12103-40-1Relevant articles and documents
Intra- and inter-ion-pair protonic - Hydridic bonding in polyhydridobis(phosphine)rhenates
Abdur-Rashid,Lough,Morris
, p. 964 - 976 (2001)
The hexahydridobis(phosphine)rhenate anions, [ReH6(PR3)2]- (PR3 = PCy3 ,P-i-Pr3, PPh3, PMe3) were generated by potassium hydride deprotonation of the neutral heptahydride conjugate acids (ReH7(PR3)2), isolated as their [K(18-crown-6)]+ and [K(1,10-diaza-18-crown-6)]+ salts, and characterized by NMR and IR spectroscopy and elemental analyses. Structures from single crystal X-ray diffraction were obtained for the [K(1,10-diaza-18-crown-6)]+ salts and these indicate the presence of short protonic - hydridic bonds involving the hydrides of the anions and the proton donor NH moieties of the cations. The structure of [K(1,10-diaza-18-crown-6)][ReH6(P-i-Pr3)2] adopts a one-dimensional zigzag chain with alternating cations and anions connected and held together by inter-ion N-H···Hx-Re interactions (x = 1 or 2). Short distances between the NH protons of the cations and hydrides of the anion ranging from 1.6 to 1.9 A are estimated for this complex. A different kind of chain structure is observed for [K(1,10-diaza-18-crown-6)][ ReH6(PMe3)2] in which the combined effects of inter-ion protonic - hydridic bonding (N-H···Hx-Re) and inter-ion electrostatic interactions (ReHx-···K+ ···Hx-Re), result in one-dimensional networks of alternating cations and anions, with the metals and hydrides occupying the interior and the organic moieties of the phosphine ligands and crown ether lining the exterior of cylindrical supramolecular assemblies. A combination of intra- and inter-ion protonic-hydridic and intra-ion-pair electrostatic interactions in [K(1,10-diaza-18-crown-6)][ReH6(PPh3)2] result in the formation of discrete two-dimensional {[K(1,10-diaza-18-crown-6)][ReH6(PPh3)2]} 4 tetramers. The PCy3 salt is disordered but appears to consist of isolated 1:1 ion pairs containing strong intra-ion-pair NH···HRe bonding. The solid-state IR spectra of the [K(1,10-diaza-18-crown-6)]+ salts show low-frequency shifts for the NH bands relative to [K(1,10-diaza-18-crown-6)][BPh4], and perturbed Re-H bands relative to those in the [K(18-crown-6)]+ salts. The magnitude of δvnNH is related to the basicity of the anion as indicated by the pKαTHF of the conjugate acid form (ReH7(PR3)2), which increases as PPh3 3 3 3. Solution 1H NMR, NOE, and T1 relaxation measurements of [K(1,10-diaza-18-crown-6)][ReH6(PPh3)2] indicate that these interactions also persist in toluene solutions of this compound.
Reactions of alkyl isocyanides with polyhydride complexes of rhenium and with binuclear dirhenium complexes containing quadruple or triple bonds: Nonreductive and reductive cleavage of Re-Re multiple bonds to afford mononuclear isocyanide complexes of rhenium(I) and rhenium(III)
Allison, Joe D.,Wood, Thomas E.,Wild, Robert E.,Walton, Richard A.
, p. 3540 - 3546 (2008/10/08)
Treatment of the dinuclear quadruply bonded complexes Re2(O2CR)4Cl2 (R = CH3 or C6H5) with alkyl isocyanides (RNC; R = CMe3 or C6H11) affords solutions from which salts of the [Re(CNR)6]+ cations can be isolated in good yield. While [Re(CNR)6]+ is inert to substitution by monodentate tertiary phosphines, routes to species of the type [Re(CNR)4(PR3)2]+ are afforded by (a) the reductive cleavage of the triply bonded complexes Re2Cl4(PR3)4 by RNC ligands or (b) the reductive elimination of H2 from the polyhydride complexes ReH7(PR3)2 and ReH5(PR3)2L in the presence of an excess of RNC. In contrast to the preceding reductive-cleavage reductions, the halide-rich salts (n-Bu4N)2Re2X8 (X = Cl or Br) react with tert-butyl isocyanide to give mononuclear seven-coordinate rhenium(III) species [Re(CNCMe3)5X2]+, which have been isolated as their PF6- salts. The mixed isocyanide-halide-phosphine complexes of rhenium(III) [Re(CNCMe3)4(PEtPh2)Cl2]PF 6 and [Re(CNCMe3)3(dppe)Cl2]PF6 (dppe = Ph2PCH2CH2PPh2) are likewise prepared by isocyanide cleavage of quadruply bonded Re2Cl6(PEtPh2)2 and dimeric Re2Cl6(dppe)2 (the latter containing Re(μ-Cl)2Re bridges but no Re-Re bond). The spectroscopic and electrochemical properties of these complexes are reported, and the significance of the cleavage reactions by π-acceptor ligands (such as RNC) is discussed in the context of their constituting an important synthetic route to mononuclear transition-metal complexes.
