Hetero- and Homoleptic Magnesium Triazenides

Abstract

Using monoanionic triazenide ligands derived from biphenyl and m-terphenyl substituted triazenes Dmp(Tph)N 3 H (1a), (Me 4 Ter) 2 N 3 H (1b) or Dmp(Mph)N 3 H (1c) (Dmp = 2,6-Mes 2 C 6 H 3 with Mes = 2,4,6-Me 3 C 6 H 2 ; Me 4 Ter = 2,6-(3,5-Me 2 C 6 H 3 ) 2 C 6 H 3 ; Mph = 2-MesC 6 H 4 ; Tph = 2-TripC 6 H 4 with Trip = 2,4,6-i-Pr 3 C 6 H 2 ), several magnesium triazenides were synthesized. Heteroleptic complexes [Mg(N 3 Ar 2 )I(OEt 2 )] (Ar 2 = Dmp/Tph (2a), (Me 4 Ter) 2 (2b) were obtained from metalation of the corresponding triazenes with di-n-butylmagnesium followed by reaction with iodine in diethyl ether as the solvent in high yields. Replacing diethyl ether by n-heptane afforded trinuclear compounds [Mg 3 (N 3 Ar 2 ) 2 I 4 ] (3a, 3b) in low yields in which a central MgI 2 fragment is coordinated by two iodomagnesium triazenide moieties. Two unsolvated homoleptic magnesium compounds [Mg(N 3 Ar 2 ) 2 ] (4b, 4c) were obtained from di-n-butylmagnesium and triazenes 1b or 1c in a 1:2 ratio. Depending on the nature of the substituents, the magnesium center either shows the expected tetrahedral or a rather unusual square planar coordination.

A Blueprint for the Stabilization of Sub‐Valent Alkaline Earth Complexes**

“…Besides constrained square planar porphyrin complexes, a square planar geometry is a very rare coordination mode for the AE metals owing to the lack of crystal field stabilization. As a result there are a handful of near square planar magnesium complexes supported by nitrogen-based ligands in the literature, [70][71][72][73][74][75] and, to the best of our knowledge, only one example of a heavy AE complex in a square planar geometry, [Sr{N(SiMe 3 ) 2 } 2 (dioxane) 2 ] n (4) reported by Lappert and co-workers. [76] Therefore, we decided to use 4 as a model for expanding our strategy through S8); and in this case, this structural puckering seems necessary to accommodate the presence of the additional charge.…”

A Blueprint for the Stabilisation of Sub-valent Alkaline Earth Complexes

“…Besides constrained square planar porphyrin complexes, a square planar geometry is a very rare coordination mode for the AE metals owing to the lack of crystal field stabilization. As a result there are a handful of near square planar magnesium complexes supported by nitrogen-based ligands in the literature, [70][71][72][73][74][75] and, to the best of our knowledge, only one example of a heavy AE complex in a square planar geometry, [Sr{N(SiMe3)2}2(dioxane)2]n (4) reported by Lappert and co-workers. [76] Therefore, we decided to use 4 as a model for expanding our strategy through computational studies.…”

A Flexible, Extremely Sterically Demanding Triazenide Ligand: Synthesis and Coordination Chemistry

“…Extant examples are limited to simple aryl triazenides [15,16] as well as families of biphenyl and terphenylsubstituted triazenides (Figure 1). [9,10,[17][18][19][20][21][22][23][24][25] In contrast they have been popular ligands for transition metal chemistry, particularly for generating early transition metal paddlewheel type complexes with metal-metal bonds [26][27][28][29][30] as well as late-transition metal chelates. [31][32][33] Just as with their amidinate and guanidinate congeners, triazenide ligands display a range of monodentate and chelating coordination arrangements [34] but a metal triazenides in high yield.…”

“…This is in spite of the fact that simple triazenes have been known and used as ligands, for many decades. Extant examples are limited to simple aryl triazenides, as well as families of biphenyl and terphenyl‐substituted triazenides (Figure ) , , . In contrast they have been popular ligands for transition metal chemistry, particularly for generating early transition metal paddlewheel type complexes with metal‐metal bonds as well as late‐transition metal chelates .…”