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- Complex ion
- or Coordination compound
- or Coordination complexes
- Cu = Metal, acceptor atom, Lewis Acid
- NH3 = ligand, donor atom, Lewis Base
Whats it called when 1, 2, or more bonds are made with a ligand?
- Monodentate = 1
- bidentate = 2
- polydentate = 2 or more
A complex ion containing rings formed by polydentate ligands.
- The extra stability found in complexes that contain chelate rings.
- Ni2+(aq) + 6NH3(aq) <--> [Ni(NH3)6]2+(aq)
- Kform = 2.0 x 108
- Ni2+(aq) + 3en(aq) <--> [Ni(en)3]2+(aq)
- Kform = 4.1 x 1017
- Seeing as 4.1 x 1017 >> 2.0 x 108 tells us that [Ni(en)3]2+ is much more stable.
Rules for writing formulas for complexes
- 1. The symbol for the metal ion is always given first, followed by the ligands.
- 2. When more than one kind of ligand is present, anionic ligands are written first (in alphabetical order), followed by neutral ligands (also in alphabetical order).
- 3. The charge on the complex is the algerbraic sum of the charge on the metal ion and the charges on the ligands.
- 4. The formula is placed inside of square brackets with the charge of the complex as a superscript outside the brackets, if it is not zero.
Rule #1 of nomenclature for coordination complexes
1. Cationic species are named before anionic species.
Rule #2 of nomenclature for coordination complexes
- 2. Names of anionic ligands always end in suffix -O.
- Anion Ligand
- chloride Cl- chloro-
- bromide Br- bromo-
- cyanide CN- cyano-
- oxide O2- oxo-
- cabonate CO32- carbonato-
- thiosulfate S2O32- thiosulfato-
- thiocyanate SCN- thiocyanato- (bonded to S)
- isothiocyanato- (bonded to N)
- oxalate C2O42- oxalato-
- nitrite NO2- nitroto (bonded to O; written ONO in the formula for the complex)
Rule #3 of nomenclature for coordination complexes
3. A neutral ligand is given the same name as the neutral molecule.
Rule #4 of nomenclature for coordination complexes
4. When there is more than one of a particular ligand, their number is specified by the prefixes di-=2, tri-=3, tetra-=4, penta-=5, hexa-=6, and so forth. When confusion might result by using these prefixes, the following are used instead: bis-=2, tris-=3, tetrakis-=4.
Rule #5 of nomenclature for coordination complexes
5. In the formula of a complex, the symbol for the metal is written first, followed by those of the ligands. Among the ligands, anionic ligands written first (in alphabetical order), followed by neutral ligands (also in alphabetical order). In the name of the complex, the ligands are named first, in alphabetical order without regard to charge, followed by the name of the metal.
Rule #6 of nomenclature for coordination complexes
- Negative (anionic) complex ions always end in the suffix -ate.
- Metal Metal as named in an anionic complex
- aluminum aluminate
- chromium chromate
- manganese manganate
- nickel nickelate
- cobalt cobalate
- zinc zincate
- platinum platinate
- vanadium vanadate
- Metals in their latin names
- Metal Stem Metal in an anionic complex
- iron ferr- ferrate
- copper cupr- cuprate
- lead plumb- plumbate
- silver argent- argentate
- gold aur- aurate
- tin stann- stannate
Rule #7 of nomenclature for coordination complexes
- 7. The oxidation state of the metal in the complex is written in Roman numerals within parentheses following the name of the metal.
- [Ni(CN)4]2- tetracyanonickelate(II) ion
- K3[CoCl6] potassium hexachlorocobaltate(III)
- [CoCl2(NH3)4]+ tetraamminedichlorocobalt(III) ion
- Na3[Co(NO2)6] sodium hexanitrocobaltate(III)
- [Ag(NH3)2]+ diamminesilver(I) ion
- [Mn(en)3]Cl2 tris(ethylenediamine)manganese(II) chloride
- [PtCl2(NH3)2] diamminedichloroplatinum(II)
Write the formula for the complex ion formed by the ion Cr3+ and six NO2- ions as ligands. Decide wheather the complex could be isolated as a chloride salt or a potassium salt, and write the formula for the appropriate salt.
- Six NO2- ions contribute a total charge of 6-; the metal contributes a charge of 3+. The algerbraic sum is (6-) + (3+) = 3-. The formula of the complex ion is therefore [Cr(NO2)6]3-.
- Because the complex is an anion, it requires a cation to form a neutralsalt, therefore potassium must be the salt giving us K3[Cr(NO2)6].
Chelate Effect with small values
- ie: [Ni(NH3)6]2+(aq) <-->Ni2+(aq) + 6NH3(aq)
- kform = 5.0 x 10-9
- [Ni(en)3]2+(aq) <--> Ni2+(aq) + 3en(aq)
- kform = 2.4 x 10-18
- This tells us that is the more stable compound and therefore tells us that the ∆G is greater(?????)
- The number of donor atoms attached to the metal ion.
- [Ni(CN)4]2- = 4
- [Cr(H2O)2(en)2]3+ & [Cr(en)3]3+ = 6 (en) = 2 each
- [Ag(NH3)2]+ = 2
Coordination number and geometry
- #2 = linear (possably bent(??))
- #4 = tetrahedral or square planner
- #6 = octahedral,
Metal ion and Coordination number
- Al3+ = 4,6
- Sc3+ = 6
- Ti4+ = 6
- V3+ = 6
- Cr3+ = 6
- Mn2+ = 6
- Fe2+ = 6
- Fe3+ = 6
- Co2+ = 4,6
- Co3+ = 6
- Ni2+ = 4,6
- Cu+ = 2,4
- Cu2+ = 4,6
- Zn2+ = 4
- Pd2+ = 4
- Ag+ = 2
- Pt2+ = 4
- Pt4+ = 6
- Au+ = 2,4
- Au3+ = 4
The existance of isomers whose structures differ only in spatial orientations (e.g. geometric isomers and optical isomers).
One of a set of isomers that differ only in geomitry.
The existance of isomers whose molecules have identicle atomic organizations but diferent geometries; cis-trans isomers.
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