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Key Concepts PowerPoint

Chapter 20
Transition Elements and Coordination Chemistry

  
20-01
Title
 The transition elements
Caption
 Figure 20.1 The transition elements (d-block elements, shown in yellow) are located in the central region of the periodic table between the s-block and p-block main-group elements. The two series of inner transition elements (f-block elements, shown in green) follow lanthanum and actinium.
Notes
 Transition elements located in the central region of the periodic table
Keywords
 transition elements, d-block elements
20-01-01UN
Title
 Electron configurations of Cr and Cu
Caption
 Anomalous electron configurations frequently occur if the atom can attain half-filled or completely filled subshells.
Notes
 The electron configurations of chromium and copper deviate from the expected filling pattern for the subshells.
Keywords
 chromium, copper, electron configuration
20-01-03UN
Title
 Key Concept Problem 20.2
Caption
 On the periodic table below, locate the transition metal atom or ion with the following electron configurations. Identify each atom or ion.
Notes
 Key Concept Problem 20.2
Keywords
 electron configurations
20-02
Title
 Properties of transition elements
Caption
 Figure 20.2 Relative melting points of the transition elements. Melting points reach a maximum value in the middle of each series.
Notes
 Within any transition series, the melting points increase for the first three or four elements, then show a general decrease.
Keywords
 melting points
20-03
Title
 Atomic radii
Caption
 Figure 20.3 Atomic radii (in pm) of the transition elements. The radii decrease with increasing atomic number and then increase again toward the end of each transition series. Note that the second-and third-series transition elements have nearly identical radii.
Notes
 Due to the lanthanide contraction, second-and third-series transition elements have similar atomic radii, so the heavier third-series elements are much denser than the lighter second-series elements.
Keywords
 atomic radii, lanthanide contraction, density
20-04
Title
 Lanthanide atomic radii
Caption
 Figure 20.4 Atomic radii (in pm) of the lanthanide elements. The radii generally decrease with increasing atomic number.
Notes
 Atomic radii of the lanthanide elements.
Keywords
 lanthanides, atomic radii
20-05
Title
 Transition metal densities
Caption
 Figure 20.5 Relative densities of the transition metals. Density initially increases across each series and then decreases.
Notes
 Relative densities of the transition metals. The densities of the transition metals are inversely related to their atomic radii.
Keywords
 density, atomic radii
20-06
Title
 Oxidation states
Caption
 Figure 20.6 Common oxidation states for first-series transition elements. The states encountered most frequently are shown in red. The highest oxidation state for the group 3B-7B metals is their periodic group number, but the group 8B transition metals have a maximum oxidation state less than their group number. Most transition elements have more than one common oxidation state.
Notes
 Common oxidation states for first-series transition elements. All first-series transition metals except scandium form +2 ions.
Keywords
 oxidation state, first-series
20-08-01UN
Title
 Acid strength of chromium hydroxides
Caption
 Chromium(III) hydroxide is amphoteric; however, chromium(II) hydroxide is a typical basic hydroxide which dissolves in acid solution but not in excess base. Chromium(VI) hydroxide (chromic acid) is a strong acid.
Notes
 The higher the oxidation state of the central atom, the more acidic the hydroxo species.
Keywords
 metal hydroxide, acidity, oxidation state
20-09-01UN
Title
 Chromate and dichromate ions
Caption
 Ball-and-stick models of the chromate ion, CrO42-, and dichromate ion, Cr2O72-.
Notes
 Structures of the chromate ion, CrO42-, and dichromate ion, Cr2O72-
Keywords
 chromate, dichromate
20-11
Title
 Complexes of copper
Caption
 Figure 20.11 When an aqueous solution of CuSO4 (left) is treated with aqueous ammonia, a blue precipitate of Cu(OH)2 forms (center). On the addition of excess ammonia, the precipitate dissolves, yielding the deep blue Cu(NH3)42+ion (right).
Notes
 Three test tubes showing the different copper(II) complexes
Keywords
 copper
20-12
Title
 Coordination geometries of metal complexes
Caption
 Figure 20.12 The arrangement of ligand donor atoms (L) in MLn complexes with coordination numbers 2, 4, and 6. In the octahedral arrangement, four ligands are at the corners of a square, with one more above and one below the plane of the square.
Notes
 Coordination geometries of metal complexes, showing linear, tetrahedral, square planar, and octahedral geometries
Keywords
 coordination geometry
20-12-01UN
Title
 Structure of the [Pt(NH3)Cl5]-ion
Caption
 Ball-and-stick model of the [Pt(NH3)Cl5]-ion.
Notes
 Structure of the [Pt(NH3)Cl5]-ion, for Worked Example 20.3
Keywords
 platinum, coordination compound
20-13
Title
 Common ligands
Caption
 Figure 20.13 Structures of some common ligands. Ligand donor atoms are in color. The thiocyanate ion can bond to a metal through either the S atom or the N atom.
Notes
 Structures and coordinating abilities of some common ligands
Keywords
 ligand, coordination compound
20-14
Title
 Chelating ligands of cobalt(III) complexes
Caption
 Figure 20.14 (a) Molecular model and (b) shorthand representation of the [Co(en)3]3+ion. The complex contains three cobalt-ethylenediamine chelate rings. In (b), the symbol N-N represents a bidentate NH2CH2CH2NH2 ligand, which spans adjacent corners of the octahedron. (c) Molecular model and (d) shorthand representation of the [Co(EDTA)]-ion. The hexadentate EDTA4-ligand uses its two N atoms and four O atoms to bond to the metal, thus forming five chelate rings.
Notes
 Ethylenediamine and EDTA as chelating ligands on cobalt(III)
Keywords
 chelate, ethylenediamine, EDTA
20-15
Title
 The porphine molecule
Caption
 Figure 20.15 (a) The structure of the porphine molecule. Loss of the two NH protons gives a planar, tetradentate 2-ligand that can bond to a metal cation. The porphyrins are derivatives of porphine in which the peripheral H atoms are replaced by various substituent groups. (b) Schematic of the planar heme group, the attached protein chain, and the bound O2 molecule in oxyhemoglobin and oxymyoglobin. The Fe(II) ion has a six-coordinate, octahedral environment, and the O2 acts as a monodentate ligand.
Notes
 Structural similarity between the porphine molecule and the porphyrin heme
Keywords
 porphine, porphyrin, heme
20-15-01UN
Title
 Naming coordination compounds
Caption
 Three examples illustrating the trend in the nomenclature of coordination compounds.
Notes
 Older literature named the ligand water aquo instead of aqua. However, the ending -o implies an anionic ligand. Ammonia as a ligand has the name ammine, with two m's. If one or more of the hydrogen atoms are replaced by groups of atoms bonded through carbon, the resulting ligand is an organic amine, with one m.
Keywords
 coordination compounds, nomenclature
20-16
Title
 Isomerism of coordination compounds
Caption
 Figure 20.16 Classification scheme for the kinds of isomers in coordination chemistry. See the text for examples.
Notes
 Isomers have the same chemical formula but different physical and chemical properties
Keywords
 isomers
20-17
Title
 Linkage isomers
Caption
 Figure 20.17 Samples and structures of (a) the nitro complex [Co(NH3)5(NO2)]2+, which contains an N-bonded NO2-ligand, and (b) the nitrito complex [Co(NH3)5(ONO)]2+, which contains an O-bonded NO2-ligand.
Notes
 Linkage isomers arise when a ligand can bond to a metal through either of two different donor atoms
Keywords
 isomers
20-18
Title
 Diastereomers of cisplatin
Caption
 Figure 20.18 Diastereoisomers of the square planar complex Pt(NH3)2Cl2. The two compounds have the same connections among atoms but different arrangements of the atoms in space.
Notes
 Cis and trans isomers of cisplatin
Keywords
 diastereomers, cisplatin
20-19
Title
 Diastereomers of [Co(NH3)4Cl2]+
Caption
 Figure 20.19 Diastereoisomers of the Co(NH3)4Cl2]+ion. Although they may appear different, cis isomers (a) and (b) are identical, as can be seen by rotating the entire complex by 90° about a Cl-Co-NH3 axis. Similarly, trans isomers (c) and (d) are identical.
Notes
 When counting diastereomers, students frequently arrive at too many because they draw the same isomer in different orientations.
Keywords
 diastereomers
20-19-01
Title
 Structure of [Pt(NH3)3Cl]+
Caption
 Formula and ball-and-stick model of [Pt(NH3)3Cl]+.
Notes
 Structure of [Pt(NH3)3Cl]+ for Worked Example 20.6
Keywords
 isomers
20-19-03
Title
 Cis and trans isomers
Caption
 Ball-and-stick models of the cis/trans isomers of Pt(NH3)2Cl(NO2).
Notes
 Structures of the cis and trans isomers of Pt(NH3)2Cl(NO2) for Worked Example 20.6
Keywords
 isomers
20-19-04
Title
 Cis and trans isomers
Caption
 Formulas and ball-and-stick models of [Pt(NH3)4ClBr]2+.
Notes
 Structures of the cis/trans isomers of [Pt(NH3)4ClBr]2+for Worked Example 20.6
Keywords
 isomers
20-19-05
Title
 Diastereomers of Co(NH3)3Cl3
Caption
 Ball-and-stick models of the diastereomers of Co(NH3)3Cl3.
Notes
 Structures of the diastereomers of Co(NH3)3Cl3 for Worked Example 20.7
Keywords
 diastereomers
20-19-07UN
Title
 Key Concept Example 20.8
Caption
 Consider the following isomers of the [Co(NH3)4(H2O)Cl]2+ion:
Notes
 Key Concept Example 20.8
Keywords
 isomers
20-19-08UN
Title
 Solution to Example 20.8
Caption
 Isomers 1 and 4 are identical, as can be seen by rotating 1 counterclockwise by 90 degrees about the vertical axis.
Notes
 Solution to Key Concept Example 20.8
Keywords
 isomers
20-19-09UN
Title
 Solution to Example 20.8
Caption
 Isomers 2 and 3 differ from 1 and 4 and are identical, as can be seen by rotating 2 clockwise by 90 degrees about the x axis and then counterclockwise by 90 degrees about the y axis.
Notes
 Solution to Key Concept Example 20.8
Keywords
 isomers
20-19-10UN
Title
 Key Concept Problem 20.9
Caption
 Which of the following isomers of [Co(en)(NH3)3Cl]2+are identical, and which are different?
Notes
 Key Concept Problem 20.9
Keywords
 isomers
20-20
Title
 Chirality
Caption
 Figure 20.20 The meaning of a symmetry plane: An achiral object like the coffee mug has a symmetry plane passing through it, making the two halves mirror images. A chiral object like the hand has no symmetry plane because the two “halves” of the hand are not mirror images.
Notes
 Chirality, or handedness, requires the lack of a plane of symmetry
Keywords
 chirality
20-21
Title
 Chiral and achiral cobalt complexes
Caption
 Figure 20.21 The structures of the [Co(en)3]3+enantiomers and the achiral [Co(NH3)6]3+ion. [Co(en)3]3+has a helical structure in which the three en ligands lie along the threads of a screw. As the red arrows show, one enantiomer is “right-handed” in the sense that the screw would advance into the page as you rotated it to the right. The other enantiomer is “left-handed” because it would advance into the page as you rotated it to the left. In contrast, [Co(NH3)6]3+has several symmetry planes and is achiral. (Only one of the symmetry planes is identified.)
Notes
 Enantiomers are isomers that are nonsuperimposable mirror images of one another. Locating a plane of symmetry within a molecule or complex means that the species is achiral and has no stereoisomers.
Keywords
 enantiomers
20-22
Title
 Structure of a polarimeter
Caption
 Figure 20.22 The essential features of a polarimeter. The polarimeter measures the angle through which the plane of plane-polarized light is rotated when the light is passed through a solution of a chiral substance.
Notes
 A polarimeter is an instrument used to measure the magnitude and direction of rotation of plane-polarized light by a chiral sample
Keywords
 chirality, optical isomers
20-22-01UN
Title
 Worked Example 20.9
Caption
 The possible diastereomers and enantiomers of [Co(en)2Cl2]+ion.
Notes
 Solution to Worked Example 20.9
Keywords
 stereoisomers
20-22-02UN
Title
 Key Concept Problem 20.11
Caption
 Consider the following ethylenediamine complexes of rhodium:
Notes
 Key Concept Problem 20.11
Keywords
 stereoisomers
20-25
Title
 Absorption spectrum
Caption
 Figure 20.25 (a) A solution that contains the [Ti(H2O)6]3+ion. (b) Visible absorption spectrum of the [Ti(H2O)6]3+ion.
Notes
 The color of a complex corresponds to wavelengths of light that are not absorbed by the complex. The observed color is usually the complement of the color absorbed. If all wavelengths of light are absorbed, a complex appears black. If no wavelengths of light are absorbed, a complex appears white (colorless).
Keywords
 absorption spectrum
20-26
Title
 The color of a substance
Caption
 Figure 20.26 Using an artist’s color wheel, we can determine the observed color of a substance from the color of the light absorbed. Complementary colors are shown on opposite sides of the color wheel, and an approximate wavelength range for each color is indicated. Observed and absorbed colors are generally complementary. For example, if a complex absorbs only red light of 720 nm wavelength, it has a green color.
Notes
 The color of a substance is usually the complement of the color absorbed by a substance
Keywords
 color, absorption spectrum
20-26-01UN
Title
 Valence bond theory
Caption
 The bonding in metal complexes arises when a filled ligand orbital containing a pair of electrons overlaps a vacant hybrid orbital on the metal ion to give a coordinate covalent bond.
Notes
 Valence bond theory applied to bonding in metal complexes
Keywords
 valence bond theory
20-26-02UN
Title
 Orbital diagram for Co2+
Caption
 A free Co2+ion has the electron configuration [Ar] 3d7, and its orbital diagram is:
Notes
 Orbital diagram for Co2+
Keywords
 bonding, valence bond theory
20-26-03UN
Title
 Orbital Diagram for [CoCl4]2--
Caption
 The orbital diagram represents the bonding in the complex, showing the hybridization of the metal orbitals (for the tetrahedral geometry) and the four pairs of ligand electrons, now shared in the bonds between the metal and the ligands:
Notes
 Orbital diagram for tetrahedral complex [CoCl4]2--
Keywords
 bonding, tetrahedral
20-26-04UN
Title
 Orbital diagram for Ni2+
Caption
 A free Ni2+ion has eight 3d electrons, two of which are unpaired in accord with Hund's rule.
Notes
 Orbital diagram for Ni2+
Keywords
 bonding
20-26-05UN
Title
 Orbital diagram for [Ni(CN)4]2-
Caption
 In square planar complexes, the metal uses a set of four hybrid orbitals called dsp2 hybrids, which point toward the four corners of a square.
Notes
 Although both have a coordination number of four, the metal ions in square planar and tetrahedral complexes require different hybrid orbitals because of the differences in the orientation of the ligands.
Keywords
 bonding, square planar
20-26-06UN
Title
 Orbital diagram for Co3+
Caption
 A free Co3+ion has six 3d electrons, four of which are unpaired.
Notes
 Orbital diagram for Co3+
Keywords
 bonding
20-26-07UN
Title
 Orbital diagram for [CoF6]3-
Caption
 The octahedral geometry of the [CoF6]3-ion requires sp3d2 hybrid orbitals.
Notes
 Orbital diagram for octahedral complex [CoF6]3-; this complex is referred to as a high-spin complex because the d electrons are arranged according to Hund's rule to give the maximum number of unpaired electrons.
Keywords
 bonding, octahedral, high-spin
20-26-08UN
Title
 Orbital diagram for [Co(CN)6]3-
Caption
 Since magnetic measurements of this complex indicate it is diamagnetic, the octahedral geometry is accomplished through a different set of hybrid orbitals called the d2sp3 hybrids.
Notes
 Orbital diagram for octahedral [Co(CN)6]3-; this complex is referred to as a low-spin complex since the d electrons are paired up to give a maximum number of doubly occupied d orbitals and a minimum number of unpaired electrons.
Keywords
 bonding, octahedral, low-spin
20-26-09
Title
 Worked Example 20.10
Caption
 Ball-and-stick model of the [V(NH3)6]3+ion.
Notes
 Structure of the [V(NH3)6]3+ion for Worked Example 20.10
Keywords
 valence bond theory
20-27
Title
 Octahedral crystal field model
Caption
 Figure 20.27 Crystal field model of the octahedral [TiF6]3-complex. The metal ion and ligands are regarded as charged particles held together by electrostatic attraction. The ligands lie along the ±x, ±y, and ±z directions.
Notes
 Crystal field theory is an electrostatic model. Valence bond theory is an orbital overlap model.
Keywords
 crystal field theory
20-28
Title
 The five d orbitals
Caption
 Figure 20.28 The shapes of the five d orbitals and their orientation with respect to an octahedral array of charged ligands.
Notes
 The lobes of the orbitals indicate regions of space where a d electron is most likely to be found
Keywords
 crystal field theory
20-29
Title
 Crystal field splitting
Caption
 Figure 20.29 A d-orbital energy level diagram for a free metal ion and a metal ion in an octahedral complex. In the absence of ligands, the five d orbitals have the same energy. When the metal ion is surrounded by an octahedral array of ligands, the d orbitals increase in energy and split into two sets that are separated in energy by the crystal field splitting, D. The d orbitals whose lobes point directly toward the ligands (dz2 and dx2 -y2) are higher in energy than the d orbitals whose lobes point between the ligands (dxy, dxz, and dyz).
Notes
 Crystal field splitting between two sets of d orbitals
Keywords
 crystal field splitting
20-29-01UN
Title
 Energy transitions in crystal field splitting
Caption
 When [Ti(H2O)6]3+absorbs blue-green light with a wavelength of about 500 nm, the absorbed energy promotes the d electron to one of the higher-energy orbitals.
Notes
 Energy transitions in crystal field splitting
Keywords
 crystal field splitting
20-29-02UN
Title
 Electronic transitions in crystal field splitting
Caption
 The absorption spectra of different complexes indicate that the size of the crystal field splitting depends on the nature of the ligands.
Notes
 The stronger the interaction between the ligand and a metal ion, the greater the crystal field splitting, D, and the higher the energy (and the lower the wavelength) of light absorbed by the complex.
Keywords
 crystal field splitting
20-29-03UN
Title
 The spectrochemical series
Caption
 In general, the crystal field splitting increases as the ligand varies in the following order, known as the spectrochemical series.
Notes
 The strong-field ligands CN-and CO are toxic to humans because of their strong interactions with iron in cytochrome oxidase and hemoglobin, respectively.
Keywords
 spectrochemical series
20-29-04UN
Title
 High spin versus low spin complexes
Caption
 Crystal field theory accounts for the magnetic properties of complexes as well as for their color. Complexes with weak-field ligands are high-spin, while complexes with strong-field ligands are low-spin.
Notes
 Crystal field theory correlates the relationship between weak-and strong-field ligands with high-and low-spin complexes, respectively.
Keywords
 crystal field theory
20-29-05UN
Title
 Worked Example 20.11
Caption
 The energy level diagrams for the three complexes of Example 20.11.
Notes
 Worked Example 20.11
Keywords
 crystal field theory
20-30
Title
 Tetrahedral and square planar complexes
Caption
 Figure 20.30 Energies of the d orbitals in tetrahedral and square planar complexes relative to their energy in the free metal ion. The crystal field splitting energy D is small in tetrahedral complexes but much larger in square planar complexes.
Notes
 Almost all tetrahedral complexes are high-spin, and square planar complexes are low-spin. Octahedral complexes can be either low-spin or high-spin.
Keywords
 crystal field splitting
20-30-01
Title
 Structures for Worked Example 20.12
Caption
 Ball-and-stick models of iron(III) tetrachloride and platinum(II) tetrachloride.
Notes
 Structures of iron(III) tetrachloride and platinum(II) tetrachloride for Worked Example 20.12
Keywords
 crystal field theory
20-30-02UN
Title
 Energy diagrams for Worked Example 20.12
Caption
 Energy-level diagrams for iron(III) tetrachloride (tetrahedral, high-spin) and platinum(II) tetrachloride (square planar, low-spin).
Notes
 Worked Example 20.12
Keywords
 crystal field theory
20-30-030UN
Title
 Key Concept Summary
Caption
 Transition elements and coordination chemistry key concept summary.
Notes
 Key Concept Summary for Chapter 20
Keywords
 key concept, summary
20-30-05UN
Title
 Key Concept Problem 20.19
Caption
 What is the general trend in the following properties from left to right across the first transition series? Explain each trend.
Notes
 Key Concept Problem 20.19
Keywords
 key concept, transition elements, periodicity
20-30-06UN
Title
 Key Concept Problem 20.20
Caption
 Classify the following ligands as monodentate, bidentate, or tridentate. Which can form chelate rings?
Notes
 Key Concept Problem 20.20
Keywords
 key concept, ligands
20-30-07UN
Title
 Key Concept Problem 20.22
Caption
 Consider the following isomers of [Cr(NH3)2Cl4]--.
Notes
 Key Concept Problem 20.22
Keywords
 isomers, enantiomers
20-30-08UN
Title
 Key Concept Problem 20.23
Caption
 Consider the following ethylenediamine complexes:
Notes
 Key Concept Problem 20.23
Keywords
 key concept, chirality
20-30-10UN
Title
 Key Concept Problem 20.25
Caption
 Imagine two complexes, one tetrahedral and one square planar, in which the central atom is bonded to four different ligands (shown here in four different colors). Is either complex chiral? Explain.
Notes
 Key Concept Problem 20.25
Keywords
 key concept, chirality
20-TB01
Title
 Table 20.1 Selected Properties of First-Series Transition Elements
Caption
Notes
Keywords
20-TB02
Title
 Table 20.2 Standard Potentials for Oxidation of First-Series Transition Metals
Caption
Notes
Keywords
20-TB03
Title
 Table 20.3 Chromium Species in Common Oxidation States
Caption
Notes
Keywords
20-TB04
Title
 Table 20.4 Examples of Complexes with Various Coordination Numbers
Caption
Notes
Keywords
20-TB05
Title
 Table 20.5 Names of Some Common Ligands
Caption
Notes
Keywords
20-TB06
Title
 Table 20.6 Names of Some Common Metallate Anions
Caption
Notes
Keywords
20-TB07
Title
 Table 20.7 Hybrid Orbitals for Common Coordination Geometries
Caption
Notes
Keywords
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