In this paper we report the synthesis and single-crystal X-ray characterisation of six novel indium(iii) xanthate complexes. These xanthates have been used as an In-source for the synthesis of highly crystalline CuInS2 nanoparticles in conjunction with a Cu(i)-xanthate. In synthesising the nanoparticles we have also demonstrated an ability to control the phase of the material through choice of solvent.