Nickel(ii)-mediated cyanamide–pyrazole coupling highlights distinct reactivity of NCNR2 and NCR nitrile ligands

The nickel(ii) center efficiently promotes the cyanamide–pyrazole coupling to give bis-chelate and tris-chelate products. The formation of the tris-chelate product for dialkylcyanamides is thermodynamically favorable.

Ni(ii) complexes of the phosphine-oxime Ph2PC6H4-2-CH[double bond, length as m-dash]NOH

We report the solution and structural chemistry of nickel(ii) complexes of the phosphine-oxime Ph2PC6H4-2-CH[double bond, length as m-dash]NOH (PCH[double bond, length as m-dash]NOH). PCH[double bond, length as m-dash]NOH invariably binds in a bidentate manner as illustrated by cis-Ni(PCH[double bond, length as m-dash]NOH)2Cl2 and cis-[Ni(PCH[double bond, length as m-dash]NOH)2]2+ (as its BF4- salt). Treatment of PCH[double bond, length as m-dash]NOH with Ni(OAc)2(H2O)4 gave charge-neutral trans-[Ni(PCH[double bond, length as m-dash]NO)2]0. Treatment of trans-[Ni(PCH[double bond, length as m-dash]NO)2]0 with BF3 gave [Ni(PCH[double bond, length as m-dash]NO)2BF2]BF4. The cation features a planar NiP2N2 center wherein the pair of oximate groups are linked by the difluoroboryl center. The 1 : 1 complexes of the oxime and the oximate are illustrated by [Ni(PCH[double bond, length as m-dash]NOH)Cl2]2 and [Ni(C6F5)(PCH[double bond, length as m-dash]NO)]2, which feature five- and four-coordinate Ni(ii) centers, respectively. All complexes in this series hydrolyze to give the trinickel oxo-phosphine-oximate complex [Ni3(PCH[double bond, length as m-dash]NO)3O]+. One feature of the PCH[double bond, length as m-dash]NOH ligand is its wide bite angle combined with its protic OH center. These aspects are manifested in the structures of Ni(PCH[double bond, length as m-dash]NOH)2Cl2 and [Ni(PCH[double bond, length as m-dash]NOH)Cl2]2, which show intramolecular hydrogen bonding to terminal chloride ligands.

Metal-Involving Synthesis and Reactions of Oximes

This review classifies and summarizes the past 10-15 years of advancements in the field of metal-involving (i.e., metal-mediated and metal-catalyzed) reactions of oximes. These reactions are diverse in nature and have been employed for syntheses of oxime-based metal complexes and cage-compounds, oxime functionalizations, and the preparation of new classes of organic species, in particular, a wide variety of heterocyclic systems spanning small 3-membered ring systems to macroheterocycles. This consideration gives a general outlook of reaction routes, mechanisms, and driving forces and underlines the potential of metal-involving conversions of oxime species for application in various fields of chemistry and draws attention to the emerging putative targets.

A novel family of homoleptic copper(i) complexes featuring disubstituted cyanamides: a combined synthetic, structural, and theoretical study

Homoleptic copper(i) complexes featuring disubstituted cyanamides were obtained and characterized using experimental methods and their properties were studied theoretically.

Metal-mediated reactions between dialkylcyanamides and acetamidoxime generate unusual (nitrosoguanidinate)nickel(ii) complexes

Nitrosoguanidinate Ni^II complexes were generated via a hitherto unreported reaction between nickel(ii) salts, N,N-disubstituted cyanamides NCNR₂, and the amidoxime MeC(NOH)NH₂ in MeOH.