Lithium, Titanium, and Zirconium Complexes with Novel Amidinate Scorpionate Ligands

The reaction of bis(3,5-dimethylpyrazol-1-yl)methane (bdmpzm) with BunLi and carbodiimide derivatives, namely,
N,N‘-diisopropyl, dicyclohexyl, and 1-tert-butyl-3-ethyl carbodiimides, enables the preparation of new heteroscorpionate
ligands in the form of the lithium derivatives [Li(NNN)(THF)] (NNN = pbpamd (1) (pbpamd = N,N‘-diisopropylbis(3,5-dimethylpyrazol-1-yl)acetamidinate); cbpamd (2) (cbpamd = N,N‘-dicyclohexylbis(3,5-dimethylpyrazol-1-yl)acetamidinate); and tbpamd (3) (tbpamd = N-ethyl-N‘-tert-butylbis(3,5-dimethylpyrazol-1-yl)acetamidinate)), although
a similar process with N,N‘-dimethylcarbodiimide gave the dinuclear complex [Li(bpzii)(THF)]2 (4) (bpzii =
N-(dimethylamino)-N‘-[(dimethylamino)bis(3,5-dimethylpyrazol-1-yl)methylimino]imino). When this last reaction was
carried out in an air atmosphere, the cluster complex [Li8(μ4-O)2(μ4-OH)2(μ4-pz)2(κ2-bpziLi)2(bpzCN)2(THF)4] (5)
(bpziLi = dimethylaminobis(3,5-dimethylpyrazol-1-yl)methyliminolithium, bpzCN = bis(3,5-dimethylpyrazol-1-yl)acetonitrile) was isolated and characterized by X-ray analysis. Finally, when the same process was carried out in
the presence of water the amidine−scorpionate (bpzan) (6) (bpzan = N,N-dimethylbis(3,5-dimethylpyrazol-1-yl)acetamidine) was obtained. Compounds 1 and 3 reacted with [TiCl4(THF)2] or [ZrCl4] to give complexes of
stoichiometry [MCl3((κ3-NNN))] (M = Ti, Zr) (7−10). The structures of the different compounds were determined by
spectroscopic methods and, in addition, the X-ray crystal structures of 1, 3, 4, 5, and 6 were also established.