In semiconductors, defects and dopants house localized electrons where the spin degree of freedom can be initialized and coherently controlled with a combination of optical and microwave signals. We show that semiconductor spin-qubits can be embedded in commercial devices where their optical and spin properties can be enhanced by controlling both their electronic and nuclear-spin environment. Organometallic molecules provide an analogous platform for localized, coherent quantum states where both the qubit and its environment can be atomically engineered via chemical synthesis. We present optical addressability and coherent microwave control of the electron-spin ground-state of organometallic molecules containing a central chromium ion. The spin-optical interface of these molecular qubits can be tuned by modifying the structure and symmetry of the ligand field, and its host environment can be used to protect the qubit from magnetic field noise by inducing noise-insensitive clock transitions.