Platinum(II) and Palladium(II) Halides and Pseudohalides with the Ligand Tri(1-cyclohepta-2, 4, 6-trienyl)phosphane : X-Ray Structural Analysis of [P(C₇H₇)₂(η²-C₇H₇)]PtI₂

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Herberhold, Max ; Schmalz, Thomas ; Milius, Wolfgang ; Wrackmeyer, Bernd:
Platinum(II) and Palladium(II) Halides and Pseudohalides with the Ligand Tri(1-cyclohepta-2, 4, 6-trienyl)phosphane : X-Ray Structural Analysis of [P(C₇H₇)₂(η²-C₇H₇)]PtI₂.
In: Zeitschrift für anorganische und allgemeine Chemie. Bd. 628 (2002) Heft 2 . - S. 437-445.
ISSN 1521-3749
DOI: https://doi.org/10.1002/1521-3749(200202)628:2<437::AID-ZAAC437>3.0.CO;2-Z

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Abstract

Tri(1-cyclohepta-2, 4, 6-trienyl)phosphane, P(C7H7)3 (1) (P when coordinated to a metal) stabilizes platinum(II) (2) and palladium(II) dihalides (3) as PMX2 with X = Cl (a), Br (b) and I (c). The phosphane coordinates to the metal as a chelate ligand via both phosphorus and the central η2-C=C bond of one of the cyclohepta-2, 4, 6-trienyl rings. The complexes were prepared by various routes, mainly by the reaction of (cod)MCl2 (cod = cycloocta-1, 5-diene) with 1 to give the chlorides 2a and 3a, which then could be converted into the bromides 2b, 3b or the iodides 2c, 3c by reaction with NaBr or NaI, respectively. The molecular structure of 2c was determined by X-ray analysis. Treatment of 2a and 3a with sodium or potassium salts of several pseudohalides afforded the complexes PMX2 2d (NCO/NCO), 2e1 (NCS/SCN), 2e1'(SCN/NCS), 2f2 (SeCN/SeCN), 3f1(NCSe/SeCN), 2g and 3g (X = N3). Attempts failed to synthesize the cyanides 2h and 3h by the same route. By using an excess of trimethylsilyl cyanide in the reaction with 2a in THF solution, the complex trans-{(C7H7)3P2Pt(CN)2} (4h) was obtained instead of 2h. The analogous complexes trans-{(C7H7)3P2MX2} with M = Pt (4) and Pd (5) for X = Cl (a), Br (b), I (c) could be prepared from the reaction of the corresponding tetrahalogenometallates and 1 (in the case of 5c from PdI2 and 1). In contrast to 4h, the complexes 4a-c and 5a-c were found to be labile in solution with respect to partial loss of the phosphane 1 and rearrangement into 2a-c and 3a-c, respectively. All compounds were characterized by IR spectroscopy and by multinuclear magnetic resonance spectroscopy (1H, 13C, 31P, 77Se and 195Pt NMR). The ligand P in 2 and 3 is fluxional with regard to coordination of the C7H7 rings to the metal.