Transition Metals & Coordination Compounds

Chapter 24Transition Metals &Coordination Compounds24.2 Properties of Transition MetalsReview Electron ConfigurationTrends in the Periodic Table24.3 Coordination Compounds The BasicsExample of Naming24.4 Structure and Isomerization

Transition Metals contain e- in d Orbitals

http://www.can-do.com/uci/lessons98/Periodic.htmlhttp://www.can-do.com/uci/lessons98/Periodic.htmlBreath slow down!2Why Are Transition Metals & Coordination Compounds Important?Therapeutic drugsChemical SensorsColoring agents PaintsCosmeticsBiological MoleculesHemeglobinChlorophyllGems (Jewelry & Technological Applications)Rubies, Emeralds, Garnets, etc.Lasers

24.2 Properties of Transition MetalsModerate to High DensitiesGood Electrical ConductivityHigh Melting PointsModerate to Extreme Hardness

http://www.tutorvista.com/chemistry/shapes-of-d-orbitalsDue to the delocalization of d electrons in metallic bondingExceptions: Elements with filled d orbitals, which prevents d-d bonding. Hg has a low melting point and is liquid at room temperature.

Electron Configuration

Increasing Energy(n-1)d(n-2)fElectron Configuration

[noble gas] ns2 (n-1)dx

[noble gas] ns2 (n-2)f14 (n-1)dx Slow down - Breath6Electron Configuration

[Kr]5s24d2http://malaxoschemistry.wikispaces.com/Periodic+TableAtomic Size

Decreasing SizeIncreasIng

S izehttp://malaxoschemistry.wikispaces.com/Periodic+TableAtomic Size

Exception to the trend: Electrons in the f-orbitals are not effective at shielding outer shell electrons from nuclear charge. So, the outer electrons are held in close this is known as lanthanide contraction.Keep it simple! breath9Ionization Energy

IncreasesDecreaseshttp://malaxoschemistry.wikispaces.com/Periodic+Table

Ionization EnergyException to the trend: Note that 5d elements have a greater ionization energy. This is again due to outer shell electron being held closer to the nucleus, so it take more energy to pull them away. Electronegativity

http://malaxoschemistry.wikispaces.com/Periodic+TableIncreasesDecreases

ElectronegativityException to the trend: There is an increase in electronegativity from the 3d (1st row transition metals) to the 4d (2nd row transition metals). Au: EN = 2.4Compared to P: EN = 2.1 !!Gold breath slow down13Oxidation States

In general, stability is found in full or half-full shells, and in a configuration that looks like a noble gas.Scandium1424.3 Coordination CompoundsComplex Ion - Central Metal bound to one or more ligandsLigands are Lewis Base* (electron donors) and can be either neutral or negatively chargedThe charge on the complex ion is balance by counter ions of opposite charge

The combination of a complex ion and counter ions results in a coordination compoundDavid N. Blauch - http://www.chm.davidson.edu/vce/index.htm

*Corrected 4/15/11 @ 2:30 pm)A Little BackgroundIn 1893, Swiss chemist Alfred Werner came up with the idea that a central metal could have 2 types of interactionsPrimary Valence Oxidation State of the central metalSecondary Valence Number of molecules or ions directly attached to the central metal or Coordination Number

Example: [Co(NH3)6]Cl3The Primary Valence or Oxidation State of Co is +3The Secondary Valence or Coordination Number is 6 (6 ammonia ligands are directly attached to Co

Other cobalt(III) coordination compounds[Co(NH3)6]Cl3[Co(NH3)5Cl]Cl2[Co(NH3)4Cl2]ClCoordinate Covalent BondsLewis Acid-Base Adduct the ligand donates its electrons to the empty metal orbitals to form a coordinate covalent bond

Lewis AcidLewis BaseML:AdductSome Common Ligands

Chelating AgentsLigands can have one or more bonding pairs of electronsMonodentateBidentate or Polydentate

Complex ions with bidentate or polydentate ligands are chelates, and the coordinating ligands are chelating agents

EDTA is hexadentatehttp://library.kiwix.org:4201/A/Inorganic_chemistry.htm

CoGeometries

Anne Marie Helmenstine, Ph.D., About.com Guide

Naming Coordination Compounds[Mn(CO)(NH3)5]SO4 (neutral ligands are written before charged ligands in the formula)Cation 1stName the ligands in alphabetical orderamminecarbonylAdd a prefix to indicate the number of ligandspentaammineName the metal ion Manganese(II)Anion 2ndSulfatePentaamminecarbonylmanganese(II) sulfate24.4 Structure & IsomerismSame formula different structuresDifferent connectivitiesSame connectivities different spacial arrangementsLigands & counter ions trade placesLigands coordinate in different waysDifferent spacial arrangementsMirror imagesStructural IsomersCoordination Isomers

David N. Blauch - http://www.chm.davidson.edu/vce/index.htmpentaamminesulfatochromium(III) bromidepentaamminebromochromium(III) sulfateStructural IsomersLinkage Isomers

David N. Blauch - http://www.chm.davidson.edu/vce/index.htmpentaamminenitrocobalt(III) ionpentaamminenitritocobalt(III) ionStereoisomersGeometric Isomers: cis-trans

cistransDavid N. Blauch - http://www.chm.davidson.edu/vce/index.htmcis-diamminedichloroplatinum(II)trans-diamminedichloroplatinum(II)StereoisomersGeometric Isomers: fac-merfacmer

David N. Blauch - http://www.chm.davidson.edu/vce/index.htmfac-triamminetrichlorocobalt(III)mer-triamminetrichlorocobalt(III)StereoisomersOptical IsomersMirror ImagesNon-superimposableEnantimomersChiral: optically active (rotates polarized light)

http://www.wikidoc.org/index.php/Chirality_%28chemistry%29

http://en.wikipedia.org/wiki/Chirality_%28electromagnetism%29ChiralityDetermining Optical Activity

facmerDavid N. Blauch - http://www.chm.davidson.edu/vce/index.htmChiralityDetermining Optical Activity

Superimposable - No optical activity