Solid state study on rhenium dimethylphosphinoethane complexes: X-ray crystal structures of trans-[ReO2 (dmpe)2]PF 6·2H2O, trans-[ReO(OH)(dmpe)2](CF 3SO3)2, trans-[ReN(Cl)(dmpe) 2]CF3SO3 and trans-[ReCl2(dmpe) 2]ReO4

Article abstract of DOI:10.1081/SIM-200047553

The reaction of trans-[ReO₂(en)₂]Cl with dimethylphosphinoethane (dmpe) yielded the yellow complex trans-[ReO₂ (dmpe)₂]Cl (1), which, upon reaction with CF₃SO ₃H, yields orange crystals of the oxo-hydroxo complex trans-[ReO (OH)(dmpe)₂](CF₃SO₃)₂ (2). Reaction of trans-[ReNCl₂(PPh₃)₂] with dmpe resulted in orange crystals of trans-[ReN(Cl)(dmpe)₂]-CF₃SO ₃ (3). Adjustment of the pH of a solution of trans-[ReN(Cl)(dmpe) ₂]CF₃SO₃ to 11.7 with NaOH resulted in the formation of yellow crystals of trans-[ReCl₂(dmpe) ₂]ReO₄ (4). A shortening of the Re-P bond distances were observed as the axial ligands (i.e., core: O=Re^V-OH < O=Re ^V=O < N≡Re^V-Cl < Cl-Re^III-Cl) increased the electron density on the metal center, allowing for better Re-P π back bonding. The preliminary pK_a determination for the protonation of [ReO₂(dmpe)₂]⁺ to form [ReO(OH)(dmpe)₂]²⁺ showed the pK_a2 to be < 1. Crystallographic data: trans-[ReO₂(dmpe)₂]⁺: monoclinic space group P2₁/c with a = 11.5299(7) A, b = 15.2397(9) A, c = 15.0230(9) A, β = 97.7260(10)°, Z = 4; trans-[ReO(OH)(dmpe)₂]²⁺: monoclinic space group P2 ₁/c with a = 8.0426(4) A, b = 11.5472(6) A, c = 16.0303(8) A, β = 101.9360(10)°, Z = 2; trans-[ReN(Cl) (dmpe)₂]⁺: orthorhombic space group Pmc2₁ with a = 11.5068(10) A, b = 9.6656(8) A, c = 12.1772(11) A, Z = 2; trans-[Re(Cl)₂(dmpe)₂]⁺: monoclinic space group P2₁/c with a = 19.375(3) A, b = 8.6840(12) A, c = 15.910(2) A, β = 111.270(3)°, Z = 4. The conformation of the two dmpe ligands in all of the complexes described were λδ (eclipsed). Copyright