Philip P. Power

University of California, Davis, Davis, California, United States

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Publications (515)3186.73 Total impact

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    ABSTRACT: Mössbauer studies of three two-coordinate linear high-spin Fe(2+) compounds, namely, Fe{N(SiMe3)(Dipp)}2 (1) (Dipp = C6H3-2,6-(i)Pr2), Fe(OAr')2 (2) [Ar' = C6H3-2,6-(C6H3-2,6-(i)Pr2)2], and Fe{C(SiMe3)3}2 (3), are presented. The complexes were characterized by zero- and applied-field Mössbauer spectroscopy (1-3), as well as zero- and applied-field heat-capacity measurements (3). As 1-3 are rigorously linear, the distortion(s) that might normally be expected in view of the Jahn-Teller theorem need not necessarily apply. We find that the resulting very large unquenched orbital angular momentum leads to what we believe to be the largest observed internal magnetic field to date in a high-spin iron(II) compound, specifically +162 T in 1. The latter field is strongly polarized along the directions of the external field for both longitudinal and transverse field applications. For the longitudinal case, the applied field increases the overall hyperfine splitting consistent with a dominant orbital contribution to the effective internal field. By contrast, 2 has an internal field that is not as strongly polarized along a longitudinally applied field and is smaller in magnitude at ca. 116 T. Complex 3 behaves similarly to complex 1. They are sufficiently self-dilute (e.g., Fe···Fe distances of ca. 9-10 Å) to exhibit varying degrees of slow paramagnetic relaxation in zero field for the neat solid form. In the absence of EPR signals for 1-3, we show that heat-capacity measurements for one of the complexes (3) establish a geff value near 12, in agreement with the principal component of the ligand electric field gradient being coincident with the z axis.
    Inorganic Chemistry 11/2014; · 4.79 Impact Factor
  • Organometallics 10/2014; · 4.25 Impact Factor
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    ABSTRACT: Graphical abstract The terphenyl thiolato aluminates LiAl(SArMe6)2Br2·PhMe, LiAl(SArMe6)Br3 (ArMe6 = C6H3-2,6(C6H2-2,4,6-Me3)) and the neutral Al(SArPri4)Br2(OEt2) (ArPri4 = C6H3-2,6(C6H3-2,6-iPr2)2) were obtained by the reactions of the lithium thiolates with AlBr3. Their reduction with KC8 or Rieke’s magnesium afforded aluminum thiolates/hydrides or the incorporation of iodine in place of bromine but no Al–Al bond formation.
    Polyhedron 09/2014; 79:207–212. · 2.05 Impact Factor
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    ABSTRACT: Three potassium crown ether salts, [K(Et2O)2(18-crown-6)][Fe{N(SiMe3)Dipp}2] (1a; Dipp = C6H3-2,6-Pr(i)2), [K(18-crown-6)][Fe{N(SiMe3)Dipp}2]·0.5PhMe (1b), and [K(18-crown-6)][M{N(SiMe3)Dipp}2] (M = Co, 2; M = Ni, 3), of the two-coordinate linear or near-linear bis-amido monoanions [M{N(SiMe3)Dipp}2](-) (M = Fe, Co, Ni) were synthesized by one-electron reduction of the neutral precursors M{N(SiMe3)Dipp}2 with KC8 in the presence of 18-crown-6. They were characterized by X-ray crystallography, UV-vis spectroscopy, cyclic voltammetry, and magnetic measurements. The anions feature lengthened M-N bonds in comparison with their neutral precursors, with slightly bent coordination (N-Fe-N = ca. 172°) for the iron(I) complex, but linear coordination for the cobalt(I) and nickel(I) complexes. Fits of the temperature dependence of χMT of 1 and 2 reveal that the iron(I) and cobalt(I) complexes have large negative D zero-field splittings and a substantial orbital contribution to their magnetic moments with L = 2, whereas the nickel(I) complex has at most a small orbital contribution to its magnetic moment. The magnetic results have been used to propose an ordering of the 3d orbitals in each of the complexes.
    Inorganic Chemistry 08/2014; · 4.79 Impact Factor
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    ABSTRACT: Mono- and bis-terphenyl complexes of molybdenum and tungsten with general composition M2(Ar')(O2CR)3 and M2(Ar')2(O2CR)2, respectively (Ar' = terphenyl ligand), that contain carboxylate groups bridging the quadruply bonded metal atoms, have been prepared and structurally characterized. The new compounds stem from the reactions of the dimetal tetracarboxylates, M2(O2CR)4 (M = Mo, R = H, Me, CF3; M = W, R = CF3) with the lithium salts of the appropriate terphenyl groups (Ar' = ArXyl2, ArMes2, ArDipp2 and ArTrip2). Substitution of one bidentate carboxylate by a monodentate terphenyl forms a M-C σ bond and creates a coordination unsaturation at the other metal atom. Hence in M2(Ar')2(O2CR)2 complexes the two metal atoms have a low coordination number and an also low electron count (fourteen). The unsaturation seems to be compensated by a weak M-Carene interaction that implicates one of the aryl substituents of the terphenyl central aryl ring, as revealed by X-ray studies performed with some of these complexes. Notwithstanding, the long M-Carene distances of ca. 2.78 Å found in some of these complexes suggest that the flanking aryl ring, whose spatial distribution is imposed by the topology of the Ar' ligand, may simply provide steric protection to the low-coordinate metal centre.
    Journal of the American Chemical Society 05/2014; · 11.44 Impact Factor
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    ABSTRACT: The homoleptic cobalt(I) alkyl [Co{C(SiMe2Ph)3}]2 (1) was prepared by reacting CoCl2 with [Li{C(SiMe2Ph)3}(THF)] in a 1:2 ratio. Attempts to synthesize the corresponding iron(I) species led to the iron(II) salt [Li(THF)4][Fe2(μ-Cl)3{C(SiMe2Ph)3}2] (2). Both 1 and 2 were characterized by X-ray crystallography, UV–vis spectroscopy, and magnetic measurements. The structure of 1 consists of dimeric units in which each cobalt(I) ion is σ-bonded to the central carbon of the alkyl group −C(SiMe2Ph)3 and π-bonded to one of the phenyl rings of the −C(SiMe2Ph)3 ligand attached to the other cobalt(I) ion in the dimer. The structure of 2 features three chlorides bridging two iron(II) ions. Each iron(II) ion is also σ-bonded to the central carbon of a terminal −C(SiMe2Ph)3 anionic ligand. The magnetic properties of 1 reveal the presence of two independent cobalt(I) ions with S = 1 and a significant zero-field splitting of D = 38.0(2) cm–1. The magnetic properties of 2 reveal extensive antiferromagnetic exchange coupling with J = −149(4) cm–1 and a large second-order Zeeman contribution to its molar magnetic susceptibility. Formation of the alkyl 1 and the halide complex 2 under similar conditions is probably due in part to the fact that Co(II) is more readily reduced than Fe(II).
    Organometallics 04/2014; 33(8):1917–1920. · 4.25 Impact Factor
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    ABSTRACT: Reactions of the tetrylenes Ge(SAr(Me6))2 () (Ar(Me6) = C6H3-2,6(C6H2-2,4,6-Me3)2), and Sn(SAr(Me6))2 () with (Mo(CO)4(NBD) (NBD = bicyclo[2.2.1]hepta-2,5-diene) gave three new, unusual complexes [Mo(THF)(CO)3{Ge(SAr(Me6))2}] (), [Mo(THF)(CO)3{Ge(SAr(Me6))2}] () and [Mo(CO)4{Sn(SAr(Me6))2}] () which display no significant Ge/Sn-Mo bonding. Instead the ligands are coordinated to molybdenum in a bidentate fashion via the thiolato sulfurs.
    Chemical Communications 04/2014; · 6.38 Impact Factor
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    ABSTRACT: Two unique systems based on low-coordinate main group elements that activate P4 are shown to quantitatively release the phosphorus cage upon short exposure to UV light. This reactivity marks the first reversible reactivity of P4, and the germanium system can be cycled 5 times without appreciable loss in activity. Theoretical calculations reveal that the LUMO is antibonding with respect to the main group element–phosphorus bonds and bonding with respect to reforming the P4 tetrahedron, providing a rationale for this unprecedented activity, and suggesting that the process is tunable based on the substituents.
    Chemistry - A European Journal 03/2014; · 5.93 Impact Factor
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    ABSTRACT: Treatment of the cobalt(II) amide, [Co{N(SiMe3)2}2]2, with four equivalents of the sterically crowded terphenyl phenols, HOAr(Me6) (Ar(Me6) = C6H3-2,6(C6H2-2,4,6-Me3)2) or HOAr(iPr4) (Ar(iPr4) = C6H3-2,6(C6H3-2,6-Pr(i)2)2), produced the first well-characterized, monomeric two-coordinate cobalt(II) bisaryloxides, Co(OAr(Me6))2 (1) and Co(OAr(iPr4))2 (2a and 2b), as red solids in good yields with elimination of HN(SiMe3)2. The compounds were characterized by electronic spectroscopy, X-ray crystallography, and direct current magnetization measurements. The O-Co-O interligand angles in 2a and 2b are 180°, whereas the O-Co-O angle in 1 is bent at 130.12(8)° and its cobalt(II) ion has a highly distorted pseudotetrahedral geometry with close interactions to the ipso-carbons of the two flanking aryl rings. The Co-O distances in 1, 2a, and 2b are 1.858(2), 1.841(1), and 1.836(2) Å respectively. Structural refinement revealed that 1, 2a, and 2b have different fractional occupations of the cobalt site in their crystal structures: 1, 95.0%, 2a, 93.5%, and 2b, 84.6%. Correction of the magnetic data for the different cobalt(II) occupancies showed that the magnetization of 2a and 2b was virtually identical. The effective magnetic moments for 1, 2a, and 2b, 5.646(5), 5.754(5), and 5.636(3) μB respectively, were indicative of significant spin-orbit coupling. The differences in magnetic properties between 1 and 2a/2b are attributed to their different cobalt coordination geometries.
    Inorganic Chemistry 02/2014; · 4.79 Impact Factor
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    ABSTRACT: Treatment of toluene solutions of the silylenes Si(SArMe6)2 (ArMe6 = C6H3-2,6(C6H2-2,4,6-Me3), 1) or Si(SArPri4)2 (ArPri4 = C6H3-2,6(C6H3-2,6-Pri2), 2) with excess ethylene gas affords the siliranes (ArMe6S)2SiCH2CH2 (3) and (ArPri4S)2SiCH2CH2 (4). Silirane 4 evolves ethylene spontaneously at room temperature. A Van't Hoff analysis by variable temperature 1H NMR spectroscopy showed that ΔGassn is -24.9 (2.5) kJ mol-1 for 4. A computational study of the reaction mechanism using a model silylene Si(SPh)2 (Ph = C6H5) was in harmony with the Van't Hoff analysis and yields ΔGassn = -24 kJ mol-1 and an activation energy ΔG‡ of 54 kJ mol-1.
    Journal of the American Chemical Society 12/2013; · 11.44 Impact Factor
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    ABSTRACT: The synthesis and characterization of the sterically crowded primary alanes (AriPr4AlH2)2 (AriPr4 = C6H3-2,6(C6H3-2,6-iPr2)2) and (AriPr8AlH2)2 (AriPr8 = C6H-2,6(C6H2-2,4,6-iPr6)2-3,5-iPr2) are described. They, along with their previously reported less-hindered analogue (ArMe6AlH2)2 (ArMe6 = C6H3-2,6(C6H2-2,4,6-Me3)2), were reacted with ammonia to give the parent amido alanes {ArxAl(H)NH2}2 (Arx = ArMe6, 1; AriPr4, 2; AriPr8, 3), which are the first well-characterized hydride amido derivatives of aluminum and are relatively rare examples of parent aluminum amides. In contrast, the reaction of (ArMe6AlH2)2 with phosphine yielded the structurally unique Al/P cage species {(ArMe6Al)3(μ-PH2)3(μ-PH)PH2} (4) as the major product and a smaller amount of {(ArMe6Al)4(μ-PH2)4(μ-PH)} (5) as a minor product. All compounds were characterized by NMR and IR spectroscopy, while compounds 2–5 were also characterized by X-ray crystallography.
    Organometallics 12/2013; 33(1):329–337. · 4.25 Impact Factor
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    ABSTRACT: The reaction of phosphine gas with a low coordinate diaryl germylene or diarylstannylene results in both oxidative addition and arene elimination at the group 14 atom. The products were characterised by (31)P NMR spectroscopy and X-ray crystallography, and represent the first P-H bond activation by a heavy group 14 element compound.
    Chemical Communications 12/2013; · 6.38 Impact Factor
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    ABSTRACT: The titanium bisamido complex Ti{N(H)Ar(iPr6)}2 (Ar(iPr6) = C6H3-2,6-(C6H2-2,4,6-(i)Pr3)2 (2), along with its three-coordinate titanium(III) precursor, TiCl{N(H)Ar(iPr6)}2 (1), have been synthesized and characterized. Compound 1 was obtained via the stoichiometric reaction of LiN(H)Ar(iPr6) with the Ti(III) complex TiCl3·2NMe3 in trimethylamine. Reduction of 1 with 1 equiv of KC8 afforded Ti{N(H)Ar(iPr6)}2 (2) in moderate yield. Both 1 and 2 were characterized by X-ray crystallography, NMR, and IR spectroscopy, magnetic studies, and by density functional theory (DFT) computations. The precursor 1 has quasi-four-coordinate coordination at the titanium atom, with bonding to two amido nitrogens and a chlorine as well as a secondary interaction to a flanking aryl ring of a terphenyl substituent. Compound 2 displays a very distorted four-coordinate metal environment in which the titanium atom is bound to two amido nitrogens and to two carbons from a terphenyl aryl ring. This structure is in sharp contrast to the expected two-coordinate linear structure that was observed in its first row metal (V-Ni) analogues. Magnetic studies confirm a d(1) electron configuration for 1 but indicate that Ti{N(H)Ar(iPr6)}2 (2) is diamagnetic at ambient temperature consistent with the oxidation of titanium to Ti(IV). The different structure of 2 is attributed to the high reducing tendency of the Ti(II) in comparison to the other metals.
    Inorganic Chemistry 11/2013; · 4.79 Impact Factor
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    ABSTRACT: A series of high spin, two-coordinate first row transition metal-amido complexes, M{N(SiMe3)Dipp}2 {M = Fe (1), Co (2), or Ni (3); Dipp = C6H3-2,6-Pr(i)2} and a tetranuclear C-H activated chromium amide, [Cr{N(SiMe2CH2)Dipp}2Cr]2(THF) (4), were synthesized by reaction of their respective metal dihalides with 2 equiv of the lithium amide salt. They were characterized by X-ray crystallography, electronic and infrared spectroscopy, SQUID magnetic measurements, and computational methods. Contrary to steric considerations, the structures of 1-3 display planar eclipsed M{NSiC(ipso)}2 arrays and short M-N distances. DFT calculations, corrected for dispersion effects, show that dispersion interactions involving C-H-H-C moieties likely stabilize the structures by 21.1-29.4 kcal mol(-1), depending on the level of the calculations employed. SQUID measurements confirm high spin electron configurations for all the complexes and substantial orbital contributions for 1 and 2.
    Inorganic Chemistry 11/2013; · 4.79 Impact Factor
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    ABSTRACT: The synthesis, magnetic, and spectroscopic characteristics of the synthetically useful dimeric cobalt(II) silylamide complex [Co{N(SiMe3)2}2]2 (1) and several of its Lewis base complexes have been investigated. Variable-temperature nuclear magnetic resonance (NMR) spectroscopy of 1 showed that it exists in a monomer-dimer equilibrium in benzene solution and has an association energy (ΔGreacn) of -0.30(20) kcal mol(-1) at 300 K. Magnetic data for the polycrystalline, red-brown [Co{N(SiMe3)2}2]2 (1) showed that it displays strong antiferromagnetic exchange coupling, expressed as -2JexS1S2, between the two S = (3)/2 cobalt(II) centers with a Jex value of -215(5) cm(-1), which is consistent with its bridged dimeric structure in the solid state. The electronic spectrum of 1 in solution is reported for the first time, and it is shown that earlier reports of the melting point, synthesis, electronic spectrum, and magnetic studies of the monomer "Co{N(SiMe3)2}2" are consistent with those of the bright green-colored tetrahydrofuran (THF) complex [Co{N(SiMe3)2}2(THF)] (4). Treatment of 1 with various Lewis bases yielded monomeric three-coordinated species-[Co{N(SiMe3)2}2(PMe3)] (2), and [Co{N(SiMe3)2}2(THF)] (4), as well as the previously reported [Co{N(SiMe3)2}2(py)] (3)-and the four-coordinated species [Co{N(SiMe3)2}2(py)2] (5) in good yields. The paramagnetic complexes 2-4 were characterized by electronic and (1)H NMR spectroscopy, and by X-ray crystallography in the case of 2 and 4. Magnetic studies of 2-5 and of the known three-coordinated cobalt(II) species [Na(12-crown-4)2][Co{N(SiMe3)2}3] (6) showed that they have considerably larger χMT products and, hence, magnetic moments, than the spin-only values of 1.875 emu K mol(-1) and 3.87 μB, which is indicative of a significant zero-field splitting and g-tensor anisotropy resulting from the pseudo-trigonal crystal field. A fit of χMT for 2-6 yields a large g-tensor anisotropy, large negative D-values (between -62 cm(-1) and -82 cm(-1)), and E-values between ±10 cm(-1) and ±21 cm(-1).
    Inorganic Chemistry 10/2013; · 4.79 Impact Factor
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    ABSTRACT: A detailed computational investigation of orbital interactions in metal–carbon bonds of metallylene–isocyanide adducts of the type R2MCNR′ (M = Si, Ge, Sn; R, R′ = alkyl, aryl) was performed using density functional theory and different methods based on energy decomposition analysis. Similar analyses have not been carried out before for metal complexes of isocyanides, even though the related carbonyl complexes have been under intense investigations throughout the years. The results of our work reveal that the relative importance of π-type back-bonding interactions in these systems increases in the sequence Sn < Ge Si, and in contrast to some earlier assumptions, the π-component cannot be neglected for any of the systems investigated. While the fundamental ligand properties of isocyanides are very similar to those of carbonyl, there are significant variations in the magnitudes of different effects observed. Most notably, on coordination to metals, both ligands can display positive or negative shifts in their characteristic stretching frequencies. However, because isocyanides are stronger σ donors, the metal-induced changes in the CN bonding framework are greater than those observed for carbonyl. Consequently, isocyanides readily exhibit positive CN stretching frequency shifts even in complexes where they function as π-acceptors, and the sign of these shifts is alone a poor indicator of the nature of the metal–carbon interaction. On the other hand, the relative π-character of the metal–carbon bond in metallylene–isocyanide adducts, as judged by the natural orbitals of chemical valence as well as by partitions of the orbital interaction energy, was shown to have a linear correlation with the shift in CN stretching frequency upon complex formation. The details of this correlation show that π-back-donation contributions to total orbital interaction energy need to exceed 100 kJ mol–1 in order for the shift in the CN stretching frequency of metallylene–isocyanide adducts to be negative.
    Organometallics 08/2013; 32(22):6690–6700. · 4.25 Impact Factor
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    ABSTRACT: The synthesis and characterization of the first stable two-coordinate vanadium complexes are described. The vanadium(II) primary amido derivative V{N(H)AriPr6}2 [AriPr6 = C6H3-2,6-(C6H2-2,4,6-iPr3)2] (1) was synthesized via the reaction of LiN(H)AriPr6 with the V(III) complex VCl3·2NMe3 or the V(II) salt [V2Cl3(THF)6]+I– in a 2:1 and 4:1 stoichiometry, respectively. Reaction of the less crowded LiN(H)ArMe6 with [V2Cl3(THF)6]+I– afforded V{N(H)ArMe6}2 [ArMe6 = C6H3-2,6-(C6H2-2,4,6-Me3)2] (2), which has a nonlinear [N–V–N = 123.47(9)°] vanadium coordination. Magnetometry studies showed that V{N(H)AriPr6}2 and V{N(H)ArMe6}2 have ambient temperature magnetic moments of 3.41 and 2.77 μB, respectively, which are consistent with a high-spin d3 electron configuration. These values suggest a significant spin orbital angular momentum contribution that leads to a magnetic moment that is lower than their spin-only value of 3.87 μB. DFT calculations showed that the major absorptions in their UV–vis spectra were due to ligand to metal charge transfer transitions. Exposure of the reaction mixture for 2 to dry O2 resulted in the formation of the diamagnetic V(V) oxocluster [V{N(H)ArMe6}2]2(μ-O–Li–O)2 (3).
    Journal of the American Chemical Society 07/2013; 135(29):10720–10728. · 11.44 Impact Factor
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    ABSTRACT: The synthesis, spectroscopic and structural characterization of an extensive series of acyclic, monomeric tetrylene dichalcogenolates of formula M(ChAr)2 (M = Si, Ge, Sn, Pb; Ch = O, S, or Se; Ar = bulky m-terphenyl ligand, including two new acyclic silylenes) are described. They were found to possess several unusual features-the most notable of which is their strong tendency to display acute interligand, Ch-M-Ch, bond angles that are often well below 90°. Furthermore, and contrary to normal steric expectations, the interligand angles were found to become narrower as the size of the ligand was increased. Experimental and structural data in conjunction with high-level DFT calculations, including corrections for dispersion effects, led to the conclusion that dispersion forces play a key role in stabilizing their acute interligand angles.
    Journal of the American Chemical Society 05/2013; · 11.44 Impact Factor
  • Zachary D Brown, Philip P Power
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    ABSTRACT: The main themes of this review are the mechanisms of the reactions of germanium and tin analogues of carbenes with isocyanides, CO, ammonia, and related molecules. The treatment of Ge(Ar(Me6))2 (Ar(Me6) = C6H3-2,6(C6H2-2,4,6-Me3)2) with MeNC or Bu(t)NC afforded 1:1 complexes, but the increase in the electron density at germanium leads to C-H activation at the isocyanide methyl or tert-butyl substituents. For MeNC, the initial adduct formation is followed by a migratory insertion of the MeNC carbon into a Ge-C(ipso) bond of an aryl substituent. The addition of excess MeNC led to sequential insertions of two further MeNC molecules. The third insertion led to methylisocyanide methyl group C-H activation, to afford an azagermacyclopentadienyl species. The Bu(t)NC complex (Ar(Me6))2GeCNBu(t) spontanously transforms into (Ar(Me6))2Ge(H)CN and isobutene with C-H activation of the Bu(t) substituent. The germylene Ge(Ar(Me6))(Ar(Pr(i)4)) [Ar(Pr(i)4) = C6H3-2,6(C6H3-2,6-Pr(i)2)2] reacted with CO to afford α-germyloxyketones. The initial step is the formation of a 1:1 complex, followed by migratory insertion into the Ge-C bond of the Ar(Pr(i)4) ligand to give Ar(Me6)GeC(O)Ar(Pr(i)4). Insertion of a second CO gave Ar(Me6)GeC(O)C(O)Ar(Pr(i)4), which rearranges to afford α-germyloxyketone. No reaction was observed for Sn(Ar(Me6))2 with RNC (R = Me, Bu(t)) or CO. Spectroscopic (IR) results and density functional theory (DFT) calculations showed that the reactivity can be rationalized on the basis of Ge-C (isocyanide or CO) Ge(n) → π* (ligand) back-bonding. The reaction of Ge(Ar(Me6))2 and Sn(Ar(Me6))2 with ammonia or hydrazines initially gave 1:1 adducts. However, DFT calculations show that there are ancillary N-H---N interactions with a second ammonia or hydrazine, which stabilizes the transition state to form germanium(IV) hydride (amido or hydrazido) products. For tin, arene elimination is favored by a buildup of electron density at the tin, as well as the greater polarity of the Sn-C(ipso) bond. Germanium(IV) products were observed upon reaction of Ge(Ar(Me6))2 with acids, whereas reactions of Sn(Ar(Me6))2 with acids did not give tin(II) products. In contrast to reactions with NH3, there is no buildup of negative charge at tin upon protonation, and its subsequent reaction with conjugate bases readily affords the tin(IV) products.
    Inorganic Chemistry 05/2013; · 4.79 Impact Factor
  • Christine A. Caputo, Philip P. Power
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    ABSTRACT: The major theme of this review concerns the reaction pathways of heavier main group 13 dimetallenes with olefins, cyclic olefins, polyolefins, other unsaturated molecules, and hydrogen. For gallium derivatives, these reactions proceed readily in high yield under ambient conditions. Early investigations showed that the group 13 dimetallenes dissociated to one-coordinate metallanediyl monomers, which suggested that they reacted as monomeric species due to their more open, less hindered structures. However, recent DFT calculations by Tuononen and co-workers show that the reaction of the monomers with olefins or hydrogen involves very large energy barriers and that the dimetallenes react instead as undissociated dimers. In contrast to the corresponding all-carbon systems, where [2 + 2] cycloadditions are forbidden because of π–π* symmetry mismatch, the dimetallenes react with olefins via two stepwise, symmetry-allowed [2 + 2] cycloadditions to give 1,4-digallacyclohexanes. The addition of the H2 proceeds by a different mechanism, initially involving a 1,2-dihydride intermediate to ultimately yield two ArGaH2 molecules, which recombine to give Ar(H)Ga(μ-H)2Ga(H)Ar. The corresponding dialuminene is more highly reactive and reacts with solvent toluene to give an unusual [2 + 4] cycloaddition product. Calculations reveal that there is an enhanced diradical character in its bonding and that the reaction with propene affords an open-shell transition state involving a dangling CH3ĊHCH2Al moiety with unpaired spin density also on aluminum.
    Organometallics 04/2013; 32(8):2278–2286. · 4.25 Impact Factor

Publication Stats

8k Citations
3,186.73 Total Impact Points


  • 1987–2014
    • University of California, Davis
      • Department of Chemistry
      Davis, California, United States
  • 2011–2012
    • Nanjing University
      • Department of Chemical Engineering
      Nanjing, Jiangsu Sheng, China
    • Devi Ahilya University, Indore
      • School of Chemical Sciences
      Indore, State of Madhya Pradesh, India
  • 2010
    • Graz University of Technology
      Gratz, Styria, Austria
    • Universidad de Guanajuato
      Ciudad Guanajuato, Guanajuato, Mexico
  • 2005
    • Georg-August-Universität Göttingen
      • Institute of Inorganic Chemistry
      Göttingen, Lower Saxony, Germany
  • 2001
    • The University of Edinburgh
      • School of Chemistry
      Edinburgh, SCT, United Kingdom