Ligand isomerism in Pt(II) complexes – structural aspects

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Milan Melník ◽  
Peter Mikuš
Keyword(s):  
Mixed Ligand ◽  
Bidentate Ligands ◽  
Trans Isomers ◽  
Mean Values ◽  
Bite Angle ◽  
Coordination Spheres ◽  
Structural Aspects

Abstract This review has focused on ligand isomers in Pt(II) complexes. There are a variety of inner coordination spheres about the platinum(II) atom (PtN4, PtN2Cl2, PtP2Cl2, PtPNC2, PtPNCl2, PtP2CBr, PtP2CS), build up by mono- and bidentate ligands. The bidentate ligands create a variety of metallocyclic rings. The L–Pt–L bite angle (mean values) open in the sequence: 73.1° (PNP) < 78.7° (NC2C) < 80.4° (NC2N) < 86.4° (PC2P) < 86.7° (PNNP) < 93.0° (CC3S). There are three types of isomers: ligand, mixed – (ligand + distortion), and mixed – (ligand + cis-trans), isomers, which are rarity.

Distortion isomers of cis-PtP2X2 and cis-PtP2XY derivatives – structural aspects

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Milan Melník ◽  
Peter Mikuš
Keyword(s):  
Crystal Packing ◽  
Structural Parameters ◽  
Coordination Complexes ◽  
Mean Value ◽  
Covalent Radius ◽  
Mean Values ◽  
Trans Influence ◽  
Coordination Spheres ◽  
The Mean ◽  
Structural Aspects

AbstractIn this review, the structural parameters of distortion isomers of cis-monomeric Pt(II) coordination complexes with inner coordination spheres: Pt(PL)2X2 (X = OL, NL, SL, Br, I); Pt(PL)2(η2-X2L) (X = O2L, N2L, S2L, OSL, NSL, NSeL); Pt(η2-P2L)X2 (X = Br, I); Pt(η2-P2L)(η2-X2L) (X = O2L, OSL, NSL); Pt(η2-P2L)(NL)(Cl) and Pt(PL)(η2-P,SiL)(H) are analyzed. None of the distortion isomers with cis-configuration has a trans-partner. The distortion isomers differ mostly by the degree of distortion in the Pt-L and L-Pt-L angles. Some of the isomers also differ by crystal packing. The total mean values of Pt-P (monodentate) and Pt-P (bidentate) bond distances are 2.279 Å and 2.244 Å, respectively. The mean value of Pt-P (monodentate) (trans to H¯) of 2.320 Å is the highest one because of higher trans-influence of H¯ over PP3. The total mean values of Pt-X (trans to P) elongate quite well with the covalent radius of the X in the sequence: 1.57 Å (X = H) < 2.062 Å (O2L) < 2.095 Å (OL) < 2.108 Å (NL) < 2.154 Å (N2L) < 2.329 Å (Cl) < 2.342 Å (S2L) < 2.347 Å (SL) < 2.480 Å (Br) < 2.616 Å (I).

Organophosphines in organoplatinum complexes: structural aspects of trans-PtP2C2 derivatives

2017 ◽  
Vol 37 (1) ◽  
pp. 1-10
Author(s):  
Milan Melník ◽  
Peter Mikuš
Keyword(s):  
Coordination Sphere ◽  
Coordination Mode ◽  
Structural Parameters ◽  
Donor Ligands ◽  
Chelating Ligands ◽  
Mean Values ◽  
Structural Aspects

AbstractThis review summarized and analyzed the structural parameters of 174 monomeric organoplatinum complexes with an inner coordination sphere of trans-PtP2C2. These complexes crystallized in four crystal systems: hexagonal (x2), orthorhombic (x13), triclinic (x76), and monoclinic (x84). These complexes, on the basis of the coordination mode of the respective donor ligands, can be divided into the seven sub-groups: Pt(PL)2(CL)2, Pt(PL)2(η2-C2L), Pt(η2-P2L)(CL)2, Pt(PL)(η2-P,CL)(CL), Pt(η2-P,CL)2, Pt(η3-P,C,PL)(CL), and Pt(η3-C,P,CL)(PL). The chelating ligands create 4-, 5-, 6-, 16-, 17-, 18-, and 19-membered rings. The total mean values of Pt-L bond distances are 2.055 Å (C) and 2.300 Å (P). There are examples that exist in two isomeric forms and are examples of distortion isomerism. The structural parameters of trans-PtP2C2 are discussed with those of cis-PtP2C2 derivatives.

scholarly journals Crystal structure of diammonium bis[tris(oxamide dioxime-κ2 N,N′)nickel(II)] bis[tris(oxalato-κ2 O,O′)chromate(III)] 6.76-hydrate

2020 ◽  
Vol 76 (11) ◽  
pp. 1732-1736
Author(s):  
Yves Alain Mbiangué ◽  
Alfred Bijvédé ◽  
Patrice Kenfack Tsobnang ◽  
Emmanuel Wenger ◽  
Claude Lecomte
Keyword(s):  
Hydrogen Bonds ◽  
Water Molecules ◽  
Asymmetric Unit ◽  
Bidentate Ligands ◽  
Distorted Octahedral Coordination ◽  
Distorted Octahedral ◽  
Medium Strength ◽  
Anionic Complexes ◽  
Coordination Spheres ◽  
Charge Balancing

The asymmetric unit of the title compound, (NH4)2[Ni(C2H6N4O2)3]2[Cr(C2O4)3]2·6.76H2O, comprises two NH4 + cations, two [Ni(C2H6N4O2)3]2+ cations and two [Cr(C2O4)3]3– anions, as well as eight water molecules of crystallization of which only one is fully occupied. In the cationic and anionic complexes, the central atoms (NiII and CrIII) are each surrounded by three bidentate ligands (N-chelating oxamide dioxime and O-chelating oxalate, respectively), resulting in distorted octahedral coordination spheres. In the crystal, O—H...O hydrogen bonds between the oxamide dioxime ligands as donor groups and the oxalate ligands as acceptor groups alternately connect the cationic and anionic complexes into infinite pillars extending parallel to [100]. Moreover, N—H...O hydrogen bonds between the same ligands connect neighboring pillars, thus delineating channels that accommodate the charge-balancing NH4 + cations as well as the water molecules of crystallization. Although the H atoms could not be localized for these two species, the corresponding N...O and O...O distances indicate hydrogen bonds of medium strength.

Mixed Ligand Derivatives of 1: 1 Th(IV)—DTPA Chelate with Some Hydroxy Acids(H)

1975 ◽  
Vol 30 (9-10) ◽  
pp. 751-754 ◽  
Author(s):  
O. P. Pachauri ◽  
J. P. Tandon
Keyword(s):  
Formation Constants ◽  
Bidentate Ligand ◽  
Mixed Ligand ◽  
Bidentate Ligands ◽  
Hydroxy Acids ◽  
Titration Curves ◽  
Hydroxy Quinoline ◽  
Derivatives Of ◽  
Sulphosalicylic Acid ◽  
Secondary Ligand

Studies of the interaction between 1:1 Th(IV)-DTPA chelate (where DTPA = diethylenetriaminepentaacetic acid) with certain bidentate ligands, such as salicylic acid (SA), 5-sulphosalicylic acid (SSA) and 8-hydroxy quinoline-5-sulphonic acid (HQSA) have been carried out potentiometrically. The nature of the titration curves indicates that the bidentate ligand is added stepwise to the initially formed metal diethylenetriaminepentaacetate. The formation constants (log KMAB) of the resulting 1:1:1 mixed ligand derivatives have been determined at 30 ± 1 °C and μ = 0.1 (KNO3). The order of stability in terms of the secondary ligand has been found to be SA > SSA > HQSA.

Darstellung und Schwingungsspektren von Fluoro-Chloro-Iridaten(IV) einschließlich der Stereoisomeren / Preparation and Vibrational Spectra of Fluoro-Chloro-Iridates(IV) Including Stereoisomers

1984 ◽  
Vol 39 (9) ◽  
pp. 1185-1192 ◽  
Author(s):  
D. Tensfeldt ◽  
W. Preetz
Keyword(s):  
Ion Exchange ◽  
Vibrational Spectra ◽  
Ion Exchange Chromatography ◽  
Exchange Chromatography ◽  
Mixed Ligand ◽  
Trans Isomers ◽  
Trans Effect ◽  
Diethylaminoethyl Cellulose ◽  
Stretching Vibration ◽  
Point Groups

The reaction of [IrCl6]2- with BrF3 generates the mixed complexes [IrFnCl6-n]2-, n = 1-5, of which the species with n = 2, 3, 4 are ds-configurated. Due to the stronger trans-effect of Cl as compared to F on treatment of [IrF5Cl]2- and cis-[IrF4Cl2]2- with SOCl2 the trans-isomers are formed stereospecifically. The pure fluoro-chloro-iridates(IV) are separated by ion exchange chromatography on diethylaminoethyl-cellulose. The vibrational spectra of the mixed ligand complexes are completely assigned according to point groups D4h, C4v, C3v, and C2v. The IrCl stretching vibration of [IrF5Cl]2- is split by the isotopes 35C1 and 37Cl, showing two well resolved sharp Raman lines at 361 and 355 cm-1.

Structural aspects of heterooligonuclear platinum clusters – distortion isomers

2019 ◽  
Vol 39 (1) ◽  
pp. 1-12
Author(s):  
Milan Melník ◽  
Peter Mikuš ◽  
Mária Bodnár Mikulová
Keyword(s):  
Metal Bond ◽  
Metal Atoms ◽  
Metal Metal ◽  
Platinum Clusters ◽  
Coordination Spheres ◽  
Independent Molecules ◽  
Structural Aspects

AbstractThis review covers 15 clusters of the compositions Pt3Re2, Pt2Os3, Pt3AgAu, Pt3Ir3, Pt2M4 (M=Ag or Pd), PtM5 [M=Ru (×2) or Os], Pt3Os4, Pt6Au2, Pt2Ru6, Pt3Ru6, Pt2Ru8, and PtAu9. Each of the cluster contains two crystallographically independent molecules that differ mostly by degree of distortion and are classical examples of distortion isomerism. Their structures are very complex. The inner coordination spheres about the metal atoms (Pt and M) are very complex as well. The clusters are rich in metal-metal bond distances with the shortest being 2.573 Å (Pt-Au), 2.615 (Pt-Pt), and 2.673 Å (Ru-Ru).

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