Alkylation of (ArNHCH2CH2){(2-C5H4N)CH2}NH with RX [RX = MeI, 4-CH2
CH(C6H4)CH2Cl) and (2-C5H5N)CH2Cl] in the presence of base has allowed access to the sterically demanding multidentate nitrogen donor ligands, {(2,4,6-Me3C6H2)NHCH2CH2}{(2-C5H4N)CH2}NMe (L1), {(2,6-Me3C6H3)NHCH2CH2}{(2-C5H4N)CH2}NCH2(C6H4)-4-CH
CH2
(L2) and (ArNHCH2CH2){(2-C5H4N)CH2}2N (Ar = 2,4-Me2C6H3L3a, 2,6-Me2C6H3L3b) in moderate yield. L3 can also be prepared in higher yield by the reaction of (NH2CH2CH2){(2-C5H4N)CH2}2N with the corresponding aryl bromide in the presence of base and a palladium(0) catalyst. Treatment of L1 or L2 with MCl2
[MCl2
= CoCl2·6H2O or FeCl2(THF)1.5] in THF affords the high spin complexes [(L1)MCl2]
(M = Co 1a, Fe 1b) and [(L2)MCl2]
(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)MCl2]
(M = Co 3a, Fe 3b, Mn 3c) are accessible on treatment of tripodal L3a with MCl2. In contrast, the reaction with the more sterically encumbered L3b leads to the pseudo-five-coordinate species [(L3b)MCl2]
(M = Co 4a, Fe 4b) and, in the case of manganese, dimeric [(L3b)MnCl(µ-Cl)]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.