2-Acylpyrroles as mono-anionic O,N-chelating ligands in silicon coordination chemistry

A stable and true-blue emissive hexacoordinate Si(IV) N-heterocyclic carbene complex and its use in organic light-emitting diodes

A neutral hexacoordinate Si(IV) complex containing two tridentate N-heterocyclic carbene ligands is synthesised and characterized by X-ray crystallography, optical spectroscopy, electrochemistry and computational methods. The stable compound exhibits remarkable deep-blue photoluminescence particularly in the solid state, which enables its use as an electroluminescent material in organic light-emitting diodes.

Hydrosilylation of RN=CH Imino-Substituted Pyridines without a Catalyst

Treatment of the neutral pyridine-based ligands L¹ -L³ , bearing either one or two RN=CH imine moieties {where L¹ and L² are N,N-chelating ligands 2-(RN=CH)C₅ H₄ N (R=Ph (L¹ ) or R=2,4,6-Ph₃ C₆ H₂ (L² )) and L³ is the N,N,N-chelating ligand 2,6-(RN=CH)₂ C₅ H₃ N (R=2,6-iPr₂ C₆ H₃ )}, with HSiCl₃ yielded N→Si-coordinated silicon(IV) amides 2-{Cl₃ SiN(R)CH₂ }C₅ H₄ N (1, R=Ph; 2, R=2,4,6-Ph₃ C₆ H₂ ) and 2-{Cl₃ SiN(R)CH₂ }-6-(RN=CH)C₅ H₄ N (3, R=2,6-iPr₂ C₆ H₃ ). The organosilicon amides 1-3 are the products of spontaneous hydrosilylation of the RN=CH imine moiety induced by N→Si coordination of the proposed N,N-chelated chlorosilanes L¹ →SiHCl₃ (1 a), L² →SiHCl₃ (2 a), and L³ →SiHCl₃ (3 a). Furthermore, the reaction of L³ with an excess of HSiCl₃ provided the intramolecularly coordinated chlorosilicon diamide cyclo-{(C₅ H₃ N)-1,3-(CH₂ NR)₂ }SiCl₂ (4) (R=2,6-iPr₂ C₆ H₃ ) as the product of spontaneous reduction of both RN=CH imine moieties. The compounds have been characterized by NMR spectroscopy (1-4) and single-crystal X-ray diffraction analysis (1, 3, and 4). The mechanism of the hydrosilylation of the second RN=CH imine moiety in 3 by an excess of SiHCl₃ has also been studied. The experimental work is supplemented by DFT calculations.

Hydrosilylation in Aryliminopyrrolide-Substituted Silanes

A range of silanes was synthesized by the reaction of HSiCl3 with iminopyrrole derivatives in the presence of NEt3 . In certain cases, intramolecular hydrosilylation converts the imine ligand into an amino substituent. This reaction is inhibited by factors such as electron-donating substitution on Si and steric bulk. The monosubstituted ((Dipp) IMP)SiHMeCl ((Dipp) IMP=2-[N-(2,6-diisopropylphenyl)iminomethyl]pyrrolide), is stable towards hydrosilylation, but slow hydrosilylation is observed for ((Dipp) IMP)SiHCl2 . Reaction of two equivalents of (Dipp) IMPH with HSiCl3 results in the hydrosilylation product ((Dipp) AMP)((Dipp) IMP)SiCl ((Dipp) AMP=2-[N-(2,6-diisopropylphenyl)aminomethylene]pyrrolide), but the trisubsitituted ((Dipp) IMP)3 SiH is stable. Monitoring the hydrosilylation reaction of ((Dipp) IMP)SiHCl2 reveals a reactive pathway involving ligand redistribution reactions to form the disubstituted ((Dipp) AMP)((Dipp) IMP)SiCl as an intermediate. The reaction is strongly accelerated in the presence of chloride anions.

Tp*Cu(I)-CN-SiL2-NC-Cu(I)Tp*--a hexacoordinate Si-complex as connector for redox active metals via π-conjugated ligands

Hexacoordinate silicon complexes L2SiX2 (L = a 2-benzoylpyrrol-1-yl derivative, X = CN, NCS) were synthesized from L2SiCl2 by ligand exchange with trimethylsilyl reagents Me3SiX. In the presence of [Tp*CuNCMe] and Me3SiCN the silicon complex L2Si(NC(CuTp*))2 was obtained, which contains a linear Cu-CN-Si-NC-Cu unit (Tp* = hydrotris(3,5-dimethylpyrazolyl)borato).

Tetracoordinate silicon complexes of 1,2-bis(indol-2-yl)benzene as blue-emitting dyes in the solid state

1,2-Bis(indol-2-yl)benzene was prepared and found to serve as an effective bidentate ligand to form stable silicon complexes bearing two N–Si bonds.