Preparation of New Monoanionic “Scorpionate” Ligands: Synthesis and Structural Characterization of Titanium(IV) Complexes Bearing This Class of Ligand

The preparation of new “scorpionate” ligands in the form of the lithium derivatives [{Li(bdmpzdta)(H2O)}4] (1)
[bdmpzdta = bis(3,5-dimethylpyrazol-1-yl)dithioacetate], [Li(bdphpza)(H2O)(THF)] (2) [bdphpza = bis(3,5-diphenylpyrazol-1-yl)acetate], and [Li(bdphpzdta)(H2O)(THF)] (3) [bdphpzdta = bis(3,5-diphenylpyrazol-1-yl)dithioacetate]
has been carried out. Furthermore, a series of titanium complexes has been prepared by reaction of TiCl4(THF)2
with the lithium reagents [{Li(bdmpza)(H2O)}4] (4) [bdmpza = bis(3,5-dimethylpyrazol-1-yl)acetate] and 1. Under
the appropriate experimental conditions neutral complexes, namely [TiCl3(κ3-bdmpza)] (5), [TiCl3(κ3-bdmpzdta)]
(6), and [TiCl2(κ2-bdmpzdta)2] (7), and cationic complexes, namely [TiCl2(THF)(κ3-bdmpza)]Cl (8) and [TiCl2(THF)(κ3-bdmpzdta)]Cl (9), were isolated. Complexes 8 and 9 undergo an interesting nucleophilic THF ring-opening
reaction to give the corresponding alkoxide-containing species [TiCl2(κ3-bdmpza){O(CH2)4Cl}] (10) and [TiCl2(κ3-bdmpzdta){O(CH2)4Cl}] (11). A family of alkoxide-containing complexes of general formulas [TiCl2(κ3-bdmpza)(OR)] [R = Me (12); R = Et (14); R = iPr (16); R = tBu (18)] and [TiCl2(κ3-bdmpzdta)(OR)] [R = Me (13); R =
Et (15); R = iPr (17)] was also prepared. The structures of these complexes have been determined by spectroscopic
methods, and in addition, the X-ray crystal structures of 3, 7, 10, and 11 were also established.