Octahedral Coordination Compounds of the Ni, Pd, Pt Triad

High-Valent Nickel Complexes Supported by a Functionalized PC(sp3)P Pincer Ligand: Properties and Catalysis

This article presents the synthesis and characterization of a series of robust high-valent organometallic nickel (Ni) complexes stabilized by a functionalized PC(sp3)P pincer ligand. Notably, the nickel center, covalently confined within the 3D ligand framework, demonstrates predictable coordination and redox behavior, coupled with remarkable stability across oxidation states +2, +3, and +4. These states were found to interconvert via one-electron transfer reactions. Among these complexes, the Ni(III)-PC(sp3)P species was identified as an efficient catalyst for the mild and selective hydrosilylation of alkenes, operating through a nonoxidative reaction mechanism.

Oxidation of germa- and stanna-closo-dodecaborate

The oxidation of closo-heteroborates [GeB11H11](2-) and [SnB11H11](2-) is presented. Upon oxidation germa-closo-dodecaborate yields a symmetrical dimer exhibiting a Ge-Ge bond between two clusters. This dimer shows sulphur insertion into the Ge-Ge bond at room temperature. In contrast, oxidation of the homologous tin cluster results in an unsymmetrical dimer bearing an Sn-B bond between two clusters. The Sn-B dimer is also the product of the hydride abstraction reaction. In the presence of the donor ligand 2,2'-bipyridine, the oxidation of closo-cluster [SnB11H11](2-) leads to the Sn(IV)-half sandwich coordination compound [bipy-SnB11H11] which dissolves in DMSO to give the Sn(IV)-adduct [bipy(DMSO)-SnB11H11].

Blue emitting undecaplatinum clusters

A blue luminescent 11-atom platinum cluster showing step-like optical features and the absence of plasmon absorption was synthesized. The cluster was purified using high performance liquid chromatography (HPLC). Electrospray ionization (ESI) and matrix assisted laser desorption ionization (MALDI) mass spectrometry (MS) suggest a composition, Pt11(BBS)8, which was confirmed by a range of other experimental tools. The cluster is highly stable and compatible with many organic solvents.

Dinuclear copper complexes: coordination of Group 14 heteroborates

The dinuclear copper(i) complex [Cu₂(μ-dmapm)(CH₃CN)₂][BF₄]₂ was reacted with Group 14 heteroborates. Four different coordination motives have been characterized.

Selenium adducts of germa- and stanna-closo-dodecaborate: coordination at platinum, structural studies and NMR spectroscopy

The selenium adducts of germa- and stanna-closo-dodecaborate can coordinate at platinum via the selenium atom and result in the products [Pt(dppp)(Se-TB(11)H(11))(2)](2-) (T = Ge, Sn) (dppp = 1,3-bis(diphenylphosphino)propane). The monomeric tin compound [Pt(dppp)(Se-SnB(11)H(11))(2)](2-) is converted to a dimeric complex [Pt(2)(dppp)(2)(μ(2),μ'(2)-η(2)-Se(2)SnB(11)H(11))]. The new compounds were characterized by NMR spectroscopy in solution ((1)H, (11)B, (13)C, (31)P, (77)Se, (119)Sn, (195)Pt), elemental analysis and single crystal X-ray diffraction.

Chalcogen chemistry of group(IV) closo-dodecaborates, synthesis, theory and coordination chemistry

Germa-closo-dodecaborate reacts with the elements sulfur, selenium and tellurium to give well defined products: [S-GeB(11)H(11)](2-), [Se-GeB(11)H(11)](2-) and [Te-GeB(11)H(11)](2-). The chalcogen adducts were characterized by single crystal structure analysis, NMR and IR spectroscopy. By using quantum chemical methods the nature of the germanium chalcogen bond was studied. Furthermore the first transition metal complexes of [S-GeB(11)H(11)](2-) and [S-SnB(11)H(11)](2-) with Pd and Pt were synthesized and characterized, showing that the dianionic chalcogen adducts can be used as new ligands in transition metal chemistry.

DFT studies of the σ-donor/π-acceptor properties of [SnCB10H11]– and its relationship to [SnCl3]–, CO, PF3, [SnB11H11]2–, SnC2B9H11, and related SnC2BnHn+2 compounds

The 1,2-carbastanna-closo-dodecaborate, [SnCB10H11]–, was found via DFT calculations to have intermediate σ-donor/π-acceptor properties between those of [SnB11H11]2– and 3,1,2-SnC2B9H11, and quite similar HOMO and LUMO energies and shapes to those of [SnCl3]–, which is a stronger σ-donor and weaker π-acceptor than CO or PF3. The non-carbon containing cluster [SnB11H11]2– is shown to be a very strong donor, whereas the dicarbon cluster 3,1,2-SnC2B9H11 is a poor σ-donor but good Lewis acid, consistent with experimental results. Thus, these systems can be tuned across a very wide range via isolobal replacement of [BH]– for CH vertices. The higher negative charge in the non-carbon-containing systems, as well as the fact that boron is more electropositive than carbon, contribute to the increased energies of both HOMO and LUMO in the stannaboranes compared to the stannacarboranes, explaining their relative donor and acceptor properties.Key words: DFT calculations, tin, borane cluster.