Matthew S. McCready

The University of Western Ontario, London, Ontario, Canada

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Publications (12)25.94 Total impact

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    ABSTRACT: The reagents 1,2-C6H4(CH[double bond, length as m-dash]NR)(SMe), R = CH2CH2NMe2 or Ph, react with [Pt2Me4(μ-SMe2)2] by oxidative addition of the aryl-sulfur bond to give the corresponding crystalline binuclear platinum(iv) compounds [Pt2Me4(μ-SMe)2(κ(2)-C,N-C6H4-2-CH[double bond, length as m-dash]NR)2], as the isomers with Ci (R = CH2CH2NMe2 or Ph) or C1 (R = Ph) symmetry. These first examples of C-S bond activation at platinum(ii) occur easily at room temperature, and the reactions give complex equilibria of isomeric products, from which the isolated compounds crystallise.
    Chemical Communications 06/2013; · 6.38 Impact Factor
  • Kyle R Pellarin, Matthew S McCready, Richard J Puddephatt
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    ABSTRACT: The complexes [PtMe2(NN)], NN = 2,2'-bipyridine = bipy, ; NN = di-2-pyridylamine = dpa, ; NN = di-2-pyridyl ketone = dpk, , NN = 4,4'-bis(ethoxycarbonyl)-2,2'-bipyridine, bebipy, react with m-chloroperoxybenzoic acid to give the platinum(iv) complexes [Pt(OH)(O2C-3-C6H4Cl)Me2(NN)], NN = bipy, , or [Pt(OH)(OH2O2C-3-C6H4Cl)Me2(NN)], NN = bipy, ; dpa, ; bebipy, , or [Pt(OH)2Me2(dpkOH)]3[Pt(OH)(OH2)Me2(dpkOH)][H(O2C-3-C6H4Cl)2]·2MeOH, 3··2MeOH. The reactions are proposed to occur by a polar oxidative addition mechanism, followed in most cases by the coordination of water. Complex crystallises as a supramolecular polymer, the compound 3··2MeOH crystallises as a supramolecular sheet structure, and easily forms a gel, all through strong intermolecular hydrogen bonding.
    Dalton Transactions 06/2013; · 3.81 Impact Factor
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    ABSTRACT: Organoplatinum(IV) complexes, [PtBrMe 2 (CH 2 -4-C 6 H 4 -NN-Ph)(NN)], containing trans-azobenzene functional groups, have been prepared by trans oxidative addition of BrCH 2 -4-C 6 H 4 -NN-Ph to the corresponding platinum(II) complexes [PtMe 2 (NN)], with NN = 2,2′-bipyridine, 1,10-phenanthroline, 4,4′-bis(ethoxycarbonyl)-2,2′-bipyridine, 1,4-di-2-pyridyl-5,6,7,8,9,10-hexahydrocycloocta[d]pyridazine. The complexes undergo efficient and almost quantitative trans−cis isomerization on irradiation of dilute solutions at 365 nm, as monitored by UV−visible spectroscopy, and somewhat less complete photolysis in concentrated solution, as monitored by 1 H NMR spectroscopy. The cis isomers undergo slow thermal isomerization back to the trans isomers, thus proving the photoswitching property of the complexes. ■ INTRODUCTION The synthesis of photoresponsive materials has attracted much interest for potential applications in optical switching and optoelectronics. 1,2 The incorporation of a transition metal into such materials can provide a photoswitching property to complement the magnetic, electrochemical, catalytic, or bio-logical properties of the metal center. 3 Among the well-known photoswitchable groups, azobenzene has been the most widely used. The popularity of the azobenzene group is due to the high efficiency of its reversible light-induced trans−cis isomer-ization, the significant structural change which occurs on isomerization with consequent changes in chemical and physical properties, and the high thermal and photochemical stability which allows many switching cycles to occur without any decomposition. 4 A typical case for switching in azobenzene derivatives is illustrated, in simplified form, in Figure 1. The trans−cis photoisomerization begins by excitation to the S 1 t
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    ABSTRACT: Complexes [PtMe2(NN)], with NN = 2,2′-bipyridine (bipy), 4,4′-di-tert-butyl-2,2′-bipyridine (bu2bipy), di-2-pyridylamine (dpa), or di-2-pyridyl ketone (dpk), react easily with phthaloyl peroxide to give a mixture of the chelate complex [PtMe2{κ2-O,O′-1,2-(O2C)2C6H4}(NN)], which was structurally characterized when NN = bu2bipy, and an oligomer or polymer [PtMe2{μ-κ2-O,O′-1,2-(O2C)2C6H4}(NN)]n. In the case with NN = dpa, no phthalate chelate complex is formed. These complexes are easily hydrolyzed, and the complexes cis-[PtMe2(OH){κ1-O-O2CC6H4-2-CO2H}(bipy)] and trans-[PtMe2{κ1-O-O2CC6H4-2-CO2H}(dpkOH)] have been structurally characterized. It is argued that the oxidative addition of phthaloyl peroxide occurs by a polar mechanism and that the hydrolysis is easy because there is no special stability associated with the seven-membered platinum-phthalate chelate ring.
    Organometallics 11/2012; 31(23):8291–8300. · 4.15 Impact Factor
  • Matthew S McCready, Richard J Puddephatt
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    ABSTRACT: The controlled synthesis of isomeric organoplatinum clamshell dimers [Pt(2)Me(2)(μ(2)-κ(3)-6-dppd)(2)](2+), 6-dppd = 1,4-di-2-pyridyl-5,6,7,8,9,10-hexahydrocycloocta[d]pyridazine, is reported. The new complexes are formed selectively by self-assembly from mononuclear precursors, taking advantage of the slow cis-trans isomerization at platinum(ii). Thus reaction of endo-[PtClMe(κ(2)-6-dppd)] with AgOTf gave endo,endo-[Pt(2)Me(2)(μ(2)-κ(3)-6-dppd)(2)](2+), while the reaction of [PtMe(2)(κ(2)-6-dppd)] with HOTf in solvent S = Me(2)C[double bond, length as m-dash]O or MeCN gave first a mixture of exo- and endo-[PtMe(S)(κ(2)-6-dppd)](+) and then, by loss of solvent, a mixture of exo,exo- and endo,endo-[Pt(2)Me(2)(μ(2)-κ(3)-6-dppd)(2)](2+). The endo,endo isomer slowly isomerized to the more stable exo,exo isomer in solution. Reaction of PPh(3) with endo-[PtClMe(κ(2)-6-dppd)] gave a mixture of endo- and exo-[PtMe(PPh(3))(κ(2)-6-dppd)](+) but reaction with exo,exo-[Pt(2)Me(2)(μ(2)-κ(3)-6-dppd)(2)](2+) gave exo-[PtMe(PPh(3))(κ(2)-6-dppd)](+) selectively, with retention of stereochemistry. The structures of the clamshell dimers and of key precursors are reported and equilibria are studied both experimentally and by DFT calculations.
    Dalton Transactions 08/2012; 41(40):12378-85. · 3.81 Impact Factor
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    ABSTRACT: A diimine ligand, LL = 2-C 5 H 4 NCHN-4-C 6 H 4 NNPh, which carries a trans-azobenzene substituent, forms the dimethylplatinum(II) complex [PtMe 2 (LL)], which undergoes trans oxidative addition with MeI, PhCH 2 Br, Br 2 , and I 2 to give the corresponding organoplatinum(IV) complexes [PtIMe 3 (LL)], [PtBrMe 2 (CH 2 Ph)(LL)], [PtBr 2 Me 2 (LL)], and [PtI 2 Me 2 (LL)], respectively. The ligand and the platinum(II) and platinum(IV) complexes are shown to undergo trans−cis isomerization of the azobenzene substituent upon irradiation, and the cis isomers then underwent slow thermal isomerization back to the more stable trans isomers. ■ INTRODUCTION The design and synthesis of organic materials that possess photoswitching ability has been the focus of considerable interest, because these molecular materials have potential applications in areas ranging from pharmaceuticals to optical data storage and photoswitching devices. 1−3 There are many photochromic molecules, including derivatives of spiropyrans, fulgides, diarylethenes, and stilbenes, 4−7 but azobenzenes have attracted particular interest because of their ease of synthesis, their high stability, and their UV−visible absorbance over a wide range of wavelengths. 8 Azobenzene normally exists as the trans isomer, which undergoes trans−cis isomerization upon irradiation with UV light, while the back process can be achieved either by heat or by irradiation with visible light. The trans−cis photoisomerization process is accompanied by a structural change in which the distance between para carbon atoms in azobenzene decreases from 9 to 5.5 Å (Scheme 1), and it is this structural change that can lead to a change in chemical or physical properties and forms the basis of the photoswitching ability. 8 The synthesis of transition-metal complexes with azo substituents has attracted interest in order to combine the remarkable photoswitching property of azobenzene with the magnetic, electrochemical, catalytic, or biological properties of the metal complex. 9 In many of the known complexes, the azo ligand is chelated to the metal through one of the nitrogen atoms and either a second nitrogen donor substituent or a carbon atom, so that photoisomerization of the azobenzene group is not possible. 9−11 Few transition-metal complexes, 12 and even fewer organometallic complexes, 13 are known in which the azo group is free to undergo photoisomerization. Some of these are illustrated in Chart 1, illustrating that the azo group can be incorporated either into the organometallic unit itself or into a supporting ligand.
  • Kyle R. Pellarin, Matthew S. McCready, Richard J. Puddephatt
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    ABSTRACT: The complexes [PtMe2(NN)] (NN = 2,2′-bipyridine = bipy, 1a; NN = di-2-pyridylamine = dpa, 1b; NN = di-2-pyridyl ketone = dpk, 1c) react with dimethyldioxirane in moist acetone to give the hydroxoplatinum(IV) complexes [Pt(OH)2Me2(NN)] (NN = bipy, 2a; NN = dpa, 2b, or [Pt(OH)Me2(dpkOH)], 3). Complex 2a crystallizes as the hydrate 2a·7H2O, which has a complex supramolecular network structure formed through hydrogen bonding between PtOH groups and water molecules. Attempts to trap a potential oxoplatinum(IV) intermediate in these reactions were unsuccessful, and computational studies suggest that oxoplatinum(IV) intermediates are improbable. It is suggested that oxygen atom transfer from the dioxirane to platinum is coupled to proton addition to give the hydroxoplatinum group directly.
    Organometallics 08/2012; 31(17):6388–6394. · 4.15 Impact Factor
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    ABSTRACT: Dimethylplatinum(II) complexes [PtMe2(NN)], with NN = diimine ligand, can react with dichloromethane or chloroform solvent to give the corresponding organoplatinum(IV) complexes [PtClMe2(CH2Cl)(NN)] or [PtClMe2(CHCl2)(NN)], respectively. The products can exist in isomeric forms, corresponding to products of cis or trans oxidative addition. The structures of three dichloromethane adducts and one chloroform adduct are reported.
    Canadian Journal of Chemistry 10/2011; 90(1):46-54. · 0.96 Impact Factor
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    Matthew S McCready, Richard J Puddephatt
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    ABSTRACT: The title complex, [Pt(CH(3))(2)(SCH(2)CH(2)CO(2))(C(10)H(8)N(2))], is formed by the unusual oxidative addition of the disulfide, R(2)S(2) (R = CH(2)CH(2)CO(2)H), to (2,2'-bipyridine)-dimethyl-platin-um(II) with elimination of RSH. The product contains an unusual six-membered thiol-ate-carboxyl-ate chelate ring. This slightly distorted octa-hedral complex exhibits cis angles ranging from 77.55 (11) to 97.30 (8)° due to the presence of the thiol-ate-carboxyl-ate chelate ring and the constrained bipyridine group. The crystal packing appears to be controlled by a combination of π-stacking [centroid-centroid distance = 3.611 (2) Å] and C-H⋯O inter-actions.
    Acta Crystallographica Section E Structure Reports Online 05/2011; 67(Pt 5):m604-5. · 0.35 Impact Factor
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    M.S. McCready, R.J. Puddephatt
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    ABSTRACT: The title complex, [Pt(CH3)2(SCH2CH2CO2)(C10H8N2)], is formed by the unusual oxidative addition of the disulfide, R2S2 (R = CH2CH2CO2H), to (2,2′-bipyridine)­dimethyl­platin­um(II) with elimination of RSH. The product contains an unusual six-membered thiol­ate–carboxyl­ate chelate ring. This slightly distorted octa­hedral complex exhibits cis angles ranging from 77.55 (11) to 97.30 (8)° due to the presence of the thiol­ate–carboxyl­ate chelate ring and the constrained bipyridine group. The crystal packing appears to be controlled by a combination of π-stacking [centroid–centroid distance = 3.611 (2) Å] and C—H⋯O inter­actions.
    Acta Crystallographica Section E Structure Reports Online 04/2011; 67(5). · 0.35 Impact Factor
  • Matthew S. McCready, Richard J. Puddephatt
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    ABSTRACT: An unusual type of oxidative addition of disulfides containing a carboxylic acid group to platinum(II) is established, giving the first thiolate–carboxylate complexes of platinum(IV). The disulfide R2S2 with R=CH2CH2CO2H reacts with [PtMe2(2,2′-bipyridine)] to give RSH and the chelating thiolate–carboxylate complex [PtMe2(κ2-S,O–SCH2CH2CO2)(bipy)]. However, the disulfide R2S2 with R=C6H3–4–NO2–3–CO2H reacts to give first the product of trans oxidative addition [PtMe2(SR)2(bipy)], which slowly reacts further to give RSH and the bridging thiolate–carboxylate complex [Pt2Me4(κ2–S,O–SC6H3–4–NO2–3–CO2)2(bipy)2].
    Inorganic Chemistry Communications - INORG CHEM COMMUN. 01/2011; 14(1):210-212.
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    ABSTRACT: The oxidative addition of iodine to [PtMe2(bipy)], 1, occurs easily with trans stereochemistry to give trans-[PtI2Me2(bipy)], 2a, which then equilibrates slowly with cis-[PtI2Me2(bipy)], 2b. The structures of 2a and 2b were determined in a crystal containing both isomers and an additional iodine molecule. Low temperature NMR studies show that an intermediate charge transfer complex [PtMe2(I2)(bipy)], 3, or solvated iodine complex [PtMe2(I2)(S)(bipy)], S = solvent, may be formed in dichloromethane or acetone solution before formation of 2a. In dilute benzene solution, as monitored by UV–visible spectroscopy, the rearrangement of the intermediate complex to 2a followed first order kinetics, and exhibited a large negative entropy of activation, as expected if cleavage of the I–I bond to give an ionic intermediate [PtIMe2(bipy)]+I−, is rate determining. The overall reaction is slower in more polar solvents because, although the I–I bond is more easily cleaved to give [PtIMe2(bipy)(S)]+I−, the subsequent displacement of solvent, S, by iodide to give 2a is slow.
    Journal of Organometallic Chemistry 713:60–67. · 2.00 Impact Factor