Diamidato-bis(diphenylphosphino) platinum(II) complexes: Synthesis, characterization, and reactivity in the presence of acid

A Phosphine Functionalized β-Diketimine Ligand for the Synthesis of Manifold Metal Complexes

A bis(diphenyl)-phosphine functionalized β-diketimine (PNac-H) was synthesized as a flexible ligand for transition metal complexes. The newly designed ligand features symmetrically placed phosphine moieties around a β-diketimine unit, forming a PNNP-type pocket. Due to the hard and soft donor atoms (N vs. P) the ligand can stabilize various coordination polyhedra. A complete series ranging from coordination numbers 2 to 6 was realized. Linear, trigonal planar, square planar, tetrahedral, square pyramidal, and octahedral coordination arrangements containing the PNac-ligand around the metal center were observed by using suitable metal sources. Hereby, PNac-H or its anion PNac- acts as mono-, bi- and tetradendate ligand. Such a broad flexibility is unusual for a rigid tetradentate system. The structural motifs were realized by treatment of PNac-H with a series of late transition metal precursors, for example, silver, gold, nickel, copper, platinum, and rhodium. The new complexes have been fully characterized by single crystal X-ray diffraction, NMR, IR, UV/Vis spectroscopy, mass spectrometry as well as elemental analysis. Additionally, selected complexes were investigated regarding their photophysical properties. Thus, PNac-H proved to be an ideal ligand platform for the selective coordination and stabilization of various metal ions in diverse polyhedra and oxidation states.

Organodiphosphines in Pt{η2-P(X)nP}Cl2 (n = 9–15, 17, 18) derivatives – Structural aspects

This review covers over 20 monomeric platinum complexes of Pt{η2-P(X)nP}Cl2 (n = 9–15, 17, 19) type. The chelating P,P-donor ligands create wide varieties of the metallocyclic rings: 12-membered (PC9P, PC3NCNC3P), 13-membered (PC3NC2NC3P), 14-membered (PC11P, PO(SiO)5P, PC2OC2OC2OC2P), 15-membered (PC12P), 16-membered (PCOC9OCP), 17-membered (P(C2O)4C2P), 18-membered (PC2OC9OC2P, PC4NC2NC2NC4P), 20-membered (P(C2O)5C2P), and 21-membered (POC2NC10NC2OP). For these complexes the most common is a predominantly cis-arranged with 17 examples and only four examples with trans-configuration. The total mean values of Pt–L bond distances in the complexes with cis- versus trans-configuration are: 2.252 Å (P trans to Cl), 2.355 Å (Cl trans to P) vs 2.288 Å (P trans to P), and 2.304 Å (Cl trans to Cl). There are examples which exist in cis- and trans-isomeric forms and distortion isomers. A brief survey on the structural data of almost 180 examples of Pt{η2-P(X)nP}Cl2 (n = 1–8) type complexes is added and discussed.

Stereochemistry of Pt(η2-P2L)Cl2 derivatives

The coordination chemistry of platinum (Pt) covers a huge field as shown by a recent survey covering the crystallographic and structural data of almost 200 monomeric examples of the Pt(η2-P2L)Cl2type. About 20% of these complexes exist as isomers and are discussed in this review. Included are distortion (64%),cis-trans(20%), and ligand (16%) isomers. These are discussed in terms of the metallocyclic rings, and coordinations are drawn between donor atoms, bond lengths, and interbond angles, with attention to anytrans-influence. Distortion isomers, differing only by the degree of distortion in Pt-L and L-Pt-L angles, are the most numerous. In this series of distortion and ligand isomers, the square-planar configuration about the Pt(II) atom has onlycis-configuration. The total mean values of Pt-L bond distances (cis- vs.trans-configuration) are 2.228 Å (P) and 2.353 Å (Cl) vs. 2.312 (P) and 2.302 Å (Cl).

Chiral amino-phosphine and amido-phosphine complexes of Ir and Mg. Catalytic applications in olefin hydroamination

The reactions of rac- and (S,S)-trans-9,10-dihydro-9,10-ethanoanthracene-11,12-diamine (ANDEN) with PClPh2 in the presence of NEt3 yield the chiral amino-phosphine ligands rac-6 and (S,S)-6, respectively, on multi-gram scales. Both forms of 6 react quantitatively with MgPh2 to afford the C2-symmetric, N-bound Mg amidophosphine complexes rac-7 and (S,S)-7. The former crystallizes as a racemic conglomerate, which is a rare occurrence. Mixing (S,S)- or rac-6 with [IrCl(COE)2]2 leads in both cases to the homochiral dinuclear chloro-bridged P-ligated aminophosphine iridium complexes (S,S,S,S)-9 and rac-9 in excellent yields. X-ray quality single crystals only grow as the racemic compound (or 'true racemate') rac-9 thanks to its lowered solubility. In the coordinating solvent CH3CN, rac-9 transforms in high yield into mononuclear Ir-complex rac-10. The crystal structures of compounds rac-6, (S,S)-7, rac-9, and rac-10 reveal the ambidentate nature of the P-N function: amide-coordination in the Mg-complex (S,S)-7 and P-chelation of the softer Ir(i) centres in complexes rac-9 and rac-10. Furthermore, the crystal structures show flexible, symmetry lowering seven-membered P-chelate rings in the Ir complexes and a surprising amount of deformation within the ANDEN backbone. The simulation of this deformation by DFT and SCF calculations indicates low energy barriers. (S,S)-7 and (S,S,S,S)-9 catalyze the intra- and intermolecular hydroamination of alkenes, respectively: 5 mol% of (S,S)-7 affords 2-methyl-4,4'-diphenylcyclopentyl amine quantitatively (7% ee), and 2.5 mol% of (S,S,S,S)-9 in the presence of 5.0 mol% co-catalyst (LDA, PhLi, or MgPh2) gives exo-(2-arylamino)bornanes in up to 68% yield and up to 16% ee.