Herein we report the first synthesis of a 1-magnesium-2,3-disilacyclopropene and a related bis(disilenide). Reduction of (boryl)tribromosilane (1, boryl = (HCArN)(2)B, Ar = 2,6-iPr(2)C(6)H(3)) with magnesium in THF afforded boryl-substituted magnesium complex [(boryl)Si](2)Mg(THF)(3) (2) in good yield, whereas reduction of (boryl)trichlorosilane (3) with KC, in THF led to the isolation of bridged alkoxy alkyl bis(disilenide) (THF)K(boryl)Si=Si(boryl)O(CH2)(4)(boryl)Si=Si(boryl)K(THF) (4) via ring opening of a THF molecule. X-ray diffraction analysis of 2 confirmed the presence of the novel Si2Mg three-membered ring as well as the Si=Si double bond, which existed in a noticeably twisted B-Si-Si-B array. Complex 2 also represents the first reported example of a stable disilyne dianion.