Several oxidoborates, self-assembled from B(OH)
3 and templated by cationic Ni
(II) coordination compounds, were synthesized by crystallization from aqueous solution. These include the ionic compounds
trans-[Ni(NH
3)
4(H
2O)
2][B
4O
5(OH)
4]
.H
2O (
1), s-[Ni(dien)
2][B
5O
6(OH)
4]
2 (dien =
N-(2-aminoethyl)-1,2-ethanediamine (
2),
trans-[Ni(dmen)
2(H
2O)
2] [B
5O
6(OH)
4]
2.2H
2O (dmen =
N,N-dimethyl-1,2-diaminoethane) (
3), [Ni(HEen)
2][B
5O
6(OH)
4]
2 (HEen =
N-(2-hydroxyethyl)-1,2-diaminoethane) (
4), [Ni(AEN)][B
5O
6(OH)
4]
.H
2O (AEN = 1-(3-azapropyl) -2,4-dimethyl-1,5,8-triazaocta-2,4-dienato(1-)) (
5),
trans-[Ni(dach)
2(H
2O)
2][Ni(dach)
2] [B
7O
9(OH)
5]
2.4H
2O (dach = 1,2-diaminocyclohexane) (
6), and the neutral species
trans-[Ni(en)(H
2O)
2{B
6O
7(OH)
6}]
.H
2O (
7) (en = 1,2-diaminoethane), and [Ni(dmen)(H
2O){B
6O
7(OH)
6}]
.5H
2O (
8). Compounds
1–8 were characterized by single-crystal XRD studies and by IR spectroscopy and
2,
4–7 were also characterized by thermal (TGA/DSC) methods and powder XDR studies. The solid-state structures of all compounds show extensive stabilizing H-bond interactions, important for their formation, and also display a range of gross structural features:
1 has an insular tetraborate(2-) anion,
2–5 have insular pentaborate(1-) anions,
6 has an insular heptaborate(2-) anion (‘O
+’ isomer), whilst
7 and
8 have hexaborate(2-) anions directly coordinated to their Ni
(II) centers, as bidentate or tridentate ligands, respectively. The Ni
(II) centers are either octahedral (
1–4,
7,
8) or square-planar (
5), and compound
6 has both octahedral and square-planar metal geometries present within the structure as a double salt. Magnetic susceptibility measurements were undertaken on all compounds.
Full article