Synthesis and Coordination Behavior of a New Hybrid Bidentate Ligand with Phosphine and Silylene Donors

Abstract

This work describes the synthesis and coordination behavior of a new mixed‐donor ligand PhC(NtBu)2SiC6H4PPh2 (1) containing both silylene and phosphine donor sites. Ligand 1 was synthesized from a reaction of ortho‐lithiated diphenylphosphinobenzene (LiC6H4PPh2) with chlorosilylene (PhC(NtBu)2SiCl). Treatment of 1 with Se and GeCl2 resulted in SiIV compounds 2 and 3 by selective oxidation of the silylene donor. This strong σ‐donor ligand induces dissociation of CuCl and PhBCl2 leading to formation of ionic complexes 4 and 5 respectively. The reaction of 1 with ZnCl2 and AlCl3 resulted in the formation of chelate complexes 5 and 7, respectively, while treatment with EtAlCl2 and GaCl3 forms monodentate complexes 8 and 9. X‐ray analysis of 4 showed that the copper is in the spiro center of the two five‐membered rings. Moreover, the copper(I)chloride has not been oxidized but dissociates to Cu+ and [CuCl2]−. All the compounds are well characterized by mass spectrometry, elemental analysis, NMR spectroscopy, and single‐crystal X‐ray diffraction studies.

New Types of Ge2 and Ge4 Assemblies Stabilized by a Carbanionic Dicarborandiyl-Silylene Ligand

“…The molecular structure of 1 established by a single-crystal X-ray diffraction analysis (Figure ) revealed that both Si and P atoms adopt a trigonal-pyramidal coordination geometry. The Si···P distance of 3.42 Å is slightly longer than that observed in 1,2-C 6 H 4 (PPh 2 ) Si (3.24 Å) . Owing to the steric congestion between the o -dicarborane cage and the silylene as well as the phosphine moiety, the Si–C [1.999(4) Å] and P–C [1.924(4) Å] distances are longer than the corresponding ones in 1,2-C 6 H 4 (PPh 2 ) Si [Si–C 1.932(2) Å, P–C 1.845(2) Å] …”

“…37 Owing to the steric congestion between the o-dicarborane cage and the silylene as well as the phosphine moiety, the Si−C [1.999(4) Å] and P−C [1.924(4) Å] distances are longer than the corresponding ones in 1,2-C 6 H 4 (PPh 2 )Si [Si−C 1.932(2) Å, P−C 1.845(2) Å]. 37 Dropwise addition of 1 molar equiv of GeCl 2 •dioxane dissolved in THF to a solution of 1 in THF at −20 °C resulted in a clear orange solution. The 1 H and 31 P{ 1 H} NMR spectra of the resulting solution indicate the formation of a mixture of multiple products.…”

“…The formation of PLSiCl 2 is reminiscent of the formation of 1,2-C 6 H 4 (PPh 2 )SiCl 2 , which resulted from the reaction of 1,2-C 6 H 4 (PPh 2 )Si with GeCl 2 . 37 Further fractional crystallization of the remaining reaction mixture in Et 2 O and THF as solvents enabled the isolation of the new compounds 2 and 3 in 14% and 21% yields based on the amount of 1 (Scheme 2).…”

“…34,35 The 31 P{ 1 H} NMR spectrum of 1 exhibits a signal at δ = 102.9 ppm, which is significantly low-field shifted relative to the phosphine silylene 1,2-C 6 H 4 (PPh 2 )Si (δ = −11.2 ppm) reported recently by the groups of Stalke and Roesky. 37 In contrast, the doublet in the 29 Si{ 1 H} NMR spectrum of 1 (δ = 17.5 ppm, 3 J (Si,P) = 81 Hz) lies very close to those of 1,2-C 6 H 4 (PPh 2 )Si (δ = 18.5 ppm) and o-dicarborandiyl-bridged bis-silylene SiLSi (δ = 18.9 ppm). 33 Compound 1 crystallized in Et 2 O as pale yellow crystals in the orthorhombic space group P2 1 2 1 2 1 .…”

“…The Si•••P distance of 3.42 Å is slightly longer than that observed in 1,2-C 6 H 4 (PPh 2 )Si (3.24 Å). 37 Owing to the steric congestion between the o-dicarborane cage and the silylene as well as the phosphine moiety, the Si−C [1.999(4) Å] and P−C [1.924(4) Å] distances are longer than the corresponding ones in 1,2-C 6 H 4 (PPh 2 )Si [Si−C 1.932(2) Å, P−C 1.845(2) Å]. 37 Dropwise addition of 1 molar equiv of GeCl 2 •dioxane dissolved in THF to a solution of 1 in THF at −20 °C resulted in a clear orange solution.…”