Spectrochemical studies on the ethylthiourea complexes of palladium (II) and platinum (II): M2(Etu)2X4(X = Cl, Br, I) and M(Etu)4A2(A = Cl, Br, I, ClO4, BF4, CF3COO).

PergamonPress, 1976. Printed in NorthernIreland

Spectrochlmica Acts, vol. 32A, pp. 291 to 294.

Spectrochemical studies on the ethylthiourea complexes of palladium (II.) and platinum (II) : M,(Etu) ,X4( X = Cl, Br, I) and M( Etu) aA,( A = Cl, Br, I, CIO,, BF,, CF,COO> . GIUSEPPE MARCOTRIQIANO, RAFFAELE BAYCISTUZZI and Istituto di Chimica Generale e Inorganiaa, University

GIOR~IO

PEYRONEL

of Modena, 41100 Modena, Italy.

(Received 31 December 1974) Abstract-The ethylthiourea complexes of Pd(I1) and PO(H): M,(Etu)sX, (X = Cl, Br, I) and M(Etu),A, (A = Cl, Br, I, C104, BF,, CF,COO) have been studied by i.r. and eleotronio speotre and the halide-bridged iWn(Etu).,X, oomplexes by bridge-splitting reaotions with nitrogen ligands. Ethylthiouree is S-ooordinated to the metal. Far i.r. spectra show v(MS) bands at 270-300 om-’ and, for the MI(Etu)& complexes v(&fX) bands oorresponding to terminal and bridging MX bonds. From the electronio speatra of the Pd(Etu),& (A = ClO,, BF,) oomplexes the Ar ( = 22120 cm-i) spectral parameter was obtained.

ligand

INTRODUCTIOR Few

metal

complexes

are knovvn, for

which

described

and

of N-substituted

particularly

only

two

nickel

[ 11. In previous

(II)

complexes

(II)

(II)

and

platinum

M(Etu)X,

(X

= Cl,

(A

I,

with

Br,

ClO,,

their

complexes

(II)

= Cl,

Br,

of zinc (II),

studying

[2] and some ethylthiourea (II)

and

conductometrio to

BF,,

investigate toward their

the

these i.r.

donor

metals

and

complexes,

their

also performed

of palladium

CFsCOO)

studying

and high frequency methods

[33.

properties we

have

of

now

spectra.

bridge-splitting

with nitrogen

In

and

the

to

ligand

investigated For

the

reactions

1: 1 were

donors.

Even

if

1:2,

high-frequency

indicate

1:4 complexes

aqueous plexes and

solution

for Pd(I1)

in DMF the 1:

(3345,

the coordination;

with

conductometric = 1: 1,

some

in acid

increases cm-l),

is well

atom

basis

of

that

molar

are non-electrolytes (Table

[3].

1) show that the v(NH)

influenced this may

of the ligand

in the indicate

are

complexes

by

[4] that

the

NH,

an

increased

the

thio-carbonyl lowered

when [5].

analysis

i.r.

of thiourea

of

the

[6] and N,N’-dimethylthiourea

to the band of N-ethylthiourea

the main contribution

In the complexes the new

bands

at

of v(CS) stretching

this band is split and one are shifted and

to lower

fre-

660-730 cm-r)

in

double bond character

from a sulphur coordina-

tion of the ligand to the metal. In the far i.r. spectra

conductivities are ionic and

and

on coordina-

coordinate

of the CS bond resulting

1 :l been

Y(CS)

in coordination

in dimethylformamide,

only

at

stretch-

is involved

with a decreased

have

the

is markedly

agreement

metals

also

a shoulder

indicating

established

frequency

the sulphur

of

of

In good

of the CN bond.

and of 1: 1, 1: 2, 1: 3, 1: 4 comboth

with

in energy

(720-750 cm-l

for

to iodo-

coordination

contributions

(l),

stretching

[2].

the chloro-

1542 cm-l,

bond character

or both

(1620-

the magnitude

to the metal.

a sulphur

(1670-1598

the

thiourea-com-

assigned mainly to v(NCN)asym

deformation

738 cm-l

and Pt(I1)

3250, 3165 cm-l)

significantly

1560 cm-l,

to

ligand

the electronegativity

bonded

at

the

frequencies

from

quencies

in the solid state;

1 complexes

with

band

[7] we assigned

of M:Etu

show that the 1: 4 complexes

The i.r. spectra bands not

for Pd(I1)

1: 4 complexes

obtained

and

the formation

higher

decreases atom

agreement

On

to

on decreasing

the halogen

It

of

In the 1: 1 complexes

derivatives

double

band

is, as in the analogous

of this shift

tion

than nitrogen-bonded

6(NH,)

shifted

1650 cm-l).

ing

rather

The

(1618 cm-l) plexes,

spectra

RESULTS AND DISCUSSIOhl

titrations

is sulphur

metal.

ligand

M(Etu),A,

stereochemistry

electronic

some

cadmium

i.r. spectra

and

titration

elucidate

were

stoichiometries

I)

them by radiochromatographic order

complexes

works we have prepared

some ethylthiourea and mercury

thioureas

of N-ethylthiourea

the

(Table

2) one or two new

bands in the region

of 300-270 cm-l

to v(MS) frequencies

in agreement

found for other similar complexes the

v(MS)

ethylthiourea on account 291

frequencies

are

[S, 91. However

higher

than for the thiourea of the greater

electron

are assigned

with the values the

N-

complexes

for

[S]

donating

proper-

292

R. BATTISTUZZI and G. PEYEONEL

G. ~COTRIOIANO,

Table 1. Principal ix. bands (cm-*) of ethylthiourea Assignments

‘J( NCXJ) asym+v(CS)+vibr.

WH2)+@i’?)

M

I’d

Etu

Pt

Pd.

1618VS ‘1633~s

X2!Etu)2C14

1,12(Et$Brb

(Etu) and its complexes

in the solid state

(h-2)

V(CS) tv(Cii)

Pt

Pa.

1648~s

1585vs,156Qm

Pf 738s

1560sh,1542vs 1594vs,1563w

732s,71,5s’

723sh,?‘iO:n

1631~s 1640~s 1580vs,1560sh1588vs,1562m 754w,705s 754mw,69is lG33VS

M2(E~u),14 U(Etu)&

1592vs,1562Sh

750m ,wk:

1638~s 1632~s 1588vs,1560sh159OvS,1563vs 738s,657s 749s ,720.?

M(Etu)4Br2

1628~ 1638~s 1580vs,1560sh1598vs,1562s 740~,6821~ 747~S,72w

I(Etu)412

:623vs 1625~s 1570vs,1560sh157Ovs,1562vs 74Os,678s 7j&ns,68:mS

MIEtu)4(C104)2

7620~s 1630~s 157Ovs,1562vs157Ovs,1561vs 743s,697s 742~11 ,665m

X(Etu)4(BF4)2

2575vs,156OVS

1634~s

N(Etu) 4(CF3COO)2 1638VS 162OVs

Table 2. Far ix. spectra (400-60 cm-l) Compound

v(W 345s

Pd2(Etu)2C14 Pd(Bu)

of solid Pd(II)-

u(fiW,

v (MS)

32Ovs, 275s

,292s

t

4c’i2

260mb

W2(Etu) Br 2 4 Pd(Etu) Br 4 2

743m , 6: ?:cs

1572vs,1560sh1580vS.,1562Sh72Os,69Os 742sh) c137?T ,__,_,_l

213vs,188m

and Pt(II)-ethylthiourea 6(kSC)

complexes

Other bands

‘ 170ms

141s,13Ew

28Ow

l8Ons

33%) 155311,1&5vs,

303m ,290ms

156m

34Ow,lO$-vs

291w ,279w

172ms

332~,1:5s~l,lrc~~~1~,12~.~~.85m .,I

nif Etu) 412

.328m,15Cw,12&

292m

175mb

Dd(Etu)4(C104)2

-

286s

179s

323~,15Cn,120sb

Pd(Etu)4!CF3COO)2

-

288sh,175sbr

1779

335m,i50,~,:24s

?t2(Etu)2C14

324~s

316vs,27Oms 299ms,284sh 30 5m ,284m

Pt(Etu)4C12 218vs

Pt2(Etd2Br4

Pt(Etu)4Br 2 Pt2(Etu) I 24 Pt(Etu)412

i7gvs

.-

Pt(i'tu)4(BF$2

-

ties of the ethyl group. N-ethylthiourea

accord The

the

frequency

thiourea

three

theregion

to MSC bending

vibrational

M,(Etu),X,

(M

are

and 180-140 cm-l

mass-dependent

frequencies. terminal

Ye

The

and

highest

for

Pt(I1))

for

the

complexes

260-190 cm-1

for iodo-derivatives

value

156s ,.148s j3Ob,2~24m,178s

metal-halide

to

the

other

two

to a to

vibrations

for Pd(I1)

than those for the Pt(I1) agreement found

with

for

toluidine, ligands

the

complexes. 1: 1

thiourea

for which structure

complexes

good values

.LY&,X4

a trans-disubstituted

has been found, suggests

for these complexes.

in the binuclear

was performed

Their

v(HX),

PR,, AsR,, py, pand other similar monodentate

A full characterization structure

and

The

are higher

L = PC&,

[lo-12]),

halogen-bridged

v(MX),,.

complexes

v(MX),

analogous Pt;

a similar structure

v(~MX)

corresponds

bridged

Y(MX) vibrations

(M =Pd,

assignabIe

vibration;

in close

reported

in the range 350-270 cm-lforchloro-, for bromo-

160sh,l50m j4Oc,255m,130vs

or medium

recorded

and

,::Om j4Os,228m,l35s,iO6s

290m

[S].

modes

= Pd(I1)

l58m ,150m jj~s,122Sb,90m

l60~!1,152mjjCm,25Sa,130vs

of 170-140 cm-r

values

complexes

163s ,148m 342m,98s

1:&I1

2ajm

vibrations

33i%h,140ms,l00m 338ms, 140sb

290m ,282sh

In the far i.r. spectra of the the medium

174es 182s

160~ ,i:lm 373m,324m,82s

278sh,267s

complexes

observedin

with

analogous

284m

17?vs,l4Oms

-

Pt(Etu)4(CF3COO)2

are assignable

297m ,282m 293m ,281~

?t(E?~u)~(Cio~)~

strongbands

195sh,163s

i’3:o-c

of this halogen-bridged H,(Etu),X,,

by bridge-splitting

complexes

reactions

with

Spectrochemical studieson the ethylthiourea complexesof palladium(II) and platinum (II) N-donor ligands, which cannot split sulphurbridges [13], in dimethylformamide (DMF) or methylcellosolve (MCS) : Pd,(Etu),X_, + Zp-to1DMF, Pd(Etu),Xs + tram+Pd(p-tol),Xs

(1)

+ SPY DMF+EtoH*Pd(Etu),X,

Pd,(Etu),X,

+ trans.-Pd(py)sXs Pd,(Etu)sX,

(2)

+ en DMF, Pd(Etu),Xs + cis-Pd(en)X,

Pd,(Etu),X,

(3)

+ 4en DMB, 2Etu + Pd(en),Xs

Pt,(Etu),X,

+ bipy *

(4)

Pt(Etu),X, + cis-Pt(bipy)X,

(6)

(p-to1 = p-toluidine, py = pyridine, en = ethylenediamine, bipy = 2,2’-dipyridine). The Pd(I1) and Pt(I1) complexes with N-donors formed in the reactions (l-5) were isolated and characterizedby elemental analysis and i.r. and far i.r. spectra. The r(PcW) and p(PdX) values for the complexes (l-3) and v(PdN) for the complex (4) are in good agreement with those reported in a previous work [12]. The Y(PtX) and v(PtN) found for complex (5) well agree with literaturedata [ 141. The bridge-splitting products of mono-dentate ligand reactions (1, 2) and bi-dentate ligand reactions (3-6) indicate that the mechanism of the

halogen-bridge cleavage in the P$(Etu)sX, and Pt,(Etu),X, complexes are similar to those described for Pd,(Tu),X, [ 121. The i.r. bands of the perchlorate and fluoborate anions show (Table 3) a splitting of the us mode in three not very well defined peaks or shoulders, a medium intensity for the vi band and the absence of the us band, indicating that these anion groups may be weakly coordinatedlike in some copper(I1) complexes [15, 161. For the trifluoroacetate derivatives the frequency is higher (1680 cm-l for the y(COO),,, Pd(II)- and 1686 cm-1 for the Pt(II)-complex) than in the CFsCOOK salt (1660 cm-r), while the band assignable to the v(COO),~, mode is masked by the very strong band of ethylthiourea at 1440 cm-l. The electronic spectra of the solid 1: 1 and 1: 4 Pd(II)- and Pt(II)-ethylthiourea complexes are reported in Table 4. Only the first band of the 1: 1 complexes may be assigned to a d-d transition; its values are in good agreement with the spectrochemical order of the metal ions Pt(I1) > Pd(I1) and of the halide ions Cl > Br > I and very close to the values of the corresponding complexes of t,hiourea,indicating that the presence of an ethyl group in the ligand does not appreciably effect the complexation. The d-d bands in the Pd(Etu)&, (A = ClO,, BF,) complexes are in good agreement with the values of other PdS, chromophores[ 171and may be assigned to the ‘A,, -+ 1J&7(z2 - y2 + zy) transi-

Table 3. The band of CIO1- and BF,- anions presentin the M(Etu),A, oomplexes (cm-l)

v1

3

Pd(Etu)4(C104)2

928m

-

1110‘Is,1182vs,1120sh

619s

Pt(Etu)4(C104)2

930m

-

1055vs,1070~s;1055sh

627s (610sh)

Pt(Etu)4(BF4)2

766m

358m

1115s,1055vs,1035sh

524ms

v3

v4

Table 4. Electronio spectra of solid Pd(II)- and Pt(II)-ethylthiourea Pd2 (2t.u) 2c14

21050

Pb(Etu)4C12 Pd2!Etu)2Brq P~(E~u)~B~~

lg8o&h

complexes (cm-l)

24390sh 28820

Pt2(Etu)2CJ:4

24150

Pt(Etu)4C12

23810sh 26880

Pt2(Etu)2Br4

23870

Pt(Etu)4W2

24390~11

W,(Etu),I4

l,g230~:12326CSil 28170sh

23529

2681Osh

26670ah 21413sh 25510sh

Pt(Etu)412

25510sh.

Pd!Etu)4(C104)2

20120sh 23250sh.28.250

Pt(Etu)&C104)2

2632Osh

PS(Etu)4(BP,)2

20000sh 22410sh 27780.

Pt(Etu)4(BF4)2

26:ZOeh

Pt(Etu)4(CF3COO)2

25?50$h 2557:

I'cl(Etu)412

P<(Etu)

(CF COO) 43 2

23250sh

2247&h

25060.

293

294

R. BATTISTUZZI and G. PEYRONEL

G. MARCOTRIaIANO, The

tion.

orbital

assuming

35F,

thiourea

in

parameter

the

(18),

places

spectroohemical

sulphur donors for Pd(I1) as follows:

A1, calculated

= 2100 cm-l

series

of

planar complexes

maleonitriledithiolate(

acetylacetonate(20200)

<

by

ethylthe

[19-211

17800) <

dithio-

ethylthiourea(22120)

diethyldithiocarbamate(24300)

<

<

dithiooxalate-

(28100).

spectra were in KBr

complexes nujol

Perkin-Elmer

disks

FIS3

(400-60 cm-l)

on the

with a Shimadzu The

solid

by

adding

Pd,(Etu),X4 pyridine

in 0.5 ml DMF DMF

complexes

(3),

(4).

adding = Cl,

cellosolve,

to Br,

(l-4) of

per-

of the

a solution

(l),

2 mM of

of ethylenediamine

cooling

at

0%

of

the

in

6 ml

crystallize.

Pt,(Etu)eX, of

methyl-

of 1 mM of 2,2’-bipyridyl

By cooling The

complexes

in

Pd(I1)

(5) was performed

solution

a solution

the

crystallize.

reaction

complexes

the ethylthiourea

paper

were

1 mM

in 6-7 ml DMF

4 mM

By

a I)

on filter

spectrophotometer.

of these N-ligands

1 ml of MeOH. Pt(bipy)X,

complexes

were

(2), 1 mM of ethylenediamine

The bridge-splitting (X

a

spectra

in 1 ml DMF

in 1 ml EtOH

in

and in nujol

reactions

complexes

or with

in

at, 0°C the complexes solutions have

containing

a deep-orange

colour. Acknowledgement-This

[6] [7]

with an Hitachi

to a solution

of 2 mM of p-toluidine

BAILEY andT.R. PETERSON,C~~.J.C%~. 46, 3119 (1968). [2] G. MARCOTRIGIANO, G. PEYRONEL and R. BATTISTUZZI,J. Inorg. Nucl. Chem., 37, 1675 (1975). [3] G. PEYRONEL, R. BATTISTUZZI and G. MARCOTRIOIANO, J. Chromatogr. 92, 419 (1974). [4] R. B. PENLAND, S. MIZUSHI~U, C. CURRAN and J. V. QUAQLIANO, J. Am. Chem. Sot. 79, 1575

solid

cm-l)

Electronic

MPS-5OL

bridge-splitting

formed

by

(4000-250

the

(600-250 cm-l)

spectrophotometer.

recorded

on

521 spectrophotometer

mulls on polythene

1 ml

recorded

mulls on polythene

R.

A.

(1957). [5] A. YAIKA~UCHI, R. B. PENLAND,

EXPERIMENTAL Infrared

REFERENCES [l]

work has been supported by a

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delle Richerche

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