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Complexation Properties of Heteroditopic Cryptands towards Cu 2+ , Zn 2+ , Cd 2+ , and Pb 2+ in Aqueous Solution: Crystal Structures of [(H 5 L1)(ClO 4 ) 5 ]·4 H 2 O and [(NiL2Cl)Cl]·5.5 H 2 O·CH 3 OH
Author(s) -
Bazzicalupi Carla,
Bandyopadhyay Prasun,
Bencini Andrea,
Bianchi Antonio,
Valtancoli Barbara,
Bharadwaj Dulali,
Bharadwaj Parimal K.,
Butcher Ray J.
Publication year - 2000
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/1099-0682(200009)2000:9<2111::aid-ejic2111>3.0.co;2-u
Subject(s) - cryptand , chemistry , protonation , crystallography , monoclinic crystal system , metal , aqueous solution , ion , crystal structure , molecule , denticity , trigonal bipyramidal molecular geometry , stereochemistry , metal ions in aqueous solution , inorganic chemistry , organic chemistry
The protonation and metal ion (Cu 2+ , Zn 2+ , Cd 2+ , Pb 2+ ) complexation abilities of three heteroditopic cryptands in solution are described and the relevant equilibrium constants are reported. The two distinct binding subunits of the ligands act cooperatively in the coordination of M(H 2 O) 2+ (M = metal ion) species. The cryptand L1 binds five protons in very acidic solution and crystallizes as [(H 5 L1 )(ClO 4 ) 5 ]·4 H 2 O in the monoclinic space group P 2 1 / n with a = 14.281(4), b = 14.313(7), c = 24.082(8) Å, β = 92.00(2)°, Z = 4, R = 0.079, and wR 2 = 0.2010. The molecule shows an endo ‐ endo conformation with a pseudo‐threefold symmetry axis passing through the two bridgehead nitrogen atoms. All the cryptands ( L1 − L3 ) readily form inclusion complexes with Cu 2+ , Ni 2+ , Zn 2+ , Cd 2+ , and Pb 2+ ions at the tren end of the cavity. The crystal structure of [(Ni L2 Cl)Cl]·5.5 H 2 O·CH 3 OH is also reported [ C 2/ c , a = 26.671(6), b = 16.784(4), c = 18.591(8) Å, β = 101.006(14)°, Z = 8, R = 0.091, and wR 2 = 0.1424]. The Ni II ion resides in a trigonal‐bipyramidal coordination environment with the equatorial sites occupied by the three secondary nitrogen atoms of the cryptand and the axial sites occupied by a bridgehead nitrogen atom and a Cl − ion.