hem. 451 (Spring, 2005) Final Exam (100 pts) Name: --------------------------------------------------------, Student lid #: ----------------------, May 7, 2005 LAST, First ircle the alphabet segment of your Last Name: A-G H-L M-P Q-Z Please answer the following questions: Part I: Multiple hoices (21 pts: 7 @ 3 pts). Please circle the NE best answer: 1. Which of the following complexes one would expect to be labile? a) [o(nh 3 ) 5 (N 2 )] 2+ b) cis-pt(nh 3 ) 2 l 2 c) [r(en) 3 ]l 2 d) [r(n) 6 ] 3-2. Which of the following species does not obey the 18-e rule? a) (η 5-5 H 5 )Rh(η 2-2 H 4 )(PMe 3 ) b) [(η 5 -p)() 2 Ru-Ru(η 5 -p)() 2 ] c) Ho() 3 d) [HFe() 4 ] - 3. What is the IUPA name of the complex [u(nh 3 ) 4 ][Ptl 4 ] a) Tetraaminecopper(II) tetrachloroplatinate(iv) b) Tetraaminecopper(II) tetrachloroplatinate(ii) c) Tetraaminecopper(II) tetrachloroplatinum(ii) d) Tetraaminocopper(II) tetrachloroplatinate(ii) 4. What is the point group of cis-difluorotetraaminecobalt(iii) ion? a) D 4h b) Td c) 2v d) 2h 5. onsider the molecules and ions: I) [ol 4 ] 2- II) SF 4 III) XeF 4 IV) Ni() 5 Which of these species belong to the point group 4v? a) only II b) II and III c) I, II and III d) only IV 6. Which of the following species is expected to diamagnetic? a) [V(H 2 ) 6 ] 2+ b) [Fe( 2 4 ) 3 ] 4- c) [ol 4 ] 2- d) [Fe(N) 6 ] 3-7. Arrange the following complex ions in order of decreasing oct (largest oct = 1 & smalles oct = 4): [of 6 ] 3-, [of 6 ] 4-, [Rh(H 2 ) 6 ] 3+ and [Rh(N) 6 ] 3- a) [Rh(H 2 ) 6 ] 3+ > [Rh(N) 6 ] 3- > [of 6 ] 3- > [of 6 ] 4- b) [of 6 ] 4- > [of 6 ] 3- > [Rh(H 2 ) 6 ] 3+ > [Rh(N) 6 ] 3- c) [Rh(N) 6 ] 3- > [Rh(H 2 ) 6 ] 3+ > [of 6 ] 3- > [of 6 ] 4- d) [Rh(N) 6 ] 3- > [of 6 ] 3- > [Rh(H 2 ) 6 ] 3+ > [of 6 ] 4-1
Part II. (26 pts) oordination hemistry 1. (4 pts) Write the structural formula for tetraamminechromium(iii)-µ-amido-µ-hydroxobis(ethylenediamine)iron(iii) sulfate 2. (4 pts) Sketch all possible geometrical isomers for [o( 2 4 ) 2 l 2 ] + ion ( 2 4 2- = oxalate ion), and then indicate which of these complexes would exhibit optical activity. 3. (18 pts) Rationalize for the following observations: a) (5 pts) Diamagnetic compounds of cobalt(iii) such as [o(nh 3 ) 6 ] 3+ and [o(n 2 ) 6 ] 3- are orange-yellow. In contrast, the paramagnetic complexes [of 6 ] 3- and [o(h 2 ) 3 F 3 ] are blue. 2
b) (5 pts) The visible spectra of [Ni(NH 3 ) 6 ] 2+ and [Ni(H 2 ) 6 ] 2+ give the same number of bands but at different positions (sketch a graph to explain your answer showing how many bands you expect to find). c) (5 pts) A complex of nickel(ii), [Nil 2 (PPh 3 ) 2 ] is paramagnetic with a magnetic moment value µ = 2.96 BM. The analogous complex of palladium(ii) is diamagnetic (µ = 0). Include diagrams showing the molecular geometry and d-orbital energy levels for each complex ion as part of your answer d) (3 pts) The color of trans-[o(en) 2 l 2 ] + is less intense than that of cis-[o(en) 2 l 2 ] +. 3
Part III. (17 pts) rganometallic ompounds 1. (5 pts) Show the structural (show all bonds clearly) for () 3 Fe( 8 H 8 )Fe() 3, where 8 H 8 = cycloctatetraene. 2. (12 pts: 2 @ 6 pts each) Rationalize for the following observations: a) n going from Fe() 5 to Fe() 3 (PPh 3 ) 2, absorptions in the IR spectrum at 2025 cm -1 are replaced by bands at 1944, 1886 and 1881 cm -1. b) The reaction of (η 5 -p)fe() 2 Br with Na[o() 4 ] gave [(η 5 -p)()fe(µ-) 2 o() 3 ] in which an Fe-o bond does exist. Solely on the basis of the 18 e-rule explain your answer. 4
Part IV. (20 pts) Bioinorganic hemistry: 1. (6 pts) The precise mechanism of cis-platin anticancer is uncertain. However, several possibilities have been identified that it includes blocking of DNA replication. Discuss one of these possible mechanisms. 5
2. (6 pts) is-platin shows several prominent side H effects that include kidney and gastrointestinal 3 N H H 2 N Pt 2 problems and nausea. These arise as a result of the Pt H 3 N high dosage required and reactivity with a variety 3 S H 2 N of other biomolecules including inhibition of arboplatin Spiroplatin enzymes. To counteract these effects, second generation of Pt-drugs, such as those shown above have been developed that show similar therapeutic activities but at a lower dosages. What structure and chemical characteristics of these molecules can be used to rationalize their enhanced therapeutic properties? 6
3. (8 pts) a) Do you expect 2 to be a weak or strong ligand field? b) Recall that deoxygenated myoglobin (Mb) is high spin, while Mb 2 is low-spin. Is this consistent to part (a)? If not explain the inconsistency. c) What prevents simple iron porphyrins from functioning as 2 -carrier? d) Briefly explain the role of the peptide portion of hemoglobin in preventing the irreversible oxidation of Fe 2+? 7
Part V. (16 pts) Transition Metals: 1. (10 pts) Explain the following observations: a) Aqueous solutions of r 2+ are rapidly oxidized in air, as are solutions of Fe 2+, though more slowly, whereas the aqueous solutions of the intervening ion, Mn 2+ should be stable towards aerobic oxidation. b) The uniformity in the properties of the lanthanides and the great diversity observed in the chemistry of actinides. 8
2. (6 pts) Predict the probable structure (bond order & electron configuration and magnetic properties) for the following metal-metal bonded tetragonal-prismatic complexes: a) [r 2 (µ- 2 Me) 4 ] b) [Rh 2 (µ- 2 Me) 4 (H 2 ) 2 ] H 3 H 3 H 3 H 3 r? r H 2 Rh? Rh H 2 H 3 H 3 H 3 H 3 9
HEM 451- Spring-2005 FINAL EXAM You will have 140 minutes to complete this exam. The exam has 9 pages plus Periodic Table When you are told to do so, tear off the Periodic Table cover sheet and use as required during exam. 1 2 3 4 5 6 7 1 H 1.01 3 Li 6.94 11 Na 22.99 19 K 39.1 37 Rb 85.47 55 s 132.9 87 Fr (223) 4 Be 9.01 12 Mg 24.30 20 a 40.08 38 Sr 87.62 56 Ba 137.3 88 Ra 226.0 Periodic Table of the Elements 21 Sc 44.96 39 Y 88.91 57 La 138.9 89 Ac 227.0 22 Ti 47.88 40 Zr 91.22 72 Hf 178.5 104 Rf (261) 23 V 50.94 41 Nb 92.91 73 Ta 181.0 105 Db (262) 24 r 52.00 42 Mo 95.94 74 W 183.8 106 Sg (263) 25 Mn 54.94 43 Tc (98) 75 Re 186.2 107 Bh (262) 26 Fe 55.85 44 Ru 101.1 76 s 190.2 108 Hs (265) 27 o 58.93 45 Rh 102.9 77 Ir 192.2 109 Mt (266) 28 Ni 58.69 46 Pd 106.4 78 Pt 195.1 110 Uun (269) 29 u 63.55 47 Ag 107.9 79 Au 197.0 111 Uuu (272) 30 Zn 65.38 48 d 112.4 80 Hg 200.6 112 Uub (277) 5 B 10.81 13 Al 26.98 31 Ga 69.72 49 In 114.8 81 Tl 204.4 6 12.01 14 Si 28.08 32 Ge 72.59 50 Sn 118.7 82 Pb 207.2 7 N 14.01 15 P 30.97 33 As 74.92 51 Sb 121.8 83 Bi 209.0 8 16.00 16 S 32.06 34 Se 78.96 52 Te 127.6 84 Po (209) 9 F 19.00 17 l 35.45 35 Br 79.90 53 I 126.9 85 At (210) 2 He 4.00 10 Ne 20.18 18 Ar 39.95 36 Kr 83.80 54 Xe 131.1 86 Rn (222) 58 e 140.1 90 Th 232.0 59 Pr 140.9 91 Pa 231.0 60 Nd 144.2 92 U 238.0 61 Pm (145) 93 Np 237.0 62 Sm 150.4 94 Pu (244) 63 Eu 152.0 95 Am (243) 64 Gd 157.2 96 m (247) 65 Tb 158.9 97 Bk (247) 66 Dy 162.5 98 f (251) 67 Ho 164.9 99 Es (252) 68 Er 167.3 100 Fm (257) 69 Tm 168.9 101 Md (258) 70 Yb 173.0 102 No (259) 71 Lu 175.0 103 Lr (260) 10
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