The alkylation of (ArHNCH 2 CH 2 ) 2 NH with RX [RX=MeI, (2-C 5 H 4 N)CH 2 Cl] under basic conditions gives (ArHNCH 2 CH 2 ) 2 NMe (Ar=2,6-Me 2 C 6 H 3 L1a, 2,4-Me 2 C 6 H 3 L1b) and (ArHNCH 2 CH 2 ) 2 {(2-C 5 H 4 N)CH 2 }N (Ar=2,4,6-Me 3 C 6 H 2 L2a, 2,4-Me 2 C 6 H 3 L2b) in moderate yield, respectively. Alternatively, L1a and L1b can be accessed by the arylation (with Ar–Br) of (H 2 NCH 2 CH 2 ) 2 NMe in the presence of a catalytic quantity of Pd 2 (dba) 3 . Treatment of L1 with CoCl 2 in n-BuOH gave high-spin [{(ArHNCH 2 CH 2 ) 2 NMe}CoCl 2 ] (Ar=2,6-Me 2 C 6 H 3 1a, 2,4-Me 2 C 6 H 3 1b) in good yield; no reaction occurred with FeCl 2 . The molecular structure of 1a reveals a distorted trigonal bipyramidal geometry with the L1a adopting a mer-configuration. Reaction of L2 with MCl 2 affords the cobalt and iron complexes, [{ArNHCH 2 CH 2 } 2 {(2-C 5 H 4 N)CH 2 }NMCl 2 ] (M=Co, Ar=2,4,6-Me 3 C 6 H 2 2a, 2,4-Me 2 C 6 H 3 2b; M=Fe, Ar=2,4,6-Me 3 C 6 H 2 3a, 2,4-Me 2 C 6 H 3 3b); the octahedral frameworks in 2a and 3a are found to be considerably distorted with one of the two M-N(mesityl-substituted) distances noticeably elongated [M-N 2.597(4)–2.795(2)Å]; no such inequivalence is observed in solution at room temperature. On activation with methylaluminoxane, complexes 1a and 1b display some activity for the oligomerisation of ethylene.