Intramolecular Metal⋅⋅⋅π‐Arene Interactions in Neutral and Cationic Main Group Compounds

Abstract

The role of intramolecular metal⋅⋅⋅π‐arene interactions has been investigated in the solid‐state structures of a series of main group compounds supported by the bulky amide ligands, [N(tBuAr≠)(SiR3)]− (tBuAr≠=2,6‐(CHPh2)2‐4‐tBuC6H2, R=Me, Ph). The lithium and potassium amide salts showed different patterns of solvation and demonstrated that the SiPh3 substituent is able to be involved in stabilizing the electrophilic metal. These group 1 metal compounds served as ligand transfer reagents to access a series of bismuth(III) halides. Chloride extraction from Bi(N{tBuAr≠}{SiPh3})Cl2 using AlCl3 afforded the 1:1 salt [Bi(N{tBuAr≠}{SiPh3})Cl][AlCl4]. This was accompanied by a significant rearrangement of the stabilizing π‐arene contacts in the solid‐state. Attempted preparation of the corresponding tetraphenylborate salt resulted in phenyl‐transfer and generation of the neutral Bi(N{tBuAr≠}{SiPh3})(Ph)Cl.

Conjugated Bis‐Guanidines (CBGs) as β‐Diketimine Analogues: Synthesis, Characterization of CBGs/Their Lithium Salts and CBG Li Catalyzed Addition of B−H and TMSCN to Carbonyls

“…The N1−Li1 bond distance in compound 12 is 1.979(5) Å and is shorter than those in the lithium guanidinate (unsubstituted), LiN 3 H 4 (2.113(3) Å) [44] or [{Li(Mes)N} 2 SiMe 2 ] 2 (2.007(8) and 2.015(8) Å) [45] . The N1−Li1 bond distance in compound 12 is longer than those of Li‐cation stabilized amide ligands, [Li{(N( tBu Ar # )(SiMe 3 )}(Et 2 O) 2 ] (N−Li 1.944(2) Å) and [Li{N( tBu Ar # )(SiPh 3 )}(Et 2 O)], (N−Li 1.908(3) Å, (Ar #= bulky aromatic substituent) [40a] …”

Balancing Donor‐Acceptor and Dispersion Effects in Heavy Main Group Element π Interactions: Effect of Substituents on the Pnictogen⋅⋅⋅π Arene Interaction

“…[9] In addition to numerous examples showing intermolecular pnicogen···π arene interaction, systems with intramolecular interaction were less frequently reported, especially for bismuth. [10][11][12][13][14][15][16][17][18] However, these instances demonstrate that this rather weak interaction enables stabilization of unusual compounds and might support catalytic processes. [14] In order to rationalize what determines molecular and crystal structures, understanding the basic components of the pnictogen···π arene interaction is essential.…”

“…Furthermore, such weak interactions might also play a crucial role in some biological systems as discussed by Frontera and coworkers . In addition to numerous examples showing intermolecular pnicogen⋅⋅⋅π arene interaction, systems with intramolecular interaction were less frequently reported, especially for bismuth . However, these instances demonstrate that this rather weak interaction enables stabilization of unusual compounds and might support catalytic processes …”

Are Heavy Pnictogen‐π Interactions Really “π Interactions”?

“…Pnictogen‐π arene interactions have received considerable interest as structure‐forming and structure determining components in novel compounds, molecular and supramolecular assemblies [1–5] . For the lighter elements their potential for catalyst design was discussed more recently [6] .…”