ORTEP diagram of 4a (thermal ellipsoids at the 50% probability level). Hydrogen atoms have been omitted except for the hydrides bound to rhodium. Selected bond lengths (Å): Rh1–P1 = 2.2763(8), Rh1–P2 = 2.3456(8), Rh1–H1A = 1.48(3), Rh1–H1B = 1.49(3), and Rh1–Si1 = 2.3126(8). Selected bond angles (deg): P1–Rh1–Si1 = 115.52(3), P2–Rh1–Si1 = 129.64(3), H1A–Rh1–Si1 = 53(1), and H1B–Rh1–Si1 = 63(1).