SYNTHESIS AND CHARACTERIZATION OF THE ELECTRON-RICH IRON HYDRIDE HFE(CO)2(P(OPH)3)2- AND ITS LIGAND-BASED REDOX SUBSTITUTION WITH THIOLATES
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The bis(phoephite) anionic hydride [Et4N+][HFe(CO)2(P(OPh)3)2] has been synthesized by deprotonation of H2Fe(CO)2(P(OPh)3)2 with [Et4N+][OH]. The [Et4N+][HFe(CO)2(P(OPh)3)2] salt was characterized by X-ray diffraction, crystallizing in the monoclinic space group Cc (No. 9) with a = 15.821 (4) , b = 15.168 (3) , c = 19.125 (6) , = 111.05(2), V = 4283 (2) 3, and Z = 4. In the solid state the hydride anion has a distorted-trigonal-bipyramidal geometry in which the hydride ligand occupies an axial position with an Fe-H bond distance of 1.47 . One triphenyl phosphite ligand is cis to the hydride and has an Fe-Peq bond distance of 2.076 (1) , the other is trans with Fe-Pax= 2.083 (1) , and Peq-Fe-Pax is 103.2 (1). Analysis of the v(CO) infrared and 1H NMR results imply that in solution the isomer in which both phosphite ligands are cis to the hydride predominates as the ground-state structure. The alkali-metal cations Na+ and K+ form contact ion pairs with [HFe(CO)2(P(OPh)3)2], specifically interacting with the carbonyl oxygens of both CO ligands simultaneously. The [HFe(CO)2(P(OPh)3)2] anion reacts with PhSSPh to yield [Et4N+][(PhS)Fe(CO)2(P(OPh)3)2] but is unreactive with MeSSMe and t-BuSS-t-Bu. 1992, American Chemical Society. All rights reserved.