Talk:Triphenylphosphine selenide

Structure

The other compounds in this series (Triphenylphosphine oxide, Triphenylphosphine sulfide) are depicted as having R₃P=X bonding but here it's R₃P⁺-Se^-. Is that right and if so is this a selenium ylide?--Project Osprey (talk) 10:29, 19 December 2014 (UTC)

Good point. I'll follow consensus advice, I am no super expert. I was just following the trend that multiple bonds to heavy elements are rare, rarer still when both elements are heavy. --Smokefoot (talk) 14:01, 19 December 2014 (UTC)

I have no experience with selenium chemistry at all (fortunately!) so I don't know either. I have found a review (10.1021/ic00185a010) which would sort of imply a P=As bond, the length certainly seem about right. I'll let you make the final call though --Project Osprey (talk) 14:32, 19 December 2014 (UTC)

Oh the paper on As=P is a spin-off of a famous exception to rarity of multiple bonds between heavy mg elements. You'll notice huge substituents sterically prevent conversion RAs=PR to -(RAs-PR)- ring or polymer. To the right is the prototype invented by the Japanese organophosphorus chemist Masaaki Yoshifuji, taken from our article diphosphenes.

Yoshifuji's diphosphene. The phenyl rings are rotated out of the plane but are shown as coplanar for simplicity of presentation.

There is nothing really bad about the multiple bonds, but because the atoms are large, they just rather polymerize. See Ceiling temperature. Because of the rarity of multiple bonding between heavy main group elements, this theme once was a major target and there are now several examples, but alway w mega substituents. --Smokefoot (talk) 19:18, 19 December 2014 (UTC)