Synthesis of a homoleptic tris(silylene)-palladium(0) complex and a silylyne-bridged tetranuclear palladium cluster.

We report the reactions of an iminophosphonamido-silylene (1) with different palladium complexes. The reaction of 1 with [Pd(PPh3)4] furnished a homoleptic tris(silylene)-palladium(0) complex. In contrast, treatment of 1 with [PdMe2(tmeda)] led to the unprecedented formation of a non-planar µ3-silylyne-bridged tetranuclear palladium cluster that contains palladium atoms in different oxidation states.

Halogen-Exchange Reactions of Iminophosphonamido-Chlorosilylenes with Alkali Halides: Convenient Synthesis of Heavier Halosilylenes.

Halogen-substituted silylenes are an important building block for synthesizing silicon-based low-valent and multiple-bond species. However, the number of reports on heavier halosilylenes that contain bromine and iodine is still limited. Here, we present a convenient synthesis for bromo- and iodosilylenes supported by an iminophosphonamide ligand. The heavier halosilylenes [Ph2P(tBuN)2]SiX (2: X = Br, 3: X = I) were successfully synthesized via the halogen-exchange reaction of chlorosilylene 1 with alkali halides in THF. As a demonstration of the reactivity of 2 and 3, oxidative addition reactions of 2 and 3 with elemental selenium in C6D6 afforded the corresponding bromo- (5) or iodosilylene-selone (6) as colorless crystals. The molecular structures of 2, 3, 5, and 6 were fully characterized by spectroscopic means and single-crystal X-ray diffraction analysis. Furthermore, the effects of the halogen atom on the electronic state of halosilylenes 1-3 and halosilylene-selones 4-6 were investigated using density functional theory (DFT) calculations.

An Iminophosphonamido-Chlorosilylene as a Strong σ-Donating NHSi Ligand: Synthesis and Coordination Chemistry.

The N-heterocyclic silylene (NHSi) [Ph2 P(t BuN)2 ]SiCl (1), supported by an iminophosphonamide ligand, was obtained from the dehydrochlorination of [Ph2 P(t BuN)2 ]SiHCl2 (2) with LiN(SiMe3 )2 . NHSi 1 contains an extremely high-energy HOMO level and consequently displays unique coordination behavior toward RhI complexes. When 1 was treated with 1/4 of an equivalent of [RhCl(cod)]2 (cod=1,5-cyclooctadiene), the 14-electron Y-shaped bis(chlorosilylene) RhI complex 5 was obtained as dark purple crystals. The reaction of 1 with 1/6 of an equivalent of [RhCl(cod)]2 yielded the cationic tris(silylene)-RhI complex [6]+ ⋅Cl- as red crystals, wherein a two-coordinated silylene ligand engages in a Si=Rh double bond. A structural analysis of 5 and [6]+ ⋅Cl- revealed that the central rhodium atoms adopt trigonal and square-planar coordination geometries, respectively, with considerably shortened Si-Rh bonds [5: 2.1605(5) Å; [6]+ : 2.133(1) Å].