Thermal ellipsoid drawing (50% probability) of W(O)(B(C6F5)3)(CH-t-Bu)(OHMT)(Me2Pyr) (5.B(C6F5)3). Hydrogen atoms have been omitted for clarity. Selected bond distances (Å) and angles (°): W1–C1 = 1.868(2), W1–O2 = 1.759(2), W1–O1 = 1.860(2), W1–N1 = 1.968(2), B1–O2 = 1.571(3), W1–O1–C21 = 150.9(1), W1–C1–C2 = 155.4(2).