n c o n t r a c t i o n " by t h e CTI bands).


6.

101


BUCHLER ET AL.

B_ (see F i g u r e 1) w i t h r e s p e c t t o t h e mean plane o f t h e f o u r p o r p h i n a t o n i t r o g e n atoms l e a d s t o t h e c o n c l u s i o n t h a t these

angles

i n c r e a s e w i t h d e c r e a s i n g i o n i c r a d i u s o f t h e l a n t h a n o i d i o n and i n c r e a s i n g s t r e n g t h o f t h e L n - ( P ) bonds ( 3 , 4 ) . I n a g i v e n s e r i e s o f Ln(P)

2

complexes, t h e most pronounced doming o f t h e p o r p h i n a t o

s h o u l d occur i n t h e L u ( P )

2

core

system which, on t h e o t h e r hand, w i l l

have t h e s m a l l e s t Ln-N bond d i s t a n c e s . A s t r o n g e r outwards doming o f the p o r p h i n a t o l i g a n d s i n a L n ( P )

2

doubledecker

c o u l d then reduce

the i n t e r - r i n g charge t r a n s f e r i n t e r a c t i o n s d e s p i t e a decrease i n


the d i s t a n c e o f t h e mean p l a n e s o f t h e p o r p h i n a t o c o r e atoms and hence cause a hypsochromic s h i f t t o t h e CTI bands. T h i s i d e a has t o be t e s t e d by f u r t h e r c r y s t a l l o g r a p h i c s t u d i e s i n t h e L n ( P )

2

series.

A n a l o g i e s o f Rare E a r t h P o r p h y r i n Doubledeckers w i t h t h e S p e c i a l P a i r of B a c t e r i o c h l o r o p h y l l s i n B a c t e r i a l

The

p h o t o s y n t h e t i c apparatus

Rhodopseumonas v i r i d i s ,

o f p u r p l e b a c t e r i a , e. g. o f

contains the s o - c a l l e d " s p e c i a l p a i r " of

b a c t e r i o c h l o r o p h y l l - b molecules, contiguous

Photosynthesis

(BChl-b) » which c o n s i s t s o f 2

t e t r a p y r r o l e d i s k s overlapping a t the r i n g s I of the

b a c t e r i o c h l o r o p h y l l b m o i e t i e s which l i e about 300 pm a p a r t from each o t h e r ( 1 8 ) . The p h o t o i o n i z a t i o n o f t h e s p e c i a l p a i r a c c o r d i n g Equation

1 i s thought t o be t h e o r i g i n o f t h e charge s e p a r a t i o n

d r i v i n g the e l e c t r o n flow i n b a c t e r i a l photosynthesis

(BChl-b)

2

+

hv

y

(BChl-b)

+ 2

+

e"

(18, 1 9 ) .

(1)

A s i m i l a r NIR band o c c u r s a t about 1300 nm i n t h e o x i d i z e d form o f the s p e c i a l p a i r ,

+

( B C h l - b ) , which can be generated 2

e i t h e r by

i l l u m i n a t i o n or chemical o x i d a t i o n (19). The

s i m i l a r i t i e s i n NIR a b s o r p t i o n between t h e s e r i e s o f

l a n t h a n o i d doubledeckers

and t h e o x i d i z e d s p e c i a l p a i r s

suggested

e x p e r i m e n t s which might produce o x i d i z e d c a t i o n i c s p e c i e s from t h e neutral Ce(P)

2

sandwiches. Thus i t would be p o s s i b l e t o prove t h e

i d e a t h a t these NIR bands were t y p i c a l f o r whatever k i n d o f o x i d i z e d IV p a i r o f p o r p h y r i n r i n g s . Indeed, o x i d a t i o n o f t h e Ce sandwiches


102


a c c o r d i n g E q u a t i o n 2 produces Λ-cation r a d i c a l s a l t s +

Ce(0EP)

like

S b C l " ( 1 , 2 0 ) , which a l s o show a NIR-CTI band, as does

2

6

P r ( T T P ) , the o x i d a t i o n p r o d u c t o f P r H ( T T P ) . I n f a c t , t h e s e s p e c i e s 2

2

may have more than one NIR band; the s p e c t r a of the n e u t r a l sandwiches a l s o show s h o u l d e r s a t t h e low energy t a i l s of the main NIR band (see F i g u r e 2 ) . Examples and o p t i c a l s p e c t r a a r e shown i n T a b l e I I , The s p e c i e s have been c h a r a c t e r i z e d by e l e m e n t a l a n a l y s e s , c o n d u c t i v i t y measurements, c y c l i c voltammetry, IR-, and NMR


Ce(P)

>

2

Ce(P)

+ 2

+

e"

spectra,

(2)

The NIR a b s o r p t i o n s between 1100 and 1500 nm t h e r e f o r e a r e a common p r o p e r t y of two c l o s e l y a s s o c i a t e d p o r p h y r i n or h y d r o p o r p h y r i n r i n g s one o f which i s o x i d i z e d t o a r a d i c a l . E s p e c i a l l y noteworthy i s the p a r a l l e l i s m between the redox p a i r s d e f i n e d i n E q u a t i o n s 1 and 2 which i s p r e s e n t l y f u r t h e r i n v e s t i g a t e d i n our l a b o r a t o r i e s ( 1^).

Table I I .

E l e c t r o n i c A b s o r p t i o n S p e c t r a o f A) Cerium B i s p o r p h y r i n a t e S a l t s ( 1 ) , B) Praseodymium B i s ( t e t r a - p - t o l y l p o r p h y r i n a t e ) Sandwich S p e c i e s (14) i n nm,

log £

i n brackets, Hewlett-Packard

s p e c t r o p h o t o m e t e r 8451 A; NIR: Z e i s s DMR

photometer

21)

Compound

NIR band

UV/VIS bands

A) S a l t Ce(0EP) Ce(TPP) Ce(TTP)

+ 2

1270(3.50)

515(3.87),

354(4.94)

SbCl "

1350(3.93)

662(3.53),

384(5.04)

PF ~

1350(3.42)

542(4.08),

396(5.27)

6

+ 2

6

+ 2

a

SbCl "

6

B) Complex PrH(TTP) Pr(TTP)

2

2

(8) (20)

556(4.03), 510(3.94), 1140(3.57)

b

672(3.69),

413(5.60)

412(4.95)

a) Other bands: 1762(3.14), 808(4.50).b) Other band:

1450(3.36).-


6.

B U C H L E R ET A L .


103

Acknowledgments

Financial

support

of the Deutsche

Forschungsgemeinschaft,

t h e Fonds

der Chemischen I n d u s t r i e , and t h e V e r e i n i g u n g von Freunden d e r Technischen Hochschule Darmstadt i s g r a t e f u l l y acknowledged. The authors

thank P r o f e s s o r s

(Seattle) Fischer

A . Vogler

for illuminating (Strasbourg)

structure

(Regensburg)

discussions,

for the excellent

determinations,

and M . Gouterman

Professors cooperation

and a r e v i e w e r

R. Weiss and J . on t h e c r y s t a l

for a useful

comment.


Literature Cited 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17.

Buchler, J. W., Elsässer, Κ., Kihn-Botulinski, M., Scharbert, B. Angew. Chem. 1986, in press. Number 41 in the series Metal Complexes with Tetrapyrrole Ligands. Buchler, J. W., Kihn-Botulinski (formerly Knoff), M. In "Optical Properties and Structure of Tetrapyrroles", G. Blauer, H. Sund, Eds., de Gruyter, Berlin (1985), pp. 91-105. Buchler, J. W., De Cian, Α., Fischer, J., Kihn-Botulinski, Μ., Paulus, H., Weiss, R. J. Am. Chem. Soc. 1986, in press. Kihn-Botulinski, M. Doctoral Dissertation, Technische Hochschule Darmstadt, 1986. Buchler, J. W. In "Porphyrins and Metalloporphyrins", Smith, K. M., Ed.; Elsevier: Amsterdam, 1975; pp. 157-231. Buchler, J. W. In "The Porphyrins", Dolphin, D., Ed.; Academic: New York, 1978; Vol. I, pp.389-483. Gouterman, M. In "The Porphyrins", D. Dolphin, Ed.; Academic: New York 1978; Vol. III, pp. 1-165. Buchler, J. W., Kapellmann, H.-G., Kihn-Botulinski (formerly Knoff), M., Lay, K. L., Pfeifer, S. Z. Naturforsch. 1983, 38b, 1339-1345. Holten, D., and Gouterman, Μ., personal communication (see also contribution to this volume). Fuhrhop, J. H., Wasser, P., Riesner, D., Mauzerall, D. J. Am. Chem. Soc. 1972, 94, 7996-8001. Chang, A. T., Marchon, J. C. Inorg. Chim. Acta 1981, 53, L 241-L243. De Cian, Α., Moussavi, Μ., Fischer, J., Weiss, R. Inorg. Chem. 1985, 24, 3162-3167. Shimomura, E. T., Philippi, Μ. Α., Goff, H. M., Scholz, W. F., Reed, C. A. J. Am. Chem. Soc. 1981, 103, 6778-6780. Tansil, S. Diplomarbeit, Technische Hochschule Darmstadt, 1985. Briegleb, G. "Elektronen-Donator-Acceptor-Komplexe". Springer: Berlin 1961. Shannon, R. D., Prewitt, C. T. Acta Crystallogr. 1969, B25, 925-929. Lever, A. B. P. "Inorganic Electronic Spectroscopy" (second edition). Elsevier: Amsterdam 1984, pp. 647-658.


104

18. 19. 20.


Deisenhofer, J., Epp, O., Miki, K., Huber, R., Michel, H. J. Mol. Biol. 1984, 180, 385-398. Davis, M. S., Forman, Α., Hanson, L. K., Thornber, J. P., Fajer, J. J. Phys. Chem. 1979, 83, 3325-3332. Elsässer, K. Diplomarbeit, Technische Hochschule Darmstadt, 1985.


RECEIVED April 3, 1986


Optical Detection of the Lanthanoid Ion Contraction by Internal Charge

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