NOVELTY - Preparation of a chalcopyrite-type compound comprises reacting group III-containing compound with group I-containing compound, in the presence of coordinating solvent(s), to obtain a metal-containing compound; and reacting the metal-containing compound with a transition metal-containing compound, in the presence of coordinating solvent(s), and/or another coordinating solvent(s), to obtain the chalcopyrite-type compound.    USE - The process is used for preparing chalcopyrite-type compound for use in the field of electrochemistry. It is used for the preparation of a nanocrystalline compound for use in a solar cell, in the field of optoelectronic, or in the preparation of a photodiode, transistor, sensor, laser diode, or digital light projector (claimed).    ADVANTAGE - The process enables preparation of chalcopyrite-type compounds, which are highly crystalline, easily and at low costs. It can be carried out without the use of costly reagents. It avoids carrying steps under toxic conditions such as hydrogen sulfide atmosphere. It permits high purity compounds to be obtained. It can be carried out in anhydrous conditions to reduce the risk of formation of metal oxides. It is environment friendly and can be carried out rapidly.    DETAILED DESCRIPTION - Preparation of a chalcopyrite-type compound of formula M3M1A2 comprises reacting a compound of formula M1(X1)3 with a compound of formula (M2)2A, in the presence of coordinating solvent(s), to obtain a compound of formula M2M1A2; reacting the compound of formula M2M1A2 with a compound of formula M3X2, in the presence of coordinating solvent(s), and/or another coordinating solvent(s), to obtain the compound of formula M3M1A2.    M1=B3+, Al3+, Ga3+, In3+, Tl3+, Fe3+, or Au3+;    M2=Li+, Na+, K+, Cs+, (T1)3Si-, or N(T2)4+;    T1=1-6C alkyl;    T2=H or 1-6C alkyl;    M3=Cu+, Ag+, Li+, Na+, K+, Cs+, Rb+, Fr+, Au+, or Hg+;    A=S, Se, or Te; and    X1 and X2=CI-, Br-, I-, F-, CH3COO-, NO3-, OCN-, SCN-, or CN-.    INDEPENDENT CLAIMS are also included for:    (1) a process for preparing a compound of formula M4A, comprising reacting a compound of formula M4X2 with a compound of formula (M2)2A, in the presence of coordinating solvent(s);    (2) use of a process for the preparation of a nanocrystalline compound for use in a solar cell, in the field of optoelectronic, or in the preparation of a photodiode, transistor, sensor, laser diode, or digital light projector;    (3) a composition comprising the nanocrystalline compound and a binder;    (4) use of the composition in the manufacture of optoelectronic device, photoluminescent device, or a wireless communication device;    (5) a method for preparing a solar cell, photodiode, transistor, sensor, laser diode or digital projector comprising using the composition as a component or precursor in the preparation;    (6) a composition comprising indium chloride (InCl3) and a coordinating solvent;    (7) use of the composition as an anhydrous source of InCl3;    (8) use of coordinating solvent for preparing InCl3-based composition, or for solubilizing and stabilizing InCl3;    (9) a method for preparing InCl3-based composition comprising dissolving and stabilizing InCl3 in a coordinating solvent; and    (10) a compound prepared by the inventive process, where two different compounds of formula M1(X1)3 are reacted with the compound of formula (M2)2A.    M2, A=have meanings as defined;    M4=Cd2+, Co2+, Ni2+, Zn2+, Hg2+, Mg2+, Mn2+, Fe2+, or Pb2+.    DESCRIPTION OF DRAWING(S) - The figure shows a X-ray diffraction pattern of a CuInS2 sample obtained by the inventive process, where sample was annealed at 500degreesC, under a vacuum of 100 mTorr, for 2 hours.