Niederkoordinierte Phosphor‐Verbindungen. 42. Trennung und röntgenographische Strukturbestimmung der E,Z‐Isomeren des 2,4,6‐Tri(tert.butyl)phenyl‐phenylmethylenphosphans

Abstract

Durch fraktionierte Kristallisation und HPLC können die bei Phosphaalkenen auftretenden E,Z‐Isomere getrennt werden. Die E‐ und die Z‐Form des Phosphaalkens 2a werden röntgenographisch untersucht.

Role of the aromatic bridge on radical ions formation during reduction of diphosphaalkenes

“…As reported in ESI,z for both compounds, the two Mes*PQC(H)-C 6 H 5 moieties exhibit the geometrical characteristics reported for this type of phosphaalkene: 15 the CPC(H)C groups are practically planar, and are oriented perpendicular to the benzene ring of Mes* (Ph3a or Ph3b hereafter, see The main differences between the conformations of 1 and 2 result from the steric interactions between the phenyl rings Ph2a and Ph2b: the distance between the centroids of these two phenyl rings is equal to 5.30 Å in 1 and only 3.66 Å in 2. In 1 the constraints are, of course, less pronounced than in the naphthalene containing system: while the x interplane angles (Ph1a, Ph2a) and (Ph1b, Ph2b) are equal to 52.61 and 47.…”

“…Compound 1 crystallizes in the triclinic system, space group P % 1; compound 2 crystallizes in the monoclinic system, space group P2 1 /n. As reported in ESI,z for both compounds, the two Mes*PQC(H)-C 6 H 5 moieties exhibit the geometrical characteristics reported for this type of phosphaalkene: 15 the CPC(H)C groups are practically planar, and are oriented perpendicular to the benzene ring of Mes* (Ph3a or Ph3b hereafter, see Fig. 1), the PC(H)C planes make an angle of B301 Scheme 1 with the adjacent phenyl rings (Ph2a or Ph2b hereafter, see Fig.…”

Synthesis of the first metal-free phosphanylphosphonate and its use in the “phospha–Wittig–Horner” reaction

“…The solid state structure shows the Z relationship between the Mes* group and the naphthyl substituent, and is one of few crystal structures of uncoordinated acyclic Zphosphaalkenes (of the type ArP=C(H)R) in the literature. 35,[49][50][51][52][53][54][55][56] As seen in Figure 4, H C3 is located above the Mes* group and is therefore expected to be highly shielded due to the strong anisotropic effect induced by this ring. The characteristic upfield signal (doublet of doublets, 5.74 ppm) in the 1 H NMR spectrum is a clear-cut proof supporting this claim.…”

Synthesis and characterisation of the platinum complexes [PtCl(CClPAr)(PPh3)2] and [PtCl(CClPAr′)(PPh3)2] as potential intermediates in the preparation of phosphaalkynes

“…The atoms Pt, P(2), P(3), Cl(1) and C(10) are nearly coplanar. The C(10)-P(1) distances (1.688(2) Å in 5a, 1.688(4) Å in 6a) are the same within experimental error as those of the C@P bonds in trans-[PtCl(ClC@PMes*)(PEt 3 ) 2 ] (1.678(5) Å ) [30], Ph(Me 3 Si)C@PMes* (1.676(6) Å ) [32] and Ph 2 C@PMes (1.692(3) Å ) [32]. Three short contacts between the fluorine atoms of the o-CF 3 groups and the phosphorus atom were found in both structures: P(1)Á Á ÁF(11) 3.039(2), P(1)Á Á ÁF(12) 3.159(2), P(1)Á Á ÁF(17) 2.911(1) Å in 5a, 3.088(3), 3.126(3) and 2.893(3) Å for the corresponding distances in 6a.…”