Mixed Lithium Magnesium Aryl Oxides Derived from Cresol: Crystal Structures and Solution NMR Studies of an Unexpected, Magnesium-Rich Oxo Product with a Trigonal Bipyramidal LiMg4 Cage and an Expected Lithium-Rich Product with a More Familiar Li.cntdot..cntdot..cntdot.Mg.cntdot..cntdot..cntdot.Li Chain