P4-Liganden mit maximaler Elektronendonorfähigkeit

Coordination Behavior of [Cp''2 Zr(η1:1 -P4 )] towards Different Lewis Acids

A detailed method for the preparation of [Cp''₂ Zr(η^1:1 -P₄ )] (1) is presented. The coordination behavior of 1 towards Lewis acidic transition metal complexes of tungsten, manganese, and iron, respectively, and main group compounds (AlMe₃ , AlEt₃ ) was investigated in detail by computational and experimental studies. In doing so, a series of unprecedented complexes with different coordination modes and multiple coordination numbers of the tetraphosphabicyclo[1.1.0]butane framework were synthesized. All products, as well as the starting materials, were comprehensively characterized by NMR spectroscopy, mass spectrometry, elemental analysis, and single crystal X-ray structural analysis.

A neutral tetraphosphacyclobutadiene ligand in cobalt(I) complexes

The unusual reactivity of the newly synthesized β-diketiminato cobalt(I) complexes, [(L(Dep)Co)2] (2 a, L(Dep)=CH[C(Me)N(2,6-Et2C6H3)]2) and [L(Dipp)Co⋅toluene] (2 b, L(Dipp)=CH[CHN(2,6-(i)Pr2C6H3)]2), toward white phosphorus was investigated, affording the first cobalt(I) complexes [(L(Dep)Co)2(μ2:η(4),η(4)-P4)] (3 a) and [(L(Dipp)Co)2(μ2:η(4),η(4)-P4)] (3 b) bearing the neutral cyclo-P4 ligand with a rectangular-planar structure. The redox chemistry of 3 a and 3 b was studied by cyclic voltammetry and their chemical reduction with one molar equivalent of potassium graphite led to the isolation of [(L(Dep)Co)2(μ2:η(4),η(4)-P4)][K(dme)4] (4 a) and [(L(Dipp)Co)2(μ2:η(4),η(4)-P4)][K(dme)4] (4 b). Unexpectedly, the monoanionic Co2P4 core in 4 a and 4 b, respectively, contains the two-electron-reduced cyclo-P4(2-) ligand with a square-planar structure and mixed-valent cobalt(I,II) sites. The electronic structures of 3 a, 3 b, 4 a, and 4 b were elucidated by NMR and EPR spectroscopy as well as magnetic measurements and are in agreement with results of broken-symmetry DFT calculations.