A new macrocyclic N3S2 ligand and its nickel(II), cobalt(II), rhodium(III)-103, and rhodium(III)-105 complexes
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abstract
The synthesis, structural characterization, and electrochemical properties of N3S2-ligated metal complexes of the ligand 4,10-dithia-1,7,13-triazabicyclo[11.3.3]nonadecane are described. Complexes of Ni(II), Co(II), and Rh(III) have been characterized by X-ray crystallography as six-coordinate complexes of the pentadentate ligand with Cl- anions occupying the position trans to the secondary amine donor. In addition, the chelation of the N3S2 donor ligand to the reactor-produced radionuclide 105Rh was shown to give a single product in high yield (>98% at pH 5). The ligand is prepared by the template reaction of (N,N'- bis(2-mercaptoethyl)-1,5-diazacyclooctane)nickel(II), Ni-1, with bis(2-chloroethyl)amine, yielding (S,S'-(3-aza-1,5-pentanediyl)- N,N'-bis(2-mercaptoethyl)-1,5-diazacyclooctane- N,N',N'',S,S')nickel(II) chloride, [Ni(amine)Cl]Cl. Removal of nickel from [Ni(amine)Cl]Cl and subsequent reaction of the ligand with CoCl2 or RhCl3xH2O afforded (S,S'-(3-aza-1,5- pentanediyl)-N,N'-bis(2-mercaptoethyl)-1,5-diazacyclooctane- N,N',N'',S,S')cobalt(II) chloride, [Co(amine)Cl]Cl, C14H29N3S2CoCl21.75MeOH, and (S,S'-(3-aza-1,5- pentanediyl)-N,N'-bis(2-mercaptoethyl)-1,5-diazacyclooctane- N,N',N'',S,S')rhodium(III) chloride, [Rh(amine)Cl]Cl2, C14H29N3S2RhCl3, respectively. The blue complex [Ni(amine)Cl]Cl, C14H29N3S2NiCl2MeOH, contains nickel in an octahedral environment of N3S2Cl donors and crystallizes in the monoclinic space group P2(l)/(c) with a = 13.278(3) , b = 11.976(4) , c = 12.928(4) , = 102.17(2), and Z = 4. The complex [Co(amine)Cl]Cl is fuchsia and crystallizes in the monoclinic space group P2(l)/(c) with a = 10.321(2) , b = 7.892(1) , c = 27.684(3) , = 96.91(1), and Z = 4. Yellow crystals of [Rh(amine)Cl]Cl2, C14H29N3S2RhCl3, were determined to be in the monoclinic space group C1c1 with a = 9.655(2) , b = 16.805(4) , c = 11.756(3) , = 96.29(2), and Z = 4.
