Indian Journal or ChemistryVol. 21A, October 1982. pp. 1004-1006

Organoxytitanium(IV) & Organotin(IV)Derivatives of Schiff Bases Derived from

S-Benzyldithiocarbazatef

S K PANDIT, (Mrs) SARADA GOPINATHAN &C GOPINATHAN*

Inorganic Chemistry Division. National Chemical Laboratory.Pune 411008

Received 30 January 1982; revised and accepted 10 May 1982

Penta- and hexa-coordinated compounds of titanium(IV) and.tin(lY) with schiff bases derived from S-benzyldithiocarbazate ando-hydroxyacetophenone, 5-chlorosalicylaldehyde or 5-bromo-salicylaldehyde have been prepared and characterised.

Jenson I was the first to prepare Ni(II) complex ofdithiocarbazic acid. Later, Akbar Ali et al.' 4

reported Cu(I1), Ni(ll), Co(Il) and Pd(II) complexeswith ONS donor tridentate schiff bases derived fromdithiocarbazate. Recently, a few reports":" haveappeared on the synthesis of triorganotin(lV)complexes of schiff bases derived from S-benzyl- andS-methyl-dithiocarbazates.

New chelated titanium and organotin compoundswith schiff bases derived from S-benzyldithiocarbazateand o-hydroxyacetophenone, 5-chlorosalicylaldehydeor 5-bromosalicylaldehyde are reported in this note.

The solvents were carefully purified, thoroughlydried and distilled before use. Reactions wereconducted under dry nitrogen. o-Hydroxyacetophe-none-S-benzyldithiocarbazate (HyAcSBDTC-H2) wasprepared using hydrazine hydrate, o-hydroxyaceto-phenone. carbon disulphide and benzyl chloride. Theyellow crystals thus obtained melted at 152'. S-Benzyl-/I- N -(2-hyd roxy- 5-chlorophenyl)met hy lendi thiocar-bazate (CISaISBDTC-H2; m.p. 186') and Svbenzyl-ji-N-(2-hydroxy-5-bromophenyl)methylendithiocarba-zate (BrSaISBDTC-H2; m.p. 195) were also preparedsimilarly.

Titanium compounds: (a) (LH)TiC/3- TiCI4 (1.90 g;0.01 mol) in benzene (10 ml) was added slowly toHyAcSBDTC-H2 (3.16g; 0.01 mol) dissolved inbenzene (30 rnl), and the mixture was refluxed forremoving HC\. The red product separated was filtered.washed with hexane and dried in canto; yield, 3.30 g(70~:,) [Found: Ti, 10.31; CI. 22.30; C, 40.35; H, 3.02.Calc. for(C Ii,H ,sN20Sz)TiCl3: Ti. 10.22;.0,22.69; C,40.89; H. 3.19\,].

(b) LTi(OPrh and L2Ti Freshly distilled titaniumtetraisopropoxide (0.71 g: 0.0025 mol) was mixed with

tNCL Communication '0. 2955.

1004

HyAcSBDTC-H2 (0.79 g; 0.0025 mol) in benzene (50m\) and the mixture refluxed using a partial refluxcondenser; the liberated isopropanol was estimated bygas chromatography. The contents were thencentrifuged and the solution concentrated. The redsolid obtained was washed with hexane-benzenemixture and dried in racuo, The compound was solublein hot benzene; yield, 1.10 g (90~-.,)[Found: Ti, 10.40; C,54.25; H, 5.37. Calc. for (C 16H I~N zOS2)Ti(C3H70h;Ti, 10.00, C. 54.95; H. 5.83'',;].

Compounds of the type L2Ti were similarlyprepared.

(Sa1)2 TiL- Bis(salicylaldehydato)titanium diiso-propoxide (1.02 g; 0.0025 mol) was reacted withHyAcSBDTC-H2 (0.79 g; 0.0025 mol) in benzene. Theproduct, isolated as in (b), weighed 1.30 g (90/,,)[Found: Ti. 7.99: C, 59.34: H, 4.00. Calc. for(CI6H,4N20S2)Ti(C7H502)2: Ti, 7.95; C, 59.57: H. 3.g0".,].

Other schiff bases and titanium derivatives of otherbidentate chelating ligands reacted similarly (Table I).

Tin compounds: (a) LSnC/2-Sodium salt ofHyAcSBDTC-Hz (1.59 g: 0.005 mol) and stannicchloride (1.30 g; 0.005 mol) were reacted in benzene byrefluxing for 2 hr. The separated sodium chloride wasremoved. solution concentrated to get yellow crystals;yield, 1.90 g (75'\) [Found: Sn. 23.20; Cl. 13.95; C,38.00: H, 2.65. Calc. for (CI6HI4N20S2)SnCI2: Sn,23.56: cr. 14.09; C. 38.11; H. 2.78'/,;].

(h) MCzSnL-Dimethyltin oxide (0.90 g; 0.0055 mol)and HyAcSBDTC-H2 (1.58g, 0.005 mol) were reactedin benzene and the water formed was removedazeotropically. The resultant solution was processed toget an yellow solid: yield, 2.0 g (90%) [Found: Sn,25.20: C. 46.30: H, 4.21. Calc. for (CI6HI4N20S2)Sn-(CH3lz: Sn, 25.68; C, 46.68; H, 4.32~~].

Other tin derivatives listed in Table I were obtainedby similar methods.

The schiff bases derived from S-benzyldithiocarba-zate have the structural formulae I or II.They have a thione (C = S) group and an adjacentimino proton: these conditions are most favourable forenthiolisation of the thione group to the more stable C- SH form 7 However. the IR spectra of the presentligands do not display I'SH at 2570 em --I indicating thepresence of thioketo form in the solid state and insolution. But, in the presence of metal ions theenthiolisation of the schiff bases is considerablyenhanced. With TiCI~. these ligands form monoderivatives:TiCI4 + LH2 .....•(LH)TiCI3 + HCI

--- _ ... _-- ._. ----

Table Titanium and Tin Derivatives of Schiff BasesDerived from S-Benzyldithiocarbazate and o-Hydroxy-acetophenone, 5-Chlorosalicylaldehyde or 5-Bromosalicyl-

aldehyde

Product] rn.p. eC)

>200d170879892108110184152Low meltingLow melting>200d>210d>200d135115. 116170110Low meltingLow meltingLow meltingLow melting230d220d190d12099IgO120Low meltingLow meltingLow meltingLow melting

I (HyAcSBDTC-H)TiClJ2 (HyAcSBDTC)Ti(OPr),3 (HyAcSBDTC)Ti(Sal)24 (HyAcSBDTC)Ti(Acach5 (HyAcSBDTC)Ti(Dbmh6 (HyAcSBDTC)Ti(8 Hqh7 (HyAcSBDTC)Ti(BPHAh8 (HyAcSBDTC)SnCI29 (HyAcSBDTC)SnMe2

lO (HyAcSBDTC)SnBu1II (HyAcSBDTC)Sn Benzyl,12 (CISaISBDTC-H)TiCI"13 (CISaISBDTC)Ti(OPrh14 (CISaISBDTC), Ti15 (CiSaISBDTC)Ti(Salh16 (CISaISBDTC)Ti(Acac),16 (CISaISBDTC)SnCl218 (CISaISBDTC)SnMe,19 (CISaISBDTC)SnBu220 (CiSaISBDTC)SnOct221 (CISaISBDTC)(SnBuJh22 (CISaISBDTC)(SnPhJh23 (BrSaISBDTC-H)TiCIJ

24 (BrSaISBDTC)Ti(OPr),25 (BrSaISBDTC),Ti26 (BrSaISBDTC)Ti(Sal),27 (BrSaISBDTC)Ti(Acac),28 (BrSaISBDTC)SnCI229 (BrSaISBDTC)SnMe,30 (BrSaISBDTC)SnBu,31 (BrSaISBDTC)SnOct232 (BrSaISBDTC)(SnBu3h33 (BrSaISBDTC)(SnPh.lh

t Yellow to red solids; Sal-H = salicylaldehyde, Acac-H= acetylacetone, Dbm-H = dibenzoylmethane. 8Hq-H = 8-hydroxyquinoline. BPH A-H = benzoylphenylhydroxylamine, Me= methyl, Bu = II-butyl, Oct = II-octyl, Opr = isopropoxy,Hy AcSBDTC -H 2= o-hyd roxyacetophenone-S- benzylidit hiocarba-zate, ClSaISBDTC-H 2 =Svbenzyl-Ii- N·{2-hydroxy-5-chlorophenyl)-methylenedithiocarbazate, BrSaISBDTC-H2 = S-benzyl-{i-N-(2-hydroxy-5-bromophenyl)methylendithiocarbazate.

(1)

NOTES

However, when the disodium salt of the ligand reactswith SnCI4, the chelated tin compound LSnClz isobtained. Other chelated titanium derivatives of theligand containing salicylaldehyde, acetylacetone,benzoylacetone, benzoyl phenyl hydroxylamine, etc.,have been prepared by the elimination of isopropoxygroups of substituted isopropoxytitaniums. Theorganotin chelates are obtained by the elimination ofwater in the reaction of organotin oxide/hydroxide andthe ligand in benzene. The titanium and tincompounds are listed in Table I. They are yellow to redsolids, moderately soluble in benzene (except thechloro compounds) and are monomeric (ebullioscopy).

The IR spectrum or the ligand (band positions inern -t) HyAcSBDTC-Hz in nujol shows a strong vN.- H band around 3160; in the chloro- and bromo-derivatives, this band is seen around 3080. The iO - Hmode is lowered and overlaps with I'C - H mode.However, the spectra of the ligands in CCl4 solutionshow vN - H and 1'0 -- H bands at 3350-3320 and3230-3200 respectively indicating hydrogen bonding inthe solid state. The bands occurring at 1610, 1045-1030and 940-920 in the ligand spectra have been assigned toI'C = N8, I'C = S3 and I'N - N respectively.

The spectra of chelated titanium derivatives (exceptthe trichlorides) show complete absence of va - HandI'N - H indicating the dibasic nature of the ligand. TheI'C =N mode is lowered indicating its coordinationwith titanium". The J'C - S, I'N - Nand I'C -- a modesare observed at 1025-1000, 970-920 and 1255-1240respectively indicating complexation t o-: t of theligands. The chelated trichloro derivatives show I'N- Hat 3150. The vTi - S 12 at 330 and Vas and Vs Ti - CIaround 370 and 290 respectively t 3 are the other majorbands in the spectra. The Ti-CI stretching modessuggest an octahedral geometry for the hexa-coordinated Ti with cis CI atoms. In (L), Ti, thepresence of only one I'Ti - N band at 560 againsuggests an octahedral geometry for titanium withtrans azomethine nitrogens.

The diisopropoxy titanium derivatives of schiffbases show bands at 650 and 600 due to Vas and vsTi

(II )

Where X = H, R = CH3 [HyACSBOTC-HzJ

X = CI, R = H [CI Sot SBOTC - Hz]

X = Br R = H [BrSoISB OTC - H2]

1005

INDIAN J. CHEM., VOL. 21A, OCTOBER 1982

- 014 modes of Ti - 0 - Pr group, and this suggests atrigonal-bipyramidal geometry for the complex withthe two isopropoxy groups at cis positions. However,the bis(salicylaldehydato) complex shows two vC = 0frequencies, at 1650 and 1620, which indicatecoordination of only one carbonyl to the metal.

The IR spectra of tin compounds show similarfeatures as their titanium counterparts. The far IRspectra in general show vasSn- C at 590, v.Sn - C at5201 S. vSn- 0 at 470 and vSn- S at 3255. Hence, atrigonal-bipyramidal geometry with cis alkyl groupscan be assigned to the tin complexes.

In the PMR spectra of the schiff bases (in DMSO,chemical shift in b pprn), signals due to-phenolic 0 - H(10.50-13.50), N -H (8.80-8.40) and S-methyleneprotons (4.40-4.50) are observed. The spectrum ofHyAcSBDTC-H2 in benzene shows the signal for S-methylene protons at 4.33, a positive shift of 0.23compared to the position in CDCI3 spectrum (4.56).Methyl protons show signal at 0.57 in the benzenespectrum, a positive shift of 1.76 compared to theposition in CDCI3 (2.33). These benzene induced shiftsmay be caused by a benzene-solute stereospecificinteraction at the electron deficient sulphur andcarbon atoms, and by magnetic anisotropy of benzeneas reported in the case of dialkylthiocarbamatecomplexes 17.

In the trichlorotitanium derivative of BrSaISBDTC-H2, the N - H signal appears at 8.73; all the othertitanium and tin complexes show absence of 0 - H orN - H protons as expected. In these complexes, theazomethine and methylene protons absorb downfieldand upfield respectively as compared to their positions'in the spectra of the ligands. The downfield shifting ofprotons may be due to the donation of the lone pair ofelectrons from nitrogen to the metal while the upfieldshifting of methylene protons may be due to the

1006

electron withdrawing tendency of the thiocarbonylgroup.

The UV spectra of chelated tin dichlorides andorganotin chelates show distinct split bands around390 and 420 nm indicating Iigand-e metal charge-transfer and hence a stable complex formation+!".However, the spectra of titanium compounds ingeneral show only a slight shifting of bands ascompared to their positions in the ligand spectra(around 300, 315, 325 and 360 nrn); this may be due toligand dissociation in the solvent (acetonitrile).

ReferencesI Jensen K A, Z anorg allg Chern, 221 (1934) II.2 Akbar Ali M, Livingstone S E & Phillips D J, Inorg chirn Acta, 7

(1973) 179, 531.3 Akbar Ali M & Bose R, J inorg nucl Chern, 39 (1977) 265.4 Akbar Ali M & Tharafdar T H, J inorg nucl Chern, 39 (1977)

1785.5 Srivastava T N, Chauhan A K S & Agarwal M, Synth react inorg

metal org Chern, 10 (1980) 29.6 Pardhy S A, Gopinathan S & Gopinathan C, Indian J Chern, 19A

(1980) 130.7 Mayer R, Organosulphur chemistry (lnterscience, New York)

1967,219.8 Kovaac J E, Spectrochim Acta, 23A (1967) 183.9 Tandon J P & Prasad R N, J inorg nucl Chern, 37 (1975) 35.

10 Aggarwal R C & Singh S K, Indian J Chern, 7 (1969) 810.II Bellamy L J, The infrared spectra ofcomplex rnolecules(Methuen,

London) 1959, 108.12 Hawthorne S L & Fay R C, J Am chern Soc, 101 (1979) 5268.

13 Coutts R S P & Wailes P C, J organornetal Chern, 50(1973) 145.

14 Mehrotra R C, Rai A K & Singh P R A, Indian J Chern, 1(1980)449.

15 Barbieri R, Cefalu' R, Bosco R, Bonati F & Maggio F, Z anorgallg Chern, 376 (1970) 192.

16 Kulkarni V H, Patil B R & Prabhakar B K, J inorg nucl Chern, 43(1981) 17.

17 Baker K M & Wilson R G, J chern Soc, 13 (1970) 236.18 Barbieri R, Cefalu R, Bosco R, Bonati F & Maggio F, Z anorg

allg Chern, 376 (1970) 180.