Abstract: There is provided a polygermane compound forming a film having a high refractive index and thermal stability, and containing a sulfur atom-containing organic group as a group bonded to a germanium atom. A polygermane compound comprising a sulfur atom-containing organic group as a group bonded to a germanium atom, in which the sulfur atom-containing organic group is a group of Formula [1]: -L-Z??[1] where L is a single bond, a C1-6 alkylene group, or a C4-20 arylene group optionally substituted with a C1-6 alkyl group; and Z is a C1-20 sulfide group, a C1-14 cyclic sulfide group optionally substituted with a C1-6 alkyl group, a C2-20 alkyl group containing a sulfide bond, or a C5-20 aralkyl group containing a sulfide bond, with a proviso that when L is a single bond, Z is not a C1-20 sulfide group.

Abstract: There is provided a polygermane compound forming a film having a high refractive index and thermal stability, and containing a sulfur atom-containing organic group as a group bonded to a germanium atom. A polygermane compound comprising a sulfur atom-containing organic group as a group bonded to a germanium atom, in which the sulfur atom-containing organic group is a group of Formula [1]: -L-Z ??[1] where L is a single bond, a C1-6 alkylene group, or a C4-20 arylene group optionally substituted with a C1-6 alkyl group; and Z is a C1-20 sulfide group, a C1-14 cyclic sulfide group optionally substituted with a C1-6 alkyl group, a C2-20 alkyl group containing a sulfide bond, or a C5-20 aralkyl group containing a sulfide bond, with a proviso that when L is a single bond, Z is not a C1-20 sulfide group.

Abstract: There is provided a high refractive-index coating film and a production method of the high refractive-index coating film. The production method comprises producing a coating film containing a germanium compound containing a Ge—Ge bond as a backbone thereof, and baking the coating film under vacuum or in an inert gas atmosphere. The high refractive-index coating film produced by the method is soluble in a solvent and has a high moldability and film-formation property, and has a high refractive index of 1.8 or more and further 2.3 or more, and is chemically stable.