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

[(2,4,6-tBu3C6H2)InPSi(tBu)3]2 was synthesized and X-ray crystallographically characterized as the first dimeric phosphanylidene indane with three-coordinate indium and phosphorus atoms. The analogous reaction with the gallium derivative and the smaller triisopropylsilyl ligand leads to the formation of (2,4,6-tBu3C6H2)2GaP(H)SiiPr3 as a monomeric phosphanylgallane with a three-coordinate gallium atom.