Nickel(II) complexes of N,N′-dicyclohexyl- and N,N′-dibenzyl-dithiooxamide

INORG.

NUCL.

CHEM.

LETTERS

NICKEL(II)

Voh 8, pp. 299-303, 1972.

Pergamon

Press.

Printed

in

Great

Britain.

COMPLEXES OF N , N ' - D I C Y C L O H E X Y L - A N D

N~ N' -DIBENZYL-DITHIOOXAMIDE

G.C. Pellacani and G. Peyronel Istituto di Chimica Generale e Inorganica, Universit~ di Xodena Italy (Received 14 December 1971)

Dithiooxamide and N,N'-disubstituted

dithiooxamides in neu-

tral media generally give polymeric and insoluble (NIL) x complex es (1,2), while tetraethyldithiooxamide strong acid media dithiooxamide, xyethyl-dithiooxamide

does not react

(2). In

N,N'-dimethyl- and N,N'-dihydro

give S,N-coordinated low-spin complexes

NiL2X 2 (X=CI,Br,HS04,CI04)

(3), while tetramethyl- and tetra

ethyl-dithiooxamide give S,S-coordinated high-spin complexes NiL3(CI04) 2 (4). We investigated the nickel(II) N,N'-dicyclohexyl-

complexes of

(DCH2DH2) and dibenzyl-dithiooxamide (DBz2DH2)

in order to study the behaviour of these ligands with a greater st eric hindrance. All these complexes are well crystallized.

Those obtained

from HAc and a strong mineral acid are blue-violet and have the general stoichiometry NiL2X 2 (X:CI,Br,I,CIO 4 for DCH2DH 2; X=CI, ~r, CIO 4 for DBz2DH2).

The chlorides contain two molecules of HAc

in the stoichiometric unit. DCH2DH 2 give from neutral solutions a crystalline red complex Ni(DCH2DH)2.2EtOH,

ethanolic in which

two protons of the ligand molecules are substituted by the metal ion without forming a polymer, dithiooxamides

as they do in the case of other

(1,2). All the complexes are diamagnetic.

The I.R. spectra of these complexes, according to the assign ments given for the ligands

(5), indicate that nickel(ll)

299

is

NICKEL(II) COMPLEXES

300

S,N-eoordinated

to the ligands

other dithiooxamides split.

The increase

corresponds

as in the analogous

The v(CN)

in v(CN)

and ~(CS)

in V(CN)

and the increase

in v(CS)

The far I.R. bands of the ligands the complexes

of

(Table I) are

in v(CS)

S-bonded

to that half of the molecule N-bonded

complexes

bands

and the decrease

to that half of the molecule

The decrease sponds

(3).

Vol. 8, No. 3

frequencies

to the metal.

frequencies

to the metal

corre-

(3,6).

unaltered in -I in the region of 505-445 cm ,

which show new bands

are practically

assignable 342-290

to v(NiN) modes (3,9,10), and new bands in the region -I cm , assignable to v(NiS) modes (3,11,12).

As for the nickel(ll)

complexes

of other dithiooxamides (3), -I two new strong bands appear at 1200-1190 and 1125-1120 cm for the N i ( D C H 2 D H 2 ) X 2 complexes and apparently -I 1135 cm for the Ni(DBz2DH2)X 2 complexes. also appear

in other similar

modes being

enhanced

The electronic plexes

through nitrogen

Two bands may correspond

spectra

signments

complexes

symmetry

four directions

to the two differ-

15.2-16.0 k_K, which may

for a square

with chromophores

coordination [NiN2S 2] (13).

and ligand atoms pointing

intermediate

By using a correction ~ I (16)

to the xy axes

The a~

factor

•

in

(15) of 2800 cm -I the splitting

di~hiooxamides

t

(3)

This value

series of the

(~I in kK) as follows:

Dmtnmooxammde~18.4) < DCH2DH 2 = DBzDiI2(18.7) dithiooxamide(19.1)

to the metal

is 18.7 k~ for both perchiorates.

other S,N coordinating .

of the

(14).

places DCH2DH 2 and DBzDH 2 in the spectrochemical

~

stronger

of the d-d band in Table I are made by assuming a D2h

trams-planar

parameter

to V(RN)

(Table I) of these low-spin NiL2X 2 co~

as characteristic

low-spin Ni(ll)

which

of the ligand molecule.

show the first band in the range

be considered

These new bands,

(8), were assigned

by a complexation

than through sulphur. ently bonded halves

complexes

only one band at 1165-

< N,N'-dihydroxyethy~

< N,N'-dimethyldithiooxamide(19.6).

The complex Ni(DCH2DH)2"2EtOH

has identical

electronic

spec-

Vol. 8, No. 3

NICKEL(II) COMPLEXES

301

tra in the solid state and in CHCI 3 or pyridine solutions. dicates

that

This i~

even in the strong coordinating pyridine the complex

has the same c o o r d i n a t i o n as in the solid. tions show that the bamds at 18.7-19.1

The high molar

extinc-

and 20.2 kK are charge-

- t r a n s f e r rather than d-d in character. The I.R. bands of the p e r c h l o r a t e tion of this ion from T d symmetry n a t i v e axial

ion correspond to a deforma-

(7). Any possibility of a coord~

interaction on the metal may be excluded on account

of the good constancy of the d-d bands of the complexes of the same ligand,

irrespective of the anions.

tion may be better

The p e r c h l o r a t e deforma-

explained as being due to an electrostatic

teraction of this ion either with the metal with a positively

in-

ion or, more probably,

charged HHN-group of the coordinated ligand

(3).

This i n t e r a c t i o n may also take place for the other anions CI-,Br-, I-, since the I.R. and the electronic spectra of these complexes are very similar. Experimental All reagents were of the best chemical grade. Acid used: HAc(glacial),

HCI(37%),

HBr(48%),

HI(57%),

HCI04(60%).

For the

p r e p a r a t i o n of the complexes Ni acetate and the ligand were separately dissolved

in glacial HAc containing the mineral

ratio of about 9:1.

The nickel

the solution of the ligand.

solution was added at about 60 ° to

P r e c i p i t a t i o n was instantaneous

cept for N i ( D C H 2 D H 2 ) 2 C I 2 . 2 H A c

in air. N i ( D B z 2 D H 2 ) 2 C I 2 . 2 H ~ c

was obtained only from glacial HAc containing about

10% of anhy-

N i ( D C H 2 D H ) 2 - 2 E t 0 H was prepared by m i x i n g the Et0H sol~

tions of Ni acetate and of the iigand and p r e c i p i t a t e s Table

ex-

(12 h.) and N i ( D B z 2 D H 2 ) 2 C I 2 . 2 H A c

(72 ~), which are also very unstable

drous HCI.

acid in the

in the molar ratio M:L=I:7,

in 48 h at 5°C. Analytical results are given in

I.

~dagne~=c susceptibilities

were measured and infrared and elec-

302

NICKEL(II)

COMPLEXES

V o l . 8, N o . 3

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Vol. 8, No. 3

NICKEL(II) COMPLEXES

303

~ronic spectra were recorded by conventional methods as previously described

(3). Acknowl ed~em ent s

This work was supported by financial aid from the Consiglio Nazionale delle Ricerche of Italy. References I. P.Ray and R.M.Ray,

J.Indian Chem. Soc.,_3,

2. R.N.Hurd, G.De La Mater, G.C.~cElheny Chem. Soc., 84, 4454 (1960). 3. G.Peyronel, in press.

G.C.Pellacami

A.Pigmedoli

5. H.0.Desseyn and ~.A.Herman,

7. I.M.Procter, (1968).

B.J.Hataway

Inorg. Chim.Acta,

and G.Benetti,

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23A, 2457 (1967)

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Trans.Metal

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Spectrochim.Acta,

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Inorg.

J.Chem. Soc.(A),

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J.Am.

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and L.V.Peiffer,

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118 (1926).

E.Arnold

Inorg.Nucl.

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16. H.B.Gray and C.J.Ballhausen,

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