Selective Cleavage by Acids of One Metal–Carbon σ‐Bond of a Bis(ortho‐platinated) Triarylphosphane: A ³¹P NMR trans‐Influence Series Based on the Unit Pt(κ²‐C₆H₃‐5‐Me‐2‐PPh₂)(PPh₂‐4‐tol)

Abstract

Treatment of the bis(chelate) complex cis-[Pt(κ 2 -C 6 H 3 -5-Me-2-PPh 2 ) 2 ] (1) with strong acids causes selective cleavage of one of the metal-aryl bonds to give cis-[PtX(κ 2 -C 6 H 3 -5-Me-2-PPh 2 )(PPh 2 -4-tol)] [X = Cl (2), Br (3), I (4), ONO 2 (5) and OCOCF 3 (6)], from which a series of neutral and cationic derivatives can be derived by metathetical reactions. The complexes 2 and 6 rearrange spontaneously to the corresponding trans isomers, this reaction being promoted by CO. The J(Pt-P) values for the phosphorus atom of the four-membered ring can be ordered to establish a trans-influence series of anionic ligands X and neutral ligands L, which correlates well with, but is more extensive than, that based earlier on PtMe(dppe) complexes. Single-crystal X-ray structural analysis of trans-[Pt(κ 1 -OCOCF 3 )(κ 2 -C 6 H 3 -5-Me-2-PPh 2 )(PPh 2 -4-tol)] (trans-

Quantification of cis and trans influences in [PtX(PPh3)3]+ complexes. A 31P NMR study

“…The trans sequence of the halides is in accordance with the suggestion that there is an inverse correlation between the trans influence of a ligand and its electronegativity [37,38].…”

“…The low trans ability of NO 3 may have this origin: its interaction with Pt(II) has a rather high ionic character [14], making the Pt orbitals available for a strong interaction in the trans position. As for the low trans weight of F, besides its high electronegativity (see above [37,38]), one could envisage that its bond with Pt involves a 2s-6s interaction, originating a rather weak Pt-F bond (compound 7 is little stable [34]), allowing a strong interaction in the trans position.…”

Formation of heterobinuclear Pt–Au complexes by chelate ring-opening of cis-[Pt(κ2-C6R4PPh2)2] (R = H, F)

“…The most highly shielded resonance (d À63 for 4, d À66 for 5) is typical of a phosphorus atom in a four-membered ring [9], the 1 J(PteP) values [1232 Hz for 4, 1671 Hz for 5] being as expected for P trans to C 6 H 4 or C 6 F 4 , respectively, in the strained ring environment [10,11]. A resonance in the range d 10e20 is assigned to PPh 3 coordinated to Pt, on the basis of its chemical shift and the 1 J(PteP) values (1990 Hz for 4, 2379 Hz for 5).…”

Organophosphines in Cis-PtP2CCl Derivatives Structural Aspects

“…[54] and orthorhombic [Pt(PMe3){η 2 -tbtpb}(Cl)][55]. Each chelating-P,C ligand forms a metallocyclic ring: in the[53] first example a three-membered 41° (PC) ring.…”

“…Each chelating-P,C ligand forms a metallocyclic ring: in the[53] first example a three-membered 41° (PC) ring. In the second[54] a four-membered 69.8° (PCC) ring, and in the third[55] a five-membered, 82.6° (PC2C) ring. The mean Pt-L bond distances elongate in the order: 2.225 Å (trans to Cl) < 2.25 Å (C, trans to P) < 2.27 Å (P, trans to P) < 2.41 (Cl, trans to P).…”