Practice Problems: Transition Elements and Coordination Chemistry 1. Complete the valence level orbital notation for the following monatomic ions. KEY CHEM 1B a) Ag + b) Co 3+ 4d 5s 3d 4s c) Fe 3+ d) Cr 3+ 3d 4s 3d 4s 2. For each of the following complexes, determine the number of ligands and the coordination number and oxidation number of the central metal. [Mn(EDTA)] 2 # Ligands Coordination # Oxidation # 1 6 +2 [Co(en) 2 (NH 3 )CN] 2+ Pt(NH 3 ) 2 Cl 2 4 6 +3 4 4 +2 3. Give the ligand name for each of the following ligands. Donor atom(s) are written in bold. The bottom three in the third column are common abbreviations rather than formulas. H 2 O aqua 2 C 2 O 4 oxalato CN cyano F fluoro NH 3 ammine SCN thiocyanato Cl chloro NO 2 nitro NCS isothiocyanato Br bromo ONO nitrito en ethylenediamine I iodo OH hydroxo gly glycinato CO 3 2 carbonato CO carbonyl EDTA 4 ethylenediaminetetraacetato 4. Circle the ligands above that would require the use of the bis-, tris-, or tetrakis- numeric prefixes in the naming of the complex. Explain why below: Bis-, tris-, tetrakis-, pentakis-, etc. are used with parentheses around the ligand name when the name of the ligand already contains a common numeric prefix (mono-, di-, tri-, etc.), like in ethylenediamine and ethylenediaminetetraacetate. They are also used if the ligand is polydentate, which applies to all four of the circled ligands. Note: Since EDTA 4 is a hexadentate ligand, it is unlikely that more than one will complex the same metal center, making the use of these prefixes less likely for EDTA 4.
5. Name the following complex cations, neutral complexes, and complex anions. ethylenediaminetetraacetato- [Cr(H 2 O) 5 Cl] 2+ pentaaquachlorochromium(iii) ion [Fe(EDTA)] ferrate(iii) ion bis(ethylenediamine)dithiocyanatoplatinum(iv) [Pt(en) 2 (SCN) 2 ] 2+ ion [Co(CO 3 ) 3 ] 3 tricarbonatocobaltate(iii) ion diamminebis(oxalato)chromate(iii) [Co(NH 3 ) 5 (NO 2 )] 2+ pentaamminenitrocobalt(iii) ion [Cr(NH 3 ) 2 (C 2 O 4 ) 2 ] ion [Co(en) 3 ] 3+ tris(ethylenediamine)cobalt(iii) ion [Co(NCS) 4 ] 2 tetraisothiocyanatocobaltate(ii) ion Ni(CO) 4 tetracarbonylnickel(0) [Fe(CN) 6 ] 4 hexacyanoferrate(ii) ion 6. Name the following coordination compounds. [Co(NH 3 ) 5 (ONO)]SO 4 pentaamminenitritocobalt(iii) sulfate [Ag(NH 3 ) 2 ][Ag(CN) 2 ] diamminesilver(i) dicyanoargentate(i) tetraamminedibromocobalt(iii) [Co(NH 3 ) 4 Br 2 ]Br bromide K 3 [Fe(C 2 O 4 ) 3 ] potassium tris(oxalato)ferrate(iii) 7. Matching: Match the descriptions below with the letter of a type of isomer on the left. Each letter can be used more than once or not at all. A = Structural Isomers B = Coordination Isomers C = Linkage Isomers D = Stereoisomers E = Geometric Isomers F = Optical Isomers A general category for isomers with different bonds D general category for isomers with the same bonds arranged in different locations F isomers with chiral centers E cis- and trans- isomers F isomers that rotate plane polarized light C isomers that have functional groups bonded through different atoms B isomers that have the same atoms bonded, but bonded in a different way E isomers that occur as the result of rigid bonds 8. Draw condensed structures for 2-propanol, 2-butanol, and 2-butanone. Mark any chiral carbons with an asterisk. OH CH 3 CHCH 3 2-propanol OH CH 3 CHCH 2 CH 3 * 2-butanol O CH 3 CCH 2 CH 3 2-butanone
9. The crystal field splitting energy of a complex is 2.9 x 10 19 J. 680 nm a) What wavelength of light (in nm) would be absorbed for this d-d electronic transition? red b) To what color of light does this wave length correspond? green c) What color would a solution of this complex appear? E electron = E photon = hc 2.9 x 10 19 J = (6.626 x 10 34 J s)(2.998 x 10 8 m/s) = 6.849913103 x 10 7 m 1 nm 10 9 m = 680 nm 10. Determine the following for the complex ion: [Cu(en) 3 ] 2+ a) What type of d-electron complex is it (for example: d 0, d 1, d 2, etc.)? d 9 b) Is the ligand a strong field ligand or a weak field ligand (circle one)? c) Would you expect the complex to be high spin or low spin (circle one)? d) On which piece of information, a) or b) (circle one), did you base your answer for Part c)? e) What is the hybridization of the central metal? sp 3 d 2 f) Fill in the valence level orbital notation below, circle the electrons that come from the ligands. 3d 4s 4p 4d 11. Label each orbital with the appropriate d-orbital designation (below the orbital). d yz d xz d xy d x 2 y2 d z 2
12. Label each orbital in the octahedral complex with the appropriate d-orbital designation (below the orbital). For the complex [CoF 6 ] 3 : a) Is o relatively large or small (circle one)? > b) How do the values of the splitting and the e pairing energies compare? Circle one: o = P c) Is the complex high spin or low spin (circle one)? < d) Fill in the valence electrons from the metal in both the isolated ion and the complex. d x 2 y2 d z 2 o d xy d xz d yz d-orbitals in isolated atom/ion d-orbitals in the complex e) Fill in the valence level orbital notation below, circle the electrons that come from the ligands. 3d 4s 4p 4d f) What is the hybridization of the orbitals on the central metal ion? sp 3 d 2 g) Based on the orbital notation in Part e) above, would you expect the complex to be paramagnetic or diamagnetic (circle one)?
13. For the complex [Co(CN) 6 ] 3 : a) Is o relatively large or small (circle one)? > b) How do the values of the splitting and the e pairing energies compare? Circle one: o = P c) Is the complex high spin or low spin (circle one)? < d) Fill in the valence electrons from the metal in both the isolated ion and the complex. o d-orbitals in isolated atom/ion d-orbitals in the complex e) Fill in the valence level orbital notation below, circle the electrons that come from the ligands. 3d 4s 4p 4d f) What is the hybridization of the orbitals on the central metal ion? d 2 sp 3 g) Based on the orbital notation in Part e) above, would you expect the complex to be paramagnetic or diamagnetic (circle one)?
14. For each of the following d-orbital splitting patterns, label each orbital with the appropriate d- orbital designation (below the orbital), and fill in the missing information. d xy d xz d yz d x 2 y2 d z 2 t d x 2 y2 d xy d z 2 o d xz d yz Geometry: tetrahedral square planar is generally: large or small large or small Spin is generally: high or low high or low Hybridization: sp 3 dsp 2 15. Fill in the valence level orbital notation below for the complex: [Pt(NH 3 ) 4 ] 2+ (square planar) 5d 6s 6p 16. Fill in the valence level orbital notation below for the complex: [MnCl 4 ] 2 (tetrahedral) 3d 4s 4p