Synthesis and characterization of homoleptic and heteroleptic cobalt, nickel, copper, zinc and cadmium compounds with the 2-(tosylamino)-N-[2- (tosylamino)benzylidene]aniline ligand

FULL PAPER

DOI: 10.1002/ejic.201001356

Synthesis and Characterization of Homoleptic and Heteroleptic Cobalt,

Nickel, Copper, Zinc and Cadmium Compounds with the

2-(Tosylamino)-N-[2-(tosylamino)benzylidene]aniline Ligand

Antonio Sousa-Pedrares,^[a]Joaquin A. Viqueira,^[a]Jorge Antelo,^[a]Elena Labisbal,^[a]

Jaime Romero,^[a]Antonio Sousa,^[a]Otaciro R. Nascimento,^[b]and

José A. García-Vázquez*^[a]

Keywords: Copper / Cobalt / Nickel / Zinc / Cadmium / Transition metals / Schiff bases / Structure elucidation / Hydrogen

bonds / Stacking interactions / Electrochemistry

The electrochemical oxidation of anodic metal (cobalt,

nickel, copper, zinc and cadmium) in an acetonitrile solution

of the Schiff-base ligand 2-(tosylamino)-N-[2-(tosylamino)-

benzylidene]aniline (H₂L) afforded the homoleptic com-

pounds [ML]. The addition of 1,1-diphenylphosphanylmeth-

ane (dppm), 2,2Ј-bipyridine (bipy) or 1,10-phenanthroline

(phen) to the electrolytic phase gave the heteroleptic com-

plexes [NiL(dppm)], [ML(bipy)] and [ML(phen)]. The crystal

structures of H₂L (1), [NiL] (2), [CuL] (3), [NiL(dppm)] (4),

[CoL(phen)] (5), [CuL(bipy)] (6) and [Zn(Lphen)] (7) were de-

termined by X-ray diffraction. The homoleptic compounds

[NiL] and [CuL] are mononuclear with a distorted square

planar [MN₃O] geometry with the Schiff base acting as a di-

anionic (N_amideN_amideN_imineO_tosyl) tetradentate ligand. Both

tween a six-membered chelate ring containing the metal and

a phenylic ring of the ligand. In the heteroleptic complex

[NiL(dppm)], the nickel atom is in a distorted tetrahedral

[NiN₃P] environment defined by the imine, two amide nitro-

gen atoms of the L^2–dianionic tridentate ligand and one of

the phosphorus atoms of the dppm molecule. In the other

heteroleptic complexes, [CoL(phen)], [CuL(bipy)] and

[ZnL(phen)], the metal atom is in a five-coordinate environ-

ment defined by the imine, two amide nitrogen atoms of the

dianionic tridentate ligand and the two bipyridine or phen-

anthroline nitrogen atoms. The compounds were charac-

terized by microanalysis, IR and UV/Vis (Co, Ni and Cu com-

plexes) spectroscopy, FAB mass spectrometry and ¹H NMR

([NiL] and Zn and Cd complexes) and EPR spectroscopy (Cu

compounds exhibit an unusual π–π stacking interaction be- complexes).

For the reasons outlined above, and as a result of our

Introduction

continued interest in the chemistry of metal complexes with

amide ligands, we report herein the synthesis of metal(II)

complexes with 2-(tosylamino)-N-[2-(tosylamino)benzyl-

idene]aniline, a molecule that contains two weakly acidic

N–H groups and an imine group (Scheme 1). Owing to the

presence in the ligand of these weakly acidic groups, homo-

leptic complexes were prepared by using an electrochemical

procedure in which the metal was the anode of a cell con-

taining the Schiff-base ligand in acetonitrile solution. The

presence in the electrolytic cell of the Schiff base and co-

The chemistry of metal complexes with amide ligands

has been widely studied, partly due to the use of such com-

pounds as antibacterial drugs in the field of medicine.^[1]In

particular, copper(II)^[2]and zinc(II)^[3]complexes have been

used in the treatment of numerous diseases and carbonic

anhydrase inhibitory properties have been studied for Ni^II

complexes.^[4]However, it is well known that metal complex

formation by the substitution of an amide proton by a

metal ion is not an easy process.^[5]This complexation pro-

cess is facilitated by the presence in the amide groups of

electron-withdrawing substituents, such as a sulfonyl group,

which increases the acidity of the N–H group and makes

deprotonation of the ligand, and thus metal complex for-

mation, easier.^[6]

[a] Departamento de Química Inorgánica, Universidad de Santi-

ago de Compostela,

15782 Santiago de Compostela, Spain

Fax: +34-(9)81-547102

E-mail: josearturo.garcia@usc.es

[b] Instituto de Física de Sao Carlos, Universidade de Sao Paulo,

CP 369, 13560-250 Sao Carlos, SP, Brazil

Supporting information for this article is available on the

WWW under http://dx.doi.org/10.1002/ejic.201001356.

Scheme 1.

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ligands, such as 1,1-diphenylphosphanylmethane, 2,2Ј-bi- standing the interactions that influence the packing arran-

pyridine or 1,10-phenanthroline, allowed the synthesis of gements in the complexes and this topic is discussed in the

heteroleptic compounds in one step. This method has been Supporting Information.

successfully used for the synthesis of metal compounds with

other ligands that contain weak acid groups, such as

thiol,^[7–10]NH^[11–13]or hydroxy groups.^[14–17]

Homoleptic Complexes

The electrochemical oxidation of anodic cobalt, nickel,

copper, zinc or cadmium in a cell containing 2-(tosyl-

amino)-N-[2-(tosylamino)benzylidene]aniline (H₂L) in

acetonitrile gave the complexes [ML]. The complexes were

obtained as crystalline materials by concentration of the

acetonitrile solution by evaporation in air.

Results and Discussion

Synthesis and General Characterization

The analytical data of the products show that the electro-

chemical procedure described can be satisfactorily used to

obtain good yields in the synthesis of complexes of homo-

and heteroleptic cobalt, nickel(II), copper(II), zinc(II) and

cadmium(II) sulfonamide complexes [ML], [NiL(dppm)]

and [MLLЈ] (LЈ = phen or bipy). This method represents a

simple alternative to other standard chemical procedures.

The electrochemical efficiency, defined as mole of metal

dissolved per Faraday of charge, was close to 1 molF^–1for

the copper complexes, which shows that anodic oxidation

leads initially to a Cu^Icompound. However, the analytical

data show that the complex is [CuL] or [CuLLЈ]. This sug-

gests that the ligand oxidizes Cu^Ito Cu^IIin solution as soon

as it is formed.

Structures of [NiL] (2) and [CuL] (3)

The molecular structures of complexes 2 and 3 are shown

in Figure 1 along with the atomic numbering schemes

adopted. Selected bond lengths and angles are given in

Table 1. The two compounds are isostructural and consist

of monomer units. In both complexes the metal atom is

tetracoordinated to two amide nitrogen atoms, the imine

nitrogen atom and one of the oxygen atoms of one of the

tosyl groups of the dianionic tetradentate Schiff base. In

both compounds the coordination polyhedron around the

metal atom is distorted square planar with the amide nitro-

gen atoms in a trans disposition. This distortion is caused

mainly by the small bite angle, 68.20(13)° for [CuL] and

72.59(19)° for [NiL] complexes with a four-membered che-

late ring, and to a lesser extent by other angles involving

five- {85.62(14)° for [CuL] and 86.0(2)° for [NiL]} and six-

membered {92.87(15)° for [CuL] and 94.4(2)° for [NiL]}

chelating ligand rings, which also deviate from the theoreti-

cal value. The square-planar geometry of the metal(II) ions

in both compounds show a tetrahedral distortion. However,

the dihedral angle between the two planes, each en-

compassing the metal and two donor atoms (N–M–N), of

14.85(17)° for [CuL] indicates a higher distortion from the

square-planar geometry than the value of 7.98(22)° for the

[NiL] complex (for a square-planar geometry the value

would be 0° and for a tetrahedral geometry 90°). Thus, this

tetrahedral distortion is more pronounced in the copper

complex. This situation is also apparent because in [CuL]

the copper atom is located –0.141 Å below the mean plane

formed by O(1), N(1), N(2) and N(3), whereas in [NiL] the

nickel is almost in the mean plane (–0.040 Å) that contains

the same donor atoms.

This behaviour has been observed previously in the syn-

thesis of other copper complexes by electrochemical pro-

cedures.^[11,12,14]

For the other metals, the electrochemical efficiency of the

cell was close to 0.50 molF^–1. This fact, along with the evol-

ution of hydrogen at the cathode, is compatible with the

following reaction mechanisms:

In the case of [NiL], the Ni–N_iminebond length of

1.842(4) Å is slightly shorter than the value found in other

complexes containing tetracoordinate nickel(II) and a

Schiff base as ligand [1.860(2)–2.000(3) Å].^[19–23]The Ni–

N_amidebond lengths [1.833(5) and 1.895(4) Å] are signifi-

cantly different to each other. In addition, both bonds are

shorter than the range [2.030(6)–1.905(2) Å] described for

tetracoordinate Ni^IIcomplexes with Schiff bases containing

Structure of the Ligand (H₂L)

The crystal structure of the ligand has been published nitrogen amide donor atoms.^[19–23]The Ni–O_tosylbond

previously.^[18]However, the crystal packing was not de- length of 2.004(4) Å is also shorter than those found in

scribed and this aspect is of great interest in terms of under- hexacoordinate complexes with ligands containing sulfon-

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Eur. J. Inorg. Chem. 2011, 2273–2287

Homoleptic and Heteroleptic Co, Ni, Cu, Zn and Cd Compounds

Figure 1. ORTEP diagram of the molecular structures of [NiL] (left) and [CuL] (right).

Table 1. Selected bond lengths [Å] and angles [°] for [NiL] and [CuL].

M = Ni

M = Cu

M = Ni

M = Cu

M(1)–N(1)

M(1)–N(3)

M(1)–O(3)

N(1)–M(1)–N(2)

N(2)–M(1)–N(3)

N(2)–M(1)–O(1)

1.833(5)

1.895(4)

3.189(4)

94.4(2)

86.0(2)

164.66(17)

1.899(3)

1.935(3)

3.114(3)

92.87(15)

85.62(14)

156.96(14)

M(1)–N(2)

M(1)–O(1)

N(2)–C(14)

N(1)–M(1)–N(3)

N(1)–M(1)–O(1)

N(3)–M(1)–O(1)

1.842(4)

2.004(4)

1.314(6)

177.0(2)

72.59(19)

107.38(18)

1.906(3)

2.203(3)

1.293(5)

177.15(15)

68.20(13)

112.68(13)

amide groups coordinated through one oxygen atom of the of the oxygen atoms of the SO₂groups, apart from that

SO₂group (2.095–2.131 Å),^[24,25]a situation that reflects the directly coordinated to the metal (O1), establish C–H···O

lower coordination number in [NiL]. To the best of our interactions with different C–H groups. These C–H···O in-

knowledge, the Ni–O_tosylbond lengths in tetracoordinate teractions only occur in two dimensions and they give rise

nickel(II) complexes have not previously been estimated, to layers of molecules parallel to the crystallographic ab

which means that comparisons cannot be made with the plane (see Figure S1 in the Supporting Information for

Ni–O_tosylbond length in [NiL].

In the case of [CuL], the Cu–N_amide[1.899(3) and tions in both compounds are given in Table S1.

1.906(3) Å] bond lengths are similar to each other, but they Furthermore, the molecules are arranged in such a way

[NiL]). The parameters for the hydrogen-bonding interac-

are slightly shorter than the usual range (2.088–1.956 Å) along the crystallographic c axis that the planar part of the

found in tetracoordinate copper(II) complexes derived from complex and the 4-toluenesulfonate groups alternate. As

ligands containing tosyl groups.^{[21–23,26–28]}The Cu–N_imineshown in Figure 2 for M = Ni, three π–π stacking interac-

distance [1.935(3) Å] is also slightly shorter than those tions are formed, all of them involving chelate rings, and

found in tetracoordinate complexes with Schiff-base ligands it is reasonable that the metal atom is involved in the π

(ranging from 1.954–1.981 Å).^[23,24,28]Once again, com- delocalization. These interactions are termed “parallel dis-

plexes of tetracoordinate copper with a Cu–O_tosylbond placed” (Janiack^[30]), that is, the two rings are essentially

have not been studied by X-ray diffraction, but the Cu– parallel to one another but are not perfectly aligned. These

O_tosyldistance of 2.203(3) Å in [CuL] is comparable to interactions are strong, as shown by the distances between

those found in pentacoordinate copper complexes contain- centroids, 3.433(3) and 3.466(3) Å for M = Ni and 3.318(2)

ing different substituted N-(2-pyridyl)sulfonamide ligands and 3.422(2) Å for M = Cu (see Table S2 for complete data

[2.209(6)–2.2914(18) Å].^[12]

on the π-stacking interactions).

In both complexes, the bond lengths and angles within

The packing arrangements present in the crystal struc-

the Schiff base are as expected. In particular, the imine C– ture show two types of chemical process that favour mag-

N bond length, 1.314(6) for [NiL] and 1.293(5) Å for [CuL], netic weak exchange interactions between the metal ions,

is consistent with the value of 1.30 Å proposed for a C=N and these are hydrogen-bonding and π–π stacking interac-

bond.^[29]

tions. In the case of the Cu^IIion, the EPR analyses of the

As in the free ligand (see the Supporting Information), solid, powder and single crystal show collapsed lines with

the crystal packing in the complexes [NiL] and [CuL] is anisotropic g values and without hyperfine interactions

mainly due to C–H···O hydrogen-bonding interactions. All (electron spin-nuclear spin), as widely described in ref.^[31]

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tion. In all other cases, the analytical data and the spectro-

scopic studies performed on the resulting products showed

no evidence for the incorporation of the additional co-li-

gand and the homoleptic compound [ML] was formed ex-

clusively.

The heteroleptic metal(II) sulfonamide compounds were

obtained as crystalline solids by concentration of the re-

sulting acetonitrile solutions in air. These complexes were

found to be more soluble than the homoleptic analogues in

chloroform and a range of other chlorinated organic sol-

vents.

Crystal Structure of [NiL(dppm)] (4)

Figure 2. Crystal structure of [NiL] with π–π stacking interactions

between the chelate ring and one of the phenyl rings shown as

dotted lines.

The molecular structure of [NiL(dppm)] (4) is shown in

Figure 3 and selected bond lengths and angles are given in

Table 2. The compound consists of discrete molecules with

the nickel atom coordinated to two amide nitrogen atoms

and the imine atom of the Schiff base, which can be consid-

ered to act as a tridentate dianionic Schiff base. The coordi-

Heteroleptic Complexes

Co-ligands such as 1,1-diphenylphosphanylmethane, nation around the nickel atom is completed by one of the

1,10-phenanthroline or 2,2Ј-bipyridine were added to the phosphorus atoms of a 1,1-diphenylphosphanylmethane

electrochemical cell with the intention of incorporating (dppm) molecule, which acts as a monodentate ligand. The

them as co-ligands for metal coordination. The electro- other phosphorus atom of dppm is not coordinated to the

chemical oxidation of the appropriate metal in a solution metal. A weak interaction between the nickel atom and one

of 2-(tosylamino)-N-[2-(tosylamino)benzylidene]aniline and oxygen atom (O1) from one sulfonyl group is also observed.

an equimolar amount of 2,2Ј-bipyridine or 1,10-phenan- This weak Ni(1)–O(1) interaction causes the O(1)–S(1)–

throline in acetonitrile gave selectively the complexes N(1) angle [100.6(2)°] to be smaller than one would expect

[ML(phen)] or [ML(bipy)], which shows that the co-ligand for a regular tetrahedron.

had been incorporated into the complex. However, when

The geometry around the nickel atom is best described

the co-ligand 1,1-diphenylphosphanylmethane (dppm) was as distorted tetrahedral [NiN₃P] as the dihedral angle be-

added to the electrochemical cell, only in the case of the tween the P(1)–Ni(1)–N(1) and N(3)–Ni(1)–N(2) planes is

nickel complex was the co-ligand incorporated into the 81.84(12)°. This distortion is shown by the angles between

metal coordination sphere. The complex isolated in this donor atoms and nickel atoms, which vary from 82.96(15)

case was [NiL(dppm)] (4), as confirmed by X-ray diffrac- to 151.19(14)°. The widest angle is that between nickel and

Figure 3. ORTEP diagram of the molecular structure of [NiL(dppm)].

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Eur. J. Inorg. Chem. 2011, 2273–2287

Homoleptic and Heteroleptic Co, Ni, Cu, Zn and Cd Compounds

Table 2. Selected bond lengths [Å] and angles [°] for [NiL(dppm)].

complexes that contain donor oxygen tosyl ligands. How-

ever, the distance is shorter than the sum of the

van der Waals radii of these elements^[35]and comparable to

the distances in other tetracoordinate nickel complexes

characterized by weak intramolecular Ni–O_tosylinterac-

tions.^[21,36]

The phenyl rings of the ligand are essentially planar, with

a maximum deviation of less than 0.02 Å. The P and the S

atoms are practically on the plane of the ring to which they

are bonded.

The crystal packing in this compound is closely related

to that of the homoleptic nickel complex discussed above,

[NiL]. As in the case of [NiL], all of the oxygen atoms of

the SO₂groups are involved in C–H···O interactions with

different C–H groups. These interactions also only occur in

two dimensions, giving rise to layers parallel to the crystal-

lographic ab plane. The data for these interactions are given

in Table S1. The fundamental difference between the two

compounds under discussion is evident if we consider the

crystallographic c axis. The disposition of the complexes in

this direction is similar to that in the homoleptic complex

with the 4-toluenesulfonate groups and dppm units facing

each other in an alternate manner. In the case of the homo-

leptic complex, the absence of co-ligands enables π–π stack-

ing interactions between the planar parts of the two com-

plexes, whereas in this case the presence of dppm ligands at

this face does not allow such interactions to form.

Ni(1)–N(1)

Ni(1)–N(2)

Ni(1)–O(1)

N(2)–C(14)

N(1)–Ni(1)–N(3) 151.19(14)

N(3)–Ni(1)–N(2) 82.96(15)

N(3)–Ni(1)–P(1) 99.71(10)

N(1)–Ni(1)–O(1) 63.64(12)

N(2)–Ni(1)–O(1) 145.22(12)

N(1)–Ni(1)–O(3) 129.61(12)

N(2)–Ni(1)–O(3) 135.17(12)

O(1)–Ni(1)–O(3) 66.04(9)

1.951(3)

1.968(3)

2.434(3)

1.273(5)

Ni(1)–N(3)

Ni(1)–P(1)

Ni(1)–O(3)

1.964(3)

2.3287(13)

3.054(3)

N(1)–Ni(1)–N(2) 90.82(15)

N(1)–Ni(1)–P(1) 109.05(11)

N(2)–Ni(1)–P(1) 98.95(11)

N(3)–Ni(1)–O(1) 107.70(12)

P(1)–Ni(1)–O(1) 111.16(8)

N(3)–Ni(1)–O(3) 52.39(11)

P(1)–Ni(1)–O(3) 86.33(7)

the amide nitrogen atoms and this seems to be the result of

an attempt to minimize the steric hindrance between the

tosyl groups.^[19–23]

The Ni–N_amidebond lengths [1.951(3) and 1.964(3) Å]

are similar to each other but slightly greater than the values

found in [NiL]. However, these values are within the usual

range (1.905–2.030 Å) found in complexes with tetracoordi-

nate nickel(II) and ligands containing tosyl groups. The Ni–

N_iminebond length in [NiL(dppm)] [1.968(3) Å] is also

longer than that observed in the aforementioned complex

[NiL], but it is similar to those found in tetracoordinate

nickel(II) complexes with Schiff-base ligands, which have

values in the range 1.860(2)–2.000(3) Å.^[19–23]The Ni–P

bond length [2.3287(13) Å] does not differ significantly

from the value observed in the tetracoordinate complex di-

bromo[N-2(diisopropylphosphanyl)benzyl]-N,N-dimethyl-

aminonickel(II),^[32]but is greater than those found in other

tetracoordinate nickel(II) complexes in which phosphorus Crystal Structures of [CoL(phen)] (5) and [ZnL(phen)] (7)

is a donor atom (2.168–2.199 Å).^[33,34]

As in the complexes [NiL] and [CuL], the Schiff-base li-

Complexes 5 and 7 are isostructural. [CoL(phen)] (5) is

gand is again orientated in such a way that one of the oxy- shown in Figure 4 along with the atomic numbering scheme

gen atoms from a tosyl group is close to the nickel atom adopted (molecular structures of 5 and 7 can be viewed in

[distance Ni(1)–O(1) 2.434(3) Å]. This value is higher than Figures S2 and S3). Selected bond lengths and angles for

those observed in the complex [NiL] and in other nickel both compounds are listed in Table 3.

Figure 4. Crystal packing diagram of [CoL(phen)]. Intermolecular π–π stacking interactions between phenanthroline rings are represented

by dotted lines.

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Table 3. Selected bond lengths [Å] and angles [°] for [CoL(phen)] and [ZnL(phen)].

M = Co

M = Zn

M = Co

M(1)–N(3)

M(1)–N(4)

M(1)–N(5)

N(1)–M(1)–N(3)

N(3)–M(1)–N(2)

N(3)–M(1)–N(4)

N(1)–M(1)–N(5)

N(2)–M(1)–N(5)

2.034(6)

2.133(6)

2.156(6)

138.1(3)

77.7(3)

111.3(2)

104.1(2)

86.6(2)

1.988(10)

2.107(11)

2.174(11)

134.8(4)

77.0(4)

112.3(4)

105.2(4)

86.8(4)

M(1)–N(1)

M(1)–N(2)

N(2)–C(14)

N(1)–M(1)–N(2)

N(1)–M(1)–N(4)

N(2)–M(1)–N(4)

N(3)–M(1)–N(5)

N(4)–M(1)–N(5)

1.994(6)

2.132(6)

1.242(10)

84.7(3)

1.991(10)

2.123(12)

1.258(16)

85.7(4)

95.5(2)

96.2(4)

164.4(2)

112.2(3)

78.2(2)

162.9(4)

114.9(4)

76.3(4)

The compounds consist of discrete molecules that con- N_iminebond length is similar to those found in the afore-

tain a pentacoordinate metal atom. The geometrical param- mentioned complex^[43,44]and in other pentacoordinate

eter τ [τ = (β – α)/60, in which α and β are the N(2)–M(1)– complexes of Zn with Schiff bases.^[45,46]The Zn–N bond

N(4) and N(3)–M(1)–N(1) bond angles, respectively]^[37]has lengths formed with the phenanthroline ligand [2.107(11)

a value of 0.44 for [CoL(phen)] and 0.47 for [ZnL(phen)]. and 2.174(11) Å] are similar to those found in other penta-

This suggests that the complexes have a geometry interme- coordinate phenanthroline complexes.^[47–50]

diate between a square pyramid (τ = 0) and a trigonal bi-

In these cases the interactions largely responsible for the

pyramid (τ = 1). The environment around the cobalt metal crystal packing are the C–H···O hydrogen-bonding interac-

is formed by one of the 1,10-phenanthroline nitrogen atoms, tions established between the oxygen atoms of the SO₂

the imine nitrogen atom and the two deprotonated amide groups of the ligands (H₂L) and different C–H groups, with

nitrogen atoms of the two 4-toluenesulfonamide groups, π–π stacking interactions also evident between the nitrogen-

which occupy the basal sites, with the other 1,10-phenan- ated co-ligands. The C–H···O interactions are similar to

throline nitrogen atom in the apical site. In this arrange- those already discussed for the free ligand and for the other

ment, N(1) and N(3) are 0.41 and 0.45 Å (0.47 and 0.46 Å complexes, although in these cases the interactions are es-

for the zinc complex) above the best least-squares plane of tablished in three dimensions (see data in Table S1). On the

N(1)–N(2)–N(3)–N(4), and N(2) and N(4) are –0.52 and other hand, as mentioned above, the nitrogenated co-li-

–0.34 Å below the plane (–0.57 and –0.37 Å for zinc com- gands, 1,10-phenanthroline, are involved in π-stacking in-

plex). The cobalt and zinc atoms are 0.16 Å out of these teractions with each other. These co-ligands are essentially

planes. The low value of one of the chelate angles [N(3)– planar and are arranged parallel to the crystallographic ac

M(1)–N(2) 77.7(3)° for the cobalt complex and 77.0(4)° for plane. The π–π stacking interactions are “parallel dis-

the Zn complex] and the small bite angle of the phen ligand placed” (see data in Table S2) and propagate along the crys-

[78.2(2)° for Co and 76.3(4)° for Zn] are significantly dif- tallographic b axis (see Figure 4 for M = Co). The displace-

ferent to those expected for a regular geometry and this ment of the rings is represented in Scheme 2, which shows

deviation is the main source of the distortion.

a view of the interaction along the b axis. Analysis of the

The two Co–N_amidebond lengths in the complex [CoL- centroid–centroid distances shows that the strongest inter-

(phen)] are similar [1.994(6) and 2.034(6) Å] and not very actions are established between the central ring of one co-

different to those observed in other amide complexes of ligand and one of the lateral rings of the other co-ligand

Co^IIwith the same coordination number around the metal [3.605(5) Å for M = Co and 3.631(8) Å for M = Zn].

atom.^[38]Similarly, the Co–N_iminebond length of 2.132(6) Å

is in the range found for other pentacoordinate cobalt(II)

complexes with Schiff bases.^[38,39]The bond lengths between

the cobalt atom and the two nitrogen atoms from the 1,10-

phenanthroline molecule [2.133(6) and 2.156(6) Å] are very

similar and can be considered as normal and consistent

with those found in other pentacoordinate cobalt com-

plexes that contain 1,10-phenanthroline as a chelating li-

gand.^[40–42]

Scheme 2. Overlap of the phenanthroline rings of the neighbouring

molecules in [ML(phen)] (M = Co, Zn) along the b axis.

The bond lengths around the zinc atom are similar to

those reported for other pentacoordinate complexes with

the same donor atoms. Thus, the Zn–N_amidebond lengths

[1.988(10) and 1.991(10) Å], although shorter than those in

Unfortunately, good quality crystals of [CuL(phen)]

bis{1-[(4-methylphenyl)sulfonamido]-2-[(2-pyridylmethylene)- could not be obtained, with only a fine powder isolated.

amino]benzene}zinc(II) [2.094(4) and 2.087(4) Å],^[43]are of However, one would expect a very similar crystal structure

the same order as the values of 2.06(7) and 2.017(6) Å and, in this case, the EPR signal was similar to that of the

found for Zn–N_amidein the pentacoordinate compound other Cu^IIcomplexes, that is, weak exchange effects with

(2,6-bis{1-[2-(tosylamino)phenylimino]ethyl}pyridine)zinc- collapsed lines without hyperfine interactions (electron

(II).^[44]In addition, the value of 2.123(12) Å for the Zn– spin–nuclear spin).

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Homoleptic and Heteroleptic Co, Ni, Cu, Zn and Cd Compounds

Crystal Structure of [CuL(bipy)] (6)

[2.290(4) Å]. The shorter Cu–N_bipybond length can be con-

sidered as normal and is similar to the bond lengths found

in other five-coordinate copper(II) complexes with biden-

tate 2,2Ј-bipyridine ligands; 2.002(4) Å in di-μ-hydroxo-

bis[(2,2Ј-bipyridine)(trifluoromethanesulfonato-O)copper-

(II)]^[53]and 2.0037(18) Å in 2,2Ј-bipyridine-{2-[2Ј-(N-tosyl-

amino)benzylideneamino]phenolato}copper(II).^[52]How-

ever, the bond length of 2.290(4) Å is unusually high and

similar to the longest Cu–N distance found in [Cu-

(phen)₃]²⁺, a compound with a very pronounced Jahn–

Teller distortion.^[54]Similar behaviour has been found in

the cases of 1,10-phenanthroline{2-[2-(oxyphenyl)imino-

methyl]phenolato}copper(II),^[55]1,10-phenanthroline-{N-

[(2-oxophenyl)methylidene]-N-4-toluenesulfonylbenzene-

1,2-diaminato}copper(II)^[56]and 2,2Ј-bipyridine-{2-[2Ј-(N-

tosylamino)benzylideneamino]phenolato}copper(II).^[52]The

Cu–N_amidebond lengths [2.014(5) and 2.027(4) Å] are not

different to those found in other pentacoordinate copper(II)

complexes,^[57]for example, 2.041(5) and 2.031(5) Å in

[CuL₂dmf], with HL representing N-(p-tolylsulfonyl)-o-

phenylenediamine,^[58]or 2.003(2) and 2.044(3) Å in the

above-mentioned sulfonamide complexes.^[52,56]

The molecular structure of [CuL(bipy)] is shown in Fig-

ure 5 along with the atom numbering system used. Selected

bond lengths and angles are listed in Table 4.

The crystal packing in this compound is very similar to

that described above for other heteroleptic complexes with

1,10-phenanthroline ligands (compounds 5 and 7). Thus, all

the oxygen atoms of the SO₂groups are involved in C–

H···O interactions that extend in three dimensions, al-

though they are weaker than in the other complexes re-

ported (see data in Table S1). The bipyridine co-ligands are

also oriented parallel to the crystallographic ac plane, lead-

ing to π–π stacking interactions along the b axis between

one ring of the co-ligand and a symmetry equivalent of the

other ring, as shown in Figure 6. These interactions are also

“parallel displaced” (see data in Table S2) and quite strong

Figure 5. ORTEP diagram of the molecular structure of [CuL-

(bipy)].

Table 4. Selected bond lengths [Å] and angles [°] for [CuL(bipy)].

Cu(1)–N(2)

Cu(1)–N(1)

1.987(5)

2.027(4)

Cu(1)–N(3)

Cu(1)–N(4)

2.014(5)

2.032(4)

Cu(1)–N(5)

2.290(4)

N(2)–C(14)

1.273(6)

N(2)–Cu(1)–N(3)

N(3)–Cu(1)–N(1)

N(3)–Cu(1)–N(4)

N(2)–Cu(1)–N(5)

N(1)–Cu(1)–N(5)

81.64(19)

144.29(18)

101.66(18)

87.22(18)

110.65(16)

N(2)–Cu(1)–N(1)

N(2)–Cu(1)–N(4)

N(1)–Cu(1)–N(4)

N(3)–Cu(1)–N(5)

N(4)–Cu(1)–N(5)

86.92(18)

164.13(18)

98.50(18)

102.48(17)

76.91(19)

N(5)–C(33)–C(32) 116.7(5)

N(5)–C(37)–C(36) 124.2(5)

The complex consists of monomer units in which a

pentacoordinate [CuN₅] copper atom is bound to two

amide nitrogen atoms and the imine nitrogen atom of the

tridentate dianionic Schiff-base ligand. A neutral 2,2Ј-bi-

pyridine molecule acting as an (N,N) bidentate chelating

donor completes the coordination sphere of the metal. Con-

sequently, the environment around the copper atom may be

described as a distorted square pyramid (τ = 0.33) with one

of the nitrogen [N(5)] atoms of the 2,2Ј-bipyridine molecule

as the apical atom. The copper atom and the basal donor

atoms are coplanar within the limits of experimental accu-

racy.

The Cu–N_iminebond length [1.987(5) Å] is similar to

those found in other five-coordinate copper compounds, for

example, in bis(dimethylaminoethylsalicylaldiminato)cop-

per(II)^[51](mean value of 1.946 Å) or 2,2Ј-bipyridine-{2-[2Ј-

(N-tosylamino)benzylideneamino]phenolato}copper(II)^[52]

[1.973(17) Å]. The Cu–N_bipybond lengths are different with

Figure 6. Crystal packing diagram of [CuL(bipy)]. Intermolecular

π–π stacking interactions between bipyridine rings are represented

the basal bond [2.032(4) Å] shorter than the apical bond by dotted lines.

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[centroid–centroid distance 3.552(7) Å]. The displacement ³B₁Ǟ³A₂transitions, respectively. These data are consistent

of the rings can be seen in Scheme 3, which shows a view with a distorted square-pyramidal geometry for these com-

of the interaction along the b axis.

plexes.

The diffuse reflectance spectrum of [CuL] shows a broad

band at around 17800 cm^–1, in agreement with the values

reported for square-planar copper(II) complexes. The elec-

tronic reflectance spectra of [CuL(bipy)] and [CuL(phen)]

contain two broad bands in the ranges 11470–13270 and

15150–15200 cm^–1, in agreement with a square-pyramidal

environment of a CuN₅chromophore. This geometry was

identified in the X-ray structure determination of [CuL-

(bipy)] (6).

Scheme 3. A view along the b axis showing the overlap between

bipyridine rings of two neighbouring molecules of [CuL(bipy)].

The IR spectra of these complexes do not show the band

attributed to ν(N–H), which in the ligand appears at

3297 cm^–1, confirming the loss of the amide protons during

the electrolysis and showing that the ligand is in the dian-

ionic amidate form in the complex. On the other hand, the

band attributable to ν(C=N) of the imine group is shifted

to a lower frequency on going from the free ligand

As far as the EPR spectrum of [CuL(bipy)] is concerned,

the results were similar to those obtained for other Cu^II

complexes.

Spectroscopic Studies

The cobalt(II), nickel(II) and copper(II) complexes were (1618 cm^–1) to the complexes (1593–1612 cm^–1) as a result

also studied by electronic spectroscopy in the solid state.^[59]of coordination of the imine nitrogen to the metal. These

Compound [CoL] shows a multicomponent band at 78130 observations suggest that the imine nitrogen and two amide

and 9025 cm^–1, which has been assigned to A₂Ǟ⁴T₁(F), nitrogen atoms of the dianionic Schiff base are coordinated

4

and another at 17800 cm^–1due to ⁴A₂Ǟ⁴T₁(P), both of to the metal atom. In addition, the two bands in the ranges

which are the result of a distorted tetrahedral environment. 1340–1325 and 1115–1143 cm^–1, assignable to the asymmet-

The spectra of the heteroleptic complexes of cobalt(II), with ric and symmetric modes of the SO₂group, respectively, are

signals between 22000 and 5000 cm^–1, are similar to each shifted to significantly lower frequencies, with this shift be-

other but differ from that of the [CoL] complex. The spec- ing more marked in the complexes [NiL] and [CuL]. This

tra of these complexes show the characteristic features of behaviour can be considered as evidence of an interaction

five-coordinate cobalt(II) ions with a distorted square-py- between the oxygen atom of the sulfonyl group and the

ramidal stereochemistry. Thus, the complexes [CoL(bipy)] metal atom. This conclusion is confirmed by the X-ray

and [CoL(phen)] give rise to bands at around 7500 and structures of 2 and 3.

7600, 11180 and 11140, 16835 and 17200, and 22030 and

The IR spectra of the heteroleptic complexes show sim-

22030 cm^–1, respectively, and these have been assigned to ilar bands to those described above for the homoleptic com-

⁴E_g(⁴T_1g)Ǟ⁴E_g(⁴T_2g), ⁴E_g(⁴T_1g)ǞB_1g, ⁴E_g(⁴T_1g)Ǟ⁴Eg- plexes and these are characteristic of a coordinated Schiff-

(⁴T_1g) and ⁴E_g[⁴T_1g(P)]ǞA_2g[⁴T_1g(P)] transitions, respec- base ligand. Additional bands are also observed at around

tively, in a square-pyramidal geometry. This environment 758 and 735, and 725, 845 and 1510 cm^–1, and 1470, 1125,

was found in the X-ray structure determination of [CoL- 785, 745 and 699 cm^–1, which are typical of coordinated

(phen)] (5).

2,2Ј-bipyridine,^[60]1,10-phenanthroline^{[60 61]}and dppm,^[62]

,

The solid-state electronic spectrum of the complex [NiL] respectively.

shows three bands at 10820, 15780 and 23500 cm^–1, which

can be attributed to the ¹A_1gǞ¹A_2g, ¹A_1gǞ¹B_1gand

¹A_1gǞ¹E_1gtransitions, respectively. These are characteris-

tic of nickel(II) compounds in a square-planar environment.

NMR Spectra

The diffuse reflectance spectrum of [NiL(dppm)] exhibits

The diamagnetic nature of the complex [NiL] allowed us

two d–d bands well within the range of tetrahedral com- to carry out an NMR study in solution. The room-tempera-

plexes of nickel(II) (ca. 7200 and 15600 cm^–1), which can be ture ¹H NMR spectra of this nickel complex and of the zinc

assigned to the ³T₁(F)Ǟ³A₂and ³T₁(F)Ǟ³T₁(P) transi- and cadmium complexes show that the singlets attributable

tions, respectively. The solid-state electronic spectra of the to the NH hydrogens, which appear in the free ligand at δ

mixed nickel complexes [NiL(bipy)] and [NiL(phen)] are = 10.80 and 9.85 ppm, are not present in the complexes,

consistent with a pentacoordinate environment around the again reinforcing the conclusion from the IR data that the

nickel atom. The bands observed in these spectra cannot be ligands are coordinated to the metal in the dianionic form

unequivocally assigned to specific electronic transitions, but as a result of deprotonation of the ligand. Furthermore, the

the bands in the visible region at 16200, 16700 and 22800, signal of the azomethine hydrogen atom is shifted to a

3

22030 cm^–1have been assigned to B₁Ǟ³E and B₁Ǟ³A₂, lower field, around 0.3–0.5 ppm, upon complexation. This

³E(P). The bands in the near-IR region at about 8830, 8790 behaviour is a consequence of the coordination of the imine

and 10640, 11040 cm^–1have been assigned to B₁Ǟ³E and nitrogen to the metal. In the spectra of the heteroleptic

3

³B₁Ǟ³B₂and the shoulders at 12500 and 12400 cm^–1to complexes [CdL(bipy)] and [CdL(phen)], two low intensity

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Eur. J. Inorg. Chem. 2011, 2273–2287

Homoleptic and Heteroleptic Co, Ni, Cu, Zn and Cd Compounds

peaks are also observed around this signal and these corre- EPR Spectra

spond to coupling of the imine nitrogen with the ¹¹³Cd iso-

tope [³J(¹H–¹¹³Cd) = 17 Hz]. This coupling provides evi-

dence for the coordination of the ligand to the metal

through the imine nitrogen. The multiplet resonances in the

aromatic region (δ = 8.0–6.79 ppm) and also the signals cor-

responding to the methyl groups (δ = 2.40–2.20 ppm) ap-

pear slightly shifted with respect to those in the free ligand.

This change is due to the coordination of the ligand. In

The EPR spectra of the Cu compounds [CuL] (3), [CuL-

(bipy)] (6) and [CuL(phen)] are shown in Figures 7, 8 and

9, respectively, in which (a) are the spectra of powder sam-

ples and (b) are the spectra of the frozen solution samples.

All of the powder samples gave rise to EPR spectra without

resolution of the hyperfine structure of the Cu nuclear spin

(I = 3/2). In accord with the X-ray structure results, which

show intermolecular interactions between Cu^IIions, such as

hydrogen bonding and π–π stacking, the EPR results for the

powder samples are in agreement with the weak exchange

interaction that collapses hyperfine lines, with anisotropic g

values. This phenomenon is very well-studied in Cu^IIamino

acids, dipeptides and other molecular compounds.^[31,65–71]

When the samples were diluted (low concentration) in ap-

propriate solvents, the frozen EPR spectra showed hyper-

fine structure from the Cu nuclear spin (I = 3/2), which

indicates paramagnetic dilution. The samples of [CuL] (3)

and [CuL(bipy)] (6) as frozen solutions show two EPR com-

ponents, one similar to the powder spectrum and another

as a diluted paramagnetic compound. These results suggest

that these two compounds have low solubility. Simulation

using the EasySpin^[72]program gave the EPR parameters

shown in Table 5. The EPR parameters are compatible with a

d_x₂_–y₂orbital describing the unpaired electron with a small

rhombic distortion (g_x϶ g_y). However, the second compo-

1

addition, in the H NMR spectra of the heteroleptic com-

plexes [ML(phen)] (M = Zn and Cd) the signals of the 1,10-

phenanthroline can be distinguished at low field from those

due to the aromatic sulfonamide ligand. In these cases the

signals attributable to the 2,9- and 3,8-protons of 1,10-

phenanthroline (between δ = 9.32–9.14 and δ = 8.13–

8.30 ppm, respectively) experience a small downfield shift

with respect to the corresponding signals in the free ligand.

This shift provides evidence for the coordination of the

1,10-phenanthroline molecule.^[63]The room-temperature ¹H

NMR spectra of [ML(bipy)] (M = Zn, Cd) show signals

that can be assigned to the hydrogen atoms of 2,2Ј-bipyr-

idine in addition to the signals corresponding to the hydro-

gen atoms of the deprotonated sulfonamide ligands. The

downfield shift of the signal attributable to the 3,3Ј protons

(δ = 8.04–8.11 ppm) and the upfield shift of the signal for

the 6,6Ј-protons (δ = 8.98–8.79 ppm) provide evidence to

support the coordination of the 2,2Ј-bipyridine ligand.^[64]

Figure 7. Experimental EPR spectra of the complex [CuL] (3):

(a) powder sample (solid line) and (b) frozen solution sample (solid

line) with spectral simulations (broken lines) obtained by using the

EasySpin programme.^[72]

Figure 8. Experimental EPR spectra of the complex [CuL(bipy)]

(6): (a) powder sample (solid line) and (b) frozen solution sample

(solid line) with spectral simulations (broken lines) obtained by

using the EasySpin programme.^[72]

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Conclusions

In this paper the one-pot synthesis of several new metal

complexes is reported. The highly pure isolated compounds

were analysed spectroscopically and, when possible, by sin-

gle-crystal X-ray diffraction. The synthesis involved an elec-

trochemical procedure. Homoleptic complexes [ML] were

obtained by oxidation of a metal anode in a cell containing

the Schiff base (H₂L), whereas heteroleptic complexes

[MLLЈ] were obtained by adding a co-ligand such as 1,1-

diphenylphosphanylmethane, 2,2Ј-bipiridine or 1,10-phen-

hantroline to the reaction cell. In the [ML] homoleptic com-

plexes the Schiff base acts as a dianionic tetradentate ligand

whereas in the [MLLЈ] heteroleptic complexes the Schiff

base behaves as a dianionic tridentate ligand. X-ray analysis

of the crystal structures revealed some interesting structural

features regarding the intermolecular interactions: com-

pounds 2 and 3 exhibit two unusual and identical π–π

stacking interactions between one phenyl ring and one

metal-containing chelate ring.

Experimental Section

General: Cobalt, nickel, copper, zinc and cadmium (Aldrich) were

used as plates (ca. 2ϫ2 cm). All other reagents, including acetoni-

trile, 2,2Ј-bipyridine, 1,10-phenanthroline and 1,1-diphenylphos-

phanylmethane, were commercial products and were used as sup-

plied. N-Tosyl-1,2-diaminobenzene and 2-(tosylamino)benzalde-

hyde were synthesized according to previously reported procedures.

Figure 9. Experimental EPR spectra of the complex [CuL(phen)]:

(a) powder sample (solid line) and (b) frozen solution sample (solid

line) with spectral simulations (broken lines) obtained by using the

EasySpin programme.^[72]

Physical Measurements: The C, N, H and S contents of the com-

pounds were determined with a Perkin–Elmer 240B microanalyser.

IR spectra were recorded as KBr mulls with a Bruker IFS-66V

1

spectrophotometer. The H NMR spectrum of the ligand was re-

corded with a Bruker WM 350 spectrometer using [D₆]DMSO or

CDCl₃as solvent. The chemical shifts were recorded against TMS

as internal standard. FAB mass spectra were recorded with a

Micromass Autospec instrument using 3-nitrobenzyl alcohol (3-

NBA) as the matrix material. Solid-state electronic spectra were

recorded with a Shimadzu UV 3101 PC spectrophotometer. EPR

measurements were recorded with a CW-X-band EMX Bruker

spectrometer equipped with a liquid N₂accessory for the three Cu

compounds {[CuL] (3), [CuL(bipy)] (6) and [CuL(phen)]} on pow-

der and frozen solutions. Powder samples of the two first com-

pounds were obtained by grinding microcrystals and the third sam-

nent of diluted [CuL] (3) and [CuL(bipy)] (6) presents a

stronger rhombicity, which suggests a possible steric distor-

tion induced by the action of solvent. [CuL] (3) and [CuL-

(bipy)] (6) gave good single crystals and the detailed

measurement of the EPR spectra, as a function of magnetic

field orientation relative to the single crystal axes, is in pro-

gress to obtain information concerning the weak exchange

interaction and the role of the interactions involving hydro-

gen-bonding and ring-stacking, as discussed in the crystal-

lography section.

Table 5. EPR Parameters obtained by spectral simulation.^[a]

Physical

state

EPR

parameters

[CuL] (3)

[CuL(bipy)] (6)

[CuL(phen)]

x

y

z

x

y

z

x

y

z

Solid

g

2.0500

63.0

2.0685

63.0

2.2095

150.0

2.0721

60.0

2.0734

60.0

2.2230

480.0

2.0710

40.0

2.0940

145.0

2.2380

345.0

Lw [MHz]

Frozen

solution

g₁

2.0550

97.2

155

2.0307

49.1

2.1200

83.4

160

2.0890

127.6

2.2600

515.3

170

2.2275

823.0

2.0525

91.6

235

2.0570

49.0

2.1124

92.9

235

2.1800

49.0

2.2820

425.6

235

2.1114

49.0

2.0475

108.4

180

–

2.0642

108.4

180

–

2.2535

472.3

180

––

A₁[MHz]

Lw₁[MHz]

g₂

Lw₂[MHz]

–

[a] g₁and g₂correspond to the two spectral components existent in frozen solution. Lw is line width.

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Eur. J. Inorg. Chem. 2011, 2273–2287

Homoleptic and Heteroleptic Co, Ni, Cu, Zn and Cd Compounds

ple was precipitated. Measurement conditions: microwave fre-

quency 9.4340 GHz, modulation amplitude 0.4 mT, time constant

20.48 ms, time conversion 81.92 ms, solid sample room tempera-

ture, frozen solution 120 K.

1180 (w), 1141 (vs), 1087 (s), 1018 (w), 956 (m), 888 (m), 840 (m),

810 (m), 762 (m), 734 (w), 709 (w), 664 (m), 589 (w) cm^–1. MS

(FAB): m/z = 733 [CoL(bipy)]⁺, 576 [CoL]⁺, 422 [CoL – Ts]⁺, 267

[CoL – 2Ts]⁺. C₃₇H₃₁N₅O₄S₂Co (732.74): C 60.65, N 9.56, H 4.26,

S 8.75; found: C 60.44, N 8.95, H 4.05, S 8.64.

Preparation of 2-(Tosylamino)-N-[2-(tosylamino)benzylidene]aniline

(H₂L): The Schiff base was prepared by heating an ethanolic solu-

tion of equimolar amounts of 2-(tosylamino)benzaldehyde (0.95 g,

10 mmol) and N-tosyl-1,2-diaminobenzene (2.63 g, 10 mmol) at re-

flux. The water produced in the reaction was removed by using a

Dean–Stark trap and the resulting solution was concentrated. The

resulting yellow crystals, which were suitable for X-ray studies, were

filtered off, washed with diethyl ether and dried under vacuum;

[CoL(phen)]: A solution of the ligand (0.150 g, 0.29 mmol) and

1,10-phenanthroline (0.057 g, 0.29 mmol) in acetonitrile (50 cm³)

was electrolysed at 8 V and 10 mA for 1.5 h and 17 mg of cobalt

metal was dissolved from the anode, E_f= 0.51 molF^–1. Air-concen-

tration of the mother liquor gave brown crystals of [CoL(phen)]

suitable for X-ray studies. IR (KBr): ν = 1608 (m), 1594 (m), 1554

˜

(w), 1516 (m), 1495 (w), 1477 (m), 1423 (m), 1384 (w), 1297 (m),

1272 (m), 1261 (s), 1180 (w), 1141 (vs), 1087 (s), 956 (s), 890 (w),

851 (m), 809 (w), 726 (m), 663 (s), 589 (w), 550 (s) cm^–1. MS (FAB):

m/z = 757 [CoL(phen)]⁺, 602 [CoL(phen) – Ts]⁺, 576 [CoL]⁺, 422

[CoL – Ts]⁺. C₃₉H₃₁CoN₅O₄S₂(756.76): calcd. C 61.90, N 9.25, H

4.13, S 8.47; found C 61.87, N 9.55, H 4.14, S 8.38.

yield 70%. IR (KBr): ν = 3298 (m), 2924 (w), 1615 (s), 1596 (m),

˜

1573 (m), 1510 (m), 1483 (s), 1391 (m), 1335 (vs), 1296 (s), 1209

(m), 1184 (m), 1169 (vs), 1153 (vs), 1120 (m), 1090 (s), 952 (m),

887 (m), 818 (s), 760 (vs), 674 (vs), 662 (vs), 574 (s), 541 (vs) cm^–1.

¹H NMR ([D₆]DMSO): δ = 11.44 [s, 1 H, NH (amide-Ph-C)], 9.63

[s, 1 H, NH (amide-Ph-N)], 8.27 (s, 1 H, HC=N), 7.78–6.86 (m, 16

H, aromatic), 2.28 (s, 3 H, CH₃), 2.21 (s, 3 H, CH₃) ppm. ¹H NMR

(CDCl₃): δ = 10.80 [s, 1 H, NH (amide-Ph-C)], 9.85 [s, 1 H, NH

(amide-Ph-N)], 8.20 (s, 1 H, HC=N), 7.77–7.12 (m, 16 H, aro-

matic), 2.35 (s, 3 H, CH₃), 2.15 (s, 3 H, CH₃) ppm. MS (FAB): m/z

= 519 [H₂L]⁺. C₂₇H₂₅N₃O₄S₂(519.63): calcd. C 62.41, H 4.85, N

8.09, S 12.34; found C 61.98, H 4.77, N 8.05, S 11.89.

[NiL]: A solution of the ligand H₂L (0.199 g, 0.38 mmol) in aceto-

nitrile (50 cm³) was electrolysed at 11 V and 10 mA for 2 h and

22.1 mg of nickel was dissolved from the anode, E_f= 0.50 molF^–1.

The reaction mixture was concentrated and [NiL] was obtained as

a crystalline brown solid suitable for X-ray studies. IR (KBr): ν =

˜

1598 (s), 1550 (w), 1475 (s), 1445 (w), 1401 (m), 1306 (s), 1256 (s),

1238 (m), 1137 (vs), 1118 (s), 1088 (vs), 971 (m), 901 (w), 847 (w),

811 (m), 754 (vw), 663 (s), 563 (s) cm^–1. NMR (CDCl₃): δ = 8.60

(s, 1 H, CH=N), 8.00–6.86 (m, 28 H, aromatic), 2.40 (s, 3 H, CH₃),

2.22 (s, 3 H, CH₃) ppm. MS (FAB): m/z = 576 [NiL]⁺, 421 [NiL –

Ts]⁺, 266 [NiL – 2Ts]⁺. C₂₇H₂₃N₃NiO₄S₂(576.33): calcd. C 56.27,

N 7.29, H 4.02, S 11.13; found C 55.52, N 6.65, H 4.64, S 10.66.

Electrochemical Synthesis: The complexes were prepared by follow-

ing a previously reported electrochemical procedure.^[7]The cell con-

sisted of a 100 mL tall-form beaker fitted with a rubber bung

through which the electrochemical leads entered. An acetonitrile

solution of either the ligand or the ligand/co-ligand (1,10-

phenanthroline·monohydrate, 2,2Ј-bipyridine or 1,1-diphenylphos-

phanylmethane) mixture containing tetraethylammonium perchlo-

rate (ca. 10 mg) (Caution: perchlorate compounds are potentially ex-

plosive and should be handled in small quantities and with great care)

as a current carrier was electrolysed by using a platinum wire as

the cathode and a copper plate suspended from another platinum

wire as the sacrificial anode. Direct current was supplied by a pur-

pose-built d.c. power supply. Applied voltages of 5–15 V allowed

sufficient current flow for smooth dissolution of the metal. In all

cases, hydrogen was evolved at the cathode. The cell can be summa-

rized as Pt^(–)/CH₃CN + LH₂+ LЈ/M⁽⁺⁾, with H₂L representing the

Schiff-base ligand, LЈ is the additional ligand and M is either Co,

Ni, Cu, Zn or Cd. After electrolysis, the resulting solutions were

filtered to remove any particles of metal and then left to concen-

trate. This procedure yielded crystalline products. The solids were

washed with acetonitrile and diethyl ether and dried at room tem-

perature.

[NiL(bipy)]: Electrolysis of a solution of the ligand (0.146 g,

0.28 mmol) and 2,2Ј-bipyridine (0.043 g, 0.28 mmol) in acetonitrile

(50 cm³) at 8 V and 10 mA for 1.50 h dissolved 17 mg of nickel, E_f

= 0.52 molF^–1. IR (KBr): ν = 2916 (w), 1601 (s), 1562 (vw), 1552

˜

(vw), 1494 (s), 1473 (s), 1294 (m), 1269 (m), 1250 (vs), 1135 (vs),

962 (m), 846 (w), 812 (m), 760 (m), 743 (vw), 734 (w), 659 (m), 579

(m), 557 (s) cm^–1. MS (FAB): m/z = 732 [NiL(bipy)]⁺, 576 [NiL]⁺,

421 [NiL – Ts]⁺, 266 [NiL – 2Ts]⁺. C₃₇H₃₁N₅NiO₄S₂(732.51):

calcd. C 60.67, H 4.27, N 9.56, S 8.75; found C 60.33, H 4.19, N

9.49, S 9.07.

[NiL(phen)]: In a similar experiment to those described above, the

ligand (0.109 g, 0.21 mmol) and 1,10-phenanthroline (0.041 g,

0.20 mmol) in acetonitrile (50 cm³) was electrolysed at 10 V and

10 mA for 1.15 h and 12.8 mg of nickel metal was dissolved from

the anode, E = 0.51 molF^–1. IR (KBr): ν = 2922 (w), 1589 (s),

˜

f

1552 (w), 1518 (m), 1476 (m), 1427 (m), 1299 (m), 1252 (vs), 1178

(m), 1162 (m), 1134 (vs), 1051 (m), 964 (m), 846 (m), 752 (w), 727

(m), 658 (m), 557 (s) cm^–1. MS (FAB): m/z (%) = 756 (23)

[NiL(phen)]⁺, 600 [NiL(phen) – Ts]⁺, 576 [NiL]⁺, 421 [NiL – Ts]⁺,

265 [NiL – 2Ts]⁺. C₃₉H₃₁N₅NiO₄S₂(756.54): calcd. C 61.92, H

4.13, N 9.26, S 8.48; found C 62.09, H 4.65, N 8.64, S 7.85.

[CoL]: Electrochemical oxidation of a cobalt anode in a solution

of the ligand H₂L (0.199 g, 0.38 mmol) in acetonitrile (50 cm³) at

14.9 V and 10 mA for 2 h caused 22.4 mg of cobalt to be dissolved,

E = 0.51 molF^–1. IR (KBr): ν = 2922 (w), 1612 (s), 1597 (s), 1553

˜

f

(m), 1477 (s), 1443 (w), 1398 (w), 1384 (w), 1298 (s), 1259 (vs),

1232 (w), 1232 (w), 1133 (vs), 1087 (s), 1018 (w), 962 (s), 895 (m),

844 (m), 812 (m), 754 (m), 743 (m), 708 (m), 665 (s), 561 (s) cm^–1.

MS (FAB): m/z (%) = 1153 (11) [CoL]₂⁺, 576.1 (41) [CoL]⁺, 422

[CoL – Ts]⁺, 267 (26) [CoL – 2Ts]⁺. C₂₇H₂₃CoN₃O₄S₂(576.55):

calcd. C 56.25, N 7.29, H 4.02, S 11.12; found C 55.90, N 6.73, H

4.25, S 11.03.

[NiL(dppm)]: Electrochemical oxidation of a nickel anode in a solu-

tion of the ligand (0.132 g, 0.25 mmol) and dppm (0.099 g,

0.25 mmol) in acetonitrile (50 cm³) at 14 V and 10 mA for 1.4 h

caused 15 mg of nickel to be dissolved, E_f= 0.49 molF^–1. The re-

sulting solution was slowly evaporated at room temperature to give

red-brown crystals of [NiL(dppm)] suitable for X-ray studies. IR

[CoL(bipy)]: Electrolysis of a solution of the ligand (0.147 g,

0.28 mmol) and 2,2Ј-bipyridine (0.044 g, 0.28 mmol) in acetonitrile

(50 cm³) at 10 V and 10 mA for 1.5 h dissolved 16.0 mg of cobalt

(KBr): ν = 2920 (w), 1599 (m), 1546 (w), 1470 (vs), 1435 (s), 1389

˜

(m), 1307 (m), 1270 (m), 1246 (m), 1141 (vs), 1125 (s), 1086 (m),

1070 (m), 1030 (m), 962 (m), 833 (m), 810 (m), 785 (m), 745 (m),

699 (m), 560 (s) cm^–1. MS (FAB): m/z = 960 [NiLdppm]⁺, 575

[NiL]⁺, 421 [NiL – Ts]⁺. C₅₂H₄₅N₃NiO₄P₂S₂(960.72): calcd. C

from the anode, E = 0.48 molF^–1. IR (KBr): ν = 2933 (w), 1598

˜

f

(s), 1554 (w), 1475 (s), 1439 (m), 1384 (w), 1297 (m), 1259 (vs),

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2283

J. A. García-Vázquez et al.

FULL PAPER

65.01, N 4.37, H 4.72, S 6.45; found C 64.92, N 4.59, H 4.66, S

6.56.

1294 (m), 1254 (vs), 1133 (s), 1087 (m), 963 (m), 894 (m), 850 (m),

810 (m), 757 (m), 725 (m), 663 (s), 551 (vs) cm^–1. ¹H NMR

(CDCl₃): δ = 9.33 (d, ³J(1H–1H) = 3.1 Hz, 2 H, H^2,9), 8.70 (s, 1

H, CH=N), 8.38 (d, ³J(1H–1H) = 7.9 Hz, 2 H, H^5,6), 8.11 (d,

³J(1H–1H) = 7.9 Hz, 2 H, H^3,8), 7.95–6.78 (m, 28 H), 2.29 (s, 3 H,

[CuL]: A similar experiment to those described above (10 V, 5 mA,

1.25 h) with H₂L (0.125 g, 0.24 mmol) in acetonitrile (50 cm³) led

to the dissolution of 15 mg of metal, E_f= 1.01 molF^–1. From the

mother liquor, brown crystals of [CuL] suitable for X-ray studies

CH₃), 2.22 (s, 3 H, CH₃) ppm. MS (FAB): m/z = 763 [ZnL(phen)]

+

,

608 [ZnL(phen) – –

Ts]⁺, 582 [ZnL]⁺, 427 [ZnL Ts]⁺.

were obtained. IR (KBr): ν = 1600 (m), 1548 (m), 1474 (s), 1391

˜

C₃₉H₃₁N₅O₄S₂Zn (763.21): calcd. C 61.38, N 9.18, H 4.09, S 8.39;

found C 61.17, N 9.30, H 4.06, S 8.16.

(w), 1322 (m), 1300 (m), 1280 (s), 1245 (m), 1150 (vs), 1116 (m),

1087 (vs), 1051 (m), 959 (m), 852 (m), 758 (m), 665 (s), 564 (vs),

549 (m) cm^–1. MS (FAB): m/z = 581 [CuL]⁺, 426 [CuL – Tos]⁺.

C₂₇H₂₃CuN₃O₄S₂(581.16): calcd. C 55.80, N 7.30, H 4.31, S 10.70;

found C 55.61, N 7.23, H 3.99, S 11.03.

[CdL]: Electrolysis of a solution of the ligand (0.157 g, 0.30 mmol)

in acetonitrile (50 cm³) at 8 V and 10 mA for 1.6 h dissolved 33 mg

of cadmium from the anode, E = 0.49 molF^–1. IR (KBr): ν = 2926

˜

f

(w), 1613 (s), 1596 (m), 1555 (m), 1480 (s), 1444 (m), 1303 (s), 1251

(s), 1170 (w), 1133 (s), 1119 (vs), 1080 (vs), 983 (s), 892 (m), 842

(w), 804 (m), 757 (m), 705 (m), 663 (m), 556 (s) cm^–1. MS (FAB):

m/z = 631 [CdL]⁺. C₂₇H₂₃CdN₃O₄S₂(630.02): calcd. C 51.47, H

3.68, N 6.67, S 10.18; found C 50.98, H 3.61, N 6.64, S 9.99.

[CuL(bipy)]: A similar experiment to those described above (10 V,

10 mA, 1 h) with H₂L (0.194 g, 0.37 mmol) and 2,2Ј-bipyridine

(0.058 g, 0.37 mmol) in acetonitrile (50 cm³) led to the dissolution

of 23 mg of metal, E_f= 0.97 molF^–1. The resulting solution was

slowly evaporated at room temperature to give brown crystals suit-

[CdL(bipy)]: Electrolysis of a solution of the ligand (0.154 g,

0.30 mmol) and 2,2Ј-bipyridine (0.050 g, 0.32 mmol) in acetonitrile

(50 cm³) at 8 V and 10 mA for 1.5 h dissolved 31 mg of cadmium

able for X-ray studies. IR (KBr): ν = 2922 (w), 1605 (s), 1595 (s),

˜

1474 (vs), 1441 (w), 1297 (s), 1275 (vs), 1240 (m), 1142 (vs), 1068

(s), 956 (s), 894 (m), 847 (m), 810 (m), 768 (m), 760 (m), 734 (w),

680 (m), 561 (s), 549 (s) cm^–1. MS (FAB): m/z = 737 [CuL(bipy)]⁺,

581 [CuL]⁺, 425 [CuL – Tos]⁺. C₃₇H₃₁CuN₅O₄S₂(737.35): calcd. C

60.27, N 9.50, H 4.24, S 8.70; found C 59.98, N 9.61, H 4.30, S

8.50.

from the anode, E = 0.49 molF^–1. IR (KBr): ν = 2923 (w), 1615

˜

f

(m), 1594 (s), 1475 (s), 1438 (s), 1385 (m), 1296 (m), 1282 (m), 1253

(vs), 1136 (vs), 1086 (s), 1018 (m), 975 (s), 888 (m), 842 (m), 829

(m), 811 (m), 760 (s), 735 (w), 663 (s), 547 (s) cm^–1. ¹H NMR

(CDCl₃): δ = 8.79 (m, 2 H, H^6,6Ј), 8.62 (s, 1 H, CH=N), 8.04 (m,

2 H, H^3,3), 7.87–6.79 (m, 1 H, aromatics), 2.29 (s, 3 H, CH₃), 2.28

(s, 3 H, CH₃) ppm. MS (FAB): m/z = 786 [CdL(bipy)]⁺, 632

[CdL]⁺, 477 [CdL – Ts]⁺. C₃₇H₃₁CdN₅O₄S₂(786.20): calcd. C

56.52, H 3.97, N 8.91, S 8.16; found C 56.89, H 3.73, N 8.23, S

8.12.

[CuL(phen)]: A similar experiment to those described above (12 V,

5 mA, 1.20 h) with H₂L (0.130 g, 0.25 mmol) and 1,10-phenan-

throline (0.049 g, 0.25 mmol) in acetonitrile (50 cm³) led to the dis-

solution of 15 mg of metal, E = 1.05 molF^–1. IR (KBr): ν = 2924

˜

f

(w), 1593 (m), 1548 (w), 1514 (m), 1474 (m), 1426 (m), 1295 (s),

1273 (s), 1239 (m), 1139 (vs), 1086 (s), 956 (s), 849 (m), 727 (m),

707 (m), 664 (s), 573 (m), 552 (m) cm^–1. MS (FAB): m/z = 761

[CuL(phen)]⁺, 581 [CuL]⁺, 425 [CuL – Tos]⁺. C₃₉H₃₁CuN₅O₄S₂

(761.37): calcd. C 61.52, N 9.20, H 4.10, S 8.42; found C 60.95, N

9.43, H 4.15, S 8.32.

[CdL(phen)]: A solution of the ligand (0.156 g, 0.30 mmol) and

1,10-phenanthroline (0.061 g, 0.31 mmol) in acetonitrile (50 cm³)

was electrolysed at 8 V and 10 mA for 1.5 h and 33 mg of cadmium

metal was dissolved from the anode, E_f= 0.52 molF^–1. IR (KBr):

ν = 2926 (w), 1617 (m), 1594 (m), 1517 (w), 1475 (s), 1427 (s), 1297

˜

[ZnL]: A similar experiment to those described above (15 V, 10 mA,

2 h) with H₂L (0.196 g, 0.38 mmol) in acetonitrile (50 cm³) led to

the dissolution of 25.4 mg of metal, E_f= 0.52 molF^–1. IR (KBr):

(m), 1255 (s), 1153 (m), 1135 (vs), 1087 (s), 974 (m), 854 (m), 727

1

3

(m), 651 (m), 550 (s) cm^–1. H NMR (CDCl₃): δ = 9.14 (d, J(1H–

1H) = 4.4 Hz, 2 H, H^2,9), 8.70 (s, 1 H, CH=N), 8.30 (d, ³J(1H–1H)

= 7.9 Hz, 2 H, H^3,8), 7.97–6.80 (m, 28 H), 2.29 (s, 3 H, CH₃),

2.28 (s, 3 H, CH₃) ppm. MS (FAB): m/z = 811 [CdL(phen)]⁺, 656

[CdL(phen) – Ts]⁺. C₃₉H₃₁CdN₅O₄S₂(810.23): calcd. C 57.81, H

3.86, N 8.64, S 7.91; found C 57.72, H 3.98, N 8.04, S 7.76.

ν = 2931 (w), 1612 (s), 1596 (s), 1553 (m), 1475 (vs), 1394 (m), 1298

˜

(vs), 1275 (vs), 1257 (vs), 1142 (vs), 1089 (s), 968 (s), 847 (m), 834

(m), 812 (m), 709 (m), 663 (s), 563 (s), 551 (s) cm^–1. ¹H NMR

(CDCl₃): δ = 8.76 (s, 1 H, CH=N), 7.98–6.82 (m, 28 H, aromatic),

2.30 (s, 3 H, CH₃), 2.16 (s, 3 H, CH₃) ppm. MS (FAB): m/z = 581

[ZnL]⁺, 427 [ZnL – Ts]⁺. C₂₇H₂₃N₅O₄S₂Zn (611.01): calcd. C 55.63,

N 7.21, H 3.98, S 11.00; found C 55.43, N 7.17, H 3.90, S 11.23.

X-ray Crystallographic Studies: Intensity data sets for compounds

1, 2, 3 and 6 were collected by using a MACH3 Enraf–Nonius

diffractometer (Cu-K_αradiation; λ = 1.54184 Å) equipped with a

graphite monochromator. The ω and φ scan techniques were em-

ployed to measure the intensities of these crystals. Intensity data

for compounds 4, 5 and 7 were collected by using a Smart CCD-

1000 Bruker diffractometer (Mo-K_αradiation, λ = 0.71073 Å)

equipped with a graphite monochromator. The ω scan technique

was employed in these cases. All crystals were studied at 293 K.

Decomposition of the crystals was not detected during data collec-

tion. The intensities of all the data sets were corrected for Lo-

rentzian and polarization effects. Absorption effects in compounds

1, 2, 3 and 6 were corrected by using semi-empirical ψ scans; the

absorption effects in compounds 4, 5 and 7 were corrected by using

the SADABS program.^[73]The crystal structures of all the com-

pounds were solved by direct methods. Crystallographic programs

[ZnL(bipy)]: A similar experiment to those described above (15 V,

10 mA, 1.5 h) with H₂L (0.149 g, 0.29 mmol) and 2,2Ј-bipyridine

(0.045 g, 0.29 mmol) in acetonitrile (50 cm³) led to the dissolution

of 19 mg of metal, E = 0.52 molF^–1. IR (KBr): ν = 2931 (w), 1614

˜

f

(m), 1597 (w), 1475 (m), 1440 (m), 1299 (m), 1274 (m), 1261 (m),

1248 (m), 1143 (vs), 1121 (s), 1108 (m), 1089 (s), 965 (m), 858 (m),

845 (m), 765 (m), 750 (w), 734 (w), 663 (m), 549 (s) cm^–1. ¹H NMR

(CDCl₃): δ = 8.98 (m, 2 H, H^6,6Ј), 8.53 (s, 1 H, CH=N), 8.11 (m,

2 H, H^3,3Ј), 7.92–6.77 (m, 28 H), 2.30 (s, 3 H, CH₃), 2.20 (s, 3 H,

CH₃) ppm. MS (FAB): m/z = 738 [ZnL(bipy)]⁺, 582 [ZnL]⁺, 427

[ZnL – Ts]⁺. C₃₇H₃₁N₅O₄S₂Zn (739.18): calcd. C 60.12, N 9.47, H

4.23, S 8.67; found C 60.17, N 9.52, H 4.19, S 8.66.

[ZnL(phen)]: A similar experiment to those described above (15 V,

10 mA, 1.7 h) with H₂L (0.163 g, 0.31 mmol) and 1,10-phenan- in the SHELX97 collection were used for structure solution and

throline (0.062 g, 0.31 mmol) in acetonitrile (50 cm³) led to the dis-

refinement.^[74]Scattering factors were those provided with the

SHELX programme system. Missing atoms were located in the dif-

ference Fourier map and included in subsequent refinement cycles.

solution of 21 mg of metal, E = 0.51 molF^–1. IR (KBr): ν = 2931

˜

f

(w), 1614 (s), 1555 (w), 1517 (m), 1476 (s), 1425 (m), 1385 (m),

2284

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Eur. J. Inorg. Chem. 2011, 2273–2287

Homoleptic and Heteroleptic Co, Ni, Cu, Zn and Cd Compounds

The structures were refined by full-matrix least-squares refinement

on F². Hydrogen atoms were placed geometrically and refined by

using a riding model with U_isoconstrained at 1.2 (for non-methyl

groups) and at 1.5 (for methyl groups) times U_eqof the carrier C

atom. For all structures non-hydrogen atoms were anisotropically

refined and in the last cycles of refinement a weighting scheme was

used, with weights calculated using the formula w = 1/[σ²(F_o²) +

2

(aP)²+ bP], in which P = (F_o+ 2F_c)/3.

Table 6. Summary of the crystallographic data and refinement for compounds.

H₂L

[NiL]

[CuL]

[NiL(dppm)]

Empirical formula

Formula mass

Crystal size [mm]

Temperature [K]

Wavelength

Crystal system

Space group

Unit cell dimensions

a [Å]

b [Å]

c [Å]

α [°]

β [°]

C₂₇H₂₅N₃O₄S₂

519.62

0.40ϫ0.24ϫ0.16

293(2)

1.54184

orthorhombic

Pca2₁

C₂₇H₂₃N₃O₄S₂Ni

576.31

0.24ϫ0.16ϫ0.12

293(2)

C₂₇H₂₃N₃O₄S₂Cu

581.14

0.48ϫ0.48ϫ0.12

293(2)

C₅₂H₄₅N₃O₄S₂P₂Ni

960.68

0.30ϫ0.27ϫ0.07

293(2)

1.54184

0.71073

triclinic

¯

P1

20.3993(6)

7.1230(4)

17.5386(7)

90.00

2548.43(19)

4

2.216

8.535(2)

8.5316(10)

11.0240(3)

13.7471(13)

95.373(4)

100.113(11)

98.568(4)

1249.09(19)

2

9.046(2)

10.9738(19)

13.735(4)

94.36(3)

99.532(17)

98.80(3)

1247.0(6)

2

3.028

10.438(3)

25.400(6)

82.552(4)

82.566(4)

87.945(4)

2357.7(10)

2

γ [°]

Volume [Å³]

Z

μ [mm^–1]

3.136

0.617

F(000)

Reflections collected

Independent reflections

1088

2632

2631

596

5209

4989

598

5213

4993

1000

26039

7836

[R(int) = 0.1842]

2631/1/326

1.041

R₁= 0.0396

wR₂= 0.0931

R₁= 0.0803

wR₂= 0.1088

0.198 and –0.253

[R(int) = 0.0769]

4989/0/334

0.990

R₁= 0.0615

wR₂= 0.1530

R₁= 0.1497

wR₂= 0.1926

0.702 and –0.871

[R(int) = 0.2260]

3939/6/223

1.060

R₁= 0.0902

wR₂= 0.2251

R₁= 0.1036

wR₂= 0.2405

2.387 and –1.865

[R(int) = 0.0888]

7836/336/689

1.001

R₁= 0.0536

wR₂= 0.1148

R₁= 0.1076

wR₂= 0.1366

0.461 and –0.614

Data/restraints/parameters

Goodness-of-fit

Final R indices

[IϾ2σ(I)]

R indices (all data)

Largest diff. peak and hole

[eÅ^–3]

[CoL(phen)]

[ZnL(phen)]

[CuL(bipy)]

Empirical formula

Formula mass

Crystal size [mm]

Temperature [K]

Wavelength

Crystal system

Space group

Unit cell dimens.

a [Å]

C₃₉H₃₁N₅O₄S₂Co

756.74

0.57ϫ0.23ϫ0.07

293(2)

0.71073

monoclinic

P2₁/c

C₃₉H₃₁N₅O₄S₂Zn

763.18

0.20ϫ0.10ϫ0.03

293(2)

0.71073

monoclinic

P2₁/c

C₃₇H₃₁N₅O₄S₂Cu

737.33

0.20ϫ0.20ϫ0.12

293(2)

1.54184

monoclinic

C2/c

18.030(4)

12.778(3)

16.791(3)

90.000

18.171(8)

12.764(5)

16.927(7)

90.000

37.287(6)

12.359(3)

17.05(3)

b [Å]

c [Å]

α [°]

90.000

β [°]

γ [°]

116.245(4)

90.000

1141.6(4)

4

116.855(7)

90.000

3502(2)

107.093(14)

90.000

7509(13)

8

Volume [Å³]

Z

4

μ [mm^–1]

0.665

0.870

2.220

F(000)

1564

21180

7077

1576

19890

4268

3048

6331

6227

Reflections collected

Independent

reflections

Data/restraints/parameters

Goodness-of-fit

Final R indices

[IϾ2σ(I)]

[R(int) = 0.0856]

7077/0/460

1.085

R₁= 0.0774

wR₂= 0.1860

R₁= 0.1954

wR₂= 0.2656

1.041 and –0.684

[R(int) = 0.1981]

4268/0/461

1.001

R₁= 0.0772

wR₂= 0.1600

R₁= 0.2172

wR₂= 0.2168

0.514 and –0.505

[R(int) = 0.0532]

6227/0/442

1.001

R₁= 0.0611

wR₂= 0.1149

R₁= 0.2040

wR₂= 0.1294

0.358 and –0.632

R indices (all data)

Largest diff. peak and hole

[e·Å^–3]

Eur. J. Inorg. Chem. 2011, 2273–2287

www.eurjic.org

2285

J. A. García-Vázquez et al.

FULL PAPER

[11]

[12]

J. Sánchez-Piso, J. A. García-Vázquez, J. Romero, M. L.

Durán, A. Sousa-Pedrares, E. Labisbal, O. R. Nascimento, In-

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Compound 7 is a very weak diffractor and did not give detectable

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[15]

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Pertinent details of the data collections and structure refinements

are summarized in Table 6. Further details regarding the data col-

lections, structure solutions and refinements are included in the

Supporting Information. ORTEP3 drawings^[77]with the numbering

schemes used are shown in Figures 1–6.

CCDC-805162 (for 1), -805163 (for 5), -805164 (for 3), -805165 (for

6), -805166 (for 2), -805167 (for 4), -805168 (for 7) contain the

supplementary crystallographic data for this paper. These data can

be obtained free of charge from The Cambridge Crystallographic

Data Centre via www.ccdc.cam.ac.uk/data_request/cif.

Supporting Information (see the footnote on the first page of this

article): The crystal packing of the ligand and FAB mass spectra

of the metal complexes are described, hydrogen-bonding param-

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compounds 2, 3, 5–7 (Table S2), crystal structure of [NiL] showing

C–H···O interactions (Figure S1), ORTEP diagrams of the molecu-

lar structures of [CoL(phen)] and [ZnL(phen)] (Figures S2 and S3).

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Acknowledgments

This work was supported by the Spanish Xunta de Galicia (grant

number PGIDIT07PXIB203038PR) and by the Ministerio de Cien-

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Received: December 27, 2010

Published Online: April 1, 2011

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2287

Article Doi

Synthesis and characterization of homoleptic and heteroleptic cobalt, nickel, copper, zinc and cadmium compounds with the 2-(tosylamino)-N-[2- (tosylamino)benzylidene]aniline ligand

DOI: 10.1002/ejic.201001356

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