IRON(II) ALPHA-AMINO-ACID COMPLEXES FROM NONPROTIC SOLUTIONS - REACTIONS OF [FE(MES)2(PHEN)] WITH ALPHA-AMINO-ACIDS AND THE STRUCTURES OF BIS(L-PROLINATO)(1,10-PHENANTHROLINE)IRON(II) AND BIS(D-PROLINATO)(1,10-PHENANTHROLINE)IRON(II)

The arylation of FeCl2(THF)1.5 in THF with MesMgBr (Mes = 1,3,5-Me3C6H2) in the presence of 9,10-phenanthroline (phen) led to the crystalline [Fe(phen)(Mes)2], 1, which contains a tetrahedral iron(II) sigma-bonded to two aryl groups. They can be removed by a variety of protic ligands under aprotic conditions. The reaction of 1 with amino acids AH led to the isolation of monomeric iron(II)-amino acid complexes [Fe(phen)(A)2] [A = L-prolinato (2), D-prolinato (3), L-phenylalaninato (4), D-phenylalaninato (5), DL-phenylalaninato (6), L-tryptophanato (7), L-Valinato (8)]. They show a diversity in solubility depending on the amino acid residue. All of them have been fully characterized including the X-ray analysis on 2 and 3, which have been shown to be enantiomeric forms. Crystallographic details: 1 is monoclinic, space group I2/a, with a = 13.216(3) angstrom, b = 14.843(3) angstrom, c = 15.904(3) angstrom, alpha = gamma = 90-degrees, beta = 102.32(2)degrees, Z = 4, and R = 0.044. 2 is hexagonal, space group P3(1)21, with a = b = 9.663(2) angstrom, c = 23.743(4) angstrom, alpha = beta = 90-degrees, gamma = 120-degrees, Z = 3, and R = 0.035. 3 is hexagonal, space group P3(2)21, with a = b = 9.692(1) angstrom, c = 23.841(3) angstrom, alpha = beta = 90-degrees, gamma = 120-degrees, Z = 3, and R = 0.053.