all ine ▁framework ▁of ▁a ▁metal ▁complex ▁or ▁a ▁salt , ▁which ▁is ▁not ▁directly ▁bond ed ▁to ▁the ▁metal ▁c ation . ▁ ▁Upon ▁cry st all ization ▁from ▁water ▁or ▁mo ist ▁sol vent s , ▁many ▁comp ounds ▁incorpor ate ▁water ▁mole cules ▁in ▁their ▁cry st all ine ▁frameworks . ▁Water ▁of ▁cry st all ization ▁can ▁generally ▁be ▁removed ▁by ▁he ating ▁a ▁sample ▁but ▁the ▁cry st all ine ▁properties ▁are ▁often ▁lost . ▁ ▁For ▁example , ▁in ▁the ▁case ▁of ▁sod ium ▁ch lor ide , ▁the ▁di h yd rate ▁is ▁un stable ▁at ▁room ▁temperature . ▁ ▁Comp ared ▁to ▁in organ ic ▁sal ts , ▁prote ins ▁cry st all ize ▁with ▁large ▁amounts ▁of ▁water ▁in ▁the ▁cry stal ▁lattice . ▁A ▁water ▁content ▁of ▁ 5 0 % ▁is ▁not ▁un common ▁for ▁prote ins . ▁ ▁N omen cl ature ▁ ▁In ▁mole cular ▁formulas ▁water ▁of ▁cry st all ization ▁is ▁indicated ▁in ▁various ▁ways , ▁but ▁is ▁often ▁vague . ▁The ▁terms ▁hyd r ated ▁comp ound ▁and ▁hyd rate ▁are ▁generally ▁v agu ely ▁defined . ▁ ▁Position ▁in ▁the ▁cry stal ▁structure ▁▁ ▁A ▁salt ▁with ▁associated ▁water ▁of ▁cry st all ization ▁is ▁known ▁as ▁a ▁hyd rate . ▁ ▁The ▁structure ▁of ▁hyd r ates ▁can ▁be ▁quite ▁elaborate , ▁because ▁of ▁the ▁existence ▁of ▁hydro gen ▁b onds ▁that ▁define ▁polym er ic ▁structures . ▁ ▁Histor ically , ▁the ▁structures ▁of