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23 Transition Metals and Solutions to Exercises Coordination Chemistry (e) No, we do not expect carbonic anydrase to have a deep color like hemoglobin. The ion is a d¹⁰ metal center. Its d-orbitals are completely occupied and there is no possibility for the d-d transitions that lead to colored complexes. 23.91 (a) Both compounds have the same general formulation, so Co is in the same (+3) oxidation state in both complexes. (b) Cobalt(III) complexes are generally inert; that is, they do not rapidly exchange ligands inside the coordination sphere. Therefore, the ions that form precipitates in these two cases are probably outside the coordination sphere. The dark violet compound A forms a precipitate with BaCl₂(aq) but not AgNO₃(aq), so it has outside the coordination sphere and coordinated Br-, [Co(NH₃)₅ The red-violet compound B forms a precipitate with AgNO₃(aq) but not BaCl₂(aq) so it has Br- outside the coordination sphere and coordinated [Co(NH₃)₅SO₄]Br. Compound A, dark violet Compound B, red-violet NH₃ 2+ + NH₃ NH₃ Co Co Br⁻ NH₃ Br NH₃ SO₄ NH₃ (c) Compounds A and B have the same formula but different properties (color, chemical reactivity), so they are isomers. They vary by which ion is inside the coordination sphere, so they are coordination sphere isomers. (d) Compound A is an ionic sulfate and compound B is an ionic bromide, so both are strong electrolytes. According to the solubility rules in Table 4.1, both should be water-soluble. 23.92 Determine the empirical formula of the complex, assuming the remaining mass is due to oxygen, and a 100 g sample. 1 mol Mn 10.0 g Mn = 0.1820 mol Mn; 0.182 / 0.182 = 1 54.94 1 mol K = 0.7315 mol K; 0.732 / 0.182 = 4 K = 0.7327 mol C; / 0.182 = 4 1 mol Br 29.2 g Br = 0.3654 mol Br; 0.365 / 0.182 = 2 Br = 1.463 mol O; 1.46 / 0.182 = 8 There are 2 C and 4 per oxalate ion, for a total of two oxalate ligands in the complex. To match the conductivity of K₄[Fe(CN)₆], the oxalate and bromide ions must be in the coordination sphere of the complex anion. Thus, the compound is K₄[Mn(ox)₂Br₂]. 715