Unquenched orbital angular momentum in quasi-linear two-coordinate transition metal complexes featuring sterically bulky carbazole ligands

Abstract

A series of two-coordinate TM compounds, M(^(tbu)₂carb^(Ph₂CH)₂) (M = Mn, Fe, Co; ^(tbu)₂carb^(Ph₂CH)₂ = 1,8-bis(diphenylmethyl)-3,6-ditertbutylcarbazolide). Each of the complexes displays a bent geometry with a N–M–N bond angle ranging from 140.21(10)° to 144.37(15)°. Despite the non-linear geometry, M(^(tbu)₂carb^(Ph₂CH)₂)₂ (M = Fe, Co) have substantial spin–orbit coupling, and Co(^(tbu)₂carb^(Ph₂CH)₂)₂ displays slow magnetic relaxation with an U_eff value of 30.2 K and a large negative D of −169 cm⁻¹.