Paramagnetic Rh(III) complexes from reactions of phosphines with hydride-bridged and nonbridged rhodium phthalocyanine dimers: Metal-to-ligand charge transfer induced by phosphines
- Argonne National Lab., IL (United States)
The paramagnetic rhodium phthalocyanine complex (RPc)(PMe{sub 3}){sub 2}Rh (4) (RPc = dianion of 1,4,8,11,15,18,22,25-octa-n-pentylphthalocyanine) has been prepared by the reaction of trimethylphosphine (PMe{sub 3}) with hydride-bridged and nonbridged rhodium phthalocyanine dimers. The reaction of the {mu}-hydrido complex (RPcH)Rh({mu}-H)Rh(RPc) (5) (RPcH = RPc with one of its meso nitrogens protonated) with PMe{sub 3} at {minus}10 C produces (RPc)(PMe{sub 3})RhH (6), which further reacts with PMe{sub 3} to produce 4 and H{sub 2} at higher temperatures. If the solution of 6 is allowed to warm in the absence of free PMe{sub 3}, H{sub 2} is also liberated and 6 is converted to an equal number of moles of 4 and [(RPc)Rh]{sub 2}(PMe{sub 3}) (7). In contrast, the reaction of 5 with pyridine (py) produces (RPc)(py)-RhH (11), which does not react with additional pyridine. Alternatively, 4 is generated by the reaction of the Rh-Rh bonded dimer [(RPc)Rh]{sub 2} (1) with PMe{sub 3}. In this reaction, the formation of 7 as an intermediate may be shown by the titration of 1 with PMe{sub 3}. Complex 1 reacts with 4 to produce (RPc)Rh{sup {minus}} (10) and (RPc)(PMe{sub 3}){sub 2}-Rh{sup +} (9). A redox exchange between 4 and 9 ensues. The cobalt analogue of 4, i.e., (RPc)(PMe{sub 3}){sub 2}Co (12), was generated reversibly by the reaction of (RPc)Co (13) with PMe{sub 3} at low temperatures. The {sup 1}H NMR and the ESR spectra of 4, 12, and 13 indicate that while 13 is a metal-centered radical, 4 and 12 are best described as ligand-centered radicals.
- Research Organization:
- Argonne National Lab. (ANL), Argonne, IL (United States)
- Sponsoring Organization:
- USDOE, Washington, DC (United States)
- DOE Contract Number:
- W-31109-ENG-38
- OSTI ID:
- 316206
- Journal Information:
- Inorganic Chemistry, Vol. 37, Issue 22; Other Information: PBD: 2 Nov 1998
- Country of Publication:
- United States
- Language:
- English
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