Magnesium amido N-heterocyclic carbene complexes

Abstract

Magnesium dications bind strongly to a tridentate anionic dicarbene ligand L = [N{CH(2)CH(2)(CNCHCHNMes)}(2)] forming dinuclear and trinuclear Mg complexes with some particularly short Mg-C bonds. Treatment of the proligand H(4)LCl(3) with three equivalents of methyl magnesium chloride or benzyl magnesium chloride affords Mg(3)(HL)Cl(6) in high yield. A suspension of in thf was heated to 80 degrees C for 2 h to afford Mg(2)(L)Cl(3), consistent with the loss of one equivalent of MgCl(2), and the deprotonation of the remaining acidic NH, lost as HCl gas. Treatment of Mg(3)(HL)Cl(6) with one equivalent of KC(8) results in deprotonation of the ligand amine NH to afford Mg(3)(L)Cl(5); treatment with a second equivalent forms the radical anion of the complex, K[Mg(3)(L)Cl(5)], which decomposes upon storage, precluding its structural characterisation. The acidic NH proton of the ligand in Mg(3)(HL)Cl(6) can also be removed by deprotonation with Li{N(SiMe(3))(2)}; additional equivalents of which also exchange the magnesium-bound chlorides for silylamido ligands, affording Mg(2)(L)Cl(2)N'' and Mg(2)(L)Cl(N'')(2), which have both been characterised by single-crystal X-ray diffraction studies.

Group 1 and 2 cyclic (alkyl)(amino)carbene complexes

“…The Mg(1)-C(1) distances of 2.2931(12) Å (1) and 2.2989(12) Å (2) compare with the longest reported values for Mg-NHC bond lengths (2.153-2.288 Å) 18,19. 1and S9-14 †).…”

Salt metathesis versus protonolysis routes for the synthesis of silylamide Hauser base (R2NMgX; X = halogen) and amido-Grignard (R2NMgR) complexes

“…(NHC 3 = [N{CH 2 CH 2 [NCHCHN(Mes)C]} 2 ], Mes = 2,4,6-trimethylphenyl), 20 are the only other structurally characterised Hauser bases supported by silylated amides. Furthermore, expanding the search to halide Hauser bases of any monodentate amide yields only a handful more examples.…”

N-heterocyclic carbene tethered amido complexes of palladium and platinum

“…Of note, tridentate bis(amido)-NHC [NCN] pincer complexes of zirconium and hafnium have been reported, 26,27 and amido-bis(NHC) [CNC] and amido-NHC [C,N] complexes of some early and late transition metals are also known. [28][29][30][31][32][33][34][35] Most closely related to this work, Douthwaite has described the palladium [CNC] complex A and, during the course of our research, Luo has reported the Pd complexes (B). 36,37 Fig .…”