A view on (001) shows the corrugation of the [Se₂MoO₈]_n^2n- chains.

(The unit cell is outlined.)

The cyclic, polar polyoxometalate anion (SeS₃Mo₆O₃₁)^8-

(a) and (b): Different views of the [SeS₃Mo₆O₃₃]^8- anion show the connection of
octahedra and tetrahedra.

(c): A perspective view of a ball and stick model of [SeS₃Mo₆O₃₃]^8- with the
atomic labelling scheme. Se-O(1) 170.0(3), Se-O(2) 170.2(4), Se-O(3) 169.5(3)pm,
O-Se-O angles 98.10(15)-98.73(17)°; range of Mo-O bonds: short 169.0(4)-171.4(4),
medium 189.0(3)-193.6(4), long 225.5(4)-232.3(4)pm.
Mo-Mo short: 337.0(1)-338.5(1), long: 359.1(1)-363.3(1)pm. S-O:S(1)
143.0(5)-149.7(4), S(2) 145.0(5)-149.2(4), S(3) 141.5(7)-149.9(5)pm.

(Li₁₀(H₂O)₂₀(Se₄Mo₆O₃₀)₂)^6-

Two (Se₄Mo₆O₃₀)^8- anions are linked by Li⁺ cations to form the anionic cluster
of (Li₁₀(H₂O)₂₀(Se₄Mo₆O₃₀)₂)^6- composition.

The tetrameric (Se₄Mo₂₄O₁₀₈S₄C₁₆H₂₄)^24- anion with

    thio-diacetic acid moieties serving as linkers.

The chiral, chain-like polyanion (SeMo₆O₃₁C₈H₈)_n^6n- with

diglycolic acid moieties as linking blocks.

The (Se₂Mo₁₂O₄₂(C₁₂H₁₂O₁₂))^10- anion with succinic
      acid residues as linkers.

C. Robl and M. Frost:

The cyclic tellurium - rich (Te₆Mo₁₂O₆₀)^12- anion

The entire [Te₆Mo₁₂O₆₀]^12-anion viewed from the [001] direction. (The
coordination octahedra around Te are shaded.)

Adjacent pairs of MoO₆ octahedra do not share oxygen atoms with one
another, but only with the TeO ₆ octahedra to which they are attached. Hence,
the anion lacks a continuous -O-Mo-O-Mo-O-pathway and may be
formulated alternatively as [Te₆O₆(Mo₂O₉)₆]^12- .

C. Robl and V. Göbner:

The [Be₃(PO₄)₃(OH)]_n ^4n- anion

(a) A model of the [Be₃(PO₄)₃(OH)]_n ^4n- anion ( Be atoms). Bond lengths
(pm): Be-O(1) 160.0(3),Be-O(2)160.9(3), Be-O(3)162.8(3), Be-OH 174.5(2),
P-O(1) 153.4(2), P-O(2) 154.6(1), P-O(3) 154.4(1), P-O(4) 152.6(1);

(b) The [Be₃(PO₄)₃(OH)] _n^4n- anion composed of corner-sharing tetrahedra

(Be centered tetrahedra are hatched). All O-H vectors posses the same
direction and run parallel to [001].

LiBePO₄•H₂O

A polar channel-like void extending parallel to [001] and accommodating
water molecules co-ordinated to Li⁺ is the characteristic structural feature
of LiBePO ₄ • H₂O. This framework is composed of tetrahedral building
blocks linked by common corners to yield eight-, six- and four-membered
rings, respectively.

Interatomic distances (pm): P-O(1) 152.0(7), P-O(2) 152.1(7) P-O(3) 156.3(8),
P-O(4) 152.9(6), Be-O(1) 161(1), Be-O(2) 165(1), Be-O(3) 164(2), Be-O(4) 160(3),
Li-O(w) 185(2),Li-O(2) 196(2), Li-O(3) 196(2), Li-O(4) 197(2);

selected angles (°): P-O(1)-Be 140.43(64), P-O(2)-Be 141.60(94), P-O(2)-Li 114.83(58), Be-O(2)-Li 103.32(98), P-O(3)-Be 130.75(86), P-O(3)-Li 117.96(74),

Be-O(3)-Li 109.40(98), P-O(4)-Be 127.81(57), P-O(4)-Li 123.67(75),
Be-O(4)-Li 103.72(84)

Coordination Polymers with Anions of Benzene Carboxylic Acids

C. Robl:

Zeolite - like channels accommodating clusters of water

molecules (omitted for sake of clarity) in the coordination

polymer Na₂Zn(C₆H₂(COO)₄)• 9H₂O

The zeolite-like framework viewed from [100]. ( Water molecules have been
omitted; coordinative bonds are shown as thin lines.)

Cd_3-xNa_2x(C₆(COO) ₆ ) • 9,5 H₂O

A cadmium mellitate with zeolite - like structural features.

The layer structure of
       Cu(C₄H₄N₂)_0.5[C₆H₂(COO)₄]_0.5•3H₂O

a)	b)
The chains of copper cations and pyromellitate tetraanions are linked by pyrazine molecules to a layer. a) view along [010], water molecules have been omitted b) view along [100]

The zeolite-like framework of

Cu_1.5(H₃N-(CH₂)₆-NH₃)_0.5[C₆H₂(COO)₄]• 5H₂O

a)		b)
a) The zeolite-like framework viewed from [100].      1,6-Hexanediammonium-cations occupy these channels together with water        molecules. b) Space filling model of the zeolite-like framework, water molecules and      ammonium-cations are not drawn (view along [100]).

Co(H₃N-C₆H₁₀-NH₃ )[C ₆ H₂(COO)₄]• 2H₂O
    a three-dimensional, open framework

a)
b)		c)
The Co 2+ cations and pyromellitate tetraanions build up a zeolite-like framework with large channels in [001], [110] and [1-1 0]direction. The channels accommodate water molecules and trans- 1,4-cyclohexanediammonium-cations. a) View into a channel along [001]. b,c) Space filling model of the zeolite-like framework (water molecules and               ammonium-cations are not shown). b)  viewed from [001] c)  viewed from [110]

C.Robl and M. Arnold:

Cu₂[O₃P(CH₂)₂PO ₃ ] •3H₂O

The highly symmetric open framework of Cu₂[O₃P-CH₂-CH ₂ -PO₃]• 3H₂O.
(Water molecules have been omitted.)

Cu_1,5[OOC(CH₂)₂PO₃] • 4H₂O

The open framework coordination polymer with channels extending parallel to
[100] in Cu_1,5[OOC-CH ₂-CH₂-PO ₃ ] • 4H₂O.

C.Robl and W.F.Kuhs:

(Al₂[C₆(COO)₆]• 16H₂O)

A section of the hydrogen bonding system in the mineral mellite, studied by
single crystal neutron diffraction at 15 K.

C.Robl, S. Hentschel and G. J. McIntyre:

Be[C₂(COO)₂]• 4H₂O

Hydrogen bonding in Be[C₂(COO)₂]•4H₂O as determined by neutron
diffraction at 15 K: Layers made up by hydrogen bonded [C₂(COO)₂]^2-anions
extending parallel to (010) are stacked in . . . ABAB . . . sequence and
interlinked by coordinative bonds between Be²⁺and H₂O (open bonds sticks).

A concise compilation focusing on selected polyoxometalates and coordination polymers studied by us is given in:

C.Robl: "Polyoxometalates and Coordination Polymers" in: Luigi Fabbrizzi
and Antonio Poggi (eds.),

Chemistry at the Beginning of the Third Millennium, Springer Verlag,

Berlin 2000, p.279ff.