Polyatomic Molecules Flashcards
Molecules with 2 electron pairs around central atom?
AX2 Linear 180 degrees
Molecules with 3 electron pairs around central atom?
AX3 Trigonal planar 120 degrees
Molecules with 4 electron pairs around central atom?
AX4 Tetrahedral 109.5 degrees
Molecules with 5 electron pairs around central atom?
AX5 Trigonal bipyramid 120 and 90 degrees
Molecules with 6 electron pairs around central atom?
AX6 Octahedral 90 degrees
Molecules with 7 electron pairs around central atom?
AX7 Pentagonal bipyramidal 72 and 90 degrees
Three bonding pairs one lone pair?
AX3E Trigonal pyramidal 107.8 degrees
Two bonding pairs one lone pair?
AX2E Bent 95 degrees
Four bonding pairs one lone pair?
AX4E See saw/sawhorse 103 degrees
Three bonding pairs two lone pairs?
AX3E2 T shaped 87 degrees
Five bonding pairs one lone pair?
AX5E Square based pyramid 85 degrees
Four bonding pairs two lone pairs?
AX4E2 Square planar less than 90 degrees
Two bonding pairs two lone pairs?
AX2E2 V shapes 104.5 degrees
One bonding pair three lone pairs?
AXE3 Linear
Hard acids?
If a molecules or ion has largely electrostatic, ionic interactions, small or highly charged centre, it will be classed as a hard acid or base, more electronegative an atom the harder it will be
Hard acids prefer to complex with hard bases H+ Mg2+ BF3 Ti4+ Mn+ Fe3+
Hard bases?
F-, OH2, NH3, O2-
Soft acids?
Largely covalent interactions soft acids or bases, soft-soft interactions are more orbital based and a soft acid would prefer to complex with soft bases
Cu+ Pd2+ Hd2+ Pt2+
Soft bases?
Br- PH3 BH3 I- CN-
Chelate effect?
A complex containing 5 or 6 membered rings is more stable than the one without the chelate ring, for example complexes with 3 chelate rings are approximately 2 times more stable than those with six mono dentate ligands, this is a combined kinetic and thermodynamic effect since it is tropically driven. the increase in disorder in the reaction involving the chelate lianas is positive and means this reaction is highly favoured
Kf?
If Kf is large the ligand binds more tightly to the metal centre than H2O
If Kf is small the ligands bind less tightly than H2O
Delta isomers?
Right hand screw
Lambda isomers?
Left hand screw
Ligand?
Group or atom that gives a metal centre a pair of electrons, normally through an available lone pair
Order of repulsion?
LP-LP > LP-DB > LP-SB > DB-DB > DB-SB > SB-SB
Ligands and charge?
en neutral pn neutral biped neutral phen neutral [acac]- 1 minus [ox]2- 2 minus dien neutral terry neutral [edta]4- 4 minus
Hard ligands?
Small electronegative donor atoms, hard metals carry a high charge or have high charge density, bonding between hard metals and hard ligands has a high degree of ionic character
Soft ligands?
Soft metals have a lower charge and tend to be larger and more polarisable, ligands that have larger more polarisable donor atoms, the bonding between soft metals and soft ligands has a high degree of covalent character
Examples of hard metals?
Ti4+ VO2+ Sc3+ Cr3+ Fe3+ Co3+ Cr2+ Mn2+
Examples of intermediate metals?
Fe2+, Co2+, Ni2+, Cu2+, Zn2+, Rh3+, Ir3+, Ru3+, Os3+
Examples of soft metals?
Cu+, Ag+, Au+, Pd2+, Cd2+, Pt2+, Hg2+
Examples of hard ligands?
F-, Cl-, OH-, O2-, NO3-, SO42-, CO32-, H2O, NH3
Examples of intermediate ligands?
Br-, N3-, NCS-, NO2-, SO32-
Examples of soft ligands?
H-, R-, CN-, I-, SCN-, CO, PR3, SR2
