Mono- and Polynuclear Guanine Complexes of Platinum(II). Syntheses and Crystal and Molecular Structures of Bis(9-methylguanine-N(7))bis(trimethylphosphine)platinum(II) Dinitrate and cyclo-Hexakis(9-methylguanine(-H)-N(1),N(7))hexakis(cis-bis(trimethylphosphine)platinum(II)) Hexanitrate

[Au2(μ-G)(μ-dmpe)]·(KBr)0.75·2H2O, a cyclic dinuclear gold(I) complex with an N3,N9-bridging coordination mode of guanine and aurophilic interactions: synthesis, X-ray crystal structure and luminescence properties (dmpe=1,2-bis(dimethylphosphino)ethane and G=guaninato dianion)

“…The charge balance indicates that guanine acts in a doubly deprotonated fashion. In keeping with this, the 1 H NMR spectrum of 1 shows no low field NH signals and the C8-H resonance undergoes an upfield shift of about 0.9 ppm with respect to its position in the spectra of metal complexes of neutral 9-methylguanine [29]. Similar upfield shifts of the C8-H proton have been observed for the tetrameric complex [{(g 5 -C 5 Me 5 )Ir(G)(H 2 O)} 4 ](CF 3 SO 3 ) 4 (G ¼ N7, N9-guaninate bridging dianion) [14] and for [Au 2 (l-HX)(l-dmpe)] (HX ¼ N3,N9-xanthinate bridging dianion) [27].…”

Cyclic, trinuclear PdII complex of cytidine with pronounced double cone structure

“…Only the co-ligands of the metal, if present, stick out from the plane. In contrast, reactions of cissquare-planar or cis-octahedral metal entities with nucleobases can lead to cyclic 3D-constructs reminiscent of clefts (head-tail dimers), trigonal vases (cyclic trimers), open boxes (cyclic tetramers) or wheels [6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23]. For example, with N(1) substituted cytosine, both dinuclear [7][8][9] and trinuclear [10,11] metal complexes have been prepared with cis-Pt II (NH 3 ) 2 , Pt II (en) and cis-Pt II (PR 3 ) 2 entities (R = Me or Ph).…”

Cyclic Tetranuclear and Hexanuclear Palladium(II) Complexes and Their Host−guest Chemistry

“…[1][2][3] Cyclic compounds of Pt(II) and Pd(II) were some of the first metals investigated because their square planar geometry provides corners for the formation of complex shapes. [4][5][6][7] Geometries include trimers, tetramers (molecular squares), pentamers, and hexamers 4,6,[8][9][10] as well as a few higher n-mers. 11 Typically these are held together by bridging N donor ligands.…”

“…23 The structure of the cyclic hexamer [(PMe 3 ) 2 Pt(9-methylguanine)] 6 (NO 3 ) 6 · 18H 2 O has been found to have S 3 symmetry with the 9-methylguanines located alternately above and below the plane of the six Pt(II). 8 The host-guest behavior of cyclic polynuclear complexes in solution has most often been investigated by NMR spectroscopy. In many cases the bridging ligands were aromatic or unsaturated molecules and ring currents or hydrophobic effects resulted in upfield shifts of the guest molecule resonances, frequently of 1 ppm or less.…”