Indian Journal of Chemistry Vol. 30A, October 1991, pp. 881-885 Synthesis, characterisation and spectral (IR, 1H, 13eand 119SnNMR) studies of some organotin(IV) complexes of 4-acyl- 2, 4-dihydro- 5-methyl- 2-phenyl- 3H-pyrazol- 3-one A Jain, S Saxena & A K Rai· Department of Chemistry, University of Rajasthan, Jaipur 302 004 Received 7 February 1991; revised and accepted 23 May 1991 I I Some organotin(IV) complexes of composition Me2SnCI2_n[(R)COC: CON(C6Hs)N: CCH3}nand R;Sn((R)COC: CON(C6Hs)N: CCH3] (where R=-CH3, -C2Hs, -C6Hs and p-ClC6H4, R' = n-C4H9, -C6Hs and n = 1 or 2) have been synthesized and characterised on the basis of elemental analyses, mole- cular weight measurements and spectral studies: The probable structures have been assigned. Organotin(N) complexes with a variety of ligands having nitrogen and oxygen donor atoms have been reported 1-8.In view of the reported biological activ- ity of pyrazolone derivatives of cyclopentadienylti- tanium(N)9, parallel studies have been undertaken with organotin(N) chlorides. Materials and Methods Me2SnCI2' Bu3SnCI and Ph3SnO (all Pluka rea- gents) were distilled before use. All the solvents were dried by standard methods. Stringent precau- tions were taken to exclude moisture. The following ligands were synthesized by the procedure reported by Jensen10 and characterised on the basis of ele- mental and spectral analysis: where R = -C6Hs[BMPPOH]; p-CIC6H4[CMPPOH]; -C2HS[PMPPOH]; -CH3[AMPPOH] Melting points were determined in sealed capilla- ries under dry air. Tin was estimated gravimetrically as tin(N) oxidell and chlorine volumetrically using Volhard'sl1 method. Molecular weight measure- ments were carried out on a Knauer vapour pres- sure osmometer using chloroform solutions at 45°C. IR spectra were recorded in the range 4000-200 cm -1 on a Perkin Elmer 577 spectrophotometer us- ing CsI pellets or as nujol mull. NMR (1H, 13C & 119Sn)spectra were recorded in CDCl3 solutions on a JEOL FX 90Q (90 MHz) spectrometer. Synthesis of his-(4-propionyl- 2,4-dihydrlr 5- methyl- 2-phenyl- 3H-pyrazol- 3-onato)dimethyl- tin(IV) A TIfF solution of Me2SnCl2 (0.50 g, 2.29 mmol) was added drop by drop to a reaction mixture, ob- tained by the interaction of sodium methoxide (0.10 g, 4.57 mmol Na in - 5 ml of methanol) and the li- gand (1.05 g, 4.57 mmol) dissolved in dry TIfF. The reaction mixture was refluxed for - 6 hr and the precipitated sodium chloride was filtered off. On stripping off the volatile fraction under reduced pressure, a yellow coloured solid was obtained in quantitative yield. The product was recrystallised from chloroform/hexane mixture in -70% yield. The melting point of this derivative along with those of others is given in Table 1. Results and Discussion The sodium salts of the enolic form of ligands, 4-acyl- 2, 4-dihydro- 5-methyl- 2-phenyl- 3H-pyra- zol-3-one [AcMPPOH], interact with (CH3)2Sn02 in 1 : 1 and 2: 1 molar ratios to yield the corre- sponding dimethyltin(N) complexes. TIfF nAcMPPONa + (CH3hSnCI2 • (CH3hSnCI2_n(OPPMAc)n + nNaCI ~ (where Ac = benzoyl, p-chlorobenzoyl, propionyl, acetyl and n= 1,2) 881