Organometallic Solutions: #15
15.* (1993 2 3) A. Which of the following is rouge and which is colorless? TiO2 and Fe2O3 Color in transition metal complexes is usually the result of d–d* transitions:
TiO2 has Ti4+. It is therefore d0. Because it has no d electrons, there can be no d–d* transitions, and TiO2 is colorless. (In fact, it's actually used as a white pigment in paint, toothpaste, and sunscreen.) Fe2O3 has Fe3+. It's d5. Because it has d electrons, it can undergo d–d* transitions, and is rouge. It's a component of rust. B. Which of the following is more stable towards thermal decomposition? trans-Pt(PPh3)2R2: R= -CH2-C(CH3)3 or R = -CH2-CH(CH3)2 •For R= -CH2-C(CH3)3 there are no b-hydrogens, so there is no b-hydrogen elimination.•For R = -CH2-CH(CH3)2 there is one b-hydrogen, so there is b-hydrogen elimination.•Therefore, R= -CH2-C(CH3)3 is more stable towards thermal deocomposition. |
