Fig. 2. (A) Synthesis of 3–5. (B) Solid-state structure of 3a and 3b (ellipsoids are set to 50% probability; H atoms are omitted for clarity). Selected distances (Å): 3a: P1–P2 2.0609(7), P2–C1 1.874(19), C1–O1 1.242(2), C1–C2 1.416(3), C2–C3 1.385(3), P1–C4 1.749(2), C4–C5 1.389(3); 3b: P1–P2 2.0657(19), P2–C1 1.861(6), C1–O1 1.220(6), C1–C2 1.454(7), C2–C3 1.376(7), P1–C4 1.762(6), C4–C5 1.391(7), C4–C6 1.500(7).
