Synthesis and Characterization of Cobalt ( II ) , Nickel ( II ) and Copper ( II ) Complexes with Nitrogen-Oxygen Donor Ligand

The complexes of ML2 were synthesized where M= Co(II), Ni(II) and Cu(II) and L= 2-Butyl thioquinazoline 4 (3H)semicarbazone (BTQS). The ligand have been synthesized by condensation of thioquinazoline-4(3H)-one with semicarbazide hydrochlande characterized by molar mass, elemental analysis, Infrared spectra, electronic spectra, magnetic susceptibility and molar conductance measurements. The ligand BTQS acts as neutral bidentate chelating agent and coordinated to metal ions through azomethine nitrogen and carbonyl oxygen of semicarbazone moiety. The remaining Coordination centres are satisfied by anions such as Cl-, Br-, Iand NO3 -.


Preparation of the Ligand :
Ethanolic solution of 2-butyl thioquinazoline 4(3H) one (0.01m) was treated with semicarbazide hydrochloride (0.01 m) dissolved in minimum amount of sodium acetate in ethanol.The resulting mixture was heated for 2 and half hour with occassional stirring.The product crystallized from ethanol and dried.m.p. 263±1 o C. Yield 65%.

Preparation of the complexes
The complexes of Cu(II), Co(II) and Ni(II) have been prepared by reacting solution of metal halides with solutions of the ligand BTQS in molar ratio 1:2.The solid coloured complexes which was separated on cooling were filtered, washed with ethanol, dried in oven.Yield in all cases 60-65%.

I.R. Spectra
IR spectra of the ligand and complexes were recorded on Perkin Elmer Spectrophotometer Model 577 using KBr disc.
The IR spectra of the ligand exhibit strong and broad band at 1560 cm -1 assignable [23][24][25] to ν C=N .The band is shifted to lower wave number after complex formation, proposes involvement of azomethine N in the bonding with metal ions.The appearance of a band in far IR region at 425-395 cm -1 .In the complexes assignable [24][25][26] to ν M-N .The IR spectra of the ligand exhibits strong and broad band at 1760 cm 1 assignable [25][26][27][28] to ν C=O .This band undergoes to shift after complex formation, proposes coordination of metal ion through carbonyl oxygen.It is further supported by the appearance of a new far IR band at 525-505 cm -1 in the complexes which is assignable [24][25][26] to ν M-O .The linkage with halogen is indicated by the appearance of another band in the far IR region 320-280 cm 1 assigned [24][25][26] to ν M-X (X= Cl -, Br -or I -).The coordination with halogen is supported by the low molar conductivity of the complexes in the range 11.2-13.7 ohm -1 cm 2 mol -1 .
Nitrate complexes show characteristic medium intensity bands at 1360 and 1180 cm -1 with a separation 140 cm -1 due to monodentate linkage of nitrate groups.Combination band at 1660 cm -1 and 1640 cm -1 with a separation of 20cm -1 conforming the monodentate behavior of the nitrate 29 group.

Electronic Spectra and Magnetic Susceptibility of the Complexes
The Co(II) complexes exhibit two spectral bands in the region at 13400-12860 cm -1 and 2100-20300 cm -1 assigned to the transitions, 4 T 1g (F) → 4 A 2g (F) and 4 T 1g (F) → 4 T 1g (P) proposing octahedral 30,31 geometry.The proposed geometry of Co(II) complexes are further supported by the high magnetic susceptibility value in the range 4.92-5.12B.M. The Ni(II) complexes display three spectral

Table 1 : Physical Analysis of Ligands and Its Complexes Compounds Molar % Analysis found (calculated) µ eff
DT = Decomposition Temperature