Synthesis and Reactivity of Ruthenium Hydride Complexes Containing a Tripodal Aminophosphine Ligand

Ru
complexes containing a tris­(aminophosphine) ligand (N­(NP)3) have been prepared and their reactivity examined. The complex
[(N­((CH2)2NHPiPr2)2(κ2N,P-((CH2)2NHPiPr2))­RuCl]­[Cl] (1) is transformed to [(N­((CH2)2NHPiPr2)2((CH2)2NPHiPr2))­RuCl]­Cl
(2) on standing in solution. Deprotonation of the phosphonium
center in 2 followed by anion exchange generates the
Ru hydride complex [(N­((CH2)2NHPiPr2)­((CH2)2NPiPr2)­(CH2CHNHPiPr2))­RuH]­[BPh4] (3), which can bind acetonitrile to give [(N­((CH2)2NHPiPr2)2((CH2)2NPiPr2))­Ru­(CH3CN)]­[BPh4] (5). Protonation of 3 and 5 with either a 1 M solution of HCl in
diethyl ether or NEt3HCl yields [(N­((CH2)2NHPiPr2)2((CH2)2NPHiPr2))­RuCl]­[BPh4] (6). Reaction
of 3 with H2 gives the Ru hydride complex
[(N­((CH2)2NHPiPr2)2(κ2N,P((CH2)2NHPiPr2))­RuH]­[BPh4] (8), which is deprotonated with KN­(SiMe3)2 to give [(N­((CH2)2NHPiPr2)2)­((CH2)2NPiPr2)­RuH] (9). This latter
species reacts with H2 to generate [(N­((CH2)2NHPiPr2)3)­Ru­(H)2] (10). The hydride species 3 is
also shown to react with CO2, N2O, phenylacetylene,
and 1-pentyne to give [(N­((CH2)2NHPiPr2)2((CH2)2NP­(CO2)iPr2))­Ru]­[BPh4] (11), [(N­((CH2)2NHPiPr2)2((CH2)2NP­(O)iPr2))­Ru]­[BPh4] (12),
and [(N­((CH2)2NHPiPr2)2((CH2)2NP­(R)iPr2))­Ru]­[BPh4] (R = C8H6 (13), C5H10 (14)),
in which the substrate is bound to P and the metal center. In contrast, 9 does not react with N2O and alkyne but reacts
with CO2 to give CO2 insertion into the N–P
bond, yielding (N­((CH2)2NHPiPr2)2((CH2)2N­(CO2)­PiPr2)­RuH (15).