spectral and thermal studies of 1,10-phenanthroline n,n
TRANSCRIPT
CROATICA CHEMICA ACTA
CCA-1703
CCACAA 59 (4) 945-949 (1986)
YU ISSN 0011-1643UDC 546.881
Note
Spectral and Thermal Studies of 1,10-PhenanthrolineN,N' -Dioxide Chelates of Oxovanadium(IV)
R. K. Agarwal* and Gyanendra Singh
Department of Chemistry, Lajpat Rai Post-Graduate CoLLege, Sahibabad-201005,Ghaziabad (U. P.), India
Received May 17, 1985
A new series of penta-coordinated oxovanadium{IV) chelatesof 1,10-phenanthroline N,N'-dioxide (Phen02) have been synthe-sized and characterized by conductance, magnetic moments, in-frared, electronic spectra and TG-data.
INTRODUCTION
The coordination chemistry of aromatic amine N-oxides has been reviewedin recent years'. Of the heterocyclic N-oxides studied by far the largestamount of work has been carried out with pyridine N-oxide and 2,2'bipyridylN,N'-dioxide1• But the study of coordinating ability of a similar ligand, i. e.1,10-phenanthroline N,N'-dioxide, with metal ions is comparatively less2,3.Thus, it is worthwhile to study the ligational behaviour of 1,10-phenanthrolineN,N'-dioxide (Phen07.) with oxovanadium(IV).
EXPERIMENTAL
The Iigand Phen02 was prepared from 1,10-phenanthroline by the method des-cribed for 2,2'-bipyridyl N,N'-dioxide,3 while the Lewis acids were obtained asreported in ref. 4.
The complexes were prepared by mixing warm acetone solutions of oxovana-dium{IV) salts with PherrOj in the same solvent. In some cases, the preci pitati on ofthe complexes occurred on mixing the solutions while in the others, the precipitateswere obtained on keeping the mixtures on water bath for 5 minutes under stir ring.The solid products were collected, washed with ether and dried in vacuo over P205•
AnalyticaI procedureVanadium metal in all the complexes was estimated by EDTA titrations using
Erichrome Black-T as indicator and was confirmed by igniting the complexes inair and estimating the metal as V205. The halides in the complexes were estimatedby Volhard's method. The perchlorate was determined by the method of Kurz et al."All other physico-chemical studies of the complexes were made as reported earlier."
RESULTS AND DISCUSSION
The interaction of oxovanadium(IV) salts with PherrO, results in theformation of compounds of the general composition VOX2 . PherrO, (X = CLBr, I, NCS, N03 or C204 )and VO(Cl04h . 2Phen02. The analytical data aregiven in Table I. The compounds are quite stable and can be stored for a long
* Author for correspondence.
eo >I>-
(j)
TA
BLE
I
Ana
lytic
al,
Con
duct
ivity
and
Par
tial
IRD
ata
(cm
-1)
for
VO
++
Che
late
sof
Phe
n02
Foun
d(C
alcd
.)/O
/oQm
Ave
rage
Mol
.W
t.v
(N=O
)c:
5(N
-O)
v(M
-O)
Com
poun
doh
m1
ern"
(For
mul
aV
NA
nion
mol
'"W
t.)
Phen
0213
10s
855s
?J-
--
--
-12
80s
(':
845m
420m
:..V
OCh
.Phe
n02
14.3
97.
8120
.02
3.93
342
1280
so
(14.
57)
(8.0
0)(2
0.28
)(3
50)
1265
m:.. ;0
VO
Br2
.Phe
n02
11.4
26.
1235
.87
4.29
431
1290
m85
0m42
5m:;J :..
(11.
61)
(6.3
7)(3
6.44
)(4
39)
1270
mt-< ;J>
VO
h'Ph
errO
j9.
415.
0646
.82
5.33
528
1290
m84
5w43
0mZ
(9.5
6)(5
.25)
(47.
65)
(533
)12
80sh
tJ 0V
OC20
4.P
hen0
213
.73
7.44
-5.
1935
812
80s
850m
427w
(fJ(1
3.89
)(7
.62)
(367
)12
70sh
Z28
.05
5.16
1270
s85
0m43
0mo
VO
(Cl0
4l2
.2Ph
en02
7.21
3.87
233
~(7
.39)
(4.0
5)(2
8.84
)(6
90)
1240
m
VO
(NO
sl2
.Phe
rrO
',12
.43
13.6
9-
3.62
397
1280
m85
2m42
5m(1
2.65
)(1
3.89
)-
(403
)12
70sh
VO
(NCSl
2.P
hen0
212
.72
14.0
228
.82
5.26
387
1290
m86
0m42
0m(1
2.91
)(1
4.17
)(2
9.36
)(3
95)
1275
w
V-COMPLEXES 947
time. The compounds are fairly soluble in common organic solvents. Theelectrical conductances measured in nitrobenzene at room temperature (32°C)are consistant with the non-electrolytic nature of halo, pseudohalo, oxalatoand nitrato complexes, while the perchlorate complex is 1 : 2 electrolyte.
The room temperature magnetic moments of the complexes are in therange 1.72-1.80 B. M. These values correspond to one unpaired spin pervanadium atom, demonstrating the tetravalency of vanadium in the complexesand also the absence of metal-metal interaction between vanadium atoms.?
Infrared SpectraTable I records important IR bands for the ligand and the complexes.
In the IR spectra of the free ligand two (N-O) bands at 1310 and 1280 crn"have been observed-". These bands were shifted to lower frequencies uponcomplex formation. The decrease in the frequency of the V (N-O) vibrationis attributed to O-O chelation in PherrOj. Absorption of strong intensity at855 cm" has been assigned to NO bending mode, and from the tabulated datait appears that this absorption changes only slightly on complexationt=. Thisfurther supports oxygen linkage between metal and ligand. In the far IRregion the metal-ligand vibration is tentatively assigned to v (V-O) mode.
The bands due to the v {V=O) vibration occur in the 980-960 crn? region.These- values are in the range observed for monomeric VO++species in all thePherrO, complexes of oxovanadium(IV)1. However, it may be pointed out thatthe lower values of v (V=O) normally inferred" the polymeric nature of thecomplexes. But recent views indicate that solid state effects" and electron--withdrawing groupa'? can also cause a lowering of the v (V=O) frequency.
The ionic nature of the perchlorate group may be suggested by the pre-sence of a fairly broad v3, band at 1090 cm" and v, band at 625 cm" 4,11. Thethiocyanato complexes show three bands at 2080 (v C= N), 850 cm" (v C-S)and 460 cm? (O'NCS). This may be taken as an evidence of the bonding of thethiocyanate through nitrogen in the VO++cornplex'". The bidentate nature ofthe coordinated oxalate group, bonded covalently to the VO++moiety, isrevealed by the presence of V7, VI and v2 bands at 1715, 1650 and 1360, respec-tively!". In the IR spectra of VO(N03h' PhenN02, the bands appearing at1575 (VI), 1260 (V2), 1030 (V3) and 805 (V4) indicate the covalent nature of thenitrato groups in the complex-". The two combination bands appear at 1770and 1750 cm-I. By applying the 'Lever separation method!" the separation of20 cm" in this case suggests the monodentate nature of the nitrato groups.
Electronic SpectraThe electronic spectra of the complexes in CH3CN in the visible range
were taken. In all the chelates the bands occur in 12500-12800 cm" regionwith a shoulder in 15300-15700 cm" region. These bands are due to d-dtransition spectrum and can be assigned to dxy ~ dxz>dyz and dxy ~ dx'_/transitions, respectively. The band due to dxy ->- dz2 seems to have been maskedby the intense charge-transfer bands occuring in the UV region!",
In conclusion, in all these chelates the coordination number of vanadiumis five and the penta-coordinated oxovanadium(IV) complexes can have a tetra-gonal pyramidal structure.
( .
TABLE
II
Thermoanalytical
Results
Obtained
for
the
VO++
Cheuiies
ofPhen02
<:o ~ 00
Sample
Residual
Com
pound
Wto
mass
mg
mg
VOCb.Phen02
28.72
7.07
VOBr2
.PhenO
s30.16
5.76
VO(NCSh
.Phen02
27.32
6.17
VO(N03h
.Phen02
26.92
5.66
VOC204.Phen02
29.12
6.75
Massloss
(%)
140-220oC
280-
375O
C
Theor."
Exp.
Theor.b
Exp.
30.28
32.16
60.57
62.15
24.14
25.95
48.29
50.06
26.83
28.16
53.67
55.02
26.30
27.92
52.60
54.06
28.88
30.06
57.76
59.06
Residue
o/~
~53
00C
~Theor.e
Exp.
;.. o ;.. :ti26.00
24.65
:::: ;..20.72
19.12
l' ;..23..03
22.59
z tj22.58
21.06
0 ff)
24.79
23.19
H z o ~•Calculated
forloss
of.0.5
moleof
Iigand.
bCalculated
fortotalloss
ofIigand,
eCalculated
asV20S.
V-COMPLEXES 949
Thermal Studies
The results of thermal analysis of VO (IV) complexes are presented inTable II. The t. g. and d. t. curves of VO(IV) chelates of Phen'O, do not showthe presence of water molecules, either in or out of the coordination sphere.The t. g. curves show that all the chelates complete their decomposition pro-cess according to the following schemes:
VOX2 • PherrO, ~ VOX2 • O . 5Phen02 ~ VOX2 -? [VOz] ~ VzOs(X = Cl, Br, NCS, N03 or C204)
REFERENCE S
1. N. M. Karayannis, A. N. Spe,ca, D. E. Chasan, and L. L. Pytlew-s k i, Coord. Chem. Rev. 20 (1976) 37.
2. A. K. S r iva s t a v a, S h ash i S h a rrna, and R. K. Ag a r w a 1, Inorg.Chim. Acta 61 (1982) 235.
3. R. K. Ag a r w a 1, G y ane n d r a S i n g h, M. S r iva s t a v a, and A. K.S r iva st a v a, Thermochim. Acta 73 (1984) 243.
4. R. K. Ag a r w aland G y ane n d r a S i n g h, Thermochim. Acta (In Press).5. E. K u r z, G. K o b e r, and M. B e r l, AnaLyst Chem. 30 (1958) 1983.6. R. K. A g a r w a 1, A. K. S r iva s t a v a, and T. N. S r iva s t a v a, Tran-
sition Met. Chem. 5 (1980) 95.7. J. SeI b i n, Chem. Rev. 65 (1965) 153.8. R. L. F a r m e r and F. L. U r b a c h, Inorg. Chem. 13 (1974) 587.9. M. P a s qua t e, F. Mar c het t i, C. J. Flo ria n i, and S. Me r 1i n o,
J. Chem. Soc., DaHon Trans. (1977) 139.10. H. A. K u s k a and P. H. Y a n g, Inorg. Chem. 16 (1977) 1938.11. S. K. Ma dan and A. M. D o n o h u e, J. Inorg. NucL Chem. 28 (1966) 1303.12. J. L. B u r mei ste r, Coord. Chem. Rev. 1 (1968) 205; 3 (1966) 225.13. G. Du r g a Pra sad and C. C. Pat e 1, Indian J. Chem. 11 (1973) 1300.14. S. K. Sa h n i and S. K. S an gal, Synth. React. Inorg. Met.-Org. Chem.
8 (1978) 291.15. A. B. P. Lever, E. M o n tova n i, and B. S. Ram a s w amy, Can. .T.
Chem. 49 (1971) 1957.16. D. N. Sat h y ana ray ana and C. C. Pat e 1, Indian J. Chem. 5 (1967) 360.
SAŽETAK
Spektrometrijsko termometrijsko istraživanje kelatnih kompleksa vanadil-Ienas 1,10-fenantrolin N,N'-dioksidom
R. K. AgarwaL i G. Singh
Interakcijom vanadil-iona s 1,10-fenantrolin-N,N'-dioksidom (Phen O-) nastajuspojevi opće formule VOX2 . PherrOs (X = Cl, Br, I, NCS, N03 ili C20J) i VO(CI04l2 .. 2Phen02. Nastalim kompleksima snimljeni su IR i UV/VIS spektri, te je određenmagnetski moment i molarna provodnost. Kompleksi su također podvrgnuti terrnič-koj (TG i DT) analizi, koja je pokazala odsutnost molekula vode unutar koordina-cijske sfere centralnog iona i izvan nje.