Fourteen‐Electron Bis(dialkylsilylene)palladium and Twelve‐Electron Bis(dialkylsilyl)palladium Complexes

Abstract

Hydrogens make a difference: The first 14‐electron bis(silylene)palladium (A) and 12‐electron bis(silyl)palladium complexes (B) are synthesized from a stable dialkylsilylene (see picture; gold: Pd; dark blue: Si; light blue: C; magenta: H). The remarkable difference between the L‐M‐L angles of these two complexes is rationalized by applying the Walsh diagram.

Planar PtPd3 Complexes Stabilized by Three Bridging Silylene Ligands

“…Figure shows the 29 Si{ 1 H} NMR peak positions and the Pt−Si bond lengths of the complexes with a bond between the silylene ligands and Pt, [(Cy 3 P) 2 Pt=Si(C 6 H 2 Me 3 ‐2,4,6) 2 ], 1 , 3 , 5 , and [{Pt(dmpe)} 2 (μ‐SiPh 2 ) 2 ] ((a)–(e)). Data for the tetrapalladium complexes 2 , bissilylene palladium(0) complex, and the Pd 4 Si 5 complex are also plotted ((f)‐(h)). A negative correlation is observed among the complexes, and the bond lengths and the NMR peak positions of complexes 1 , 2 , 3 , and 5 are between those of the mononuclear silylene–platinum complex (a) and the diplatinum complex with bridging silylene ligands (e).…”

An isolable dialkylsilylene and its derivatives. A step toward comprehension of heavy unsaturated bonds

“…1. 20 Thus, the HOMO-LUMO gap in diaminosilylene 2 0 is much larger than that in dialkylsilylene 6 0 . The LUMO level of 2 0 is much higher than that of 6 0 due to the interaction of the vacant 3p orbital at the divalent silicon with neighboring nitrogen lone-pair orbitals.…”

“…of bis(tricyclohexylphosphine)palladium at room temperature affords the corresponding bis(silylene)palladium 31 in 40% isolated yield (eqn (10)). 20 The products however depend strongly on the silylene/Pd ratio. When the molar ratio is 1/1, monosilylene complex 32 is formed in a high yield as an air-sensitive purple oil but the isolation was unsuccessful due to the contamination of free tricyclohexylphosphine (eqn (11)).…”

“…When the molar ratio is 1/1, monosilylene complex 32 is formed in a high yield as an air-sensitive purple oil but the isolation was unsuccessful due to the contamination of free tricyclohexylphosphine (eqn (11)). 20,47 The reaction of 6 with (Cy 3 P) 2 Pd at the ratio o1/2 gives an interesting dinuclear palladium complex 33 with a bridging dialkylsilylene ligand (eqn ( 12)). 47 ð10Þ ð11Þ ð12Þ Interestingly, bis(silylene)complex 31 reacts with molecular hydrogen in benzene-d 6 at room temperature to give an unprecedented 12-electron dicoordinate palladium complex 34, as orange crystals (eqn ( 13)).…”

“…47 ð10Þ ð11Þ ð12Þ Interestingly, bis(silylene)complex 31 reacts with molecular hydrogen in benzene-d 6 at room temperature to give an unprecedented 12-electron dicoordinate palladium complex 34, as orange crystals (eqn ( 13)). 20 ð13Þ Although ligands in dicoordinate palladium complexes 31 and 34 have similar bulkiness, the molecular geometries are very different to each other; two silylenes in 31 coordinate linearly to palladium but the Si-Pd-Si angle in 34 is very narrow with the angle of 971. 20 The structural difference between the two dicoordinate palladium complexes is explained using a modified Walsh diagram.…”