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The reactions of niobium and tantalum pentaethoxides withtrans-cinnamic acid (HCA) and dihydrocinnamic acid (HDCA) were carried out in different stoichiometric ratios. The complexes of the type M(OEt)5−n(CA)n and M(OEt)5−n(DCA)n, (n=1, 2 or 3 and M=Nb or Ta) were obtained.

The synthesis and characterization of the complexes from the reactions of trichloro(cyclopentadienyl)titanium(IV) with 1,5-diarylthiocarbazones (aryl=phenyl,o-tolyl,o-chlorophenyl,p-tolyl,p-chlorophenyl, or 3,5-dimethylphenyl) are reported. They are of the types CpTi(HDz)Cl2 and CpTi(HDz)2Cl (Cp=cyclopentadienyl, HDz−=the mono-anion of a 1,5-diarylthiocarbazone, H2Dz). The compounds are nonelectrolytes in dimethylformamide (DMF). In solid state, the far i.r. spectra of CpTi(HDz)Cl2 indicate the complexes to be dimeric, involving Cl-bridges.

Niobium(V) and tantalum(V) pentaethoxides react with monofunctional benzoyl hydrazones (BHy) in refluxing benzene to give products of the type, M(OEt)5−n(BHy)n (where M=Nb or Ta and n=1, 2 or 3). The complexes have been characterised on the basis of elemental analysis, spectral (i.r. and n.m.r.) and molecular weight data.

Dichlorobis(cyclopentadienyl)titanium(IV), Cp2TiCI2, reacts with bidentate Schiff bases such as salicylideneaniline, salicylidene-o-toluidine, salicylidene-m-toluidine, salicylidene-p-toluidine and 2-hydroxy-l-naphthyl

Oximate complexes of bis(cyclopentadienyl)zirconium(IV) chloride (Cp2ZrCl2 ) having the general formulae Cp2Zr(Ox), Cp2Zr(OxH)Cl and Cp2Zr(OxH)2 [where OxH2 = RC6H4C(OH)R′: NOH, R = H, Me, R′= H, Me, Et, n-Pr; PhC: N(OH)CH(OH)Ph and R″C : N(OH)N(OH): CR″, R″ = H, Me and Ph] have been synthesized by reacting bis(cyclopentadienyl)zirconium(IV) chloride with the appropriate oxime in tetrahydrofuran in the presence of triethylamine at room temperature. The complexes have been characterized by their elemental analysis, i.r. and electronic spectra, molecular weight determination, electrical conductance and magnetic measurements.

Reactions of niobium and tantalum pentaethoxides with ethyl-1-hydroxycyclohexylacetate (HECA), ethyl 2-hydroxy-2-arylpropionate (HEAP) and ethyl 2-hydroxy-2-aryl butyrate (HEAB) lead to compounds of the type [M(OEt)5−n(L)n] (where M=Nb or Ta; n=1, 2 or 3; and L=HECA, HEAP or HEAB). These were characterised by elemental analysis, molecular weight determinations and i.r. and n.m.r. spectral studies. Alcoholysis reactions witht-butanol were also carried out.

Reactions of titanium(IV) isopropoxide with ethyl 1-hydroxycyclohexylacetate, ethyl 2-hydroxy-2-arylpropionate, ethyl 2-hydroxy-2-arylbutyrate and ethyl 2-hydroxy-2-arylhydrocinnamate have been studied in dry benzene in different molar ratios under strictly anhydrous conditions. The Ti(OPr-i)4-nLn type compounds, where L = hydroxy ester and n = 1 to 4, have been isolated and characterised by elemental analysis, molecular weight, i.r. and n.m.r. spectral studies. These products may be distilled unchanged under reduced pressure.

Uranyl(VI) complexes of malonic acid dihydrazide (MDH2) and phthalic acid dihydrazide (PDH2) and the products of their reactions with four β-diketones have been characterised by elemental analysis and by electrical conductance, and spectral (i.r. and electronic) measurements. The MDH2 and PDH2 complexes UO2(L)2(H2O)2 are eight coordinate whereas the macrocyclic UO2(L′)(H2O)2 complexes are six coordinate. In each complex MDH2 and PDH2 act as bidentate liglands having the coordination sites at secondary amide-nitrogen atoms.

The reactions of tetra(isopropoxy)hafniumiso-propanol, Hf(OPri)4 · PriOH with monofunctional bidentate (MH) and bifunctional tridentate (BH2) benzoyl hydrazones (derived from the condensation of benzoyl hydrazine with aldehydes/ ketones) in different molar ratios have been carried out in refluxing benzene. Products of the type, Hf(OPri)4−n(M)n and Hf(OPri)4−2n(B)n (where n=1 to 4) were obtained and characterized on the basis of elemental analyses, electrical conductance measurements, and spectral (infrared, electronic and1H n.m.r.) data.

The synthesis and characterization of the complexes from the reactions of mono(cyclopentadienyl)titanium(IV) chloride (CpTiCl3) with Schiff bases. (obtained by the condensation of aldehyde/ketone withS-methyldithiocarbazate, ) are reported. They are of the type: CpTiCl2(SB). CpTiCl(SB)2 and CpTiCl(SB′) (where [SB]− and [SB′]2− are the anions of the monobasic (SBH) and dibasic (SB′H2) Schiff bases, respectively). The compounds are nonelectrolytes in dimethylformamide. The presence of the cyclopentadienyl group was confirmed from infrared and proton magnetic resonance spectra.

Dichlorobis(methylcyclopentadienyl)titanium(IV) reacts with 1,5-diarylthiocarbazones (aryl=phenyl,p-tolyl,o-chlorophenyl orp-chlorophenyl) in 1∶1 and 1∶2 molar ratios in tetrahydrofuran in the presence of triethylamine, to yield [(MeCp)2Ti(HDz)Cl], [(MeCp)2Ti(Dz)] and [(MeCp)2-Ti(HDz)2] (MeCp=methylcyclopentadienyl; HDz− and Dz2− are the mono- and di-anions of a 1,5-diarylthiocarbazone, H2Dz).S-Methyl-1,5-diphenylthiocarbazone and [(MeCp)2TiCl2] react to give [(MeCp)2Ti(MeDz)Cl] and [(MeCp)2Ti(MeDz)2] (MeDz− represents the mono-anion ofS-methyl-1,5-diphenylthiocarbazone, HMeDz) in an excess of triethylamine. These new derivatives have been characterised on the basis of elemental analyses, magnetic moment, electrical conductance, i.r.,1H n.m.r. and electronic spectral studies.

A series of hafnium(IV) complexes has been synthesised by the reaction of hafnium(IV) isopropoxide-isopropanol(1/1) with 2-aminocyclopent-1-ene-1-dithiocarboxylic acids RNHC(CH2)3CC(S)SH, (where R=H, Me, Et or Bu) in 1∶1 and 1 ∶ 2 molar ratios. The compounds have been characterized by elemental analysis, i.r. and1H n.m.r. spectral studies. The complexes polymerise slowly in solution, probablyvia the sulphur atom of the >C=S group.

The chemistry of bidentate (S,S−) donor ligands 2-amino-1-cyclopentene-1-dithiocarboxylic acid (HL) and itsN-alkyl derivatives [alkyl = Me (HL1), Et(HL2) and Bu(HL3)] with hafnium(IV) chloride in 1∶1, 1∶2, 1∶2, 1∶3 and 1∶4 molar ratios is described. These complexes were characterized by elemental analysis, u.V., i.r. and n.m.r. spectral studies. Disulphur chelation with coordination numbers 5, 6, 7 and 8 was observed in all the metal chelates.

Hafnium(IV) complexes have been prepared by the reactions of hafnium(IV) isopropoxide isopropanol with Schiff bases [bis(salicylaldehyde)hydrazine] (Sal-AH2), (bis(o-hydroxyacetophenone)hydrazine] (Acp-AH2), [bis(resacetophenone)hydrazine] (Res-AH2), [bis(salicylaldehyde)ethylenediimine) (SaleneH2), [bis(o-hydroxyacetophenone)ethylenediimine] (AcpeneH2) and [bis(salicylaldehyde)o-phenylenediimine] (SalpheneH2) (derived from salicylaldehyde,o-hydroxyacetophenone, resacetophenone and diamines) in appropriate molar ratios using benzene as solvent. The complexes [Hf(OPr-i)2(SB)] and [Hf(SB)2] (where SB2− represents the dianion of the Schiff base) are reported. The complexes of Sal-A, Acp-A and Res-A are 5-and 6-coordinate while those of salene, acpene and salphene are 6-and 8-coordinate. The Schiff bases draw on Sal-A, Acp-A and Res-A are tridentate and salene, acpene and salphene are tetradentate. The mode of bonding through nitrogen and oxygen and the stereochemistry of the complexes are discussed in relation to the elemental analyses and spectra (electronic, infrared and nuclear magnetic resonance).

The ligating properties of 2-iminocyclohexanedithiocarboxylic acid were investigated. Complexes with halides of manganese(II), iron(II), cobalt(II), nickel(II), copper(II), zinc(II), cadmium(II) and mercury(II) were synthesized and characterized by elemental analysis, magnetic measurements, electron and i.r.1H n.m.r. spectral studies. The results are concordant with a bidentate coordination of the—CS2 group to the metal ions.

Five new MCl3 · TEP compounds, where M = Ce, Pr, Nd and Sm, and LaCl3 2 TEP have been prepared. The magnetic susceptibility and i.r. spectra of these complexes are discussed.