TY - JOUR
T1 - Metal ion binding by amino acids. Preparation and crystal structures of two calcium L‐asparatate hydrates
AU - Schmidbaur, Hubert
AU - Bach, Ina
AU - Wilkinson, Dallas L.
AU - Müller, Gerhard
PY - 1989/8
Y1 - 1989/8
N2 - Crystalline calcium(II) L‐aspartate dihydrate, Ca(LAsp) · 2H2O (2), has been obtained in a three‐step procedure from CaCO3 and L‐aspartic acid L‐AspH2 via calcium bis(L‐hydrogenaspartate) Ca(L‐AspH)2 and calcium hydrogen L‐aspartate chloride dihydrate Ca(L‐AspH)Cl · 2H2O. The crystals of 2 are orthorhombic, space group P212121. The structure is a coordination polymer with the metal atoms arranged in double chains interconnected by aspartate dianions. Each Asp2− ligand is coordinated to the metal ion as a N,Oα,Oβ tripod. In addition, two water molecules and three β‐carboxylate oxygen atoms from neighbouring units are also coordinated to each metal atom, giving a coordination number of eight for each calcium. The β‐carboxylate oxygen atoms form also a bridge between metals of a parallel chain of metal atoms. – A crystalline tetrahydrate (monoclinic, space group C2) Ca(L‐Asp) · 4H2O (1) has been prepared from L‐AspH2 and Ca(OH)2. The structure contains two molecules in the asymmetric unit. Each calcium atom is seven‐coordinate and surrounded by an N,Oα‐chelating L‐Asp2− ligand, four water molecules, and one oxygen atom of the β‐carboxylate group of a neighbouring molecule. Due to this interaction, the monomeric units are linked to give a one‐dimensional coordination polymer chain. – In both structures the double stands and chains, respectively, are crosslinked by a network of hydrogen bonds.
AB - Crystalline calcium(II) L‐aspartate dihydrate, Ca(LAsp) · 2H2O (2), has been obtained in a three‐step procedure from CaCO3 and L‐aspartic acid L‐AspH2 via calcium bis(L‐hydrogenaspartate) Ca(L‐AspH)2 and calcium hydrogen L‐aspartate chloride dihydrate Ca(L‐AspH)Cl · 2H2O. The crystals of 2 are orthorhombic, space group P212121. The structure is a coordination polymer with the metal atoms arranged in double chains interconnected by aspartate dianions. Each Asp2− ligand is coordinated to the metal ion as a N,Oα,Oβ tripod. In addition, two water molecules and three β‐carboxylate oxygen atoms from neighbouring units are also coordinated to each metal atom, giving a coordination number of eight for each calcium. The β‐carboxylate oxygen atoms form also a bridge between metals of a parallel chain of metal atoms. – A crystalline tetrahydrate (monoclinic, space group C2) Ca(L‐Asp) · 4H2O (1) has been prepared from L‐AspH2 and Ca(OH)2. The structure contains two molecules in the asymmetric unit. Each calcium atom is seven‐coordinate and surrounded by an N,Oα‐chelating L‐Asp2− ligand, four water molecules, and one oxygen atom of the β‐carboxylate group of a neighbouring molecule. Due to this interaction, the monomeric units are linked to give a one‐dimensional coordination polymer chain. – In both structures the double stands and chains, respectively, are crosslinked by a network of hydrogen bonds.
KW - Amino acid complexes
KW - Calcium L‐aspartate dihydrate
KW - Calcium L‐aspartate tetrahydrate
KW - Hydrogen bonding
KW - L‐Asparatate complexes
UR - http://www.scopus.com/inward/record.url?scp=77949891107&partnerID=8YFLogxK
U2 - 10.1002/cber.19891220810
DO - 10.1002/cber.19891220810
M3 - Article
AN - SCOPUS:77949891107
SN - 0009-2940
VL - 122
SP - 1439
EP - 1444
JO - Chemische Berichte
JF - Chemische Berichte
IS - 8
ER -