2-aminoisobutyric acid in Co(II) and Co(II)/Ln(III) chemistry: Homometallic and heterometallic clusters

摘要

The synthesis and magnetic properties of 13 new homo- and heterometallic Co(II) complexes containing the artificial amino acid 2-amino-isobutyric acid, aibH, are reported: [Co ~(II) _4(aib) _3(aibH) _3(NO _3)](NO _3) _4·2.8CH _3OH·0.2H _2O (1·2.8CH _3OH·0. 2H _2O), {Na 2[Co ~(II) 2(aib) 2(N _3) _4(CH _3OH) _4]} _n (2), [Co ~(II) _6La ~(III)(aib) _6(OH) _3(NO _3) 2(H _2O) _4(CH _3CN) 2]·0.5[La(NO _3) _6]·0.75(ClO _4)·1.75(NO _3)·3. 2CH _3CN·5.9H _2O (3·3.2CH _3CN· 5.9H _2O), [Co ~(II) _6Pr ~(III)(aib) _6(OH) _3(NO _3) _3(CH _3CN) _6]· [Pr(NO _3) 5]·0.41[Pr(NO _3) _3(ClO _4) _(0.5)(H _2O) 1.5]·0.59[Co(NO _3) _3(H _2O)] ·0.2(ClO _4)·0.25H _2O (4·0.25H _2O), [Co ~(II) _6Nd ~(III)(aib) _6(OH) _3(NO _3) _(2.8)(CH _3OH) _(4.7)(H _2O) 1.5]·2.7(ClO _4)·0.5(NO _3)·2.26CH _3OH·0. 24H _2O (5·2.26CH _3OH·0.24H _2O), [Co ~(II) _6Sm ~(III)(aib) _6(OH) _3(NO _3) _3(CH _3CN) _6]· [Sm(NO _3) 5]·0.44[Sm(NO _3) _3(ClO _4) _(0.5)(H _2O) 1.5] ·0.56[Co(NO _3) _3(H _2O)] ·0.22(ClO _4)·0.3H _2O (6·0.3H _2O), [Co ~(II) _6Eu ~(III)(aib) _6(OH) _3(NO _3) _3(CH _3OH) _4.87(H _2O) 1.13](ClO _4) 2.5(NO _3) _(0.5)·2.43CH _3OH· 0.92H _2O (7·2.43CH _3OH·0.92H _2O), [Co ~(II) _6Gd ~(III)(aib) _6(OH) _3(NO _3) 2.9(CH _3OH) _4.9(H _2O) 1.2]·2.6(ClO _4) ·0.5(NO _3)·2.58CH _3OH·0.47H _2O (8·2.58CH _3OH·0.47H _2O), [Co ~(II) _6Tb ~(III)(aib) _6(OH) _3(NO _3) _3(CH _3CN) _6]· [Tb(NO _3) 5]·0.034[Tb(NO _3) _3(ClO _4) _(0.5)(H _2O) _(0.5)] ·0.656[Co(NO _3) _3(H _2O)] ·0.343(ClO _4)·0.3H _2O (9·0.3H _2O), [Co ~(II) _6Dy ~(III)(aib) _6(OH) _3(NO _3) _(2.9)(CH _3OH) _4.92(H _2O) _(1.18)](ClO _4) _(2.6)(NO _3) _(0.5)·2.5CH _3OH·0.5H _2O (10·2.5CH _3OH·0. 5H _2O), [Co ~(II) _6Ho ~(III)(aib) _6(OH) _3(NO _3) _3(CH _3CN) _6]·0.27[Ho(NO _3) _3(ClO _4) _(0.35)(H _2O) 0.15]·0.656[Co(NO _3) _3(H _2O)] ·0.171(ClO _4) (11), [Co ~(II) _6Er ~(III)(aib) _6(OH) _4(NO _3) 2(CH _3CN) 2.5(H _2O) _(3.5)](ClO _4) _3·CH _3CN·0.75H _2O (12·CH _3CN·0. 75H _2O), and [Co ~(II) _6Tm ~(III)(aib) _6(OH) _3(NO _3) _3(H _2O) _6]·1.48(ClO _4)·1.52(NO _3) ·3H _2O (13·3H _2O). Complex 1 describes a distorted tetrahedral metallic cluster, while complex 2 can be considered to be a 2-D coordination polymer. Complexes _3-13 can all be regarded as metallo-cryptand encapsulated lanthanides in which the central lanthanide ion is captivated within a [Co ~(II) _6] trigonal prism. dc and ac magnetic susceptibility studies have been carried out in the 2-300 K range for complexes 1, 3, 5, 7, 8, 10, 12, and 13, revealing the possibility of single molecule magnetism behavior for complex 10.