Alternativ-Liganden XXXVIII. [1] Neue Versuche zur Synthese von Pd(0)- und Pt(0)-Komplexen des Tripod-Phosphanliganden FSi(CH₂CH₂PMe₂)₃ / Alternative Ligands XXXVIII. [1] Further Attempts to Synthesize Pd(0) and Pt(0) Complexes with the Tripod Phosphane Ligand FSi(CH₂CH₂PMe₂)₃

Abstract

The tripod phosphane ligand FSi(CH2CH2PMe2)3 (1) has been prepared again and attempts to generate F3CSi(CH2CH2PMe2)3 (2) were undertaken for the preparation of transition metal cage compounds of the type A(CCP)3M or A(CCP)3M-L (A = FSi, F3CSi). The photochemical addition of dimethylphosphane to trifluoromethyl-trivinylsilane, however, gave 1 instead of the expected CF3Sitripod ligand 2, obviously due to difluorocarbene elimination. 1 was used to prepare the chromium carbonyl derivative (CO)3Cr[(Me2PCH2CH2)3SiF] (3) from Cr(CO)3CHT, and 3 was characterized by NMR and IR spectroscopy. The novel complex FSi(CH2CH2PMe2)3Pd (4) and its PPh3 derivative [FSi(CH2CH2PMe2)3Pd]PPh3 (5) have been obtained by reacting 1 with Pd(PPh3)4 and were characterized by NMR (4) and X-ray diffraction (5). The data prove the expected Pd→Si interaction by characteristic coordination shifts and a Pd-Si distance of 3.875 Å which is smaller than the Ni-Si distance in the corresponding nickel compound (3.92 Å ). The preparation of the analogous platinum complex from the precursors Pt(PPh3)4, Pt(C7H10)3, or (Ph3P)2Pt(η2-C2H4) failed, whereas the reaction of 1 with Pt(PEt3)4 was successful, but surprisingly led to the trinuclear complex [FSi(CH2CH2PMe2)3Pt]3(PMe2CH2CH2)3SiF (6) with three cages of type 4 and an additional ligand 1 as a bridging unit. Complex 6 was isolated and characterized spectroscopically. Quantum chemical calculations have been used to elucidate the coordination geometry expected for 4, 5 and the corresponding platinum cage 4′ in 6. The calculations support the structure of 5 within the expected limitations of the experimental and theoretical methods and - in spite of the extremely soft coordination sphere of the studied cages - are in accord with the spectroscopic results.

(2-Pyridyloxy)silanes as Ligands in Transition Metal Coordination Chemistry

“…In this context, we need to note that a previous study by Bourissou et al [38] revealed an interaction between the Si-Si σ-bond electron pair of a disilane (as donor) and Cu(I) (as acceptor) (XIII). Similar systems (with rather weak d 10 metal-silicon interaction) have been investigated for Ni(0), Pd(0), and Pt(0) by Grobe et al (e.g., XIV) [39][40][41]. Whereas Au(I), Ni(0), Pd(0), and Pt(0) are more susceptible to phosphine ligands, Cu(I) represents a d 10 system likely to bind to more than one or two N-donor ligands, and thus we included Cu(I) (as CuCl) in our investigations.…”

Neutral and Anionic Square Planar Palladium(0) Complexes Stabilized by a Silicon Z‐Type Ligand

“…Analysis of single-crystals by X-ray diffraction revealed a SiÀ Pd bond length of 2.3707(6) Å in the T-shaped complex (Figure 2b), which is significantly shorter than the SiÀ Pd bond lengths for previously observed dative PdÀ Si bonds (Grobe et al: 3.875 Å, Bourissou et al: 2.9770(0) Å). [15] The SiÀ Pd bond length is even comparable to the PÀ Pd bonds (2.2909(6) and 2.2939(6) Å), indicating equal contributions of Pd by σ-acceptor (P-donors) and σdonor (Si-acceptor) interaction. The calculated ratio of bond-length and covalent radii (r = 0.95) is within the range of a Z-type interaction.…”