Abstract
Complexes of several bivalent metals of the first transition series, and of gold(I), with some S-donor ligands have been synthesised. A series of complexes of thiomalic acid (H0[2]CCH(SH)CH[2]CO[2]H, tmH[3]) and some divalent metals, Ni(tmH[2])[2].2H2O, Fe(tmH) (pyridine), M(tmH). nH2O (M = Mn, Fe or Co) and the salts A[M[II](tm)]. nH2O (A = Li, Na or K and M[II]= Mn, Fe, Co or Ni) has been prepared. The complexes, except of nickel(II), are air-sensitive, and were handled under nitrogen or in vacuo. One nickel(II) complex, Ni(tmH[2])[2].2H2O, has a normal magnetic moment for an octahedral complex while the others show temperature-dependence arising from weak ferromagnetic interactions. All the iron(II)-thiomalates except Fe(tmH)(py), which is antiferromagnetic, also exhibited weak ferromagnetism. The temperature variation of the magnetic moment of Co(tmH). 3H2O was typical for a distorted octahedral monomeric structure, but the remaining cobalt(II) complexes and the manganese(II) complexes also showed antiferromagnetic interaction. Octahedral configurations were assigned to all the transition metal ions from their reflectance spectra, and this, combined with the magnetic data, indicates that all except Ni(tmH[2])[2].2H2O and Co(tmH). 3H2O are polymeric. Mossbauer spectra confirmed the oxidation and spin states and distorted octahedral stereochemistry of the iron(II) complexes. From the infrared investigations it was found that the A[M[II](tm)]. nH2O complexes contain bidentate carboxylate groups and coordinated -S as -SH bands are absent, whereas M(tmH). nH2O (M = Mn or Fe) contain one free carboxylic acid group and one bidentate carboxylate group. In Ni(tmH[2])[2]. 2H2O, unionised, and coordinated, and unionised, and uncoordinated carboxylic acid groups are present. Similar investigations have been carried out with K2[Co(thiop)[2]]. H2O (thiop = thiopropionic acid), Co(cysH)[2]. 2H2O and A [Co(cys)[2]]. 3H2O (A = Li, Na or K) (cysH = cysteine). These complexes contain transition metal ions in distorted octahedral configurations, and are believed to be polymeric. Iron(II) complexes of the Schiff bases NN' -ethylenebis (monothio- acetylacetonimine), (Sacac) 2enH[2], and 2-salicylideneaminobenzenethiol, (H2Sa1ABT) have been prepared. The spin state of Fe[ (Sacac) 2en] has not been established because its magnetic moment (1.7 B.M.) is between the values expected for high-spin and low-spin iron (II). The black complex Fe(SalABT) is antiferromagnetic and is believed to have a six-coordinate structure involving bridging sulphur atoms. A number of new transition metal nitrosyls have been obtained by reaction of the above complexes with nitric oxide. The infrared spectra of the diamagnetic dinitrosyls Fe(tmH) (NO) 2, Co(tm)(NO)[2] and Fe(thiop)(NO)[2]. CH3OH suggest coordinated NO+. The related complex K[Fe(tm) ]NO. 2H2O is paramagnetic with magnetic moments close to the value expected for two unpaired electrons. It is believed that the complex contains S = 3/2 and S = 1/2 spin isomers in equilibrium. A nitrosyl Fe(trp)2NO. 2H2O, obtained by reaction of Fe(trp)[2]. H2O (trp = tryptophan) with nitric oxide, is similar in magnetic behaviour. Some complexes of gold(I) with thiomalic acid have been isolated. These are Au(tnH[2]), Na[2] [Au(tm) ], Ca[Au(tm). 2H2O and Ba[Au(tm)]. H2O. They have polymeric structures involving bridging-sulphur atoms. Reactions between thiomalatogold(I) and sulphur-containing ligands lead to the release of some or all of the coordinated thiomalic acid from thiomalatogold(I). In the reaction of glutathione and cysteine with thiomalatogold(I) polymeric, mixed ligand complexes, i. e. bis (glutathionato)mono(thiomalato) trigold(I) and (cysteinato) -(thiomalato)digold(I), were obtained. In the reaction with sodium diethyldithiocarbamate all the thiomalic acid was released and diethyldithiocarbamatogold(I) was precipitated. Albumin also produced a precipitate with thiomalatogold(I), but the thioether methionine did not.