Substituted N-picolylethylenediamines of the type (ArNHCH[subscript 2]CH[subscript 2]){(2-C[subscript 5]H[subscript 4]N)CH[subscript 2]}NR [R = Me, 4-CH[subscript 2]=CH(C[subscript 6]H[subscript 4])CH[subscript 2], (2-C[subscript 5]H[subscript 4]N)CH[subscript 2]] and their transition metal(II) halide complexes

Alkylation of (ArNHCH[subscript 2]CH[subscript 2]){(2-C[subscript 5]H[4]N)CH[subscript 2]}NH with RX [RX = MeI, 4-CH[subscript 2]=CH(C[subscript 6]H[subscript 4])CH[subscript 2]Cl) and (2-C[subscript 5]H[subscript 5]N)CH[subscript 2]Cl] in the presence of base has allowed access to the sterically demanding multidentate nitrogen donor ligands, {(2,4,6-Me[subscript 3]C[subscript 6]H[subscript 2])NHCH[subscript 2]CH[subscript 2]}{(2-C[subscript 5]H[subscript 4]N)CH[subscript 2]}NMe (L1), {(2,6-Me[subscript 3]C[subscript 6]H[subscript 3])NHCH[subscript 2]CH[subscript 2]}{(2-C[subscript 5]H[subscript ]4N)CH[subscript 2]}NCH[subscript 2](C[subscript 6]H[subscript 4])-4-CH=CH[subscript 2] (L2) and (ArNHCH[subscript 2]CH[subscript 2]){(2-C[subscript 5]H[subscript 4]N)CH[subscript 2]}[subscript 2]N (Ar = 2,4-Me[subscript 2]C[subscript 6]H[subscript 3] L3a, 2,6-Me[subscript 2]C[subscript 6]H[subscript 3]L3b) in moderate yield. L3 can also be prepared in higher yield by the reaction of (NH[subscript 2]CH[subscript 2]CH[subscript 2]){(2-C[subscript 5]H[subscript 4]N)CH[subscript 2]}[subscript 2]N with the corresponding aryl bromide in the presence of base and a palladium(0) catalyst. Treatment of L1 or L2 with MCl[subscript 2] [MCl[subscript 2] = CoCl[subscript 2]·6H[subscript 2]O or FeCl[subscript 2](THF)[subscript 1.5]] in THF affords the high spin complexes [(L1)MCl[subscript 2]] (M = Co 1a, Fe 1b) and [(L2)MCl[subscript 2]] (M = Co 2a, Fe 2b) in good yield, respectively; the molecular structure of 1a reveals a five-coordinate metal centre with L1 bound in a facial fashion. The six-coordinate complexes, [(L3a)MCl[subscript 2]] (M = Co 3a, Fe 3b, Mn 3c) are accessible on treatment of tripodal L3a with MCl[subscript 2]. In contrast, the reaction with the more sterically encumbered L3b leads to the pseudo-five-coordinate species [(L3b)MCl[subscript 2]] (M = Co 4a, Fe 4b) and, in the case of manganese, dimeric [(L3b)MnCl(µ-Cl)][subscript 2] (4c); in 4a and 4b the aryl-substituted amine arm forms a partial interaction with the metal centre while in 4c the arm is pendant. The single crystal X-ray structures of 1a, 3b·MeCN, 3c·MeCN, 4b·MeCN and 4c are described as are the solution state properties of 3b and 4b.