Complex sentence: Nabokov's son Dmitri Nabokov and wife Vera Nabokov became his literary executors but could not bring themselves to destroy Nabokov's final work, and so it was placed in a Swiss Bank vault where it has remained since his death.
Split into simpler sentences: Nabokov's son Dmitri Nabokov and wife Vera Nabokov became his literary executors. But neither Dmitri nor Vera could bring themselves to destroy Nabokov's final work, and so it was placed in a Swiss Bank vault where it has remained since his death.