220528-51-8Relevant academic research and scientific papers
Influence on reactivity of chloro ligand substitution in mononuclear cationic Pd(II) and Pt(II) triphos complexes: X-ray structure of the nitrate derivatives
Fernández, Damián,Sevillano, Paloma,García-Seijo,Castieiras, Alfonso,Jánosi, László,Berente, Zoltán,Kollár, László,García-Fernández
, p. 40 - 52 (2008/10/08)
The substitution of chloro ligand in [M(triphos)Cl]Cl complexes [M = Pd (1), Pt (2); triphos = Ph2PC2H4P(Ph)C2H4 PPh2] by reaction with 1 equiv. of KX resulted in the formation of the ionic complexes [M(triphos)X]Cl [X = I, M = Pd (3), Pt (4); X = CN, M = Pd (5), Pt (6)]. Methanolic solutions of silver nitrate in excess displace the chloro ligand and counterion of 1 and 2, giving rise to the formation of the crystalline complexes [M(triphos)(ONO2)](NO3) [M = Pd (7), Pt (8)] suitable for X-ray diffraction studies. The complexes show a distorted square-planar environment around the metal, there being three coordination sites occupied by phosphorus atoms from the triphos and the fourth by the oxygen atom from a nitrate acting as monodentate ligand. A second NO3- is acting as counterion with D3h symmetry. The use of a high excess of SnCl2 in the presence of 1 equiv. of PPh3 enabled the formation of complexes [M(triphos)(PPh3)](SnCl3)2 [M = Pd (9), Pt (10)]. These complexes, in addition to [M(triphos)X]X [X = Br, M = Pd (1a), Pt (2a); X = I, M = Pd (1b), Pt (2b)], were synthesised and all Pt(II) complexes characterised by microanalysis. Mass spectrometry, IR spectroscopy, NMR spectroscopy and conductivity measurements were also used for characterisation. The structure and reactivity studies in solution were carried out by 31P{1H} NMR. The trends in chemical shifts δ (P) and 1J(195Pt,31P) coupling constants were used to establish a sequence in the X ligand exchange reactions. While [Pd(triphos)I]I (1b) undergoes a ring-opening reaction by titration with AuI, the analogous Pt(II) complex (2b) does not react. The formation of new five-coordinate Pd(II) and Pt(II) complexes was observed by titration of 5-8 with potassium cyanide.
Chelate ring-opening of Pd(II) triphos complexes: Ligand exchange, selective phosphine oxidation, and X-ray crystal structure of [Pd(Ph2P(CH2)2PPh(CH2) 2P(O)Ph2)2Br]Br
Sevillano, Paloma,Habtemariam, Abraha,Castineiras, Alfonso,Esther Garcia,Sadler, Peter J.
, p. 383 - 389 (2008/10/08)
31P NMR studies show that chelate ring-opening of [Pd(triphos)Cl]+ , 4, (triphos = Ph2P(CH2)2PPh(CH2) 2PPh2) can be achieved in solution by reaction with excess of triphos with the formation of [Pd(Ph2P(CH2)2PPh(CH2)2PPh 2-P,P)2]2+. In the X-ray crystal structure, [Pd(triphos)Br]Br, 1 has a distorted square-planar geometry, and the oxidation of 1 with H2O2 gives rise to [Pd(Ph2P(CH2)2PPh(CH2) 2P(O)Ph2-P,P)2]2+, 2, which contains two bidentate ligands. The presence of two dangling arm phosphine oxide groups was confirmed by X-ray crystallography for the related complex [Pd(Ph2P(CH2)2PPh(CH2) 2P(O)Ph2-P,P)2Br]Br, 3, which contained square-pyramidal five-coordinated Pd(II).
