Neither was Einstein mathematically gifted, nor did he make meaningful contributions to physics in the last three decades of his life.
Einstein was neither mathematically gifted, and he did not make meaningful contributions to physics in the last three decades of his life.
Neither was Einstein mathematically gifted, nor did he make meaningful contributions to physics in the last three decades of his life.
Einstein was neither mathematically gifted, and he did not make meaningful contributions to physics in the last three decades of his life.
The word "neither" is always paired with "nor" as a unit. It cannot be used with an alternate second half ("neither ... and not").