Complexes of Aluminum and Gallium Halides with Dibutylamine: Structures and Properties

The reactions of dibutylamine (DBA) with aluminum tribromide and gallium trichloride (MX₃) in a benzene solution were studied using calorimetric and dielectrometric titration. The formation of stable and highly polar molecular complexes DBA · M₂X₆, DBA · MX₃, 2DBA · MX₃, and 6DBA · MX₃ was established.     

Palladium Clusters Pd4(SEt)4(OAc)4and Pd6(SEt)12: Structure and Properties

Palladium clusters Pd₄(SEt)₄(OAc)₄(I) and Pd₆(SEt)₁₂(II) were synthesized and studied. Their structure was determined by X-ray diffraction analysis. For I, a= 9.774(2) Å, b= 10.821(2) Å, c= 13.061(3) Å, = 92.88(3)°, V= 1379.6(5) ų, (calcd.) = 2.182 g/cm³, space group P2₁/n, Z= 4, N _ref= 1558, and R= 0.031; for II, a= 10.581(1) Å, b= 10.584(2) Å, c= 11.478(2) Å, = 101.62(1)°, = 104.95(1)°, = 106.74(1)°, V= 1135.2(4) ų, (calcd) = 2.007 g/cm³, space group P1, Z= 1, N _ref= 2828, and R= 0.022. In cluster I, four Pd atoms form a planar cycle. The neighboring palladium atoms are bound by two acetate or by two mercaptide bridges, the Pd···Pd distances being 3.036–3.195 Å. In cluster II, Pd atoms form a planar six-membered cycle with Pd···Pd distances of 3.083–3.127 Å. The neighboring palladium atoms are bound by two mercaptide bridges. The formation of analogous clusters in solution was confirmed by IR spectroscopy.     

Quantum-Chemical Calculations of Palladium(II) Complexes and Clusters

The structural parameters of stable palladium(II) compounds, namely, [Pd(-OAc)₂]₃, Pd(OAc)₂ · 2NHEt₂, [Pd(OAc)(-OAc)(CH₃)₂SO]₂, [Pd(-OAc)(-SEt)]₄, and [Pd(-SEt)₂]₆, were determined by relativistic and nonrelativistic calculations using the density functional method with account taken of all electrons or with the use of pseudopotentials. The gradient functional (PBE) and local density functional (LSDA) ensure good agreement between the calculated structural parameters of the Pd(II) complexes and clusters under study and data of X-ray diffraction analysis.     

Molecular and ionic forms of salts and H-complexes in solutions

We generalize data collected in recent years on the effect of the properties of the medium on the state of salts and H-complexes in solutions. We examine current ideas about the molecular structure of these compounds in low-polarity media and the role of solvation effects in stabilization of ionic forms. We show the interconnection between changes in the electronic structure of the salts and H complexes occurring under the influence of the solvent and the thermodynamics of respectively ionic dissociation and proton transfer.Devoted to the 100th anniversary of the birthday of Academician A. I. Brodskii.Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 31, No. 5, pp. 271–283, September–October 1995.