Long chain diphosphines

Figure 11.30 An insulated molecular wire based on a platinum(II) polyalkyne surrounded by two long-chain diphosphines. The polyalkyne wire (shown dark in the middle of the structure) is barely visible within the insulation.45...

Diphosphines with long chains between the P atoms, for example, Bu2P(CH2)5 gPBu2, can span trans positions in square complexes or give large ring systems, (10-LXXI) and (10-LXXII), respectively. A similar situation has also been found in an octahedral complex,86 where the trans isomer has been shown to be more stable than the cis. 

Dinuclear complexes with a bridging polyynediyl ligand and diphosphine ligands with long methylene chains between the two P atoms show a structure in which the alkylene chains are double-helixed around the polyyne ligand... 

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