engleski

Two bis Bidentate Complexes of Copper(II) and Tryptophane

Transition metal complexes have significant roles in many biological systems and for over four decades their structures have been of considerable interest and importance in coordination chemistry. Studies of these relatively simple complexes may enhance our understanding of the more complicated metalloproteins. For many iron containing proteins there are parallel copper dependant analogues with comparable functions. Particular interest is set on metal-protein interactions. Strong and kinetically inert bonding allows the metal ion to be retained in the protein without having to be bound by a macrocycle. In case of copper such interactions can be accomplished with histidine, tyrosine and triptophane moieties. The structural information on those molecules in solid state are rare due to the problems of solubility and preparation of good quality monocrystalline specimens. The crystal and molecular structures of cis and trans bis bidentate copper– triptophanate complexes were determined. Crystal data. (I) trans Cu(Trp)2 - C22H18O2CuN, Mr = 314.38, monoclinic, space group P 21, a = 9.4570(10) Å ; , b = 5.1470(10) Å ; , c = 20.3250(40) Å ; ,  = 96.705(16)  , V = 982, 56(19) Å ; 3, Z = 2, Dc = 1.589 g cm 3, F(000) = 486,  (MoK ) = 0.71073 Å ; ,  (MoK ) = 1.15 mm 1, R = 0.0856, wR = 0.1429 for 2366 [Fo > 4 (Fo)] out of the 4738 reflections and 321 variable parameters. (II) cis [Cu(Trp)2(dmso)](dmso)3(H2O) - C30H48O9N4CuS4, Mr = 533.70, orthorhombic, space group P 212121, a = 9.2252(13) Å ; , b = 13.5370(13) Å ; , c = 29.6839(25) Å ; , V = 3706.97() Å ; 3, Z = 4, Dc = 1.434 g cm 3, F(000) = 1684,  (MoK ) = 0.71073 Å ; ,  (MoK ) = 0.87 mm 1, R = 0.0374, wR = 0.0833 for 11456 [Fo > 4 (Fo)] out of the 12 939 reflections and 553 variable parameters. The crystals of (I) are built of molecules that are linked into puckered chains via short Cu– O22(i) contacts {; ; 2.511 Å ; [i = – x, ½ ; +y, – z]}; ; and moderately strong N21– H21A• • • O21(i) hydrogen bonds (2.921 Å ; ). The chains of molecules are held together by N21– H21B• • • O12(ii) hydrogen bonds {; ; 3.069 Å ; [ii = 2– x, ½ ; +y, 1– z]}; ; . The crystals of (II) are unstable and the data were collected at 100 K. The crystal and molecular structure of compound (II) is fairly unusual. The coordination number of the copper(II) ion is five - two trp ligands in cis arrangement creating puckered chelate rings and one oxygen bonded dmso molecule at the apex. The indole moieties of the trp ligands are almost perpendicular to the chelate plane of the molecule and are bent on the same side of the molecule so it reminds of a dragonfly. The complex molecules are linked into chains via moderately strong hydrogen bonds formed by N11 and N21 ligating atoms and carboxylate O11 and O12 atoms of a symmetry related molecule {; ; N11– H11B• • • O11(i) 3.000 Å ; and N21– H21A• • • O12(i) 2.993 Å ; [i = – 1/2– x, – 1/2– y, 2– z] }; ; . Those chains of molecules are interlinked via water molecule hydrogen bonds O71– H71B• • • O12(i) 2.878 Å ; and O71– H71A• • • O22(ii) 2.857 Å ; [ii = – 1+x, y, z] and hydrogen bonding contacts of the dmso molecules. One of dmso molecules is placed between the indole rings and is bonded to N11 and N21 atoms through two moderately strong hydrogen bonds (N11– H11A• • • O61, 2.857 Å ; and N21– H21B• • • O61, 3.024 Å ; ) and is disordered. The second dmso molecule is bonded to the one indole moiety of the complex molecule through a weak C18– H18• • • O51 (3.390 Å ; ) hydrogen bond and serves as a bridge to the symmetrically related complex molecule via N22(i)– H2(i)• • • O51 hydrogen bond ; {; ; 2.789 Å ; [i = – 1/2– x, – 1/2– y, 2– z]}; ; . Fourth dmso molecule is placed close to another indole moiety effectuating dispersive contacts to it through its methyl groups and is hydrogen bonded to the symmetrically related complex molecule {; ; N12(iii)– H1(ii)• • • O41 ; 2.840 Å ; [iii = – 1/2– x, – y, 1/2+z].

copper(II); tryptophane; self-assembling

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