Indi an Journal of Chemistry Vol. 41A, July 2002, pp. 1363- 1368

Synthesis and crystal structure of two extensively hydrogen bonded network of eu(II)

Sudipta Dalai, Partha Sarathi Mukherjee+, Steven Geib+ & Nirmalendu Ray Chaudhuri*

Department of Inorgan ic Chemistry, Indian Association for the Culti vation of Science, Jadavpur, Kolkata 700 032, India

Received 23 October 2001; revised 20 March 2002

Two new Cu(IJ) coordination polymers of higher dimensionali ty, [CU(L')2J(L:!), [L,= N-(2-hydroxyethyl)ethylenediamine, L2= fumarate dianionJ, (1) and [Cu(L3)2(H20)2JCL4), [L3= 1-(2-aminoethyl)pyrroLidine, L4= squarate dianionJ, (2), have been synthesized and characterized by X-ray single crystal analysis. Complexes (1) and (2) form 3D and 2D network respectively through extensive hydrogen bonding.

A key objective in the emerging field of crystal engineering is the control and manipulation of weak interactions in order to guide the properties of the bulk material 1-6. Such kind of materials attain a special place due to their potential multi-dimensional applications in the field of catalysis 7, non-linear optics8, electrical conductivi ty9, molecular recognition 10 and molecular sieves II. Supramolecular inorganic/organic hybrid materials have so far been constructed through two principal philosophies 12. Primarily, coordination polymers can be constructed by assembling transition metal complexes using coordinate covalent bond 13. These type of materials are usually constructed by applying bifunctional ligands such as 4,4'-bipyridine as linkers between adjacent metal atoms I4-16. Alternately, wide variety of extended networks can be obtained by connecting the metal complexes via non-covalent forces (notably hydrogen bonding)1 7-21 which is the approach we have followed in the present work.

In this paper, we report the synthesis and crystal structure of two new high dimensional extensively hydrogen bonded Cu(Il) coordination polymers, [Cu(LI)2](L2), [LI= N-(2-hydroxyethyl)ethylenediamine, L2= fumarate dianion] , (1) and [Cu(L3h CH20h](L4), [L3= 1-(2-aminoethyl)pyrrolidine, L4= squarate dianion, (2)]. using two different terminal amine ligands and fumarate/squarate as building blocks respectively.

Corresponding author: Fax: +9: -33-473 2805; e-mail : icnrc@ mahendra. iacs. res. in +Department of Chemistry, Kalna College, Kalna 713409, India *Department of Chemistry, 920 CSC, University o f Pittsburgh, Pittsburgh, PA 15260, USA

Materials and Methods High purity N-(2-hydroxyethyl)ethylenediamine

(L I) and 1-(2-aminoethyl)pyrrolidine (L3) were purchased from Aldrich Chemical Company Inc., fumaric acid (L2H2) and 3,4-dihydroxy-3-cycIobutene-l,2-dione (L4H2) were purchased from Lancaster and used as received. All other chemicals used were of analytical grade. Elemental analyses were done using a Perkin-Elmer 240C elemental analyzer. IR spectra (4000-400 cm-I) were recorded on a Perkin-Elmer IR783 where KBr / Nujol was used as medium/reference material.

Preparation of complexes

[Cu(L,h}(L2) (1) N-(2-hydroxyethyl)ethylenediamine (2 mmol) in

methanol (5 cm3) was added to a methanolic solution (5 cm3) of copper(Il) perchlorate hexahydrate (2 mmol, 0.74 g) with constant stirring. Aqueous solution (10 cm3) of Narfumarate (2 mmol) was added to the resultant solution, stirred for half an hour and then filtered . The blue filtrate was kept in a CaCh desiccator. After a few days, blue si ngle crystals of diffraction quality were obtained, yield, 70% [Found: C, 37.44; H, 6.93; N, 14.63. Calc. for CI2H260 6N4Cu : C, 37.4; H, 6.7; N; 14.5%]. IR: v (COO-),1370,1592 em-I; v (N-H), 2900 cm- I . ~

[Cu(L3h(H20h}(L4) (2) To a methanolic solution (5 cm3) of Cu(1I)

perchlorate hexahydrate (2 mmol, 0.74 g) was added 1-(2-aminoethyl)pyrrolidine (2 mmol) in methanol (5

1364 INDIAN J CHEM . SEC. A, JULY 2002

cm3). To this solution, an aqueous solution (10 cm3) of disodium salt of 3,4-dihydroxy-3-cyclobutene-l,2-dione (2 mmol) was added and stirred for half an hour. The resulting green solution was filtered and suitable single crystals of diffraction quality were obtained by slow evaporation of the solution , yield, 74%, [Found: C, 43.72 ;H, 7.39;N, 12.85. Calc. for C1 6H320 6N4CU: C, 43.6; H, 7.0; N; 12.7%J IR: v(C=O), 1762 cm-I ; v(N-H) , 2900 cm- I ; v(O-H), 3400-3300 cm- I .

Data collection, structure solution and refinement X-ray intensities for complex (1) were recorded on

a Siemens P3 diffractometer with graphite-monochromated Mo-Kcx (1.= 0.71073 A) radiation. A total of 2716 independent refl ections were carried out, only 1159 number of reflections, for which 1>2a (/), were used in structure analysis. Unit-cell dimensions

were derived from the least-squares fit of the angul ar settings of 25 reflection with 21 °

DALAI et al.: HYDROGEN BONDED NETWORK OF Cu(II) 1365

employing the CD-28 scan method; absorption correction was applied. The structure was refined using a full matrix refinement procedure (SHELXTL97)23, with anisotropic thermal parameters assigned to all non-hydrogen atoms . All hydrogen atoms were observed in the difference map. At convergence Rl = 0.0341 , wR2 = 0.0869, for 2761 unique reflections and 128 parameters, [2890 reflections collected, R(int) == 0.0561, 2195 with I> 20- (I)] . Residual s = 0.422, -0.636 e/A3.

The positional parameters along with equivalent isotropic thermal parameters for the non-hydrogen atoms in complexes (1) and (2) are given in Table (1) and Table (2) respectively .

Crystal data The cell constants and crystallographic data for

complex(1) are: Mol. formula C1 2H2606N4CU; mol. wt. 385.92; orthorhombic Pbcn; a = 9.4860(19) A; b = 13.629(3) A; c = 12.660(3) A; V = 1636.7(6) A3; z = 4; F(OOO) = 812; P eal = 1.566 g cm·3 and for complex (2) : Mol. formula C 16H3206N4CU; mol. wt. 440.01; monoclinic P21/n ; a = 8.0170(10) A; b = 11.328(2) A; c = 10.6790(10) A; V = 949.9(2) A3; Z = 2; F(OOO) = 466; P eal = 1.538 g cm·) .

Results and Discussion

Description of the structure An ORTEP view of the complex (1) with the atom

Fig. I - An ORTEP view of the complex (I ) with the atom labelling scheme.

labelling scheme is shown in Fig. 1. The Cu(II ) cationic complex resides on a crystallographic 2-fold axis and the fumarate dianion resides on a crystallographic inversion site. The geometry around the Cu(II) is square planar with CuN4 chromophore [(Cu(1)-N(1) 2.0188(17) A, Cu(1)-N(2) 2.0574(14) A)] (Table 3). The hydroxyamine ligand acts here as a bidentate (NN) chelating ligand. This monomeric unit with extensive H-bonding through fumarate counteranion results a 3D network. Final difference Fourier syntheses show only chemically insignificant electron density. 3D extended network is shown in Fig. 2.

The crystal structure of complex (2) is composed of octahedral copper(II) complex and squarate anion

Table 3 -Selected bond lengths[A] and angles [0] for [Cu(L1h](L2) (1)

Cul-N2 2.0574(14) Cui-Nt 2.0188( 17) Cul-03 2.4602(13) C4-C5 1.495(2) 03_b-Cul-N2 87.58(5) 03-Cul-N2 77.63(5) NI_b-Cul-N2 174.64(6) NI-Cul-N2 83.31(6) N2-Cul-N2_b 96.04(5) 03-Cul-NI 97.45(5) N l_b-Cul-N2_b 83.31(6)

Table 4-Selected bond lengths[A] and angles [0] for [Cu(L)h(H20h](L4) (2)

Cu-N(1) Cu-N(2) Cu-O(l) O(2)-C(7) O(3)-C(8) N( I )-C( I) N(2)-C(2) N(2)-C(3) N(1 )-Cu-N(1)# I N( I )-Cu-N(2)# I N(1 )-Cu-N(2) N(2)# I-Cu-N(2)

1.992(1 ) 2.140(1 ) 2.587(2) 1.244(2) 1.250(2) 1.476(2) 1.480(2) 1.490(2)

180.0 95 .66(6) 84.34(6)

180.0

N(2)-C(6) C(I)-C(2) C(3)-C(4) C(4)-C(5) C(5)-C(6) C(7)-C(8) C(7)-C(8)#2

N(1 )-Cu-O(1) ....

N(1)# I-Cu-O( I) N(2)# I-Cu-O(1) N(2)-Cu-O(I)

Symmetry transformations: # 1 -x,-y+ I ,-z; #2 -x+ I ,-y+ I ,-z+ I

1. 494(2) 1.508(3) 1.507(3) 1.537(3) 1.529(3) 1.465(3) 1.471 (3)

88.98(6) 91.02(6) 95.78(6) 84.22(6)

1366 INDIAN J CHEM. SEC. A, JULY 2002

Fig. 2 - 3D extended network of hydrogen bonding in complex (1).

Fig. 3 -ORTEP drawing of complex (2). (thermal ellipsoids at 40% probability level).

(Fig. 3). The metal, located on a centre of sy mmetry, exhibits axial distances with water molecules [(Cu-O( I) 2.587(2) A] which are signi fIcan tly longer with respect to the equatorial Cu-N( I) and Cu-N(2) ones, with the amino and pyrrolidine nitrogen donors, respecti vely [1.992(1), 2.140(2) A] (Table 4). The structure determination discloses a 20 network of hydrogen bonds extending along the crystallographic axis b and the diagonal of plane alc, connecting the complexes and the counteranions (Fig. 4). In fact , the two crystallographic independent oxygens of the squarate anion are H-bonded to the coordinated water molecules 0(1) and to the amino ni trogens N(1 ) of adjacent Cu complex, in such a way that the H-bonds form a quadrilateral figure . The data for hydrogen bonds for [Cu(L, hCL2) and [eu (L3h ](L4) are

Table 5 - Hydrogen bonds (A ,O) for [Cu(L) zl(Lz) (1)

D-H-A D-H H-A D-A D-H-A

NI - HI# .. OI 0.83(2) 2. J 4(2) 2.924(2) 157.8( 18)

NI - H2# .. 02 0.83(2) 2.26(2) 3.064(2) 163.0( 19)

N2- H2N .. OI 0.86(2) 2.07(2) 2.878(2) 155.8( 19)

03- H30 .. 02 0.89(2) 1.76(2) 2.6195( 18) 163(2)

C6--H6A. .02 1.04(2) 2.59(2) 3.459(2) 140.6( 15)

DALAI el al.: HYDROGEN BONDED NETWORK OF Cu(lI) 1367

Fig. 4- A 20 network of hydrogen bonds in complex (2) ex tending along the crystallographic axis b and the diagonal of plane alc, connecting the complexes and the counteranions.

D-H-A D-H H-A

O I- HIA .. 02 0.9353 1.8407 OI-HIB .. 03 0.9356 1.8989 N I- HI C..02 0.8998 2. 1448 N I- HID .. 03 0.9005 2. 1456

C2-H2A .. O I 0.9698 2.5337

C3- H3A .. O I 0.9702 2.574 1

presented in Table 5 and 6.

Supplementary data Tables containing li stings of positional parameters,

thermal parameters, a ll distances and angles for complexes( l ) and (2) are avai lab le from the authors.

Acknowledgement The authors are thankfu l to the CSIR, New Delhi ,

fo r financial support.

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