Synthesis and Characterization of a Thiopyridazinylmethane-Based Scorpionate Ligand: Formation of Zinc Complexes and Rearrangement Reaction

Synthesis, Structure, and Reactivity of a Terminal Cadmium Hydride Compound, [κ3-TismPriBenz]CdH

The terminal cadmium hydride compound, [κ³-Tism^PriBenz]CdH, which features the tris[(1-isopropylbenzimidazol-2-yl)dimethylsilyl]methyl ligand, may be obtained via the reactions of either [κ³-Tism^PriBenz]CdN(SiMe₃)₂ or [Tism^PriBenz]CdOSiPh₃ with PhSiH₃. The Cd-H bond of [κ³-Tism^PriBenz]CdH undergoes (a) metathesis reactions with MeI, Me₃SiX (X = Cl, Br, I, NCO), and Me₃SnX (X = Cl, Br, I) to afford the corresponding [Tism^PriBenz]CdX derivative, (b) insertion with CO₂ and CS₂ to afford respectively [Tism^PriBenz]Cd(κ¹-O₂CH) and [Tism^PriBenz]Cd(κ¹-S₂CH), and (c) hydride abstraction with B(C₆F₅)₃ to afford {[Tism^PriBenz]Cd}[HB(C₆F₅)₃] that possesses a rare trigonal monopyramidal geometry for cadmium.

Mono- and Hexanuclear Zinc Halide Complexes with Soft Thiopyridazine Based Scorpionate Ligands

Scorpionate ligands with three soft sulfur donor sites have become very important in coordination chemistry. Despite its ability to form highly electrophilic species, electron-deficient thiopyridazines have rarely been used, whereas the chemistry of electron-rich thioheterocycles has been explored rather intensively. Here, the unusual chemical behavior of a thiopyridazine (6-tert-butylpyridazine-3-thione, HtBuPn) based scorpionate ligand towards zinc is reported. Thus, the reaction of zinc halides with tris(6-tert-butyl-3-thiopyridazinyl)borate Na[TntBu] leads to the formation of discrete torus-shaped hexameric zinc complexes [TntBuZnX]6 (X = Br, I) with uncommonly long zinc halide bonds. In contrast, reaction of the sterically more demanding ligand K[TnMe,tBu] leads to decomposition, forming Zn(HPnMe,tBu)2X2 (X = Br, I). The latter can be prepared independently by reaction of the respective zinc halides and two equiv of HPnMe,tBu. The bromide compound was used as precursor which further reacts with K[TnMe,tBu] forming the mononuclear complex [TnMe,tBu]ZnBr(HPnMe,tBu). The molecular structures of all compounds were elucidated by single-crystal X-ray diffraction analysis. Characterization in solution was performed by means of 1H, 13C and DOSY NMR spectroscopy which revealed the hexameric constitution of [TntBuZnBr]6 to be predominant. In contrast, [TnMe,tBu]ZnBr(HPnMe,tBu) was found to be dynamic in solution.