Magnetic Manipulation and Half-Metal Prediction of One-Dimensional Bimetallic Organic Sandwich Molecular Wires [CpTM₁CpTM₂]_∞ (TM₁ = Ti, Cr, Fe; TM₂ = Sc−Co)

We systematically investigate the stability and electronic and magnetic properties of one-dimensional (1D) bimetallic organic sandwich molecular wires (BOSMWs), [CpTiCpTM] ∞ (TM = Sc−Co, Cp = C 5 H 5 ), [CpCrCpTM] ∞ (TM = V, Mn, Co), and [CpFeCpTM] ∞ (TM = Cr, Co), using ab initio methods. All the BOSMWs are highly stable due to mixed ionic−covalent bonding. With the exceptions of [CpTiCpV] ∞, [CpTiCpMn] ∞, and [CpCrCpV] ∞ exhibiting antiferromagnetic behavior, all the other BOSMWs are ferromagnetic with tunable magnetic moments. In particular, magnetic moments of [CpTiCpCo] ∞ and [CpCrCpMn] ∞ can be as high as 5 μ B per unit cell. Our calculations further show that [CpTiCpTM] ∞ (TM = Cr, Fe), [CpCrCpTM] ∞ (TM = Fe, Co), and [CpFeCpCo] ∞ are robust half-metals (HMs) with large HM gaps. Most importantly, we identify an empirical valence electron filling rule for these BOSMWs, and a BOSMW is found to be a half-metallic ferromagnet whenever N − 5(10) = 5(7) ( N is the sum of the valence electrons of two metal atoms). This electron filling rule, together with the HM equations formulized in this study, can be extended to predict new HM BOSMWs.