Solid State Study on Rhenium Dimethylphosphinoethane Complexes: X-ray Crystal Structures of trans-[ReO_2(dmpe)_2]PF_6 centre dot 2H_2O, trans-[ReO(OH)(dmpe)_2](CF_3SO_3)_2, trans-[ReN(Cl)(dmpe)_2]CF_3SO_3 and trans-[ReCl_2(dmpe)_2]ReO_4

摘要

The reaction of trans-[ReO_2(en)_2]Cl with dimethylphosphi-noethane (dmpe) yielded the yellow complex trans-[ReO_2 (dmpe)_2]Cl (1), which, upon reaction with CF3SO3H, yields orange crystals of the oxo-hydroxo complex trans-[ReO (OH)(dmpe)_2](CF_3SO_3)_2 (2). Reaction of trans-[ReNCl_2(PPh_3)_2] with dmpe resulted in orange crystals of trans-[ReN(Cl)(dmpe)2]-CF_3SO_3 (3). Adjustment of the pH of a solution of trans-[ReN(Cl)(dmpe)_2]CF_3SO_3 to 11.7 with NaOH resulted in the formation of yellow crystals of trans-[ReCl_2(dmpe)_2]ReO_4 (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 pi back bonding. The preliminary pK_a determination for the protonation of [ReO_2(dmpe)_2]~+ to form [ReO(OH)(dmpe)_2]~(2+) showed the pK_(a2) to be <1. Crystallographic data: trans-[ReO_2(dmpe)_2]~+: monoclinic space group P2_1/c with a = 11.5299(7) A, b = 15.2397(9) A, c = 15.0230(9) A, beta = 97.7260(10) deg , 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, beta = 101.9360(10) deg , Z = 2; trans-[ReN(Cl) (dmpe)_2~+: orthorhombic space group Pmc2_1 with a = 11.5068(10) A, b = 9.6656(8) A, c = 12.1772(11) A, Z = 2; trans-[Me(Cl)_2(dmpe)_2]~+: monoclinic space group P2_1/c with a = 19.375(3) A, b = 8.6840(12) A, c = 15.910(2)A, beta = 111.270(3) deg, Z = 4. The conformation of the two dmpe ligands in all of the complexes described were lambda delta (eclipsed).