yr 1 structures of solids

6-coordinate MX₂, hcp, 2D

CdI₂

MgI₂, MgBr₂, MnI₂, MnBr₂

many TM diiodides and dibromides

6-coordinate MX₂, ccp, 2D

CdCl₂

MgCl₂, MnCl₂, FeCl₂

many TM dichlorides

8-coordinate MX₂, primitive

fluorite

CaF₂, BaF₂, HgF₂, SrCl₂

largest dications

8-coordinate MX, primitive

CsI

CsCl, CsBr, NH₄Cl

largest cations

6-coordinate MX₂, hcp, 3D

rutile

TiO₂, MnO₂, NbO₂, MnF₂, FeF₂, MgF₂

most TM dioxides, most TM difluorides

6-coordinate MX, hcp

NiAs

Ni, Fe, Co with S, Se: chalcogenides (covalency)

6-coordinate MX, ccp

rocksalt

extremely common:

NaCl, NaBr, KF, LiI etc.

MgO, CaS, MgSe etc. (not BeO)

MnO, FeO, TiO, VO (not ZnO)

4-coordinate MX, hcp

wurtzite: NH₄F, ZnS

CuBr, CuI (both large and polarisable for 3D)

BeO, ZnO (small dications - CN only 4)

GaN, GaP, InN

SiC, lonsdaleite

4-coordinate MX, ccp

zinc blende: ZnS, c-BN…

CuBr, CuI (both large and polarisable for 3D)

BeO, ZnO (small dications - CN only 4)

GaN, GaP, InN

SiC, diamond

4-coordinate M2X, ccp

antifluorite

Li₂O, Na₂O, Na₂S, K₂Se etc: group 1 chalcogenides

but not large polarisable cations (ie not Cs, Ag, Au)