Cyclic voltammetric and electrocrystallization studies of axially substituted biscyanophthalocyaninato metal complexes and related compounds

Synthetic Metals, 36 (1990) 387 - 397

387

CYCLIC V O L T A M M E T R I C AND E L E C T R O C R Y S T A L L I Z A T I O N STUDIES OF AX I A L L Y SU B ST I T U T E D BISCYANOPHTHALOCYANINATO METAL COMPLEXES AND R E L A T E D COMPOUNDS R. BEHNISCH and M. HANACK*

lnstitut fiir Organische Chemie, Lehrstuhl fiir Organische Chemie H der Universitiit Tiibingen, A u f der MorgensteUe 18, D~7400 Tiibingen (F.R.G.)

(Accepted February 20, 1990)

Abstract Cyclic voltammetric studies of several b i s c y a n o p h t h a l o c y a n i n a t o metal complexes and related c o m p o u n d s A[Mc(--2)M(+III)(CN)2 ] (A = Na, K, Bu4N; Mc = macrocycle = p h t h a l o c y a n i n a t o , t e t r a b e n z o p o r p h y r i n a t o , 2,3n a p h t h a l o c y a n i n a t o ; M = Co, Rh, Fe, Ru, Cr, Mn) in acetone/0.1 M Bu4NClO4 indicated t h a t t he first o x i d a t i o n process occurs on the macrocycle leading to an Mc(--1)M(+III)(CN)2 radical-cation species. By galvanostatic and pot e nt i os t at i c electrocrystallization of t he m o n o m e r i c c o m p o u n d s A[Mc(--2)M(+III)X2] in acetone, t he corresponding Mc(--1)M(+III)X2 c o m p o u n d s could be synthesized. These c o m p o u n d s were characterized by IR, far-IR and UV--Vis spectroscopy, as well as elemental analyses and mass s p ectr om et r y. In contrast to previous results, penta-coordinated c o m p o u n d s Mc(--2)M(+III)X were not observed in the electrocrystallization experiments.

Introduction** Metal phthalocyanines with trivalent metals containing t w o axial cyano or t h i o c y a n a t o groups, such as Na[PcCo(CN)2], K[PcRh(CN)~] or K[PcCo(CNS)2] are i m p o r t a n t precursors (monomers} in t he preparation o f bridged c o m p o u n d s such as [PcCoCN]n [1], [ P c R h C N ] , [2] and [PcCoSCN], [3]. R ecen t reports on electrochemical oxi dat i on of K[PcCo(CN)2 ] in acetonitrile to give a highly conductive c o m p o u n d 'PcCoCN' [4] which is

*Author to whom correspondence should be addressed. **Abbreviations: Mc = macrocycle, Pc = phthaiocyaninato, 2,3-Nc -- 2,3-naphthalocyaninato, TBP = tetrabenzoporphyrinato, CV = cyclic voltammetry, Bu~NClO4= tetrabutylammonium perchlorate, SCE -- saturated calomel electrode, Ezl 2 = half-wave potential, E p a = anodic peak potential, Epc -- cathodic peak potential, v = scan rate, ~ E p -d i f f e r e n c e between Epa and Epc. 0379-6779/90/$3.50

© Elsevier Sequoia/Printed in The Netherlands

388 different from our first reported [PcCoCN]n [1] led us to investigate the electrochemical behavior of monomeric compounds A[McMX:] (with A = Na, K, BuaN; Mc = Pc, TBP [5], 2,3-Nc [6]; M = Co, Rh, Fe [7], Ru, Cr, Mn [8]; and X = CN, SCN) by cyclic voltammetric measurements in acetone. The cyclic voltammetric behavior of A[Pc(--2)Fe(+III)(CN):] with various cations (A) in CH~CI:/BuaNCIOa has been reported earlier [9]. In comparison to the redox potentials of PcFe [10], two quasi-reversible halfwave potentials concerning the metal oxidation Fe(+II)/Fe(+III) and the ring oxidation at 0.07 and 0.77 V, respectively (versus Ag/AgC1; LiC1/EtOH) were found. Recently, CV measurements of K[Pc(--2)Co(+III)(CN)2] and related compounds in acetonitrile were presented [4, 11]. Because of the absence of a supporting electrolyte, however, the potential differences between the anodic and the cathodic peak potentials (Epa --Ep¢) are in the range of 200 800 mV. This fact prompted the authors to ignore the cathodic peak potential Ep¢, which always led to larger oxidation potentials [11]. Therefore, these results must be regarded as an estimate of the real half-wave potential. The following cyclic voltammetric investigations at lower scan rate led to the proposition of a new mechanism for the potentiostatic electrocrystallization. Furthermore, we present here more detailed spectroscopic studies (IR, UV-Vis, far-IR) concerning the products of galvanostatic and potentiostatic electrocrystallization of the monomers Na[PcCo(CN):], BuaN[PcCo(NCS):] and K[PcRh(CN)2] in acetone. For the first time, these experimental results clearly demonstrate oxidation of the macrocycle, which is in accordance with recently reported structures of crystals obtained by electrochemical oxidation of K[PcCo(CN)2] [12].

Experimental Cyclovoltammetric measurements were performed on a PAR 273 potentiostat/galvanostat (EG & G) interfaced with an IBM PC/XT-type microcomputer data station. A standard three-electrode cell configuration was employed using a Pt disk working electrode (Metrohm), a Pt wire auxiliary electrode and a silver wire as a Ag/Ag ÷ quasi-reference electrode. Ferrocene was used as an internal reference redox system. Acetone was distilled twice over P2Os and transferred via a vacuum line directly into the deoxygenated cell. After addition of a 0.1 M amount of recrystallized BuaNC10 a as supporting electrolyte, the electrochemically available potential range was checked prior to use. The macrocyclic c o m p o u n d s were added under nitrogen to give a saturated solution. The redox potential of the ferrocene/ ferricenium couple in acetone was measured to be 0.52 V {versus SCE). The reported midpoint potentials {versus SCE) are accurate to +20 mV. Galvanostatic electrocrystallization experiments using a simple twoelectrode cell configuration with two Pt plate electrodes were performed on

389 a current source (Keithley 225) without any supporting electrolyte. Potentiostatic electrocrystallization experiments were performed on a W e n k i n g LB 8 1 H (Bank) a n d a 1 0 0 1 T-NC (Jaissle) p o t e n t i o s t a t . A s t a n d a r d t h r e e - e l e c t r o d e c o n f i g u r a t i o n was used w i t h a spherical Pt w o r k i n g e l e c t r o d e ( S c h o t t ) , a Pt w i r e c o u n t e r e l e c t r o d e a n d a Ag/AgC1 r e f e r e n c e e l e c t r o d e {saturated LiC1 in C2HsOH). T h e r e f e r e n c e e l e c t r o d e was c o n n e c t e d b y a salt bridge c o n t a i n i n g Bu4NC1Oa/acetone o v e r a Luggin capillary t o t h e electroc h e m i c a l cell. I n f r a r e d s p e c t r a w e r e r e c o r d e d o n B r u k e r I F S 48 and P e r k i n - E l m e r 398 i n s t r u m e n t s as K B r pellets. F a r - i n f r a r e d s p e c t r a w e r e o b t a i n e d o n a B r u k e r I F S 1 1 4 c i n s t r u m e n t in p o l y e t h y l e n e . U V - V i s s p e c t r a w e r e t a k e n o n a P e r k i n - E l m e r L a m b d a 5 s p e c t r o m e t e r in c h l o r o f o r m solutions.

Results a n d discussion Cyclic voltammetry We p r e s e n t h e r e c o m p a r a t i v e cyclic v o l t a m m e t r i c studies o f a series o f A[Mc(--2)M(+III)(CN)2 ] and A:[Pc(--2)M(+II)(CN)2 ] complexes in a c e t o n e w i t h a d d i t i o n o f 0.1 M BuaNC10 a as s u p p o r t i n g e l e c t r o l y t e . In a c c o r d a n c e w i t h o t h e r results [ 9 ] , v a r i a t i o n o f t h e c a t i o n N a ÷, K ÷ a n d Bua N+ has insignificant i n f l u e n c e w i t h i n t h e a c c u r a c y ( + 0 . 0 2 V) o f t h e r e p o r t e d h a l f - w a v e p o t e n t i a l s o n t h e o x i d a t i o n p r o c e s s E1/21 {Table 1). In general, f o r t h e h a l f - w a v e p o t e n t i a l E1/21 ( T a b l e 2), t h r e e d i f f e r e n t assignm e n t s s e e m t o b e possible:

(i) o x i d a t i o n o f t h e c o b a l t ion

[Pc(--2)Co(+III)X2]-

>

Pc(--2)Co(+IV)X2 + e -

TABLE 1 Half-wave potentials of A[PcCoX2] under variation of the cation A or the axial ligand X in acetone/0.1 M BuaNCIO4 IV vs. SCE] Compound

Ell21

Na[PcCo(CN)2 ] K[PcCo(CN)2 ]

0.92 b 0.88 b

BuaN [PcCo(SCN)2 ]

0.88 b

K[PcCo(NCS)2]

0.84 b

Assignment

Pc(--2 )[ Pc(--1)

EI/2 2

--0.34 a --0.32 a

EI/2 3

El/2 4

El~21 -- EI/2 4

--0.83 c --0.91 c

--1.46 b --1.54 b

2.38 2.42

--1.02 a --0.95 a

--1.52 b --1.495

2.40 2.33

Pc(--3 )/ Pc(--2)

aQuasi-reversible electron transfer (AEp = 80 - 100 mV; ipa/ipc ~ 1). bReversible electron transfer (AEp = 60 - 70 mV; ipa/ipc ~ 1). CTwo-electron reduction and/or chemical reaction.

390 TABLE 2 Half-wave p o t e n t i a l s o f A [ M c C o ( C N ) 2 ] u n d e r v a r i a t i o n o f t h e m a c r o c y c l i c s y s t e m in a c e t o n e / 0 . 1 M Bu4NCIO4 I V vs. SCE] Compound

El/21

El/2 2

El/2 3

Na[PcCo(CN)2 ] Na[(H3C)sPcCo(CN)2 ] Na[(t-Bu)4PcCo(CN)2] Na[(O2N)4PcCo(CN)2 ] Bu4N[TBPCo(CN)2 ] K[2,3-NcCo(CN)2 ]

0.92 b 0.62 b 0.77 b 1.30 d 0.54 b 0.50 b

Assignment

Pc(--2)/

Pc(--3)/

Pc(--1)

Pc(--2)

--0.83 --0.94 --0.93 --0.48 --0.77 --0.41

E1/2 4 c c c c a a

--1.46 --1.52 --1.50 --1.13 --1.24 --0.92

b b b b a b

aQuasi-reversible e l e c t r o n t r a n s f e r (AEp = 80 - 100 m V ; ipa/ipc .~ 1). b R e v e r s i b l e e l e c t r o n t r a n s f e r (AEp = 60 - 70 m V ; ipa/ipc ~ 1). CTwo-electron r e d u c t i o n a n d / o r c h e m i c a l r e a c t i o n . d U n c e r t a i n value ( d u e t o s o l v e n t o x i d a t i o n ) .

(ii) oxidation of the axial ligand X 2[Pc(--2)Co(+III)X2]-

~ 2Pc(--2)Co(+III)X + X2 + 2 e -

(iii) oxidation of the macrocyclic ring system [Pc(--2)Co(+III)X2]-

> Pc(--1)Co(+III)X2 + e-

In previous CV studies on porphyrinatocobalt compounds, oxidation on the metal ion to form a [Pc(--2)Co(+ IV)] 2+ species was not regarded as a possible reaction path [13, 14]. Furthermore, the oxidation of free cyano groups was reported to be a broad irreversible process at about 1.2 V (versus SCE) [15]. Interestingly, in our investigations the half-wave potential E1/~ 1 changes with the variation of the macrocyclic ring system (Table 2). According to the data given in Table 2, electron-withdrawing substituents like nitro groups raise the E l n I to 1.30 V, whereas electron-donating substituents like methyl {0.62 V) or t-butyl groups (0.77 V) reduce the oxidation potential E1/21 {Table 2; Fig. 1). Furthermore, a change in the macrocyclic ring system to the more easy oxidizable TBPCo [ 1 6 - 18] or 2,3-NcCo complexes [17, 18] led to a lower oxidation potential E l n ' of 0.54 and 0.50 V {versus SCE) in the case o f Bu4N[TBPCo(CN)2] and K[2,3-NcCo(CN)2], respectively (Table 2). This dependence of E1/21 on the variation of the macrocycle clearly indicates that the oxidation process occurs on the macrocyclic ring. A further p r o o f for this assignment is shown in Table 3, where the macrocyclic ring (Pc) remains unchanged and the metal atom varies from Cr, Mn, Fe, Ru, Co to Rh. As expected, we did not observe any change of E,/2 ~

391 10.0

~z ~

e~ a.,.

5.0

0.0

t9

-5.0

Pc-Oxidation -,o.o

Lb'"b's'"b.b'"-'d.5"af0":i~'"-d0 POTENTIAL vs. SCE IV]

Fig. 1. Cyclic v o l t a m m o g r a m o f Na[(t-Bu)4PcCo(CN)2] at a scan rate of 100 m V / s in acetone. TABLE 3 Half-wave potentials of A[PcM(CN)2] under variation of the central ion in a c e t o n e / 0 . 1 M Bu4NCIO4 [V vs. SCE] Compound

El/l

E 1/2 2

E 1/2 3'

Na[PcCr(III)(CN)2 ] Na[PcMn(III)(CN)2 ] K2[PcFe(II)(CN)2] K2[PcRu(II)(CN)2 ] K[PcCo(III)(CN)2] K[PcRh(III)(CN)2]

0.90 a 0.89 a 0.93 a 0.93 a 0.885 0.905

--0.565 --0.14 b 0.145 0.345

--1.23 a --0.91 a --0.99 a --0.97 a --0.91 c --0.90 c

Assignment

Pc(--2)/ Pc(--1)

M(II)/ M(III)

M(I)/ M(II)

E 1/2 4

--1.34 a --1.52 a --1.545 --1.45 b Pc(--3)/ Pc(--2)

aQuasi-reversible e l e c t r o n transfer (AEp = 80 - 100 m V ; ipa/ipc ~- 1). bReversible e l e c t r o n transfer (AEp = 60 - 70 m V ; ipa/ipc ~, 1). CTwo-electron r e d u c t i o n and]or chemical reaction.

within the accuracy of the reported half-wave potentials (+0.02 V). For the c o m p o u n d s with a divalent metal ion, e.g. K2[Pc(--2)Fe(+II)(CN)2] and K:[Pc(--2)Ru(+II)(CN)2], another reversible oxidation process E1/22 at +0.14 and +0.34 V, respectively, was observed (Fig. 2). In accordance with the CV results on A[Pc(--2)Fe(+III)(CN)2 ] [9] and Bu4N[OEP(--2)Ru(III)(CN)2] [19], the half-wave potential Eli22 corresponds to the oxidation of the metal atom, e.g. Fe(+II)/Fe(+III) and Ru(+II)/Ru(+III), respectively. In the reductive area, a chemical reaction or a two-electron reduction step complicates the assignment of E1/2. In our opinion, the reduction of the anionic species [McM(CN)2 ]- may lead to abstraction of a cyanide group, but a two-electron reduction on the Co(+ III) central ion to a Co(+I) species also appears to be possible. Because of the constant potential difference

392 2.0

0.0 E-

z -2.C C9 --4.0

Pc-Oxidation

-6.o

~.b

. . . .

o.~ . . . . POTENTIAL vs. SCE [V]

o.b

Fig. 2. Cyclic voltammogram of K2[PcRu(CN)2] at a scan rate of 100 mV/s in acetone.

TABLE 4 CV data of different monomeric compounds at v ~< 50 mV/s in acetone/0.1 M BuaNCIO4

[V vs. SCE] Compound

Epa

Epc I

Epa -- Epc ]

K[PcCo(CN)2] Na[PcCo(CN)2] Na[(HaC)sPcCo(CN)2] BuaN[TBPCo(CN):] K[2,3-NcCo(CN):] K[PcCo(NCS)2]

0.92 0.96 0.63 0.53 0.48 0.90

0.64 0.68 0.28 0.23 0.21 0.68

0.28 0.28 0.35 0.30 0.27 0.22

Epa = anodic peak potential. Epc I = symmetrical cathodic peak potential (adsorption).

b e t w e e n E l / 2 ! and E1/24 (Table 1) and the dependence of the fourth halfwave potential on the macrocyclic system, we assign E1/24 to a macrocyclic reduction, e.g. [ec(--2)Co(+I)]-/[Pc(--3)Co(+I)] 2-. Nevertheless, further investigations on the reduction range are necessary to confirm these assignments. With cyclic voltammetric studies at slower scan rates (v ~< 50 mV/s), which are important to study the mechanism of the anodic electrocrystallization of the monomeric compound (Table 4), we observe some further potential waves. After the usual oxidation wave Epa of the macrocyclic system, two reductive waves at Eve and Ep¢l, respectively, were found. Whereas the difference between Epa and Evc I remains independent of the macrocycle at 0.22 - 0.35 V, the second reductive peak Epc] shows sharp symmetrical peak behavior (Fig. 3), which may be attributed to an adsorption process of an electrocrystallization product. Further cyclic voltammetric investigations concerning this adsorption phenomena, e.g. the simula-

393 0.2 -

Adsorption 0.0 -

~-0.2

~ -0.4

-0.6 Pc-0xidation -0,8

~:0

'

'

'

'

0.~5

POTENTIAL vs, s e e

. . . .

O:lO

[V]

Fig. 3. Cyclic voltarnmogram of Na[PcCo(CN)2] at a scan rate of 20 rnV]s in acetone.

tion of an adsorption process b y electrochemical methods [20], are in progress.

Electrocrystallization Although the anodic electrocrystallization of K[PcCo(CN)2 ] in CH3CN to a c o m p o u n d 'PcCoCN' has been described [4], the stoichiometrical similarity to our bridged c o m p o u n d [PcCoCN]n [1] prompted us to reproduce the electrocrystallization experiments under various conditions. Under galvanostatic conditions w i t h o u t any supporting electrolyte, a change o f the solvent (acetone instead of acetonitrile) or the counter-cation {sodium instead of potassium) led to a sample identical (IR spectrum, powder diffraction) to the sample reported [4]. Recently, the electrocrystallization in acetone has been published as a patent [4d]. Because of the addition of Bu4NC104 as supporting electrolyte in our potentiostatic experiments, the rate of crystal growth drastically decreased. For that reason, the supporting electrolyte of the saturated Ag/AgC1 reference electrode (LiC1 in ethanol) diffuses slowly into the electrolysis cell. Within a few days, the higher nucleophilicity of the chloride ions in comparison to perchlorate ions leads to an axial ligand exchange. Therefore, we observe in the potentiostatic electrocrystallization of Na[PcCo(CN)2 ] and K[PcCo(NCS)2 ] the chloride-containing c o m p o u n d s [Pc(--1)Co(+III)CI]CN and [Pc(--1)Co(+III)C1]SCN, respectively. These new c o m p o u n d s have been fully characterized b y elemental analyses, mass spectrometry, IR, U V - V i s and far-IR spectra [21]. The IR data of the galvanostatic and potentiostatic electrocrystallization products concerning the anodic electrolysis of Na[PcCo(CN)2], K[PcCo(NCS)2 ] and K[PcRh(CN)2 ] are summarized in Table 5. In comparison to the IR spectra of the monomeric and the bridged compounds, we found t w o new predominant bands at 1364 - 1367 and 1458 - 1460 cm -1, respectively, whereas the neighboring bands of the Pc(--2) species at 1 4 2 4 - 1428 and

394 TABLE 5 IR data of various Co(III) complexes (KBr, cm -l) Compound

C---N

[Pc(--2)CoCN] n Na[Pc(--2)Co(CN)2] [Pc(--2)CoSCN]n K[Pc(--2)Co(NCS)2] Pc(--1)Co(CN)2 a [Pc(--1)CoCI]CN b Pc(--1)Co(NCS)2 a [Pc(--1 )CoCI]SCN b

2155m 2126m 2110m 2095m 2134w 2079w 2098m 2085w

Pc(--1)CoCl2

CH out-of-plane

Reference 25 25 3c 3c

1516s 1518s 1518s 1517s 1458m 1458s 1458s 1459s

1425s 1424s 1428s 1426s 1366m 1367s 1364s 1366s

728s 734s 726s 732s 734s 738s 735s 737s

1456s

1367s

737s

aSynthesis by galvanostatic electrocrystallization. bSynthesis by potentiostatic electrocrystallization. s = Strong intensity; m = medium intensity; w = weak intensity.

1 5 1 6 - 1 5 1 8 c m -1 decrease (Fig. 4). T h e s e new bands at 1365 and 1460 cm -2 are diagnostic o f [ P c ( - - 1 ) C o ( + I I I ) ] 2+ radical-cation species [22 - 2 4 ] . Because o f this o x i d a t i v e d o p i n g process, t h e IR spectra o f t h e Pc(--1) species are o v e r l a p p e d b y e l e c t r o n i c transitions which leads to l o w e r intensities, especially in t h e range o f the CN valence f r e q u e n c y . Thus, we observe in c o m p a r i s o n t o t h e m o n o m e r i c c o m p o u n d s a large decrease in t h e intensity o f the c y a n o f r e q u e n c y and a slight shift f r o m 2 1 2 6 to 2 1 3 4 cm -1 in t h e a b s o r p t i o n energy. This shift m a y be e x p l a i n e d b y a c o m p l e x coupling of t h e o - d o n o r and ~r-acceptor abilities o f the Pc(--1) radical-cation system and the o - a c c e p t o r and 7r
395

I

I

g

g

2BB8

1808

18~0

(a)

laO~

12~8

I~

3~

WAVENUMBEES CM i

20~0

(b)

1800

1600

14-00

120fl

1000

800

600

WnVENUMBERS CM-I

Fig. 4. Infrared spectra (KBr pellets) of (a) [Pc(--I)Co(+III)CI]SCN and (b) Pe(--I)Co(+III)(SCN)2.

TABLE 6 UV-Vis data of various Co(III) complexes (in CHCla, nm) Compound

~-~(1 )

K[Pc(--2)Co(CN):] K[Pc(--2)Co(NCS)2]

Q

~'-~'(2 )

670 669

B

Reference

350 350

25 3c

Pc(--1)Co(CN)2 [Pc(--I )CoCl]CN Pc(--1)Co(NCS)2 [Pc(--1)CoCl]SCN

704 718 718 723

530 514 519 515

483 398 434 440

334 335 332 335

Pc(--1)CoC12 Pc(--1)CoBr2

722 727

516 511

437 476

335 335

24 24

However, the typical radical-cation bands decrease within a few days, w h e r e a s t h e t r a n s i t i o n s o f t h e P c ( - - 2 ) C o ( + I I I ) species at 350 and 6 6 9 - 6 7 0 n m , r e s p e c t i v e l y increase. T h i s r e d u c t i o n p r o c e s s s h o w s t h e instability o f t h e P c ( - - 1 ) C o ( + I I I ) X 2 c o m p o u n d s in s o l u t i o n . I n t e r e s t i n g l y , especially in t h e g a l v a n o s t a t i c e l e c t r o c r y s t a l l i z a t i o n p r o d u c t s P c C o ( C N ) : a n d PcCo-

396 I.O~

-

I -o

E 0.8.

0"8

0"6

0"6

0"4

0"4

0.2

0"2

0"O

300

.

.

.

.

.

.

-- .

~00

.

.

.

.

SO0

.

.

.

.

.

.

60o

.

.

.

.

.

.

700

O" 0

aOO Inmi

Fig. 5. UV-Vis spectrum (CHC]3) of Pc(--1 )Co(+III)(CN)~.

(SCN):, we observe some m o n o m e r i c bands in the IR as well as in the UV-Vis spectra. These results suggest t hat m o n o m e r i c units m ay be included in the crystal structure of the galvanostatic electrocrystallization products. Thus, these c o m p o u n d s should be assigned m ore correctly as

Pc(--1)Co(+III)X2 X A[Pc(--2)Co(+III)X2] [12]. Because of the low yields in the potentiostatic electrocrystallization experiments, we added an insulating material (KBr) for the powder conductivity measurements. Nevertheless, a 10% by weight amount of the electrocrystallization product together with 90% of KBr led to a conductivity of at ]east 10-4 S/cm.

Conclusions Th e CV studies of axially substituted b i s c y a n o p h t h a l o c y a n i n a t o metal complexes and related c o m p o u n d s A[McM(CN):] (with A = Na, K, BuaN; Mc = Pc, substituted Pc, TBP, 2,3-Nc; and M = Co, Rh, Fe, Ru, Cr, Mn) in acetone/0.1 M BuaNC104 showed that the first oxidation process occurs in the case o f trivalent central ions on the macrocycle, whereas complexes with divalent central ions are first oxidized on the metal ion. Galvanostatic and potentiostatic electrocrystallization of the m o n o m e r s Na[PcCo(CN)2], K[PcCo(SCN)2] and K[PcRh(CN}2] in acetone yielded Pc(-- 1)M(+ III)X2 radical-cation species. These c o m p o u n d s are characterized by bands in the IR spectra at 1364 - 1367 and 1458 - 1460 cm -1 and in the UV-Vis spectra (in CHCI3) at 335, 398 - 476, 510 - 530 and 704 - 727 nm, respectively.

397

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