A neutron can decay into a proton, an electron, and neutrino. Could an antiproton, a positron, and a neutrino combine into a neutron? Could this be where much of the "missing" antimatter is?
Assuming that by "negatron" you mean a anti-proton, then no. It violated the conservation of baryon number (for aproton $B = -1$ and for a neutron $B = 1$) and in any case, free neutrons are unstable--it's not just that they can decay, they will decay.
Worse still, neutrons do interact with light, albeit with a low corss-section because they are composites of charge quarks and gluons.