Mixed-valence complexes of the type [ C O ~~( ~-S O , ) , ( ~-L ) ~C O ~~~~( H ~O ) , ( ROH),,,] ( n = 0 , l I or 2; R = M e or Prn) have been prepared and characterized, where the deprotonated Schiff-base ligands Lz-are either symmetrical, such as N,N'-ethylenebis(salicy1ideneiminate) (salen), N,N'-ethylenebis(a-methylsalicylideneiminate) (a,#'-Me,-salen), propane-l,3-diylbis(salicylideneiminate) (salpd), and propane-l,3-diylbis(a-methylsalicylideneiminate) (a,a'-Me,-salpd), or unsymmetrical such as propane-l,3-diyl(a-methylsalicylideneiminate) (salicylideneiminate) ( a -Me-salpd). An X-ray structure determination of [Coil (p-S03)2(~-a,a'-Me2-salpd)2C~1112( PrnOH)2]. 2PrnOH showed the presence of bridging phenolic oxygens and sulphite ions. The mixed-valence state Coil' (S = 0)-Coil (S = ;)-Coili (S = 0) in these trinuclear complexes has been demonstrated by cryomagnetic measurements because the effective magnetic moments (4.40-5.00) at room temperature correspond to the monomeric complex of a cobalt(ii) ion in a high-spin state. Down to 77 K, no spinexchange interaction was observed between the cobalt( 111) and cobalt(it) ions. 1.r. spectra and thermal gravimetric-differential thermal analysis data have been obtained and discussed with regard to the co-ordination modes of the solvent molecules water, methanol, ethanol, and propan-1 -01.Many studies have been reported on the preparation and magnetic properties of polynuclear complexes of transition metals, especially in relation to the phenomenon of superexchange interaction.'-' There are two classes of trinuclear cobalt complexes of mixed-spin states; one includes mixedvalence trinuclear complexes of the form Co"' (S = O)-col' ( S = $)-€o"' (S = 0)l3 and another, mixed-spin trinuclear complexes of the form Co" (S = $)-€o" (S = &Co" (S =
