I 1. The ionic radius of Cat and o--are 100pm and 140pm, respectively. (12 points) 1)Which kind of coordination polyhedra does calcium oxide belong to? 2) If adjacent Ca?+ and O- spherical ions are touching, calculate the edge length of the unit cell 3) Calculate the density for this solid 12. The valence electron configuration of gold is 5d6s. Recent stud ies show that the onding property of gold is quite similar to hydrogen. Please using Huckel molecular-orbital theory to determine whether the gold trimer cation(Au3)is a stable molecule or not. If it is stable, please tell the most stable structure of the cation(12 points) 13. Both CO and H,o molecules can be used as ligands. It is found that iron atom can coordinate five CO molecules to form Fe(CO)5, which is quite stable. However, no stable Fe(H2O)5 molecule has been observed. Why? (6 3) 14. What different point groups may the biphenyl molecule belong to, depend ing on the rotational relationship of the two rings about the central C-C bond? Consider the same question for ferrocene(6 points) 15. For a bent AB2 molecule, taking the p orbital perpendicular to the molecular plane of each B atom as bases, work out the symmetry-adapted linear combination orbitals using projection operators(8 points) EC20(x-)O,(z) B y,R11. The ionic radius of Ca++ and O2- are 100pm and 140pm, respectively. (12 points) 1) Which kind of coordination polyhedra does calcium oxide belong to? 2) If adjacent Ca2+ and O2- spherical ions are touching, calculate the edge length of the unit cell; 3) Calculate the density for this solid. 12. The valence electron configuration of gold is 5d106s1 . Recent studies show that the bonding property of gold is quite similar to hydrogen. Please using Huckel molecular-orbital theory to determine whether the gold trimer cation (Au3 + ) is a stable molecule or not. If it is stable, please tell the most stable structure of the cation. (12 points) 13. Both CO and H2O molecules can be used as ligands. It is found that iron atom can coordinate five CO molecules to form Fe(CO)5, which is quite stable. However, no stable Fe(H2O)5 molecule has been observed. Why?(6 分) 14. What different point groups may the biphenyl molecule belong to, depending on the rotational relationship of the two rings about the central C-C bond? Consider the same question for ferrocene. (6 points) 15. For a bent AB2 molecule, taking the p orbital perpendicular to the molecular plane of each B atom as bases, work out the symmetry-adapted linear combination orbitals using projection operators (8 points). C2v E C2 σv (xz) '  v (yz) A 1 1 1 1 z , x2 , y2 ,z2 A2 1 1 -1 -1 Rz xy B1 1 -1 1 -1 x,Ry xz B2 1 -1 -1 1 y ,Rx yz