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Inorganica Chimica Acta 360 (2007) 3719–3726

Solid state and solution NMR, X-ray and antimicrobialstudies of 1:1 and 2:1 complexes of silver(I) cyanide with

alkanediamine ligands

Anvarhusein A. Isab a,*, Mohamed I.M. Wazeer a, Mohammed Fettouhi a,Bassem A. Al-Maythalony a, Abdul Rahman Al-Arfaj a, Norah O. Al-Zamil b

a Department of Chemistry, King Fahd University of Petroleum and Minerals, Dhahran 31261, Saudi Arabiab Department of Chemistry, Girls’ College, Dammam, Saudi Arabia

Received 23 January 2007; received in revised form 22 April 2007; accepted 24 April 2007Available online 30 April 2007

Abstract

Several complexes of AgCN with alkanediamine ligands (where the ligands are ethylenediamine, propane-1,3-diamine, butane-1,4-diamine, N,N 0-dimethyl-ethylenediamine, N,N 0-di-iso-propyl-ethylenediamine, etc.) have been synthesized and structurallycharacterized. In these species, alkanediamine ligands act as chelating ligands. The X-ray structure of the complex cyano-(N,N 0-di-iso-propyl-ethylenediamine)–silver(I) was determined. These complexes have been also characterized by IR, solution aswell as solid-state NMR studies. There are two types of IR absorptions observed for mono and dinuclear complexes. Forthe mono nuclear complexes, a sharp CN band is observed between 2111 and 2131 cm�1 range, whereas for binuclear complexesthe bands are in the range 2136–2140 cm�1. The effect of the size of the ligands as well as their substituents is discussed. Theantimicrobial activity studies of AgCN and its complexes show that the former exhibits substantial antibacterial activities com-pared to its complexes.� 2007 Elsevier B.V. All rights reserved.

Keywords: AgCN–alkanediamine complexes; CPMAS NMR studies; X-ray crystal structure; Antimicrobial activity

1. Introduction

Applications of transition metal cyanides are wide-spread in chemistry, with recent interest in such diverseareas as molecular magnetism [1–4] and the synthesis ofporous supramolecular assemblies [5–7]. In 1999, Bow-maker et al. published powder neutron diffraction struc-tures of AuCN and AgCN and found that both systemsexist as ‘‘infinite’’ linear chains of alternating metal andcyanide moieties. Silver cyanide was found to be transla-tionally disordered, with adjacent chains displaced alongtheir long axis relative to each other [8].

0020-1693/$ - see front matter � 2007 Elsevier B.V. All rights reserved.

doi:10.1016/j.ica.2007.04.036

* Corresponding author. Fax: +966 3 860 4277.E-mail address: aisab@kfupm.edu.sa (A.A. Isab).

The coordination chemistry of alkanediamines is a sub-ject of interest from different points of view [5–7,9]. Thesebidentate ligands can adopt either a bridging or chelatingbonding mode. The interaction of Ag(I) with such r-donorligands was extensively studied by Pretsch et al. [10]. It wasfound that the chelate bonding mode was observed for thetwo-carbon alkane chains while the longer three and four-carbon chain diamines adopt the bridging mode.

In this paper, we present the results of the synthesis,solution and solid-state NMR studies, IR spectra and theantimicrobial studies of three new complexes along withthe X-ray structure of the complex cyano(N,N 0-di-iso-pro-pylethylenediamine)–silver(I). The NMR and antimicrobialstudies were performed on a series of other Ag(I)–alkanedi-amine complexes.

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2. Experimental

2.1. General

Reagents and solvents were used as received from com-mercial sources. The synthesized compounds were identi-fied by elemental analysis, IR and NMR spectroscopytechniques (see Table 1).

The following abbreviations are used: ethylenediamine(en), propane-1,3-diamine (pn), butane-1,4-diamine (bn),N-iso-propylethylenediamine (N-i-Pr-en), N,N 0-dimethyl-ethylenediamine (N,N 0-Me2-en), N,N 0-di-iso-propylethyl-enediamine (N,N 0-i-Pr2-en).

2.2. Synthesis

N,N 0-(ethane-1,2-diamine)–cyanosilver(I), [Ag(CN)-(en)], l-(propane-1,3-diamine)-di-[cyanosilver(I)] [(Ag-

Table 1Elemental analyses of the AgCN–alkanediamine complexes

Complex Found (Calc.) (%) M.p.(�C)C H N

AgCN-en 19.09 (18.57) 4.422 (4.16) 20.71 (21.66) 102–103[(AgCN)2-pn] 18.00 (17.56) 3.11 (2.95) 16.55 (16.39) 94–95[(AgCN)2-bn] 21.25 (20.25) 3.98 (3.40) 16.42 (15.74) 123–124[AgCN(N,N0-i-

Pr2-en)]37.92 (38.86) 7.33 (7.25) 16.01 (15.11) 132–135

[AgCN(N,N0-Me2-en)]

28.02 (27.05) 5.88 (5.45) 19.81 (18.92) 111–113

Table 2IR frequencies (m (cm�1)) of AgCN–alkanediamine complexes

Complex m(CN) from AgCN

AgCN 2139 (s)AgCN-en 2114 (s)[(AgCN)2-pn] 2140 (s)[(AgCN)2-bn] 2136 (s)[AgCN(N-i-Pr-en)] 2131 (w)[AgCN(N,N0-i-Pr2-en)] 2111 (s)

Table 31H and 13C NMR chemical shifts of AgCN–alkanediamine complexes in DM

Species N–H 13C–N C-1

en 45.05[AgCN-en] 2.59 143.90 41.87pn 39.86[(AgCN)2-pn] 3.46 142.57 40.71bn 42.15[(AgCN)2-bn] 3.49 142.21 42.74N-i-Pr-en 50.22[AgCN(N-i-Pr-en)] 144.68 48.88N,N0-i-Pr2-en 48.83[AgCN(N,N0-i-Pr2-en)] 3.67 144.41 49.12N,N0-Me2-en 51.44[AgCN(N,N0-Me2-en)] 142.49 50.41

CN)2-pn] and l-(butane-1,4-diamine)-di-[cyanosilver(I)],[(AgCN)2-bn] were prepared as described in the literature[10].

The three new complexes (N,N0-dimethylethylenediamine)–cyanosilver(I), [AgCN(N,N0-Me2-en)], (N,N0-di-iso-propyle-thylenediamine)–cyanosilver(I), [AgCN(N,N0-i-Pr2-en)] and(N-iso-propylethylenediamine)–cyanosilver(I), [AgCN(N-i-Pren)] were prepared according to the following generalprocedure: 400 mg (3 mmol) AgCN were mixed with3 mmol of the ligand in 50 ml of acetonitrile. The mixturewas refluxed for 4 h, concentrated and then let to crystallizein the refrigerator at 4 �C. Subsequently the solid was col-lected and dried. The percentage yield was approximately80%, 50% and 50%, respectively, for the three complexesbased on AgCN.

2.3. IR studies

The solid-state IR spectra of the ligands and theircyanosilver(I) complexes were recorded on a Perkin–ElmerFTIR 180 spectrophotometer using KBr pellets over therange 4000–400 cm�1. The selected IR frequencies aregiven in Table 2.

2.4. Solution NMR measurements

All NMR measurements were carried out on a JeolJNM-LA 500 NMR spectrophotometer at 297 K using0.10 M solution of the complexes in DMSO-d6. 13CNMR spectra were obtained at 125.65 MHz with 1Hbroadband decoupling. The spectral conditions were: 32kdata points, 0.967 s acquisition time, 1.00 s pulse delayand 45� pulse angle. The NMR chemical shifts are givenin Table 3 according to Scheme 1.

The 107Ag NMR was obtained at 20.13 MHz using10 mm low frequency probe with 9.1 M aqueous AgNO3

as an external reference. The spectral conditions were:1.02 s acquisition time, 6.0 s delay time, 45� pulse angleand approx. 3000 scans. For all complexes, 107Ag NMRwas recorded using 0.05 M solution in DMSO-d6 [11].The NMR chemical shifts are given in Table 4.

SO-d6

C-2 C-3 C-4 C-5

37.3335.81 40.0131.1829.8948.679 42.25 23.1147.38 41.31 31.069 23.26347.58 23.1046.93 23.3436.5050.41

CH21

CH21

NHNH

Ag

NC

AgCN-en

2

3NH

AgCN

1NH

AgNC

(AgCN)2-pn

NH1

2

2

1NH

AgAg CN

NC

(AgCN)2-bn

12

NHN

Ag

CN

3

CH34

CH35

AgCN(N-i-Pr-en)

11

NN

Ag

NC

2

CH33

CH33

2

CH33

CH33

AgCN(N,N'-i-Pr2-en)

N N

Ag

CN

CH32

CH32

11

AgCN(N,N'-Me2-en)

Scheme 1.

Table 4107Ag NMR chemical shifts of AgCN–alkanediamine complexes inDMSO-d6

Species 107Ag

[AgCN-en] 724[(AgCN)2-pn] 583[(AgCN)2-bn] 566[AgCN(N,N0-i-Pr2-en)] 631[AgCN(N,N0-Me2-en)]

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2.5. Solid-state NMR

Natural abundance 13C solid-state NMR spectra wereobtained on a JEOL LAMBDA 500 spectrometer operat-ing at 125.65 MHz (11.74 T), at ambient temperature of25 �C. Samples were packed into 6 mm zirconium oxiderotors. Cross-polarization and high power decoupling wereemployed. Pulse delay of 7.0 s and a contact time of 5.0 mswere used in the CPMAS experiments. The magic anglespinning rates were from 2 kHz to 5 kHz. Carbon chemicalshifts were referenced to TMS by setting the high frequencyisotropic peak of solid admantane to 38.56 ppm. Natural

abundance 15N spectra were also recorded on the abovemachine, using a contact time of 5 ms and a pulse delayof 10 s. The magic angle spinning rates were between4000 Hz and 5000 Hz. The chemical shift of nitrogen wasinitially referenced with respect to liquid NH3, by settingthe 15N peak in enriched solid 15NH4Cl to 40.73 ppm [12]and then converted to the standard nitromethane by a shiftof �380.0 ppm [13] for ammonia. The solid NMR data aregiven in Table 5.

Both the 15N spectra and 13C spectra, containing spin-ning side-band manifolds, were analyzed using a programHBA [14] based on Maricq and Waugh [15] which developedat Dalhousie University, Canada, and University of Tubin-gen, Germany.

Solid-state NMR data show more sensitivity to coordi-nation geometry, which is expected from the removal ofthe solvent effects, fluxional processes and other averagingprocesses that may be present in the solution state (Figs. 1and 2). It has the added advantage that it provides the threeprincipal components of the shielding tensor, rather thanjust the average value observed in solution spectra. Unlikesolution chemical shifts, solid-state NMR results can becorrelated directly with crystallographic structure determi-nations when available, and structural predictions can bemade in the absence of crystallographic data.

2.6. X-ray data collection and structure determination

A crystal of the complex cyano(N,N 0-di-iso-propylethy-lenediamine)–silver(I) was mounted on a glass fiber. Dif-fraction data were recorded on a Bruker AXS SMARTAPEX system equipped with a graphite-monochromatizedMo Ka radiation (k = 0.71073 A). The data were collectedusing SMART [16]. The data integration was performed usingSAINT [17]. An empirical absorption correction was carriedout using SADABS [18]. The structure was solved with thedirect methods and refined by full-matrix least-squaremethods based on F2, using the structure determinationand graphics package SHELXTL [18] based on SHELX-97[20]. The amino group hydrogen atoms were located inthe difference Fourier maps. All other hydrogen atomswere placed at calculated positions. The crystallographicdata are given in Table 6. Selected bond lengths and anglesare given in Tables 7 and 8. The drawing of the molecularstructure with the atomic labeling scheme is given in Fig. 3.

Table 5Solid-state 13C, and 15N isotropic chemical shifts (diso) and principal shielding tensors (rxx)a of complexes AgCN–alkanediamine

L Nucleus diso r11 r22 r33 Dr g Other

AgCNb 13C 157 �276 �276 79 355 0.0015N �131 �14 �14 421 435 0.00

[AgCN(N,N0-i-Pr2-en)]c 13C 149 �261 �250 60 323 0.05 50, 27 (CH2)15N �93 �74 �74 426 501 0.00 �330 (NH2)

[(AgCN)2-bn]d 13C 150 �261 �261 70 333 0.00 44, 42, 29, 27 (CH2)15N �95 �71 �71 427 498 0.00 �302 (NH2)

a Isotropic shielding, ri = (r11 + r22 + r33)/3; Dr = r33 � 0.5(r11 + r22); g = 3(r22 � r11)/2Dr.b Reference [27].c JAg–C = 220 Hz.d JAg–C = 194 Hz.

Fig. 1. 13C CPMAS NMR spectrum of [AgCN(N,N 0-i-Pr2-en)]. The peaks marked * denote the center band of CN, ‘a’ denotes CH2 and ‘b’ denotes i-Pr.

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2.7. Antibacterial activity

Antimicrobial activity was measured as described in theliterature [21,22]. It was evaluated by the minimum inhibi-tory concentration (MIC) on three microorganisms,namely Pseudomonas aeruginosa (P. aeruginosa), Fecal

streptococcus (FS) and Escherichia coli (E. coli) and on agroup of organisms Heterotrophic Plate Counts (HPC).HPC is a standardized means of determining the densityof aerobic and facultative anaerobic heterotrophic bacteriain water/wastewater. It is a group of bacteria and not a sin-gle strain.

These bacteria/group of bacteria were isolated and cul-tured from domestic wastewater (Al-Khobar WastewaterTreatment Plant at Al-Azizia, Saudi Arabia) in which avariety of pathogens and other microorganisms are pres-ent. Each analysis was carried out in duplicate to maintainthe maximum accuracy. Dosage of reached a maximumdose of 1000 lg/ml was used as a stopping criterion. Astock solution of 1000 lg/ml was used to prepare consecu-tive dilution having concentration difference of 25 lg/ml.The AgCN–alkanediamine complexes are insoluble inwater but these bioactivities are done in water. Therefore,two runs are done, one in which the complex was dissolved

*

a

Fig. 2. 15N CPMAS NMR spectrum of [AgCN(N,N 0-i-Pr2-en)]. The center band of CN is denoted by an * and the NH peak is denoted by ‘a’.

Table 6Crystal and structure refinement data [AgCN(N,N 0-i-Pr2-en)]

Empirical formula C9H20AgN3

Formula weight 278.15Temperature (K) 296Wavelength (A) 0.71073Crystal system monoclinicSpace group P21/cUnit cell dimensions

a (A) 8.883(1)b (A) 12.425(2)c (A) 11.406(2)b (�) 101.442(2)

Volume (A3) 1233.9(3)Z 4Dcalc (g cm�3) 2.34h Range for data collection (�) 2.34–28.28Limiting indices �11 6 h 6 11, �15 6 k 6 15,

�15 6 l 6 15Data/parameters 2351/130Goodness-of-fit on F2 1.030Final R indices [I > 2r(I)] R1 = 0.0334, wR2 = 0.0757

Table 7Selected bond lengths (A) and bond angles (�)

Bond lengths (A)

Ag1–C1 2.058(3) C2–N2 1.476(4)Ag1–N3 2.351(3) C5–N2 1.465(4)Ag1–N2 2.352(2) C6–N3 1.459(4)C1–N1 1.130(4) C7–N3 1.478(4)

Bond angles (�)

C1–Ag1–N3 139.7(1) C5–N2–C2 114.7(3)C1–Ag1–N2 142.9(1) C6–N3–C7 114.2(3)N3–Ag1–N2 76.02(9) C5–N2–Ag1 107.6(2)N1–C1–Ag1 179.5(3) C2–N2–Ag1 119.4(2)N2–C2–C3 108.9(3) C6–N3–Ag1 107.0(2)N2–C2–C4 110.5(3) C7–N3–Ag1 119.4(2)

Table 8Hydrogen bond distances (A) and angles (�)

D–H� � �A D–H (A) H� � �A (A) D� � �A (A) D–H� � �A (�)

N3–H3� � �N1 (i) 0.82(3) 2.38(3) 3.158(4) 158(3)N2–H1� � �N1 (ii) 0.81(3) 2.53(3) 3.281(4) 154(3)

Symmetry codes: (i) �x + 1, 0.5 + y, �z + 0.5; (ii) �x + 1, �y, �z + 1.

A.A. Isab et al. / Inorganica Chimica Acta 360 (2007) 3719–3726 3723

in DMSO and then the bioactivities are measured in waterand the other run was done in water. The results are sum-marized in Table 9.

3. Results and discussion

3.1. Vibrational studies

The very informative parameter of cyanide complexes isthe cyanide stretching frequency. The CN stretching mode

of the bridging cyanide groups in silver(I) cyanide, which iscomposed of linear –AgCN–AgCN– chains, is observed at2164 cm�1 [8,9]. It appears at higher wavenumbers than thestretching vibration of the isolated triatomic AgCN mole-cule, which has been calculated in the course of a theoret-ical study at m(CN) = 2094 cm�1 [23]. The lowestfrequencies m(CN) known for salt-like cyanides such as

Fig. 3. Molecular structure of [AgCN(N,N 0-i-Pr2-en)]. Hydrogen atomshave been omitted for clarity.

3724 A.A. Isab et al. / Inorganica Chimica Acta 360 (2007) 3719–3726

KCN are in the range 2080–2070 cm�1 [24]. In the presentstudy, this useful tool is applied to characterize silver(I)cyanide adducts and to distinguish between the mononu-clear and binuclear silver(I) cyanide complexes by focusingon the CN stretching mode.

The stretching frequency of the C„N bond has beenassigned to 2114 cm�1 in [AgCN-en]. It is shifted to highervalues in [(AgCN)2-pn] (m = 2140 cm�1) and [(AgCN)2-bn]m = 2136 cm�1. This trend is due to the lower coordinationnumber of silver(I) in the binuclear complexes. The assign-ment of m(CN) is in good agreement with that of [(AgCN)2-en] [25], which shows m(CN) band at 2144 cm�1.

Free CN� stretching band in KCN occurs at 2084 cm�1.No band in this region is observed in the complexes understudy, so it can be concluded that there is no exchange withthe KBr from the disc.

3.2. Solution NMR studies

Scheme 1 shows the assignments of the various 13CNMR resonances of the complexes. The 13C NMR indi-cates that mononuclear complexes show a chemical shiftof 13CN� in the range of 144–145 ppm, e.g. [Ag(CN)(en)],[Ag(CN)(N,N 0-i-Pr2-en)], etc. whereas dinuclear complexes

Table 9Antimicrobial activity for Heterotrophic Plate Counts (HPC), Pseudomonas ae

(E. coli)

Test organism AgCN(water)

AgCN(DMSO)

AgCN-en(water)

AgCN-en(DMSO)

HPC 250 250 625 600P. aeruginosa 175 150 375 350FS 100 75 400 400E. coli 25 <25 225 150

like [(AgCN)2-pn] and [(AgCN)2-bn] show 13CN� reso-nance in the range of 142–143 ppm. This is an interestingobservation because we already published [26] mononu-clear complexes of Ag13C15N with imidazolidine-2-thione(Imt) and its derivatives, in which, the chemical shift rangefor the mononuclear Ag13C15N bound to thione is between143 and 144 ppm. This slight difference may be due to thetrans ligand such en and Imt. There is no significant differ-ence observed between free and bound diamine ligands toAgCN and therefore are not discussed here.

The chemical shift of 13C NMR resonances particularlythe cyanide group bonded to AgCN shows the up-fieldtrend as we go from [Ag(CN)(en)], 143.9 ppm;[(AgCN)2(pn)], 142.57 ppm, to [(AgCN)2(bn)],142.21 ppm. This can be interpreted as the increase of thep-back bonding from silver to the ligand which leads thea more shielded cyanide group. As we move from mono-nuclear to dinuclear complexes, we have less angularexpansion resulting in stronger interaction and greater pback donation in the two-coordinated dinuclear complexes.

In 107Ag NMR, the silver signal for the [AgCN(L)] com-plexes was observed to be more than 650 ppm downfieldwith respect to AgNO3 in D2O, upon complexation ofAgCN with thiones. The 107Ag chemical shifts for en, pnand bn complexes are 724, 583 and 566, respectively. Thisindicates that as we shift from the mono-nuclear to thedinuclear complex the r-donation from the diamine ligandto the metal increases, which causes more shielding of silveratom and hence upfield shift. A similar trend was observedfor 107Ag chemical shifts for Imt, diazinane-2thione (Diaz)and diazipane-2-thione (Diap) complexes, are 640, 626 and629, respectively [26]. The very large shifts in the 107AgNMR spectra in all these complexes provides clear evi-dence for the binding of alkanediamines to silver(I).

The study provides useful information about the natureof bonding in silver(I) complexes. We have shown thatLAgCN complexes are stable in solution, unlike LAuCNcomplexes [27–29], which dissociate in solution (whereL = thione and or selone containing ligands). The chemicalshifts for different complexes presented here are useful,especially if the 107Ag NMR is used to study silver(I) com-plexes with nitrogen containing biological ligands.

3.3. Solid NMR studies

The carbon-13 NMR spectrum and the nitrogen-15NMR spectrum of solid [Ag13C15N(N,N 0-i-Pr2-en)]

ruginosa (P. aeruginosa) and Fecal streptococcus (FS) and Escherichia coli

(AgCN)2-pn(water)

(AgCN)2-pn(DMSO)

(AgCN)2-bn(water)

(AgCN)2-bn(DMSO)

>1000 975 >1000 950850 825 900 875725 725 800 800650 625 750 750

A.A. Isab et al. / Inorganica Chimica Acta 360 (2007) 3719–3726 3725

acquired at 11.7 T is shown in Figs. 1 and 2, respectively.The direct dipolar coupling interactions between the 13Cand 15N nuclei and between 13C and 109/107Ag nuclei areaveraged to zero under the experimental conditions. Onlythe scalar coupling between 109Ag (48.18%) and 13C andbetween 107Ag (51.82%) and 13C are resolved in the spec-trum. The two scalar coupling constants are similar dueto the fact that the two magnetogyric ratios of the two sil-ver isotopes differ only by about 15%. A similar scalar cou-pling constant was also reported for silver cyanide andhence the doublet is not due to different carbon environ-ments in the solid state. The spinning side-band manifoldintensity patterns were analyzed by the method of Herzfeldand Berger and the results are shown in Table 5. The axialsymmetry of the chemical shift tensor implies a linear envi-ronment at carbon. The data from the published results forsilver cyanide is included for comparison [30]. However,the solid-state silver cyanide exists as linear polymericchains with about 30% of the silver sites being disorderedwith respect to the way the silver is bonded to two carbonsor two nitrogens, rather than bonded to one carbon andone nitrogen. The disorder was shown [30] to display asym-metric doublets in the 13C MAS spectrum. Our spectrashow symmetric doublets and hence disorder and thepolymeric structure are ruled out (see Figs. 1 and 2). Thisis confirmed by the single crystal X-ray study on[AgCN(N,N 0-i-Pr2-en)] (Fig. 3).

The observation of scalar coupling between silver andcarbon indicates that there is no dynamic disorder as inthe case of some alkali metal cyanides, where the cyanogroups are in a state of dynamic disorder [31].

3.4. X-ray crystal structure of the complex [AgCN(N,N 0-i-

Pr2-en)]

The Ag(I) ion is bonded to two nitrogen atoms of theethylene diamine moiety and a carbon atom of the cyanideion in a distorted trigonal geometry. The two Ag–N bondlengths average to 2.352(2) A and the chelate angle N2–Ag1–N3 is 76.02(9)�. These geometrical values are similarto those reported for the mononuclear complex [Ag(CN)(en)] from low temperature (173(2) K) X-ray data: (Ag–C1: 2.061(7) A; Ag1–N2: 2.283(6) A; Ag1–N3: 2.355(6) A;N3–Ag1–N2 is 76.7(2)�) [10]. The chelate conformation is(�)-synclinal with a torsion angle of �64.42�. The Ag–Nbond distances in this three-coordinate complex as wellas those reported in Ref. [10] are significantly longer thanthose found in the two-coordinate [NC–Ag–NH2–] com-plexes. Interestingly, the Ag–C bond, involving p interac-tion, does not show significant change in the two-coordination spheres while the sigma donation of theamino groups is weakened in the trigonal coordination.This later fact corroborates the NMR chemical shift trendobtained in the present study. The shortest Ag� � �Ag dis-tance (3.461 A) is significantly longer than the sum of thevan der Waals radii of Ag(I) ions (3.44 A) [32]. Moleculesof the complex are engaged in intermolecular hydrogen

bonding between the cyanide N atom and N–H groups giv-ing rise to a 2D hydrogen bonding scheme (Table 8).

3.5. Antibacterial activity studies

The results of the bioactivity studies are given in Table 9.The AgCN itself shows significant antimicrobial activitycompared to its alkanediamine complexes. It is interestingto note that all four tests HPC, P. aeruginosa, FS andE. coli increase as the size of alkanediamine increases. Thisindicates that the activity follows [AgCN-en] > [(AgCN)2-pn] > [(AgCN)2-bn]. These are the first studies of its kindand therefore there is no comparison with the literaturevalues.

4. Summary and conclusion

We have isolated new alkanediamine silver(I) cyanidecomplexes. Their mononuclear nature is shown by theX-ray structure of the complex [AgCN(N,N 0-i-Pr2-en)]and corroborated by solid-state NMR. In this series ofcompounds, the substituted ethylenediamine ligands adopta chelate-like coordination of silver(I). Antimicrobial activ-ity studies of AgCN and its complexes show that AgCNitself exhibits substantial antibacterial activity comparedto its alkanediamine complexes.

Acknowledgement

This research was supported by the KFUPM ResearchCommittee under Project No. SABIC 2006-08.

References

[1] J.J. Sokol, M.P. Shores, J.R. Long, Angew. Chem., Int. Ed. Engl. 40(2001) 236.

[2] S.-W. Zhang, D.-G. Fu, W.-Y. Sun, Z. Hu, K.-B. Yu, W.-X. Tang,Inorg. Chem. 39 (2000) 1142.

[3] H. Vahrenkamp, A. Geiss, G.N. Richardson, J. Chem. Soc., DaltonTrans. (1997) 3643.

[4] S. Vaucher, E. Dujardin, B. Lebeau, S.R. Hall, S. Mann, Chem.Mater. 13 (2001) 4408.

[5] B.W. Pfennig, V.A. Fritchman, K.A. Hayman, Inorg. Chem. 40(2001) 255.

[6] C.A. Bignozzi, R. Argazzi, O. Bortolini, F. Scandola, A. Harriman,New J. Chem. 20 (1996) 731.

[7] D.J. Chesnut, D. Plewak, J. Zubieta, J. Chem. Soc., Dalton Trans.(2001) 2567.

[8] (a) G.A. Bowmaker, B.J. Kennedy, J.C. Reid, Inorg. Chem. 37 (1998)3968;(b) G.A. Bowmaker, P.C. Effendy Junk, B.W. Skelton, A.H. White,Z. Naturforsch. B 59 (2004) 1277.

[9] (a) G.A. Bowmaker, J.C. Effendy Reid, C.E.F. Rickard, B.W.Skelton, A.H. White, J. Chem. Soc., Dalton Trans. (1998) 2139;(b) G.A. Bowmaker, C. Pettinari, B.W. Skelton, N.A. Vigar, A.H.White, Z. Anorg. Allg. Chem. 633 (2007) 415.

[10] T. Pretsch, H. Hartl, Inorg. Chim. Acta 358 (2005) 1179.[11] S. Ahmad, A.A. Isab, Inorg. Chem. Commun. 5 (2002) 355, and

references therein.[12] S. Hayashi, K. Hayamizu, Bull. Chem. Soc. Jpn. 64 (1991) 688.

3726 A.A. Isab et al. / Inorganica Chimica Acta 360 (2007) 3719–3726

[13] W. Kemp, NMR in Chemistry, Macmillan Education Ltd., London,1986.

[14] K. Eichele, R.E. Wasylischen, WSolid1 NMR Simulation Package,Version 1.4.4, Dalhousie University and University of Tubingen,Canada and Germany, 2001.

[15] M. Maricq, J. Waugh, J. Chem. Soc. 70 (1979) 3300.[16] SMART APEX Software (5.05) for SMART APEX detector, Bruker Axs

Inc., Madison, WI, USA, 1998.[17] SAINT Software (5.0) for SMART APEX detector, Bruker Axs Inc.,

Madison, WI, USA, 1998.[18] G.M. Sheldrick, SADABS: Program for Empirical Absorption correc-

tion of Area detector Data, University of Gottingen, Gottingen,Germany, 1996.

[18] G.M. Sheldrick, SHELXTL V5.1 Software, Bruker AXS, Inc., Madison,WI, USA, 1997.

[20] G.M. Sheldrick, SHELX-97: Program for crystal structure analysis,University of Gottingen, Germany, 1997.

[21] K. Nomiya, A. Yoshizawa, K. Tsukagoshi, N.C. Kasuga, S.Hirakawa, J. Watanabe, J. Inorg. Biochem. 95 (2003) 208.

[22] N.C. Kasuga, K. Sekino, M. Ishikawa, A. Honda, M. Yokoyama, S.Nakano, N. Shimada, C. Koumo, K. Nomiya, J. Inorg. Biochem. 96(2003) 298.

[23] F.C. Feldkamp, G. Frenking, Organometallics 12 (1993)4613.

[24] L.J. Bellamy, The Infrared Spectra of Complex Molecules, third ed.,Wiley, New York, 1975, p. 390.

[25] K. Brodersen, T. Kahlert, Z. Anorg. Allg. Chem. 348 (1966)273.

[26] W. Ashraf, S. Ahmad, A.A. Isab, Transition Met. Chem. 29 (2004)400.

[27] A.J. Canumalla, N. Al-Zamil, M. Philips, A.A. Isab, C.F. Shaw III, J.Inorg. Biochem. 85 (2001) 67.

[28] S. Ahmad, A.A. Isab, Inorg. Chem. Commun. 4 (2001) 362.[29] S. Ahmad, A.A. Isab, A.R. Al-Arfaj, A.P. Arnold, Polyhedron 21

(2002) 2099.[30] D.L. Bryce, R.E. Wasylishen, Inorg. Chem. 41 (2002) 4131.[31] R.E. Wasylischen, K.R. Jeffrey, J. Chem. Phys. 78 (1983) 1000.[32] A. Bondi, J. Phys. Chem. 68 (1964) 441.