Zöe R. Bell, Graham R. Motson, J. Jeffery
Jun 30, 2001
Citations
0
Influential Citations
11
Citations
Journal
Polyhedron
Abstract
Abstract Two new poly(pyrazolyl)borate ligands have been prepared: potassium tris[3-{(4-tbutyl)-pyrid-2-yl}-pyrazol-1-yl]hydroborate (KTpBuPy) which has three bidentate arms and is therefore hexadentate; and potassium bis[3-(2-pyridyl)-5-(methoxymethyl)pyrazol-1-yl]-dihydroborate (KBp(COC)Py) which has two bidentate arms and is therefore tetradentate. The crystal structures of their lanthanide complexes [La(TpBuPy)(NO3)2] and [La(Bp(COC)Py)2X] (X=nitrate or triflate) have been determined. In [La(TpBuPy)(NO3)2] the metal ion is ten-coordinate, from the hexadentate N-donor podand ligand and two bidentate nitrates. [La(Bp(COC)Py)2(NO3)] is also ten-coordinate, from two tetradentate ligands and a bidentate nitrate, but in [La(Bp(COC)Py)2(CF3SO3)] the metal ion is nine-coordinate because the triflate anion is monodentate. Two unexpected new complexes which arose from partial decomposition of the poly(pyrazolyl)borate ligands have also been characterised structurally. In [La(BuPypzH)3(O3SCF3)3] the metal ion is nine-coordinate from three bidentate pyrazolyl-pyridine arms (liberated by decomposition of KTpBuPy) and three triflate anions; there is extensive NH· · · O hydrogen-bonding between the pyrazolyl and triflate ligands. [Nd(TpPy)(BpPy)][Nd(PypzH)(NO3)4] was isolated from the reaction of hexadentate tris[3-(2-pyridyl)-pyrazol-1-yl]hydroborate (TpPy) with Nd(NO3)3. One of the TpPy ligands has lost one bidentate pyrazolyl-pyridine ‘arm’ (PypzH) to leave tetradentate tris[3-(2-pyridyl)-pyrazol-1-yl]dihydroborate (BpPy). In this structure, the cation [Nd(TpPy)(BpPy)]+ is ten-coordinate from inter-leaved hexadentate and tetradentate ligands, and the anion [Nd(PypzH)(NO3)4]− is also ten-coordinate from the bidentate N-donor ligand PypzH and four bidentate nitrates.