S.E. Livingstone

Metal chelates of dithiocarbazic acid and its derivatives. IX. Metal chelates of ten new schiff bases derived from S-methyldithiocarbazate

The Schiff bases RR′CNNHC(S)SCH3 derived from S-methyldithiocarbazate have been prepared. The mass spectra of the Schiff bases having R = Me and R′ = Ph, 2-furyl, and 2-thienyl and R = R′ = Ph are similar and display strong peaks for the molecular ion M and the ions MCH3S, MCH3SH, R′CNH, R′CN, R′H, R′, and R′H. A mechanism of fragmentation is proposed. Complexes of the Schiff bases of the type Met(RR′CNNCSSCH3)2 (MetNi, Cu, Zn, Pd, and Pt) have been isolated in most instances. When R′ = Bun or Bui, nickel ion catalyses the hydrolysis of the Schiff base with the concomitant formation of the S-methyldithiocarbazate complex [Ni(H2NNHCSSCH3)3](NO3)2. The metal complexes are being tested for anti-cancer activity.

Metal chelates of dithiocarbazic acid and its derivatives. VI. Antiferromagnetic and ferromagnetic interactions in some copper(II) complexes of salicylaldehyde and acetylacetone Schiff bases derived from s-methyldithiocarbazate

Abstract The Schiff base S-methyl-β-N-(2-hydroxyphenyl)methylendithiocarbazate, o -HO.C 6 H 4 CHNNHC(S)SCH 3 , and the corresponding 5chloro, 5-bromo, 5-nitro, and 3-methoxy derivatives were prepared from the appropriate salicylaldehyde and S-methyldithiocarbazate. The acetylacetone Schiff base 2-hydroxy-4-methyl-5,6-diaza-7-thiono-8-thianona-2,4-diene, CH 3 C(OH)CHC(CH 3 )NNHC(S)SCH 3 , was also prepared. By the loss of two protons the ligands behave as doubly negatively charged ONS tridentates. Complexes of the type M(ONS).B (M = Cu,Ni; B = py, H 2 O) and Co III (ONS)(ONSH) were isolated. In addition, the complexes M(ONS) (M = Cu, Ni, Pd, Pt) were obtained. It is suggested that where M = Ni, Pd, Pt, the complexes possess square-planar, dimeric thiolo-bridged structures. The copper complexes Cu(ONS) of the 5-chloro,5-bromo-, and 3-methoxy- salicylaldehyde Schiff bases are red and have anomalously low moments which decrease with decrease in temperature. This behaviour is attributed to antiferromagnetic interaction due to an oxygen-bridged dimeric structure. The moment of the green copper complex of the 5-nitro-salicylaldehyde Schiff base increases with decrease in temperature, indicating ferromagnetic interaction between the copper atoms. The value of the moment at 83′K is 2.43 B.M. and the magnetic data fit the expression for a tetrahedral cluster of four ferromagnetically interacting copper atoms. The green copper complex of the acetylacetone Schiff base is also ferromagnetic.

Metal chelates of dithiocarbazic acid and its derivaties. I. Complexes of dithiocarbazic acid and its S-methyl ester

Abstract The complexes CR(H 2 NNHCS 2 ) 3 . 2H 2 O, Ni(H 2 NNHCS 2 ) 2 . H 2 O, and M(H 2 NNHCS 2 ) 2 (M = Pd, Pt, Zn, Cd, Pb) have been obtained by the reaction of hydrazinium dithiocarbazate with the appropriate metal salt. Infrared and electronic spectral data indicate that the ligand is coordinated via one nitrogen and one sulphur atom. S -Methyldithiocarbazate yields high-spin nickel(II) complexes of two types: [Ni(H 2 NNHCSSCH 3 ) 3 ]X 2 (X = NO 3 , Cl, Br) and Ni(H 2 NNHCSSCH 3 ) 2 X 2 (X = Cl, NCS). Spectral data indicate NS coordination in these compounds. The complexes M(H 2 NN=CSSCH 3 ) 2 (M = Ni, Pd, Pt) containing deprotonated S -methyldithiocarbazate were also isolated; the nickel complex is diamagnetic.

Metal chelates of dithiocarbazic acid and its derivatives. II. Complexes of the schiff bases formed by condensation of S-methyldithiocarbazate with acetone and pyridine-2-aldehyde

Abstract The acetone Schiff base S-methyl-N-isopropylidendithiocarbazate, Me2CNNC(SMe)SH (NSH), forms the stable, crystalline complexes [M(NS)2] (M=Co, Ni, Pd, Pt, Cu), which are non-electrolytes in nitrobenzene. The nickel, palladium, platinum, and copper complexes are square-planar but magnetic and spectral evidence indicates that the cobalt complex is tetrahedral. The pyridine-2-aldehyde Schiff base S-methyl-N-(2-pyridyl)methylendithiocarbazate, C5H4NCHNNC(SMe)SH (N-N-SH), forms the square-planar 1:1 complexes [M(NNS)X] (M = Ni, Pd, Pt, Cu; X = Cl, Br, I, NCS, or NO3) and [Cu(NNS)H2OClO4 and the octahedral 2:1 complexes [M(NNS)2] (M = Fe, Ni). The manganese(III) complex [Mn(NNS)Cl2]. 1 2 H2O is probably octahedral and polymeric. With iron(III) the complexes [Fe(NNS)2ClO4 and [Fe(NNS)2][FeCl4] were obtained. Both the iron(II) complex and the iron(III) complex cation are spin-paired. Bivalent cobalt is oxidized to yield the cobalt(III) complexes ion [Co(NNS)2], which was isolated as [Co(NNS)2]NO3 H2O and [Co(NNS)2[CoX4] (X = Cl, Br, NCS).

Metal chelates of dithiocarbazic acid and its derivatives. III. Complexes of the tridentate schiff base α-N-Methyl-S-methyl-β-N-(2-pyridyl)methylendithiocarbazate with some 3d metal ions

Abstract The Schiff base, α- N -methyl- S -methyl-β- N -(2-pyridyl)methylendithiocarbazate, C 5 H 4 NCHNN(Me)C(SMe)S (NNMeS), behaves as a neutral tridentate ligand, forming stable crystalline complexes with first-row transition metal ions. It forms the monoligand complexes Cr(NNMeS)Cl 3 , Mn(NNMeS)X 2 (X = Cl, NCs), M(NNMeS)X 2 (M = Ni, Cu; X = Cl, Br, I, NCS), and [Cu(NNMeS)(H 2 O)]SO 4 . The manganese and nickel complexes are probably halogen-bridged, octahedral, and polymeric. The structures of the copper complexes are uncertain The bis-ligand complexes, which were isolated, are [M(NNMeS) 2 ](ClO 4 ) 2 (M = Fe, Co, Ni), [Ni(NNmeS) 2 ](BF 4 ) 2 2H 2 O, [M(NNMeS) 2 ][MX 4 ] (M = Fe, Co; X = Cl, Br, I, NCS), and [Fe(NNMeS) 2 ][FeCl 4 ] 2 . In these complexes the iron(II) cation is low-spin and diamagnetic but the cobalt(II) cation is high-spin.

Metal chelates of dithiocarbazic acid and its derivatives. VII. The magnetism of some copper(II) complexes of salicylaldehyde Schiff bases derived from N-methyl-S-methyldithiocarbazate and S,S′-dimethyldithiocarbazate

Abstract The Schiff bases α- N -methyl-{S}-methyl-β- N -(2-hydroxyphenyl)methylendithiocarbazate o-HO.C 6 H 4 .CH = NNMeC(=S)SMe (HONMeS), its 3-methoxy derivative (3-MeOHONMeS), 1-(2-hydroxyphenyl)-2,3-diaza-4-methylthio-5-thiahexa-1,3-diene, o-HO.C 6 H 4 .CH = NNC(SMe) 2 (HONSMe) and its 5-chloro and 5-bromo derivatives (5XHONSMe; X = Cl, Br) were prepared. By the loss of a proton the Schiff bases act as uni-negatively charged ONS tridentate ligands. The complexes Ni(ONMeS)X (X = Cl, Br, NCS) are diamagnetic and square-planar, while the complex Ni(ONMeS) 2 is paramagnetic and octahedral. The palladium complex Pd(ONSMe)Cl was also isolated. the copper complexes Cu(ONMeS)NO 3 , Cu(ONSMe)NO 3 , and [Cu(ONMeS)py]ClO 4 display normal magnetic behaviour. The compound Cu(ONMeS)BF 4 has an anomalously low moment (0.88 B.M.) at room temperature and the moment decrease to 0.38 B.M. at 93°K due to antiferromagnetic interaction. The compound Cu 2 (3MeOONMeS)Cl 3 also displays antiferromagnetic interaction between the two copper atoms of the dimer. The complexes Cu 3 (ONMeS) 2 Cl 4 and Cu 3 (ONSMe) 2 Cl 4 most likely have a linear trimeric structure; the magnetic data for the latter compound fit an equation for a linear trimer with three antiferromagnetically interacting copper atoms. The compounds Cu(5ClONSMe)Cl and Cu(5BrONSMe)Cl are monomeric with normal magnetic moments.

Metal chelates of α-diimines containing a benzothiazole moiety. III. Infrared, thermogravimetric, and magnetic investigations of some sulphate complexes

Some metal sulphate complexes of the α-diimine ligands, 2-(2-pyridyl)benzothiazole (pbt) and 2-(6-methyl-2-pyridyl)benzothiazole (mpbt)are reported. Their infrared spectra indicate that the complexes can be divided into three types: (i) the complexes [Co pbt(H2O)4]SO4, [Ni pbt(H2O)4]SO4.12H2O, [Cd pbt(H2O)2]SO4, and [Cd mpbt(H2O)2]SO4 which contain ionic sulphate; (ii) the complex [Pd pbt SO4(H2O)] in which the sulphato group behaves as a unidentate ligand; (iii) the complexes Pd mpbt So4, Ni pbt SO4, Cu pbt(H2O)2SO4, Cu pbt py2SO4, and Cu mpbt(H2O)2SO4, which contain bridging sulphato groups. The magnetic moments of Cu pbt(H2O)2SO4 and Cu mpbt(H2O)2SO4 are constant over the temperature range 300–80° K, indicating the absence of any anti-ferromagnetic interaction in these compounds.

Metal chelates of α-diimines containing a benzothiazole moiety. I. Complexes of 2-(2-pyridyl)benzothiazole

Abstract 2-(2-pyridyl)benzothiazole (pbt) acts as a bidentate ligand, coordinating through both nitrogen atoms. Cobalt(II) forms the tetrahedral complexes CoX 2 (pbt) (X = Cl, Br) and the high-spin octahedral complexes CoX 2 (pbt) 2 (X = Cl, Br, I) and [Co(pbt)(H 2 O) 4 ]SO 4 Nickel(II) forms mono-, bis-, and tris-ligand complexes. The tris complex [Ni(pbt) 3 ](ClO 4 ) 2 and the bis complexes NiX 2 (pbt) 2 (X = Cl, Br, SCN, NO 3 ) are octahedral with moments in the range 3.1–3.3 B.M. The mono complexes NiCl 2 (pbt) and Ni(CH 3 CO 2 ) 2 (pbt)(H 2 )) 2 have moments in the range 3.3–3.6 B.M.; the spectrum of NiCl 2 (pbt) indicates that the complex is tetragonal and polymeric with chloro bridges. The mono complex [Ni(pbt)(H 2 O) 4 SO 4 was also isolated. With palladium(II) and platinum(II) the mono complexes MX 2 (pbt) (M = Pd, X = Cl, Br, SCN, NO 2 ; M = Pt, X = Cl, Br, SCN) and one bis complex PtI 2 (pbt) 2 were obtained. The copper(II) complex Cu(pbt) 2 (ClO 4 ) 2 . H 2 O has one perchlorate group coordinated in the solid state and in nitrobenzene solution. The spectra of the mono complexes CuX 2 (pbt) (X = Cl, Br, SCN, NO 3 ) indicate five- or six-coordination. The thiocyanato complex contains a bridging SCN group. The insoluble copper(I) complex CuI(pbt) is probably dimeric with iodo bridges. Mono complexes MX 2 (pbt) (M = Zn, X = Br, I; M = Cd, X = Cl, Br, I, SCN) and bis complexes Zn(SCN) 2 (pbt) 2 and CdI 2 (pbt) 2 were isolated. The spectra of Zn(pbt) 2 (ClO 4 ) 2 .H 2 O and Cd(pbt) 2 (ClO 4 ) 2 indicate perchlorate coordination.

Metal chelates of dithiocarbazic acid and its derivatives. V. complees of the NNS ligand 2-(2,3-diaza-4-methylthio-5-thiahexa-1,3-dienyl) pyridine with 3d metal ions

Abstract The Schiff base, 2-(2,3-diaza-4-methylthio-5-thiahexa-1,3-dienyl) pyridine, C 5 H 4 NCHNNC(SMe) 2 (NNSMe), forms stable, crystalline complexes with manganese(II), cobalt(II), nickel(II), and copper(II) The complex Mn(NNSMe)Cl 2 is probably halogenbridged and six-coordinate. With cobalt the complexes Co(NNSMe)X 2 (X = Cl, Br, I), Co(NNSMe) 2 (NCS) 2 H 2 O, [Co(NNSMe) 2 NO 3 ]NO 3 , [Co(NNSMe) 2 ](ClO 4 ) 2 H 2 O and [Co(NNSMe) 2 ](BF 4 ) 2 were isolated. The halide complexes are tetrahedral, with bidentate NN-bonded ligand. The nitrato complex is probably five-cordinate, with NN-bonded ligand. The perchlorate and fluoborate complexes are lowspin. All nickel complexes isolated are six-coordinate. The complex [Ni(NNSMe) 2 NO 3 ]NO 3 probably has bidentate ligand and one bidentate nitrate. The other nickel complexes Ni(NNSMe)X 2 (X = Cl, Br, I, NCS) and [Ni(NNSMe) 2 ](ClO 4 ) 2 contain tridentate NNS bonded ligand, and the mono-ligand complexes are anion-bridges. Thi structure of Cu 2 (NNSMe)Cl 4 is uncertain. The complexes Cu(NNSMe)X 2 (X = NO 3 , NCS) have coordinated anion. Bidentate NN-bonded ligand is present in the thiocyanato complex. The complexes [Cu(NNSMe) 2 ](ClO 4 ) 2 4H 2 O, [Cu(NNSMe) 2 ](BF 4 ) 2 and [Cu(NNSMe) 2 I]BF 4 contain bidentate NN-bonded ligand and resemble the complexes of diimine ligands such as 1,10-phenanthroline. The reasons for the predominantly bidentate behavior of NNSMe with cobalt(II) and copper(II), and tridentate behaviour with nickel(II) are discussed.

Metal chelates of dithiocabazic acid and its derivatives. IV. Complexes of the tridentate schiff base α-N-Methyl-S-methyl-β-N-(6-methylpyrid-2-yl)methylendithiocarbazate

Abstract The Schiff base α-N-methyl-S-methyl-β-N-(6-methylpyrid-2-yl)methylendithiocarbazate, 6-MeC5H3NCHNN(Me)C(SMe)S(MeNNMeS), acts as a tridentate ligand and forms stable, crystalline complexes with iron(II), cobalt(II), nickel(II), and copper(II). The bis-ligand complexes [M(MeNNMeS)2](ClO)4)2.nH2O(M = Fe, Co, Ni), [Co(MeNNMeS)2](BF4)2, [Fe(MeNNMES)2][FeI4], [Fe(MeNNMeS)2][FeIIICl4]2, and [Co(MeNNMeS)2][CoX4] (X = C, Br, NCS) were isolated. The iron(II) cation [Fe(MeNNMeS)2]2+ is low-spin. The mono-ligand complexes M(MeNNMeS)(NCS)2 (M = Fe, Ni) are six-coordinate and probably polymeric with thiocyanato bridges. On the other hand, spectral evidence indicated that the halogeno-complexes M(MeNNMeS)X2 (M = Fe, Ni, Cu; X = Cl, Br) are five-coordinate probably with a distorted trigonal bipyramidal structure.