Novel Schiff bases with oxime groups and their homo- and heteronuclear copper(II) complexes

Article abstract of DOI:10.1135/cccc20071383

Two novel tetradentate Schiff bases containing oxime groups and their homodinuclear, homotrinuclear Cu(II) and heterodinuclear Cu(II)-Mn(II) and Cu(II)-Co(II) complexes were synthesized. The Schiff base ligands (H ₂L¹ and H₂

Full text of DOI:10.1135/cccc20071383

Novel Schiff Bases with Oxime Groups
1383
NOVEL SCHIFF BASES WITH OXIME GROUPS AND THEIR HOMO-
AND HETERONUCLEAR COPPER(II) COMPLEXES
1
2,
3
Bülent DEDE , Fatma KARIPCIN * and Mustafa CENGIZ
Department of Chemistry, Süleyman Demirel University, 32260 Isparta, Turkey;
1
2
3
e-mail: dbulent@fef.sdu.edu.tr, karipcin@fef.sdu.edu.tr, m.cengiz@fef.sdu.edu.tr
Received July 24, 2007
Accepted Septem ber 28, 2007
Two n ovel tetraden tate Sch iff bases con tain in g oxim e groups an d th eir h om odin uclear,
h om otrin uclear Cu(II) an d h eterodin uclear Cu(II)–Mn (II) an d Cu(II)–Co(II) com plexes were
syn th esized. Th e Sch iff base ligan ds (H2L1 an d H2L2) were prepared by con den sin g of
dieth ylen etriam in e with 2-(biph en yl-4-yl)-N-(4-ch loroph en yl)-N′-h ydroxy-2-oxoacetim id-
am ide (HL1) an d 2-(biph en yl-4-yl)-N′-h ydroxy-N-(4-m eth ylph en yl)-2-oxoacetim idam ide
(HL2). Structure assign m en ts are supported by a com bin ation of FT-IR, elem en tal an alyses,
in ductively coupled plasm a optical em ission spectroscopy (ICP-OES), m agn etic susceptibil-
ity, m olar con ductivity an d th erm al an alyses studies. Th e free ligan ds were also ch aracter-
ized by 1H an d 13C NMR spectra. Elem en tal an alyses, stoich iom etric an d spectroscopic data
in dicated th at th e m etal:ligan d ratio is 2:1 for th e din uclear copper(II) com plexes an d 3:2
for th e trin uclear copper(II) com plexes. Th e copper(II) ion s are coordin ated to th e oxim e
an d im in e n itrogen atom s. Pyrolytic decom position occurred in m eltin g th e m etal com -
plexes an d m etal oxides were th e ultim ate products.
Keyw ord s: Sch iff base; Oxim e; Polyn uclear; Th erm och em istry; Copper com plexes.
Due to th e in creasin g use of coordin ation com poun ds in an alytical an d m e-
dicin al ch em istry, in bioch em istry an d pain t an d coatin gs in dustry, plen ti-
ful in vestigators h ave dealt with th ese topics, in particular th e im portan t
role of azom eth in e1 an d oxim e2–4 com plexes. A large n um ber of Sch iff
bases, oxim es an d th eir com plexes h ave been studied for th eir in terestin g
an d im portan t properties, such as th eir ability to reversibly bin d oxygen 5,
catalytic activity in h ydrogen ation of olefin s6, ph otoch rom ic7 an d optical
properties8,9. Syn th eses of n ew Sch iff bases an d oxim es, an d th eir m etal
com plexes con tin ue to be th e aim of m an y recen t in vestigation s10–14
.
Th e design an d syn th eses of n ew bridgin g ligan ds used in polyn uclear
com plexes, as well as th eir ph otoch em ical, ph otoph ysical an d electroch em -
ical properties h ave been in ten sively studied in recen t years, with a focus
on ph otoin duced en ergy- an d electron -tran sfer processes in supram olecular
system s15–17. Th e presen ce of copper(II) ion in th ese com plexes is m ain ly
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© 2007 Institute of Organic Chemistry and Biochemistry
doi:10.1135/cccc20071383

1384
Dede, Karipcin, Cengiz:
n oted in two areas: (i) th e research of th e m agn eto–structural relation sh ip
an d (ii) th e ch aracterization of active sites in m ulticopper protein s10. Cop-
per(II) com plexes sh ow a wide ran ge of biological activities. Som e of th ese
com plexes h ave been kn own as an titum our, an tiviral, an d an ti-in flam -
m atory agen ts. In addition , sin ce copper(II) com plexes, especially with
Sch iff base or oxim e ligan ds, are m odels of ph ysical an d ch em ical beh avior
of biological copper system s, th ey h ave received con siderable atten-
tion 11,18–21. Th e copper(II) com plex of 1,10-ph en an th rolin e h as been th e
first syn th etic tran sition m etal com plex effectively exh ibitin g n ucleolytic
activity22
.
In a previous study9 we in vestigated th e syn th eses, ch aracterization an d
optical properties of m on o- an d trin uclear copper(II) com plexes of a n ovel
tetraden tate Sch iff base. In th e presen t work we report th e syn th eses an d
ch aracterization of h om odi-, h om otrin uclear Cu(II) an d h eterodin uclear
Cu(II)–Mn (II), Cu(II)–Co(II) com plexes with 2,2′-[im in obis(eth ylen en itrilo)]-
bis[2-(biph en yl-4-yl)-N-(4-ch loroph en yl)-N′-h ydroxyacetim idam ide] (1; H2L1)
and 2,2′-[iminobis(ethylenenitrilo)]bis[2-(biphenyl-4-yl)-N′-hydroxy-N-(4-m eth yl-
ph en yl)acetim idam ide] (6; H2L2), see Sch em e 1 an d Figs 1–3.
RESULTS AND DISCUSSION
Preparation of the Schiff base ligands 2,2′-[im in obis(eth ylen en itrilo)]-
bis[2-(biphenyl-4-yl)-N-(4-chlorophenyl)-N′-hydroxyacetim idam ide] (H2L1) and
2,2′-[im inobis(ethylenenitrilo)]bis[2-(biph en yl-4-yl)-N′-h ydroxy-N-(4-m eth yl-
ph en yl)acetim idam ide] (H2L2) was perform ed in four steps from biph en yl
as sh own in Sch em e 1. 4-(Ch loroacetyl)biph en yl was prepared from
ch loroacetyl ch loride an d biph en yl by Friedel–Crafts acylation in th e pres-
en ce of alum in um ch loride23
. 1-(Biph en yl-4-yl)-2-ch loro-2-(h ydroxy-
im in o)eth an -1-on e was obtain ed by reactin g 4-(ch loroacetyl)biph en yl with
alkyl n itrite in th e presen ce of dry HCl gas23. 1-(Biph en yl-4-yl)-2-(4-ch loro-
an ilin o)-2-(h ydroxyim in o)eth an -1-on e an d 1-(biph en yl-4-yl)-2-(h ydroxy-
im in o)-2-(4-m eth ylan ilin o)eth an -1-on e were prepared by reaction of
1-(biph en yl-4-yl)-2-ch loro-2-(h ydroxyim in o)eth an -1-on e with 4-ch loro-
an ilin e or 4-m eth ylan ilin e24
.
Con den sation of th e 2-an ilin o-1-(biph en yl-4-yl)-2-(h ydroxyim in o)eth an -
1-on es with dieth ylen etriam in e gave th e correspon din g products th at were
1
iden tified by elem en tal an d th erm al an alysis, IR, H an d 13C NMR spectra.
Th e replacem en t of th e carbon yl by th e im in e group results in : (i) lower
en ergy of th e ν(C=O) stretch in g in th e IR spectrum an d (ii) a sh ift to h igh er
1
field of the CH=N proton signal in the H NMR spectrum . The m ono- (Fig. 1),
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Novel Schiff Bases with Oxime Groups
1385
2
1
6
SCHEME 1
Syn th eses of th e Sch iff base ligan ds H2L1 (1) an d H2L2 (6)
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Dede, Karipcin, Cengiz:
1
6
FIG. 1
Mon on uclear copper(II) com plexes of H2L1 an d H2L2 (see Sch em e 1)
M = Cu(II)
M = Mn (II)
2
3
4
M = Co(II)
M = Cu(II)
M = Mn (II)
M = Co(II)
7
8
9
FIG. 2
Studied h om odin uclear Cu(II) com plexes 2 an d 7, Cu(II)–Mn (II) com plexes 3 an d 8, an d
Cu(II)–Co(II) com plexes 4 an d 9
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Novel Schiff Bases with Oxime Groups
1387
h om odi- (Fig. 2), h om otri- (Fig. 3), an d h eterodin uclear Cu(II)–Mn (II) an d
Cu(II)–Co(II) com plexes (Fig. 2) were prepared by th e reaction of a ligan d
solution in aceton e with copper(II), m an gan ese(II) or cobalt(II) salts. Th e
details are given in Experim en tal. Th e resultin g solids were in ten sely colored
an d stable in air. Ch aracterization of all th e com poun ds studied is given in
Table I.
NMR Spectra
1H NMR spectra of th e free ligan ds H2L1 (1) an d H2L2 (6) were recorded in
CDCl3. Th e ch em ical sh ifts, expressed in ppm down field from tetram eth yl-
1
silan e, are given in Table II. Th e H NMR spectra of th e ligan ds exh ibited a
broad sin glet at 8.22 an d 8.18 ppm for th e OH proton s of th e oxim e
groups. In th e region of 7.18–7.81 an d 7.11–7.97 ppm , ch em ical sh ifts for
arom atic h ydrogen s were assign ed. Th e ch em ical sh ifts of th e arom atic
am in e proton s of H2L1 an d H2L2 appeared at 6.84 an d 6.94 ppm as sin glets.
Furth erm ore, th e triplets in th e ran ge 1.04–2.41 ppm h ave been assign ed to
proton s of th e m eth ylen e groups of th e triam in e. Th e oth er obtain ed values
1
of H NMR ch em ical sh ifts of th ese com poun ds are given in Table II.
5
10
FIG. 3
Studied h om otrin uclear Cu(II) com plexes 5 an d 10
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Novel Schiff Bases with Oxime Groups
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All th e proton s presen t in th e Sch iff bases exh ibited sign als in th e ex-
pected region s. Th ese data are in good agreem en t with th ose previously
reported for sim ilar com poun ds25. All th e studied com plexes are para-
1
m agn etic; th erefore, th e H NMR spectra could n ot be obtain ed.
Th e 13C NMR spectra of th e free ligan ds were recorded in CDCl3. Th e
ch em ical sh ifts, expressed in ppm down field from tetram eth ylsilan e, are
given in Table III. Th e ch em ical sh ifts of H2L1 an d H2L2 for im in e carbon s
(C=N) were foun d at 186.18 an d 186.42 ppm , respectively. Th e carbon reso-
n an ces of th e oxim e groups are foun d at 148.33 ppm for H2L1 an d 149.22
ppm for H2L2, respectively26,27. All th e sign als in th e 120.89–146.64 ppm
range are assigned to the carbon atom s of the arom atic rings. In the 13C NMR
spectra, th e m eth ylen e carbon s appeared in th e region 46.27–57.08 ppm .
Th e carbon atom of th e m eth yl group was observed at 20.74 ppm for H2L2.
TABLE II
1H NMR ch em ical sh ifts (δ, ppm ) for th e Sch iff base ligan ds H2L1 (1) an d H2L2 (6)
Com pd O–H(ox)
C–H(arom )
N–H
C–H(aliph )
1
6
8.22 (s, 2H) 7.18–7.81 (m , 26H) 6.22 (s, 1H)
6.84 (s, 2H) (Ar-NH-)
1.32 (t, 4H)
2.41 (t, 4H)
8.18 (s, 2H) 7.11–7.97 (m , 26H) 6.51 (s, 1H)
6.94 (s, 2H) (Ar-NH-)
2.45 (s, 6H) (Ar-NH-)
1.04 (t, 4H)
1.47 (t, 4H)
TABLE III
13C ch em ical sh ifts (δ, ppm ) for th e Sch iff base ligan ds H2L1 (1) an d H2L2 (6)
Com pd
Cim
Cox
Carom
Caliph
1
6
186.18
186.42
148.33
149.22
122.37–146.16
120.89–146.64
46.67
56.82
20.74 (Ar-CH3)
46.27
57.08
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IR Spectra
Dede, Karipcin, Cengiz:
IR spectroscopy is a powerful tool for structure determ in ation s of ligan ds
an d m etal ch elates. Th e IR spectra of th e free ligan ds an d th eir com plexes
exh ibit various ban ds in th e 400–4000 cm –1 region (Table IV).
Th e broad ν(OH) ban ds at 3367 an d 3230 cm –1 observed in th e IR spectra
of th e free ligan ds are absen t in th e IR spectra of th eir com plexes with
Cu(II), in dicatin g deproton ation of th e OH groups an d form ation of M–O
bon ds. Th is is supported by th e appearan ce of a n ew ban d in th e region
536–507 cm –1 assign ed to ν(M–O) 28,29. Th e IR spectra of th e copper(II) com -
plexes also sh owed a broad ban d in th e 3502–3566 cm –1 region , in lin e with
th e presen ce of water m olecules coordin ated to th e m etal ion 28
.
IR spectra of H2L1 an d H2L2 exh ibited fairly stron g ban ds at 3383 an d
3389 cm –1 attributable to th e ν(NH) vibration of arom atic am in e groups.
Th e NO stretch in g vibration s of th e ligan ds were observed as m edium -
in ten sity ban ds at 1364 an d 1377 cm –1 (refs30,31).
Stron g ban ds at 1657 an d 1665 cm –1 in th e IR spectra of th e free ligan ds,
assign ed to m odes in volvin g th e im in e group (C=N), sh ifted32–34 to th e
sm aller waven um bers in th e spectra of th e com plexes. Th e ν(C=N) ban ds
for th e oxim e groups lie at 1601 an d 1602 cm –1, as reported for sim ilar lig-
an ds35,36. Coordin ation of th e ligan ds to th e m etal ion s th rough th e
azom eth in e n itrogen atom is expected to reduce th e electron den sity at th e
azom eth in e lin k of th e im in e an d oxim e groups, an d to lower th e ν(C=N)
frequen cy. In th e IR spectra of all th e n ew com plexes, th e ban d due to
ν(C=N) appears at sm aller waven um bers, viz. 1639–1653 cm –1 (im in e) an d
1598–1600 cm –1 (oxim e), bein g in dicative of th e coordin ation of th e
azom eth in e n itrogen to th e m etal cen tres37,38. Th is idea is supported by th e
appearan ce of a n ew ban d at 437–416 cm –1 assign ed to ν(M–N) 28,29. Th e
complexes show also a medium broad band in the region 1187–1145 cm –1, a
strong ban d at 1109–1083 cm –1 an d a weak ban d in th e 626–617 cm –1
ran ge; th ese features are typical for un coordin ated perch lorates29,39,40. Th us
th e IR spectra of th e Sch iff base ligan ds an d th eir m etal com plexes provide
stron g eviden ce of th e com plexation of poten tially m ultiden tate ligan ds.
Molar Conductivity
Th e m olar con ductivity of th e com plexes was an aid in proposin g th eir for-
m ulas. Con ductivity m easurem en ts were carried out in 10–3 M N,N-dim eth yl-
form am ide solution s at 20 °C. Th e com plexes sh owed values between 155
an d 186 S cm –1 m ol–1 (Table I). Th e m olar con ductivities of th e di- an d
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Novel Schiff Bases with Oxime Groups
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Dede, Karipcin, Cengiz:
trinuclear copper(II) com plexes in DMF indicated that com plexes of copper(II)
con tain in g perch lorate ion s beh ave as 1:2 electrolytes10,41
.
Magnetic Studies
Th e m agn etic m om en ts of th e com plexes at room tem perature (Table I) re-
veal th at all th e copper(II) com plexes are param agn etic. Th e m easured m ag-
n etic m om en ts of th e trin uclear copper(II) com plexes are 1.86 an d 1.92 µB
for 5 an d 10, respectively. Th e m agn etic m om en ts for th e h om odin uclear
copper(II) com plexes 2 an d 7 are 1.75 an d 1.82 µB, respectively, at 298 K.
Th ese values are on ly sligh tly lower th an expected for din uclear copper(II)
com plexes, with th e th eoretical value of 1.73 µB per on e d9 copper ion 10
.
Th e stron g an tiferrom agn etic couplin g with in th e h om odi- an d trin uclear
copper(II) com plexes is explain ed by good superexch an ge properties of th e
oxim ato group10. Furth erm ore, th e h eterodin uclear com plexes sh ow µeff
values of 3.64 (3), 2.49 (4), 3.72 (8) an d 2.40 (9) µB. Th ese subn orm al m ag-
n etic m om en t values m ay be explain ed by weak in tram olecular an tiferro-
m agn etic in teraction s42,44
.
Thermal Studies
Th e th erm al beh avior of all th e com plexes was alm ost th e sam e. Th erefore,
on ly four of th e com plexes are discussed h ere in detail. In th erm o-
gravim etry (TG), th e ch an ge in th e weigh t of a com plex is recorded as a
fun ction of tem perature durin g h eatin g. Th e TG curves give in form ation on
th e th erm al stability an d th e products form ed on h eatin g. Th e TG curve is
also supported by th e derivative th erm ogravim etry (DTG) curves.
It is n oted from th e TG an alysis th at th e h om odin uclear Cu(II) com plex 2
loses 91% of its origin al weigh t between 190 an d 840 °C an d th e 9% residue
is m etallic Cu. Th e sam ple decom poses in th ree stages. Th e first decom posi-
tion occurs between 190 an d 210 °C with 1.40% weigh t loss, th e secon d
on e between 210 an d 455 °C with 37.80% weigh t loss an d th e th ird on e
between 455 an d 840 °C with 51.80% weigh t loss.
Th e h om otrin uclear Co(II) com plex 5 sh ows a decom position pattern of
four stages. Th e first step with th e estim ated weigh t loss 1.70% was foun d
with in th e tem perature ran ge 185–204 °C correspon din g to th e loss of two
H2O m olecules. Th e secon d step with th e estim ated weigh t loss of 41.70%,
foun d with in th e tem perature ran ge 204–410 °C, correspon ds to th e loss of
two perch lorate an d four biph en yl groups. Th e rem ain in g decom position
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Novel Schiff Bases with Oxime Groups
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Dede, Karipcin, Cengiz:
steps (at 410–995 °C) with an estim ated weigh t loss 44.10% due to th e loss
of th e oth er groups, leave th e CuO residue.
It was foun d from th e TG an alysis th at th e h om odin uclear Cu(II) com -
plex 7 starts losin g weigh t at 175 °C, wh ich en ds at 965 °C after 90.90%
weigh t loss, leavin g a m etallic Cu residue th at correspon ds to 9.10% of th e
total weigh t. Th e exam in ation of th e TG curve sh owed th at th e com plex
decom poses in th ree stages. Th e sam ple loses 1.50% of th e weigh t between
175 an d 202 °C, 39.30% between 202 an d 495 °C, an d 50.10% between 495
an d 965 °C.
DTG/TG studies sh owed th at th e residual black solid was CuO, wh ich
correspon ds to a th eoretical weigh t of 12.50% of th e h om otrin uclear Cu(II)
com plex 10. Th is Cu(II) com plex decom poses in th ree stages by losin g 2.20,
32.85 an d 52.45% of its weigh t durin g pyrolysis. Th e tem perature ran ges
of th ese decom position s are foun d at 170–205, 205–260 an d 379–1000 °C,
respectively.
Th e th eoretical an d experim en tal per cen t weigh t losses obtain ed from
th ese decom position stages are in good agreem en t. Th e critical data an d
values deduced from th e presen t study are sum m arized in Table V.
EXPERIMENTAL
Ph ysical Measurem en ts
All th e solven ts, am in es an d m etal salts (Cu(ClO4)2·6H2O, Mn (OAc)2·4H2O, Co(OAc)2·4H2O)
used for th e syn th eses an d ph ysical m easurem en ts were purch ased from Aldrich , Baker an d
Merck, an d used as received. 1H NMR an d 13C NMR spectra of th e ligan ds 1 an d 6 were re-
corded in CDCl3 solution s, with TMS as th e in tern al stan dard in th e Cen tral Laboratory at
METU-An kara, Turkey. IR spectra (4000–400 cm –1
) were recorded on a Sh im adzu
IRPrestige-21 FT-IR spectroph otom eter as KBr pellets. Th e th erm ogravim etric an alyses (TG
an d DTG) of th e com plexes were m easured in th e Cen tral Laboratory at METU-An kara, Tur-
key. C, H an d N m icroan alyses were determ in ed on a LECO 932 CHNS an alyzer. Mn , Co an d
Cu con ten ts were m easured on a Perkin –Elm er Optim a 5300 DV ICP-OES spectrom eter. Mag-
n etic susceptibilities were obtain ed with a Sh erwood scien tific m agn etic susceptibility bal-
an ce (Model MX1) at room tem perature. Th e con ductivity m easurem en ts were carried out
usin g an Optic Ivym en System con ductivity m eter. Meltin g poin ts were determ in ed with
a digital in strum en t from Electroth erm al m odel IA 9100.
Syn th eses of Ligan ds H2L1 (1) an d H2L2 (6)
2-An ilin o-1-(biph en yl-4-yl)-2-(h ydroxyim in o)eth an -1-on es (HL1 an d HL2) were prepared
accordin g to previously publish ed procedures24. Th ese precursors (30 m m ol, 23.06 g HL1
an d 21.84 g HL2) in absolu te eth an ol (10 m l) an d ad d ed d ieth ylen etriam in e (1.547 g,
15 m m ol) in absolute eth an ol (10 m l) were stirred at room tem perature for 2 h . Th e precipi-
tate was filtered off an d wash ed several tim es with dieth yl eth er an d dried over P2O5.
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Novel Schiff Bases with Oxime Groups
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Syn th eses of Com plexes
Caution: Perch lorate salts of m etal com plexes are poten tially explosive an d sh ould be h an -
dled in sm all quan tities.
[Cu(H2L1)(H2O)]ClO4 and [Cu(H2L2)(H2O)]ClO4. Th e copper(II) com plexes were prepared in
a sim ilar m an n er30. A solution of Cu(ClO4)2·6H2O (370 m g, 1 m m ol) in aceton e (25 m l) was
added to th e ligan d solution (1 m m ol) in aceton e (30 m l). Th is m ixture was refluxed for 1 h
un der stirrin g. After strippin g off th e excess solven t un der reduced pressure, a crude oily
product was obtain ed. Th e m on on uclear copper(II) com plexes were used with out furth er pu-
rification .
[Cu(L1)(H2O)Cu(phen)2](ClO4)2 (2) and [Cu(L2)(H2O)Cu(phen)2](ClO4)2 (7). Th e m on on uclear
copper com plex (1 m m ol) was added to Et3N (101 m g, 1 m m ol) in MeOH (25 m l) an d th e
m ixture was stirred for 0.5 h . Th e solution s of Cu(ClO4)2·6H2O (370 m g, 1 m m ol) in MeOH
(10 m l) an d 1,10-ph en an th rolin e m on oh ydrate (397 m g, 2 m m ol) in MeOH (10 m l) were
successively added to th e resultin g m ixture, wh ich was refluxed for 3 h . Th e product was fil-
tered off, wash ed with H2O, MeOH an d Et2O, an d dried over P2O5.
[Cu(L1)(H2O)Mn(phen)2](ClO4)2 (3) and [Cu(L2)(H2O)Mn(phen)2](ClO4)2 (8). Th e m on o-
n uclear copper com plex (1 m m ol) was m ixed with Et3N (101 m g, 1 m m ol) in MeOH (20 m l)
an d stirred for 0.5 h . Th e solution s of Mn (OAc)2·4H2O (268 m g, 1 m m ol) in MeOH (10 m l)
an d 1,10-ph en an th rolin e m on oh ydrate (397 m g, 2 m m ol) in MeOH (10 m l) were succes-
sively added to th e resultin g solution . A stoich iom etric am oun t of NaClO4 (123 m g, 1 m m ol)
was th en added to th e resultin g m ixture th at was refluxed for 3 h . Th e product was filtered
off, wash ed with H2O, MeOH an d Et2O, an d dried over P2O5.
[Cu(L1)(H2O)Co(phen)2](ClO4)2 (4) and [Cu(L2)(H2O)Co(phen)2](ClO4)2 (9). Th e m on on uclear
copper com plex (1 m m ol) was m ixed with Et3N (101 m g, 1 m m ol) in MeOH (20 m l) an d
stirred for 0.5 h . Th e solution s of Co(OAc)2·4H2O (249 m g, 1 m m ol) in MeOH (10 m l) an d
1,10-ph en an th rolin e m on oh ydrate (397 m g, 2 m m ol) in MeOH (10 m l) were successively
added to th e resultin g solution . A stoich iom etric am oun t of NaClO4 (123 m g, 1 m m ol) was
th en added to th e resultin g m ixture wh ich was refluxed for 5 h . Th e product was filtered
off, wash ed with H2O, MeOH an d Et2O, an d dried over P2O5.
[Cu3(L1)2(H2O)2](ClO4)2 (5) and [Cu3(L2)2(H2O)2](ClO4)2 (10). A m ixture of m on on uclear
copper com plex (2 m m ol), Cu(ClO4)2.6H2O (370 m g, 1 m m ol) an d Et3N (202 m g, 2 m m ol)
in aceton e (25 m l) was refluxed for 2 h . Th e resultin g solution was filtered wh ile h ot an d
con cen trated slowly. As th e solution cooled, a powder product precipitated. It was isolated
by vacuum filtration , wash ed with Et2O an d dried over P2O5.
Th e colors, yields, m eltin g poin ts, elem en tal an alyses, m agn etic susceptibility an d m olar
con ductivity values of th e oligon uclear com plexes are given in Table I.
CONCLUSION
New Sch iff base ligan ds 1 an d 6 (Sch em e 1) an d th eir h om odi- an d
h om otrin uclear copper(II) an d h eterodin uclear copper(II)–m an gan ese(II),
copper(II)–cobalt(II) com plexes were syn th esized an d ch aracterized by ele-
m en tal an alyses, TG/DTG, ICP-OES, m agn etic susceptibility, m olar con duc-
tivity, an d FT-IR, 13C an d 1H NMR spectroscopies. Elem en tal an alyses,
stoich iom etric an d spectroscopic data of th e m etal com plexes in dicate th at
Collect. Czech. Chem. Commun. 2007, Vol. 72, No. 10, pp. 1383–1397

1396
Dede, Karipcin, Cengiz:
in th e din uclear com plexes, in wh ich th e first Cu(II) ion is com plexed by
n itrogen atom s of th e oxim e an d im in e groups, th e secon d ion (Cu(II),
Mn (II), Co(II)) is ligated with dian ion ic oxygen atom s of th e oxim e groups
an d lin ked to th e 1,10-ph en an th rolin e n itrogen atom s. Th e trin uclear cop-
per(II) com plex was form ed by coordin ation of th e th ird Cu(II) ion by four
dian ion ic oxygen atom s in th e two m on on uclear copper(II) com plex m oi-
eties. All com plexes of th ese ligan ds h ave a square-pyram idal or octah edral
structure, except th e secon d copper(II) in th e trin uclear com plexes. Th e
th erm al an alyses of th ese ch elates sh ow th at th e com plexes th erm ally de-
com pose in 4–5 con secutive steps. Th e fin al decom position products are
th e correspon din g m etal or m etal oxides.
We wish to thank the Research Fund of the Süleyman Demirel University, Turkey (Grant No.
961-D-04).
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