László Jánosi

Crystal structure and reactivity of mononuclear cationic palladium(II) and platinum(II) triphos complexes with phenyltin(IV) anions. The formation of polynuclear platinum-triphos ionic and covalent complexes

The ionic complexes [M(triphos)Cl]X [M = Pd, X = Cl (1), SnCl3 (1a), SnPh2Cl3 (1c); M = Pt, X = Cl (3), SnCl3 (3a), SnPh2Cl3 (3c)], [M(triphos)Cl](2)X [X = SnPh2Cl4, M = Pd (1b), Pt (3b); X = PtCl4, M = Pt (3d)] and [M(triphos)(2)]X-2 [X = SnPh2Cl3, M = Pd (2), Pt (4)] where triphos = bis(2-diphenylphosphinoethyl)phenylphosphine, were synthesised and characterised by microanalysis, mass spectrometry, IR, Sn-119 Mossbauer, NMR (P-31, Pt-195 and Sn-119) spectroscopies and conductivity measurements. The X-ray crystal structures of compounds 1b, 3b and 3c, where tetrachlorodiphenylstannate(IV) and trichlorodiphenylstannate(IV) act as counterions stabilising cationic metal complexes, are reported. These compounds contain the cation [M(triphos)Cl](4) with distorted square-planar geometry at palladium or platinum, triphos acting as a tridentate chelating ligand. The anions [SnPh2Cl4](2-) (1b, 3b) and [SnPh2Cl3](-) (3c) have trans-octahedral and distorted trigonal-bipyramidal environments for the metal, respectively. Although the dinegatively charged [SnPh2Cl4](2-) is counteracted by the presence of two singularly positively charged [M(triphos)Cl](+) species, interanion contacts via hydrogen bonds were found for Ib and 3b but were absent for compound 3c. The crystalline solids [M(triphos)(2)][SnPh2Cl3](2) [M = Pd (2), Pt (4)] were formed via a chelate ring-opening reaction of [M(triphos)Cl](+) induced by triphos. The formation of heterometallic complexes by reaction of AgCl or Au(I) with the complex [Pt(triphos)(2)][SnPh2Cl3](2) (4), followed by P-31 NMR in solution, did not take place. The presence of dangling arm phosphine oxide groups, on oxidation of complex 4 with H2O2, was detected. Other ring-opening reactions were observed by P-31 NMR and conductivity measurements when solutions containing PtC1(2)(PhCN)(2) and triphos in a molar ratio 3:2 were refluxed C,H,. Besides [Pt(triphos)Cl](2)[PtCl4] (3d) and the ionic complex with a dinuclear anion, [Pt(triphos)Cl][Pt-2(triphos)Cl-5] (5). the covalent trinuclear complexes [{PtCl2(Ph2PCH2CH2)(2)PPh-P-1,P-2} (2)(P-3,P-3)PtCl2] (6a, 6b) were formed as minor products. These latter diastereomeric species become the dominant species upon heating, being thermodynamically controlled complexes. Mixtures of 3d, 5, 6a and 6b converted to complex [Pt(triphos)Cl]Cl (3) by addition of triphos, chelate ring-closure reactions of 6a, 6b and the complex anion 5 occurring. With an excess of triphos (Pt:triphos = 3:4 or higher ratio), broad peaks reflecting fast equilibria between ring-opened and ring-closed products were found

Platinum complexes of (R)-N,N-bis(2-(diphenylphosphino)ethyl)-1-phenyl-ethylamine: Their synthesis and characterisation

Abstract Both neutral and ionic platinum complexes of ( R )- N , N -bis(2-diphenylphosphinoethyl)-1-phenyl-ethylamine (PNP) were synthesised. In the reaction of PtCl 2 (PhCN) 2 and PNP cis -PtCl 2 (η 2 -P,P-PNP) ( 1 ) was formed coordinating PNP as a P,P-bidentate ligand. Diastereotopic phosphorus atoms were observed in 31 P NMR upon addition of SnCl 2 to the parent complex ( 1 ) due to the formation of [PtCl(PNP)][SnCl 3 ] ( 2a ). The formation of similar complex cations, [PtX(PNP)] + (where X=I ( 4 ), CN ( 5 )) containing PNP as a terdentate ligand was also observed when KI and KCN was added in the presence of SnCl 2 , which formed trichlorostannate counterion. The addition of PPh 3 to 1 resulted in the partial formation of [Pt(PPh 3 )(PNP)] 2+ ( 3 ), which could be accomplished upon addition of SnCl 2 . The catalytic activity of the platinum–PNP system in the hydroformylation of styrene is low.

Synthesis and NMR investigation of Pt(CN)2(diphosphine) and [Pt(CN)(triphosphine)]Cl complexes

Abstract Pt(CN) 2 (Ph 2 P(CH 2 ) n PPh 2 ) ( n =2,3,4) and Pt(CN) 2 (P 1 P 2 ) (P 1 P 2 =1-diphenylphosphino-2,1′-[(1-diphenylphosphino)-1,3-propanediyl]-ferrocene, 1-diphenylphosphino-2,1′-[(1-dicyclohexylphosphino)-1,3-propanediyl]-ferrocene) were synthesised by reacting potassium cyanide and the corresponding PtCl 2 (diphosphine) complexes. PtCl(CN)(diphosphine) complexes were identified as minor products when KCN/PtCl 2 (diphosphine) molar ratio was kept below 2. The use of KCN in excess resulted in the formation of K 2 Pt(CN) 4 . [Pt(CN)({Ph 2 P(CH 2 ) 2 } 2 PPh)] + complex cation and Pt(CN) 2 )({Ph 2 P(CH 2 ) 2 } 2 PPh) five-coordinate covalent complex of fluxional behaviour were obtained at KCN/Pt ratio of 1 and 2, respectively. The platinum–cyano complexes were characterised by NMR spectroscopy. The direct PtCN bond was proved by 1 J ( 195 Pt, 31 P), 2 J ( 31 P, 13 C) coupling constants by using sodium cyanide- 13 C for ligand exchange reactions.