Dinuclear, Tricyclometallated Platinum(II) Derivatives − Substitution Reactions and Reactivity of the Platinum−Carbon Bonds

Abstract

In the recently reported dinuclear cyclometallated species [Pt 2 (R)(L)(DMSO) 2 ] [H 3 L = 6-phenyl-2,2Ј-bipyridine; R = Me (1a), Ph (1b)] the threefold deprotonated ligand L links the two platinum atoms acting as an NЈ,C(3) and a C,N,C donor. Aspects of their reactivity have been studied first with regards to the substitution of the two DMSO ligands, which are coordinated to the platinum atom trans to a nitrogen and a carbon atom, respectively. Substitution of DMSO with neutral two-electron donors affords several new species, all having the same bridging ligand L: [Pt 2 (R)(L)(LЈ) 2 ] [LЈ = PPh 3 (2a, 2b), CO (3a, 3b)] and [Pt 2 (R)(L)(LЈ)(DMSO)] [LЈ =3,5-Me 2 -py (4a)]. The potentially bidentate diphosphane Ph 2 P(CH 2 ) 3 PPh 2 (dppp) gives a more complex species having both chelating and bridging dppp ligands [{Pt(Me)(L)(dppp)} 2 (µ-dppp)] (5a). The reactivity of the platinum−carbon bonds with HCl has been studied in complexes 1a, 1b and 2a, 2b and found to be strongly dependent on the nature of the ancillary ligands. To discern the most labile of the four metal−carbon bonds, the reaction has been

Luminescent PtII Complexes of Tridentate Cyclometalating 2,5‐Bis(aryl)‐pyridine Ligands

“…[1,2] Having the same shape and electronic configuration as 2,2′:6′,2′′-terpyridine (terpy), [3] the (Phbpy) -anion provides very stable tridentate binding and the cyclometalation, requiring C-H activation of the phenyl core, can be carried out at moderate conditions, usually by heating suitable Pt II or Pd II precursors and the C-H functionalised protoligands (ligand precursors, prior to metalation). [1,2,[4][5][6][7][8][9][10][11][12][13][14] Very soon after their initial use, it was found that many Pt II derivatives of the Phbpy ligand show intense luminescence, some even at ambient temperature. [11,[15][16][17][18][19] One reason lies in the destabilisation of dark metal-centred excited states associ-to 0.44 in PMMA matrices.…”

“…Tridentate cyclometalating ligands, such as the prototypical 6‐(phen‐2‐yl)‐2,2′‐bipyridine (Phbpy) – (Scheme ), have been used in organoplatinum(II) and organopalladium(II) chemistry since the 1990s, Having the same shape and electronic configuration as 2,2′:6′,2′′‐terpyridine (terpy), the (Phbpy) – anion provides very stable tridentate binding and the cyclometalation, requiring C–H activation of the phenyl core, can be carried out at moderate conditions, usually by heating suitable Pt II or Pd II precursors and the C–H functionalised protoligands (ligand precursors, prior to metalation) , , …”

Palladium(II) Complexes of Ambidentate and Potentially Cyclometalating 5‐Aryl‐3‐(2′‐pyridyl)‐1,2,4‐triazine Ligands

“…Tridentate cyclometalating ligands, such as the prototypical 6‐phenyl‐2,2′‐bipyridine (HPhbpy) (Scheme ), have been used in organopalladium(II) and ‐platinum(II) chemistry since the 1990s Having the same shape and electron configuration as 2,2′:6′,2′′‐terpyridine (terpy), the anion (Phbpy) – provides very stable tridentate binding, and the cyclometalation requiring C–H activation of the phenyl core can be carried out at moderate conditions, usually heating suitable Pd II or Pt II precursors and the C–H functionalised protoligands (ligand precursor prior to metalation) (Scheme ) . Recently, we came across the interesting class of 5‐aryl‐3‐(2′‐pyridyl)‐1,2,4‐triazines [PyTZ(aryl)] as versatile precursors for HPhbpy derivatives or other highly substituted pyridines (Scheme ) , …”

Experimental and Theoretical Studies of the Factors Affecting the Cycloplatination of the Chiral Ferrocenylaldimine (SC)-[(η5-C5H5)Fe{(η5-C5H4)–C(H)=N–CH(Me)(C6H5)}]

“…A few examples of cyclometallated Pt(II) compounds with (C,N,C) 2− pincer ligands have been reported [49][50][51][52], and thus the activation of a σ(C Ph -H] and a σ(C Fc -H] bond to give compounds 10 or 11 ( Figure 3) cannot be disregarded. Furthermore, and since several groups have achieved cylometallated Pt(IV) complexes in the reaction of cis-[PtCl2(dmso)2] with N-donor ligands [23,53,54], the formation of the platinum(IV) derivatives cannot be ruled out either.…”