Spectral and biological activity properties of some new aminocyclodiphosph(V)azane derivatives and their complexes

Article abstract of DOI:10.1080/10426500801963566

The ligand aminocyclodiphosph(V)azane derivative (III) and its complexes with Co(II), Ni(II), Cu(II) and Pd(II) ions were prepared and characterized by microanalytical, FTIR, 1H and 31P NMR, UV/Visible, analysis and magnetic moments. The ligand acts in a tetrahedral manner forming 2:1 metal to ligand ratio. Electronic spectra and magnetic susceptibility measurements reveal octahedral geometry for Co(II), Ni(II) and Cu(II) complexes and square planar geometry for Pd(II) complex. The powder XRD studies confirm the amorphous nature of the complexes. The free ligand (III) and its metal complexes have been tested in vitro against Alternarie alternate, Aspergillus flavus, Aspergillus nidulans and Aspergillus niger fungi and Streptococcus, Staph, Staphylococcus and Escherchia coli bacteria in order to assess their antimicrobial potential. The results indicate that the ligand and its metal complexes possess antimicrobial properties. Copyright Taylor & Francis Group, LLC.

Full text of DOI:10.1080/10426500801963566

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Spectral and Biological Activity
Properties of Some New
Aminocyclodiphosph(V)azane
Derivatives and Their
Complexes
A. M. A. Alaghaz a
a Chemistry Department, Faculty of Science , Al-
Azhar University (for Boys), Nasr City , Cairo, Egypt
Published online: 12 Aug 2008.
To cite this article: A. M. A. Alaghaz (2008) Spectral and Biological Activity Properties
of Some New Aminocyclodiphosph(V)azane Derivatives and Their Complexes,
Phosphorus, Sulfur, and Silicon and the Related Elements, 183:9, 2287-2300, DOI:
10.1080/10426500801963566
To link to this article: http://dx.doi.org/10.1080/10426500801963566
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Phosphorus, Sulfur, and Silicon, 183:2287–2300, 2008
Copyright © Taylor & Francis Group, LLC
ISSN: 1042-6507 print / 1563-5325 online
DOI: 10.1080/10426500801963566
Spectral and Biological Activity Properties of Some
New Aminocyclodiphosph(V)azane Derivatives
and Their Complexes
A. M. A. Alaghaz
Chemistry Department, Faculty of Science, Al-Azhar University
(for Boys), Nasr City, Cairo, Egypt
The ligand aminocyclodiphosph(V)azane derivative (III) and its complexes with
Co(II), Ni(II), Cu(II) and Pd(II) ions were prepared and characterized by microan-
alytical, FTIR, 1H and 31P NMR, UV/Visible, analysis and magnetic moments. The
ligand acts in a tetrahedral manner forming 2:1 metal to ligand ratio. Electronic
spectra and magnetic susceptibility measurements reveal octahedral geometry for
Co(II), Ni(II) and Cu(II) complexes and square planar geometry for Pd(II) complex.
The powder XRD studies confirm the amorphous nature of the complexes. The free
ligand (III) and its metal complexes have been tested in vitro against Alternarie al-
ternate, Aspergillus flavus, Aspergillus nidulans and Aspergillus niger fungi and
Streptococcus, Staph, Staphylococcus and Escherchia coli bacteria in order to as-
sess their antimicrobial potential. The results indicate that the ligand and its metal
complexes possess antimicrobial properties.
Keywords 31P NMR; aminocyclodiphosph(V)azane; metal complexes
INTRODUCTION
The reaction of hexachlorocyclodiphosph(V)azanes with aromatic
and aliphatic amines, active methylene containing compounds, and
bifunctional reagents have been investigated in some detail.1–3 Little
is known about the interaction of hexachlorocyclodiphosph(V)azane
with aminothiophene derivatives and their metal complexes. In
the present work, the interaction of 1,3-di-phenyl-2,2,2,4,4,4-
hexachlorocyclodiphos-(V)azane(I)
with
2-amino-3-cyano-4,5-
dimethylthiophene (II) and its metal complexes have been reported.
Received 18 September 2007; accepted 14 December 2007.
Address correspondence to A. M. A. Alaghaz, Chemistry Department, Faculty of
Science, Al-Azhar University (for Boys), Nasr City, Cairo, Egypt. E-mail: aalajhaz@
hotmail. com
2287

2288
A. M. A. Alaghaz
RESULTS AND DISCUSSION
The yields of the complexes are lower than those of the ligand. The
low yields may be due to the steric hindrance around the coordination
centre. The ligand and their complexes are soluble in common organic
solvents such as DMF, DMSO, and THF. The results of the elemental
analyses, given in Table I, are in accord with the composition suggested
for the ligand and their metal complexes. The formula of the free ligand
was investigated using elemental analyses, IR, UV, 1H, and 31P NMR.
IR Spectra
The assignment of the important bands of the free ligand is given
in Table II. The spectra reveal the characteristic bands of the νP-NH
stretching vibrations of the ligand at 2606 cm−1, which is similar to
those assigned by Abd-Ellah2 and Pustinger.4 The band appeared at
3389 cm−1 is attributed to the νNH stretching vibration. The band
observed at 2219 cm−1 is ascribed to the νC≡N stretching vibration,
which appeared at 2198 cm−1 in compound (II).5 The shift of this
band to higher frequency in the ligand is considered as an evidence
for the ligand formation. The νP-Cl stretching vibration is observed at
490 cm−1 6,7 The band at 1243 cm−1 was assigned to the νP N stretch-
.
ing vibration.8,9 Bands appear in the range 1625–1395 cm−1 may be
attributed to νC=C of the aromatic rings and attached compounds (II).10
Moreover, the IR spectra showed weak band at 635 cm−1 due to the νC-S
stretching vibration of thiophene ring. The weak band observed at 3175
cm−1 is due to aromatic C H stretching vibrations.11
Electronic Spectra
The electronic spectrum of the ligand (III) showed an absorption band
at longer wavelength 282 nm than that associated with its dimer (I)
at 277 nm.12 This bathochromic shift could be expected due to the re-
placement of one chlorine atom of each phosphorus atom of the phos-
phazo ring of dimer (I) by chromophoric group containing conjugated
system such as 2-amino-3-cyano-4,5-dimethylthiophene (II) Scheme 1.
It is worthwhile that the expected band at 275 nm,25 characteristic for
the delocalization of the nonbonding electrons on the nitrogen atoms
along the phosphazo ring of the dimeric structure was observed in the
spectrum of ligand (III) at 282 nm, indicated the presence of the phosp-
hazo ring. Moreover, the new band observed at 355 nm corresponding to
n-π* the transition of attached compound (II), was absent in its dimer
(I), that is considered as an evidence for the ligand formation.

2289

2290

Diphosph(V)azane Derivatives and Their Complexes
2291
SCHEME 1 Formula of ligand III: 1,3-diphenyl-2,2,4,4-tetrachloro-2,4- bis (2-
amino-3-cyano-4,5-dimethylthiophene) cyclodiphosph(V)azane.
1H and 31P NMR Spectra of Ligand(III)
1
The H NMR spectrum of the ligand (III) showed characteristic pro-
ton signals at δ = 7.93 ppm corresponding to phenyl protons and the
signal at δ = 10.49 ppm due to N-H proton, which was disappeared on
the addition of D2O because of the proton exchange. Two sharp singlet

2292
A. M. A. Alaghaz
SCHEME 2 The formula of the four complexes.
signal bands at δ = 2.50 and 2.80 ppm were assigned to the protons of
the methyl groups in two different environments. The 31P NMR of the
ligand records a signal at δ = 25.92 ppm, which supports the phosphazo
ring structure.
Metal Complexes
All the complexes are polycrystalline solids and the elemental analy-
sis results (Table I) agree well with the binuclear structure shown in
Scheme 2. The purities of all these compounds were checked by TLC

Diphosph(V)azane Derivatives and Their Complexes
2293
by dissolving the appropriate complex in DMF and using ethyl acetate
(80%) – methanol (15%) – acetic acid (5%) as eluant. Only one spot was
observed in each case after developing in an iodine chamber, indicating
that the compounds were pure.
Conductimetric Titrations
The calculated molar ratio [L]/[M] are plotted against the corrected
molar conductance values. The results indicate that the conductance
increases with the addition of the metal ion solutions due to the release
of the highly conducting hydrogen ions because of chelation. Inspection
of the titration curves shows the presence of two distinctive breaks at
metal to ligand molar ratios of 2M:1L.2,3
Magnetic and Electronic Spectral Studies
On complexation the lower-energy band observed at 345 nm in the
spectrum of the free ligand III, which was assigned to, is shifted to a
red shift, while the other one at 282 nm of the π-π* transition is slightly
shifted to a blue shift.
The magnetic susceptibility measurement at room temperature of
the green Co(II) complex IVa, gave magnetic moment value µeff of
5.04 B.M., this high value may be due to orbital contribution correspond-
ing to three unpaired electrons are expected for a week field ligand. The
electronic spectra of the Co(II) complex as nujol mulls and/or solution
in ethanol table 3 showed. Two Peaks at 705 nm and 554 nm, which
4
4
may be assigned to 4T1g(F) → A1g(F) and 4T1g(F) → T1g(P) and is con-
sistent with the octahedral geometry.1,3 The peaks observed at 255 nm,
310 nm and 380–405 nm regions, were assigned to π → π* and n→ π*
transitions, respectively. Finally, the low value of molar conductance
(5.0 ꢁ−1 mol−1 cm2) suggests a non-electrolytic nature of this complex
in DMSO. The high melting point of the Co(II) complex (>300◦C) sug-
gest the existence of a strong covalent bonding between the Co(II) ion
and the ligand under investigation.
The deep brown Ni-complex IVb gives value µeff 2.92 B.M. that is
indicative of two unpaired electrons. The electronic spectrum of the Ni
(II) complex IVb shows absorption band at 712 nm which may be in-
4
4
vestigated to the A2g(F) → T1g(F), week bands observed on the high
and low energy sides of the 712 nm band have been assigned to spin
forbidden bands.1,3 The value of molar conductance in DMSO (6.0 ꢁ−1
mol−1 cm2) indicating a non-electrolytic nature around the Ni(II) ion.
The high melting point of the Ni(II) complex (>300◦C) suggest the exis-
tence of a strong covalent bonding between the Ni(II) ion and the ligand
under investigation.

2294
A. M. A. Alaghaz
The Cu(II) complex IVc gave a band at 576 nm, suggesting the exis-
tence of a transition from dxy, d2 and dxz, dyz transfer to the antibond-
ing and half-filled dx2−dy2 level zwhich is consistent with an octahedral
configuration.13 The observed magnetic moment of the Cu(II) complex
is 2.04 B.M., which confirms the octahedral structure of this complex.
In addition, the value of molar conductance in DMSO (7.0 ꢁ−1 mol−1
cm2) suggests a non-electrolytic nature of this complex. The high melt-
ing point of the Cu(II) complex (>300◦C) suggest the existence of a
strong covalent bonding between the Cu(II) ion and the ligand under
investigation.
Palladium complex (IVd) has three spin allowed singlet–singlet d–d
1
1
transitions, which are 1A1g→ A2g (716 nm), 1A1g→ B1g (498 nm) and
1A1g→ Eg (415 nm).14,15 These transitions are from the lower lying d or-
1
bital to the empty dx2−y2 orbital. The strong band at 375 nm is assignable
to a combination of M→L (charge transfer) and d–d bands. The molar
conductance value of Pd(II) complex (6.0 ꢁ−1 mol−1 cm2) indicating that
this complex is non-electrolytic in nature. The high melting point of
the Pd(II) complex (>300◦C) suggest the existence of a strong covalent
bonding between the Pd(II) ion and the ligand under investigation.
It is concluded from the above results that the proposed formula of
the investigated complexes coordination with metal ions occurs through
the nitrogen of the NH and C N groups as shown in the Scheme 2.
IR Spectra
The most important vibrational bands of the ligand and its metal com-
plexes are given in Table II. The results of IR spectra of the metal
complexes show absorption bands of both νC≡N and νN-H at lower fre-
quencies than those of the free ligand III, indicating that the metal
ions are coordinated to the nitrogen atoms of both C N and NH groups
of the ligand III. Further, in all the metal complexes, there were new
medium to weak bands observed at lower frequencies in the range (252–
305 cm−1) were assigned to νM-N and two bands at 550–559 cm−1 were
attributed to νm-o for IVa-d. ,
1–3 The bands observed at 1563–1470 cm−1
1 and, 1619–1561 cm−1 in both Co (II), Ni(II) and Cu(II) complexes
were attributable to νsymOCO and νasymOCO respectively, which indi-
cated that the acetate groups coordinate as a monodentate to the central
metal cation of Co(II), Ni(II), and Cu(II) complexes, respectively. This
is supported with the observed characteristic νM-O band.1–3
The spectra of nitrato complex (IVd) gave additional bands around
1232, 1045, and 877 cm−1, which are consistent with the monodentate
nature of this group.10

Diphosph(V)azane Derivatives and Their Complexes
2295
FIGURE 1 X-ray powder diffraction of Cu(II) complex.
Moreover, the characteristic vibrational bands corresponding to the
νP-NH, νP-N, and νp-Cl which were associated with all the complexes un-
der investigation are given in Table II.
Powder X-ray Diffraction
X-ray patterns of the Cu(II) complex IVc recorded at 2θ = 0–90 range
was shown in Figure 1. All the complexes are powder solids (amor-
phous). The resulted complexes are slightly soluble in DMF and DMSO
and are decomposed in diluted solutions of all strong acids. Attempts
to prepare single crystals were unsuccessful.
Antimicrobial Activities
The free ligand and its respective metal chelates were screened against
A. alternate, A. flavus, A. nidulence, and A. niger fungi and Strepropro-
teus, Staph, Staphylococcus and E. coli bacteria to asses their potential
antimicrobial agents. The results are quite promising. It is clear from
the antifungal screening data (Figure 2a), that the metal complexes are
more fungitoxic than the chelating agent itself. The bacterial screen-
ing results (Figure 2b) reveal that the free ligand (III) showed the

2296
A. M. A. Alaghaz
maximum activity against Streproproteus bacteria. Its copper, cobalt,
and palladium complexes also showed the maximum activity against
Streproproteus bacteria whereas the nickel complex showed the maxi-
mum activity against Staphylococcus bacteria. In general, the activity
was the least against Staph bacteria. The antimicrobial data reveal that
the complexes are more bioactive than the free ligand. The enhanced ac-
tivity of the metal complexes may be ascribed to the increased lipophilic
FIGURE 2 (a) Antifungal screening and (b) antibacterial screening.
(Continued)

Diphosph(V)azane Derivatives and Their Complexes
2297
FIGURE 2 (Continued)
nature of these complexes arising due to chelation.16 It was also noted
that the toxicity of the metal chelates increases on increasing the metal
ion concentration. It is probably due to faster diffusion of the chelates as
a whole through the cell membrane or due to the chelation theory. The
bounded metal may block enzymatic activity of the cell or else it may cat-
alyze toxic reactions among cellular constituents. It can be concluded
from all the results given above that the ligand acts as tetradentate
chelating agent, coordinates with transition metal ions to give square
planar/tetrahedral environments, around the metal ion anchor.

2298
A. M. A. Alaghaz
EXPERIMENTAL
Starting Materials
The preparation and purification of hexachlorocyclodiphosph-(V)azanes
(I) has been reported.2,3 The preparation of 2-amino-3-cyano-4,5-
dimethylthiophene (II) was carried out according to the Gewald
method.5
Synthesis of Ligand (III)
The solid of 2-amino-3-cyano-4,5-dimethylthiophene (II) (3.04 g;
0.02 mol) was added in small portions to a well-stirred solution of
the hexachlorocyclodiphosph(V)azane (I) (4.57 g; 0.01 mol) in 100 ml
acetonitrile over 0.5 h period. After the complete addition, the reaction
mixture was heated under reflux for 2 h with continuous stirring. After
completion of the reaction (HCl gas ceased to evolve), the reaction
mixture was filtered while hot and the filtrate was left to cool at
room temperature. The obtained solid (bright yellow) was filtered
washed several times with acetonitrile, followed by ether and then
dried in vacuo to give the corresponding aminocyclodiphosph(V)azane
derivative (III) (Scheme 1).
Preparation of the Solid Metal Complexes
A solution of the salts (0.002 mol) in 50 ml acetonitrile was added
dropwise to a solution of aminocyclodiphosph(V)azane derivative (III)
(0.001 mol) in 50 ml acetonitrile at room temperature with continu-
ous stirring. After the complete addition of the metal salt solution, the
reaction mixture was heated under reflux for 3 h. Then, the reaction
mixture was evaporated to give solid compounds, which recrystallized
from acetonitrile to give the products IVa-c. The analytical data of both
ligand and its metal complexes are listed in Table I.
Measurements
Elemental analysis of C, H, and N and S were carried out using
the Perkin-Elmer 2400 apparatus and phosphorus was determined
grave-metrically as phosphoammonium molybdate using the R. Voy
method.17 Infrared spectra were recorded in the solid state on a Matt-
son 5000 FTIR spectrometer using KBr disc technique. The absorbance
of solutions was measured in the UV/VIS range (200–800 nm) using
Unicam spectrophotometer model UV 2–100 and 1 cm matched quartz
1
cells. The H NMR spectra were recorded on a Varian Spectrometer

Diphosph(V)azane Derivatives and Their Complexes
2299
at 90 (22.5) MHz, using TMS as an internal reference. 31P NMR spec-
tra were run, relative to external H3PO4 (85%), with a Varian FT-80
spectrometer at 365 MHz. Magnetic measurements were recorded by
the Gouy method at room temperature using a magnetic susceptibility
balance (Johnson Mathey), Alfa product. Model No. (MK). The conduc-
tometric measurements in solutions were carried out using conductivity
TDS model 72. The X-ray powder diffraction analyses were carried out
by using Rigku Model ROTAFLEX Ru-200. Radiation was provided by
copper target (Cu anode 2000 W) high intensity X-ray tube operated at
40 kV and 35 MA. Divergence slit and the receiving slit were 1 and 0.1,
respectively.
Biological Activity
Antibacterial Screening
In vitro anti-microbial (anti-bacterial) activities of the synthesized
ligand and its metal complexes were tested using paper disc diffusion
method.18 The nutrient agar medium (peptone, beef extract, NaCl and
agar-agar) and 5 mm diameter paper discs of Whatman No. 1 were
used. The test compound was dissolved in methanol in 0.05–0.40% con-
centrations. The filter paper discs were soaked in different solutions of
the compound, dried, and then placed in the Petri plates (9 mm diame-
ter) previously seeded with the test organisms Streptococcus, Staph,
Staphylococcus and Escherchia coli. The plates were incubated for
24–30 h at 27 1◦C and the inhibition zone (mm) was measured around
each disc. As the organism grows, it forms a turbid layer, except in the
region where the concentration of antibacterial agent is above the mini-
mum inhibitory concentration and a zone of inhibition is seen. The size
of the inhibition zone depends upon the culture medium, incubation
conditions, rate of diffusion, and the concentration of the antibacterial
agent.
Antifungal Screening
The antifungal activity of the complexes was checked by dry weight
method for the Alternarie alternate, Aspergillus flavus, Aspergillus
nidulans, and Aspergillus niger fungi. The complexes were directly
added to the growth medium in varying concentration (0.05–0.40%
(w/v)). The actively growing mycelia (of the test fungi) were placed
on the medium with the help of inoculum needle and incubated at
27
1◦C for 7 days. The medium with the test solutions served as
“treated” while without them as “control” or “check.” The resulting
mycelia mats in each set were carefully removed, washed, dried, and

2300
A. M. A. Alaghaz
then weighed separately. The fungal growth was calculated from the
following relation:
fungal growth inhibition (%) = Cg − T /Cg × 100
(1)
g
where Cg is the average growth in the “control” or “check” set and T is
g
the average growth in the treated set.
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