Conglomeratic Solid Solutions in trans(N,t-N)-[Co(leucinato)(tren)]I2 and trans(N,t-N)-[Co(norleucinato or norvalinato)(tren)][ClO4]2 [t-N = tertiary amine nitrogen; tren = tris(2-aminoethyl)amine]

Ternary solubility isotherms of trans(N,t-N)-[Co(leu)(tren)]I2, trans(N,t-N)-[Co(n-leu)(tren)][ClO4]2, and trans(N,t-N)-[Co(n-val)(tren)][ClO4]2 [t-N = tertiary amine nitrogen; leu = leucinate(1−), n-leu = norleucinate(1−), n–val = norvalinate(1−), and tren = tris(2-aminoethyl)amine] were determined at 25 °C. Each isotherm consists of two branches of the solubility curve and one eutectic point; the tie lines do not converge to any apex of the pure enantiomers, but diverge widely. These facts mean that the three complexes simultaneously form a conglomerate and a solid solution. X-Ray crystal analyses were carried out for crystals grown from the three racemic aqueous solutions. All of the crystals were isomorphous to each other in spite of having different amino acidates and counter ions. The crystal structures clearly demonstrated the coexistence of D-amino acidate and L-amino acidate at one site of the crystal lattice, that is, a solid solution. Furthermore, all of the crystals were partially optically active: D : L = 63 : 37 for leu complex (space group P32), D : L = 32 : 68 for n-leu one (P31), and D : L = 44 : 56% for n-val one (P31). Head-to-tail hydrogen bonding contacts, which form spiral chains along the c-axis, were commonly found for these complexes.