Monoarylplatinum(II) Complexes with a 2-Phenylpyridyl Ligand and Coordinated Solvent, [Pt(Ar)(Phpy)(solv)] (Phpy = 2-phenylpyridyl; solv = NCCH₃, dmso). Preparation from [Pt(Ar)₂(solv)₂], Structures, and Chemical Properties

Abstract

Diarylplatinum(II) complexes, [Pt(Ar)2(dmso)2] (Ar = C6H3Me2-3,5 (1a), C6H3(CF3)2-3,5 (1b), Ph (1c); dmso = dimethyl sulfoxide) and [Pt{C6H3(CF3)2-3,5}2(NCCH3)2] (2b), were prepared and fully characterized. Heating mixtures of 2-phenylpyridine (PhpyH) with the complexes in solution at 50 °C caused coordination of PhpyH and its cyclometalation accompanied by elimination of arene to produce monoarylplatinum(II) complexes with a solvent ligand, [Pt(Ar)(Phpy)(dmso)] (Ar = C6H3Me2-3,5 (3a), C6H3(CF3)2-3,5 (3b), Ph (3c)) and [Pt{C6H3(CF3)2-3,5}(Phpy)(NCCH3)] (4b). The rate of the reactions decreased in the order 1a > 1c > 2b > 1b. Crystal structures of 3a,c and 1H NMR spectra of the complexes showed that the aryl ligand and phenyl group of the Phpy ligand occupied cis positions. A diarylplatinum complex with a monodentate phenylpyridyl ligand, [Pt(C6H3Me2-3,5)2(CF3PhpyH)(dmso)] (5), was isolated and characterized using X-ray crystallography. The neutral arylplatinum(II) complex 4b underwent exchange of the acetonitrile ligand more easily than the cationic complex, [Pt{C6H3(CF3)2-3,5}(bpy)(NCCH3)]+, because of the C-bonded phenyl group of the Phpy ligand had a greater trans effect than the N-bonded pyridyl group of bpy. Oxidative addition of I2 to 3a,b and 4b readily gave Pt(IV) dimeric complexes with bridging iodo ligands, [(Pt(Ar)(Phpy)I)2(μ-I)2] (Ar = C6H3Me2-3,5 (7a), C6H3(CF3)2-3,5 (7b)). The dimeric structure of 7b was confirmed using X-ray crystallography.

1H, 13C, 15N and 195Pt NMR studies of Au(III) and Pt(II) chloride organometallics with 2‐phenylpyridine

“…* )(DMSO) (3,5-dimethylphenyl)] and [Pt(2ppy * )(DMSO)(3,5-di(trifluoromethyl)phenyl)]; [11] trans(N,N)-[Pt(2ppy * )(4-methoxy-py)Cl] and trans(N,N)-[Pt(2ppy * )(2-(2-thienyl)-py)Cl]; [9] [Pt(2ppy [27] [Pt(2ppy * )(2,3-bis(2-pyridyl)pyrazine)] + and [Pt(2ppy * )(6,7-dimethyl-2,3-bis(2-pyridyl) quinoxaline)] + ; [30] [12] [Pt(2ppy * )(5-nitro-8-oxyquinolinate)]; [31] cis-[Pt(2ppy * ) 2 ]. [13,32] However, the respective 1 H and 13 C signals usually remained unassigned or were assigned inconsistently by various authors.…”

“…[5,6] Some other X-ray structures were reported for the related Au(III) and Pt(II) cyclometallated compounds with various auxiliary ligands, e.g. [Au(2ppy * [3] trans(S,N)-[Au(2ppy * )(SCN)(NCS)] -ILETOI; [7] trans(C,N)-[Au(2ppy * )(CH 2 COCH 3 )Cl] -BIGRAL and trans(C,N)-[Au(2ppy * ) (CH 2 COCH 3 )(ONO 2 )] -BIGREP; [8] [9] [Pt(2ppy * )(NH 2 CH 2 CH 2 NH 2 )]Cl -ZUDGIO; [4] trans(C,N)-[Pt(2ppy * ) (DMSO)(CH 3 )] -BEZPEC; [10] trans(C,N)-[Pt(2ppy * )(DMSO)(C 6 H 5 )] -TICSII and trans(C,N)-[Pt(2ppy * )(DMSO) (3,5-dimethylphenyl)] -TICSEE; [11] trans(N,N)-[Pt(2ppy * )(8-oxyquinolinate)] -WESQUH; [12] cis-[Pt(2ppy * ) 2 ] -CULWUB; [13] K[Pt(2ppy * )(CN) 2 ]· 2(CH 3 COC H 3 ). [14] These or similar compounds were also investigated by 1 H and/or 13 C NMR methods: [Au(2ppy * )Cl 2 ]; [1,3,15] [Au(2ppy * ) (OCOCH 3 [3] [Au(2ppy * )(SC H 2 CH 2 S)] and [Au(2ppy * )(SCH 2 CH 2 NH 2 )] + ; [15] trans(S,N)-[Au(2p py * )(SCN)(NCS)]; [7] trans(C,N)-[Au(2ppy * )(CH 2 COCH 3 )(ONO 2 )]; [8] [Au(2ppy * )(NH 2 CH 2 CH 2 NH 2 )] 2+ and [Au(2ppy * )(2,2 -bipyridine )] 2+ ; [16] trans(N,N)-[Pt(2ppy * )(2ppy)Cl]; [2,5,9,17 -19] [Pt(2ppy * )(2ppy) X] (X = Br, I, SCN, ONO 2 , NO 2 ); [19] [Pt(2ppy * )Cl 2 ] − ; [2] [Pt(2ppy * ) (CO)Cl]; [5,17,20] [Pt(2ppy * )(NH 3 )Cl]; [17] trans(S,N)-[Pt(2ppy * )(DMSO) Cl]; [9,17,21] [Pt(2ppy * )(P(C 6 H 5 ) 3 )Cl] and [Pt(2ppy * )(py)Cl]; [22] [Pt(2p py * )(CN) 2 ] − ; [14,…”

Diarylplatinum(II) Compounds as Versatile Metallating Agents in the Synthesis of Cyclometallated Platinum Compounds with N-Donor Ligands

“…Further examples of cyclometallation at diarylplatinum(II) compounds [45]. Evidence from the fact that cis configuration of the platinum precursor is not required comes from the fact that double cyclometallation of 3,6-bis(2-thienyl)-1,2,4,5-tetrazine has been achieved from the precursor trans-[Pt (2,4,6-Me 3 C 6 H 2 ) 2 (dmso) 2 ] in a reaction leading to a dinuclear platinum(II) compound [55].…”

“…Complexes having more electron-donating substituents at the aryl group undergo faster cyclometallation, however, as shown in Scheme 4, compounds [Pt(Ar)(PhPy)(dmso)] containing a cyclometallated phenylpyridine could be obtained from compounds [PtAr 2 (dmso)] even when the aryl groups contain electronwithdrawing substituents such as Ar = 3,5-(CF 3 ) 2 C 6 H 3 [45]. Scheme 3.…”

“…In these reactions, the labile dimethylsulfoxide or dimethylsulfide ligands can be readily replaced by N-donor ligands, and the intramolecular C-H bond activation proceeds with elimination of benzene. Although, diphenylplatinum(II) derivatives are reported to be less prone to cyclometallation than the corresponding dimethyl derivatives, metallation of 2-phenylpyridines, benzo[h]quinoline or imines containing biphenyl, pyridyl or pyrimidine fragments has been achieved [44][45][46][47][48]. In addition, "rollover" cyclometallation of substituted bipyridines, including multiple C-H bond activation, and functionalized N-(2'-pyridyl)-7-azaindolyl ligands has been achieved using diarylplatinum precursors (see Scheme 2) [31][32][33]49,50].…”