NEW ORGANOSOLS OF CUS, CDS, ZNS, HGS, NIS, AND MIXED METAL SULFIDES IN N,N-DIMETHYLFORMAMIDE AND DIMETHYL-SULFOXIDE - PREPARATION, CHARACTERIZATION, AND PHYSICAL-PROPERTIES

Organosols of transition metal sulfides such as CuS, CdS, Zns, HgS, and NIS in NN-dimethylformamide (DMF) and dimethyl sulfoxide (DMSO) are prepared by reactions of H2S with the solutions of Cu(OAc)2, CdCl2, Cdl2 Cd(OAc)2, Zn(OAc)2, HgCl2, and Ni(OAc)2 (OAc = OCOCH8), respectively. Organosols of mixed metal sulfides ZnxCd1-xS are obtained by reactions of H2S with DMF solutions of mixtures (of Cd(OAC)2 and Zn(OAc)2 in various ratios. Rayleigh scattering studies of these organosols using an Ar luer beam (lambda = 488 nm) show that the particle size of the colloidal metal sulfides and the stability of the organosols vary depending on the metal used on the conditions of the organosol preparation. The organosol of CuS in DMSO shows a particle size of 13-nm diameter which does not change at 25-degrees-C for 3 days. The organosol of CdS (0.1 M) in DMF has a particle size of 8-10-nm diameter, The particle size does not change for 2 weeks at -15-degrees-C under argon atmosphere. Ar laser irradiation at 17-degrees-C causes gradual increase in the particle size up to 30 nm n diameter and subsequent deposition of CdS. Addition of dodecanethiol or tetrabutylammonium bromide to the CdS organosol causes a blue-shift of the peak of the absorption spectrum. Organosols of ZnS, prepared by reaction of H2S with a DMF solution of Zn(OAc)2, are much less stable than those of CdS and begin to give a precipitate of Zns after 1 h at room temperature. The light-scattering study reveals that the average particle size of ZnS increases from 17 to 500 nm in diameter during 70 min at room temperature, Addition of acetone, Et2O, or methanol to these organosols causes precipitation of the corresponding metal sulfides, whose X-ray diffraction patterns agree with the authentic data. Black or orange organosols of HgS are obtained by reaction of H2S with a DMF or DMSO solution of HgCl2. Recovered solid from the orange organosol by addition of Et2O shown a diffraction pattern identical with that of a-HgS, while the black organosol shows diffraction pattern due to beta-HgS or those assignable to mixtures of alpha- and beta-HgS depending on the preparation conditions. Organosols of NiS, obtained by reaction of H2S with Ni(OAc)2, in DMSO, do not show observable light scattering due to the relatively small particle size (<4-nm diameter). Electrophoresis of these organosols indicates the presence of negative charge on the metal sulfide particle surface that is similar to the colloidal particles of the metal sulfides in water.