A bis(silaselenone) with two donor-stabilized Si=Se bonds from an unexpected stereoconvergent hydrolysis of a diselenadisiletane.

SiSe matters: Diselenadisiletane 2, formed from direct reaction of a racemic silylene 1 with elemental selenium, gives the first bis(silaselenone) upon hydrolysis with water (3; see picture, C gray, H white, N blue, O red, Se purple, Si green; d(Si=Se) = 215 pm). The reaction is stereoconvergent: only racemic forms of 3 are obtained from a mixture of racemic and meso forms of 2.