PtII Atom Research Articles

Synthesis and crystal structures of three organoplatinum(II) complexes bearing natural arylolefin and quinoline derivatives

Three organoplatinum(II) complexes bearing natural arylolefin and quinoline derivatives, namely, [4-methoxy-5-(2-methoxy-2-oxoethoxy)-2-(prop-2-en-1-yl)phenyl](quinolin-8-olato)platinum(II), [Pt(C13H15O4)(C9H6NO)], (I), [4-methoxy-5-(2-oxo-2-propoxyethoxy)-2-(prop-2-en-1-yl)phenyl](quinoline-2-carboxylato)platinum(II), [Pt(C15H19O4)(C10H6NO2)], (II), and chlorido[4-methoxy-5-(2-oxo-2-propoxyethoxy)-2-(prop-2-en-1-yl)phenyl](quinoline)platinum(II), [Pt(C15H19O4)Cl(C9H7N)], (III), were synthesized and structurally characterized by IR and 1H NMR spectroscopy, and by single-crystal X-ray diffraction. The results showed that the cycloplatinated arylolefin coordinates with PtII via the carbon atom of the phenyl ring and the C=Colefinic group. The deprotonated 8-hydroxyquinoline (C9H6NO) and quinoline-2-carboxylic acid (C10H6NO2) coordinate with the PtII atom via the N and O atoms in complexes (I) and (II) while the quinoline (C9H7N) coordinates via the N atom in (III). Moreover, the coordinating N atom in complexes (I)–(III) is in the cis position compared to the C=Colefinic group. The crystal packing is characterized by C—H...π, C—H...O [for (II) and (III)], C—H...Cl [for (III) and π–π [for (I)] interactions.

Synthesis, crystal structure and anti-cancer activity of the complex chlorido-(η2-ethyl-ene)(quinolin-8-olato-κ2N,O)platinum(II) by experimental and theoretical methods.

The complex [Pt(C9H6NO)Cl(C2H4)], (I), was synthesized and structurally characterized by ESI mass spectrometry, IR, NMR spectroscopy, DFT calculations and X-ray diffraction. The results showed that the deprotonated 8-hy-droxy-quinoline (C9H6NO) coordinates with the PtII atom via the N and O atoms while the ethyl-ene coordinates in the η2 manner and in the trans position compared to the coordinating N atom. The crystal packing is characterized by C-H⋯O, C-H⋯π, Cl⋯π and Pt⋯π inter-actions. Complex (I) showed high selective activity against Lu-1 and Hep-G2 cell lines with IC50 values of 0.8 and 0.4 µM, respectively, 54 and 33-fold more active than cisplatin. In particular, complex (I) is about 10 times less toxic to normal cells (HEK-293) than cancer cells Lu-1 and Hep-G2. Furthermore, the reaction of complex (I) with guanine at the N7 position was proposed and investigated using the DFT method. The results indicated that replacement of the ethyl-ene ligand with guanine is thermodynamically more favorable than the Cl ligand and that the reaction occurs via two consecutive steps, namely the replacement of ethyl-ene with H2O and the water with the guanine mol-ecule.

Organoplatinum(II) Complexes Self-Assemble and Recognize AT-Rich Duplex DNA Sequences.

The specific recognition of AT-rich DNA sequences opens up the door to promising diagnostic and/or therapeutic strategies against gene-related diseases. Here, we demonstrate that amphiphilic PtII complexes of the type [Pt(dmba)(N∧N)]NO3 (dmba = N,N-dimethylbenzylamine-κN, κC; N∧N = dpq (3), dppz (4), and dppn (5)) recognize AT-rich oligonucleotides over other types of DNA, RNA, and model proteins. The crystal structure of 4 shows the presence of significant π-stacking interactions and a distorted coordination sphere of the d8 PtII atom. Complex 5, containing the largest π-conjugated ligand, forms supramolecular assemblies at high concentrations under aqueous environment. However, its aggregation can be promoted in the presence of DNA at concentrations as low as 10 μM in a process that “turns on” its excimer emission around 600 nm. Viscometry, gel electrophoresis, and theoretical calculations demonstrate that 5 binds to minor groove when self-assembled, while the monomers of 3 and 4 intercalate into the DNA. The complexes also inhibit cancer cell growth with low-micromolar IC50 values in 2D tissue culture and suppress tumor growth in 3D tumor spheroids with a multicellular resistance (MCR) index comparable to that of cisplatin.

SP-4-2]-(Acetonitrile-κN)chlorido[2-(4,6-diphenylpyridin-2-yl)phenyl-κ2 C 1,N]platinum(II)

The synthesis and crystal structure of the title PtII complex, [Pt(C23H16N)Cl(CH3CN)], based on the C,N-chelating 2,4,6-triphenylpyridine as the primary ligand, is described. The central PtII atom is in a distorted square-planar coordination environment. In the crystal, molecules are arranged via a metallophilic interaction between platinum atoms with a Pt...Pt contact of 7.052 (2) Å. In addition, a π–π interaction occurs.

The crystal structure of ((cyclo-hexyl-amino){(Z)-2-[(E)-5-meth-oxy-3-nitro-2-oxido-benzyl-idene-κO]hydrazin-1-yl-idene-κN 2}methane-thiol-ato-κS)(dimethyl sulfoxide-κS)platinum(II): a supra-molecular two-dimensional network.

The PtII atom in the title complex, [Pt(C15H18N4O4S)(C2H6OS)], exists within a square-planar NS2O donor set provided by the N, S, O atoms of the di-anionic tridentate thio-semicarbazo ligand and a dimethyl sulfoxide S atom. The two chelate rings are coplanar, subtending a dihedral angle of 1.51 (7)°. The maximum deviation from an ideal square-planar geometry is seen in the five-membered chelate ring with an S-Pt-S bite angle of 96.45 (2)°. In the crystal, mol-ecules are linked via N-H⋯O, C-H⋯O, C-H⋯N and C-H⋯π inter-actions into two-dimensional networks lying parallel to the ab plane. The conformations of related cyclo-hexyl-hydrazine-1-carbo-thio-amide ligands are compared to that of the title compound.

(Acetonitrile-κN)chlorido{2-[4-(3,5-difluorophenyl)-6-phenylpyridin-2-yl]phenyl-κ2 C 1,N}platinum(II)

The title compound, [Pt(C23H14F2N)Cl(CH3CN)], comprises of a PtII atom in a distorted square-planar coordination, defined by a C,N-chelating 4-(3,5-difluorophenyl)-2,6-diphenylpyridine ligand, a chlorido and an acetonitrile ligand. Hydrogen-bonding interactions between the H atoms of the 3,5-difluorophenyl ring and the acetonitrile ligand with Cl and F acceptor atoms of neighbouring ligands consolidate the packing.

(1,2,5,6-η)-Cycloocta-1,5-diene]bis(thiocyanato-κS)platinum(II)

In the title complex, [Pt(SCN)2(C8H12)], the PtII ion lies in a square-planar coordination geometry defined by the mid-points of the two π-coordinated double bonds of cycloocta-1,5-diene and two S-bound SCN− anions. The complex is disposed about a mirror plane passing through the Pt atom and the SCN− ligands, and bisecting the cycloocta-1,5-diene molecule. The room-temperature crystal structure of the title complex was previously reported in the orthorhombic space group Pna21 [Musitu & Garcia-Blanco (1984). Acta Cryst. A40, C101]. The low-temperature structure presented herein represents a different (higher symmetry) orthorhombic space group Pnma whereby the PtII atom lies on a mirror plane, lacking in the earlier study.

Trans-Bis[2-(aminomethyl)pyridine-κ2 N,N′]platinum(II)] bis(hexafluoridophosphate)

The title compound, [Pt(amp)2](PF6)2 [amp = 2-(aminomethyl)pyridine, C6H8N2], crystallizes in the space group P\overline{1} with a half of one [Pt(amp)2]2+ cation and one hexafluoridophosphate ion in the asymmetric unit. The PtII atom lies on an inversion centre and has a square-planar coordination sphere defined by two amino groups and two pyridine moieties of two 2-(aminomethyl)pyridine chelate ligands. The crystal structure of the title salt is composed of alternating rows of [Pt(amp)2]2+ cations and PF6 − anions. The crystal packing is stabilized by N—H...F hydrogen bonds between the amino groups and the hexafluoridophosphate anions. The PF6 anion is disordered over two sets of sites with an occupancy ratio of 0.744 (6):0.256 (6).

Crystal structure of cis-[1,2-bis-(di-phenyl-phosphan-yl)ethene-κ2P,P']di-chlorido-platinum(II) chloro-form disolvate: a new polymorph.

The title compound, [PtCl2(C26H22P2)]·2CHCl3 (I), is the third monoclinic polymorph of this platinum(II) complex involving the bidentate ligand cis-1,2-bis-(di-phenyl-phosphan-yl)ethyl-ene (cis-dppe) [for the others, see: Oberhauser et al. (1998a ▸). Inorg. Chim. Acta, 274, 143-154, and Oberhauser et al. (1995 ▸). Inorg. Chim. Acta, 238, 35-43]. The structure of compound (I) was solved in the space group P21/c, with one complex mol-ecule in the asymmetric unit along with two solvate chloro-form mol-ecules. The PtII atom is ligated by two P and two Cl atoms in the equatorial plane and has a perfect square-planar coordination sphere. In the crystal, the complex mol-ecule is linked to the chloro-form solvate mol-ecules by C-H⋯Cl hydrogen bonds and face-on C-Cl⋯π inter-actions. There are also weak offset π-π inter-actions present [inter-centroid distances are 3.770 (6) and 4.096 (6) Å], linking the mol-ecules to form supra-molecular sheets that lie in the bc plane.

Crystal structure of homodinuclear platinum complex containing a metal-metal bond bridged by hydride and phosphide ligands.

In the title compound, μ-di-phenyl-phosphido-μ-hydrido-bis-[bromido-(tri-phenyl-phosphane-κP)platinum(II)] diethyl ether monosolvate, [Pt2Br2(C12H10P)H(C18H15P)2]·C4H10O or [Pt2(μ-H)(μ-PPh2)Br2(PPh3)2]·(C2H5)2O, the PtII atoms are coordinated in a distorted square-planar arrangement, with one hydrido and one phosphido ligand bridging in a trans position. In the lattice, C-H⋯·O and C-H⋯π interactions are present. This complex has a total number of 32 electrons, 16 electrons for each PtII atom. One of the Br atoms is disordered over two positions in a 0.92:0.08 ratio.

Crystal structure of di-chlorido-(1,2-phenyl-enedi-amine-κ2N,N')platinum(II).

The PtII atom in the title compound, [PtCl2{(C6H4)(NH2)2}], lies on a twofold rotation axis and has a slightly distorted square-planar coordination environment defined by two N atoms of an 1,2-phenyl-enedi-amine ligand and two Cl- ions. In the crystal, the planar complex mol-ecules are stacked parallel to the c axis, resulting in a columnar structure. In a column, an infinite almost straight Pt⋯Pt chain is formed, suggesting weak metal-metal inter-actions [Pt⋯Pt = 3.3475 (8) Å]. The crystal packing is stabilized by a three-dimensional N-H⋯Cl hydrogen-bonding network between the amino groups and the Cl ligands of adjacent mol-ecules.

An acetonitrile solvatomorph of di-chlorido-(1,10-phenanthroline-5,6-dione)platinum(II).

In the title complex, [PtCl2(C12H6N2O2)]·CH3CN, the PtII atom lies in a slightly distorted square-planar arrangement defined by an N2Cl2 donor set. In the packed structure, columns of complex moieties are stacked such that the neighboring units are oriented at 180° and laterally displaced with respect to each other. This prevents any overlap of the phenanthroline rings and thus there is no possibility of any π–π inter­actions between aromatic rings.

Bis{2-[2,5-bis(pyridin-2-yl)-1H-imidazol-4-yl]pyridinium} tetracyanidoplatinate(II) tetrahydrate

The asymmetric unit of the title hydrated complex salt, (C18H14N5)2[Pt(CN)4]·4H2O, consists of one 2-[2,5-bis­(pyridin-2-yl)-1H-imidazol-4-yl]pyridinium cation, half a tetra­cyanidoplatinate(II) dianion, which is located about a crystallographic inversion center, and two water mol­ecules of crystallization. The PtII atom has a square-planar coordination environment, with Pt—CCN distances of 1.992 (4) and 2.000 (4) Å. In the cation, there is an N—H⋯N hydrogen bond linking adjacent pyridinium and pyridine rings in positions 4 and 5. Despite this, the organic component is non-planar, as shown by the dihedral angles of 10.3 (2), 6.60 (19) and 15.66 (18)° between the planes of the central imidazole ring and the pyridine/pyridinium substituents in the 2-, 4- and 5-positions. In the crystal, cations and anions are linked via O—H⋯O, O—H⋯N and N—H⋯O hydrogen bonds, forming a three-dimensional network. Additional π–π, C—H⋯O and C—H⋯N contacts provide stabilization to the crystal lattice.

Trans-Dichloridobis{dicyclohexyl[4-(dimethylamino)phenyl]phosphane-κP}platinum(II) dichloromethane disolvate

In the title complex, trans-[PtCl2{P(C6H11)2(4-Me2NC6H4)}2]·2CH2Cl2, the PtII atom is located on an inversion centre, resulting in a trans-square-planar geometry. Important geometric parameters are the Pt—P and Pt—Cl bond lengths of 2.3258 (6) and 2.3106 (6) Å, respectively, and the P—Pt—Cl angles of 89.64 (2) and 90.36 (2)°. The effective cone angle for the dicyclo­hex­yl[4-(dimethyl­amino)­phen­yl]phosphane unit was calculated to be 164°. The compound crystallizes with two dichloro­methane solvent mol­ecules; one of which is severely disordered and was treated using the SQUEEZE routine in PLATON [Spek (2009 ▶). Acta Cryst. D65, 148–155].

Cis-Dichloridobis[tris(4-chlorophenyl)phosphane-κP]platinum(II) acetonitrile monosolvate

The title compound, [PtCl2(C18H12Cl3P)2]·C2H3N, packs as monomeric units with a square-planar geometry around the PtII atom. The two tris­(4-chloro­phen­yl)phosphane ligands are coordinated in a cis orientation, with P—Pt—P and Cl—Pt—Cl angles of 99.36 (2) and 88.02 (2)°, respectively. In the crystal, C—H⋯N inter­actions are observed between the phenyl rings and the acetonitrile solvent mol­ecules.

Bis(μ-diisopropylphosphanido-κ2 P:P)bis[hydrido(triisopropylphosphane-κP)platinum(II)

In the centrosymmetric mol­ecular structure of the title compound [Pt2(C6H14P)2H2(C9H21P)2], each PtII atom is bound on one side to a phosphane ligand (PiPr3) and a hydrido ligand. On the other side, it is bound to two phosphanide ligands (μ-PiPr2), which engage a bridging position between the two PtII atoms, forming a distorted square-planar structure motif. The Pt⋯Pt distance is 3.6755 (2) Å. A comparable mol­ecular structure was observed for bis­(μ-di-tert-butyl­phosphanido)bis­[hydrido(triethyl­phosphane)platinum(II)] [Itazaki et al. (2004 ▶). Organometallics, 23, 1610–1621].

Dichlorido(2,3-di-2-pyridylpyrazine-κ2N1,N2)platinum(II)

The PtII ion in the title complex, [PtCl2(C14H10N4)], is four-coordinated in a distorted square-planar environment by two N atoms of a chelating 2,3-di-2-pyridyl­pyrazine ligand and two chloride anions. The pyridyl ring coordinated to the PtII atom is inclined slightly to its carrier pyrazine ring [dihedral angle = 13.5 (1)°], whereas the uncoordinated pyridyl ring is inclined considerably to the pyrazine ring [dihedral angle = 54.3 (2)°]. The dihedral angle between the two pyridyl rings is 59.2 (2)°. In the crystal, the complexes are assembled through inter­molecular C—H⋯N and C—H⋯Cl hydrogen bonds, forming a three-dimensional network. Intra­molecular C—H⋯N and C—H⋯Cl hydrogen bonds are also present.

{Bis[2-(diphenylphosphanyl)ethyl]phenylphosphane-κ3P,P′,P′′}[(Z)-8-mesitylcyclooct-4-en-1-yl]platinum(II) tetrafluoridoborate dichloromethane disolvate

In the title ionic compound, [Pt(C17H23)(C34H33P3)](BF4)·2CH2Cl2, the PtII atom adopts a square-planar coordination geometry with the large (Z)-8-mesityl­cyclo­oct-4-en-1-yl group occupying the fourth coordination site. The (triphos)Pt moiety and the mesityl group are attached to the cyclo­oct-4-ene motif at the 1- and 8-position in a syn configuration. The (BF4)− anion and one of the dichloromethane solvate molecules each are disordered over two sets of sites.

N-Benzyl-N-(diphenylphosphanylmethyl)pyridin-2-amine]chloridomethylplatinum(II)

In the mononuclear title complex, [Pt(CH3)Cl(C25H23N2P)], the N-benzyl-N-(diphenyl­phosphanylmeth­yl)pyridin-2-amine functions as a bidentate ligand with the pyridyl N atom and the phosphine P atom chelating the PtII ion, forming a six-membered metallocycle. The PtII atom adopts a square-planar coordination geometry with one methyl group and one chloride ligand bonding to the metal center in a cis relationship. C—H⋯π and C—H⋯Cl inter­actions help to consolidate the packing.

Chlorido(4,4′,4′′-tri-tert-butyl-2,2′:6′,2′′-terpyridine)platinum(II) chloride toluene monosolvate

In the title compound, [PtCl(C27H35N3)]Cl·C7H8, the PtII atom is coordinated in a pseudo-square-planar fashion by the N atoms of a 4,4′,4′′-tri-tert-butyl-2,2′:6′,2′′-terpyridine (tbtrpy) ligand and a Cl atom. The Pt—N distance of the N atom on the central pyridine is 1.941 (4) Å, while the peripheral N atoms have Pt—N distances of 2.015 (4) and 2.013 (4) Å. The Pt—Cl bond distance is 2.3070 (10) Å. The cations pack as dimers in a head-to-tail orientation with an inter­molecular Pt⋯Pt distance of 3.2774 (3) Å and Pt⋯N distances of 3.599 (4), 3.791 (4) and 4.115 (4) Å. The solvent mol­ecule is disordered and occupies two positions with a ratio of 0.553 (6):0.447 (6).