Journal of Molecular Structure 930 (2009) 88–94

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Journal of Molecular Structure

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Cationic cobaltammines as anion receptors: Synthesis, spectroscopic and X-raystructural study of biologically important saccharinate salt,[cis-Co(en)2(N3)2](C7H4NSO3)

Rajni Sharma a, Raj Pal Sharma a,*, Konstantin Karaghiosoff b, Thomas M. Klapoetke b,Miguel Quiros c, Juan M. Salas c,*

a Department of Chemistry & Center of Advanced Studies, Panjab University, Chandigarh, U.T. 160014, Indiab Department of Chemistry, Ludwig-Maximilians University of Munich, Butenandtstrasse, Germanyc Departamento de Quimica Inorganica, Facultad de Ciencias, Universidad de Granada, 18071 Granada, Spain

a r t i c l e i n f o

Article history:Received 11 March 2009Received in revised form 22 April 2009Accepted 24 April 2009Available online 5 May 2009

Keywords:Cobalt (III)Coordination chemistryX-ray crystallographySpectroscopySaccharinateAnion receptor

0022-2860/$ - see front matter � 2009 Elsevier B.V. Adoi:10.1016/j.molstruc.2009.04.043

* Corresponding authors. Tel.: +91 0172 2544433;Sharma), tel.: +34 958248525; fax: +34 958248526 (J

E-mail addresses: rpsharma@yahoo.co.in (R.P. SSalas).

a b s t r a c t

To explore the potential of cationic cobaltammine as anion receptor, single crystals of cis-diazidobis(eth-ylenediamine)cobalt(III) saccharinate have been obtained by slowly mixing separately dissolved solu-tions of [cis-Co(en)2(N3)2]NO3 and NaC7H4SO3N in aqueous medium in nearly 1:1 molar ratio.Elemental analyses, solubility product measurement, molar conductance studies and spectroscopic tech-niques (IR, UV/Visible, 1H and 13C NMR) were employed for characterizing the complex salt. The complexsalt crystallized in the triclinic space group P1 with cell dimensions a = 7.2638 (15) Å, b = 11.424 (2) Å,c = 11.953 (2) Å, Z = 2, V = 894.8 (3) Å3, R1 = 0.0401 and wR2 = 0.0910. Single crystal X-ray structure deter-mination revealed supramolecular assemblies via hydrogen bonding network between ionic groups andNAH groups of coordinated ethylenediamine molecules i.e., second-sphere coordination.

� 2009 Elsevier B.V. All rights reserved.

1. Introduction

Anions play important roles in both chemical and biochemicalprocesses. Anion coordination chemistry, the binding of anionsby receptor molecules has recently been recognized and developedas a new area of coordination chemistry [1,2]. This is because oftheir varied shape, size [3], charge, high energy of solvation andlower lewis basicities [4]. Recovery and recycling of such anionsis necessary as some of these show harmful effects while othersshow useful applications. Molecular recognition of the anionic sub-strate results from the readout of specific information concerningthe anion to be bound. This information must be stored at themolecular level within the structure of the receptor molecule. Toachieve the desired sensitivity and selectivity, the combination ofelectrostatic interaction, hydrogen bonding and stacking effectsall need to be taken into consideration when designing an artificialanionic host or sensor. Therefore, search for new anion receptors,which may find potential applications [5] in the area of analyticalchemistry, biology, catalysis, etc. is important.

ll rights reserved.

fax: +91 0172 2545074 (R.P..M. Salas).harma), jsalas@ugr.es (J.M.

Anionic benzosulfimide entities are of ubiquitous importance inbiology. Saccharin (C7H5SO3N), also called o-benzosulfimide in theform of its water soluble salts is widely used as non-calorific arti-ficial sweetener for diabetics. Saccharin, its derivatives and somemetal saccharinates are found to be enzymatic inhibitors [6] andelectroplating brighteners. The saccharine complexes also havebeen found to have potential use as an antidote for metal poisoning[7]. As a result of the recent finding about the potential carcino-genic [8] nature of saccharin, the salts and complexes of this com-pound have been a subject of rather extensive studies. Metalcomplexes of saccharin may also have relevance for an under-standing of its effect on human metabolism [9,10]. Apart from itsbiological relevance, the proximity of three different functionalgroups, the good crystalline habits of its metal salts/complexesand the exceptional versatility of structural patterns exhibited inthe solid state, saccharinate ion has proved to be outstanding sys-tem for research.

Cobalt(III) complexes continue to receive attention [11] due tothe important role it plays in the development of inorganic chem-istry: (i) as catalyst in the synthesis and hydrolysis of peptides[12a] (ii) as central metal atom [12b] in vitamin B12 (iii) for its po-tent influence on human pathophysiological conditions resultingeither from its absence in the body leading to anemic symptoms[13] or its excessive presence leading to toxic effects resulting in

Table 1Crystal data and structure refinement parameters for [cis-Co(en)2(N3)2]C7H4SO3N.

Empirical formula C11H20CoN11O3SFormula weight 445.37Wavelength 0.71073 ÅCrystal system TriclinicSpace group P 1Unit cell dimensions a = 7.2638(15) Å

b = 11.424(2) Åc = 11.953(2) Åa = 110.29(3)�b = 100.50(3)�c = 97.38(3)�

Volume 894.8(3) Å3

Z 2Calculated density 1.633 Mg/m3

Absorption coefficient 1.103 mm�1

F(0 0 0) 460

R. Sharma et al. / Journal of Molecular Structure 930 (2009) 88–94 89

heart disease [14] (iv) in chirality transfer [15]. While a large numberof azido divalent metal complexes have been reported, their corre-sponding cobalt(III) complexes are very limited [16–18]. Moreoverthere are only few reports of X-ray diffraction studies of the azido co-balt(III) salts in literature [19–22]. Two isomers cis and trans of thestarting material are reported [23]. Therefore, in view of excitingchemistry of cationic cis-diazidocobaltammine and biologicallyimportant saccharinate anion, it was thought of interest to synthe-size the title complex salt, in continuation [24] of our interest in co-balt(III) salts. We have undertaken an extensive research program toexploit [cis-Co(en)2(N3)2]+ cation as anion receptor [25]. In this paperwe report the synthesis, characterization and single crystal X-raystructure determination of cis-diazidobis(ethylenediamine)cobalt(III) saccharinate. This is the first structural report of a saccharinatesalt containing [cis-Co(en)2(N3)2]+ ion.

Crystal size 0.10 � 0.07 � 0.03 mmTheta range for data collection 1.87–28.02�Limiting indices 9 h 6 9, �15 6 k 6 14, �15 6 l 6 15Reflections collected/unique 10337/4055 [R(int) = 0.0214]Completeness to theta = 28.02 92.5%Absorption correction Semi-empirical from equivalentsMax. and min. transmission 0.9073 and 0.7217Refinement method Full-matrix least-squares on F2

Weighting scheme w = 1/[r2(Fo2) + (0.05P)2 + 0.3P]where P = (Fo2 + 2Fc2)/3

Data/restraints/parameters 4055/0/244Goodness-of-fit on F2 1.077Final R indices [I > 2sigma(I)] R1 = 0.0356, wR2 = 0.0910R indices (all data) R1 = 0.0401, wR2 = 0.0932Largest diff. peak and hole 0.522 and �0.284 e �3

Table 2Selected bond lengths [Å] and bond angles [�] for [cis-Co(en)2(N3)2]C7H4SO3N.

[cis-Co(en)2(N3)2]+

Co1–N1 1.961(3) C2–N2 1.481(5)Co1–N2 1.949(3) N3–C3 1.481(5)Co1–N3 1.959(3) C3–C4 1.502(5)Co1–N4 1.933(3) C4–N4 1.482(5)Co1–N5 1.934(3) N5–N6 1.213(4)Co1–N8 1.939(3) N6–N7 1.149(4)N1–C1 1.483(5) N8–N9 1.215(4)C1–C2 1.507(5) N9–N10 1.153(4)

N1–Co1–N3 92.9(1) Co1–N5–N6 123.2(2)N1–Co1–N8 87.5(1) N5–N6–N7 175.0(4)N3–Co1–N5 84.9(1) Co1–N8–N9 120.5(3)N5–Co1–N8 94.7(1) N8–N9–N10 175.4(4)N1–Co1–N2 85.3(1) Co1–N1–C1 109.3(2)N1–Co1–N4 91.1(1) N1–C1–C2 107.5(3)N3–Co1–N2 92.2(1) C1–C2–N2 105.2(3)N3–Co1–N4 85.7(1) Co1–N2–C2 109.6(2)N2–Co1–N5 91.8(1) Co1–N3–C3 108.8(2)N4–Co1–N5 91.7(1) N3–C3–C4 106.5(3)N2–Co1–N8 88.3(1) C3–C4–N4 107.5(3)N4–Co1–N8 93.9(1) Co1–N4–C4 110.5(2)

Saccharinate ionS1–O1 1.449(2) C6–C7 1.388(4)S1–O2 1.443(3) C7–C8 1.372(6)S1–N11 1.618(3) C8–C9 1.373(5)S1–C7 1.767(4) C9–C10 1.383(5)C5–N11 1.351(4) C10–C11 1.373(6)C5–O3 1.248(4) C6–C11 1.382(5)C5–C6 1.502(5)

C7–S1–O2 111.7(2) C6–C7–S1 106.4(3)N11–S1–O2 111.7(2) C6–C7–C8 123.1(3)O1–S1–O2 114.8(1) C7–C8–C9 116.6(3)C7–S1–N11 97.4(1) C8–C9–C10 121.7(4)S1–N11–C5 111.4(3) C9–C10–C11 121.0(4)N11–C5–C6 113.2(3) C10–C11–C6 118.6(4)C5–C6–C7 111.5(3)

2. Experimental

Analytical grade reagents were used without any further purifi-cation. [cis-Co(en)2(N3)2] NO3 has been prepared according to liter-ature method [23,26].

2.1. Instruments

Cobalt was determined by standard method [27] and C, H, Nwere estimated micro-analytically by automatic Perkin Elmer2400 CHN elemental analyzer. IR spectra were recorded as KBr pel-lets on Perkin Elmer Spectrum RXFT-IR system. 1H and 13C NMRspectra were recorded in DMSO-d6 using JEOL AL 300 MHz FTNMR spectrophotometer with TMS as internal reference. UV/Visible spectra were recorded in DMSO using Hitachi 330spectrometer.

2.2. Synthesis of cis-[Co(en)2(N3)2]C7H4SO3N

The title complex salt was prepared by adding a stirred aqueoussolution of sodium saccharinate to a filtered saturated solution of[cis-Co(en)2(N3)2]NO3 in stoichiometric amounts. One gram of [cis-Co(en)2(N3)2]NO3 was dissolved in 50 ml hot water and filtered.To this solution was added 0.7410 g of sodium saccharinate dis-solved in minimum amount of water. The reddish brown colouredprecipitates appeared almost immediately which were filtered,washed with water and air-dried. Single crystals suitable for X-raystructural studies were obtained by repeating the reaction on asmaller scale in a more dilute solution allowing the crystals to growover a longer time period. The yield of the novel complex salt ob-tained was 80%. The complex was freely soluble in water and DMSObut insoluble in ethanol. The melting point of the newly formedcomplex salt was above 200 oC. The elemental analyses were consis-tent with the composition of [cis-Co(en)2(N3)2]C7H4SO3N (Found:C,30.2; H,4.2; N,34.1; Co,12.9 for the complex salt, the calculatedvalues: C,29.6; H,4.5; N,34.5; Co,13.2%).

2.3. X-ray structure determination

Intensity data for a crystal (0.10 � 0.07 � 0.03 mm) were mea-sured at room temperature on a Bruker Smart Apex CCD diffrac-tometer fitted with graphite monochromatized MoKa,k = 0.71073 Å, such that hmax was 28.02. Of the total reflectionsmeasured, 4055 were unique. This structure was solved using theSHELX-97 program [28] and refined by a full-matrix least squaresprocedure based on F2. Crystallographic data is given in Table 1. Se-lected interatomic parameters are given in Table 2 and numberingscheme employed is shown in Fig. 1 which was drawn using theXtalGX [29].

Fig. 1. ORTEPIII view and atom numbering scheme for title compound.

Fig. 3. Overlapped infrared spectrum of [cis-Co(en)2(N3)2]C7H4SO3N with sodiumsaccharinate. IR spectrum of [cis-Co(en)2(N3)2]C7H4SO3N (solid line). IR spectrum ofsodium saccharinate (broken line).

90 R. Sharma et al. / Journal of Molecular Structure 930 (2009) 88–94

3. Results and discussion

In the present work, [cis-Co(en)2(N3)2]NO3 was reacted with so-dium salt of saccharinate and a novel complex salt cis-diazid-obis(ethylenediamine)cobalt(III) saccharinate was obtained inalmost quantitative yield as air-stable reddish brown crystals.The newly synthesized complex was soluble in water and DMSO.The composition of the complex salt has been confirmed by ele-mental analyses and spectroscopic techniques (UV/Visible, IR andNMR). The crystal structure of the title complex has been estab-lished by single crystal X-ray crystallography.

3.1. Measurement of solubility product

Solubility of ionic salts in water differs to a great extent and onthe basis of solubility criterion, the salts are classified into threecategories (a) solubility > 0.1 M (soluble), (b) solubility between0.01 and 0.1 M (slightly soluble) and (c) solubility < 0.01 M are(sparingly soluble). The solubility measurements at room temper-ature showed that [cis-Co(en)2(N3)2]NO3 and [cis-Co(en)2(N3)2]C7

H4SO3N are sparingly soluble in water but it was more true forthe former. The solubility product of [cis-Co(en)2(N3)2]C7H4SO3Nwas 1.8 � 10�4 as compared to 9.0 � 10�4 of [cis-Co(en)2(N3)2]NO3

which indicated that the affinity or binding of [cis-Co(en)2(N3)2]+

was slightly greater for the saccharinate ion as compared to the ni-

Fig. 2. Plot of square root of concentration versus molar conductance.

trate ion. This was further supported by the hydrogen bondinginteractions discussed in detail in Section 4 while discussing thecrystal structure.

3.2. Molar conductance measurement

The conductance measurement studies in aqueous medium at25 �C were made and the plot of molar conductance (K) versussquare root of concentration is presented in Fig. 2. When the con-centration was extrapolated to zero, it gave Ko = 55.7 for [cis-Co(en)2(N3)2]C7H4SO3N which is within the range reported for1:1 electrolyte. The corresponding value of Ko for [cis-Co(en)2(N3)2] NO3 was measured to be 139.6. It was obvious thatthe nitrate salt behaves as 1:1 electrolyte in aqueous mediumbut the title complex salt is much less ionized in the solution ascompared to the nitrate salt. This may be ascribed to ion pairformation.

3.3. Spectroscopic characterization

IR spectrum of the newly synthesized complex has been re-corded in the region 4000–400 cm�1 and tentative peak assign-ments have been made on the basis of earlier reports inliterature [30]. IR bands at 792 cm�1 was assigned to CH2 rockingregion and a band at 1573 cm�1 was assigned to NH2 asymmetricdeformation which indicates the cis geometry of the cationic com-plex [31]. The two strong absorption bands at 2026 and 2063 cm�1

for asymmetric stretching frequency of azide group confirmed thecis geometry. Some characteristics peaks for ionic saccharinate inthe IR spectrum of the novel complex were assigned by comparingit with related compounds [32]. Also the overlapped infrared spec-trum of the title complex with sodium saccharinate is shown inFig. 3 which is comparable. The peak at 2854 cm�1 was due tothe ring m(C–H) vibrations. The m(CO) peak appeared at1618 cm�1. The peak at 1334 cm�1 was assigned to m(CN) ringvibration. The mas(SO2) peak appeared as a strong peak at1263 cm�1 whilst the ms(SO2) bonds appeared as a strong peak at1141 cm�1. The band at 1287 cm�1 was assigned to ring m(CC).

The electronic spectrum of the complex salt has been recordedin DMSO. The UV/Visible absorption spectrum of the title complexsalt was identical with that of the complex cation [23]. The com-plex salt absorbed strongly at 523 and 310 nm corresponding tod–d transitions [33] typical for octahedral low spin cobalt(III).These transitions were from 1A1g ground state of Cobalt (III) to sin-glet state 1T1g (low energy) and from 1A1g ground state to 1T2g

(higher energy).NMR spectra of the newly synthesised complex salt were re-

corded in DMSO-d6. The chemical shift values were expressed as

Fig. 4. (a) 1H NMR spectrum of [cis-Co(en)2(N3)2]C7H4SO3N and (b) 13C NMR spectrum of [cis-Co(en)2(N3)2]C7H4SO3N.

R. Sharma et al. / Journal of Molecular Structure 930 (2009) 88–94 91

d value (ppm) downfield from tetramethylsilane as an internalstandard. In 1H NMR, the four signals at 5.1, 4.8, 4.1 and 3.8 ppmwere attributed to nitrogen protons [34] of ethylenediamine whilesignal due to CH2 protons of ethylenediamine group were observedat 2.5 ppm. The signal at 7.6 ppm was assigned to the protons ofaromatic region. Fig. 4(a) shows the 1H NMR spectrum of the titlecomplex salt.

The 13C NMR spectrum showed the characteristic signal at45 ppm for carbon atoms of ethylenediamine. The signals at 145,121.2, 123.1, 132.4, 134.4, 131.9 and 166.9 ppm were assigned toC-1, C-2, C-3, C-4, C-5, C-6 and C-7 of the saccharinate ion [35],respectively. 13C NMR spectrum of the title complex salt is shownin Fig. 4(b).

4. Crystal structure

4.1. Coordination geometry and bonding

From the structural point of view, featuring sulfocarboximidemoiety and thus three different functional groups (imino, sulfonyland carbonyl) connected to each other and also condensed to a

benzene ring, saccharin has attracted appreciable scientific atten-tion. The deprotonated forms of saccharin show an extraordinaryvariety in the type of bonding in metal salts and complexes: ionic[36,37], coordinated as monodentate ligated via the nitrogen [38]atom, the carbonyl oxygen atom [39] or the sulfonyl [40] oxygenatom, bidentate amidato like bridging [41] or several of thesemodes within the same structure. Some modes are shown belowin Fig. 5.

On the basis of elemental analysis and spectroscopic studies, itwas proposed that one of the following three ionic structures maybe true i.e. [cis-Co(en)2(N3)2][C7H4SO3N], [cis-Co(en)2(N3)(H2O)]N3

[C7H4SO3N], [cis-Co(en)2(H2O)(C7H4SO3N)](N3)2, corresponding toionic or coordinated saccharinate and/or azide.

It is worth mentioning here that the following reactions have al-ready been reported in literature [42] which involve replacementof azide group by sulphite or oxalato group when heated in aque-ous solution:

½cis-CoðenÞ2ðN3Þ2�NO3 þ Na2SO3 !H2O

Heat½CoðenÞ2ðN3ÞðSO3Þ1�5H2O

½cis-CoðenÞ2ðN3Þ2�NO3 þ Na2C2O4 !H2O

Heat½CoðenÞ2ðN3ÞðC2O4ÞH2O

Fig. 5. Ionic and coordinated modes of saccharinate.

Table 3A comparison of bond distances (Å) and bond angles (o) for the cation (Panel A) and anion (Panel B).

Formula of the compound Bond lengths Bite angles Reference

Co–N1 Co–N2 Co–N3 Co–N4 N–Co–N N–Co–N

Panel A[cis-Co(en)2(N3)2]2SiF6 1.952(2) 1.966(2) 1.971(2) 1.964(2) 85.78(7) 85.72(7) [25a][cis-Co(en)2(N3)2]2 BF4NO3 1.967(2) 1.965(3) 1.954(2) 1.968(2) 85.24(10) 85.23(11) [25a][cis-Co(en)2(N3)2]SCN 1.974(2) 1.977(2) 1.997(2) 1.922(2) 85.51(7) 87.51(7) [25b][cis-Co(en)2(N3)2] C6H3ClNO5S. H2O 1.969(2) 1.962(2) 1.960(2) 1.952(2) 86.03(9) 85.97(9) [25c][cis-Co(en)2(N3)2] C9H11SO3. 0.5H2O 1.955(2) 1.964(2) 1.970(2) 1.960(2) 85.83(9) 85.55(9) [25d][cis-Co(en)2(N3)2] C6H2N3O7 1.977(2) 1.956(2) 1.960(2) 1.959(2) 85.07(7) 85.68(9) [25e][cis-Co(en)2(N3)2] C7H4SO3N 1.961(3) 1.949(3) 1.959(3) 1.959(3) 85.30(1) 85.70(1) P.W.

Mode of bonding Formula of the compound Bond distances Bond angles Reference

C–S S–O S–N C–N C–O \CSO \CSN \OSN \OSO

Panel BNeutral C7H5NSO3 – 1.42 1.66 1.37 1.21 – 92.4 – 117.5 [6]Ionic NaC7H4NSO3 – 1.44 (2) – – 1.23 (3) – – – 112.9 (1) [43]Ionic KC7H4NSO3 – 1.44 (3) – – 1.22 (5) – – – 112.4 (2) [43]Ionic NH4C7H4NSO3 – 1.45 (1) – – 1.24 (2) – – – 113.4 (1) [43]Coordinated SO3C7H4NSn (C6H5)3C2H5OH 1.77 (8) 1.42 (9) 1.63 (8) 1.37 (9) 1.25 (1) 113.0 (5) 94.8 (4) 110.9 (4) 116.1 (4) [44]Coordinated C10N4COPb (C7H4NSO3)2H2O 1.75 (16) 1.48 (12) 1.61 (13) 1.30 (19) 1.23 (20) 112.1 (8) 96.8 (7) 112.1 (7) 116.1 (7) [45]Ionic [Co(en)2(N3)2] C7H4SO3N 1.72 (2) 1.44 (17) 1.62 (18) 1.37 (3) 1.21 (3) 111.3(10) 97.3 (10) 110.3 (10) 114.7 (10) P.W.

P.W., Present work.

92 R. Sharma et al. / Journal of Molecular Structure 930 (2009) 88–94

X-ray structure determination [21] confirmed the structuralformulae of these complexes as given above.

To determine the structure unambiguously, the single crystal X-ray structure determination was carried out which revealed thatthe title complex salt consisted of [Co(en)2(N3)2]+ cation and sac-charinate anion. In the complex cation [cis-Co(en)2(N3)2]+, the cen-tral metal Cobalt (III) is surrounded by six nitrogen atomsoriginating from two coordinated ethylenediamines and twoazides resulting in an octahedral geometry. The bond lengths andbond angles for the title complex are comparable to those of [cis-Co(en)2(N3)2]NO3 and [cis-Co(en)2(N3)2]SCN. The Co–N bondlength is in the range of 1.955(3)–1.973(3) Å for nitrogen atom ofethylenediamine and in the range of 1.945(3)–1.964(3) Å for nitro-gen atoms of azide group in [cis-Co(en)2(N3)2]NO3. These values for

the [cis-Co(en)2(N3)2]SCN range from 1.922(16) to 1.996(17) Å andfrom 1.917(17) to 1.968(17) Å, respectively. The corresponding val-ues for the title complex salt range from 1.933(3) to 1.961(3) Å andfrom 1.934(3) to 1.939(3) Å, respectively. Also the N–N–N bond an-gle values of azide group for the [cis-Co(en)2(N3)2]NO3 are 174.7�and 177.1� and the values for [cis-Co(en)2(N3)2]SCN are 174.9�and 176.8�. These values for the title complex were 175.0� and175.4�, which showed a linear arrangement of the three nitrogenatoms in the coordinated azide groups.

The bond lengths and bond angles of the anion for the title com-plex salt were comparable with those of ionic saccharinates. Acomparison of bond lengths and bond angles of different bondsin the title complex cation and anion with the similar type of com-plexes in literature is given in Table 3.

Fig. 6. A view of the crystal structure showing the hydrogen bonding betweencations and anions (through second sphere coordinations). Thermal ellipsoidsrepresent 50% probability.

Table 4Hydrogen bonding parameters (Å, �) for [cis-Co(en)2(N3)2]C7H4SO3N.

D–H....A D–H H. . .A D. . .A \D–H. . .A

N1–H13. . .O3a 0.87(4) 2.35(4) 3.096(5) 144(3)N1–H14. . .O3b 0.93(3) 2.10(3) 2.928(4) 148(3)N2–H23. . .O1c 0.82(3) 2.29(3) 3.043(4) 154(3)N3–H34. . .O1c 0.84(4) 2.23(3) 3.024(4) 158(4)N4–H44. . .O3b 0.86(3) 2.05(4) 2.893(4) 163(3)

Symmetry transformations used to generate equivalent atoms.a 1 + x, 1 + y, z.b 1 � x, 1 � y, 1 � z.c 1 � x, 1 � y, 2 � z.

R. Sharma et al. / Journal of Molecular Structure 930 (2009) 88–94 93

On comparing the values of saccharinate anion in the title com-plex salt with neutral saccharin, we found that upon deprotonationof saccharin the following geometric changes take place in the an-ion as have been found by others [6] also.

– Lengthening of the C–O and S–O bonds;– shortening of the S–N bond;– decrease of the O–S–O angle;– increase of the C–S–N angle.

In the present structure, organic anions and the cations formalternate layers as shown in Fig. 6, linked together by NH. . .Ohydrogen bonds, whose structural parameters are reported inTable 4. These interactions involve the oxygen atoms O1 and O3of the saccharinate anion and three of the NAH hydrogen atomsof the ethylenediamine ligand of the cation. O3 of the saccharinateanion undergoes hydrogen bonding with three hydrogen atoms oftwo different [cis-Co(en)2(N3)2]+ cations, while a third cation is li-gated via two hydrogen bonds to the same anion. These interac-tions result in the formation of a three dimensional H-bondedstructure. In the solid state, these two ions form an intricate net-work of hydrogen bonds based on second-sphere coordinationwhich stabilizes the entire crystal lattice.

All these studies confirm the composition of the title complexsalt and the independent existence of discrete ions, i.e., [cis-Co(en)2(N3)2]+ and C7H4SO3N. The structure is stabilized by theelectrostatic forces of attraction and H-bonding interactions.

5. Conclusions

The complex salt [cis-Co(en)2(N3)2]C7H4SO3N has been synthe-sized and characterized by infrared, electronic, 1H and 13C NMRspectroscopic techniques. X-ray crystal structure determinationof the complex salt reveals the ionic structure. The structure con-sists of discrete [cis-Co(en)2(N3)2]+ and C7H4SO3N� ions. The studyshows the formation of supramolecular assembly featuring N–H. . .O hydrogen bonds. Thus the cation, [cis-Co(en)2(N3)2]+ provesto be a useful anion receptor for saccharinate anion.

Supplementary data

Crystallographic data for the structural analysis of the title com-pound has been deposited at the Cambridge Crystallographic DataCenter, 12 Union Road, Cambridge, CB2 1EZ, UK, and are availablefree of charge from the Director on request quoting the depositionnumber CCDC 615944 (Fax: +44 1223 336033, email: deposit@ccdc.cam.ac.uk).

Acknowledgement

The authors gratefully acknowledge the financial support ofUGC vide Grant No. F.12-38/2003(SR) dated 31-03-2003.

References

[1] J.L. Pieere, D. Baret, Bull. Soc. Chim. Fr. (1983) 367.[2] F. Vogetle, H. Siger, W.H. Muller, Top. Curr. Chem. 98 (1981) 43.[3] S.R. Gadre, C. Kolmel, I.H. Shrivastava, Inorg. Chem. 31 (1992) 2279.[4] F.P. Schmidtchen, M. Berger, Chem. Rev. 97 (1997) 1609.[5] A. Bianchi, K. Bowman-James, E. Garcia-Espana (Eds.), Supermolecular

Chemistry of Anions, WILEY-VCH, New York, 1997.[6] G. Jovanovski, Croatica Chem. Acta 73 (2000) 843.[7] K.M.A. Malik, S.Z. Haider, M.A. Hossain, M.B. Hursthouse, Acta Cryst. C 40

(1984) 1696.[8] N. Suzuki, H. Suzuki, Cancer Res. 55 (1995) 4253.[9] M.J. Coon, Proc. Int. Congr. Pharmacol. 6 (1975) 117.

[10] I.C. Munro, C.A. Modie, D. Krewski, H.C. Grice, Toxical. Appl. Pharmacol. 32(1975) 513.

[11] (a) T.V. Mitkina, N.F. Zakharchuk, D.Y. Naumov, O.A. Gerasko, D. Fenske, V.P.Fedin, Inorg. Chem. 47 (2008) 6748;(b) P. Comba, M. Kerscher, G.A. Lawrance, B. Martin, H. Wadepohl, S.Wunderlich, Angew. Chem. Int. Ed. 47 (2008) 4740;(c) R.P. Sharma, A. Singh, V. Ferretti, P. Venugopalan, J. Mol. Struct. 918 (2009)123.

[12] (a) D.A. Buckingham, J.P. Collman, D.A.R. Happer, L.G. Marzilli, J. Am. Chem.Soc. 89 (1967) 2772;(b) L.J. Charbonniere, G. Bernardinelli, C. Pinguet, A.M. Sargeson, A.F. Williams,J. Chem. Soc. Chem. Commun. (1994) 1419.

[13] E.M.N. Hamilton, S.A.S. Gropper, In the Biochemistry of Human Nutrition, WestPubl. Co., New York, 1987. P. 298.

[14] H.M. Helis, P. de. Meester, D.J. Hodgson, J. Am. Chem. Soc. 99 (1976) 3309.[15] (a) P. Chen, J. Li, F. Duan, J. Yu, R. Xu, R.P. Sharma, Inorg. Chem. 46 (2007) 6683;

(b) R. Xu, W. Pang, J. Yu, Q. Huo, J. Chen, Chemistry of Zeolites and RelatedPorous Materials Synthesis and Structure, John Wiley and Sons, Singapore,2007.

[16] W.G. Jackson, C.M. Begbie, Inorg. Chim. Acta 60 (1982) 115.[17] J.P. Collman, P.W. Schneider, Inorg. Chem. 5 (1966) 1380.[18] R.G. Pearson, P.M. Henry, F. Basolo, J. Am. Chem. Soc. 79 (1957) 5378.[19] R.J. Restivo, G. Ferguson, R.W. Hay, D.P. Piplani, J. Chem. Soc. Dalton Trans.

(1978) 1131.[20] J. Cho, J.C. Kim, A.J. Lough, Inorg. Chem. Commun. 6 (2003) 284.[21] M.E. Kastner, D.A. Smith, J.N. Cooper, A.G. Kuzmission, T. Tyree, M. Yearick,

Inorg. Chim. Acta 158 (1989) 185.[22] V.M. Padmanabhan, R. Balasubramanian, K.V. Murlidharan, Acta Cryst. B24

(1968) 1638.[23] P.J. Staples, M.L. Tobe, J. Chem. Soc. (1960) 4812.[24] (a) B.N. Figgis, C.L. Raston, R.P. Sharma, A.H. White, Aust. J. Chem. 31 (1978)

2437;(b) R.P. Sharma, V. Gupta, K.K. Bhasin, E.R.T. Tiekink, J. Coord. Chem. 33 (1994)117;(c) R.P. Sharma, V. Gupta, K.K. Bhasin, M. Quiros, J.M. Salas, Acta Cryst. C50(1994) 1875;(d) R.P. Sharma, K.K. Bhasin, E.R.T. Tiekink, J. Coord. Chem. 36 (1995) 225;(e) R.P. Sharma, K.K. Bhasin, E.R.T. Tiekink, Acta Cryst. C52 (1996) 2140;(f) D.S. Gill, V. Pathania, B.K. Vermani, R.P. Sharma, Z. Phys. Chemie. 1 (2003)217.

94 R. Sharma et al. / Journal of Molecular Structure 930 (2009) 88–94

[25] (a) R.P. Sharma, R. Sharma, R. Bala, U. Rychlewska, B. Warzajti, V. Ferretti, J.Mol. Struct. 753 (2005) 82;(b) R.P. Sharma, R. Sharma, R. Bala, M. Quiros, J.M. Salas, J. Coord. Chem. 56(2003) 1581;(c) R. Sharma, R.P. Sharma, R. Bala, L. Pretto, V. Ferretti, J. Mol. Struct 800(2006) 93;(d) R.P. Sharma, R. Sharma, R. Bala, K.N. Singh, L. Pretto, V. Ferretti, J. Mol.Struct. 784 (2006) 109;(e) R.P. Sharma, R. Sharma, R. Bala, A.D. Bond, Acta Cryst. C61 (2005) m272.

[26] J.N. Cooper, D.A. Smith, M.E. Kastner, J. Chem. Edu. 66 (1989) 968.[27] A.I. Vogel, A Text Book of Quantitative Inorganic Analysis, Longmans, London,

1961.[28] G.M. Sheldrick, SHELXL97 and SHELXS97, University of Gottingen, Germany,

1997.[29] S. R. Hall, Du Boulay, Xtal-GX, University of Western Australia, Australia

(1997).[30] S.S. Massoud, Polyhedron 13 (1994) 3127.[31] K. Nakamoto, Infrared and Raman Spectra of Inorganic and Coordination

Compounds’, fourth ed., John Wiley & Sons, New York, 1986.

[32] C.A. Johns, K.M.A. Malik, Polyhedron 21 (2002) 395.[33] P. Hendry, A. Ludi, Adv. Inorg. Chem. 35 (1990) 117.[34] I.R. Lantzke, D.W. Watts, Aust. J. Chem. 20 (1967) 35.[35] E. Kleinpeter, D. Strohl, G. Jovanovski, B. Soptrajanov, J. Mol. Struct. 246 (1991)

185.[36] S.W. Ng, Acta. Cryst. C54 (1998) 649.[37] E.W. Ainscough, E.N. Baker, A.M. Brodie, R.J. Cresswell, J.D. Ranford, J.M.

Waters, Inorg. Chim. Acta 172 (1990) 185.[38] P. Naumov, S. Cakir, I. Bulut, E. Bicer, O. Cabir, G. Jovanovski, A.R. Ibrahim, A.

Usman, H-Kun Fun, S. Chaatrapromma, S.W. Ng, Main Group Met. Chem. 25(2002) 175.

[39] P. Naumov, G. Jovanovski, J. Coord. Chem. 54 (2000) 63.[40] B. Schulze, K. Illgen, J. Prakt. Chem. (1997) 339.[41] J.M. Li, Y.X. Ke, Q.M. Wang, X.T. Wu, Cryst. Res. Technol. 32 (1997) 481.[42] R. Hargens, W. Min, R.C. Henny, Inorg. Synth. 14 (1973) 78.[43] P. Naumov, G. Jovanovski, Spectrochim. Acta 56 (2000) 1305.[44] S.W. Ng, C. Wei, V.G.K. Das, T.C.W. Mak, J. Organomet. Chem. 373 (1989) 21.[45] G. Jovanovsky, A. Hergold-Brundie, O. Grupce, D. Matkovic-Calogovic, J. Chem.

Crystallogr. 29 (1999) 233.