Transition Metals. Flashcards
What are the four standard properties of transition metals.
Form Complexes.
Formation of coloured ions.
Variable oxidation states.
Catalytic activity.
Define a transition metal.
One which formes at least one stable ion with a partially full d-sub shell of electrons.
Define a ligand.
An atom ion or molecule that forms a dative covalent bond by donating a lone electron pair to a central transition metal ion.
Define a Complex.
A central metal ion surrounded by ligands.
State why Zn is not a transition metal.
Zn only has the ability to form Zn2+ and so has a complete d orbital of electrons , hence does not meet the definition of having a partially complete d sub shell.
Define the term Co-ordination number.
The number of coordinate bonds formed to a central metal ion in a complex.
Define the term monodentate ligand.
Form one coordinate bond per ligand
Define the term bidentate ligand.
Can form two coordinate bonds per ligand.
Define the term multidentate ligand.
general term: ligand that have more than one Atom with a lone pair capable of coordinate bonding to a central metal ion.
Give some examples of monodentate ligand.
H20, NH3 and Cl -
What needs to be remembered about how ligands form bonds.
If an atom on the ligand has been used for forming a bond with lone pairs , it can’t donate another lone pair from the same atom , another atoms lone pairs would need to be used if it was multidentate. Sometimes even if there are more possible atoms available the ligand can be limited by being bidentate.
Give some examples of bidentante ligands.
Ethan-1,2-diamine , ethandioate- oxoate ion- which does have 4 oxygens but only uses 2 , and benzene-1,2-diol are all bidentate.
Give an example of a hexadentate ligand. State where the Lone pairs come from.
EDTA is the main hexadentate ligand. The lone pairs come from 2 nitrogen atoms and 4 oxygen atoms.
What shapes do complexes with small ligands typically form , For example [Ni(NH3)6]2+ or [Cu(H20)6]2+. NH3 and H20 are small ligands.
Small ligands often form octahedral shaped complexes.
Draw both [Ni(NH3)6]2+ , [Cu(H20)6]2+
Both octehedral.
What types of ligands will generally form tetrahedral shaped complexes and give an example of a ligand that does this.
Larger ligands like Cl- form tetrahedral complexes.
Draw out a [CuCl4]2-
should be tetrahedral.
What two shapes can complexes with coordination number 4 form.
tetrahedral or square planar.
generally tetrahedral but can be square planar for cis plantin which is platinum with stuff or nickel stuff is ocasinly square planar. Chloride ions are generally tetrahedral.
As a rule platinum will be square planar.
what shape is [Ni(NH32)Cl2] and [Ni(Cn)4]2-
square planar
Give an example of a linear complex and state a use for this complex.
Tollens reagent is a linear complex [Ag(NH3)2]+
What is the requirement for a complex to exhibit geometric E/Z isomerism.
Must be octahedral or square planar in shape.
Draw and name both the isomers of [Ni(NH3)2Cl2]
Square planar so will have a cis and trans form , e and z.
Draw and name both isomers of [Cr(H20)4Cl2]+
This is ocehedral so will have a e and z form , depending if the cl atom is diagonaly apart or not.
Give the condition needed for optical isomerism in a complex and state how this differs from organic.
complexes with 2 or more bidentate ligands will form two optical isomers. No need to think in terms of specific chiral carbon case as with organic the 4 different groups doesn’t mater here as they are still non superimposable.
Using en as an abbreviation for Ethan-1,2-diamine state the type of and draw out the isomerism shown in [Cr(en)3]2+ and also [CrCl2(en)2] and {Cr(C2O4)3 } 3-.
Ethan-1,2-diamine is a bidentate ligand and so there will be optical isomerism as shape is not important. See page 23 in the text book and also page 4 on the sheet for examples.
Note these types of complexes with coordination number six are still octahedral with the biodentate ligands, and so can be drawn as such with the wedges and dotted lines 90 degrees bond angle.
