The discovery of long-range magnetic order in atomically thin two-dimensional (2D) materials is a new emerging field promising for future applications in ultra-compact low-power spintronics, memory technologies and neuromorphic computing etc. The family of 2D magnets is rapidly expanding and the van der Waals and non-van der Waals chalcogenides of chromium are emerging as a family of materials with air stability and high magnetic transitions temperatures approaching. In this talk, I will present our recent work on the precise synthesis of different crystal phases of chromium sulfides and on the characterizations of their magnetic and electronic properties. The synthesis precision is based on the kinetic control of the nucleation process, which deterministically defines the crystal structure and the material composition. In the case of layered CrS_2, we have demonstrated nucleation-controlled synthesis of either a trigonal prismatic phase or an octahedral phase. The possible mechanisms of crystallization of metastable polymorphs will be discussed and liquid versus vapour based synthetic approaches will be compared.  Ultimately, we demonstrate the use of 2D chromium sulfides in devices.