Hydrogen Bonding and Anion Binding in Structures of Tris(pyrazolyl)boratenickel(II) and Phosphate Esters

This paper presents the syntheses, crystal structures and spectroscopic properties of a series of nickel(II) complexes containing hydrotris(3,5‐dimethylpyrazolyl)borate and phosphate esters: [Tp*Ni(Hpz*) 2 (L)][(RO) 2 PO 2 ] [R = Et, Bu; L = H 2 O ( 1 ), (BuO) 2 P(O)OH ( 2 )] and [Tp*Ni(Hpz*)(H 2 O) 2 ][(EtO) 2 PO 2 ] ( 5 ) {Tp* = hydrotris(3,5‐dimethylpyrazolyl)borate, Hpz* = 3,5‐dimethylpyrazole}. The complexes [Ni(Tp*) 2 ] ( 3 ) and [(Tp*Ni) 2 (μ‐pz*)(μ‐OH)]( 4 ) were also prepared and fully characterized. X‐ray crystallographic studies of 1 and 2 reveal that the pyrazole moieties are hydrogen bonded to the guest phosphate ester anion. In complex 5 , the phosphate anion is hydrogen‐bonded by two O–H groups of the water molecules. Their behavior in solution was investigated by 1D and 2D 1 H NMR spectroscopic techniques. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)