π-Donor BETS Based Bifunctional Superconductor with Polymeric Dicyanamidomanganate(II) Anion Layer: κ-(BETS)2Mn[N(CN)2]3

π-Donor BETS Based Bifunctional Superconductor with Polymeric Dicyanamidomanganate(II) Anion Layer: κ-(BETS)2Mn[N(CN)2]3