This quantity is measured for an NCE ligand (“LIG-und”) to determine the state of spin-crossover iron complexes, since it increases by 10 percent upon excitation. The Fourier (“FOR-ee-ay”) transform of the gas-phase molecular intensity curve is a histogram plotting this quantity, which is also the first peak in a crystal’s pair distribution function. It’s not a reaction rate, but due to trans influence, this quantity increases for ligands opposite sigma acceptors in square planar complexes. Mono·clinic crystals have three different values for this quantity labeled a, b, and c. Without pseudo·rotation, this quantity is greater for apical than equatorial ligands in trigonal bi·pyramidal complexes. Conversely, two distinct values for this quantity are measured on octa·hedral copper complexes because of a Jahn (“yahn”)–Teller distortion. For 10 points, a crystal’s lattice constant is analogous to what quantity, which is usually about an angstrom? ■END■
ANSWER: metal-ligand bond length [or bond distance; or bond radius; or interatomic spacing; or interatomic distance; accept lattice parameter or lattice constant until “lattice” is read; prompt on length, distance, radius, or spacing; prompt on a until read; prompt on d; prompt on r]
<Chemistry>
= Average correct buzz position