Transition metal–carbon bonds. Part 52. Large ring and cyclometallated complexes formed from Bu<sup>t</sup><sub>2</sub>PCH<sub>2</sub>CH<sub>2</sub>CHRCH<sub>2</sub>CH<sub>2</sub>PBu<sup>t</sup><sub>2</sub>(R  H or Me) and IrCl<sub>3</sub>, or [Ir<sub>2</sub>Cl<sub>4</sub>(cyclo-octene)<sub>4</sub>] : crystal structures of the cyclometallated hydride, [IrHCl(Bu<sup>t</sup><sub>2</sub>PCH<sub>2</sub>CH<sub>2</sub>CHCH<sub>2</sub>CH<sub>2</sub>PBu<sup>t</sup><sub>2</sub>)], and the carbene complex [IrCl(Bu<sup>t</sup><sub>2</sub>PCH<sub>2</sub>CH<sub>2</sub>CCH<sub>2</sub>CH<sub>2</sub>PBu<sup>t</sup><sub>2</sub>)]