Synthesis and characterization of 1,3-bis[2,4,6-tri(tert-butyl)phenyl]-2,4-bis[tri(tert-butyl)silyl]-1,3-diinda-2,4-diphosphetane, a dimeric phosphanylidene indane with three-coordinate indium and phosphorus atoms

The metathesis reaction of potassium tri(tert-butyl)silylphosphanide with bis[2,4,6-tri(tert-butyl)phenyl]indium bromide gives (2,4,6-tBu3C6H2)2In–P(H)SitBu3 (1a), the subsequent elimination of tri(tert-butyl)benzene yields [(2,4,6-tBu3C6H2)In–PSitBu3]2 (2a) which can be regarded as a dimeric phosphanylidene indane. The X-ray structure confirms the dimeric nature of this 1,3-diinda-2,4-diphosphetane with three-coordinate indium and phosphorus atoms and short In–P bond lengths of 250 pm. The analogous reaction with the gallium derivative and the smaller potassium triisopropylsilylphosphanide leads to the formation of monomeric (2,4,6-tBu3C6H2)2Ga–P(H)SiiPr3 (1b) with three-coordinate gallium and phosphorus atoms.