10.1021/ic061570o.s003
John D. Gilbertson
John D.
Gilbertson
Nathaniel K. Szymczak
Nathaniel K.
Szymczak
Justin L. Crossland
Justin L.
Crossland
Warren K. Miller
Warren K.
Miller
David K. Lyon
David K.
Lyon
Bruce M. Foxman
Bruce M.
Foxman
Joclyn Davis
Joclyn
Davis
David R. Tyler
David R.
Tyler
Coordination Chemistry of H<sub>2</sub> and N<sub>2</sub> in Aqueous Solution. Reactivity
and Mechanistic Studies Using <i>trans</i>-Fe<sup>II</sup>(P<sub>2</sub>)<sub>2</sub>X<sub>2</sub>-Type Complexes (P<sub>2</sub> = a
Chelating, Water-Solubilizing Phosphine)
American Chemical Society
2007
2O
H 2 molecule
N 2
chloride ligand
pressure swing scheme
crystal structure report
homoleptic tris chelate
H 2
H 2 ligand
Fe
nonaqueous solvents
CH
bidentate phosphine ligands
DMeOPrPE ligand
III
II
2007-02-19 00:00:00
Dataset
https://acs.figshare.com/articles/dataset/Coordination_Chemistry_of_H_sub_2_sub_and_N_sub_2_sub_in_Aqueous_Solution_Reactivity_and_Mechanistic_Studies_Using_i_trans_i_Fe_sup_II_sup_P_sub_2_sub_sub_2_sub_X_sub_2_sub_Type_Complexes_P_sub_2_sub_a_Chelating_Water_Solubilizing_Phosphine_/3025537
The reactions of the <i>trans</i>-Fe(DMeOPrPE)<sub>2</sub>Cl<sub>2</sub> complex (<b>I</b>; 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 H<sub>2</sub> and N<sub>2</sub>. The results show there are distinct differences in the reaction pathways
between aqueous and nonaqueous solvents. In water, <b>I</b> immediately reacts to form <i>trans</i>-Fe(DMeOPrPE)<sub>2</sub>(H<sub>2</sub>O)Cl<sup>+</sup>. Subsequent reaction with H<sub>2</sub> or N<sub>2</sub> yields <i>trans</i>-Fe(DMeOPrPE)<sub>2</sub>(X<sub>2</sub>)Cl<sup>+</sup> (X<sub>2</sub>H<sub>2</sub> or N<sub>2</sub>). In the case of H<sub>2</sub>,
further reactivity occurs to ultimately give the <i>trans</i>-Fe(DMeOPrPE)<sub>2</sub>(H<sub>2</sub>)H<sup>+</sup> product (<b>III</b>). The pathway for the reaction
<b>I</b> → <b>III</b> was spectroscopically examined: following the initial loss of chloride and replacement with H<sub>2</sub>, heterolysis
of the H<sub>2</sub> ligand occurs to form Fe(DMeOPrPE)<sub>2</sub>(H)Cl; substitution of the remaining chloride ligand by another H<sub>2</sub>
molecule then occurs to produce <i>trans</i>-Fe(DMeOPrPE)<sub>2</sub>(H<sub>2</sub>)H<sup>+</sup>. In the absence of H<sub>2</sub> or N<sub>2</sub>, <i>trans</i>-Fe(DMeOPrPE)<sub>2</sub>(H<sub>2</sub>O)Cl<sup>+</sup> slowly reacts in water to form Fe(DMeOPrPE)<sub>3</sub><sup>2+</sup>, <b>II</b>. Experiments showed that this species forms by
reaction of free DMeOPrPE ligand with <i>trans</i>-Fe(DMeOPrPE)<sub>2</sub>(H<sub>2</sub>O)Cl<sup>+</sup>, where the free DMeOPrPE ligand comes
from dissociation from the <i>trans</i>-Fe(DMeOPrPE)<sub>2</sub>(H<sub>2</sub>O)Cl<sup>+</sup> complex. In nonaqueous solvents, the chloride ligand in
<b>I</b> is not labile, and a reaction with H<sub>2</sub> only occurs if a chloride abstracting reagent is present. Complex <b>III</b> is a useful
synthon for the formation of other water-soluble metal hydrides. For example, the <i>trans</i>-[Fe(DMeOPrPE)<sub>2</sub>H(N<sub>2</sub>)]<sup>+</sup>
complex was generated in H<sub>2</sub>O by substitution of N<sub>2</sub> for the H<sub>2</sub> ligand in <b>III</b>. The <i>trans</i>-Fe(DHBuPE)<sub>2</sub>HCl complex
(DHBuPE = 1,2-bis(bis(hydroxybutyl)phosphino)ethane, another water-solubilizing phosphine) was shown to be a
viable absorbent for the separation of N<sub>2</sub> from CH<sub>4</sub> in a pressure swing scheme. X-ray crystallographic analysis of
<b>II</b> is the first crystal structure report of a homoleptic tris chelate of Fe<sup>II</sup> containing bidentate phosphine ligands. The
structure reveals severe steric crowding at the Fe center.