(FePbII)-Pb-II and Fe-III complexes of macrocyclic compartmental ligands: different cyclization in stepwise template synthesis using Fe-II/Pb-II or Fe-III/Pb-II pairs

The reaction of [bis(3-formyl-5-methylsalicylidene)ethylenediaminato]iron(I I) with diethylenetriamine (dien) in the presence of Pb-II followed by the addition of NaNCS formed a (FePbII)-Pb-II complex, [FePb(L-1)(NCS)(dmf)(ClO 4)] I, where (L-1)(2-) is a dinucleating macrocyclic compartmental ligand d erived from the [2:1:1] condensation of 2,6-diformyl-4-methylphenol, ethyle nediamine and dien, having "salen"- and "saldien"-like metal-binding sites sharing the phenolic entities. The Fe resides in the "salen" site and the P b in the "saldien" site: the Fe ... Pb intermetallic separation is 3.438(2) Angstrom. The Fe assumes a square-pyramidal geometry with an isothiocyanat e nitrogen at the apex. The Pb has a seven-coordinate geometry with a dmf o xygen and a perchlorate oxygen at the axial sites. Complex 1 reacts with mo lecular dioxygen to give a mu-oxo complex [{FePb(L-1)(NCS)(dmf)(ClO4)}(2)(O )]. A similar reaction of chloro[bis(3-formyl-5-methylsalicylidene)ethylene diaminato]iron(III) with dien in the presence of Ph-II formed a mononuclear Fe-III complex [Fe(H2L2)(NCS)][ClO4](2).dmf 2, where H2L2 is a macrocycle derived from the [2:2] condensation of 2,6-diformyl-4-methylphenol and dien . The Fe resides in one "saldien" site and assumes an octahedral geometry w ith an isothiocyanate nitrogen in one apical position. Another metal-bindin g site formed with dien shows unusual condensation; one primary amino group of the dien condenses with one formyl group to form an usual C=N linkage a nd the remaining primary and secondary amino groups of the dien condense wi th another formyl group to form a five-membered imidazoline ring.