<jats:title>Abstract</jats:title><jats:p>A series of iridium tetrahydride complexes [Ir(H)<jats:sub>4</jats:sub>(PSiP‐R)] bearing a tridentate pincer‐type bis(phosphino)silyl ligand ([{2‐(R<jats:sub>2</jats:sub>P)C<jats:sub>6</jats:sub>H<jats:sub>4</jats:sub>}<jats:sub>2</jats:sub>MeSi]<jats:sup>−</jats:sup>, PSiP‐R, R=Cy, <jats:italic>i</jats:italic>Pr, or <jats:italic>t</jats:italic>Bu) were synthesized by the reduction of [IrCl(H)(PSiP‐R)] with Me<jats:sub>4</jats:sub>N<jats:bold>⋅</jats:bold>BH<jats:sub>4</jats:sub> under argon. The same reaction under a nitrogen atmosphere afforded a rare example of thermally stable iridium(III)–dinitrogen complexes, [Ir(H)<jats:sub>2</jats:sub>(N<jats:sub>2</jats:sub>)(PSiP‐R)]. Two isomeric dinitrogen complexes were produced, in which the PSiP ligand coordinated to the iridium center in meridional and facial orientations, respectively. Attempted substitution of the dinitrogen ligand in [Ir(H)<jats:sub>2</jats:sub>(N<jats:sub>2</jats:sub>)(PSiP‐Cy)] with PMe<jats:sub>3</jats:sub> required heating at 150 °C to give the expected [Ir(H)<jats:sub>2</jats:sub>(PMe<jats:sub>3</jats:sub>)(PSiP‐Cy)] and a trigonal bipyramidal iridium(I)–dinitrogen complex, [Ir(N<jats:sub>2</jats:sub>)(PMe<jats:sub>3</jats:sub>)(PSiP‐Cy)]. The reaction of [Ir(H)<jats:sub>4</jats:sub>(PSiP‐Cy)] with three equivalents of 2‐norbornene (nbe) in benzene afforded [Ir<jats:sup>I</jats:sup>(nbe)(PSiP‐Cy)] in a high yield, while a similar reaction of [Ir(H)<jats:sub>4</jats:sub>(PSiP‐R)] with an excess of 3,3‐dimethylbutene (tbe) in benzene gave the CH bond activation product, [Ir<jats:sup>III</jats:sup>(H)(Ph)(PSiP‐R)], in high yield. The oxidative addition of benzene is reversible; heating [Ir<jats:sup>III</jats:sup>(H)(Ph)(PSiP‐Cy)] in the presence of PPh<jats:sub>3</jats:sub> in benzene resulted in reductive elimination of benzene, coordination of PPh<jats:sub>3</jats:sub>, and activation of the CH bond of one aromatic ring in PPh<jats:sub>3</jats:sub>. [Ir<jats:sup>III</jats:sup>(H)(Ph)(PSiP‐R)] catalyzed a direct borylation reaction of the benzene CH bond with bis(pinacolato)diboron. Molecular structures of most of the new complexes in this study were determined by a single‐crystal X‐ray analysis.</jats:p>