> For molecular systems, there are three types of mirrorplanes: If the plane is perpendicular to the vertical principalaxis, it is labeled r.(h-horizontal) If the plane contains the principal axis, it is labeled(v-vertical)a If a o, plane contains the principal axis and morespecifically bisects the angle between two adjacent 2-fold axes, it is labeled a.(d-diagonal)
For molecular systems, there are three types of mirror planes: If the plane is perpendicular to the vertical principal axis, it is labeled sh . (h-horizontal) If the plane contains the principal axis, it is labeled sv . (v-vertical) If a sv plane contains the principal axis and more specifically bisects the angle between two adjacent 2- fold axes, it is labeled sd . (d-diagonal)
Does BF, have On , O, and/or oa planes ?C The BF3 plane is a , planeEach plane that contains a B-F bond and the C axis is a o,and, meanwhile, a a plane
Does BF3 have sh , sv and/or sd planes ? • The BF3 plane is a sh plane. • Each plane that contains a B-F bond and the C3 axis is a sv and, meanwhile, a sd plane
If the plane contains the principal axis then it is labeled o,Example: H,O- Has a C, principal axis- Has two planes that contain the principal axis, o, and
If the plane contains the principal axis then it is labeled sv . • Example: H2O – Has a C2 principal axis. – Has two planes that contain the principal axis, sv and sv ’. H O H sv sv
If a o, plane contains the principal axis and bisects the anglebetween two adjacent 2-fold axes, then it is a , (DihedralmirrorplanesExample: H,C=C=CH,CHEach HCH plane is a o,/oa plane!
Example: H2C=C=CH2 C2 C2 sd sd If a sv plane contains the principal axis and bisects the angle between two adjacent 2-fold axes, then it is a sd .(Dihedral mirror planes ) • Each HCH plane is a sv /sd plane!
5)Theimproperrotationaxisa. n-fold rotation-reflection axis of symmetry,or rotary-reflection axis (S,)A body has an S, axis if rotation by 360%n about the axis,followed by reflection in a plane perpendicular to the axisproduces a configuration indistinguishable from the original oneAxisbisectstheH-C-HbondSI = o,C!Reflectanglethroughaplanethat isperpendicularRotateto the originalthroughrotationaxis90C1Indistinguishable!Distinguishable!S4=ES SI = 0nC4!S3 = S41. S41. S41 = 0, C43S2 = S41. S41 =(0,C4) (g, C4) = (g,)2C? =C,I
A body has an Sn axis if rotation by 360/n about the axis, followed by reflection in a plane perpendicular to the axis, produces a configuration indistinguishable from the original one. a. n-fold rotation-reflection axis of symmetry, or rotary-reflection axis (Sn ) 5) The improper rotation axis S4 C4 1 sh S4 1 = sh C4 1 S4 2 = S4 1 S4 1 S4 3 = S4 1 S4 1 S4 1 = sh C4 3 S4 4 = E S4 1 = sh C4 1 = (sh C4 1 )(sh C4 1 ) = (sh ) 2C4 2 =C2 1 Distinguishable! Indistinguishable!