Synthesis and Reactivity of Iridium and Rhodium Silyl Complexes Supported by a Bipyridine Ligand

2009-09-14T00:00:00Z (GMT) by Jennifer L. McBee T. Don Tilley
The rhodium and iridium complexes [(<sup><i>t</i></sup>Bu<sub>2</sub>bpy)<sub>2</sub>M(μ-Cl)]<sub>2</sub> (M = Rh (<b>1</b>), Ir (<b>2</b>)) containing the bidentate <sup><i>t</i></sup>Bu<sub>2</sub>bpy (4,4′-di-<i>tert</i>-butyl-2,2′-bipyridyl) ligand were prepared. Dimeric complexes <b>1</b> and <b>2</b> react with HSiPh<sub>3</sub> to give [(<sup><i>t</i></sup>Bu<sub>2</sub>bpy)MH(SiPh<sub>3</sub>)(μ-Cl)]<sub>2</sub> in good yields (M = Rh (<b>3</b>) 92%, Ir (<b>4</b>) 90%). Addition of P<sup><i>i</i></sup>Pr<sub>3</sub> to <b>3</b> or <b>4</b> gave monomeric crystalline complexes of the type (<sup><i>t</i></sup>Bu<sub>2</sub>bpy)MH(SiPh<sub>3</sub>)Cl(P<sup><i>i</i></sup>Pr<sub>3</sub>) (M = Rh (<b>7</b>) and Ir (<b>8</b>)), which adopt a slightly distorted octahedral coordination geometry with the <sup><i>t</i></sup>Bu<sub>2</sub>bpy ligand occupying sites <i>trans</i> to the hydride and chloride ligands, as determined by X-ray crystallography. Salt metathesis reactions of <b>7</b> and <b>8</b> produced (<sup><i>t</i></sup>Bu<sub>2</sub>bpy)MH(SiPh<sub>3</sub>)(R)P<sup><i>i</i></sup>Pr<sub>3</sub> as monomeric octahedral complexes with the <sup><i>t</i></sup>Bu<sub>2</sub>bpy ligand occupying sites <i>trans</i> to the hydride and R substituents (M = Rh, R = H (<b>11</b>) and M = Ir, R = H (<b>12</b>), Me (<b>14</b>), and Ph (<b>15</b>)). Salt metathesis reactions with <b>3</b> and <b>4</b> also generated the dimeric, dicationic complexes [(<sup><i>t</i></sup>Bu<sub>2</sub>bpy)M(SiPh<sub>3</sub>)(μ-H)]<sub>2</sub>[B(C<sub>6</sub>F<sub>5</sub>)<sub>4</sub>]<sub>2</sub>, where M = Rh (<b>16</b>) or Ir (<b>17</b>). Thermolysis of <b>15</b> at 100 °C in C<sub>6</sub>H<sub>6</sub> for 1 day produced <b>12</b> and Ph<sub>4</sub>Si in 47% yield, and heating <b>15</b> in the presence of 1 equiv of HSiR<sub>3</sub> (R = Ph, Et) also gave <b>12</b>, as well as the Si−C coupled product PhSiR<sub>3</sub> in >95% yield.