The electrostatic complexation between model negatively charged silica nanoparticles (NPs) with radius R~10 nm and chitosan, a natural polyelectrolyte bearing positive charges with a semi-rigid backbone of persistence length of Lp~9 nm, was studied by a combination of SANS, SAXS, light scattering, and cryo-TEM. In this system, corresponding to Lp/R~1, we observe the formation of (i) randomly branched complexes in the presence of an excess of chitosan chains and (ii) well-defined single-strand nanorods in 10 the presence of an excess of nanoparticles. We also observe no formation of nanorods for NPs with poly-L-lysine, a flexible polyelectrolyte, corresponding to Lp/R~0.1, suggesting a key role played by this ratio Lp/R. In the intermediate range of nanoparticles concentrations, we observe an associative phase separation (complex coacervation) leading to more compact complexes in both supernatant and coacervate phases. This method might open the door to a greater degree of control of nanoparticles self-15 assembly into larger nanostructures, through molecular structural parameters like Lp/R, combined with polyelectrolytes/nanoparticles ratio.