1Chapter 24 Transition Metals & Coordination Compounds Properties of Transition MetalsReview Electron ConfigurationTrends in the Periodic TableCoordination CompoundsThe BasicsExample of NamingStructure and Isomerization
2Transition Metals contain e- in d Orbitals Breath – slow down!
424.2 Properties of Transition Metals Moderate to High DensitiesGood Electrical ConductivityHigh Melting PointsModerate to Extreme HardnessDue 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.
9Atomic SizeKeep it simple! breathException 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.
11Ionization 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.
13ElectronegativityAu: EN = 2.4Compared toP: EN = 2.1 !!Gold breath slow downException to the trend: There is an increase in electronegativity from the 3d (1st row transition metals) to the 4d (2nd row transition metals).
14Oxidation StatesScandiumIn general, stability is found in full or half-full shells, and in a configuration that looks like a noble gas.
1524.3 Coordination Compounds Complex 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 chargeThe combination of a complex ion and counter ions results in a coordination compound*Corrected 2:30 pm)David N. Blauch -
16A 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 NumberExample: [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 CoOther cobalt(III) coordination compounds[Co(NH3)6]Cl3[Co(NH3)5Cl]Cl2[Co(NH3)4Cl2]Cl
17Coordinate Covalent Bonds Lewis Acid-Base Adduct – the ligand donates it’s electrons to the empty metal orbitals to form a coordinate covalent bondL:MLewis AcidLewis BaseAdduct
19Chelating AgentsLigands can have one or more bonding pairs of electronsMonodentateBidentate or PolydentateComplex ions with bidentate or polydentate ligands are chelates, and the coordinating ligands are chelating agentsCoEDTA is hexadentate
20GeometriesAnne Marie Helmenstine, Ph.D., About.com Guide
21Naming 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 ionManganese(II)Anion 2ndSulfatePentaamminecarbonylmanganese(II) sulfate
2224.4 Structure & Isomerism Isomers Structural Isomers Stereoisomers Coordination IsomersLinkage IsomersStereoisomersGeometric Isomerscis-transfac-merOptical IsomersSame formula – different structuresSame connectivities –different spacial arrangementsDifferent connectivitiesLigands & counter ions trade placesLigands coordinate in different waysDifferent spacial arrangementsMirror images
23Structural Isomers Coordination Isomers pentaamminesulfatochromium(III) bromidepentaamminebromochromium(III) sulfateDavid N. Blauch -
24Structural Isomers Linkage Isomers pentaamminenitrocobalt(III) ionpentaamminenitritocobalt(III) ionDavid N. Blauch -
25Stereoisomers Geometric Isomers: cis-trans cis-diamminedichloroplatinum(II)trans-diamminedichloroplatinum(II)David N. Blauch -
26Stereoisomers Geometric Isomers: fac-mer fac-triamminetrichlorocobalt(III)mer-triamminetrichlorocobalt(III)David N. Blauch -
27Stereoisomers Optical Isomers Mirror ImagesNon-superimposableEnantimomersChiral: optically active (rotates polarized light)
28Chirality Determining Optical Activity facmerDavid N. Blauch -