Synthesis and spectral studies of iron(III) and iron(II) complexes with 2,3-disubstituted quinazolin -4(3 H)-ones (2000)

A number of Fe(III) and Fe(II) complexes of some 0-N-0 donors and bidentate 0 -0, and 0-N donors in the form of 2,3disubstituted quinazolin-4(3H)-ones have been synthesized and characterized based on analytical, conductivity, thermal, magnetic and infrared, electronic and Mossbauer spectral data. The analytical data of Fe(III) complexes with all the ligands with the exception of 2-methyl-3-carboxymethyl quinazolin-4(3H)- one (MCMQ) and 2-phenyl-3-carboxymethyl quinazolin-4(3H)- one (~CMQ), and all the complexes of Fe( II) show I :2 (metal:ligand) stoichiometry. However, Fe(III) complexes of MCMQ and PCMQ are in I :3 stoichiometry. The IR spectral d ata of complexes indicate that the ligands MHBQ and PHBQ act as uninegative tridentate and MCMQ and PCMQ act as uninegative bidentate ligands. The ligands viz 2-methyl-3-amine quinazolin-4(3H)-one (MAQ), 2-phenyl-3-amine quinazolin-4(3H)- one (PAQ), 2methyl-3-uramino quinazolin-4(3H)- one (MUQ), 2-phenyl-3uramino quinazolin-4(3H)- one (PUQ), 2-methyl-3-thiouramino quinazolin-4(3H)- one (MTUQ) and 2-phenyl-3-thiouramino quinazolin-4(3H)- one (PTUQ) act as neutral bidentate ligands. Octahedral geometry has been proposed for all the complexes based on electronic and Mossbauer spectral data. Our earlier reports 1 ' 2 on Co(ll), Ni(II), Cu(II), Ru(II) and Pt(II) ions with substituted quinazolines indicate that these compounds act as bidentate with Co(II), Ni(II) and Pt(II) and tridentate with Cu(II) and Ru(II) metal ions. In continuation of our earlier work, we report herein the synthesis and characterization of Fe(III) and Fe(II) complexes with various 2,3disubstituted quinazolines where R = methyl/phenyl and X = 2'-hydroxybenzalamino (MHBQ/PHBQ) (1) carboxymethyl (MCMQ/PCMQ), amme (MAQ/ PAQ), uramino (MUQ/PUQ) and thiouramino {MTUQ/PTUQ) (2) . The analytical, conductivity, thermal, magnetic, infrared, electronic and Mossbauer data are reported to characterize these complexes. Experimental All the chemicals and solvents used were of A.R. (BDH), G.R. (S Merk) or of high purity grade. The ligands were prepared as reported in Iiterature 3 - 5 . The purity of these compounds was checked by TLC and MP determinations. The analytical data for C, H, N and S for the ligands and their complexes were obtained using a Carlo-Erba CHNSO analyzer. The metal content in the complexes after heating to decomposition temperature were determined using a spectrophotometric method. Molar conductivity of the complexes in DMF (I o- 3 M) were measured using a Digisun digital conductivity meter model DI-909. The thermal data of the complexes were obtained using a Stanton thermobalance at the IICT, Hyderabad. The magnetic susceptibility measurements of the complexes in solid state were made at room temperature by the Gouy method using Hg[Co(NCS)4] as calibrant. The infrared spectra of the ligands and their complexes in nujoi/KBr/Csl pellets were recorded using Shimadzu model 8201 (PC) fourier transform spectrophotometer with inbuilt software Hyper-IR Pentium computer. The electronic spectra of the complexes in DMF were recorded on a