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(mu4-O)2(mu4-OH)2(mu4-pz)2(kappa2-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((kappa3-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.