Week 12 - d-Block metal chemistry

Juniata College Practice Set for Week 12 - d-Block metal chemistry: General Considerations. Created 2026 for Inorganic Chemistry using slides from Dr. Baran

The d-block metals fill the _____ atomic orbitals progressively across periods ______ respectively.

3d, 4d, and 5d; 4, 5, and 6

Transition Metals Distinction

Have an incomplete d subshell in at least one oxidation state

D-Block Metals Distinction

Simply occupies the d-block of the periodic table (Includes Zn, Cd, and Hg which have full d^10 config.)

Minor Deviations of fillings occur (notably Cr ([Ar]3d⁵4s¹) and Cu ([Ar]3d¹⁰4s¹) ), why is this the case?

Due to the extra stability of half-filled and fully filled d subshells.

As metallic radii decreases from group 3 to 6-7, nuclear charge _____

Increases

As nuclear charge contracts orbitals, they start to _____

Remain relatively constant or slightly increase

Approaching group 12, the d subshell fills and electron-electron repulsion _____

Increases

Define Lanthanide Contraction

The steady, progressive decrease in the atomic and ionic radii of the lanthanide elements (lanthanum to lutetium) as their atomic number increases

Because of lanthanide contraction, the 4d and 5d metals have ______ radii

Similar

Define Standard enthalpies of atomization (ΔₐH°)

It reflects the strength of metallic bonding.

Standard enthalpies of atomization (ΔₐH°) pattern raise from group ___, peaks at around group ___, and falls towards group ___

1; 5-6; 12

The ΔₐH°of d10 configuration contributes ____ to metallic bonding

Little

Why does 4d and 5d metals generally have higher ΔₐH° than their 3d counterparts?

There’s greater spatial extent and better orbital overlap (5d–5d > 4d–4d > 3d–3d).

First ionization energies (IE₁) _____ ______ across the periodic table.

Increase gradually

IE₁ of d-block metals show what?

A slow, irregular rise with fluctuations

IE₁ of noble gasses show what?

Sharp Peaks

The 5d metals generally have ____ IE₁ than their 3d or 4d counterparts.

Higher

Standard reduction potentials (E°) for the M²⁺/M couple ____.

Vary widely

Most first-row d-block metals have ____ E° values

Negative

Negative E° values of first-row d-block metals mean what?

Meaning their M²⁺ ions are more easily reduced to the metal than H⁺ to H₂

The exception for the negative E° values of the first-row d-block metals is..?

Cu²⁺/Cu (+0.34 V)

What determines color from d-block compounds?

D-d electronic transitions

Characterize paramagnetic compounds

Paramagnetic compounds possess at least one unpaired electron

What is a transition metal complex

They consist of a Central atom that is neutral/ionic transition metal acting as a lewis acid. That central atom is surrounded by neutral molecules or ions(ligands) and forms coordination bonds.

Define Coordination Bonds

Ligands which form donor-acceptor bonds with central atoms via donor atoms

Characteristic properties of d-block elements that they exhibit in their compounds

1) Formation of coordination complexes; 2) Paramagnetism; 3) Variation of oxidation states; 4) Color of their compounds

When a compound absorbs a particular wavelength of visible light, what does it transmit?

The complimentary colour

Red is absorbed at ____

700-620nm

Orange is absorbed at ____

620-580nm

Yellow is absorbed at ____

580-560nm

Green is absorbed at ____ 560-490nm

Blue is absorbed at ____

490-430nm

Purple is absorbed at

430-380nm

Define denticity

The number of donor atoms

What is the name of 1 Denticity

Monodenate

What are examples of monodenates?

H2O, NH3, THF, Pyridine (py), Cl-, DMSO

What is the name of 2 Denticity

Bidentate

What are examples of bidentates?

en (1,2-ethanediamine), [acac]-, [ox]^2-, bpy, phen

What is the name of 3 Denticity

Tridentate

What is an example of tridentates?

dien (1,4,7-triazaheptane)

What is the name of 4 Denticity

Tetradenate

What is an example of tetradenate

trien (1,4,7,10-tetraazadecane)

What is the name of 6 Denticity

Hexadentate

What is an example of hexadenate?

[EDTA]^4-

In a complex structural diagram a line denotes what?

The bond between an anionic ligand and the metal

In a complex structural diagram, an arrow denotes what?

The donation of an electron pair from a neutral ligand

Sterically demanding ligands favor ____ coordination numbers at metal centers

Low

High coordination numbers are most likely to be attained with ____ ligands and ____ metal ions

Small; Large

Low coordination numbers will be favored by metals in ____ oxidation states with ____ ligands

High; π-bonding

CN number 2 has what geometry?

Linear

CN number 3 has what geometry? Commonly trigonal planar, Less commonly Trigonal pyramidal

CN number 4 has what geometry?

Tetrahedral; square planar (d8)

CN number 5 has what geometry?

Trigonal bipyramidal; square-based pyramidal

CN number 6 has what geometry?

Commonly octahedral, Less commonly trigonal prismatic

CN number 7 has what geometry?

Commonly pentagonal bipyramidal, Less commonly monocapped octahedron; monocapped trigonal prism

CN number 8 has what geometry?

Commonly square antiprismatic; dodecahedral; hexagonal bipyramidal, Less commonly cube; bicapped trigonal prism

CN number 9 has what geometry?

Tricapped trigonal prismatic

Kepert model

Treats ligand as point charges on the surface of a sphere centered on the metal, repelling each other

Are lone pairs of electrons considered for the Kepert model?

No, they are ignored

Are repulsions between ligands considered for the Kepert model?

Yes, geometry is dependent on the number of ligands for this reason

CN = 2 is restricted to what complexes?

Cu(I), Ag(I), Au(I), and Hg(II). Examples: [CuCl₂]⁻, [Ag(NH₃)₂]⁺, R₃PAuCl, [Hg(SMe)₂].

CN = 3 is _____

Uncommon; trigonal planar structures are seen with d¹⁰ metal centres: [Cu(CN)₃]²⁻, [Ag(PPh₃)₃]⁺, [Pt(PPh₃)₃].

CN = 4 is _____

Extremely common: tetrahedral (most metals), square planar (d⁸ metals: Pt²⁺, Pd²⁺, Au³⁺, Rh⁺, Ir⁺, Ni²⁺ with strong field), or "flattened" tetrahedral.

CN = 5 includes both _____ and _____ geometries and _____

trigonal bipyramidal; square pyramidal; everything in between. Examples: [Zn{N(CH₂CH₂NH₂)₃}Cl]⁺, [Cu(bpy){NH(CH₂CO₂)₂}].

CN = 6 gives the ________ _____ geometry.

Predominantly Octahedral; Some d⁰ and d¹ complexes (notably of early transition metals like Mo and W) adopt the trigonal prismatic arrangement.

CN = 7 gives what geometries?

Pentagonal bipyramidal, monocapped octahedral, or monocapped trigonal prismatic geometries. Examples: [TaCl₄(PMe₃)₃], [ZrF₇]⁻, [ScCl₂(15-crown-5)]₂[CuCl₄].

CN = 8 includes what geometries?

Square antiprism, dodecahedron, hexagonal bipyramid, and bicapped trigonal prism.

CN = 9 is found mainly in what complexes?

Y, La, and f-block elements.

Define the Electroneutrality Principle

The charge on a complex can be represented as distributed across the metal and its ligands in a way that gives each atom a formal charge close to zero.

Structural isomers have the same ____ but different ____

Molecular formula; Atom connectivity

Define Ionisation isomers

An anionic ligand inside the coordination sphere swaps with an anion outside. Example: [Co(NH₃)₅Br][SO₄] vs [Co(NH₃)₅(SO₄)]Br.

Define Hydration isomers

H₂O swaps between the first coordination sphere and outside. Example: [Cr(OH₂)₄Cl₂]Cl·2H₂O vs [Cr(OH₂)₅Cl]Cl₂·H₂O.

Define Coordination isomers

Ligands are exchanged between two different metal centres in a complex salt. Example: [Co(NH₃)₆][Cr(CN)₆] vs [Cr(NH₃)₆][Co(CN)₆].

Define Linkage isomers

An ambidentate ligand coordinates through different donor atoms. Example: [Co(NH₃)₅(NCS-N)]²⁺ vs [Co(NH₃)₅(NCS-S)]²⁺.

Stereoisomers have the same _____ but different ____

Connectivity; Spatial arrangements

Diastereoisomer examples are…:

cis/trans and mer/fac

In square planar MA₂B₂ complexes like [PtCl₂(NH₃)₂] the cis isomer has what?

Like groups adjacent (polar)

In square planar MA₂B₂ complexes like [PtCl₂(NH₃)₂] the trans isomer has what?

Like groups opposite (non-polar)

In octahedral MA₃B₃ complexes like [CrCl₃(H₂O)₃], the fac isomer has what?

(Facial) has three identical ligands on one triangular face

In octahedral MA₃B₃ complexes like [CrCl₃(H₂O)₃], the mer isomer has what?

(Meridional) has the three identical ligands in a T-shape

Define Enantiomer

Non-superposable mirror images (Λ and Δ forms)

Enantiomers occur in what complexes?

Tris-chelate octahedral complexes, like [Cr(acac)₃] and [Co(en)₃]³⁺.

The sequential replacement of water ligands by ligand L is described by ____

Stepwise stability constants K₁, K₂, … Kₙ.

The overall (cumulative) stability constant is:

β₂ = K₁ × K₂.

Stability constants quantify ____ of complexes in solution.

Thermodynamic stability

Define Chelate effect

Chelated complexes with bidentate or polydentate ligands are thermodynamically more stable than analogous complexes with the same number of comparable monodentate ligands.

Chelate effect is predominantly an ____ — by replacing multiple ____ ligands with one ____ ligand releases more molecules into solution.

Entropy effect; monodentate; polydentate

Using the chelate effect, which of these two are more stable? [Co(en)₃]³⁺ or [Co(NH₃)₆]³⁺

[Co(en)₃]³⁺ is much more stable than [Co(NH₃)₆]³⁺

Define chelate ring

the ring formed by metal + chelating ligand

Define bite angle

the L–M–L angle imposed by a bidentate ligand.

What does the HSAB principle stand for?

The Hard and Soft Acids and Bases

Define the HSAB principle

Hard acids preferentially bind hard bases, and soft acids preferentially bind soft bases.

Hart metal centres (class a) are?

Small, high oxidation state, and low polarizability. Examples: Li⁺, Na⁺, K⁺, Mg²⁺, Ca²⁺, Al³⁺, Cr³⁺, Fe³⁺, Co³⁺, Ti⁴⁺, Zr⁴⁺, [VO]²⁺.

Soft metal centres (class b) are?

Large, low/zero oxidation state, and high polarisability. Examples: Cu⁺, Ag⁺, Au⁺, Tl⁺, Hg²⁺, Cd²⁺, Pd²⁺, Pt²⁺, They have zero-valent metal centres.

Intermediate metal centres are?

Pb²⁺, Fe²⁺, Co²⁺, Ni²⁺, Cu²⁺, Os²⁺, Ru³⁺, Rh³⁺, Ir³⁺.

Hard ligand (class a) examples are?

F⁻, Cl⁻, H₂O, ROH, R₂O, [OH]⁻, [RCO₂]⁻, [CO₃]²⁻, [NO₃]⁻, [PO₄]³⁻, [SO₄]²⁻, NH₃, RNH₂.

Soft ligand (class b) examples are?

I⁻, H⁻, R⁻, [CN]⁻ (C-bound), CO (C-bound), RSH, R₂S, R₃P, R₃As, alkenes, arenes.

Intermediate ligand examples are?

Br⁻, [N₃]⁻, py, [SCN]⁻ (N-bound), ArNH₂, [NO₂]⁻.

Fe³⁺ (hard) has what log K₁ order?

F⁻ ≫ Cl⁻ > Br⁻

Hg²⁺ (soft) has what log K₁ order?

I⁻ ≫ Br⁻ > Cl⁻ > F⁻.