Synthesis, electronic nature, and reactivity of selected silylene carbonyl complexes.

Room-temperature stable main group element carbonyl complexes are rare. Here we report on the synthesis of two such complexes, namely gallium-substituted silylene-carbonyl complexes [L(X)Ga]SiCO (X = I 2, Me 3; L = HC[C(Me)NDipp], Dipp = 2,6-PrCH) by reaction of three equivalents of LGa with IDippSiI (IDipp = 1,3-bis(2,6-PrCH)-imidazol-2-ylidene) or by salt elimination from [L(Br)Ga]SiCO with MeLi. Both silylene carbonyl complexes were spectroscopically characterized as well as with single crystal X-ray diffraction (sc-XRD), while their electronic nature and the specific influence of the Ga-substituents X was evaluated by quantum chemical computations.

Geminal C-Cl and Si-Cl bond activation of chloromethanes and chlorosilanes by gallanediyl LGa.

The activation of relatively inert E-X σ-bonds by low-valent main group metal complexes is receiving increasing interest. We here confirm the promising potential of gallanediyl LGa (L = HC[C(Me)N(Dip)], Dip = 2,6-i-PrCH) to activate E-Cl (E = C, Si) σ-bonds of group 14 element compounds. Equimolar reactions of LGa with chloromethanes and chlorosilanes EHCl (E = C, = 0-2; E = Si, = 0, 1) occurred with E-Cl bond insertion and formation of gallylmethanes and -silanes L(Cl)GaEHCl (E = C, = 2 (1), 1 (2), 0 (3); E = Si, = 1 (4)).

A silicon-carbonyl complex stable at room temperature.

Main-group-element compounds with energetically high-lying donor and low-lying acceptor orbitals are able to mimic chemical bonding motifs and reactivity patterns known in transition metal chemistry, including small-molecule activation and catalytic reactions. Monovalent group 13 compounds and divalent group 14 compounds, particularly silylenes, have been shown to be excellent candidates for this purpose. However, one of the most common reactions of transition metal complexes, the direct reaction with carbon monoxide and formation of room-temperature isolable carbonyl complexes, is virtually unknown in main-group-element chemistry.

Comprehensive Study on Reactions of Group 13 Diyls with Tetraorganodipentelanes.

LGa {L = HC[C(Me)N(2,6- iPrCH)]} reversibly reacts with EPh (E = Sb, Bi) in a temperature-dependent equilibrium reaction with insertion into the E-E bond and formation of LGa(EPh) (E = Sb 1, Bi 2). Analogous findings were observed in the reactions of LGa {L = (CH)NC[N(2,6- iPrCH)]} with ER (R = Ph, Et), yielding LGa(EPh) (E = Sb 3, Bi 4) and LGa(EEt) (E = Sb 5, Bi 6). 1-3 and 5 were isolated by fractional crystallization at low temperature, whereas 4 and 6 could not be isolated in their pure form even at low temperature.

The Mackay-Type Cluster [Cu Al ](Cp*) : Open-Shell 67-Electron Superatom with Emerging Metal-Like Electronic Structure.

The paramagnetic cluster [Cu Al ](Cp*) was obtained from the reaction of [CuMes] and [AlCp*] (Cp*=η -C Me ; Mes=mesityl). This all-hydrocarbon ligand-stabilized M magic atom-number cluster features a Mackay-type nested icosahedral structure. Its open-shell 67-electron superatom configuration is unique.

A General Pathway for the Synthesis of Gallastibenes containing Ga=Sb Double Bonds.

Reactions of three equivalents of LGa {L=HC[C(Me)N(2,6-iPr C H )] } with SbX (X=F, Cl, Br, I) proceed with insertion into the Sb-X bond, elimination of LGaX , and formation of LGaSbGa(X)L (X=F 1, Cl 2, Br 3, I 4) containing a Ga=Sb double bond. In contrast, the 2:1 molar ratio reaction of LGa and SbCl initially gives the twofold insertion product [L(Cl)Ga] SbCl 7, which could not be isolated due to its strong tendency toward elimination of LGaCl and formation of distibene [L(Cl)GaSb] 5 at 25 °C or cyclotristibine [L(Cl)GaSb] 6 at 8 °C. The formation of 1-6 can be rationalized by formation of the Ga-substituted stibinidene L(X)GaSb as reaction intermediate.

From stable Sb- and Bi-centered radicals to a compound with a Ga=Sb double bond.

Neutral stibinyl and bismuthinyl radicals are typically short-lived, reactive species. Here we show the synthesis and solid-state structures of two stable stibinyl [L(Cl)Ga]Sb· 1 and bismuthinyl radicals [L(I)Ga]Bi· 4, which are stabilized by electropositive metal centers. Their description as predominantly metal-centered radicals is consistent with the results of NMR, EPR, SQUID, and DFT studies.

Synthesis, Structure, and Reactivity of Ga-Substituted Distibenes and Sb-Analogues of Bicyclo[1.1.0]butane.

Monovalent gallanediyl LGa {L=HC[C(Me)N(2,6-iPr C H )] } reacts with SbX to form the Ga-substituted distibenes [(LGaX) Sb ] (X=NMeEt 1, Cl 2). Upon heating, 2 reacts to the bicyclo[1.1.

Reduction of [Cp*Sb] with Subvalent Main-Group Metal Reductants: Syntheses and Structures of [(L Mg) (Sb )] and [(L Ga) (Sb )] Containing Edge-Missing Sb Units.

[Cp*Sb] (Cp*=C Me ) reacts with [L Mg] and L Ga with formation of [(L Mg) (μ ,η -Sb )] (L =iPr NC[N(2,6-iPr C H )] , 1) and [(L Ga) (μ,η -Sb )] (L =HC[C(Me)N(2,6-iPr C H )] , 2). The cleavage of the Sb-Sb and Sb-C bonds in [Cp*Sb] are the crucial steps in both reactions. The formation of 1 occurred by elimination of the Cp* anion and formation of Cp*MgL , while 2 was formed by reductive elimination of Cp* and oxidative addition of L Ga to the Sb unit.

Synthesis and Structural Characterization of Magnesium-Substituted Polystibides [(LMg)4Sb8 ].

Redox reactions of [(L(1,2) Mg)2 ] and Sb2 R4 (R=Me, Et) yielded the first Mg-substituted realgar-type Sb8 polystibides [(L(1,2) Mg)4 (μ4 ,η(2:2:2:2) -Sb8)] (L(1) =HC[C(Me)N(2,4,6-Me3 C6 H2)]2, L(2) =HC[C(Me)N(2,6-i-Pr2 C6 H3)]2). Compounds [(L(1,2) Mg)2] serve both as reducing agents, initiating the cleavage of the Sb-C bonds, and as stabilizers for the resulting Sb8 polyanion. The polystibides were characterized by NMR and IR spectroscopies, elemental analysis, and X-ray structure analysis.

A Gallium-Substituted Distibene and an Antimony-Analogue Bicyclo[1.1.0]butane: Synthesis and Solid-State Structures.

RGa {R=HC[C(Me)N(2,6-iPr2C6H3)]2} reacts with Sb(NMe2)3 with insertion into the Sb-N bond and elimination of RGa(NMe2)2 (2), yielding the Ga-substituted distibene R(Me2N)GaSb=SbGa(NMe2 )R (1). Thermolysis of 1 proceeded with elimination of RGa and 2 and subsequent formation of the bicyclo[1.1.

Te-Te and Te-C bond cleavage reactions using a monovalent gallanediyl.

LGa (L = [(2,6-i-Pr2-C6H3)NC(Me)]2CH) reacts with elemental tellurium with formation of the Te-bridged compound [LGa-μ-Te]2 1, whereas the reactions with Ph2Te2 and i-Pr2Te occurred with cleavage of the Te-Te and Te-C bond, respectively, and subsequent formation of LGa(TePh)2 2 and LGa(i-Pr)Tei-Pr 3. 1-3 were characterized by heteronuclear NMR ((1)H, (13)C, (125)Te) and IR spectroscopy and their solid state structures were determined by single crystal X-ray analyses.

Temperature-dependent electron shuffle in molecular Group 13/15 intermetallic complexes.

Monovalent RAl (R=HC[C(Me)N(2,6-iPr2C6H3)]2) reacts with E2Et4 (E=Sb, Bi) with insertion into the weak E-E bond and subsequent formation of RAl(EEt2)2 (E=Sb 1; Bi 2). The analogous reactions of RGa with E2Et4 yield a temperature-dependent equilibrium between RGa(EEt2)2 (E=Sb 3; Bi 4) and the starting reagents. RIn does not interact with Sb2Et4 under various reaction conditions, but formation of RIn(BiEt2)2 (5) was observed in the reaction with Bi2Et4 at low temperature.

The intermetalloid cluster [(Cp*AlCu)6H4], embedding a Cu6 core inside an octahedral Al6 shell: molecular models of Hume-Rothery nanophases.

Defined molecular models for the surface chemistry of Hume-Rothery nanophases related to catalysis are very rare. The Al-Cu intermetalloid cluster [(Cp*AlCu)6H4] was selectively obtained from the clean reaction of [(Cp*Al)4] and [(Ph3PCuH)6]. The stronger affinity of Cp*Al towards Cu sweeps the phosphine ligands from the copper hydride precursor and furnishes an octahedral Al6 cage to encapsulate the Cu6 core.

Cp* as a removable protecting group: low valent Zn(I) compounds by reductive elimination, protolytic and oxidative cleavage of Zn-Cp*.

Zn-Cp* bond cleavage reactions leading to novel monovalent cationic zinc species are presented (Cp* = pentamethylcyclopentadienyl). The treatment of [Zn2Cp*2] with two equiv. of [H(Et2O)2][BAr4(F)] (BAr4(F) = B{C6H3(CF3)2}4) yields the triple-decker complex [Cp*3Zn4(Et2O)2][BAr4(F)] (1) via protolytic removal of a Cp* ligand as Cp*H, whereas the reaction with an equimolar amount of [FeCp2][BAr4(F)] (Cp = cyclopentadienyl) results in the formation of [Cp*Zn2(Et2O)3][BAr4(F)] (2) under oxidative cleavage of a Cp* ring giving decamethylfulvalene, (Cp*)2, and [FeCp2] as by-products.

catena-Poly[[(tetrahydrofuran-κO)potassium]-μ-(η5:η5)-2,3,4,5-tetramethyl-1-n-pentylcyclopentadienyl].

The title compound, [K(C14H23)(C4H8O)]n, comprises zigzag chains of alternating bridging 2,3,4,5-tetramethyl-1-n-pentylcyclopentadienyl ligands and potassium ions, with an ancillary tetrahydrofuran ligand in the coordination environment of potassium. The coordination polymer strands so formed extend by 21 screw symmetry in the b-axis direction. The chemically modified cyclopentadienyl ligand, with a tethered n-pentyl group, was synthesized from 2,3,4,5-tetramethylcyclopent-2-enone by a Grignard reaction.

Reductive elimination: a pathway to low-valent aluminium species.

Compounds Cp*AlH2 (1) and Cp*2AlH (2) reductively eliminate Cp*H in benzene or toluene under reflux conditions to give Al(s) and AlCp*, respectively.

New hexaphosphane ligands 1,3,5-C6H3{p-C6H4N(PX2)2}3 [X = Cl, F, C6H3OMe(C3H5)]: synthesis, derivatization and palladium(II) and platinum(II) complexes.

A novel dodecachlorohexaphosphane, 1,3,5-C(6)H(3)[p-C(6)H(4)N(PCl(2))(2)](3) (1) was synthesized by reacting 1,3,5-tris(4'-anilino)benzene with phosphorus trichloride. Fluorination of 1 with SbF(3) produces 1,3,5-C(6)H(3)[p-C(6)H(4)N(PF(2))(2)](3) (2). The derivatization of chlorohexaphosphane with an aryloxy substituent and its palladium(II) and platinum(II) complexes are also described.

Unraveling the roles of the acid medium, experimental probes, and terminal oxidant, (NH4)2[Ce(NO3)6], in the study of a homogeneous water oxidation catalyst.

The oxidation of water catalyzed by [Ru(tpy)(bpy)(OH(2))](ClO(4))(2) (1; tpy = 2,2';6'',2''-terpyridine; bpy = 2,2'-bipyridine) is evaluated in different acidic media at variable oxidant concentrations. The observed rate of dioxygen evolution catalyzed by 1 is found to be highly dependent on pH and the identity of the acid; e.g.

Electrochemical evidence for catalytic water oxidation mediated by a high-valent cobalt complex.

The pH-dependent electrochemical behavior for a Co(II) complex, [Co(Py5)(OH(2))](ClO(4))(2) (1; Py5 = 2,6-(bis(bis-2-pyridyl)methoxymethane)pyridine), indicates consecutive (proton-coupled) oxidation steps furnish a Co(IV) species that catalyzes the oxidation of water in basic media.

Electronic modification of the [Ru(II)(tpy)(bpy)(OH(2))](2+) scaffold: effects on catalytic water oxidation.

The mechanistic details of the Ce(IV)-driven oxidation of water mediated by a series of structurally related catalysts formulated as [Ru(tpy)(L)(OH(2))](2+) [L = 2,2'-bipyridine (bpy), 1; 4,4'-dimethoxy-2,2'-bipyridine (bpy-OMe), 2; 4,4'-dicarboxy-2,2'-bipyridine (bpy-CO(2)H), 3; tpy = 2,2';6'',2''-terpyridine] is reported. Cyclic voltammetry shows that each of these complexes undergo three successive (proton-coupled) electron-transfer reactions to generate the [Ru(V)(tpy)(L)O](3+) ([Ru(V)=O](3+)) motif; the relative positions of each of these redox couples reflects the nature of the electron-donating or withdrawing character of the substituents on the bpy ligands. The first two (proton-coupled) electron-transfer reaction steps (k(1) and k(2)) were determined by stopped-flow spectroscopic techniques to be faster for 3 than 1 and 2.

Insight into water oxidation by mononuclear polypyridyl Ru catalysts.

A family of compounds based on the mononuclear coordination complex [Ru(tpy)(bpy)(OH(2))](2+) (1b; tpy = 2,2':6',2''-terpyridine, bpy = 2,2'-bipyridine) are shown to be competent catalysts in the Ce(IV)-driven oxidation of water in acidic media. The systematic installation of electron-withdrawing (e.g.

Weak interactions between trivalent pnictogen centers: computational analysis of bonding in dimers X3E...EX3 (E = pnictogen, X = halogen).

The nature of weak interactions in dimers X(3)E...

Group 11 metal chemistry of a tetradentate ligand, phenylene-1,4-diaminotetra(phosphonite), p-C6H4[N{P(OC6H4OMe-o)2}2]2.

The Cu(I), Ag(I), and Au(I) chemistry of a tetradentate ligand (phenylene-1,4-diaminotetra(phosphonite), p-C(6)H(4)[N{P(OC(6)H(4)OMe-o)(2)}(2)](2) (P(2)NPhiNP(2)) (1)) is described. The flexional conformations in 1 leads to interesting structural variations in transition-metal complexes. The reaction of 1 with 4 equiv of CuX (where X = Br and I) produce the tetranuclear complexes, [{Cu(2)(mu-X)(2)(NCCH(3))(2)}(2)(mu-P(2)NPhiNP(2))] (where X = Br (2) or X = I (3)) in quantitative yield.

Di-, tetra- and polynuclear RhI complexes containing phenylene-1,4-diaminotetra (phosphonite), p-C6H4[N{P(OC6H4OMe-o)2}2]2 and their catalytic investigation towards transfer hydrogenation reactions.

The reactions of phenylene-1,4-diaminotetra(phosphonite), p-C(6)H(4)[N{P(OC(6)H(4)OMe-o)(2)}(2)](2) (P(2)N(Ph)NP(2)) () with [Rh(COD)Cl](2) in 1 : 2 and 1 : 1 molar ratio produce tetra- and polymetallic chelate complexes, [Rh(4)(COD)(2)(micro-Cl)(4)(P(2)N(Ph)NP(2))] () and [Rh(2)(micro-Cl)(2)(P(2)N(Ph)NP(2))](n) (), respectively. Similar reaction of with [Rh(COD)Cl](2) in dichloromethane-acetonitrile mixture furnishes a dinuclear complex, [Rh(2)Cl(2)(CH(3)CN)(2)(P(2)N(Ph)NP(2))] (). The reaction of or with CO affords a dinuclear carbonyl derivative, [Rh(2)Cl(2)(CO)(2)(P(2)N(Ph)NP(2))] ().