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The reaction of different types of bis(pyrazol-1-yl)methane derivatives with BunLi and alkyl or aryl-containing-isocyanates or isothiocyanates, some of these as chiral reagents, gives rise to the preparation of new heteroscorpionate ligands in the form of the lithium derivatives [Li(NNE)]2 (1–10), although a similar process with trimethylsilyl isocyanate or isothiocyanate gave the complexes [Li(NCX)(bdmpzs)(THF)] (X = O, 11; X = S, 12) [bdmpzs = bis(3,5-dimethylpyrazol-1-yl)trimethylsilylmethane]. Compounds 1–8 reacted with [TiCl4(THF)2] or [MCl4] (M = Zr, Hf) to give a series of cationic complexes [MCl3{κ3-NNE(H)}]Cl (13–36) where the heteroscorpionate ligand contains either an acetamide or thioacetamide group resulting from the protonation of the corresponding acetamidate or thioacetamidate. However, under appropriate experimental conditions neutral Ti complexes were isolated—namely [TiClx(NMe2)3−x(S-mbbpam)] (37–39) [S-mbbpam = (S)-(−)-N-α-methylbenzyl-2,2-bis(3,5-dimethylpyrazol-1-yl)acetamidate]. Finally, two alkoxide-containing titanium complexes [TiClx(OR)3−x(S-mbbpamH)]Cl (40–41) were also prepared. The structures of these complexes have been determined by spectroscopic methods and, in addition, the X-ray crystal structures of 1, 12, and 19 were also established.

The reaction of [Ti(NR)Cl(2)(py)(3)](R = (t)Bu, p-tolyl, 2,6-C(6)H(3)(i)Pr(2)) with [{Li(bdmpza)(H(2)O)}(4)][bdmpza = bis(3,5-dimethylpyrazol-1-yl)acetate] and [{Li(bdmpzdta)(H(2)O)}(4)][bdmpzdta = bis(3,5-dimethylpyrazol-1-yl)dithioacetate] affords the corresponding complexes [Ti(NR)Cl(kappa(3)-bdmpzx)(py)](x = a, R = (t)Bu 1, p-tolyl 2, 2,6-C(6)H(3)(i)Pr(2) 3; x = dta, R =(t)Bu 4, p-tolyl , 2,6-C(6)H(3)(i)Pr(2) 6), which are the first examples of imido Group 4 complexes stabilized by heteroscorpionate ligands. The solid-state X-ray crystal structure of 1 has been determined. The titanium centre is six-coordinate with three fac-sites occupied by the heteroscorpionate ligand and the remainder of the coordination sphere being completed by chloride, imido and pyridine ligands. The complexes are 1-6 fluxional at room temperature. The pyridine ortho- and meta-proton resonances show evidence of dynamic behaviour for this ligand and variable-temperature NMR studies were carried out in order to study their dynamic behaviour in solution. The complexes [Nb(NR)Cl(3)(py)(2)](R = (t)Bu, p-tolyl, 2,6-C(6)H(3)(i)Pr(2)) reacted with [{Li(bdmpza)(H(2)O)}(4)] and (Hbdmpze)[bdmpze = 2,2-bis(3,5-dimethylpyrazol-1-yl)ethoxide], the latter with prior addition of (n)BuLi, to give the complexes [Nb(NR)Cl(2)(kappa(3)-bdmpzx)](x = a, R =(t)Bu 7, p-tolyl 8, 2,6-C(6)H(3)(i)Pr(2) 9; x = e, R = (t)Bu 10, p-tolyl 11, 2,6-C(6)H(3)(i)Pr(2)) 12 and these are the first examples of imido Group 5 complexes with heteroscorpionate ligands. The structures of these complexes have been determined by spectroscopic methods.