3-35. Two important idealized geometries for seven coordination are the monocapped trigonal prism (a) and the pentagonal bipyramid (b). The sevencoordinate complex Mo(CN)74 has been examined both as solid K4Mo(CN)72H2O and in aqueous solution. In the CN stretching region the ir spectrum has bands at 2119,2115,2090,2080,2074. and 2059cm for the solid and at 2080 and 2040cm ' for solutions. How many Raman and infrared bands would you expect for each geometry above and how many coincidences (bands present in both the ir and Raman spectra) should there be for each geometry? How do you interpret these data? 3-36. (a) Determine the number and activities of the carbonyl stretching modes of both the cis and trans isomers of L2M(CO)4. (b) Fe(CO)4Cl2 has ir bands at 2167,2126 , and 2082cm1 in CHCl3 solution. How would you interpret this spectrum? (c) Draw a picture of each carbonyl stretching symmetry coordinate of each isomer of L2M(CO)4. As an example of what we are looking for, the modes of mer- L3M(CO)3 are drawn below. The symbol stands for bond stretching and the symbol denotes bond compression. Note that the stretching of a unique chemical bond, as in the center diagram below, is always a legitimate basis for a symmetry coordinate. 3-37. Show that all of the CnHn hydrocarbons below have just a single ir active CH stretching mode