Complexes of hexadentate nso donor ligands-III. Nickel(II) complexes of 1,3-di(o-salicylaldiminophenylthio)propane and 1,2-di(o-salicylaldiminophenylthio)xylene

Article abstract of DOI:10.1016/S0277-5387(98)00127-2

Nickel(II) complexes of the hexadentate N₂S₂O₂ donor ligands, 1,3-di(o-salicylaldiminophenylthio)propane (H₂DSALPTP) and 1,2-di(o-salicylaldiminophenylthio)xylene (H₂DSALPTX) have been synthesised and characterised. H₂DSALPTP reacted with NiCl₂.6H₂O or Ni(ClO₄)₂.6H₂O in presence of ammonia to give the complex [Ni(DSALPTP)] (1). H₂DSALPTX reacted smoothly with Ni(ClO₄)₂ to yield the corresponding complex [Ni(DSALPTX)] (2). The ligand did not react with NiCl₂ in the absence of ammonia but in its presence produced the complex (2). The molecular and crystal structure of [Ni(DSAL PTX)] exhibits a very unusual deployment of the six donor sites of the ligand. It crystallises in the orthorhombic system with space group P2₁2₁2₁. In dichloromethane solution both the complexes are found to exhibit Ni(II)Ni(III) redox couples in their cyclic voltammograms at room temperature with E₁₂ values 0.87 and 0.78 V (vs. AgAgCl).

Full text of DOI:10.1016/S0277-5387(98)00127-2

Polyhedron Vol[ 06\ No[ 08\ pp[ 2328Ð2333\ 0887
Þ 0887 Elsevier Science Ltd
Pergamon
All rights reserved[ Printed in Great Britain
9166Ð4276:87 ,08[99¦9[99
\
PII] S9166Ð4276"87#99016Ð1
Complexes of hexadentate NSO donor ligands!
III[ Nickel"II# complexes of
0\2!di"o!salicylaldiminophenylthio#propane and
0\1!di"o!salicylaldiminophenylthio#xylene
Shefali Pal\a Saktiprosad Ghosh\aꢀ Gurucharan Mukherjeeb and
Asok Kumar Nandic
aDepartment of Inorganic Chemistry\ Indian Association for the Cultivation of Science\ Jadavpur\
Calcutta\ 699 921\ India
bDepartment of Chemistry\ Presidency College\ Calcutta\ 699 962\ India
cCentral Glass and Ceramic Research Institute\ Calcutta\ 699 921\ India
"Received 7 October 0886^ accepted 16 March 0887#
Abstract*Nickel"II# complexes of the hexadentate N1S1O1 donor ligands\ 0\2!di"o!salicylaldimino!
phenylthio#propane "H1DSALPTP# and 0\1!di"o!salicylaldiminophenylthio#xylene "H1DSALPTX# have been
synthesised and characterised[ H1DSALPTP reacted with NiCl1[5H1O or Ni"ClO3#1[5H1O in presence of
ammonia to give the complex ðNi"DSALPTP#Ł "0#[ H1DSALPTX reacted smoothly with Ni"ClO3#1 to yield the
corresponding complex ðNi"DSALPTX#Ł "1#[ The ligand did not react with NiCl1 in the absence of ammonia
but in its presence produced the complex "1#[ The molecular and crystal structure of ðNi"DSAL PTX#Ł exhibits
a very unusual deployment of the six donor sites of the ligand[ It crystallises in the orthorhombic system with
space group P101010[ In dichloromethane solution both the complexes are found to exhibit Ni"II#:Ni"III# redox
couples in their cyclic voltammograms at room temperature with E0:1 values 9[76 and 9[67 V "vs[ Ag:AgCl#[
Þ 0887 Elsevier Science Ltd[ All rights reserved
Keywords] hexadentate NSO!donors^ Ni"II# complexes^ X!ray and molecular structure^ electrochemical studies[
———————————————————————————————————————————————
Hexacoordinating ~exidentate ligands with ONS remarkably low oxidation potential for the nickel"II#:
donor sites in strategic positions of the donor frame! nickel"III# redox couple ð2b\6Ł[ In this paper we report
work are not commonly encountered in coordination the synthesis\ characterisation and cyclic voltam!
chemistry and our group has explored some of them metric studies of the nickel"II# complexes of two
previously ð0\ 1Ł[ Disclosure of the fact that nickel is N1S1O1 donor ligands[ The molecular structure of
an essential constituent of several hydrogenases ð2Ł ðNi"DSALPTX#Ł is also reported and it reveals a very
and that nickel sites are believed to have a distorted large distortion of the coordination environment
octahedral arrangement consisting of 1 or 2 sulphur around the nickel"II# acceptor centre from the perfect
atoms and the rest nitrogen and:or oxygen atoms ð3\ octahedron[
4Ł prompted us to undertake the study of nickel com!
plexes of the ligands which have N1S1O1 donor sites[
Nickel bound to sulphur and nitrogen:oxygen is also
present in carbon monoxide dehydrogenases ð5Ł[ The
EXPERIMENTAL
catalytic properties of hydrogenase arise from the
Synthesis of the li`ands
They were prepared by methods described earlier
ꢀ Author to whom correspondence should be addressed[
ð0Ł[
2328

2339
S[ Pal et al[
full matrix least!square re_nement coverged at R to
Synthesis of the complexes
9[942[ Crystallographic data and additional details
ðNi"DSALPTP#Ł"0#] A solution of NiCl1[5H1O regarding data collected and re_nement are given in
"9[13 g\ 0 mmol# or Ni"ClO3#1[5H1O "9[22 g\ 0 mmol# Table 0[
in methanol "19 cm2# was added to a stirring solution
of the ligand "9[38 g\ 0 mmol# in chloroform "19 cm2#
Structure description
and the mixture was stirred for 0 h[ A few drops of
5"N# NH2 was then added to the mixture[ The mixture
The compound ðNi"DSALPTX#Ł crystallises in the
was further stirred for 37 h[ Red precipitate separated
P101010 space group with four molecules in general
out which was recrystallised from methanol "yields]
position[ The ligand binds the Ni"II# acceptor centre
64)#[
in a distorted octahedral pattern[ The square base of
ðNi"DSALPTX#Ł "1#] This complex was prepared
the octahedron is de_ned by the O"A#\ S"B#\ S"A# and
by the same procedure as above by taking NiCl1[5H1O
O"B# atoms with two nitrogen N"A# and N"B# in the
"9[13 g\ 0 mmol# as the starting metal salt and
two apical positions[ Selected bond lengths and bond
H1DSALPTX "9[45 g\ 0 mmol# as the ligand\ with a
angles are given in Table 1 and a few selected torsion
few drops of 5"N# NH2[ The complex was recrys!
angles are listed in Table 2[ The two phenolate oxygen
tallised from methanol with an yield of about 69)[
and thioether sulphur donors occupy cis!positions of
Ni"ClO3#1[5H1O readily reacts with the ligand in the
the distorted square plane de_ned by O"A#ÐO"B#Ð
same ratio in absence of NH2 to give the same orange!
S"A# and S"B# with the Ni"II# ion centrally placed on
red product[ It was recrystallised from methanol "yield
it with a mean deviation of −9[901"1#A[ The bite
64)#[
Physical measurements
Table 0[ Crystal data and structure re_nement for ðNi"D!
Physical measurements were done as reported in
our earlier communications ð0\ 1Ł[ Electrochemical
SALPTX#Ł "1#
data were collected with a BAS CV!16 and a BAS
model X!Y recorder at 187 K[ The electrodes used
were ~at platinum disc working electrode\ Pt wire Formula weight
Identi_cation code
Empirical formula
"1#
C23H15N1NiO1S1
506[39
Temperature
Wavelength
Crystal system
Space group
Unit cell dimensions
182"1# K
0[43076 A
Orthorhombic
P101010
a ꢁ 02[9749"09# A
a ꢁ 89>
auxiliary electrode and a Ag:AgCl reference electrode[
Crystal structure determination of ðNi"DSALPTX#Ł "1#
Ä
X!ray data were collected in Enraf!Nonius!CAD!3
di}ractometer for a crystal mounted on top of a glass
_bre[ The unit cell parameters were determined from
a least!square re_nement of 06 high angle re~ections[
Ä
b ꢁ 03[0049"09# A
b ꢁ 89>
c ꢁ 04[141"2# A
Ä
g ꢁ 89>
1706[9"5# A
2
Ä
The three intensity controlled re~ections "!2 0!1\ 2!0! Volume
Z
3
1\ !3!2!3# checked every hour\ showed no signi_cant
variations "29[4)#[ The intensities were corrected for
Lorentz!polarisation e}ects and an empirical absorp!
tion correction was also made ð7Ł[ A total of 2149
unique re~ections measured contained 2007 with
Fo − 3s"Fo#[ The structure was solved by direct
methods using the program\ SHELXS!75 ð8Ł which
revealed the positions of all the non!hydrogen atoms[
The program SHELXL!82 ð09Ł was used to re_ne the
Density "calculated#
Absorption coe.cient
F"999#
0[345 gm:cm2
1[548 mm−0
0179
Crystal size
9[19×9[19×9[14 mm
3[16 to 63[80>
Theta range for
data collection
Index ranges
9 ¾ h ¾ 05\ 9 ¾ k ¾ 06\
9 ¾ l ¾ 08
2149
Re~ections collected
structure[ Re_nement on F using anisotropic dis! Unique re~ections
2149
2007
Fo − 3s"Fo#
placement parameters for all non!hydrogen atoms was
performed[ Positions of 00 hydrogen atoms were
located from the di}erence Fourier map[ The other
03 residual hydrogen atoms were placed in their cal!
culated positions with a temperature factor 0[1 times
the Ueq[ of the parent atom to which it is attached[
Coordinates of the 00 hydrogen atoms and their iso!
tropic temperature factors were re_ned[ Figure 0
shows thermal ellipsoid of the molecule\ excluding the
hydrogen atoms for the clarity of the _gure[ The _nal
Re_nement method
Full!matrix least!squares
on F
2149:9:304
9[181
Data:restraints:parameters
Goodness!of!_t on Fo
Final R indices
R ꢁ 9[9416
ðFo × 1s"Fo#Ł
R indices "all data#
Extinction coe.cient
Largest di}[ peak and hole
R ꢁ 9[9432
9[9907"2#
0[912 and −9[588 e[ Aý−2

Complexes of hexadentate NSO donor ligands!III
2330
Fig[ 0[ The thermal ellipsoid of ðNi"DSALPTX#Ł excluding the hydrogen atoms[
angles involving the two sulphur atoms S"A# and S"B# a benzene ring and the dihedral angles of each chelate
generates highly distorted seven membered ring NiÐ ring with its corresponding benzene ring lie in the
S"B#ÐC"3B#ÐC"2B#ÐC"2A#ÐC"3A#ÐS"A#[ Each bite range of 5Ð05>[
angle corresponding to a pair of nitrogen and oxygen
donors attached to the Ni"II# centre is found to form
two six membered rings "NiÐOÐC"06#ÐC"01#ÐC"00#Ð
N# and the NÐS donor pairs to create two _ve mem!
bered chelate rings "NiÐSÐC"4#ÐC"09#ÐN#[ The bite
RESULTS AND DISCUSSION
The complexes synthesised and characterised dur!
angle corresponding to the pair S"A#ÐNiÐS"B#\ O"A#Ð ing the present investigation are ðNi"DSALPTP#Ł "0#
NiÐO"B# are 85[88"4#> and 85[6"1#> respectively and and ðNi"DSALPTX#Ł "1# in which both the ligands
for the other other pair O"A#ÐNiÐS"B# and O"B#ÐNiÐ function as dibasic hexadentate donors[ The ligand
S"A# are 70[86"02#> and 73[89"03#> respectively[ The H1DSALPTP did not react at all with either NiCl1 or
severe distortion of the coordination octahedron Ni"ClO3#1 in the absence of ammonia\ but
being clearly manifested in the values of the angles at H1DSALPTX is found to react with Ni"ClO3#1 in
the metal centre generated by the six donor points[ absence of NH2 to produce
a yellowish!green
The observed bond distances "vide Table 1# fall well compound[ On recrystallisation from methanol it yiel!
within the range found in most of the distorted octa! ded the orange!red compound "1#[ However\
hedral Ni"II# complexes accommodating thioether H1DSALPTX does not react with NiCl1 without the
sulphur coordination ð00Ł[ The large distortion of the presence of ammonia[ When\ however\ the ligand is
coordination octahedron is probably arising due to reacted with Ni"ClO3#1 in presence of ammonia\ a
the unusual orientation of the donor sites of the ligand di}erent compound separated out which was ident!
which is very di.cult to anticipate and is a clear indi! i_ed as ðNi"DAPTX#"NH2#Ł"ClO3#1\ H1DAPTX being
cation of the ~exidentate nature of the ligand[
the diamine dithioether ligand 0\1!di"o!amino!
No hydrogen bonding or any intermolecular short phenylthio#xylene whose Pd"II#\ Ni"II# and Cu"II#
contacts are observed in the lattice[ The molecules are compounds were reported earlier ð01\ 02Ł[ It is quite
packed in the lattice by intermolecular van der Waals probable that base hydrolysis of the Schi} base
forces[ Each _ve!membered and six!membered chelate generated the ligand in situ which then coordinated to
ring formed with the Ni"II# ion is also attached with the Ni"II# ion[ Single crystals for X!ray di}raction

2331
S[ Pal et al[
Table 1[ Selected bond lengths ðAýŁ and angles ð>Ł for ðNi"DSALPTX#Ł
Bond lengths "Aý# and angles "># involving Ni atom
NiÐO"B#
NiÐO"A#
NiÐN"B#
0[877"3#
0[884"3#
1[921"3#
85[6"1#
80[3"1#
77[1"1#
89[2"1#
89[9"1#
066[6"1#
73[89"03#
062[24"01#
NiÐN"A#
NiÐS"A#
NiÐS"B#
N"B#ÐNiÐS"A#
N"A#ÐNiÐS"A#
O"B#ÐNiÐS"B#
O"A#ÐNiÐS"B#
N"B#ÐNiÐS"B#
N"A#ÐNiÐS"B#
S"A#ÐNiÐS"B#
1[934"4#
1[337"1#
1[365"1#
87[13"03#
72[46"02#
063[40"01#
70[86"02#
72[13"02#
84[97"02#
85[88"4#
O"B#ÐNiÐO"A#
O"B#ÐNiÐN"B#
O"A#ÐNiÐN"B#
O"B#ÐNiÐN"A#
O"A#ÐNiÐN"A#
N"B#ÐNiÐN"A#
O"B#ÐNiÐS"A#
O"A#ÐNiÐS"A#
Bond lengths and angles in the _ve!membered ring
S"A#ÐC"4A#
C"4A#ÐC"09A#
N"A#ÐC"09A#
C"6B#ÐC"7B#ÐC"8B#
C"4B#ÐC"09B#ÐN"B#
C"09B#ÐN"B#ÐNi
C"4B#ÐS"B#ÐNi
0[655"5#
0[302"7#
0[397"6#
S"B#ÐC"4B#
C"4B#ÐC"09B#
N"B#ÐC"09B#
C"6A#ÐC"7A#ÐC"8A#
C"4A#ÐC"09A#ÐN"A#
C"09A#ÐN"A#ÐNi
C"4A#ÐS"A#ÐNi
0[651"4#
0[287"6#
0[317"6#
019[5"5#
007[5"4#
007[0"3#
83[5"1#
010[7"5#
007[2"4#
006[3"2#
82[9"1#
Bond lengths and angles in the six!membered ring
N"A#ÐC"00A#
C"00A#ÐC"01A#
C"01A#ÐC"06A#
O"A#ÐC"06A#
C"00A#ÐN"A#ÐNi
N"A#ÐC"00A#ÐC"01A#
C"00A#ÐC"01A#ÐC"06A#
O"A#ÐC"06A#ÐC"01A#
C"06A#ÐO"A#ÐNi
C"3A#ÐS"A#ÐNi
0[186"6#
0[324"7#
0[329"7#
0[173"5#
N"B#ÐC"00B#
C"00B#ÐC"01B#
C"01B#ÐC"06B#
O"B#ÐC"06B#
C"00B#ÐN"B#ÐNi
N"B#ÐC"00B#ÐC"01B#
C"06B#ÐC"01B#ÐC"00B#
O"B#ÐC"06B#ÐC"01B#
C"06B#ÐOBÐNi
0[181"6#
0[323"7#
0[309"7#
0[181"6#
011[3"3#
016[3"4#
012[1"4#
014[6"4#
014[4"3#
011[9"3#
015[6"4#
012[1"4#
013[3"4#
013[2"2#
002[6"1#
Bond lengths and angles in the seven!membered ring
S"A#ÐC"3A#
C"2A#ÐC"2B#
C"2A#ÐC"3A#
S"B#ÐC"3B#
0[726"5#
0[399"09#
0[494"8#
0[716"5#
0[402"7#
C"3B#ÐS"B#ÐNi
014[3"1#
005[0"3#
011[2"5#
010[7"5#
097[7"3#
C"2B#ÐC"3B#ÐS"B#
C"2A#ÐC"2B#ÐC"3B#
C"2B#ÐC"2A#ÐC"3A#
C"2A#ÐC"3A#ÐS"A#
C"2B#ÐC"3B#
Table 2[ Lists of selected torsion angles for ðNi"DSALPTX#Ł
Atoms de_ning the torsion angles
Angle ">#
Atoms de_ning the torsion angles
Angle ">#
N"B#ÐNiÐO"A#ÐC"06A#
N"A#ÐNiÐO"A#ÐC"06A#
O"B#ÐNiÐS"A#ÐC"4A#
S"B#ÐNiÐS"A#ÐC"4A#
O"A#ÐNiÐS"A#ÐC"4A#
−034[8"3#
21[6"3#
−64[8"1#
098[1"1#
17[6"1#
N"B#ÐNiÐS"A#ÐC"4A#
N"A#ÐNiÐS"A#ÐC"4A#
O"B#ÐNiÐO"A#ÐC"06A#
S"B#ÐNiÐO"A#ÐC"06A#
−055[6"1#
03[8"1#
011[8"3#
−51[4"3#
were grown from methanol!ether solution[ Two com! hydrolysis of the imine moiety occurred leading to the
pounds were identi_ed in the crop of crystals[ One rupture of the Schi} base ligand to produce sal!
was the complex "1# and the other one was the Ni"II#! icylaldehyde\ which led to the formation of the Ni"II#
salicylaldehyde complex[ This indicates that partial salicylaldehyde complex[

Complexes of hexadentate NSO donor ligands!III
2332
Table 3[ Analytical dataa\ electrical conductivityb\ magnetic moments\ infrared and electronic spectralc data for the complexes
LM
C
H
N
Ni
"ohm!0 cm1
mol!0#
me}
n"C1N#: n"NiÐS#
lmax\ cm!0
Complex
")#
"B[M[#
"cm!0#
"e\ dm2 mol!0 cm!0#
ðNi"DSALPTP#Ł "0#
51[4
"51[6# "3[2#
3[0
3[8
09[8
2[3
5[8
1[84
2[14
0594
0489
294
259
06130"sh#\ 11616
"06\318#\ 23371
"13\534#
"4[94# "09[5#
ðNi"DSAL PTX#Ł "1#
55[3
3[0
3[2
8[8
06746"sh#
"55[1# "3[1#
"3[4#
"8[4#
11877"0\683#\
20149"27\166#
27350"03\627#
aCalculated values in parentheses[
bMeasured in nitromethane[
cMeasured in dichloromethane[
Infrared\ electronic spectra\ ma`netic moment and con! 49Ð24 cm−0 red shift of the n"ÐSÐCH1# mode of the
ductance
ligands observed as split bands at 699 and 549 cm−0
for H1DSALPTP and at 559 and 539 cm−0 for
In the IR spectra of the complex ðNi"DSALPTP#Ł"0# H1DSALPTX[ Bands observed below 399 cm−0
and ðNi"DSALPTX#Ł"1# the n"OÐH# band of the cor! "Table 3# "which are absent in the spectra of the ligand#
responding ligands observed at 2499 and 2399 cm−0 are attributed to NiÐS linkage[ These observations are
respectively are absent due to the coordination of the in complete agreement with X!ray crystallographic
deprotonated phenolic ÐOH to the Ni"II# acceptor data[ The electronic spectral data supports the octa!
centre[ The n"C1N# bands of the ligands observed at hedral stereochemistry of the complexes "vide Table
0509 and 0599 cm−0 respectively are red shifted by 4Ð 3#[ ðNi"DSAL PTP#Ł and ðNi"DSAL PTX#Ł both exhi!
09 cm−0 in the spectra of the complexes "0# and "1# bit bands in the 06\999 cm−0 region[ The expected
pointing to the involvement of the azomethine nitro! lower energy band could not be detected as it is out
gen in coordination[ In the complexes "0# and "1#\ of the range of the scanning instrument[ The third d!
bonding from the thioether sulphur is indicated by the d band expected in the higher energy region could not
be identi_ed due to the presence of intense charge!
transfer bands in the UV region[ Both the complexes
exhibit normal room temperature magnetic moment
values of 1[84Ð2[14 B[M[ and both behave as non
electrolytes in nitromethane solution[ The _ndings
corroborate that both the phenolic!OH are depro!
tonated during complexation\ the ligands co!
ordinating as their dianions DSALPTP−1 and DSAL
PTX−1
[
Electrochemical studies
Cyclic voltammograms of ðNi"DSALPTP#Ł and
ðNi"DSALPTX#Ł are shown in Fig[ 1 with peak poten!
tials listed in Table 4[ Ni"II#!Ni"III# oxidation poten!
tial data in the case of thioether complexes generally
lie in the range\ 9[2Ð9[7 V ð03Ł[ The redox behaviour
of the complexes have been examined in dichloro!
methane solution[ The cyclic voltammogram of
ðNi"DSALPTP#Ł exhibits a quasi!reversible Ni"II#:
Ni"III# redox couple centered at 9[76 V vs[ Ag:AgCl
and that of ðNi"DSALPTX#Ł displays a reversible
couple at 9[67 V[ Therefore the E0:1 values of these
complexes lie at the higher end of the thioether con!
taning Ni"II# species indicating that Ni"II# is fairly
stabilised in both the complexes[ The ligand
Fig[ 1[ Cyclic voltammograms of solutions of "a# ðNi"D!
SALPTP#Ł "scan rate 199 mvs−0
#
and "b# ðNi"D!
SALPTX#Ł"scan rate 49 mvs−0# in dichloromethane using
platinum electrode and NEt3ClO3 as supporting electrolyte[

2333
S[ Pal et al[
1[ Pal\ S[\ Poddar\ S[ N[\ Ghosh\ S[ and Mukherjee\
Table 4[ Electrochemical dataa
G[\ Polyhedron\ 0884\ 03\ 2912[
Complex
E0:1 "V#
DEp "mV#c
2[ "a# Thompson\ A[ J[\ Nature\ 0871\ 187\ 591^ "b#
Cammack\ R[\ Lancaster\ Jr[\ J[ R[ "ed[#\ The
Bioinor`anic Chemistry of nickel\ VCH\ New
York\ "0877#\ Chapter 7[
ðNi"DSAL PTP#Ł "0#
ðNi"DSAL PTX#Ł "1#
9[76
9[67
299
019
3[ "a# Lindahl\ P[ A[\ Kojima\ N[\ Hausinger\ R[ P[\
Fox\ J[ A[\ Teo\ B[ K[\ Walsh\ C[ T[and Orme!
Johnson\ W[ H[\ J[ Am[ Chem[ Soc[\ 0873\ 095\
2951[ "b# Scott\ R[ A[\ Wallis\ S[ A[\ Czechowski\
M[\ Vartannian\ D[ V[ De\ Gall\ J Le\ Peck\ Jr[\
H[ D[ and Moura\ I[\ J[ Am[ Chem[ Soc[\ 0873\
095\ 2753[
aIn CH1Cl1 "9[0 M TEAP# at a platinum electrode with an
Ag:AgCl reference electrode[
bFrom cyclic voltammetry at a scan rate of 199 mVs−0
cPeak!to!peak separation[
[
4[ "a# Teixeira\ M[\ Moura\ I[\ Xavier\ A[ V[\ Huynh\
B[ H[\ Vartannian\ D[ V[ De\ Peck\ Jr[\ H[ D[\
Gall\ J[ Le and Moura\ J[ J[\ J[ Biol Chem[\ 0874\
159\ 7831[ "b# Cammack\ R[\ Patil\ D[\ Hatchi!
kian\ E[ C[ and Fernandez\ V[ M[\ Biochem[
Biophys[ Acta\ 0876\ 801\ 87[ "c# Teixeira\ M[\
Moura\ I[\ Xavier\ A[ V[\ Moura\ J[ J[ G[\ Gall\ J[
Le\ Vartannian\ D[ V[ De\ Peck\ Jr[\ H[ D[ and
Huynh\ B[ H[\ J[ Biol[ Chem[\ 0878\ 153\ 05324[
5[ Shukla\ R[\ Mondal\ S[ and Bharadwaj\ P[ K[\
Polyhedron\ 0882\ 01\ 72 and references cited
therein[
6[ Cammack\ R[\ Adv[ Inor`[ Chem[\ 0877\ 21\ 186[
7[ North\ A[ C[\ Philips\ D[ C[ and Mathews\ F[ S[\
Acta Crystallo`raphy\ 0857\ A13\ 240[
8[ Sheldrick\ G[ M[\ SHELXS 75\ A program for
the solution of crystal structure[ University of
Gottingen\ Germany\ "0875#[
H1DSALPTP o}ers comparatively better stabilisation
of the Ni"II# state towards oxidation[ No cathodic
responses was observed for both the complexes up to
−0[4 V[
CONCLUSION
This work illustrates the coordination behaviour
of two interesting hexadentate NSO donor ligands
towards Ni"II#[ Structure of ðNi"DSALPTX#Ł exhibits
the very unusual deployment of the six donor points
of the ligand H1DSALPTX while coordinating to the
Ni"II# acceptor centre[ Only single crystal X!ray
di}raction study could establish such unusual orien!
tation of the donor sites[
09[ Sheldrick\ G[ M[\ SHELXL 82\ A program for
the re_nement of crystal structure[ University of
Gottingen\ Germany\ "0875#[
00[ Cooper\ S[ R[\ Rawle\ S[ C[\ Hartman\ J[ A[ R[\
Hintsa\ E[ J[ and Admans\ G[ A[\ Inor`[ Chem[\
0877\ 16\ 0198[
Acknowled`ements*We are thankful to the National
Di}ractometer Facility "DST#\ Department of Biophysics\
All India Institute of Medical Science\ New Delhi for X!ray
di}raction data collection[ S[ P[ is grateful to C[S[I[R[ for
_nancial support in the form of a Research Associateship[
01[ Pal\ S[\ Mukherjee\ G[ and Poddar\ S[ N[\ Trans[
Met[ Chem[\ 0883\ 08\ 88[
02[ Pal\ S[\ Poddar\ S[ N[ and Mukherjee\ G[\ Trans[
Met[ Chem[\ 0883\ 08\ 338[
REFERENCES
0[ Pal\ S[\ Poddar\ S[ N[ and Mukherjee\ G[\ Poly! 03[ Karmakar\ S[\ Bhanjachoudhury\ S[\ Ray\ D[ and
hedron\ 0882\ 01\ 1354[
Chakraborty\ A[\ Polyhedron\ 0882\ 01\ 180[