Synthesis, spectral characterization, catalytic andbiological studies of new Ru(II) carbonyl Schiff base complexes of active amines

doi:10.4236/ns.2011.37076

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Vol.3, No.7, 542-550 (2011) Natural Science

http://dx.doi.org/10.4236/ns.2011.37076

Synthesis, spectral characterization, catalytic and

biological studies of new Ru(II) carbonyl Schiff base

complexes of active amines

Vellalapalayam Vangaiannan Raju1, Kugalur Palanisamy Balasubramanian1,

Chinnasamy Jayabalakrishnan2, Vaiapuri Chinnusamy2*

1Department of Chemistry, Gobi Arts & Science College, Gobichettipalayam, India;

2PG Department of Chemistry, Sri Ramakrishna Mission Vidyalaya College of Arts & Science, Coimbatore, India;

*Corresponding Author: [email protected]

Received 23 December, 2010; revised 22 March, 2011; accepted 10 April, 2011.

ABSTRACT

The synthesis and characterization of several

hexa–coordinated Ru(II) complexes of the type

[Ru(CO)(B)(L)] (B = PPh3/AsPh3/py/pip; L = di-

basic tetradentate ligand derived from the con-

densation of isatin with diamines) were reported.

IR, electronic, 1H-NMR, 31P-NMR of the com-

plexes are discussed. An octahedral geometry

has been tentatively proposed for all these

complexes. The new complexes have been

tested for the catalytic activity in the reaction of

oxidation of alcohols in the presence of N-me-

thylmorpholine-N-oxide as co-oxidant. The new

complexes were also exhibited antimicrobial

investigations.

Keyw ords: Ruthenium(II) Complexes; Tetradentate

N2O2 Schiff Base; Characterization; Catalytic

Oxidation; Antimicrobial Activity

1. INTRODUCTION

Transition metal complexes with tetradentate Schiff

base ligands have been studied as catalyst for a number

of organic oxidation and reduction reactions and electro

chemical reduction processes [1,2]. The accessibility of

ruthenium higher oxidation states [3,4] converts them

into excellent catalyst for redox reactions. Particularly,

metal complexes of ruthenium have demonstrated to be

useful laboratory and industrial homogeneous catalysts

in the epoxidation of alkenes and oxidation of alcohols

using iodosylbenzene, sodium hypochlorite hydrogen

peroxide and N-methylmorpholine-N-oxide as oxygen

sources [5-8]. Further the oxidation of organic substrates

mediated by high valent ruthenium-oxo species evokes

much interest in modeling of cytochrome p.450 [9].

Sharpless et al. [10] carried out a yield oriented study of

oxidation of cholesterol, geranial etc. catalyzed by ru-

thenium complexes in the presence of N-methylmor-

pholine-N-oxide and N, N-dimeth ylaniline-N-oxide. Fur-

thermore, the catalytic activities of ruthenium complexes

containing tertiaryphosphine or arsine ligands are well

established [11,12]. Tetradentate Schiff base complexes

have been employed as catalysts for many reactions and

as biological models in understanding the structure of

bio molecules and biological process [13,14].

In addition, the chemistry of chelating tetradentate

Schiff base ligands with ruthenium has also been exten-

sively studied [15]. This is due to the fact that Schiff

bases offer opportunities for inducing substrate chirality,

tuning metal centered electronic factors, enhancing solu-

bility and stability and their use as either homogeneous

or heterogeneous catalysis [16-18]. The oxidation of

primary and secondary alcohols into their corresponding

aldehydes and ketones respectively, plays a central role

in organic synthesis [19,20]. In continuation of our re-

search interest [21] to understand the role of these sim-

ple and inexpensive N2O2 donor Schiff base ligands to-

wards ruthenium, the reaction of Schiff bases derived

from isatin and diamines with ruthenium(II) precursors

containing PPh3/AsPh3/py/pip has been carried out. Thus,

the present work describes the results of synthesis, char-

acterization and properties of hexa coordinated Ru(II)

complexes exhibiting a N2O2 ligating core with their

catalytic activity towards oxidation of alcohols in the

presence of NMO. Further, the antibacterial activity of

the Schiff bases and their ruthenium complexes were

examined. The following Schiff bases, derived from the

condensation of isatin with ethylenediamine/o-phenyle-

nediamine/propylene diamine (Scheme 1), were used to

prepare the new ruthenium (II) complexes.

V. V. Raju et al. / Natural Science 3 (2011) 542-550

543

Scheme 1. Keto-enol tautomerism.

2. EXPERIMENTAL

2.1. Materials

The Schiff bases were prepared by the reported pro-

cedure [21,22]. All the reagents used were analytical

reagent grade. Solvents were purified and dried accord-

ing to standard procedures. RuCl3.3H2O, triphenylpho-

sphine, propylenediamine, ethylenediamine, o-phenyle-

nediamine and isatin were purchased from Loba Chemie

Pvt Ltd., Bombay, India and were used as such without

further purification. [RuHCl(CO)(PPh3)3] [23], [RuHCl

(CO)(B)(PPh3)2] [24] (where B = py/pip) and [RuHCl

(CO)(AsPh 3)3] [25] were prepared by reported literature

methods.

2.2. Physical Measurements

The analysis of C, H and N were performed on a

Carlo Erba 1160 model 240 Perkin Elmer CHN analyzer,

IR spectra were recorded in KBr pellets in the 4000 -

400 cm–1 region in a Jasco 400 plus spectrophotometer.

Electronic spectra were recorded in CH2Cl2 solution

with a Hitachi U – 3210 spectrophotometer in the range

of 800 - 200 nm. 1H-NMR and 31P-NMR spectra were

recorded on a Burker 400 MHz instrument using TMS as

an internal reference. Melting points were recorded with

Raaga apparatus and were uncorrected.

2.3. Synthesis of New Carbonyl Complexes

of RU(II)

To a solution of [RuHCl(CO)(EPh3)2(B)] [where E = P

or As; B = PPh3/py/pip/AsPh3] (0.1 g, 0.1 - 0.13 mmol)

in benzene (25 cm3),was added the appropriate Schiff

base (0.039 - 0.053 g, 0.1- 0.13 mmol). The solution was

heated under reflex for 6 hrs. Then, it was concentrated

to ca.3 cm3, cooled and new complexes were separated

upon addition of small quantity (6 cm3) of light petro-

leum (60 - 80˚C). The products were filtered, washed

with light petroleum, recrystalysed from CH2Cl2/light

petroleum mixture and dried in vacuo (yield: 65% -

70%). The purity of the complexes was checked by TLC.

2.4. Catalytic Oxidation

Catalytic oxidation of alcohols to the corresponding

carbonyl compounds by ruthenium(II) carbonyl Schiff

base complexes was studied in the presence of NMO as

co-oxidant by a typical reaction using the complex

[Ru(CO)(B)L] as catalyst, and the alcohol as substrate at

a 1:100 molar ratio. For this purpose, a solution of ru-

thenium complex (0.01 mmol) in 20 cm3 CH2Cl2 was

added to the solution of the substrate (1mmol) and NMO

(3 mmol) and the mixture was stirred for 3 - 7 hrs at

room temperature. The solvent was evaporated from the

mother liquor under reduced pressure and the residue

was then extracted with petroleum ether (60˚C - 80˚C).

2.5. Antibacterial Activity Studies

Pathogenic microbials namely Escherichia Coli, Aero-

monas hydrophila and Salmonella typhi were used to test

the biological potential of the isatin diimine and their

carbonyl complexes of ruthenium (II). The antibacterial

activities of the complexes were determined by disc dif-

fusion method [26]. The bacteria were cultured in nutri-

ent agar medium in petriplates and used inoculums for

the study. The complexes to be tested were dissolved in

DMSO to a final concentration of 0.25%, 0.5% and 1%

and soaked in filter paper disc of 5 mm diameter and of

1 mm thickness. The disc were placed on the previously

seeded plates and incubated at 35 ± 2˚C for 24 hrs. The

diameter of inhibitory zone around each disc was meas-

ured after 24 hrs. Streptomycin was used as a standard.

3. RESULTS AND DISCUSSIONS

3.1. Analytical Studies

Complexes of general formula [Ru(CO)(B)(L)] (where

B = PPh3/AsPh3/py/pip; L= dibasic tetradentate Schiff

bases) were synthesized by the reactions of

[RuHCl(CO)(PPh3)3], [RuHCl(CO)(AsPh3)3] and

[RuHCl(CO)(PPh3)2(B)] (where B = py/pip) with the

respective tetradentate Schiff bases (Scheme 2) in a 1:1

molar ratio in benzene.

The analytical data for the new complexes agree well

with the proposed molecular formula as given in Table 1.

In all the reactions it has been observed that the Schiff

bases behave as a dibasic tetratentate ligands by substi-

tuting the chloride ion, hydride ion and two triphenyl-

phosphine/arsine groups from each mole of the starting

complexes to form the mono nuclear complexes. These

observations indicate a more labile nature for the Ru-P

bond compared to the Ru-N bond of the heterocyclic

nitrogen bases in these complexes. The difference in the

strength of Ru-P/As and Ru-N bonds may be explained

as due to the better σ donation ability of the nitrogen

bases compared to that of triphenylphosphine/ arsine.

The Schiff base ruthenium(II) complexes are highly col-

ored, stable to air and light and soluble in chloroform,

methylene chloride, benzene and DMSO.

3.2. I.R. Spectra

The most important IR bands are presented and as-

V. V. Raju et al. / Natural Science 3 (2011) 542-550

544

signed in Table 2. The bands appearing at 1740 - 1715

cm–1 and 1652 - 1619 cm–1 in the ligand spectra were

assigned to stretching vibration modes of C = O and C =

N respectively. All the bands assigned to stretching vi-

bration modes in the free ligands changed in the spectra

of metal complexes. New bands recorded at 1599 -1583

cm–1 and 1637 - 1600 cm–1 vibration modes respectively

suggest the enolisation of the NH group of isatin and

coordination through the oxygen of the C-O group [21,

27]. The formation of the Ru-O and Ru-N bands is fur-

ther supported by the appearance of νM-O and νM-N band

in the regions 576 - 541 cm–1 and 492 - 475 cm–1 respec-

Scheme 2. Preparation of new Ru(II) Schiff base complexes.

Table 1. Analytical data of new Ru(II) complexes.

Calculated(found)%

Complex Mp (˚C) Yield (%)

C H N

[Ru(CO)(PPh3)(L1)] 168 80 62.80(62.61) 3.81(3.76) 7.92(8.05)

[Ru(CO)(AsPh3)(L1)] 158 78 59.12(59.25) 3.59(3.67) 7.46(7.52)

[Ru(CO)(py)(L 1)] 143 75 54.95(55.37) 3.24(3.10) 13.35(12.50)

[Ru(CO)(pip)(L1)] 125 78 54.33(53.57) 4.34(4.01) 13.40(12.67)

[Ru(CO)(PPh3)(L2)] 172 75 63.24(64.61) 4.02(3.85) 7.77(7.21)

[Ru(CO)(AsPh3)(L2)] 160 80 59.61(62.01) 3.79(3.51) 7.32(6.56)

[Ru(CO)(py)(L 2)] 145 70 55.76(57.75) 3.53(3.87) 13.01(12.58)

[Ru(CO)(pip)(L2)] 130 78 55.15(55.75) 4.64(4.38) 12.86(11.96)

[Ru(CO)(PPh3)(L3)] 157 80 65.16(66.18) 3.58(3.85) 7.41(7.58)

[Ru(CO)(AsPh3)(L3)] 142 76 61.57(62.75) 3.38(3.15) 7.00(6.91)

[Ru(CO)(py)(L 3)] 137 75 58.74(59.62) 2.97(3.03) 12.24(11.56)

[Ru(CO)(pip)(L3)] 125 75 58.13(57.67) 3.98(3.87) 12.11(11.91)

Table 2. IR and UV - Visible Spectral data for the ligands and new Ru(II) complexes.

Complex ν(C = N) ν(C = O) ν(C - O) ν(M - N) ν(M - O) λmax

HL1 1619 1720 -

[Ru(CO)(PPh3)(L1)] 1620 - 1585 475 541 246, 320, 360, 600

[Ru(CO)(AsPh3)(L1)] 1628 - 1583 480 547 250, 320, 362,590

[Ru(CO)(py)(L 1)] 1600 - 1590 482 562 248, 316, 368, 593

[Ru(CO)(pip)(L1)] 1637 - 1583 488 576 246, 315, 368, 598

HL2 1652 1715 -

[Ru(CO)(PPh3)(L2)] 1636 - 1589 487 560 246, 315, 568

[Ru(CO)(AsPh3)(L2)] 1622 - 1597 490 570 248, 368, 408

[Ru(CO)(py)(L 2)] 1628 - 1599 492 575 248, 316, 463, 590

[Ru(CO)(pip)(L2)] 1630 - 1585 479 547 250, 350, 403

HL3 1630 1740 -

[Ru(CO)(PPh3)(L3)] 1607 - 1587 476 550 248, 318, 550

[Ru(CO)(AsPh3)(L3)] 1615 - 1592 490 570 248, 325, 563

[Ru(CO)(py)(L 3)] 1603 - 1590 486 568 246, 313, 569, 600

[Ru(CO)(pip)(L3)] 1600 - 1588 482 571 246, 320, 350, 596

V. V. Raju et al. / Natural Science 3 (2011) 542-550

545

tively in the spectra of the chelates [21,28,29]. The most

important conclusion drawn from the infrared spectral

evidence is that the diamine bis(isatin) Schiff base ligand

is acting as chelating agent towards the central metal ion

as dibasic ONNO tetradentate ligand, via the two coor-

dinating sites of nitrogen atoms and two negatively

charged oxygen atoms of isatin residues forming five-

membered chelating rings [30]. In addition, other char-

acteristic bands due to PPh3 and AsPh3 are also present

around 1438 cm–1 [31], in the spectra of Schiff base

complexes. A medium intensity band is observed in the

1020 cm–1 region, characteristics of the coordinated

pyridine or piperidine [21,32]. In all the ruthenium com-

plexes the band due to terminally coordinated C ≡ O

group appeared at 1900 - 1944 cm–1 [33].

3.3. Electronic Spectra

The electronic spectra of all the complexes in dichlo-

romethane showed three to four bands in the region 246

- 600 nm. All the Schiff base ruthenium complexes are

diamagnetic, indicating the presence of ruthenium in the

+2 oxidation state. The ground state of ruthenium(II) in

an octahedral environment is 1A1g from the t6

2g configu-

ration and excited states corresponding to the t5

2g e1

configurations are 3T1g, 3T2g, 1T1g and 1T2g. Hence four

bands corresponding to the transition 1A1g → 3T1g, 1A1g

→

3T2g, 1A1g→ 3T1g and 1A1g → 1T2g are possible in the

order of increasing energy. The bands around 600 - 550

nm and 463 - 403 nm are assigned to 1A1g → 1T1g [34,35]

and the charge transfer reactions respectively are listed

in Table 2. The charge transfer bands observed in all the

complexes due to M → L transitions are possible in the

visible region [36-38]. Moreover the presence of car-

bonyl, triphenylphosphine/arsine and heterocyclic bases

as ligands, which are capable of producing strong ligand

field in eg

* which is relatively higher energy levels. This

band has been assigned to the charge-transfer transition

arising from the excitation of an electron from the metal

t2g level to the unfilled molecular orbital’s derived from

the eg

* level of the ligands should appear in the relatively

high energy region compared to those due to t2g → e

transitions [34-36]. The other high energy bands have

been designated as π-π* and n-π* transitions for the elec-

trons localized on the azomethine group of Schiff bases

[32]. The pattern of the electronic spectra of all the com-

plexes indicated the presence of an octahedral environ-

ment around the ruthenium(II) ion, similar to that of

other octahedral ruthenium(II) complexes [37].

3.4. 1H-NMR Spectra

The 1H NMR spectra of some complexes were re-

corded to confirm the bonding of the Schiff base to the

ruthenium ion and given in the Table 3. Multiplets are

observed around 7.2 - 7.8 ppm in all the complexes and

have been assigned to the aromatic protons of triphenyl-

phophine, triphenylarsine, pyridine, piperidine and isatin

Schiff base ligands [29]. A singlet appears in the region

1.36 - 1.4 ppm for the methylene protons [39]. In the

complexes [Ru(CO)(PPh3)(L3)] and [Ru(CO)(AsPh3)(L3)]

an extra singlet was found in the region at 2.05 ppm,

which has been assigned to the extra methylene group

present in the Schiff base. The 1H NMR spectra of the

neutral diamagnetic chelates of the type [Ru(CO)(B)(L)]

are similar to those of the ligands, excepting that the

signal due to NH proton of isatin disappears. This proves

the deprotonation of NH group upon complexation and

supports the above NMR spectral data suggesting that

the ligand acts as dibasic tetra dentate chelating agent.

3.5. 31P-NMR Spectra

The 31P-NMR spectra for a few of the complexes have

been recorded in order to confirm the presence of

triphenylphosphine group and to determine the geometry

of the complexes (Table 3). The appearance of singlet

at 28.78, 28.75 and 28.70 ppm for the complexes

[Ru(CO)(PPh3)(L1)], [Ru(CO)(PPh3)(L2)] and

[Ru(CO)(PPh3)(L3)] respectively indicates the presence

of one triphenylphosphine group in these complexes.

3.6. Catalytic Activity of the Complexes

Catalytic oxidation of primary alcohols and secondary

alcohols by the synthesized ruthenium(II) carbonyl

Schiff base complex [Ru(CO)(B)(L)]was carried out in

CH2Cl2 in the presence of NMO. Results of the present

investigation suggest that the complex is able to react

efficiently with NMO to yield a high valent ruthenium-

oxo species [15,40] capable of transferring oxygen atom

to alcohols. The oxidation of benzylalcohol to benzal-

dehyde resulted in 89% yield. Further, the complex ef-

fectively catalyzes the oxidation of aliphatic alcohols

such as butane-2-ol, to the corresponding ketones effec-

tively and is evident from Table 4. Moreover, the com-

plex effectively catalyzes the oxidation of five and six

membered cyclic alcohols to the corresponding ketones

with the conversion rates to the extent of 90% and 82%

respectively. The reaction provides a new environment

friendly route to the conversion of alcoholic functions to

carbonyl group and water is the only byproduct during

the course of the reaction. It has been concluded that the

complexes have a better catalytic efficiency in the case

of oxidation of primary and secondary alcohols in the

presence of NMO.

3.7. Antibacterial Studies

The in vitro antibacterial screening of the ligands and

V. V. Raju et al. / Natural Science 3 (2011) 542-550

546

Table 3. NMR Spectral data of new Ru(II) complexes.

S. No. Complex 1H-NMR data (ppm) 31P-NMR data (ppm)

1. [Ru(CO)(PPh3)(L1)] 7.2 - 7.6 (Ph, m),1.36 (N-(CH2)2, s) 28.78

2. [Ru(CO)(AsPh3)(L1)] 7.3 - 7.6 (Ph, m),1.36 (N-(CH2)2, s) -

3. [Ru(CO)(py)(L1)] 7.2 - 7.6 (Ph, m),1.4 (N-(CH2)2, s) -

4. [Ru(CO)(PPh3)(L2)] 7.3 - 7.8 (Ph, m) 28.75

5. [Ru(CO)(AsPh3)(L2)] 7.2 - 7.7 (Ph, m) -

6. [Ru(CO)(pip)(L2)] 7.2 - 7.6 (Ph, m) -

7. [Ru(CO)(PPh3)(L3)] 7.3 - 7.6 (Ph, m),1.36 (N-(CH2)2, s), 2.05 (CH2,s)28.70

8. [Ru(CO)(AsPh3)(L3)] 7.2 - 7.6 (Ph, m),1.36 (N-(CH2)2, s), 2.05 (CH2,s)-

Table 4. Catalytic oxidation of alcohols by Ru(II) complexes.

Complex Substrate Product Yielda Turnoverb

Benzylalcohol Benzaldehyde 76 75

[Ru(CO)(PPh3)(L1)]

Cyclohexanol Cyclohexanone 82 80

Butane-2-ol Butanone 84 88

Cyclopentanol Cyclopentanone 90 92

Benzylalcohol Benzaldehyde 80 81

[Ru(CO)(AsPh3)(L1)]

Cyclohexanol Cyclohexanone 82 80

Butane-2-ol Butanone 73 78

Cyclopentanol Cyclopentanone 89 88

Benzylalcohol Benzaldehyde 76 78

[Ru(CO)(py)(L 1)]

Cyclohexanol Cyclohexanone 83 86

Butane-2-ol Butanone 74 79

Cyclopentanol Cyclopentanone 90 92

Benzylalcohol Benzaldehyde 77 79

[Ru(CO)(pip)(L1)]

Cyclohexanol Cyclohexanone 85 87

Butane-2-ol Butanone 80 84

Cyclopentanol Cyclopentanone 91 95

Benzylalcohol Benzaldehyde 81 85

[Ru(CO)(PPh3)(L2)]

Cyclohexanol Cyclohexanone 80 83

Butane-2-ol Butanone 78 87

Cyclopentanol Cyclopentanone 90 91

Benzylalcohol Benzaldehyde 82 81

[Ru(CO)(AsPh3)(L2)]

Cyclohexanol Cyclohexanone 81 85

Butane-2-ol Butanone 72 76

Cyclopentanol Cyclopentanone 89 86

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Benzylalcohol Benzaldehyde 82 84

[Ru(CO)(py)(L 2)]

Cyclohexanol Cyclohexanone 80 84

Butane-2-ol Butanone 71 74

Cyclopentanol Cyclopentanone 90 87

Benzylalcohol Benzaldehyde 76 79

[Ru(CO)(pip)(L2)]

Cyclohexanol Cyclohexanone 83 78

Butane-2-ol Butanone 72 75

Cyclopentanol Cyclopentanone 90 93

Benzylalcohol Benzaldehyde 75 78

[Ru(CO)(PPh3)(L3)]

Cyclohexanol Cyclohexanone 86 82

Butane-2-ol Butanone 76 80

Cyclopentanol Cyclopentanone 93 90

[Ru(CO)(AsPh3)(L3)] Benzylalcohol Benzaldehyde 73 77

Cyclohexanol Cyclohexanone 79 80

Butane-2-ol Butanone 70 73

Cyclopentanol Cyclopentanone 91 86

[Ru(CO)(py)(L 3)] Benzylalcohol Benzaldehyde 75 78

Cyclohexanol Cyclohexanone 75 79

Butane-2-ol Butanone 72 75

Cyclopentanol Cyclopentanone 93 80

[Ru(CO)(pip)(L3)] Benzylalcohol Benzaldehyde 67 70

Cyclohexanol Cyclohexanone 81 80

Butane-2-ol Butanone 78 81

Cyclopentanol Cyclopentanone 91 86

their ruthenium complexes have been carried out against

Escherichia Coli, Aeromonas hydrophila and Salmonella

typhi using a nutrient agar medium by disc diffusion

method. The results (Table 5) showed the complexes

exhibit moderate activity against Escherichia Coli, Aero-

monas hydrophila and Salmonella typhi. The toxicity of

ruthenium chelates increases on increasing the concen-

tration [41]. The increase in the antibacterial activity of

metal chelates may be due to the effect of the metal ion

on the normal cell process. A possible mode of the toxic-

ity increase may be considered in light of Tweeds chela-

tion theory [42]. Chelation considerably reduces the po-

larity of the metal ion because of partial sharing of its

positive charge with the donor groups and possible π-

electron delocalization over the whole chelate ring. Such

chelation could enhance the lipophilic character of the

central metal atom, which subsequently favors its per-

meation through the lipid layers of cell membrane. Fur-

thermore, the mode of action of the compounds may

involve in the formation of a hydrogen bond through the

azomethine (>C = N) group with the active centers of

cell constituents, resulting in interference with the nor-

mal cell processes [42]. Though the complexes possess

activity, it could not reach the effectiveness of the stan-

dard drug streptomycin. The variation in the effective-

ness of the different compounds against different organ-

isms depend either on the impermeability of the cells of

the microbes or differences in ribosomes of microbial

cells [40,41].

Based on the analytical, spectral (IR, electronic, 1H

NMR and 31P-NMR) data, Scheme 3 octahedral stru-

cture has been tentatively proposed for all the new car-

bonyl Schiff base complexes of ruthenium (II).

V. V. Raju et al. / Natural Science 3 (2011) 542-550

548

Table 5. Antibacterial activity of ligands and Ru(II) complexes (diameter of inhibition zones-mm).

Escherichia coli Aeromonas hydrophila Salmonella typhi

Ligand/Complex

0.25% 0.5% 1.0%0.25% 0.5%1.0% 0.25% 0.5%1.0%

L1 10 11 13 11 12 13 9 12 13

[Ru(CO)(PPh3)(L1)] 12 14 16 14 17 18 13 16 20

[Ru(CO)(AsPh3)(L1)] 11 15 17 12 16 20 14 17 21

[Ru(CO)(py)(L 1)] 14 16 20 13 17 19 15 17 20

[Ru(CO)(pip)(L1)] 16 18 20 13 17 19 15 18 20

L2 10 12 14 9 12 15 10 11 14

[Ru(CO)(PPh3)(L2)] 12 15 19 11 16 18 12 18 20

[Ru(CO)(AsPh3)(L2)] 15 18 21 12 18 21 14 15 18

[Ru(CO)(py)(L 2)] 14 16 19 14 19 20 18 20 21

[Ru(CO)(pip)(L2)] 15 20 21 16 18 21 19 20 21

L3 10 11 13 12 14 15 10 11 14

[Ru(CO)(PPh3)(L3)] 12 14 17 14 16 18 15 18 20

[Ru(CO)(AsPh3)(L3)] 14 18 20 15 18 20 17 18 21

[Ru(CO)(py)(L 3)] 16 17 21 14 17 19 19 22 23

[Ru(CO)(pip)(L3)] 17 18 22 16 18 22 17 19 22

Streptomycin 22 23 28 21 37 29 29 21 25

Scheme 3. Structure of New Ru(II) complexes.

4. CONCLUSIONS

A new family of carbonyl complexes of ruthenium(II)

containing N2O2 donor Schiff bases incorporating tri-

phenylphosphine/triphenylarsine/pyridine/piperidine li-

gands were synthesized and characterized. The new com-

plexes were tested as a new and efficient catalyst for the

oxidation of primary and secondary alcohols to their

corresponding aldehydes and ketones with excellent yields

in the presence of N-methylmorpholine-N-oxide. Further

the possible explanations for the mode of action of these

complexes against three different microbes are described.

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