Multiple Bonds between Transition Metals and Main-Group Elements. 142.¹ Lewis-Base Adducts of Organorhenium(VII) Oxides: Structures and Dynamic Behavior in Solution

Organorhenium(VII) oxides such as methyltrioxorhenium(VII) (1) and its longer-chain alkyl derivatives form 1:1 and 1:2 adducts with nitrogen-donor Lewis bases. These compounds adopt well-defined structures in the solid state. In solution, they undergo exchange of both the metal-coordinated base ligands and the oxo ligands. The synthesis and crystal structure (X-ray diffraction study) of the amino-functionalized complex O₃Re-CH₂CH₂CH₂N(C₅H₁₀) (3a) is reported. Crystal data are as follows: monoclinic, space group P2₁/c, a = 8.327(2) Å,b= 11.516(1) AÅ, c = 10.864(2) Å, β = 101.54(7)°, R = 0.028 for 1747 reflections. Compounds of type 3a are intramolecular base adducts in the solid state, but rigid geometries in solution can only be observed at low temperatures.