Talk:Ligand cone angle

Solid or planar?

It is stated that the ligand cone angle is a solid angle but then all values are given as planar angles! 150.227.15.253 (talk) 09:00, 2 August 2010 (UTC)[reply]

It's just a angle, at least as it was originally defined. One of the references (which I haven't read), from 2009, has the title "The Extension of the Solid-Angle Concept to Bidentate Ligands". Maybe they do mean solid angles. But again, the good-old-fashioned Tolman angle is just a regular angle. --Itub (talk) 13:44, 7 August 2010 (UTC)[reply]

Algebra

Adding up the half angles and multiplying by two is that same as multiplying by one, no? "In such asymmetric cases, the substituent angles' half angles, θi/2, are averaged and then doubled to find the total cone angle, θ." Same goes for the equation below that... Pelirojopajaro (talk) 13:13, 27 October 2018 (UTC)[reply]

It seems like it is easier to measure the half-angle because the three R groups on the central atom are arranged in 3D space. For a symmetric case (PR₃), to measure the full angle, you need to envision rotating a trigonal pyramid about its altitude-axis to find the circle that encloses the base. To measure the half-angle, you simply need the altidude and the distance from it to one of the base vertices. To determine the circle, you likewise need that vertex. So why bother with the "find the circle" step? For a non-symmetric case, you need to somehow average the enclosing circles—and the base might not even be perpendicular to the M–P axis, which is the reference for the angle—vs just averaging the three separately measured half-angles based on their separate points. DMacks (talk) 17:02, 27 October 2018 (UTC)[reply]