Three-Coordinate Nickel(II) and Nickel(I) Thiolate Complexes Based on the β-Diketiminate Ligand System

Abstract

Mononuclear nickel(II) thiolate complexes [L(tBu)Ni(SEt)] (1) and [L(tBu)Ni(aet)] (2, aet = (-)S(CH2)2NH2) (L(tBu) = [HC(C((t)Bu)NC6H3((i)Pr)2)2](-)), supported by a bulky nacnac ligand, were synthesized by treatment of the nickel(II) bromide precursor [L(tBu)Ni(Br)] (I) with the potassium salts of ethanethiol and cysteamine, respectively. The nickel atom in 1 features a planar T-shaped environment, while the Ni ion within 2 shows a distorted square planar coordination geometry, as the aminoethanethiolate (aet) is coordinated as a chelating ligand. In 2 the β-diketiminate ligand binds in a rarely observed κ(2)C,N coordination mode. Reduction of complex 1 or its benzenethiolate analogue [L(tBu)Ni(SPh)] (II) by KC8 resulted in the formation of dinuclear Ni(I) thiolates (K·OEt2)(K)[L(tBu)Ni(SEt)]2 (3) and (K·OEt2)2[L(tBu)Ni(SPh)]2 (4), respectively. In these compounds [L(tBu)Ni(SR)](-) units are held together by potassium cations produced in the reduction process. All compounds mentioned were structurally characterized by single-crystal X-ray crystallography.

Synthesis of a “Masked” Terminal Nickel(II) Sulfide by Reductive Deprotection and its Reaction with Nitrous Oxide

“…Moreover, their 1 H NMR spectra are similar to those reported for other Ni II β -diketiminate thiolate complexes, such as [L tBu Ni(SPh)] and [L tBu Ni(SEt)]. [30,31]…”

“…Finally, the Ni-N distances in 3 - 5 are typical of those found in other three coordinate Ni II β -diketiminate complexes. [29-31,34]…”

Synthesis of a “Masked” Terminal Nickel(II) Sulfide by Reductive Deprotection and its Reaction with Nitrous Oxide

“…Moreover,t heir 1 HNMR spectra are similar to those reported for other Ni II b-diketiminate thiolate complexes,such as [L tBu Ni(SPh)] and [L tBu Ni(SEt)]. [30,31] Subsequent reduction of 1 and 2 with 2equiv of KC 8 in cold (À25 8 8C) Et 2 Oi nt he presence of 2equiv of 18-crown-6 results in the formation of [K(18-crown-6)][L R Ni(S)] (3:R= Me; 4:R= tBu). Complex 3 could be isolated as dark green blocks from hexanes/C 6 H 6 in 66 %y ield, whereas complex 4 was isolated as dark brown plates from toluene/isooctane in 88 %y ield.…”

“…Finally,the NiÀNdistances in 3-5 are comparable to those found in other three-coordinate Ni II b-diketiminate complexes. [29][30][31]34] TheN i ÀSb ond lengths in complexes 3, 4,a nd 5 are amongst the shortest known, and are intermediate between the additive covalent radii projected for nickel-sulfur single (2.13 ) and double bonds (1.95 ). [23,24,35] Forc omparison, [{L tBu Ni} 2 (m-S)], [30] [{(IPr)Ni} 2 (m-S) 2 ]( IPr = 1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene), [36] and [{PhB-(CH 2 StBu) 3 }Ni] 2 (m-S) [32] display comparable NiÀSb ond lengths of 2.0651(7), 2.0972(6), and 2.0714(4) , respectively, despite each possessing ab ridging S 2À ligand.…”

Trapping of an NiII Sulfide by a CoI Fulvene Complex

“…The Ni-S and C-S bond lengths of 2.181(2) Å and 1.870(7) Å, respectively, are both consistent with single bonds. 23,26 For comparison, the Ni-S bond length in the starting material is markedly shorter (2.0869(1) Å). 23 The Ni-N bond lengths in 1 (1.901 (4) Figure S6), which is also consistent with the proposed mechanism.…”