Syntheses, Luminescence Behavior, and Assembly Reaction of Tetraalkynylplatinate(II) Complexes:  Crystal Structures of [Pt(^tBu₃trpy)(C⋮CC₅H₄N)Pt(^tBu₃trpy)](PF₆)₃ and [Pt₂Ag₄(C⋮CC⋮CC₆H₄CH₃-4)₈(THF)₄]

Abstract

A series of tetraalkynylplatinate(II) complexes, (NBu(4))(2)[Pt(Ctbd1;CR)(4)] (R = C(6)H(4)N-4, C(6)H(4)N-3, and C(6)H(3)N(2)-5), and the diynyl analogues, (NBu(4))(2)[Pt(Ctbd1;CCtbd1;CR)(4)] (R = C(6)H(5) and C(6)H(4)CH(3)-4), have been synthesized. These complexes displayed intense photoluminescence, which was assigned as metal-to-ligand charge transfer (MLCT) transitions. Reaction of (Bu(4)N)(2)[Pt(Ctbd1;CC(5)H(4)N-4)(4)] with 4 equiv of [Pt((t)Bu(3)trpy)(MeCN)](OTf)(2) in methanol did not yield the expected pentanuclear platinum product, [Pt(Ctbd1;CC(5)H(4)N)(4)[Pt((t)Bu(3)trpy)](4)](OTf)(6), but instead afforded a strongly luminescent 4-ethynylpyridine-bridged dinuclear complex, [Pt((t)Bu(3)trpy)(Ctbd1;CC(5)H(4)N)Pt((t)Bu(3)trpy)](PF(6))(3,) which has been structurally characterized. The emission origin is assigned as derived from states of predominantly (3)MLCT [d(pi)(Pt) --> pi((t)Bu(3)trpy)] character, probably mixed with some intraligand (3)IL [pi --> pi(Ctbd1;C)], and ligand-to-ligand charge transfer (3)LLCT [pi(Ctbd1;C) --> pi((t)()Bu(3)trpy)] character. On the other hand, reaction of (Bu(4)N)(2)[Pt(Ctbd1;CCtbd1;CC(6)H(4)CH(3)-4)(4)] with [Ag(MeCN)(4)][BF(4)] gave a mixed-metal aggregate, [Pt(2)Ag(4)(Ctbd1;CCtbd1;CC(6)H(4)CH(3)-4)(8)(THF)(4)]. The crystal structure of [Pt(2)Ag(4)(Ctbd1;CCtbd1;CC(6)H(4)CH(3)-4)(8)(THF)(4)] has also been determined. A comparison study of the spectroscopic properties of the hexanuclear platinum-silver complex with its precursor complex has been made and their spectroscopic origins were suggested.

Homo‐ and Heteropolynuclear Platinum Complexes Stabilized by Dimethylpyrazolato and Alkynyl Bridging Ligands: Synthesis, Structures, and Luminescence

“…Alternatively, the transition may be viewed as an MLM'CT (M = Pt, M' = d 10 ) with intraligand alkynyl character. This assignment is similar to those previously made in related heteropolymetal h 2 -alkynyl bridging complexes (s-Pt, h 2 ···M) [132,133,135,136] though, as stated by Yam and co-workers, [136] in this type of system one should be aware that assignments of electronic transitions between metal and/or ligand localized orbitals are only rough approximations due to possible orbital mixing. In complexes 3 and 4 some contribution of ligand (dmpz)-to-M'A C H T U N G T R E N N U N G (d 10 ) LM'CT cannot be ex- [8] …”

“…The assignment of the radiative excited state(s) is uncertain but the emission seems to be characteristic of the formation of the hexanuclear central core. With reference to previous work on heteropolynuclear Pt IIcopper(i) and -silver(i) alkynyl bridging complexes [5,25,94,120,133,135,136,141,143] the strong and enhanced phosphorescence relative to the precursor is associated to the h 2 -platina alkyne [Pt-C CPh-Cu I ] entities. The emissive state is likely to derive from a 3 …”

Novel Luminescent Mixed‐Metal PtTl‐Alkynyl‐Based Complexes: The Role of the Alkynyl Substituent in Metallophilic and η2(π⋅⋅⋅Tl)‐Bonding Interactions

“…The novel, prominent low-energy absorption at 380 nm, which is absent in the precursor and is slightly solvent-dependent, is tentatively assigned to a metalÀalkynyl-to-metal cluster core [Pt(CCR) 4 !Pt 2 Tl 4 ] MLM'CT transition in accord with previous assignments in related systems. [63,71] In acetone, the PtTl 2 complex 3 shows two absorption bands at 328 and 360 nm, which are similar in energy to those observed for the homoleptic derivative (NBu 4 ) 2 ) and can be regarded as the spin-forbidden counterpart of the intense band, is clearly observed (see the Supporting Information, Figure S5) À complexes [72] with PtÀTl bonds indicate that the [PtPh 2 (CCPh) 2 ] fragments play a significant role in the highest-occupied orbitals, while the PtTl 2 or PtTl units make a notable contribution to the lowest-unoccupied orbitals. Similarly, we suggest that in complex 3 this band can be tentatively attributed to metalÀalkynyl-to-metal charge transfer [Pt/CCR!s[Pt,Tl(p z )], although some mixing of the target orbital with p*CCR cannot be excluded.…”

“…[55,56] In the past two decades, much has been discovered about the photoluminescence behavior of alkynylplatinum(ii) complexes, [57][58][59][60][61][62] but, in comparison, relatively little is understood about the emissive properties of heteropolynuclear platinum systems containing alkynyl bridging ligands. [63][64][65][66] Recent studies by us [67][68][69][70] and others [63,66] 8 ] by sandwiching naked Tl I centers through Tl I -alkyne interactions, [71] thus indicating that in these systems the Tl I centers have a stronger preference for the electron-rich alkynyl entities than for the basic Pt II center. Surprisingly, in similar reactions with heteroleptic cis-or transplatinate systems [Pt(C 6 F 5 ) 2 (CCR) 2 ] 2À (R = tBu, Ph), the platinum center has a higher affinity for thallium than for the alkynyl ligands, yielding six-coordinate platinum entities with two direct PtÀTl bonds that dimerize ([{trans,cis,cisPtTl 2 (C 6 F 5 ) 2 (CCPh) 2 } 2 ]) [72] or polymerize ([{trans,trans, trans-PtTl 2 (C 6 F 5 ) 2 (CCtBu) 2 } n ]), [73] in these cases through secondary Tl I Àalkynyl(C-a) contacts.…”

A Luminescent Heteronuclear Cluster Featuring an Unusual Cu6 Boat‐Shaped Core Assembled by Two Dialkynyl‐Cycloplatinated Units

“…[1,7,8,10,12,[14][15][16][17][18][19][20][21] In this area, considerable interest has been paid to Pt II -M I (M = Cu, Ag, Au) heterometallic alkynyl complexes due to their rich structural topology [22][23][24][25][26][27][28][29][30][31][32][33][34][35][36][37][38][39][40] and interesting spectroscopic and optical properties. [1,14,17,[41][42][43][44][45][46][47][48][49][50][51][52] In these systems, luminescence behavior is strongly influenced by the modification of the electron density of the CϵCR units through the variation of the R substituents, η 2 -M alkynyl bonding and also by metallophilic interactions (Pt···Pt, Pt···M, M···M). [1,<...>…”