σ-Donor–σ-acceptor plumbylene ligands: synergic σ-donation between ambiphilic Pt0 and Pbii fragments

Abstract

Mono- and diplatinum plumbylene complexes are prepared in which the bonding comprises synergic σ donation between the Pt and Pb atoms. The bonding distinguishes the complexes from both the classical Fischer carbene bonding model and M→Pb dative-only bonding. The Pt-Pb bond of the monoplatinum complex is stable, while the diplatinum complex reversibly loses one Pt fragment.

Platinum Complexes Containing Pyramidalized Germanium and Tin Dihalide Ligands Bound through σ,σ ME Multiple Bonds

“…Again, it was possible to detect 195 Pt{ 1 H} ( δ =−5259 ppm, 1 J (P,Pt)=4240 Hz) and 119 Sn{ 1 H} NMR resonances ( δ =473 ppm). Moreover the shifts of the resonances in the 31 P{ 1 H} and 195 Pt{ 1 H} NMR spectra are in agreement with other known adducts between platinum(0) fragments and other Lewis acids (e.g., BeCl 2 , AlCl 3 )11 and the heavier Group 14 analogue PbCl 2 4…”

“…However, the slightly longer PtSn distances in compound 5 are likely due to the added steric hindrance of the second [Pt(PCy 3 ) 2 ] moiety. For comparison, the d rel values of the similar published compounds I (0.941), II (1.01), III (0.968), and PtPbPt (0.981/0.989) are for the most part higher than those in this study 4. 7, 8 Furthermore, the coordination of an ECl 2 fragment to an [L 2 Pt] fragment has been analyzed by using the M‐E‐{midpoint‐Cl‐Cl} angles, which describe the degree of orthogonality of the Pt to the Cl‐E‐Cl plane.…”

“…The UV/Vis spectrum of the diplatinum compound 5 shows a very intense signal at λ =553 nm, which corresponds to the HOMO→LUMO transition calculated to be at λ =562 nm. This is a characteristic signal that becomes dominant when both [Pt(PCy 3 ) 2 ] units are definitively bound to SnCl 2 4. In contrast to the analogous diplatinum lead compound, in complex 5 there is no partial dissociation in solution, evidenced by the strong absorption band at λ =553 nm at ambient temperature.…”

“…( II , Figure 1),8 and ourselves ( III , Figure 1). 4 A study of the Cambridge Crystallographic Database2 shows that these complexes are the most pyramidalized of all non‐base‐stabilized MER 2 complexes. However, many planar ER 2 complexes of heavier tetrels are also known 9.…”

“…As the previously reported dihaloplumbylene ligand4 exhibited extreme pyramidalization at the lead atom, this study was intended to prepare dihalogermylene and ‐stannylene complexes of platinum(0), in order to determine if these too showed pyramidalization of the Group 14 center. Herein, we present the synthesis of the first mononuclear, base‐free dihalogermylene and ‐stannylene complexes with metal fragments, one of which is found to be the most highly pyramidalized MER 2 complex ever structurally characterized.…”