Synthesis and characterization of mono- and binuclear platinum complexes containing terminal and bridging diynyldiphenylphosphine ligands

Abstract

A series of mononuclear platinum complexes containing diynyldiphenylphosphine ligands [cis-Pt(C(6)F(5))(2)(PPh(2)C[triple bond]CC(6)H(4)C[triple bond]CR)L](n)(n= 0, L = tht, R = Ph 2a, Bu(t)2b; L = PPh(2)C[triple bond]CC(6)H(4)C[triple bond]CR, 4a, 4b; n=-1, L = CN(-), 3a, 3b) has been synthesized and the X-ray crystal structures of 4a and 4b have been determined. In order to compare the eta2-bonding capability of the inner and outer alkyne units, the reactivity of towards [cis-Pt(C(6)F(5))(2)(thf)(2)] or [Pt(eta2)-C(2)H(4))(PPh(3))(2)] has been examined. Complexes coordinate the fragment "cis-Pt(C(6)F(5))(2)" using the inner alkynyl fragment and the sulfur of the tht ligand giving rise the binuclear derivatives [(C(6)F(5))(2)Pt(mu-tht)(mu-1kappaP:2eta2-C(alpha),C(beta)-PPh(2)C[triple bond]CC(6)H(4)C[triple bond]CR)Pt(C(6)F(5))(2)](R = Ph 5a, Bu(t)5b). The phenyldiynylphosphine complexes 2a, 3a and 4a react with [Pt(eta2)-C(2)H(4))(PPh(3))(2)] to give the mixed-valence Pt(II)-Pt(0) complexes [((C(6)F(5))(2)LPt(mu-1kappaP:2eta2)-C(5),C(6)-PPh(2)C[triple bond]CC(6)H(4)C[triple bond]CPh))Pt(PPh(3))(2)](n)(L = tht 6a, CN 8a and PPh(2)C[triple bond]CC(6)H(4)C[triple bond]CPh 9a) in which the Pt(0) fragment is eta2-complexed by the outer fragment. Complex 6a isomerizes in solution to a final complex [((C(6)F(5))(2)(tht)Pt(mu-1kappaP:2eta2)-C(alpha),C(beta)-PPh(2)C[triple bond]CC(6)H(4)C[triple bond]CPh))Pt(PPh(3))(2)]7a having the Pt(0) fragment coordinated to the inner alkyne function. In contrast, the tert-butyldiynylphosphine complexes 2b and 3b coordinate the Pt(0) unit through the phosphorus substituted inner acetylenic entity yielding 7b and 8b. By using 4a and 2 equiv. of [Pt(eta2)-C(2)H(4))(PPh(3))(2)] as precursors, the synthesis of the trinuclear complex [cis-((C(6)F(5))(2)Pt(mu-1kappaP:2eta2)-C(5),C(6)-PPh(2)C[triple bond]CC(6)H(4)C[triple bond]CPh)(2))(Pt(PPh(3))(2))(2)]10a, bearing two Pt(0)(PPh(3))(2)eta2)-coordinated to the outer alkyne functions is achieved. The structure of 7a has been confirmed by single-crystal X-ray diffraction.

Ethynyltolan Platinum Complexes with (Arylalkynyl)phosphane Ligands

“…These values are unexceptional and similar to those found in other X-ray crystallographically characterised mononuclear P-coordinated alkynylphosphane- [8,10,14,15,26,27,61,62] or σ-alkynylplatinum [63][64][65][66][67][68][69][70][71][72][73][74][75][76][77][78] complexes. The C 6 H 4 group and the phenyl rings on each ethynyltolan ligand are nearly coplanar [dihedral angles: 2.89 (15) bon atoms of the proximal alkyne units (less than 3.4 Å, twice the van der Waals radius of the carbon atom).…”

“…[7,48] PPh 2 CϵC-X-CϵCR ligands are able to offer higher coordination and reactivity possibilities due to the extension of the delocalised π-system. However, they have only been used as precursors of polymetallic complexes [10,15,[49][50][51][52] and in P-C bond activation or intramolecular coupling reactions [51,[53][54][55] on a few occasions. With the aim of exploring the η 2 -bonding capability of two P-coordinated diphenylphosphane ligands towards a second metal centre as a way of inducing alkyne coupling, we have previously studied the reactivity of cis-[MX 2 (PPh 2 CϵCR) 2 ] (M = Pd, Pt; X = Cl, [2] C 6 F 5 , [4,8,11] CϵCRЈ; [3] R = Ph, tol, tBu; RЈ = Ph, tBu) towards the solvate complex cis-[Pt(C 6 F 5 ) 2 (thf) 2 ] (thf = tetrahydrofuran).…”

15 Noble metals

“…272 In an interesting study, the position of coordination of {Pt(C 6 F 5 ) 2 } or {Pt(PPh 3 ) 2 } fragments to the diynyldiphenylphosphine platinum complexes [Pt(C 6 F 5 ) 2 (CN)-(P(Ph 2 )-CMC-(C 6 H 4 )-CMC-R] [R = Ph or t-Bu] is controlled by the substituents (R) and the oxidation state of the platinum. 273 Similarly, the novel species cis-[Pt(CMCR) 2 (CN) 2 ] 22 [R = t-Bu or Ph] have been prepared and considered as building blocks in the generation of self-organized systems with a variable molecular architecture. In keeping with the interest in iridium and osmium, a rational synthesis of platinabenzenes has been explored.…”

Facile Single or Double C−H Bond Activation on a Cp* Ligand Promoted by the Presence of Alkynylphosphine Ligands

“…On the other hand, alkynylphosphines have been shown to be a very useful type of ligand with excellent promise in coordination chemistry, mainly due to their ability to coordinate via the phosphorus atom and/or the CC moiety, thus favoring the formation of a rich variety of homo- and heteropolynuclear species. – Furthermore, they present a varied and rich chemistry related to several processes, among which are (i) the phosphorus−carbon bond cleavage to generate phosphido and alkynyl fragments via interaction with metal carbonyl clusters, ,− (ii) their possible engagement in characteristic insertion reactions of the triple bonds ,− or their activation with electrophilic or nucleophilic substrates, − and also (iii) intermolecular coupling of the alkynyl moieties leading to the association of two coordinated alkynylphosphines. ,,− The last reactions are of particular interest, owing to the fact that they are employed in the synthesis of macrocyclic systems from bis(diphenylphosphino) complexes with high atom efficiency , and in the study of Bergman-cyclization processes of bis(phosphino)enediynes upon complexation to metal ions. ,, Our research group has obtained very interesting results in the study of these coupling reactions on platinum and palladium precursors containing at least two alkynylphosphines, having reported the formation of novel coordinated diphosphinonaphthalene or 1,2-diarylalkenyl-1,2-diphosphine ligands, activated by complexation of a “ cis -Pt(C 6 F 5 ) 2 ” fragment, , under thermal or photochemical conditions …”

“…On the other hand, alkynylphosphines have been shown to be a very useful type of ligand with excellent promise in coordination chemistry, 29 eropolynuclear species. [29][30][31][32][33][34][35][36][37][38][39][40][41][42][43][44][45][46][47] Furthermore, they present a varied and rich chemistry related to several processes, among which are (i) the phosphorus-carbon bond cleavage to generate phosphido and alkynyl fragments via interaction with metal carbonyl clusters, 29, [48][49][50] (ii) their possible engagement in characteristic insertion reactions of the triple bonds 35,[51][52][53][54][55] or their activation with electrophilic or nucleophilic substrates, [56][57][58] and also (iii) intermolecular coupling of the alkynyl moieties leading to the association of two coordinated alkynylphosphines. 31,52,[59][60][61][62][63][64][65][66] The last reactions are of particular interest, owing to the fact that they are employed in the synthesis of macrocyclic systems from bis(diphenylphosphino) complexes with high atom efficiency 61,62 and in the study of Bergmancyclization processes of b...…”