Structures with high Z'

The table below contains details of all the structures with Z' >= 12 in the Cambridge Structural Database. As well as the name, journal reference and CSD Refcode there is a "Notes" section for each structure noting anything of interest about the packing or composition of the asymmetric unit, as well as links to polymorphs, redeterminations or similar structures. If you have anything to add or spot any errors then please let us know.

Z' Compound name


No 3D coordinates. Authors note that the structure was indexed in an orthorhombic cell but has been refined in P1

L. Fabian, A. Kalman, G. Argay, G. Bernath, Z. Cs. Gyarmati, Chem. Commun., 2004, 2114 ABUDAD02 2004

Cyclopropanecarboxylic acid isonicotinamide

Centrosymmetric isonicotinamide dimers terminated by hydrogen bonding to the cyclopropane carboxylic acid. The cyclopropyl group renders the assembly non-planar and imparts a dumbell shape. The high Z' seems to arise from the stacking of these dumbells in such a way as to accomodate the cycloproply substituents. The 'awkward' shape of the assembly is reminiscent of the 'wheel-and-axel' host design paradigm.

A. Lemmerer, M. A. Fernandes, New J. Chem., 2012, 36, 2242 ACOMOW 2012

bis(η5-Pentamethylcyclopentadienyl)-iron trifluoromethanesulfonate

Superstructure low temperature phase in P1 derived from high symmetry Z' = 0.5 high temperature form in Pmn21. The authors state that "the superstructure originates from the different conformers of the cations and canting of the OTf anions. The conformational differences among the cations as well as the polar orientation of the anion resulted in the non-centrosymmetric space group."

S. Hamada, Y. Funasako, T. Mochida, D. Kuwahara, K. Yoza, J. Organomet. Chem., 2012, 713, 35 DECYAN01 2012

4-(3,5-dichlorophenyl)-1,2,3,5-dithiadiazolyl radical

cis-cofacial π*–π* dimers with intra-dimer S⋯S contacts in the range 3.1–3.3 Å.

C.P.Constantinides, D.J.Eisler, A.Alberola, E.Carter, D.M.Murphy, J.M.Rawson, CrystEngComm, 2014, 16, 7298 DIXNEF 2014


Stacked Pt…Pt dimers with falt and bulky regions. The paper referenced concerns trans-[Co(NCNMe2)2(H2O)4]X2 2H2O. Error?

E.V.Andrusenko, A.S.Novikov, G.L.Starova, N.A.Bokach, Inorg.Chim.Acta, 2016, 447, 142 EYONEN 2016


High temperature alpha polymorph

A. S. Batsanov, J. C. Collings, R. M. Ward, A. E. Goeta, L. Porres, A. Beeby, J. A. K. Howard, J. W. Steed, T. B. Marder, CrystEngComm, 2006, 8, 622 GENLAN 2006


Low temperature beta polymorph

A. S. Batsanov, J. C. Collings, R. M. Ward, A. E. Goeta, L. Porres, A. Beeby, J. A. K. Howard, J. W. Steed, T. B. Marder, CrystEngComm, 2006, 8, 622 GENLAN01 2006

Triphenylmethanaminium anthracene-2-sulfonate mesitylene solvate

A salt with included mesitylene with a porous diamondoid architecture, exhibiting small distortions in the π-π stacking arrangement.

A. Yamamoto, S. Uehara, T. Hamada, M. Miyata, I. Hisaki, N. Tohnai, Cryst. Growth Des., 2012, 12, 4600 HEBGOM 2012

Triphenylmethanaminium anthracene-2-sulfonate mesitylene solvate


A. Yamamoto, S. Uehara, T. Hamada, M. Miyata, I. Hisaki, N. Tohnai, Cryst. Growth Des., 2012, 12, 4600 HEBGOM01 2012

Triphenylmethanaminium anthracene-2-sulfonate mesitylene solvate


A. Yamamoto, T. Hamada, I. Hisaki, M. Miyata, N. Tohnai, Angew. Chem., Int. Ed., 2013, 52, 1709 HEBGOM02 2013


Z' = 2 (HEYHUO03) and Z' = 4 (HEYHUO01) polymorphs also known

V. S. S. Kumar, A. Addlagatta, A. Nangia, W. T. Robinson, C. K. Broder, R. Mondal, I. R. Evans, J. A. K. Howard, F. H. Allen, Angew. Chem., Int. Ed., 2002, 41, 3848 HEYHUO02 2002


Tilted / modulated hydrogen bonded chain, rigid molecule.

A.Lozynskyi, S.Golota, B.Zimenkovsky, D.Atamanyuk, A.Gzella, R.Lesyk, Phosphorus,Sulfur,Silicon,Relat.Elem., 2016, 191, 1245 IVUBUY 2016

bis(4-(pyrrolidin-1-yl)pyridine)-silver nitrate hemihydrate

Cylindrical arrangement with half of the nitrates bridging between cylinders, and disordered water and the remaining nitrate ions inside the cylinders. The authors provide an interesting analysis in which the structure is described as intertwined three-connected networks, as each silver complex connects to two other complexes through –CH2–CH2–⋯–CH2–CH2– “embraces” and to one other complex through bridging nitrate anions. The topology of these 3D-nets is the common srs net (the (10,3)-a (Wells) or SrSi2 net.

M.A.M.Abu-Youssef, S.M.Soliman, M.M.Sharaf, J.H.Albering, L.Ohrstrom, CrystEngComm, 2016, 18, 1883 LALZIK 2016


Low temperature form. Undergoes phase transition at 195.8 K to Z' = 1 form (LANXOO)

L. Dobrzycki, T. Zielinski, J. Jurczak, K. Wozniak, J. Phys. Org. Chem., 2005, 18, 864 LANXOO02 2005


Independent molecules are conformationally different

M. Stadler, J. Bitzer, A. Mayer-Bartschmid, H. Muller, J. Benet-Buchholz, F. Gantner, H. -V. Tichy, P. Reinemer, K. B. Bacon, J. Nat. Prod., 2007, 70, 246 LEZQUD 2007


Pharmaceutical Ciclopirox. There are Z' = 12 and Z' = 1 forms along with kinetic, transient intermediate disordered forms. The reversible transitions involve a subtle compromise between phenomena related to molecular disorder, cooperative release of strains induced by cooling, and structural reorganization associated with topotactic changes in crystal lattice and symmetry.

C.Brandel, Y.Cartigny, N.Couvrat, M.Ermelinda S.Eusebio, Joao Canotilho, S.Petit, G.Coquerel, Chem.Mater., 2015, 27, 6360 LUXYOU 2015

(N,N-bis(1-phenylethyl)-16,22-bis(1,1':3',1''-terphenyl-5'-yl)-18,20-dioxa-19-phosphahexacyclo[$14,17!.0$2,7!.0$6,9!.0$8,13!]heptacosa-1(23),2,4,6,8,10,12,14,16,21,24,26-dodecaen-19-amine)-chloro-gold heptane solvate

No 3D coordinates and the structure is not discussed in the paper.

Zhiyong Wu, K.Isaac, P.Retailleau, J.-F.Betzer, A.Voituriez, A.Marinetti, Chem.-Eur.J., 2016, 22, 3278 NAHBEG 2016

4-(But-3-en-1-ylamino)-3-nitrobenzoic acid

Planar centrosymmetric dimers with a non-planar tail that stack in an offset fashion.

S. N. Narendra Babu, A. S. Abdul Rahim, H. Osman, S. R. Jebas, H. -K. Fun, Acta Crystallogr., Sect. E: Struct. Rep. Online, 2009, 65, o1560 POWLOD 2009


PLATON suggests an alternative space group, Pn21a with Z' = 6 (see Brock et al., Acta Cryst B., 2005, B61, 218)

S. Wingerter, M. Pfeiffer, F. Baier, T. Stey, D. Stalke, Z. Anorg. Allg. Chem., 2000, 626, 1121 QAJDAG 2000

6'-Methoxy-10-methyl-10,11-dihydrocinchonan-9-ol benzene solvate monohydrate

Complex solvate. Molecule has flat and bulky regions. Not discussed in the paper.

H.T.Dao, Chao Li, Q.Michaudel, B.D.Maxwell, P.S.Baran, J.Am.Chem.Soc., 2015, 137, 8046 RUKTOI 2015


Cyclic tetramers of a bulky secondary alcohol, consistent with the work of Brock and Duncan, Chem. Mater., 1994, 6, 1307.

M.P.Rahelivao, M.Gruner, T.Lubken, D.Islamov, O.Kataeva, H.Andriamanantoanina, I.Bauer, H.-J.Knolker, Org.Biomol.Chem., 2016, 14, 989 RUYZES 2016

2,3-diphenylacrylic acid propan-2-ol solvate

Solvate based on bulky carboxylic acid dimers. Not discussed in the publication.

Xueqiang Wang, M.Nakajima, R.Martin, J.Am.Chem.Soc., 2015, 137, 8924 SUPWUX 2015

Trimesic acid hydrate

Trimesic acid acts as host and guest. The length of a pair of trimesic acid guests corresponds to five layers of the trimesic acid hydrate host hence the structure can be formulated as two repeats of {(C9H6O6).H2O}5.C9H6O6.}

F. H. Herbstein, R. E. Marsh, Acta Crystallogr., Sect. B: Struct. Crystallogr. Cryst. Chem., 1977, 33, 2358 TRIMES10 1977

ammonium 5,5-dimethoxy-1,3,2-dioxaphosphinan-2-olate 2-oxide

Four polymorphs with Z' = 12, 6, 6 and 1. Chair - skew ring flipping, which takes place during single crystal to single crystal phase transitions, results in various populations of skew and chair conformers in different phases.

K.A.Slepokura, Acta Crystallogr.,Sect.B:Struct.Sci.,Cryst.Eng. and Mat., 2016, 72, 117 VIVSAV02 2016


δ polymorph For other polymorphs see ZZZVXQ03, ZZZVXQ05 and ZZZVXQ06

D. A. Parrish, J. R. Deschamps, R. D. Gilardi, R. J. Butcher, Cryst. Growth Des., 2008, 8, 57 ZZZVXQ02 2008


γ polymorph. For other polymorphs see ZZZVXQ02, ZZZVXQ03 and ZZZVXQ06

D. A. Parrish, J. R. Deschamps, R. D. Gilardi, R. J. Butcher, Cryst. Growth Des., 2008, 8, 57 ZZZVXQ05 2008

1,3,5-tris(4-Carboxyphenyl)benzene unknown solvate

Similar stacking arrangement to OGUROZ

C.A.Zentner, H.W.H.Lai, J.T.Greenfield, R.A.Wiscons, M.Zeller, C.F.Campana, O.Talu, S.A.FitzGerald, J.L.C.Rowsell, Chem.Commun., 2015, 51, 11642 OGUROZ01 2015

pentadecakis(tris(mu2-4-Methylpyrazolato-N,N')-tri-gold(I)) dichloromethane hexane methanol solvate dihydrate

The structure has a total of some 45 crystallographically unique gold(I) centres arranged into planar trimmers with significant Au...Au interactions, with each pair of gold(I) center bridged by a 4-methylpyrazolato anion. There are 15 crystallographically unique trimers with their packing dictated by further interplanar Au...Au interactions and the intercalation of the methyl substitutents within the concave groove of adjacent trimers to give offset stacks arranged not quite orthogonally. Based on reasonable aurophilic interactions Five gold trimers form independent units, while two exist as dimers of trimmers. An additional eight trimers, (with symmetry equivalents) constitute a 16-membered aggregate of trimers. In this way fairly close packing of the structure is achieved, with small lattice voids being occupied by a number of solvent molecules, namely a molecule of hexane, dichloromethane, methanol and two water molecules for every fifteen timeric complexes. The hexane is disordered. This unusual stoichiometry leads to a formal Z′ value of just 1, however a Z′ = 15 assignment has considerable justification and is arguably more useful.

G. Yang and R. G. Raptis, Inorg. Chem., 2003, 42, 261 MUTLAO 2003

Sodium t-butoxide

Later reinterpreted as Z' = 5 (NABUOX10) and Z' = 0.33 (NABUOX11)

T. Greiser, E. Weiss, Chem. Ber., 1977, 110, 3388 NABUOX 1977


Layer structure. Lower Z' polymorph known (BIPCOS, Z' = 4).For recent redetermination in P-1, Z' = 8 see BIPCOS02

S. Bruckner, Acta Crystallogr., Sect. B: Struct. Crystallogr. Cryst. Chem., 1982, 38, 2405 BIPCOS01 1982


Other Z' = 16 (CHOEST21) and Z' = 8 (CHOEST02, CHOEST10, CHOEST20) polymorphs also known

L. -Y. Hsu, C. E. Nordman, ACA, Ser. 2, 1981, 9, 35a CHOEST01 1981



Leh-Yeh Hsu, J. W. Kampf, C. E. Nordman, Acta Crystallogr. ,Sect. B:Struct. Sci., 2002, 58, 260 CHOEST21 2002

Cholesterol monohydrate

Early reported structure of cholesterol monohydrate. See CHOLES20 for Z' = 8 form and discussion of pseudosymmetry (B. M. Craven, Acta Crystallogr., Sect. B, 1979, 35, 1123) . A Z' = 4 form (CHOLES05) was also reported in 1963 (H. Bogren, K. Larsson, Biochim. Biophys Acta 1963, 75, 65-69) suggesting that significant twinning may invalidate this Z' = 16 form.

J. D. Bernal, Philos.Trans. R. Soc. London, Ser. A , 1940, 239, 135 CHOLES03 1940

beta-Est-2C hydrate

Protein-like β3 -peptide bundles possessing unique quaternary structures and catalytic activity. Active site triad composed of residues from at least two strands of the octameric bundle structure.

P.S.P.Wang, J.B.Nguyen, A.Schepartz, J.Am.Chem.Soc., 2014, 136, 6810 JIZFAB 2014

Sodium 1,2-benzisothiazol-3(2H)-onate 1,1-dioxide hydrate

Structure consists of "regular" and "irregular" regions held together by hydrogen bonds and Na···O interactions. The asymmetric unit contains 16 saccarinates (15 ordered and one disordered over two sites), 16 sodium ions (13 ordered and 3 disordered over two sites each) and 30 water molecules. 26 water molecules are ordered and all but one hydrogen atoms of these ordered water molecules were found from the Fourier map. The remaining four water molecules are disordered over two sites each. While the water oxygen atoms could be assigned with ease, only 1/4 of the hydrogen atoms could be found from the Fourier map.Also reported at same time by: P. Naumov, G. Jovanovski, O. Grupce, B. Kaitner, A. D. Rae, and S. W. Ng, Angew. Chem., Int. Ed., 2005, 44, 1251

R. Banerjee, P. M. Bhatt, M. T. Kirchner, G. R. Desiraju, Angew. Chem., Int. Ed., 2005, 44, 2515 LANBOS 2005

(15-Crown-5) triaqua-dichloro-dioxo-uranium

Cocrystal with Z'' = 32 comprising hydrogen-bonded chains on uranyl aqua complexes and [15]crown-5. The directionality of the multiple hydrogen bonding interactions is apparently incompatible with a more symmetrical structure and the asymmetric unit comprises four separate hydrogen bonded chains, each with four independent repeat units.

H. Hassaballa, J. W. Steed, P. C. Junk, Chem. Commun., 1998, 577 NIKZUC 1998

15-Crown-5 triaqua-dichloro-dioxo-uranium

See NIKZUC for preliminary communication of this structure.

H. Hassaballa, J. W. Steed, P. C. Junk, M. R. J. Elsegood, Inorg. Chem., 1998, 37, 4666 NIKZUC01 1998


No 3D coordinates reported. Cell length a is 102Å, structure is reported as Monoclinic ε polymorph therefore possibly there is an incorrect cell reported/determined?

N. I. Golovina, A. V. Raevsky, N. V. Chukanov, B. L. Korsunsky, L. O. Atovmyan, S. M. Aldoshin, Ross. Khim. Zhurnal(Russ. )(Russ. Chem. J. ), 2004, 48, 41-1 PUBMUU21 2004


No 3D coordinates

Shang-Shing P. Chou, Shih-Hsien Liu, J. Organomet. Chem., 1998, 555, 227 PUTKOE 1998


The 16 independent molecules all differ in minor conformational respects. The compound also forms a solvate with acetonitrile with Z′ = 2. The existence of high Z′ forms and low Z′ solvates/cocrystals is a recurring theme and the two extremes represent alternative solutions to the molecular packing problem. There are a number of conformations of similar energy and the quasiracemic nature of the material may also be a contributing factors (however high Z′ structures tend to be formed by more rigid molecules).

B. Braun, I. Kalf, U. Englert, Chem. Commun., 2011, 47, 3846 UNADOD 2011

4-(2,2,4-trimethyl-3,4-dihydro-2H-1-benzothiopyran-4-yl)phenol isopropanol solvate

Molecule with flat and bulky sections. Isostructural with Se analogue VANJAY.

C.S.Frampton, K.K.Ketuly, H.B.M.Ali, A.H.S.Azizan, J.H.Gall, D.D.MacNicol, CrystEngComm, 2017, 19, 2653 VANFUO 2017

4-(2,2,4-trimethyl-3,4-dihydro-2H-1-benzoselenopyran-4-yl)phenol isopropanol solvate

Molecule with flat and bulky sections. Isostructural with sulfur analogue VANFUO.

C.S.Frampton, K.K.Ketuly, H.B.M.Ali, A.H.S.Azizan, J.H.Gall, D.D.MacNicol, CrystEngComm, 2017, 19, 2653 VANJAY 2017


Each molecule in asymmetric unit has a unique conformation or orientation.

K. L. Fujdala, A. G. Oliver, F. J. Hollander, T. D. Tilley, Inorg. Chem., 2003, 42, 1140 HUVLAL 2003


ε polymorph. For other polymorphs see ZZZVXQ02, ZZZVXQ03 and ZZZVXQ05. All forms have Z′ values of three or more. All of the structures have a common “triad” motif, consisting of C-H...O hydrogen bonds and N-O...Br dipole-induced interactions. The differences between the polymorphs comes down to the orientation of sheet-to-sheet alignments. All five polymorphs were isolated concomitantly from the same vial provided by the Naval Surface Warfare Center and subsequent attempts to repeat the crystallization have only resulted in the Z′=3 alpha-form, suggesting perhaps a role of impurities in influencing the polymorphic outcome.

D. A. Parrish, J. R. Deschamps, R. D. Gilardi, R. J. Butcher, Cryst. Growth Des., 2008, 8, 57 ZZZVXQ06 2008


No 3D coordinates. Polymer. The Z' value relates to covalent monomers within a repeat of the covalent polymer strand.

P. Corradini, E. Martuscelli, G. Montagnoli, V. Petraccone, Eur. Polym. J., 1970, 6, 1201 HUGDOC 1970


Resolved chiral substance in P1. The sulfonamide groups are linked together by an 8-membered hydrogen bonded ring twisted slightly out of planarity by steric demands and by the formation of a bifurcated donor interaction to an additional molecule. There are also CH···pi interactions and some disorder of the vinyl group. Very minor conformational variations suggest that the optimization of hydrogen bonding and close packing considerations is a starting place to explain the very high Z′ value.

F. Kleinbeck, F. D. Toste, J. Am. Chem. Soc., 2009, 131, 9178 VUJBAE 2009


Likely to be significant errors in the original paper regarding unit cell length and crystal class. Z' is likely to be either 1 or 1.5.

T. Hashimoto, M. Toyota, H. Koyama, A. Kikkawa, M. Yoshida, M. Tanaka, S. Takaoka, Y. Asakawa, Tetrahedron Lett., 1998, 39, 579 BEWZEI 1998

22-cyclo-octa-1,5-diene)-((S)-2-(1,1-diphenylethyl)-4-(2-(bis(2-methylphenyl)phosphino)ethyl)oxazoline-N,P)-iridium tetrakis(3,5-bis(trifluoromethyl)phenyl)borate

The structure is not discussed in the original publication but the authors report that the unit cell can be reduced to a higher symmetry Z′ = 1 sub-cell. This description does not account for some relatively weak interlayer reflections that give rise to the much higher Z′ supercell and it is likely that the structure is an incommensurately modulated version of the high symmetry structure.

D.-R. Hou, J. Reibenspies, T. J. Colacot, K. Burgess, Chem. Eur. J., 2001, 7, 5391 IDOSID 2001

Trimethyl-tin hydroxide

83 helical superstructure arising from short Sn···O interactions. No 3D coordinates but the published paper contains a careful study on possible sub-cells. A reinvestigation has been published: Cryst. Growth Des. 2011, 11, 820.

N. Kasai, K. Yasuda, R. Okawara, J. Organomet. Chem., 1965, 3, 172 TMESNH 1965

1,3,5-tris(4-Carboxyphenyl)benzene unknown solvate

Z' world record holder. See also Z' = 14 polymorph OGUROZ01. 8-fold polycatenated assembly of (6,3) hexagonal nets formed through hydrogen bonds and π-stacking. The stack length seems to depend on the included solvent.

C.A.Zentner, H.W.H.Lai, J.T.Greenfield, R.A.Wiscons, M.Zeller, C.F.Campana, O.Talu, S.A.FitzGerald, J.L.C.Rowsell, Chem.Commun., 2015, 51, 11642 OGUROZ 2015