Syntheses, structures and solution behaviour of cyclotriphosphato complexes of Pd(ii), Pt(ii) and Pt(iv)

Dalton Transactions Pub Date: 2003-05-28 DOI: 10.1039/B301223A

Abstract

The cyclotriphosphate ion (P3O93?) as a PPN [PPN = (Ph3P)2N+] salt reacted in CH2Cl2 at room temperature with the cationic solvated complexes of Pd(II) and Pt(II), [M(phosphine)2(Me2CO)2]2+ [M = Pd, Pt; phosphine = PPh3, PMePh2, 1/2 Ph2P(CH2)2PPh2 (dppe), 1/2 Ph2P(CH2)4PPh2 (dppb)], to give the anionic P3O9 complexes (PPN)[Pd(P3O9)(PPh3)2] (1), (PPN)[Pd(P3O9)(PMePh2)2] (2), (PPN)[Pt(P3O9)(PPh3)2] (3), (PPN)[Pt(P3O9)(PMePh2)2] (4), (PPN)[Pt(P3O9)(dppe)] (5) and (PPN)[Pt(P3O9)(dppb)] (6). Crystallographic studies revealed that the P3O9 ligand in complexes 1–4 and 6 adopts a normal chair conformation and behaves as a pseudo-tridentate ligand with two normal M–O bonds and an additional weak M?O interaction. In 1 and 3, the terminal P3O9 oxygen atom weakly bound to the metal centre forms relatively strong intramolecular CH?O hydrogen bonds with the phosphine ligands. In contrast, the P3O9 ligand in 5 is bidentate and takes a pseudo-boat conformation. Complexes 1–6 are fluxional in solution and exhibit only one singlet due to the P3O9 ligand in the 31P–{1H} NMR spectra at room temperature; the signals of complexes 4–6 split into two at ?40 to ?70 °C. The activation parameters for the fluxional behaviour of 6 were determined by the line shape analysis of the variable temperature 31P–{1H} NMR spectra. The Pt(IV) complex (PPN)2[PtMe3(P3O9)] (7) was also synthesised and structurally characterised.

Graphical abstract: Syntheses, structures and solution behaviour of cyclotriphosphato complexes of Pd(ii), Pt(ii) and Pt(iv)
Recommended Literature