Acetylenes attached to poly(pentafluorophenyl)platinum(II) moieties. Syntheses and molecular structures of cis-[Pt(C₆F₅)₂(PhCCPh)₂] and [NBuⁿ₄][Pt(C₆F₅)₃(PhCCPh)]

Abstract

The complexes cis-[Pt(C,F,),(RCrCR),] ( R = Et l a or Ph 1 b) have been prepared by treating cis-[Pt(C,F,),(thf ),] (thf = tetrahydrofuran) with the appropriate alkyne. They undergo facile ligand exchange with either cis-[Pt(C,F,),(thf ),I or [NBu",],[Pt(C,F,),] giving rise respectively to neutral cis-[Pt( C,F,),(thf ) ( RCECR)] 2 or anionic [NBu",] [Pt(C,F,),( PhCrCPh)] 7b mono(q2-alkyne) derivatives. A series of mono(q2-alkyne) complexes of formulae ciS-[Pt(C,F,),L( R C K R ) ] ( L = pyridine 3a, 3b; PPh, 4a; SbPh, 5b; or CO 6a, 6b) and [N(PPh,),][Pt(C,F,),(EtC=CEt)] 7a has also been prepared. None of these complexes except 7b shows v(C=C) absorptions in their IR spectra. The molecular structures of complexes 1 b and 7b have been established by X-ray diffraction studies: 1 b, monoclinic, space group C2/c, a = 19.1 77(4), b = 8.4971 (4), c = 19.790(3) A, p = 103.297(14)" and Z = 4 (C, symmetry imposed); 7b, monoclinic, space group P2,/c, a = 10.5179(9), b = 17.5834(20), c = 25.369(5) A, p = 99.376(11)" and Z = 4. Parameters within the acetylene moiety of 1 b suggest that the platinum-alkyne n-back bonding is minimal.Transition metal-acetylene complexes form a well defined area of study in organometallic chemistry, the interest in which can be ascribed to the wide variety of chemical processes undergone by alkynes when attached to mono-or poly-nuclear metal fragments' as well as to the richness of their co-ordination modes.,In contrast to the plethora of olefin complexes of platinum(i1) presently known, the number of simple platinum(ir) mono(acety1ene) derivatives is more limited.3 This is primarily due to the activity shown by some platinum(I1) complexes in effecting oligo-or poly-merization of acetylene^,^ including cyclization proce~ses,~ and to the ability of alkynes to insert into Pt-E bonds (E = halide,6 H7 or alkyl'). Since M-C,F, bonds are usually reluctant to undergo insertion reactions,' the choice of pentafluorophenyl derivatives as starting materials to prepare stable platinum(1r) acetylene complexes seemed appropriate. Accordingly, we here report the synthesis of the first bis(q'-alkyne)platinum(II) complexes and that of a number of mono(q2-alkyne)platinum(Ii) complexes. Some of the results have been briefly communicated. ' Results and DiscussionThe complex cis-[Pt(C,F,),(thf),] (thf = tetrahydrofuran) reacts either with hex-3-yne or with diphenylacetylene in 1:2 molar ratio to give in high yields the bis(q2-alkyne) complexes cis-[Pt(C,F,),(RC=CR),] (R = Et l a or Ph lb) as white, air-stable solids [equation (l)]. Analytical and relevant cis-[Pt(C,F,),(thf),] + 2RC&R ---+

Pentafluorophenylplatinum complexes containing η1- or η2-aryl–Pt interactions. Crystal structure of cis-[Pt(C6F5)2-({NC5H4[CH(η2-Ph)Ph]-2}-κN)]·0.5C6H5Me

“…1, the 2-(diphenylmethy1)pyridine molecule is bonded to the cis-Pt(C,F,), fragment through the N atom with additional q2-aryl-metal interaction from the C (19) and C(20) atoms of a phenyl ring. The Pt-C distances for this qz interaction [Pt-C(19) 2.317 (10), Pt-C(20) 2.390 (13) A] are similar to the shorter distance found in previous q2aryl-Pt compounds which have been structurally characterised. '' The co-ordinated phenyl group is essentially planar and the C-C distances in the ring are equal within the experimental error.…”

“…Suitable crystals for X-ray studies were grown by slow evaporation of a CHC13 solution of 2 at 4 "C in a toluene-saturated atmosphere. Data were collected in a Siemens STOE/AED-2 four-circle diffractometer with an Oxford Cryosystem low-temperature device at 233 K, scan range 10) 1007( 9) 1087( 10) 1288 (10) 1397( 1 1) 13 10( 10) 793( 6) 967( 7) 1337( 7) 1577( 7) 1438( 7) 2579( 10) 2820( 12) 4084( 16) 5 100( 13) 4948( 13) 368 1 ( 1 3) 1 843( 8) 4241( 9) 6290( 8) 5959( 8) 3558( 7) 455( 8 10) 181( 10) 648( 1 1 ) 1889( 11) 2662( 10) 453( 6) -1050( 6) -151( 7) 2334( 7) 388 l( 6) 3746( 10) 3220( 12) 3506 ( 15) 431 l( 17) 4869( 14) 4587( 14) 2414( 7) 2928( 9) 4547 ( 10) 567 1 (10) 5 1 3 l( 9) 4412( 8 27) 4720( 19) 4489(25) -5 (13) 4809( 1 1 ) 40 1 7( 10) 2638( 10) 2325( 10) 3264( 1 1) 2850( 12) 1558( 13) 635( 12) 980( 10) 2296( 1 1) 1662( 11) 1342( 11) 1658( 1 3) 22...…”

Twistophane Macrocycles with Integrated 6,6′-Connected-2,2′-Bipyridine Units: A New Lead Class of Fluorescence Sensors for Metal Ions

“…The latter observation of a nonlinear time‐dependent change in emissive species suggests that they are being generated by a reaction mechanism between 3 and metal ions that is more complex than originally anticipated. The expanded range of conformational states available to 3 , coupled with the additional ability of Cu II , Ag I , Hg II and Pd II to form interactions of varying strength with alkynes and in some cases phenyl rings,18c, 43a–43c indicates that a large number of ground and excited state coordination structures may potentially be accessible to 3 . The mechanism of complexation of a given cation by 3 may therefore involve multiple sequential hopping or riding of ions over the cyclophane framework as it passes through different conformations, until the final thermodynamically preferred species or mixture of entities are formed.…”

Synthesis and Reactivity of Square‐Planar PtII–η1‐Hydrocarbyl Complexes Containing cis‐Coordinated Olefin or Alkyne

“…cis-[Pt(C 6 F 5 ) 2 (EtCϵCEt) 2 ](IV-1) [35] cis-[Pt(C 6 F 5 ) 2 (PhCϵCPh) 2 ] (IV-2) [35] cis-[Pt(C 6 F 5 ) 2 (tht)(EtCϵCEt)] (IV-3) [35] cis-[Pt(C 6 F 5 ) 2 (tht)(PhCϵCPh)] (IV-4) [35] cis-[Pt(C 6 F 5 ) 2 (py)(EtCϵCEt)] (IV-5) [35] cis-[Pt(C 6 F 5 ) 2 (py)(PhCϵCPh)] (IV-6) [35] cis-[Pt(C 6 F 5 ) 2 (PPh 3 )(EtCϵCEt)] (IV-7) [35] cis-[Pt(C 6 F 5 ) 2 (SbPh 3 )(PhCϵCPh)] (IV-8) [35] cis-[Pt(C 6 F 5 ) 2 (CO)(EtCϵCEt)] (IV-9) [35] cis-[Pt(C 6 F 5 ) 2 (CO)(PhCϵCPh)] (IV-10) [35] [Pt(C 6 F 5 ) 3 (PhCϵCPh)][N(PPh 3 ) 2 ] (IV-11) [35] [PtPh(MeCϵCMe)(phen)](BF 4 ) (IV-12) [36] This class of compounds is the less represented of the four types, because of the enhanced reactivity of the adjacent hydrocarbyl ligands. Thus, the only examples of stable complexes of type IV (IV-1 to IV-12) are decorated with pentafluorophenyl rings, [35] which are quite reluctant to undergo insertion processes.…”

“…Thus, the only examples of stable complexes of type IV (IV-1 to IV-12) are decorated with pentafluorophenyl rings, [35] which are quite reluctant to undergo insertion processes. Dialkyne complexes IV-1 and IV-2 were obtained by substituting thf from a diaryl precursor (Scheme 22), and, in turn, they were converted into www.eurjic.orgmonoalkyne species (IV-3 to IV-10) by reaction with other donor molecules (tht, py, PPh 3 , SbPh 3 , CO).…”