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)₂NHP<i>i</i>Pr₂)₂(κ²<i>N</i>,<i>P</i>-((CH₂)₂NHP<i>i</i>Pr₂))­RuCl]­[Cl] (<b>1</b>) is transformed to [(N­((CH₂)₂NHP<i>i</i>Pr₂)₂((CH₂)₂NPH<i>i</i>Pr₂))­RuCl]­Cl (<b>2</b>) on standing in solution. Deprotonation of the phosphonium center in <b>2</b> followed by anion exchange generates the Ru hydride complex [(N­((CH₂)₂NHP<i>i</i>Pr₂)­((CH₂)₂NP<i>i</i>Pr₂)­(CH₂CHNHP<i>i</i>Pr₂))­RuH]­[BPh₄] (<b>3</b>), which can bind acetonitrile to give [(N­((CH₂)₂NHP<i>i</i>Pr₂)₂((CH₂)₂NP<i>i</i>Pr₂))­Ru­(CH₃CN)]­[BPh₄] (<b>5</b>). Protonation of <b>3</b> and <b>5</b> with either a 1 M solution of HCl in diethyl ether or NEt₃HCl yields [(N­((CH₂)₂NHPiPr₂)₂((CH₂)₂NPHiPr₂))­RuCl]­[BPh₄] (<b>6</b>). Reaction of <b>3</b> with H₂ gives the Ru hydride complex [(N­((CH₂)₂NHP<i>i</i>Pr₂)₂(κ²<i>N</i>,<i>P</i>((CH₂)₂NHP<i>i</i>Pr₂))­RuH]­[BPh₄] (<b>8</b>), which is deprotonated with KN­(SiMe₃)₂ to give [(N­((CH₂)₂NHP<i>i</i>Pr₂)₂)­((CH₂)₂NP<i>i</i>Pr₂)­RuH] (<b>9</b>). This latter species reacts with H₂ to generate [(N­((CH₂)₂NHP<i>i</i>Pr₂)₃)­Ru­(H)₂] (<b>10</b>). The hydride species <b>3</b> is also shown to react with CO₂, N₂O, phenylacetylene, and 1-pentyne to give [(N­((CH₂)₂NHP<i>i</i>Pr₂)₂((CH₂)₂NP­(CO₂)<i>i</i>Pr₂))­Ru]­[BPh₄] (<b>11</b>), [(N­((CH₂)₂NHP<i>i</i>Pr₂)₂((CH₂)₂NP­(O)<i>i</i>Pr₂))­Ru]­[BPh₄] (<b>12</b>), and [(N­((CH₂)₂NHP<i>i</i>Pr₂)₂((CH₂)₂NP­(R)<i>i</i>Pr₂))­Ru]­[BPh₄] (R = C₈H₆ (<b>13</b>), C₅H₁₀ (<b>14</b>)), in which the substrate is bound to P and the metal center. In contrast, <b>9</b> does not react with N₂O and alkyne but reacts with CO₂ to give CO₂ insertion into the N–P bond, yielding (N­((CH₂)₂NHP<i>i</i>Pr₂)₂((CH₂)₂N­(CO₂)­P<i>i</i>Pr₂)­RuH (<b>15</b>)