60648-71-7

Upstream product

• 59967-54-3 [(iPr₃P)₂Pt^IICl₂] 
• 81602-78-0 bis(triisopropylphosphine)-3,3-dimethylplatinacyclobutane 
• 74080-74-3 trans-dichlorobis(tri-isopropylphosphine)platinum(II) 
• 6476-36-4 tris(1-methylethyl)phosphine 
• 60648-72-8 [Pt(PiPr₃)3] 

Relevant academic research and scientific papers

The Triboracyclopropenyl Dianion: The Lightest Possible Main-Group-Element Hückel π Aromatic

Hückel π aromaticity is typically a domain of carbon-rich compounds. Only very few analogues with non-carbon frameworks are currently known, all involving the heavier elements. The isolation of the triboracyclopropenyl dianion is presented, a boron-based analogue of the cyclopropenyl cation, which belongs to the prototypical class of Hückel π aromatics. Reduction of Cl2BNCy2 by sodium metal produced [B3(NCy2)3]2-, which was isolated as its dimeric Na+ salt (Na4[B3(NCy2)3]22 DME; 1) in 45 % yield and characterized by single-crystal X-ray diffraction. Cyclic voltammetry measurements established an extremely high oxidation potential for 1 (Epc=-2.42 V), which was further confirmed by reactivity studies. The Hückel-type π aromatic character of the [B3(NCy2)3]2- dianion was verified by various theoretical methods, which clearly indicated π aromaticity for the B3 core of a similar magnitude to that in [C3H3]+ and benzene.

Correlations and Contrasts in Homo- and Heteroleptic Cyclic (Alkyl)(amino)carbene-Containing Pt0 Complexes

An improved synthetic route to homoleptic complex [Pt(CAACMe)2] (CAAC=cyclic (alkyl)(amino)carbenes) and convenient routes to new heteroleptic complexes of the form [Pt(CAACMe)(PR3)] are presented. Although the homoleptic complex was found to be inert to many reagents, oxidative addition and metal-only Lewis pair (MOLP) formation was observed from one of the heteroleptic complexes. The spectroscopic, structural, and electrochemical properties of the zero-valent complexes were explored in concert with density functional theory (DFT) and time-dependent density functional theory (TD-DFT) calculations. The homoleptic [Pt(CAAC)2] and heteroleptic [Pt(CAAC)(PR3)] complexes were found to be similar in their spectroscopic and structural properties, but their electrochemical behavior and reactivity differ greatly. The unusually strong color of the CAAC-containing Pt0 complexes was investigated by TD-DFT calculations and attributed to excitations into the LUMOs of the complexes, which are predominantly composed of bonding π interactions between Pt and the CAAC carbon atoms. An improved synthetic route to homoleptic complex [Pt(CAACMe)2] and convenient routes to new heteroleptic complexes of the form [Pt(CAACMe)(PR3)] are presented. The reactivity, spectroscopic, structural, and electrochemical properties of the zero-valent complexes were explored in concert with DFT and time-dependent DFT calculations. The homoleptic [Pt(CAAC)2] and heteroleptic [Pt(CAAC)(PR3)] complexes were found to be similar in their spectroscopic and structural properties, but their electrochemical behavior and reactivity differ greatly (see figure).

Reactivity of Tetrahalo- and Difluorodiboranes(4) toward Lewis Basic Platinum(0): Bis(boryl), Borylborato, and Doubly Boryl-Bridged Platinum Complexes

The reaction of the tetrahalodiboranes(4) B2F4, B2Cl4, and B2Br4 with a Lewis basic platinum(0) complex led to the isolation of the cis-bis(difluoroboryl) complex cis-[(Cy3P)2Pt(BF2)2] (1) and the novel borylborato complexes trans-[(Cy3P)2Pt{B(X)-BX3}] (2, X = Cl; 3, X = Br), respectively. The trans influence of the borylborato group was found to be one of the strongest ever observed experimentally. Furthermore, the reactivity of little-explored diaryldifluorodiboranes(4) F2B-BMes2 and the new derivative F2B-BAn2 (An = 9-anthryl) toward a range of platinum(0) complexes was investigated. Reactions with relatively nonbulky platinum(0) complexes led to the formation of unsymmetrical cis-bis(boryl) complexes cis-[(R3P)2Pt(BF2)(BMes2)] (6, R = Me; 7, R = Et) as well as the first example of a fourfold-unsymmetrical bis(boryl) complex, [(Me3P)(Cy3P)Pt(BF2)(BMes2)] (12). The use of a more bulky Pt complex provided access to the unprecedented dinuclear bis(boryl) complexes [{(iPr3P)Pt}2(μ-BF2)(μ-BAr2)] (8, Ar = Mes; 9, Ar = An), which feature two different μ2-bridging boryl ligands.

Investigation of Steric Factors Involved in the Formation of Terminal Cationic Platinum Arylborylene Complexes

The abstraction of halido ligands from PtII diphosphine boryl complexes has previously been shown to yield one of two isomeric products: either T-shaped cationic boryl complexes or square-planar cationic borylene complexes. However, the latter product has only been observed in one case, that of a mesitylboryl ligand, which converts to a mesitylborylene ligand upon halido abstraction. In an effort to test the efficacy of this reaction in the presence of different steric and electronic influences, PtII diphosphine boryl complexes were prepared with both 4-tert-butylphenyl and duryl (2,3,5,6-tetramethylphenyl) groups. Halide abstraction from the 4-tert-butylphenyl complex resulted in a T-shaped cationic boryl complex. However, subjecting the duryl-substituted complexes to the same conditions exclusively results in terminal cationic borylene complexes, a difference we attribute to the greater steric hindrance between the boron-bound bromide and the methyl groups at the 2- and 6-positions of the duryl group. This outcome indicates that the electronic effect of alkylation at the para position is not a factor for this borylene formation reaction. (Chemical Equation Presented).

Evidence for a strong trans influence of the diboran(4)yl ligand

Diboran(4)yl PtII complexes: Selective oxidative addition of one B-I bond in B2(NMe2)2I2 to [Pt(PiPr3)2] affords a trans-diboran(4)yl platinum(II) complex (see scheme; ArF=3,5-(CF3)2C 6H3). Comparison of its Pt-I bond lengths and the Pt-Br bond lengths of its bromine analogue with related species served to evaluate the trans influence of the ligand. The trans influence enabled facile halide abstraction to generate T-shaped 14-electron diboran(4)yl platinum(II) complexes.

Competing C-F activation pathways in the reaction of Pt(0) with fluoropyridines: Phosphine-assistance versus oxidative addition

A survey of computed mechanisms for C-F bond activation at the 4-position of pentafluoropyridine by the model zero-valent bis-phosphine complex, [Pt(PH3)(PH2Me)], reveals three quite distinct pathways leading to square-planar Pt(II) products. Direct oxidative addition leads to cis-[Pt(F)(4-C5NF4)(PH3)(PH2Me)] via a conventional 3-center transition state. This process competes with two different phosphine-assisted mechanisms in which C-F activation involves fluorine transfer to a phosphorus center via novel 4-center transition states. The more accessible of the two phosphine-assisted processes involves concerted transfer of an alkyl group from phosphorus to the metal to give a platinum(alkyl)(fluorophosphine), trans-[Pt(Me)(4-C5NF 4)(PH3)(PH2F)], analogues of which have been observed experimentally. The second phosphine-assisted pathway sees fluorine transfer to one of the phosphine ligands with formation of a metastable metallophosphorane intermediate from which either alkyl or fluorine transfer to the metal is possible. Both Pt-fluoride and Pt(alkyl)(fluorophosphine) products are therefore accessible via this route. Our calculations highlight the central role of metallophosphorane species, either as intermediates or transition states, in aromatic C-F bond activation. In addition, the similar computed barriers for all three processes suggest that Pt-fluoride species should be accessible. This is confirmed experimentally by the reaction of [Pt(PR 3)2] species (R = isopropyl (iPr), cyclohexyl (Cy), and cyclopentyl (Cyp)) with 2,3,5-trifluoro-4-(trifluoromethyl)pyridine to give cis-[Pt(F){2-C5NHF2(CF3)}(PR3) 2]. These species subsequently convert to the trans-isomers, either thermally or photochemically. The crystal structure of cis-[Pt(F){2-C 5NHF2(CF3)}(PiPr3)2] shows planar coordination at Pt with r(F-Pt) = 2.029(3) A and P(1)-Pt-P(2) = 109.10(3)°. The crystal structure of frans-[Pt(F){2-C5NHF 2(CF3)}(PCyp3)2] shows standard square-planar coordination at Pt with r(F-Pt) = 2.040(19) A.

Synthesis and study of platinum silylene complexes of the type (R 3P)2Pt=SiMes2 (Mes = 2,4,6-trimethylphenyl)

The synthesis and characterization of neutral platinum silylene complexes (R3P)2Pt=SiMeS2 (R = i-Pr (1) or cyclohexyl (2), Mes = 2,4,6-trimethylphenyl) is reported. The dimesitylsilylene ligand in 2 is displaced by a number of ligands including phosphines, alkenes, alkynes, and O2. Complex 2 reacts with ROH substrates (R = H, Me, Et) to give (Cy3P)2Pt and Mes2Si(OR)(H) and with H 2 to give trans-(Cy3P)2Pt(H)SiHMeS2 (3). Reaction of H2SiMeS2 with (Cy3P)2Pt gave cis-(Cy3P)2Pt(H)SiHMeS2 (4). EXSY NMR experiments of 4 reveal that exchange of silicon and platinum hydrides occurs via reductive elimination - oxidative addition and not via a silylene intermediate.

Reductive Elimination of a Carbon-Carbon Bond from Bis(trialkylphosphine)-3,3-dimethylplatinacyclobutanes Produces Bis(trialkylphosphine)platinum(0) and 1,1-Dimethylcyclopropane

The thermal decompositions of several platinacyclobutanes-bis(triethylphosphine)-(1), bis(triisopropylphosphine)-(2), and bis(tricyclohexylphosphine)-3,3-dimethylplatinacyclobutane (3) -have been examined in cyclohexane solution.Decomposition of 1 proceeds heterogeneously: it products platinum metal, neopentane, 1,1-dimethylcycloprorane, and ethilene and seems to be autocatalytic.Decompositions conducted using reaction mixtures containing mercury(0) proceed homogeneously and produce predominately 1,1-dimethylcyclopropane; any platinum metal produced is apparently amalgamated by Hg(0) and rendered catalytically inactive.Thermal decompositions of 2 and 3 proceed homogeneously, even in the absence of Hg(0), and yield 1,1-dimethylcyclopropane, bis(trialkylphosphine)platinum(0), and small quantity of neopentane.The rates of the decomposition decreases by addition of trialkylphosphine, and a study of these dependence of the rate on concentration of added phosphine for 2 indicates that one phosphine dissociates to produce a three-coordinate platinum(II) intermediate prior to reductive elimination of 1,1-dimethylcyclopropane.The Arrhenius activation parameters for decomposition of 2 and 3 are respectively Ea=46+/-3 kcal mol-1, log A=23+/-2 and Ea=42+/-2 kcal mol-1, log A=21+/-1.Substitution of deuterium for hydrogen in the triisopropylphosphine groups of 2 produces no change in the rate of the reaction.We cannot distinguish between mechanisms in which reductive elimination of 1,1-dimethylcyclopropane occurs directly from the three-coordinate intermediate and those in which oxidative addition of a C-H bond to platinum bycyclometalation of the phosphine produces a Pt(IV) intermediate in a step preceding rate-limiting reductive elimination of 1,1-dimethylcyclopropane.

A 31P Nuclear Magnetic Resonance Investigation of the Structure, Equilibria, and Kinetics of in Solution

The compounds (L = PMe3, PMe2Ph, PMePh2, PEt3 or PBun3), n3, P(p-tolyl)3, P(CH2Ph)3, PPri3, or P(C6H11)3>, and i3, P(C6H11)3, or PBut2Ph> have been prepared and shown to exist in solution.In the cases of L = PMePh2, PEt3, PBun3, n = 3 and L = PPri3, P(C6H11)3, n = 2 it has proved possible to measure the equilibrium constant, ΔH, and ΔS for n+1>n> + L.For , , , , n3)4>, i3)3> and 3>, the tertiary phosphine exchange is dissociative, while for 13)2> and 2> associative exchange occurs.In the case of and n3)3> both associative and dissociative exchange occur, the relative rates of which depend on the temperature and concentration of free tertiary phosphine.In the cases of i3)2> and2> a marked solvent effect has been found and attributed to possible toluene co-ordination producing in equlibrium with .No evidence is found for steric crowding affecting ΔH or ΔH++, but ΔS and ΔS++ are affected due to interpenetration of the ligands and resulting loss of motional freedom, while previously it has been assumed that interligand steric crowding destabilizes the molecule via enthalpy term.