Group 4 Metal and Lanthanide Complexes in the Oxidation State +3 with Tris(trimethylsilyl)silyl Ligands.

A number of paramagnetic silylated d group 4 metallates were prepared by reaction of potassium tris(trimethylsilyl)silanide with group 4 metallates of the type K[CpMCl] (M = Ti, Zr, Hf). The outcomes of the reactions differ for all three metals. While for the hafnium case the expected complex [CpHf{Si(SiMe)}] was obtained, the analogous titanium reaction led to a product with two Si(H)(SiMe) ligands.

Open-shell lanthanide(II+) or -(III+) complexes bearing σ-silyl and silylene ligands: synthesis, structure, and bonding analysis.

Complexes featuring lanthanide (Ln)-Si bonds represent a highly neglected research area. Herein, we report a series of open-shell Ln(II+) and Ln(III+) complexes bearing σ-bonded silyl and base-stabilized N-heterocyclic silylene (NHSi) ligands. The reactions of the Ln(III+) complexes Cp3Ln (Ln = Tm, Ho, Tb, Gd; Cp = cyclopentadienide) with the 18-crown-6 (18-cr-6)-stabilized 1,4-oligosilanyl dianion [(18-cr-6)KSi(SiMe3)2SiMe2SiMe2Si(SiMe3)2K(18-cr-6)] (1) selectively afford the corresponding metallacyclopentasilane salts [Cp2Ln({Si(SiMe3)2SiMe2}2)](-)[K2(18-cr-6)2Cp](+) [Ln = Tm (2a), Ho (2b), Tb (2c), Gd (2d)].

Coordination Chemistry of Cyclic Disilylated Germylenes and Stannylenes with Group 11 Metals.

Reactions of EtP adducts of bissilylated germylenes and stannylenes with gold, silver, and copper cyanides led to cyanogermyl or -stannyl complexes of the respective metals. In the course of the reaction the phosphine moved to the metal, while the cyanide migrated to the low-coordinate group 14 element. The respective gold complexes were found to be monomeric, whereas the silver and copper complexes exhibited a tendency to dimerize in the solid state.

Coordination chemistry of disilylated stannylenes with group 10 d10 transition metals: silastannene vs stannylene complexation.

The coordination behavior of disilylated stannylenes toward zerovalent group 10 transition metal complexes was studied. This was accomplished by reactions of PEt3 adducts of disilylated stannylenes with zerovalent group 10 transition metal complexes. The thus obtained products differed between the first row example nickel and its heavier congeners.

Synthesis of Oligosilanyl Compounds of Group 4 Metallocenes with the Oxidation State +3.

Recently, we showed that titanocene silyls are much more stable with Ti in the oxidation state +3. The current study demonstrates that analogous Zr and Hf compounds can also be obtained by reaction of a suitable metalate precursor with an oligosilanyl dianion. As the obtained complexes formally possess a d(1) electron configuration, they were investigated using EPR spectroscopy.

Coordination chemistry of cyclic disilylated stannylenes and plumbylenes to group 4 metallocenes.

Reduction of group 4 metallocene dichlorides with magnesium in the presence of cyclic disilylated stannylene or plumbylene phosphine adducts yielded the respective metallocene tetrylene phosphine complexes. Under the same conditions the use of the respective dimerized stannylene or plumbylene gave metallocene ditetrylene complexes. A computational analysis of these reactions revealed for all investigated compounds multiple-bonded character for the M-E(II) linkage, which can be rationalized in the case of the monotetrylene complex with the classical σ-donor/π-acceptor interaction.

Dispersion energy enforced dimerization of a cyclic disilylated plumbylene.

By reaction of 1,4-dipotassio-1,1,4,4-tetrakis(trimethylsilyl)tetramethyltetrasilane with PbBr(2) in the presence of triethylphosphine a base adduct of a cyclic disilylated plumbylene could be obtained. Phosphine abstraction with B(C(6)F(5))(3) led to formation of a base-free plumbylene dimer, which features an unexpected single donor-acceptor PbPb bond. The results of density functional computations at the M06-2X and B3LYP level of theory indicate that the dominating interactions which hold the plumbylene subunits together and which define its actual molecular structure are attracting van der Waals forces between the two large and polarizable plumbylene subunits.

A cyclic disilylated stannylene: synthesis, dimerization, and adduct formation.

Reaction of 1,4-dipotassio-1,1,4,4-tetrakis(trimethylsilyl)tetramethyltetrasilane with [(Me(3)Si)(2)N](2)Sn led to the formation of an endocyclic distannene via the dimerization of a transient stannylene. In the presence of strong donor molecules such as PEt(3), the stannylene could be trapped as adduct. Reaction of the PEt(3) derivative with B(C(6)F(5))(3) gave rise to the formation of the stannylene B(C(6)F(5))(3) adduct.

The quest for silylhydroboranes: (Me(3)Si)(3)SiBH(2).

Reaction of BH(3)·NEt(3) with tris(trimethylsilyl)silylpotassium yielded the respective silylboranate. Abstraction of a hydride with B(C(6)F(5))(3) led to the neutral silylborane, which could be derivatised as an Et(3)N adduct. Treatment of the boranate with Cp(2)Ti(btmsa) resulted in exchange of THF coordinating to potassium by Cp(2)Ti(btmsa).