Journal of

MOLECULAR STRUCTURE

Journal of Molecular Structure 474 (1999) 143- IS5

Crystal and molecular structure of potassium, ammonium and dicyclohexylammonium salts of (2-oxopropyl) phosphonic acid in

monoionized state *

Jaroslaw Mazurek, Tadeusz Lis*

Received 1 December 1997; received in revised form 3 February 1998; accepted 3 February 1998

Abstract

The crystal and molecular structures of potassium (I), ammonium (II) and dicyclohexylammonium (III) (2-oxopropyl) phosphonates were determined by X-ray methods. For all three compounds the monoionized anion has a similar conformation, with the phosphonate group projected out of the ketone backbone. The crystals of I and II contain two symmetry-independent anions and cations in the asymmetric unit, the anions are arranged in tetramers by strong hydrogen bonds. In the crystals of III the anions are arranged in hydrogen-bonded dimers. The anions differ mostly in the orientation of the hydroxyl group, being + gauche for Ia, IIb and III, nearly antiperiplanar for Ib, and - gauche for IIa, with regard to the C(C0) atom. In all cases the hydrogen bonds between phosphonate groups are strong. The hydrogen bonds between anions and ammonium and dicyclo- hexylammonium cations display normal strength. In all crystals the carbony atom is an acceptor of hydrogen from the methyl or methylene group. The K-cations in I are hexacoordinated and four of them are arranged in a cubane-like structure connected through four phosphonate 0 atoms. 0 I998 Elsevier Science B.V. All rights reserved.

Keywords: (2-oxopropyl) phosphonate monoanions; Intermolecular hydrogen bonds; Weak C-H. .O intermolecular contacts

1. Introduction

Phosphonate chemistry is of interest to biology because the carbon-phosphorus bond in phospho- nates, unlike in phosphate esters, is not susceptible to hydrolytic actions of phosphatases, imparting stabi- lity and longer duration of action under physiological conditions [ 11. Phosphonate analogues of biologically important phosphates have been found in carbohy- drates, amino acids, lipids, nucleotides, etc. [2,3]. Among the most important phosphates in living

* This paper is dedicated to Professor Zofia Kosturkiewicz on the occasion of her 70th birthday.

* Corresponding author. Fax: + 48-71-222348.

systems are the glycolysis intermediates, so that the phosphonates, which are isosteric or non-isosteric analogues, could be used as models in studies of the mechanism of energetic processes in biology [l-3]. The phosphonate analogues of dihydroxyacetone phosphate (DHAP) have been known in the litera- ture since the 1970s. One of the best known from those is 4-hydroxy-3-oxobutylphosphonic acid [4- 6], which is isosteric with DHAP. There are also numerous non-isosteric analogues of DHAP, for instance the aliphatic oxophosphonates, which have been used for the study of some enzyme-catalysed reactions [7,8]. Structural information about oxopho- sphonic acids and their salts could be helpful in understanding the interactions of phosphates with

0022-2860/98/$ - see front matter 0 1998 Elsevier Science B.V. All rights reserved. PII: SOO22-2860(98)00568-7

144 .I. Mazurek, T. Lis / Jountul of Moleculm- Structure 474 (1999) 143-155

9- (Scheme 1): potassium, ammonium and dicyclohexy-

tip-C-Cl&OH II II 0 0

1ammonium;which may be treated as non-isoste& analogues of DHAP.

Scheme I. 2. Experimental

the above-mentioned enzymes. So far only the structures of sodium (1-oxoethyl) phosphonate acetic acid solvate (by Jones and Kennard [9]) and dicyclohexylammonium (1-oxopropyl) phosphonate and (I-oxobutyl) phosphonate (by us [lo]) have been determined. This article presents three salts of (2-oxopropyl) phosphonic acid in monoionized state

Table 1 The crystal data and structure refinement of I, II and III

Crystals of III were obtained through the recrystal- lization from 2-propanol of compound given by Prof. P. Kafarski (Technical University of Wroclaw). Compounds I and II were obtained by modification of the method described by Zygmunt et al. [1 I], as follows: 2 g of diethyl (2-oxopropyl) phosphonate

I II III

Empirical formula Formula weight T(K) Radiation Crystal system Space group Unit cell dimensions

a (A) b (A) c A a (“) P (“) Y (“) v (A3) Z D, [g/cm’]

/L [mm-‘1 Crystal size [mm] Crystal habit Crystal colour 0 range (“) Index ranges

Reflections collected Reflections independent Reflections observed [I > 2401 Goodness-of-fit R V ’ 20 (01

R (all data)

Weighting scheme”

K+C3HhOJP 176.15 120 (2)

MoK, Monoclinic C2lc

24.899 (6) 7.466 (3) 14.917 (6)

107.06 (3)

2651.0 (16) 16 1.765 0.983 0.6 x 0.4 x 0.3 Rhombohedral block Colourless 2 to 30 OGhS34 OskS IO - 20 5 1 S 20

3924 [R,,,,, = 0.0109] 3852 322 1

1.109 R = 0.0283 v/R2 = 0.0755 R = 0.0380, wR* = 0.0800 l/[a*(Fo) + (0.05P)’ + 1.3P]

NHJ+GHhOJP 155.09 302 (1) MoL Triclinic P1

8.053 (3) 8.112 (4) 11.919 (6) 67.84 (3) 74.63 (3) 87.62 (3) 693.8 (6) 4 1.485 0.346 0.5 x 0.4 x 0.2 Irregular Colourlehs 2 to 22,s OS/IS8

-8 Sk~8 - 12 G 1 S 12

1956 [R,,,,, = 0.03531 1799 1520

1.071 R = 0.0324 wR2 = 0.0837 R = 0.0418 wR’ = 0.0898 l/[a*(Fo) + (0.06P)’ + 0.2P]

C ,2H24N +CoHh04P 319.37 120 (2)

MoK, Monoclinic P2,ln

9.280 (6) 10.862 (9) 16.806 (10)

98.48 (6)

1676 (2) 4 1.266 0.179 0.3 x 0.3 x 0.1 Parallelepiped Colourless 2 to 25 OGhG9 - 12skSO - 19s 1 S20

2590 [R,,,,, = 0.02291 2397 1466

1.199 R = 0.0390 wR’ = 0.1056 R = 0.1012 wR’= 0.1244 I/[cr*(Fo) + (0.028P)’ + 3.2P]

a P = [max(Fo2) + 2Fc2]/3

Table 2

J. Mazurek, T. Lis / Journal of Molecular Structure 474 (1999) 143-155 145

Fractional atomic coordinates and equivalent anisotropic displacement parameters (A’)

I K (la) P (la) 0 (la) 0 (2a) 0 (3a) 0 (4a) C (la) C (2a) C (3a) K(lb) P (lb) 0 (lb) 0 (2b) 0 (3b) 0 (4b) C (lb) C (2b) C (3b) H (3a) H (lla) H (12a) H (3la) H (32a) H (33a) H (2b) H (I lb) H (12b) H (3lb) H (32b) H (33b) II

P (Ia) 0 (la) 0 (2a) 0 (3a) 0 (4a) C (la) C (2a) C (3a) P(1b) 0 (lb) 0 (2b) 0 (3b) 0 (4b) C (lb) C (2b) C (3b) N (1) N (2) H (la) H (11)

0.437394 (1 I) 0.078 16 (4) 0.4 18944 (13) 0.58352 (4) 0.44547 (4) 0.44280 (13) 0.45370 (4) 0.66286 (15) 0.39459 (5) 0.74228 (13) 0.33059 (4) 0.21962 (13) 0.35686 (5) 0.4890 (2) 0.32276 (5) 0.3800 (2) 0.27947 (7) 0.4749 (3) 0.442192 (11) 0.40609 (3) 0.420754 (13) - 0.09928 (4) 0.45023 (4) 0.03810 (13) 0.45605 (4) - 0.16043 (14) 0.39986 (4) - 0.26319 (12) 0.33064 (4) 0.26182 (14) 0.36145 (5) 0.0076 (2) 0.32523 (5) 0.1023 (2) 0.28369 (6) - 0.0077 (3) 0.3966 (14) 0.727 (4) 0.3701 (9) 0.410 (3) 0.3354 (9) 0.587 (3) 0.2509 ( 13) 0.502 (5) 0.2681 (12) 0.400 (4) 0.2955 (15) 0.571 (5) 0.4839 ( 12) - 0.222 (4) 0.3416 (9) - 0.080 (3) 0.3749 (11) 0.101 (3) 0.2504 (13) - 0.010 (4) 0.2767 (13) 0.063 (4) 0.2990 (13) - 0.112 (5)

0.71045 (7) 0.89 17 (3) 0.6415 (2) 0.5908 (2) 1.0121 (3) 0.7675 (4) 0.8679 (4) 0.7892 (5) 0.208 18 (8) 0.32 11 (3) 0.0580 (2) 0.3155 (3) 0.3802 (3) 0.1284 (4) 0.2709 (4) 0.2757 (5) 0.2916 (4) 0.6682 (4) 0.895 (4) 0.296 (4)

0.63625 (8) 0.6794 (3) 0.4506 (2) 0.7795 (3) 0.7705 (3) 0.6292 (4) 0.7870 (4) 0.9618 (5) 0.24367 (7) 0.0910 (2) 0.2206 (3) 0.4168 (3) 0.2767 (3) 0.2900 (5) 0.3689 (4) 0.5621 (5) 0.7763 (3) 0.0936 (5) 0.715 (4) 0.687 (4)

0.81499 (2) 0.84252 (2) 0.79812 (7) 0.93411 (7) 0.77312 (7) 0.78084 (7) 0.86630 (9) 0.78493 (9) 0.70827 (1 I) 0.61057 (2) 0.5693 1 (2) 0.63957 (6) 0.50282 (6) 0.60852 (6) 0.55070 (8) 0.48498 (8) 0.53491 (9) 0.56630 (1 1) 0.7216 (22) 0.9226 (14) 0.8806 (15) 0.7342 (21) 0.6534 (20) 0.6883 (24) 0.5287 (20) 0.4453 (15) 0.4471 (17) 0.5199 (20) 0.6154 (21) 0.5855 (22)

0.74067 (5) 0.7509 (2) 0.8302 (2) 0.7473 (2) 0.4206 (2) 0.5848(3) 0.4787 (3) 0.4451 (4) 0.9663 1 (5) 0.9767 (2) I .0777 (2) 0.9381 (2) 0.6770 (2) 0.8291 (3) 0.7097 (3) 0.6364 (3) 0.9365 (5) 0.7755 (3) 0.8 10 (3) 1.011 (3)

0.01263 (7) 0.01006 (8) 0.0130 (2) 0.0197 (2) 0.0180 (2) 0.0176 (2) 0.0125 (2) 0.0125 (2) 0.0232 (3) 0.01244 (7) 0.00897 (8) 0.0132 (2) 0.0147 (2) 0.0144 (2) 0.0207 (2) 0.0 127 (2) 0.0138 (2) 0.0202 (3) 0.057 (9) 0.017 (5) 0.019 (5) 0.057 (8) 0.042 (7) 0.066 (IO) 0.047 (7) 0.018 (5) 0.031 (6) 0.050 (8) 0.052 (8) 0.059 (9)

0.0263 (2) 0.0400 (5) 0.0359 (5) 0.0370 (5) 0.0584 (6) 0.0329 (6) 0.0369 (6) 0.0599 (9) 0.0258 (3) 0.0365 (5) 0.0383 (5) 0.0370 (5) 0.0620 (7) 0.0390 (7) 0.0398 (7) 0.0524 (8) 0.0318 (5) 0.0441 (7) 0.056 (9) 0.041 (8)

146

Table 2 (continued)

J. Mazurek, T. Lis / Journal of Molecular Structure 474 (1999) 143-155

H (12) H (13) H (14) H (21) H (22) H (23) H (24) H (21a) H (22a) H (31~s) H (32a) H(33a) H(3b) H(2lb) H (22b) H(31b) H (32b) H (33b) III P(1) 0 (I) 0 (2) 0 (3) 0 (4) c (1) c (2) c (3) N(l) c (11) c (12) c (13) c (14) c (15) C(16) c (21) c (22) c (23) c (24) c (25) C (26) H(1) H (2) H (3) H (11) H (12) H(31) H (32) H (33) H (II I) H(121) H (122) H(l31) H(132)

0.311 (4) 0.882 (5) 0.381 (5) 0.772 (5) 0.187 (4) 0.754 (4) 0.677 (5) 0.052 (5) 0.605 (6) 0.161 (6) 0.634 (7) 0.022 (7) 0.766 (5) 0.145 (5) 0.826 (4) 0.531 (4) 0.671 (5) 0.613 (4) 0.841 (6) 1.041 (6) 0.728 (8) 0.990 (8) 0.655 (7) 0.944 (7) 0.413 (5) 0.414 (4) 0.049 (4) 0.360(4) 0.086 (4) 0.183 (5) 0.371 (5) 0.599 (4) 0.173 (6) 0.595 (5) 0.282 (5) 0.629 (6)

0.16677 (12) 0.2891 (3) 0.1845 (3) 0.0236 (4) 0.2623 (4) 0.1380(5) 0.1552 (5) 0.0388 (6) 0.4204 (4) 0.4165 (5) 0.2654 (5) 0.2657 (5) 0.3246 (5) 0.4737 (5) 0.4700(5) 0.3690 (5) 0.3875 (5) 0.3283 (5) 0.3992 (5) 0.3901 (5) 0.4479 (5) 0.358 (6) 0.516 (5) - 0.034 (6) 0.198 (5) 0.048 (5) - 0.048 (6) 0.012 (5) 0.063 (5) 0.4846 0.2335 0.1957 0.3263 0.1651

0.39679 (99) 0.3712 (3) 0.5042 (3) 0.4106 (3) 0.0775 (3) 0.2604 (4) 0.1423 (4) 0.1068 (5) 0.6712 (3) 0.7358(4) 0.7823 (4) 0.8420(J) 0.7556(4) 0.7071 (4) 0.6460(4) 0.7391 (4) 0.6543 (4) 0.7165 (4) 0.8418(4) 0.9235 (4) 0.8604 (4) 0.589 (6) 0.654 (4) 0.429 (5) 0.261 (4) 0.271 (4) 0.091 (5) 0.172 (5) 0.034(5) 0.8076 0.8430 0.7127 0.9173 0.8667

0.941 (3) 0.871 (4) 0.926 (3) 0.854 (4) 0.770 (4) 0.743 (5) 0.726 (4) 0.589 (3) 0.579 (3) 0.370 (5) 0.516 (6) 0.442 (5) 0.912 (3) 0.833 (3) 0.835 (3) 0.561 (4) 0.615 (4) 0.685 (4)

- 0.03571 (6) - 0.0809 (2) 0.0218 (2) - 0.0973 (2) - 0.0004 (2) 0.0240 (3) - 0.0188 (3) ~ 0.0853 (3) 0.0336(2) - 0.0458 (2) - 0.0789 (3) - 0.1605 (3) - 0.2200 (3) - 0.1851 (3) - 0.1043 (2) 0.1017 (3) 0.1750(3) 0.2446 (3) 0.2649 (3) 0.1907 (3) 0.1209 (3) 0.027 (4) 0.052 (3) - 0.082 (3) 0.071 (3) 0.043 (3) - 0.061 (3) - 0.121 (3) - 0.117 (3) ~ 0.0384 - 0.0412 - 0.0841 - 0.1539 - 0.1826

0.052 (9) 0.065 (IO) 0.035 (8) 0.067 (IO) 0.071 (14) 0.122 (19) 0.062 (11) 0.043 (8) 0.045 (9) 0.105 (15) 0.169 (25) 0.142(19) 0.050(10) 0.036 (8) 0.062 (10) 0.064 (IO) 0.075 (II) 0.086(13)

0.0168 (3) 0.0196(7) 0.0220(7) 0.0226 (7) 0.0392 (9) 0.0205 (10) 0.0242 (10) 0.0311 (II) 0.0167 (8) 0.0186(9) 0.0190(9) 0.0263 (IO) 0.0285 (II) 0.0272 (11) 0.0189 (9) 0.0184 (9) 0.0203 (9) 0.0263 (10) 0.0250 (IO) 0.0247 (10) 0.0225 (10) 0.070(18) 0.018(11) 0.025 (18) 0.027 (12) 0.009 (10) 0.063 (18) 0.029(12) 0.034 (13) 0.013 (IO) 0.015 (IO) 0.029 (12) 0.016 (10) 0.018 (10)

J. Mazurek, T. Lis / Jooumal of Molecular Structure 474 (1999) 143-155 147

Table 2 (continued)

X Y Z Ik’\“JUkq,

H (141) 0.2565 0.6858 - 0.2328 0.030 ( 12) H (142) 0.3313 0.8005 - 0.2706 0.022 (10) H (151) 0.5444 0.7759 - 0.1786 0.034 (I 3) H (152) 0.5065 0.6468 - 0.2228 0.022 (I 1) H (161) 0.5689 0.6170 - 0.0821 0.016 (10) H (162) 0.4046 0.5736 - 0.1113 0.019 (10) H (211) 0.2628 0.7569 0.0865 0.011 (9) H (221) 0.3347 0.5762 0.1613 0.016 (10) H (222) 0.4920 0.6349 0.1909 0.050 ( 15) H (231) 0.3461 0.6627 0.2926 0.014 (9) H (232) 0.2217 0.1274 0.2304 0.027 (12) H (241) 0.3499 0.8831 0.3059 0.018 (10) H (242) 0.5027 0.8297 0.2879 0.011 (9) H (251) 0.4468 0.9996 0.2049 0.027 (1 1) H (252) 0.2873 0.9474 0.1735 0.046 ( 15) H (261) 0.433 I 0.9 144 0.0730 0.015 (10) H (262) 0.5537 0.845 I 0.1353 0.010 (9)

b ‘” --

Fig. I Monoanions tetramer formed by hydrogen bonds between phosphonate groups in crystal I. (Anion Ibis taken from the symmetry-related position (x. y + 1, z). This is consistent with the text, where anion Ib (from x, y, z) chelates the K’ cation. The symmetry codes are the same as in Table 4. The thermal ellipsoids are represented at 50% probability level.

148

Table 3

.I. Mazurek, T. Lis / Journul of Molrrular Structure 474 (1999) 143-155

Principal interatomic distances, bond angles and torsion angles for I, II. and III (,&O). (The values marked with an asterisk refer to hydroxyl 0 atoms)

Ia Ib IIa IIb III

P(l)-O(1) 1.495( 1) P( 1 )-O(2) 1.508(2) P( 1 )-O(3) 1.574(2)* P(l)-C(1) 1.826(2) 0(4)-w) 1.218(2) C( 1 )-C(2) 1 so l(2) C(2)-C(3) 1 SOO(2) O( 1 )-P( 1 )-O(2) 117.8(l) O(l)-P(l)-O(3) 111.9(l) O(2)-P( 1 )-O(3) 108.0( 1) O(l)-P(I)-C(1) 108.9(l) O(2)-P( I )-C( 1) 105.6(l) O(3)-P( I )-C( 1) 103.5(l) C(2)-C( 1 )-P( 1) 111.3(l) O(4)-C(2)-C(3) 121.1(2) O(4)-C(2)-C( I) 120.9(2) C(3)-C(2)-C( 1) I 18.0(2) O( 1 )-P( 1 )-C( 1)-C(2) - 43.6(2) O(2)-P(l)-C(l)-C(2) - 171.1(l) O(3)-P( I)-C( 1)-C(2) 75.6(l)* P( 1 )-C( 1 )-W-O(4) 92.0(2) P( 1 )-C( 1 )-C( 2)-C(3) - 87.1(2) Coordination sphere of the K+ cations in crystal I K( 1 a)-0( 1 a) 2.747(I) K( 1 a)-O(4a) 2.766(I) K(la)-O( 1 b) 2.744(I) K( 1 a)-O( 1 b)’ 2.695( 1) K( 1 a)-O(3a)” 2.725( 1) K( la)-O(2b)“’ 2.771(l) K(lb)-O(lb) 2.779(l) K( I b)-O(4b) 2.867( 1) K( 1 b)-0( I a) 2.788( 1) K(lb)-O(la)’ 2.742( 1) K( I b)-O(3b)” 2.681(l) K( 1 b)-O(2a)’ 2.778( 1)

1.496( I ) 1.574(2) * 1.513(l) 1.8 I9(2) 1.214(2) 1.504(2) 1.499(2) 113.0( 1) 115.9(l) 109.2( I ) 108.4(l) 100.5(l) 108.7( 1) 110.3(l) 121.7(2) 120.6(2) 117.8(2) - 52.9(l) - 171.6(l)*

73.9( I ) 97.0(2) - 81.4(2)

1.561(2)* 1.503(2) 1.490(2) 1.815(3) 1.215(3) 1.488(4) 1.48514) 1 I 1.0(2) 112.0(2) 115.3(l) 100.7(2) 105.8(2) 1 10.9(2) 117.5(2) 121.2(3) I 19.6(3) 1 19.3(3) - 54.0(3)* - 169.6(2)

64.7(3) 117.0(3) - 63.4(3)

1.492(2) I .496(2) 1.557(2) * 1.817(3) 1.2 12(3) 1.503(4) 1.475(4) 116.5(l) 110.6(2) 107.3(2) 108.0(2) 108.8(2) 105.0(2) 1 11.0(2) 121.4(3) 120.7(3) 117.8(3) - 70.1(3)

162.6(2) 48.0(3)* 74.0(3) - 104.3(3)

Symmetry code: (i) 1 - x, v, 1.5 - z; (ii) x, J - 1, z; (iii) x. ~ J, 0.5 + z; (iv) x, I + y, z; (v) x, 1 - y,z - 0.5

Geometric parameters of the dicyclohexylammonium cation in III N( I)-C(21) 1.498(5) N(l)-C(l1) 1.503(5) C ,,l”g, -C iTI”@, 1.516(6)-1.530(6) C(21)-N(l)-C(I I) 1 l&7(3) N(I)-C(1 I)-C(12) 112.4(3) N(l)-C(ll)-C(l6) 107.9(3) N( l)-C(21)-C(26) 113.0(3) N( I)-C(21)-C(22) 108.0(3) C Irl”p) -C -C,,,,,, Inn&) 110.0(4)-l 12.6(4)

1.483(3) 1.508(3) I .566(3) * 1.83 l(4) 1.220(5) I .49 l(6) 1.486(6) Il7.0(2) 108.5(2) I 10.6(2) 108.3(2) 106.6(2) 105.2(2) 113.4(3) 121.1(4) 12 1.0(4) I 17.9(4) - 38.9(4) - 165.6(3)

77.0(4)* 106.3(4) - 72.8(5)

Table 4

.I. Mazurek, T. Lis / Journal of Molecular Structure 474 (1999) 143-155 149

Geometry of proposed hydrogen bonds.

D-H...A D-H (A) H...A (A) D...A(A) DHA(“)

I 0(3a)-H(3a). .0(3b)” 0(2b)-H(2b)...0(2a)” C(3a)-H(3la)...0(4a)“’ C( la)-H( 12a). ..0(4b)“” C(lb)-H( 1 lb)...0(4a)” C(3b)-H(3 lb). .0(4b)” Symmetry code: (iv) x, I + y, z; (vi) 1 - (ix) x, - .v, z - 0.5; (x) 0.5 - x, 0.5 - II

0.79(4) 0.83(3) 0.93(4) 0.96(2) 0.92(2) 0.9 I(3) x, y - I ) 1.5 4’, 1 - z.

O(la)-H(la)...0(2b)’ 0.86(4) 0(3b)-H(3b)... O(2a) 0.77(4) N( I)-H( I 1). .0(2a)’ 0.9 l(4) N( I)-H( 12). .O( I b)” 0.90(4) N( I)-H(l3)...0(3a) 0.92(4) N( I)-H( 14). .0(2b)“’ 0.92(3) N(2)-H(2l)...O(lb)” 0.89(4) N(2)-H(22)...(0(4b) 0.73(4) N(2)-H(23)...0(3a)’ 0.89(5) N(2)-H(24)...0(4a)” 0.86(4) C(la)-H(lla)...0(4a)” 0.90(3) C(3a)-H(33a)...0(4a)“’ 1.12(6)

- z;

1.71(4) 2.497(2) 169(4) 1.72(3) 2.536(2) 170(3) 2.56(4) 3.337(2) 142(3) 2.81(3) 3.536(2) 133(2) 2.60(3) 3.372(2) 141(2) 2.71(3) 3.407(2) 134(3)

(vii) 0.5 - x, 0.5 + J. I .5 - z; (viii) x, 1 - y. 0.5 + i:

1.74(4) 1.81(4) 1.99(3) 1.91(4) 1.91(4) 1.99(3) 1.91(4) 2.35(4) I .99(5) 2.06(4) 2.75(4) 2.72(6)

2.591(3) 2.574(3) 2.874(3) 2.800(3) 2.823(3) 2.863(3) 2.786(4) 2.967(4) 2.808(4) 2.900(4) 3.644(4) X334(5)

169(3) I69(3) 162(3) 170(3) 170(3) 159(3) 166(3) 144(4) 151(5) 164(3) 173(3) I14(3)

Symmetry code: (i) 1 - x. 1 - I‘. 2 - z; (ii) x, y + 1. i.; (iii) - x, 1 - y, 2 - z; (iv) I - x, - T, 2 - z; (v) x. ?; - I,;; (vi) 2 - x, 1 - .v, 1 - 2; (vii) 1 - x, I - .v, 1 - i III 0(3)-H(3). .0(2)’ 0.66(5) 1.98(5) 2.63 l(5) 171(6) N(l)-H(l)...0(2) 1.07(6) 1.84(6) 2.828(5) 152(5) N(l)-H(2)...0(1)” 0.92(5) 1.82(5) 2.735(5) 174(4) C(l I)-H(1 Il)...O(4)” I .oo 2.65 3.594(5) 157 C(12)-H(121)...0(4)” 0.99 2.64 3.469(5) 141 C(26)-H(261). ..0(4)” 0.99 2.57 3.414(5) 143 Symmetry code: (i) - x, I - y, - z; (ii) 1 - x. I - v, - 2; (iii) x, I + y, z

(Aldrich) was diluted in 50 ml of dry CC14 and cooled to - 78°C on the acetone/liquid nitrogen bath. Then 6 ml (two equivalents) of trimethylsilyl iodide were added dropwise under a nitrogen atmosphere. The mixture was stirred on a magnetic stirrer under nitrogen at this temperature for 0.5 h. Then the solu- tion was left to warm to room temperature, evaporated to dryness on the rotary evaporator, dissolved in 20 ml of water, and stirred for 0.5 h. The solution was evaporated to dryness on the rotary evaporator and dissolved in 20 ml of acetone. An equimolar ratio of cyclohexylamine (1.18 g) was added. The white precipitate of cyclohexylammonium (2-oxopropyl) phosphonate was collected on a Shot funnel and washed three times with acetone (yield 2.12 g, 85%). (MS gave single peak 137 M-).

The crystals of I and II were obtained as follows: 0.5 g of cyclohexylammonium (2-oxopropyl) phos- phonate was dissolved in 5 ml of water and passed through the DOWEX 50 ion-exchange resin (H+ form, 100 mesh, Acres Organics). An equimolar ratio of KHC03 or NH4HCOj was added to the concentrate eluate and stored in a refrigerator. Colour- less crystals were obtained after a few days.

All crystals were examined by oscillation and Weissenberg photographs. The other crystallographic measurements were performed on a Kuma KM 4 computer-controlled K-axis diffractometer with graphite-monochromated MO K, radiation. The data for I and III were collected at 120 K using the Oxford Cryosystem cooler. The stability of intensities was monitored by measurement of three standards every

150 J. Mazurek. T. Lis / Jountul of Molecular Strwture 474 (19%‘) 143-155

04b

04a

Fig. 2. Monoanions tetramer formed by hydrogen bonds between phosphonate groups in crystal II. The thermal ellipsoids are represented at 30% probability level.

100 reflections. The data were corrected for Lorentz atoms. All H-atoms (except for cyclohexyl rings in and polarization effects. No absorption correction was III) were found on the Fourier difference maps and applied. Experimental details are given in Table I. All refined isotropically. The H-atoms from the cyclo- structures were solved by direct methods using the hexyl rings were included from geometry and refined SHELXS-86 program [12], and refined by a full- isotropically. The scattering factors were taken from matrix least-squares technique using SHELXL-93 Ref. [ 141. The final atomic coordinates and equivalent [ 131, with anisotropic thermal parameters for non H- thermal parameters are listed in Table 2.

Fig. 3. Monoanion dimer formed by hydrogen bonds between phosphonate groups in crystal III. The thermal ellipsoids are represented at 50% probability level.

.I. Muzurek. T. Lis /Journal of Molrculur Structure 474 (1999) 143-155

~1 /

, / 0 [lb /‘, ’ __--

ors 03 111

02

Fig. 4. A comparison of structures of monoanions: Ia (solid line), Ib (open line), IIa (solid dashed line), IIb (dashed line) and III (dotted line). The common reference points are P(l), C(I) and C(2) atoms. The hydroxyl groups are marked as 0.

151

3. Results and discussion

3.1. Molecular geometry of the anions

The crystals studied contain the same anion in monoionized state in three chemical environments: potassium (I), ammonium (II) and dicyclohexylam- monium (III) cations. The geometric parameters of the anions are given in Table 3. The crystals of I and II contain two crystallographically independent anions denoted a and b. The geometries of the anion in the crystals differ in the orientation of the hydroxyl group, which is + gauche for Ia, IIb and III, while being nearly antiperiplunar for Ib and - gauche for IIa, with respect to the C(C0) atom. In all cases the overall structure of the monoanion (Figs. l-3) is similar, with the phosphonate group projected out of the plane of the ketone backbone. A comparison of the monoanions with marked hydroxyl groups is presented in Fig. 4. The orientation of the phosphonic group in relation to the 2-oxopropane backbone may be described by the torsion angles P( la)-C( la)- C(2a)-O(4a) and P(la)-C( la)-C(2a)-C(3a) in Ia, and the corresponding angles in the residual part of the anion in the rest of the crystals. The value of these

II n

04a

Fig. 5. The cubane-like structure formed by K+ cations and phosphonate 0 atoms in crystal I. (The symmetry codes are the same as in Table 3).

.I. Mazurek, T. Lis / Journnl of Molecular Structure 474 (1999) 143-155

b

Fig. 6. The crystal packing of I

torsion angles is around 90” (Table 3), which shows that the phosphonate group prefers the position almost perpendicular to the rest of molecule. The C-P bond lengths [ 1.8 15(3)- 1.83 1(4)A] are slightly longer than those observed in nonsubstituted alkyl phosphonates [ 1.77-1.80 A] with the phosphonate group in the monoionized state [ 15,161; this is likely to be caused by the substitution of the beta position by the strong electronegative carbonyl 0 atom. The same effect is even more pronounced for the other phosphonate anions with the carbonyl oxygen atom substituted in the (Y position to the phosphonate group, such as (l- oxoethyl) phosphonate [ 1.859(3$] [9], (1 -oxopropyl) phosphonate [ 1.847(7)- 1.861(6#] and (1-oxobutyl) phosphonate [ 1.826(4)-l .835( 1 l)A] [lo].

In the phosphonate group, two terminal 0 atoms (denoted as 01 and 03) are gauche and one 0 atom (02) is nearly antiperiplanar with respect to the

C(C0) atom. This is similar to the structures of the phosphate esters [17]. The phosphonate group is distorted from a regular tetrahedron. The largest angle is that formed by terminal unprotonated 0 atoms, while the angle C-P-O(H) is the smallest. The deformation difference results from the position of the hydroxyl group in relation to the C(C0) atom. The O-P-O angle is largest for the anions with the hydroxyl group in - gauche (Ia, IIb and III), and smallest for the antiperiplanar orientation (Ib). The smallest angles C-P-O(H) are observed for anions with the hydroxyl group in untiperiplanar or -gauche position with respect to the C(C0) atom.

3.2. Crystal structures of the salts

In crystal I two symmetry-independent K+ cations are coordinated in a similar way. Both cations are

.I. Mazurek, T. Lis / Journal of Molecular Structure 474 (1999) 143-155 153

Fig. 7. The crystal packing of II.

hexacoordinated and chelated by one anion through the carbonyl O(4) and phosphonate O(1) atom. The co-ordination polyhedron is completed by phospho- nate 0 atoms yielding strongly distorted octahedrons. The cations are arranged in tetramers bridged through phosphonate 0( 1) atoms forming a cubane-like struc- ture unusual for Kf cations (Fig. 5). A similar kind of potassium-cation arrangement was previously observed only for structures of three salts [ 18-201. The cations and coordinated anions form a polymeric layer parallel to the bc plane. The inner part of the layer is constituted by a cation bilayer while the outer part is formed by coordinated anions. The layers are linked by weak C-H.. .O hydrogen bonds (Fig. 6 and Table 4).

In II, the crystals are built from two symmetry- independent NH: cations and two symmetry-inde- pendent phosphonate anions. Each NH: cation is linked to four different anions by hydrogen bonds. The network of extensive cation...anion and anion . ..anion hydrogen bonds occurring in the crystal

forms a three-dimensional polymeric structure (Fig. 7 and Table 4).

The crystals of III are built from dicyclohexylam- monium cations and phosphonate anions. The dicy- clohexylammonium cation has a similar structure to that observed earlier [21-281, with the chair confor- mation in both cyclohexyl rings, the C-N-C angle opened up to 118.7(3)“, and a similar orientation of cyclohexyl rings with respect to the ammonium group. The hydrogen-bonded anion dimers are sepa- rated by the bulky dicyclohexylammonium cations. The ammonium H-atoms are linked to the phospho- nate groups by N-H.. .O hydrogen bonds. The cations hydrophobic cyclohexyl rings are directed outside of the layer formed by an extensive network of hydrogen bonds parallel to the ab plane (Fig. 8 and Table 4).

3.4. Hydrogen bonds

In the crystals under study, three types of hydrogen bond could be distinguished (Table 4):

J. Mrrzurek, T. Lis / Jounzcrl of Molrcular Structure 474 (1999) 143-155

Fig. 8. The crystal packing of III. The figure show one hydrogen-bonded polymeric layer parallel to the ab plane

(a) intermolecular O-H.. .O between the phospho- nate 0 atoms (very strong in I and strong in II and III); (b) intermolecular N-H...0 between the nitrogen hydrogens from the cation and phosphonate 0 atoms (in II and III) or the carbonyl 0 atoms (in II); (c) weak intermolecular C-H.. .O interactions between the methyl or methylene hydrogens and the anion carbonyl 0 atoms (in all of the crystals).

There are two types of intermolecular hydrogen bonds formed through the phosphonate 0 atoms. In the crystals of III the anions form dimers (Fig. 3) by the hydrogen bonds through the symmetry centre. Such an arrangement has been observed in several different phosphonate crystals [29]. In the crystals of I and II the anions are arranged in hydrogen-bonded cyclic tetramers (Figs. 1 and 2). Such an arrangement of the phosphonate monoanions is rather rare [29].

The second type of hydrogen bond is observed for

the interaction between the dicyclohexylammonium and ammonium hydrogens and the 0 atoms from the phosphonate (in II and III) or carbonyl 0 atoms (in II). In the case of III the ammonium H atoms form hydrogen bonds with the phosphonate 0 atoms, which are stronger acceptors than carbonyl 0 atoms. In the case of II these hydrogen bonds are formed with phos- phonate as well as carbonyl 0 atoms.

The third type of intermolecular non-bonded contacts present in these crystals is the weak C- H...O hydrogen bonding. In the crystals of I and II these contacts occur between methyl and methylene H atoms from the anion and the carbony atoms. In III crystals they occur between methylene hydrogen atoms from the cations and carbonyl 0 atoms.

Acknowledgements

The authors would like to thank Prof. P. Kafarski from the Technical University of Wrodaw for the

J. Mazurek, T. Lis / Journal of Molecular Structure 474 (1999) 143-155 I.55

generous gift of compound III. Financial support from the Polish State Committee for Scientific Research under grant No 3 TO9 002 013 and the University of Wroclaw grant No 2212/PB/WCH/97 is gratefully acknowledged.

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PI [31

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[61

[71

181 [91

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11 II [I21

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