Coordination Chemistry of H2 and N2 in Aqueous Solution. Reactivity and Mechanistic Studies Using trans-FeII(P2)2X2-Type Complexes (P2 = a Chelating, Water-Solubilizing Phosphine)

John D GILBERTSON; Nathaniel K SZYMCZAK; Justin L CROSSLAND; Warren K MILLER; David K LYON; Bruce M FOXMAN; Joclyn DAVIS; David R TYLER

doi:10.1021/ic061570o

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Coordination Chemistry of H2 and N2 in Aqueous Solution. Reactivity and Mechanistic Studies Using trans-FeII(P2)2X2-Type Complexes (P2 = a Chelating, Water-Solubilizing Phosphine)

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Coordination Chemistry of H2 and N2 in Aqueous Solution. Reactivity and Mechanistic Studies Using trans-FeII(P2)2X2-Type Complexes (P2 = a Chelating, Water-Solubilizing Phosphine)

John D GILBERTSON, Nathaniel K SZYMCZAK, Justin L CROSSLAND, Warren K MILLER, David K LYON, Bruce M FOXMAN, Joclyn DAVIS and David R TYLER

Inorganic chemistry, Vol.46(4), pp.1205-1214

02/19/2007

DOI: https://doi.org/10.1021/ic061570o

Abstract

The reactions of the trans-Fe(DMeOPrPE)2Cl2 complex (I; DMeOPrPE = 1,2-bis(bis(methoxypropyl)phosphino)ethane) and its derivatives were studied in aqueous and nonaqueous solvents with a particular emphasis on the binding and activation of H2 and N2. The results show there are distinct differences in the reaction pathways between aqueous and nonaqueous solvents. In water, I immediately reacts to form trans-Fe(DMeOPrPE)2(H2O)Cl+. Subsequent reaction with H2 or N2 yields trans-Fe(DMeOPrPE)2(X2)Cl+ (X2H2 or N2). In the case of H2, further reactivity occurs to ultimately give the trans-Fe(DMeOPrPE)2(H2)H+ product (III). The pathway for the reaction I → III was spectroscopically examined: following the initial loss of chloride and replacement with H2, heterolysis of the H2 ligand occurs to form Fe(DMeOPrPE)2(H)Cl; substitution of the remaining chloride ligand by another H2 molecule then occurs to produce trans-Fe(DMeOPrPE)2(H2)H+. In the absence of H2 or N2, trans-Fe(DMeOPrPE)2(H2O)Cl+ slowly reacts in water to form Fe(DMeOPrPE)32+, II. Experiments showed that this species forms by reaction of free DMeOPrPE ligand with trans-Fe(DMeOPrPE)2(H2O)Cl+, where the free DMeOPrPE ligand comes from dissociation from the trans-Fe(DMeOPrPE)2(H2O)Cl+ complex. In nonaqueous solvents, the chloride ligand in I is not labile, and a reaction with H2 only occurs if a chloride abstracting reagent is present. Complex III is a useful synthon for the formation of other water-soluble metal hydrides. For example, the trans-[Fe(DMeOPrPE)2H(N2)]+ complex was generated in H2O by substitution of N2 for the H2 ligand in III. The trans-Fe(DHBuPE)2HCl complex (DHBuPE = 1,2-bis(bis(hydroxybutyl)phosphino)ethane, another water-solubilizing phosphine) was shown to be a viable absorbent for the separation of N2 from CH4 in a pressure swing scheme. X-ray crystallographic analysis of II is the first crystal structure report of a homoleptic tris chelate of FeII containing bidentate phosphine ligands. The structure reveals severe steric crowding at the Fe center.

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Title: Coordination Chemistry of H2 and N2 in Aqueous Solution. Reactivity and Mechanistic Studies Using trans-FeII(P2)2X2-Type Complexes (P2 = a Chelating, Water-Solubilizing Phosphine)
Creators: John D GILBERTSON - Department of Chemistry, University of Oregon, Eugene, Oregon 97403, Bend Research, Inc.,64550 Research Road, Bend, Oregon 97701, and Chemistry Department, Brandeis University MS015, 415 South Street, Waltham, Massachusetts 02454
Nathaniel K SZYMCZAK - Department of Chemistry, University of Oregon, Eugene, Oregon 97403, Bend Research, Inc.,64550 Research Road, Bend, Oregon 97701, and Chemistry Department, Brandeis University MS015, 415 South Street, Waltham, Massachusetts 02454
Justin L CROSSLAND - Department of Chemistry, University of Oregon, Eugene, Oregon 97403, Bend Research, Inc.,64550 Research Road, Bend, Oregon 97701, and Chemistry Department, Brandeis University MS015, 415 South Street, Waltham, Massachusetts 02454
Warren K MILLER - Department of Chemistry, University of Oregon, Eugene, Oregon 97403, Bend Research, Inc.,64550 Research Road, Bend, Oregon 97701, and Chemistry Department, Brandeis University MS015, 415 South Street, Waltham, Massachusetts 02454
David K LYON - Department of Chemistry, University of Oregon, Eugene, Oregon 97403, Bend Research, Inc.,64550 Research Road, Bend, Oregon 97701, and Chemistry Department, Brandeis University MS015, 415 South Street, Waltham, Massachusetts 02454
Bruce M FOXMAN - Department of Chemistry, University of Oregon, Eugene, Oregon 97403, Bend Research, Inc.,64550 Research Road, Bend, Oregon 97701, and Chemistry Department, Brandeis University MS015, 415 South Street, Waltham, Massachusetts 02454
Joclyn DAVIS - Department of Chemistry, University of Oregon, Eugene, Oregon 97403, Bend Research, Inc.,64550 Research Road, Bend, Oregon 97701, and Chemistry Department, Brandeis University MS015, 415 South Street, Waltham, Massachusetts 02454
David R TYLER - Department of Chemistry, University of Oregon, Eugene, Oregon 97403, Bend Research, Inc.,64550 Research Road, Bend, Oregon 97701, and Chemistry Department, Brandeis University MS015, 415 South Street, Waltham, Massachusetts 02454
Publication Details: Inorganic chemistry, Vol.46(4), pp.1205-1214
Publisher: American Chemical Society
Identifiers: 9923989470201921
Academic Unit: Department of Chemistry
Language: English
Resource Type: Journal article

Coordination Chemistry of H2 and N2 in Aqueous Solution. Reactivity and Mechanistic Studies Using trans-FeII(P2)2X2-Type Complexes (P2 = a Chelating, Water-Solubilizing Phosphine)

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