18583-59-0Relevant articles and documents
Synthesis, structural characterization, and properties of heavier alkaline earth complexes containing bis(pyrazolyl)borate or bis(3,5-diisopropylpyrazolyl) borate ligands
Saly, Mark J.,Heeg, Mary Jane,Winter, Charles H.
, p. 1330 - 1338 (2011)
Treatment of a solid mixture of KBH4 with six equivalents of 3,5-diisopropylpyrazole (iPr2pzH) at 180 °C afforded KTp iPr2(iPr2PzH)3 in 53% yield. KBpiPr2 was synthesized in 56% yield by treatment of a 1:2 M ratio of KBH4 and iPr2PzH in refluxing dimethylacetamide. Treatment of MI2 (M = Ca, Sr, Ba) with two equivalents of KBp or KBpiPr2 in tetrahydrofuran afforded MBp2(THF)2 (M = Ca, 64%, M = Sr, 81%), BaBp 2(THF)4 (32%), and M(BpiPr2) 2(THF)2 (M = Ca, 63%; M = Sr, 61%, M = Ba, 48%) as colorless crystalline solids upon workup. These complexes were characterized by spectral and analytical techniques and by X-ray crystal structure determinations of all complexes except KBpiPr2. KTpi Pr2(iPr2PzH)3 contains one κ3- N,N,N-TpiPr2 ligand and three κ1-iPr 2pzH ligands, with overall distorted octahedral geometry about the K ion. The iPr2PzH nitrogen-hydrogen bonds are engaged in intramolecular hydrogen bonding to the 2-nitrogen atoms of the Tp iPr2 ligand. The solid state structures of MBp 2(THF)2, BaBp2(THF)4, and M(Bp iPr2)2(THF)2 contain κ3-N,N,H Bp and BpiPr2 ligands, which form through metal-nitrogen bond formation to the 2-nitrogen atoms of the pyrazolyl fragments and metal-hydrogen bond formation to one boron-bound hydrogen atom per Bp ligand. SrBp2(THF)2has the shortest metal-hydrogen interactions among the series. A combination of preparative sublimations, solid state decomposition temperatures, and thermogravimetric analysis demonstrated that MBp2(THF)2, BaBp 2(THF)4, and M(BpiPr2) 2(THF)2 undergo solid state decomposition at moderate temperatures.
