Silver(I) and Nickel(II) Complexes with Oxygen‐ or Nitrogen‐Functionalized NHC Ditopic Ligands and Catalytic Ethylene Oligomerization.

Ren, Xiaoyu; Wesolek, Marcel; Bailly, Corinne; Karmazin, Lydia; Braunstein, Pierre

Potentially bidentate ditopic ligands containing a N‐heterocyclic carbene (NHC) donor associated with an ether or an amine have been prepared and coordinated to NiII centers. The influence of the length of the alkyl chain, –(CH2)2– or –(CH2)3– connecting the ether or the amine group to the heterocycle was examined. In the analogous AgI complexes [Ag{Im(Dipp)(C3OMe)‐κ1CNHC}2]Cl (8), 9 and 10, in the neutral NiII complexes with a C3 spacer trans‐[NiCl2{Im(Dipp)(C3OMe)‐κ1CNHC}2] (5a), 6, and 7, and in the cationic cis‐[Ni{Im(Dipp)(C3OMe)‐κ1CNHC}2(NCMe)2](PF6)2 (15) and cis‐[Ni{Im(Mes)(C3OMe)‐κ1CNHC}2(NCMe)2](PF6)2 (16), the ligand is monodentate. [(ImH)(Dipp)(C3OMe)][NiX3{Im(Dipp)(C3OMe)‐κ1CNHC}] (14a, X = Cl) and (14b, X = Br) are rare examples of complexes of the type [NiX3(NHC)]–. For comparison, [NiBr2{(Im)(Dipp)(C2NMe2)‐κ2,CNHC,Namine}] (24) and [NiBr2{(Im)(Dipp)(C3NMe2)‐κ2,CNHC,Namine}] (25) contain a six‐ or a seven‐membered κ2CNHC,Namine chelate, respectively. Various NiII complexes were evaluated as precatalysts for ethylene oligomerization. The structures of the carbene (Dipp)(C3OMe)imidazole‐ylidene (4) and of the complexes 5a, 7, 8, [(ImH)(Dipp)(C3OMe)]2[NiCl4] (11a), [(ImH)(Dipp)(C3OMe)]2[NiBr4] (11b), [(ImH)(Me)(C3OMe)]2[NiCl4] (13), 14b, 16·NCMe, [Im(H){C(Me)(=NDipp)}(C3OMe)]2 [NiCl4] (18), [AgCl{Im[C(Me)=NDipp](C3OMe)}‐κ1CNHC] (19), [AgCl{Im(Dipp)(C3NMe2)‐κ1CNHC}] (23), 24, 25 and trans‐[NiCl2{Im(Dipp){CH2CH2C(O)OEt}}2] were analyzed by X‐ray diffraction.

LIGANDS (Chemistry); OLIGOMERIZATION; ETHYLENE; NICKEL; SILVER

European Journal of Inorganic Chemistry, 2020, Vol 2020, Issue 11/12, p1073

1434-1948

Academic Journal

10.1002/ejic.201901064