Studies on some mixed ligand complexes of Ni(II)

Notes IO.O6

--

Cd(ll) 4 . 3 1 [Cd(x)] 3.61,[Cd(x)2] 2.{,~ .[Cd(x)3]

[Cd(v) 349,[Cd(x)(y)] 2'75~[Cd(x)2(y)] ~"

t;

1-

1.36

~, °

I o.aa

603

The values are: log//11 5.94 (Calc.), 6.43 (exptal), log ~2~ 8.98 (Calc.), 9.18 (exptal.), log ,St~ 7.45 (Calc.), 7.45 (exptal.). The slightly higher experimental values found can be explained in terms of electrostatic and steric factors as concluded by other workers [8]. Department of Chemistry University o[ Delhi Delhi-110007 India

ANITA RANI AGGARWAL HARISH KUMAR ARORA K. B. PANDEYA R. P. SINGH*

[Cd(y)2] 3.15 [Cd(x)(y)2]

REFERENCES

~[Cd(yh] z.ol From the above scheme the following conclusions are drawn: (1) The tendency of [Cd(gly)]+ and [Cd(ox)] to add a second ligand can be compared. It is easier for (gly) to add to [Cd(ox)] than to [Cd(gly)]+. Thus formation of the mixed complex is favoured. (2) The tendency of the saturated mixed complex [(Cd(gly)2(ox)]to substitute ox by gly is given by log K = 0.88, while there is no tendency to substitute fly by ox. This observation is in line with the weaker nature of the (ox) ligand. The stability constants of mixed complexes have been estimated theoretically using the method of Watters and De Witt[7]. *Author to whom correspondence should be addressed.

1. G. Nageswara Rao and R. S. Subrahmanya, Proc. Ind. Acad, Sci. 60, 165 (1964). 2. D. D. De Ford and D. N. Hume, J. Am. Chem. Soc. 73, 5321 (1951). 3. W. B. Schaap and D. L. McMasters, J. Am. Chem. Soc. 83, 4699 (1961). 4. I. Leden, Z. Phys. Chem. 188, 160 (1941). 5. S. L..lain, Jai Kishan and R. C. Kapoor, Indian J. Chem. 18A, 133 (1979). 6. G. Brookes and L. D. Pettit, Z Chem. Soe. (Dalton) 1918 (1977). 7. J. I. Watters and De Witt, J. Am. Chem. Soc. 82, 1333 (1960). 8. E. D. Hughes, C. K. Ingold, S. Patai and Y. Pocker, J. Chem. Soe. 1206 (1957).

J. inorg, nucl. Chem. Vo[. 43, pp. 603-605 Pergamon Press Ltd., 1981. Printed in Great Britain

0022-1902/81t0301~603/$02.00[0

Studies on some mixed ligand complexes of Ni(II) (Received 2 July 1980; received[or publication 25 July 1980) Mixed ligand complexes of Ni(II) with salicylic acid as primary ligand and pyridine, ,O-picoline, oxine and nicotinic acid as secondary ligands have been synthesised by the method of Khadikar et al.[1]. The compounds have been analysed and structures have been suggested on the basis of elemental analysis, magnetic susceptibility, IR and reflectance spectral studies. The results of elemental analysis indicated that the mixed ligand complexes have the composition ML2X2'2H20 and MLX'2H20. In the former case X=pyridine and /3-picoline while in latter it is oxine and nicotinic acid. The results obtained from the reflectance spectra and magnetochemical studies are recorded in Table 1 while the band assignment and the spectrochemical parameters, e.g. crystal field splitting energy 10Dq, Racah parameter and nephelauxatic coefficient are given in Table 2. The perusal of Table 1 shows that in the case of Ni(SAL)2Pico22H20 and Ni(SAL)(Nico).2H20 the Yt band is not observed, however its presence in the near IR has been indicated by the upward trend in the corresponding reflectance spectra. The theoretical band assignment has been made as described by Lever[2]. The ratio Y2/Ylranges between 1.56 and 1.68, which is characteristic of all the Ni(II) complexes having pseudo octahedral environments, suggesting thereby, strong T,~ term interactions [3]. In case of Ni(SAL)2.2H20, Ni(SAL)2"Pico2"2H20 and Ni(SAL)(Nico).2H20 a weak shoulder is observed at about 14,000 cm -t. This is probably due to the spin forbidden transition ~A2~-~tE~ as suggested by Jorgensen[4]. In additioa to 10Dq and B values, the nephelauxatic coefficient, ~, has also been

calculated. The values are in good agreement with those reported for octahedral Ni(II) complexes [3]. Based on the values of B, the nephelauxatic series is as under: Ni(SAL)(Oxine).2H20 > Ni(SAL)2'Py2"2H20 > Ni(SAL)2'2H20 > Ni(SAL)2'Pico2'2H20 > Ni(SAL)(Nico).2H20. The observed magnetic moments for all the complexes are in the range expected for Ni(II) octahedral complexes. The 3A2~ ground term can generate no orbital contribution. However, spin orbit coupling mixes the first excited 3T2g into the 3A2~term, the mixing-in-effect being expressed quantitatively as:

where • is the spin orbit coupling constant. Since ,~ is negative for Ni(II) complexes it follows that moment will be higher the lower the 10Dq i.e. weaker the ligand is. The experimental magnetic moments lie usually within the range 2.9-3.3 B.M. Our moments all fall within the range 3.1-3.6B.M. The observed deviation from the spin only value could be due to second order Zeeman effects between the ground state and the highest ligand field terms. IR spectra of the complexes show the characteristic bands of hydroxy acids and the secondary ligands. In case of the oxine and nicotinic acid complexes the bands in the neighbourhood of 800 cm-~ indicates the presence of coordinated water[7]. In the

Light green Light green Light green Yellow Light green

N£(SAL)2.B~O

Ni(SAL)s.py~.2~O

NI(SAL)2.PicO2.~H20

Ni(SAL)(Oxlne).2~O

Ni(SAL)(Nico).2~O

1.

2.

3.

4.

5.

3.550

3.245

3.687

5.467

5.149

B.M.

520, 450, 600, 680

390, 6OO, 685, 840, 94O

335, 615, 665

530, 410, 650, 915

510, 410, 745, 920

r~

Ni( SAL)2-PY2-2H20

NI(SAL)2-Pico2"2~O

Ni(SAL) (Oxine) .2H20

NI(SAL) (Nico) .2H20

5.

4.

5.

51250

26750

29850

503O3

52258

1.682

1.568

1.676

1.635

0.9~O 1.065 0.860 1.417 O.821

1~7 1154 758 1205

Dq

1181

for gaseous ion I. 1080 cm-1 [Ref. 6].

16667

16667

16260

17870

10 Dq for aquo ion ~ 8500 cm-I [Ref.5] and B

9910

10658

9754

10929

18070

1.665

2.

Vl

1O869

(VS)

Ni(SAL)2-2~O

(V2)

1.

(v1=1o Dq)

5~g-~ ~T2g 3~g-~ 3~lg(F) 3~g-~ ~Tlg(P) v_~2

S.No. Complex

a

1.116

0.70~

1.O50

0.951

1.09~

31250, 22222, 16667, 14706

25641, 16667, 14598, 11905, 10638

29850, 16260, 15039

30503, 24390, 15384, 10929

5~58, 204C8, 154~, 10869

Table 2. Principal band positions and spectrochemical parameters

COI.I~Ir

S.No,

c~le.x

Table 1. Magnetic moments and observed band positions

Zo

605

Notes other cases the bands observed at about 600cm -~ may be assigned for the presence of lattice water [8]. In all cases an M-O band is observed at about 400 cm-L In the high frequency region the pyridine vibrations show very little shift upon complex formation. However, those of inplane and out-plane ring deformations are shifted to higher frequencies and are observed at 640 and 430cm -~ respectively. The M-Py and M-Pico stretching vibrations occur at 230 cm -l. The band in the neighbourhood of 500 cm -l, may be regarded as the evidence of bonding of nitrogen to the metal ion [8].

Lecturer, Chemistry Dept. Holkar Sc. College, Indore India Reader, Chemistry Dept. University of Indore, Indore India

C.P. SAXENA P.V. KHADIKAR

REFERENCES 1. P. V. Khadikar, R. L. Ameria, N. G. Kekre and S. D. Chauhan, J. lnorg. Nud. Chem. 35, 4301 (1973). 2. A. B. P. Lever, Inorganic Electronic Spectroscopy. Elsevier, Amsterdam (1%8). 3. A. B. P. Lever, Coord. Chem. Rev. 3, 119 (1%8). 4. C. K. Jorgensen, Act. Chem. Scand. 10, 887 (1956). 5. C. S. G. Phillips and R. J. P. Williams, Inorganic Chemistry, Vol. 2. Pergamon Press, Oxford. 6. B. N. Figgis, Introduction to Ligand Fields. Wiley, New York (1966). 7. J. Fujita, K. Nakamoto and M. Kobayaski, J. Am. Chem. Soc. 78, 3%3 (1956). 8. K. Nakamoto, IR Spectra o[ Inorganic and Coordination Compounds, pp. 151, 167. Wiley-Interscience, New York (1970).

Z inorg, nucL Chem. Vol. 43, pp. 605-606 Pergamon Press Ltd., i981. Printed in Great Britain

0022-190218110301.-~051502.0010

Synthesis and c h a r a c t e r i z a t i o n of copper maleate complexes

(Received 18 June 1980; receivedfor publication 25 July 1980)

Maleate can in principle be ionic, co-valent monodentate, covalent bidentate or act as a bridging ligand. Although copper complexes of maleic acid of various composition have been synthesized[I-5] the properties of copper maleato complexes have not been studied. We have synthesized normal and acido complexes of Cu(II) with maleic acid (Mal'H)2 of formulae [Cu(Mal)(H20)] and [Cu(Mal.Hh(H2Oh] and characterized by magnetic susceptibility, X-ray diffraction, IR spectral and derivatographic studies. The oxidation of maleic acid, in presence and absence of Cu(II), by Cr(VI) in 6 M H2SO 4 has also been studied.

EXPERIMENTAL Synthesis. Maleatoaquo Cu(II), [Cu(Mal)(H20)](I) and bis (hydrogen maleato) tetraaquo Cu(II), [Cu(MaI-H)2(H~Oh](II) were prepared at room temperature by dissolving freshly prepared Cu(lI) hydroxide in an aqueous solution of maleic acid in 1:1 and 1:2 molar ratio respectively. Very light blue crystals of (I) and deep blue crystals of (II) were obtained. The molecular formulae have been given on the basis of chemical[6, 7] and X-ray analysis. Characterization. Magnetic moments were determined by Gouy method and dimagnetic corrections were made using Pascal's constants. IR spectra in the range 600-4000cm -~ were recorded in KBr disc on a Perkin-Elmer 700A spectrophotometer. X-Ray diffraction measurements were done using Weissenberg photographs. Their thermal discomposition has been studied using the system of Paulik, Paulik and Erdey. 600 rag of [Cu(MaI-H)2(HzO)4] was heated at a rate of 8°C/min upto 800~C in static air. Oxidations of M/60 K2Cr207 with M/120 maleic acid and M/60 K2Cr207 with M/2~ [Cu(MaI.H)2(H20)4] in 6 M H2SO4 were carried out [81. RESULTS AND DISCUSSION

Magnetic susceptibility, The room temperature magnetic

moment values of complexes (I) and (II) are 2.00 and 1.% B.M. The values indicate that complexes (I) and (II) have normal magnetic moments of a spin only value for divalent copper ion. X-Ray crystal diffraction measurements. The crystals of (I) are monoclinic with a = 8.77, b = 7.88, c = 5.36 A, y = 125.1°, space g r o u p P2 , Z = 2, D m = 2.08 a n d D c = 2.14. Its m o l e c u l a r weight

has been found to be 195.6 with one molecule in the cell. Here the copper atom has a square pyramidal five fold coordination. The donors in the basal plane are two oxygen atoms of a maleate group forming a seven membered chelate ring and two oxygen atoms of two different maleate groups. The ligand at the apex is a water molecule. The crystals of (II) are also monoclinic with a = 3.59, b = 18.80, c =9.70/k, -/=93.25°C, space group I2/m, z=2, Dm 1.86 and Dc = 1.859. The molecular weight is 365.7 with one molecule in the cell. The metal is six fold coordinated by oxygen atoms forming a distorted octahedral coordination sphere. The maleic acid functions as monodentate ligand. IR spectra. There is a lowering of the carbonyl frequency from 1718cm -t in maleic acid to around 1660cm -t in (I) and to 1652cm -~ in (It). The C-O stretches which appear at 14401470 cm -I in the free acid appears in the range 1430-1450 cm -t in (I) and 1428-1449cm -t in riD. Like the higher frequency C=O, generally the C-O stretch is slightly affected in the complexes. In maleato complexes, the C--O stretching mode occurs in a slightly lower region when coupled to those of maleic acid. The asymmetric C--O stretch is found at 1555 cm -~ in the acid maleate ion, which has a linear symmetrical hydrogen bond between two carbonyl oxygens and the C=O stretching mode was observed to couple with the C-O stretching vibration. Since the effect of hydrogen bond formation and metal ion coordination on the carbonyl bands is expected to be identical in this case, a similar assignment could be made for the higher asymmetric C=O stretching frequency in the maleato complexes.