Three-Fold Intramolecular Ring-Closing Metatheses Involving Square-Planar Platinum Complexes with cis-Phosphorus Donor Ligands: Syntheses, Structures, and Properties of Parachute-like Complexes

Abstract

Reactions of the phosphite and phosphine complexes cis-PtCl 2((PX(CH2)mCH=CH2)3)2 (X/m = O/3, O/4, O/5, -/5, -/6) with Grubbs' catalyst, followed by hydrogenations, yield cis-PtCl2(P(X(CH2)(2m+2)X)3P) (6-40%). Crystal structures establish parachute-like motifs in which one X(CH2)(2 m+2)X bridge lies roughly in the platinum coordination plane, and the others lie above and below.

Dreifach‐verbrückte Diphosphane mit von innen nach außen invertierender Konfiguration

“…Diese Umlagerung verläuft über eine der (CH 2 ) 14 [3] In diesem Zusammenhang sollte nicht unerwähnt bleiben, dass auch cis-1 (Schema 1) über eine unabhängige Sythesesequenz erhalten werden kann. [15] Der idealisierte 908-Winkel zwischen den am Platinzentrum gebundenen Elektronenpaaren der beiden Phosphordonoratome demonstriert eindrucksvoll die immanente Flexibilität des Diphosphanliganden 2. [16] Um unsere mechanistische Modellvorstellung zu untermauern, wäre eine authentische Probe von in,out-2 von herausragender Bedeutung.…”

Dibridgehead Diphosphines that Turn Themselves Inside Out

“…[3] In this context, it is relevant that cis-1 (Scheme 1) can be independently prepared. [15] The idealized 908 angle between the lone pairs of electrons on the phosphorus atoms demonstrates the inherent flexibility of 2. [16] This mechanistic model would be strengthened by a sample of in,out-2.…”

Syntheses of gyroscope-like molecules via three-fold ring closing metatheses of bis(phosphine) complexes trans-LyM(P((CH2)nCHCH2)3)2, and extensions to bis(phosphite) complexes trans-Fe(CO)3(P(O(CH2)nCHCH2)3)2

“…However, the phosphite ligands 26a-f have been introduced into other metal fragments, from which crystalline polycyclized metathesis products -although not of the types in Fig. 8 -can be derived [31]. These will be reported in future publications.…”

“…Surprisingly, only the former reaction mode is observed. In the case of 8d, an authentic sample was synthesized, but none could be detected by 31 P NMR in the crude product. We have no explanation at present for this selectivity, or the preference for 2 in Scheme 1.…”