PROPERTIES AND X-RAY STRUCTURE OF PPN+[CIS-HFE(CO)3P(OPH)3]- - AN UNEXPECTED STRUCTURAL ISOMER
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The preparation of [PPN] [HFe(CO)3P(OPh)3] (1) has been carried out by using an alcoholic hydroxide reaction with Fe-(CO)4P(OPh)3; the same synthesis was reported earlier for trans-HFe(CO)3PR3- salts. After spectral and chemical differences were observed between the anion of 1 and all other HFe(CO)3PR3- anions, which have been shown to exist in a trans configuration of H and PR3(TBP geometry), an X-ray structural determination was performed. 1 crystallizes in the triclinic system, space group P, with cell parameters a = 10.491 (3) , b = 13.963 (4) , c = 18.687 (6) , a = 108.19 (2), = 105.47 (2), = 93.16 (2), V = 2478 (1) 3, and Z=2. The hydride ligand was located in the axial position of a distorted trigonal bypyramid, but curiously the P(OPh)3ligand is in the equatorial plane, cis to the hydride. Unique properties of 1 include its air stability and its rigidity as the cis isomer. The spectral properties of 1 including ion pairing and isotopic H/D exchange effects were examined. In contrast to other anion trigonal-bipyramidal complexes that show equatorial CONa+interaction, an axial CONa+site interaction was observed for 1. Hydrogen/deuterium substitution in this anion revealed a large v(MH) to v(CO) coupling to the trans carbonyl group. 1987, American Chemical Society. All rights reserved.