Uniform sidearm derivatisations in a tetrapodal pentaamine: Ligands with NN4O4 donor sets, and a bis(ferrocenecarbaldehyde aminal)

The tetrapodal pentaamine 2,6-C5H3N[CMe(CH2NH2)(2)](2) (pyN(4), I) readily reacts with four equivalents of 2-hydroxyphenyl-substituted carbonyl compou nds, such as (i) 2-hydroxybenzaldehyde, (ii) 2,4-dihydroxybenzaldehyde, (ii i) 3,5-di-tert-butyl-2-hydroxybenzaldehyde, and (iv) 2-hydroxyacetophenone, to give the corresponding Schiff base derivatives with NN4O4 donor sets (i : 2; ii: 3, iii: 4; iv: 5). With Ligand 5, two transition metal complexes ( M = Ni-II (6), Cu-II (7)) have been isolated, which are dinuclear and conta in square-planar M(N2O2) units, linked by a pyridine-derived spacer whose n itrogen atom is uncoordinated. The reaction of 1 with ferrocenecarbaldehyde affords, under neutral conditions and irrespective of an excess of the ald ehyde present, the bis(aminal) 8 as the major product, in which the two 1,3 -propylenediamine subunits of I have condensed with two carbaldehyde moieti es to give two 1,3-diazacyclohexane rings. All compounds have been characte rised by IR spectroscopy and elemental analysis, as well as H-1 and C-13 NM R spectroscopy (except paramagnetic 7). The crystal structures of compounds 2, 6, 7, and 8 have been determined.