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N(CH3)4 ╖ ZnH3(PO4)2 A Large-Pore Zincophosphate Built Up from a 12-Ring Architecture with a Remarkably Low Tetrahedral-Framework-Atom Density.

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N(CH,), .ZnH,(PO,), : A Large-Pore
Zincophosphate Built Up from a 12-Ring
Architecture with a Remarkably Low
Tetrahedral-Framework-Atom Density**
William T. A. Harrison* and Lakshitha Hannooman
Work on the synthesis and characterization of new microporous materials continues apace, revealing an ever-increasing
variety of framework compositions and topologies.(’. Herein
we report the synthesis and X-ray single-crystal structure of
,a novel large-pore zincophosphate built
up from a an unprecedented 12-ring topology. A synthetic route
to small crystals of N(CH,);ZnH,(PO,),
and physical data on
the same phase were reported earlier.r31
N(CH,), .ZnH,(PO,), consists of a three-dimensional anionic Zn/P/O/H network that encloses a two-dimensional network of 12-ring channels, which are occupied by tetramethylammonium (TMA) ions. The zinc atom (site symmetry . .2)
forms Zn-0-P bonds to four distinct phosphorus atom neighbors (d,,(Zn-0) = 1.932(4) A) (Figure 1, Tables 1 and 2). The
phosphorus atoms each bond to four distinct oxygen atom species; two bonds are formed to Zn through 0(1) and 0(2), and
two terminal P - 0 links are formed to O(3) and O(4) (d,,(P0) = 1.533 (4) A). The extraframework TMA ion (N site symmetry . .2) shows extensive disorder of its carbon atoms, although the nitrogen species is well ordered. A TLS (Translation,
Libration, Screw libration) thermal motion analysis[41indicated
that the displacements of the carbon atoms of the TMA species
were essentially exclusively librational, and corrected N-C
bond lengths of z 1.5 8, resulted.
Figure 1. Crystal structure of the 12-ring building unit in N(CH,);ZnH,(PO,),
showing the atom labeling scheme (50% thermal ellipsoids). Possible intraframework hydrogen-bonding linkages are indicated by dotted lines.
Table 1. Positional and thermal parameters for the atoms in
-0.1 294 (1)
-0.0858 (4)
-0.1492 ( 5 )
0.026( 2 )
0.0334 (2)
0.1427 (8)
- 0.1226 (6)
0 398(2)
-0.0007 (2)
- 0.1 567 (2)
- 0.1476( 5 )
- 0.1429(7)
-0.098 ( I )
- 0.196(2)
Figure 2. View approximately down [OlO] of the zincophosphate framework of
N(CH,),.ZnH,(PO,), showing the 12-ring topology. The T M A ions are omitted
for clarity.
The connectivity of the ZnO, and (HJPO, units in
results in a strict alternation of zinc- and
phosphorus-centered tetrahedra. No Zn-0-Zn or P - 0 - P
bonds are present, despite the Zn:P framework ratio of 1:2. The
smallest identifiable loop configuration formed by these fused
tetrahedral units is a 12-ring, that is 12 tetrahedral centers, or 24
atoms in total (6 Zn, 6 P, and 12 0; Figures 1 and 2). Each
12-ring is associated with a TMA guest ion. There are no Hbonding interactions between the TMA and the framework,
since the positive charge on the N atom is shielded by its four
[*] Dr. W T. A. Harrison, L. Hannooman
Department of Chemistry. University of Western AUStralkd
Nedlands, WA 6907 (AUStrdh)
Fax: Int. code +(9)380-1005
This work was supported by the Australian Research Council (Grant No.
8 VCH Verlagsgesel1,~chaftmbH, D-694Sl
Weinheim. 1997
methyl substituents. The framework 12-ring is constricted at
one end, resulting in a pear-shaped cavity (Figure 1). Its maximum dimensions, measured from 0 atom to 0 atom, are approximately 7.1 x 8.8 A. Charge-balancing considerations require the presence of three framework protons. These could not
be located in the crystal structure determination and they may
be distributed over both the terminal P - 0 oxygen atoms [0(3)
and 0(4)] with a statistical occupancy of 7 5 % : This situation
could also be represented by the “ordered” formula of
N(CH,),. Zn(HPO,)(H,PO,). Two intraframework hydrogen
bonds are possible in the pear-shaped 12-ring; the short nonbonded 0-0 contacts are 2.41 and 2.61 8,. Overall, a twodimensional channel system of squashed 12-ring channels propagating in the [I011 and [lor] directions, and more regular 12ring channels propagating in the [I101 and I1701 directions results (Figures 3 and 4).
The framework density (FD: number of tetrahedral atoms
per 1000
of N(CH,),.ZnH,(PO,),
is 10.1. This, as far as
we are aware, is the lowest FD value observed so far for any
OS70-0833/97/3606-0640$ /?.SO+ SOJO
A n g e ~ .Chcm. In?. Ed E m g l 1997, 36. No. 6
Table 2 Selected bond lengths [A] and angles [“I for N(CH,), ZnH,(PO,),
Zn (l)--O ( l ) xZ
P(1)- O(1)
P(1) O(3)
N(1) ~ C ( 1 ) x Z
O ( l ) - Z n ( l )- O ( l )
O(1) ~ Z n ( 1 -) O ( 2 )
0 (1 ) P (1 ) 0 (2)
0 (2) P(1) O (3 )
O(2)- P(1) -O(4)
Z n ( l ) - O ( l ) P(1)
1.31 (2)(d]
Zn(l)-O(2) x 2
p (1) - 0 (2)
P (1)- 0 (4)
N (1) - C (2) x 2
0(1)-Z n(l)-0(2)
0 (2) --Zn( I )-0 (2)
O(l)-P (l)-0(3)
0 (3)- P (1) 0 (4)
Zn (1 )-O(2)- P(1)
1 935(7)
1.36 (2)[a]
106.9( 5 )
[a] Uncorrected for libration, see text
teractions between the guest cation and the anionic zincophosphate framework. N(CH,);ZnH,(PO,),
is distinct from these
materials in its lack of any framework-template hydrogen
bonds, although framework-framework hydrogen bonds are
presumably present, as noted above. The TMA ion has found
wide applicability as a template in aluminosilicate‘81and alumin~phosphate[’~
syntheses, although the resulting frameworks
are quite different to the phase described here.
Exper imenfal Section
Synthesis: N(CH,),-ZnH,(PO,), was prepared at ambient conditions from the
reaction of 85% phosphoric acid (4.8 g), 25 % tetramethy~ammoniumhydroxide
solution (1 1.66 g), and 50 % rubidium hydroxide solution (2.46 g). This mixture was
shaken together in a plastic bottle until homogeneous. Then zinc nitrate (5.32 g) was
added, which resulted in the formation of a white gel. The bottle was shaken again
and a white precipitate formed. After the initial white powder was filtered off,
well-faceted plates of a rubidium zinc phosphate phase crystallized over a few
minutes. A second filtration of these crystals resulted in a clear solution. After the
mixture had been left to stand for two days, a mixture of numerous rods and a few
large translucent lumps of N(CH,);ZnH,(PO,),
formed. A crystal of N(CH,);
ZnH,(PO,), suitable for structure determination by single-crystal X-ray methods
was cut from a larger lump. We have not yet managed to obtain good quality single
by a more direct synthetic route.
crystals of N(CH,);ZnH,(PO,),
Sfrurture determination. A weakly diffracting crystal of N(CH J b . ZnH,(PO,),
(dimensions -0.3 x 0.3 x 0.4 mm) was selected for data collection on a
Siemens P4 automated diffractometer (graphite-monochromated Mo, radiation,
7. = 0.71073 A, T = 298 K): cell parameters from 36 centered reflections
(1 1 <20 < 3 0 ) , 1322 reflections scanned: 2 ” <2O<60“, - 1 I
h 5 22, - 1 $ k < 13,
- 1 I / < 2 1 . 812 reflections considered observed [1>3u(1)] after data reduction
(Lorentz and polarization corrections; absorption corrected for oil the basis of jl
scans; min./max. equivalent transmission factors = 0.465, 0.555) and merging
(R,,, = 0.030) Space group determined unambiguously from systematic absences,
structure solved by direct methods usmg SHELXS86 [lo], refined by full-matrix
least squares using CRYSTALS Ill], and illustrated by using CAMERON [I21
Anisotropic thermal factors for all atoms and a Larson-type secondary extinction
correction refined. No protons could he located from final difference maps (min./
max. A p = -1.1, + 0 . 9 e k 3 ) . Fins[ residuals: R(F) = 0.043. R,(f) = 0.049
[n,= l/&F)]. Crystal data. N(CH,),-ZnH,(PO,),, M, = 332 49. orthorhombic,
space group Fdd2 (no. 43). a = 15 972(3), h = 9.863(2). c = 15.156(3)
V = 2388(1) A’, 2 = 8, prrlcd= 1.85 gcrn-, Further details of the crystal structure
investigation may be obtained from the Fachinformationszentrum Karlsruhe, D76344 Eggenstein-Leopoldshafen (Germany) on quoting the depository number
Received: September 4, 1996 [Z9526IE]
German version: Angew. Chem. 1997. 109. 663- 665
Figure 3 View approximately down [loll of the squashed 12-ring channels in
For clarity, the Zn/P/O framework is represented in“skeletal” form. showing Zn to P connectivity only.
Keywords: microporosity
tures zeolite analogues
Figure 4. View approximately down [I 101 of the more regular 12-ring channels in
N(CH,),.ZnH,(PO,), Forclarity, the Zn/P:O framework is represented in “skeletal” form. showing Zn io P connectivity only.
open-framework material built up from tetrahedral building
units, although in this case the framework is “interrupted”; that
is, not all the tetrahedrally coordinated atoms make four bonding connections. The interrupted tetrahedral gallofluorophosphate framework of cloverite[61has a FD value of 11.1,
whereas Cs,[V,O,(PO,),]~xH,O, which contains a remarkable,
diamondlike three-dimensional array of 32-ring spheroidal cavities”’ has a FD value of about 9.3 (square pyramidally surrounded V atoms, tetrahedrally surrounded P atoms).
A number of other zincophosphates templated by organic
cations have been reported previously.[3,71 These are mostly
characterized by structurally important hydrogen bonding in
Angex,. Chem. In!. Ed. Engl. 1991.36. No. 6
molecular sieves
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[ l l ] D. J. Watkin, J. R. Carruthers, P. W. Betteridge, CRYSTALS user guide,
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[12] L. J. Pearce, C. K. Prout, D. J. Watkin. CAMERON user guide, Chemical
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