Synthesis and Reactivity of a Neutral, Three-Coordinate Platinum(II) Complex Featuring Terminal Amido Ligation

Small Molecule Activation with N,NR-MIC Platinum Complexes

The reaction of platinum complex trans-[1] bearing an N,NEt-imidazolide ligand with bis(diphenylphosphino)ethane (dppe) or bis(dicyclohexylphosphino)ethane (dchpe) yields the dinuclear MIC complexes [2]I₂ or the mononuclear MIC complex [3]I, respectively. Whereas dinuclear [2]I₂ does not react with elemental hydrogen, the mononuclear complex [3]I splits elemental hydrogen under mild reaction conditions with formation of hydride complex [4]I and N-ethylimidazole. Dinuclear complex [3]I activates CS₂ with formation of complex [5]I featuring the CS₂ molecule bound through the carbon atom to the MIC nitrogen atom and one sulfur atom coordinating to the platinum center.

Dehydrogenative B-H/C(sp3 )-H Benzylic Borylation within the Coordination Sphere of Platinum(II)

The first examples of stoichiometric dehydrogenative B-H/C(sp³ )-H benzylic borylation reactions, which are of relevance to catalytic methylarene (di)borylation, are reported. These unusual transformations involving a (κ² -P,N)Pt(η³ -benzyl) complex, and either pinacolborane or catecholborane, proceed cleanly at room temperature. Density functional calculations suggest that borylation occurs via successive σ-bond metathesis steps, whereby a Pt^II -H intermediate engages in C(sp³ )-H bond activation-induced dehydrogenation.

One-Electron Oxidation of [M(P(t) Bu3 )2 ] (M=Pd, Pt): Isolation of Monomeric [Pd(P(t) Bu3 )2 ](+) and Redox-Promoted C-H Bond Cyclometalation

Oxidation of zero-valent phosphine complexes [M(P(t) Bu3 )2 ] (M=Pd, Pt) has been investigated in 1,2-difluorobenzene solution using cyclic voltammetry and subsequently using the ferrocenium cation as a chemical redox agent. In the case of palladium, a mononuclear paramagnetic Pd(I) derivative was readily isolated from solution and fully characterized (EPR, X-ray crystallography). While in situ electrochemical measurements are consistent with initial one-electron oxidation, the heavier congener undergoes C-H bond cyclometalation and ultimately affords the 14 valence-electron Pt(II) complex [Pt(κ(2) PC -P(t) Bu2 CMe2 CH2 )(P(t) Bu3 )](+) with concomitant formation of [Pt(P(t) Bu3 )2 H](+) .