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1.
Dalton Trans ; 51(21): 8249-8257, 2022 May 31.
Artigo em Inglês | MEDLINE | ID: mdl-35579035

RESUMO

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]2SiCO (X = I 2, Me 3; L = HC[C(Me)NDipp]2, Dipp = 2,6-iPr2C6H3) by reaction of three equivalents of LGa with IDippSiI4 (IDipp = 1,3-bis(2,6-iPr2C6H3)-imidazol-2-ylidene) or by salt elimination from [L(Br)Ga]2SiCO 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. In addition, we report the oxidative addition reaction of [L(Br)Ga]2SiCO with NH3, yielding [L(Br)Ga]2Si(H)NH24, demonstrating the promising potential of such complexes for small molecule activation.

2.
Dalton Trans ; 51(5): 2050-2058, 2022 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-35040458

RESUMO

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)]2, Dip = 2,6-i-Pr2C6H3) to activate E-Cl (E = C, Si) σ-bonds of group 14 element compounds. Equimolar reactions of LGa with chloromethanes and chlorosilanes EHxCl4-x (E = C, x = 0-2; E = Si, x = 0, 1) occurred with E-Cl bond insertion and formation of gallylmethanes and -silanes L(Cl)GaEHxCl3-x (E = C, x = 2 (1), 1 (2), 0 (3); E = Si, x = 1 (4)). In contrast, consecutive insertion into a geminal E-Cl bond was observed with two equivalents of LGa, yielding digallyl complexes [L(Cl)Ga]2EHxCl2-x (E = C, x = 2 (5); E = Si, x = 1 (6), 0 (7)). Compounds 1-7 were characterized by heteronuclear NMR (1H, 13C, 29Si (4, 6)), IR spectroscopy and elemental analysis, and their solid-state structures were determined by single-crystal X-ray diffraction (sc-XRD).

3.
Nat Chem ; 12(7): 608-614, 2020 07.
Artigo em Inglês | MEDLINE | ID: mdl-32313239

RESUMO

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. Here, we show the synthesis, single-crystal X-ray structure, and density functional theory computations of a room-temperature-stable silylene carbonyl complex [L(Br)Ga]2Si:-CO (L = HC[C(Me)N(2,6-iPr2-C6H3)]2), which was obtained by direct carbonylation of the electron-rich silylene intermediate [L(Br)Ga]2Si:. Furthermore, [L(Br)Ga]2Si:-CO reacts with H2 and PBr3 with bond activation, whereas the reaction with cyclohexyl isocyanide proceeds with CO substitution.

4.
Angew Chem Int Ed Engl ; 57(44): 14630-14634, 2018 Oct 26.
Artigo em Inglês | MEDLINE | ID: mdl-29981271

RESUMO

The paramagnetic cluster [Cu43 Al12 ](Cp*)12 was obtained from the reaction of [CuMes]5 and [AlCp*]4 (Cp*=η5 -C5 Me5 ; Mes=mesityl). This all-hydrocarbon ligand-stabilized M55 magic atom-number cluster features a Mackay-type nested icosahedral structure. Its open-shell 67-electron superatom configuration is unique. Three unpaired electrons occupy weakly antibonding jellium states. The situation prefigures the formation of a conduction band, which is in line with the measured temperature-independent magnetism. Steric protection by twelve Cp* ligands suppresses the intrinsic polyradicalar reactivity of the Cu43 Al12 core.

5.
Inorg Chem ; 57(15): 9495-9503, 2018 Aug 06.
Artigo em Inglês | MEDLINE | ID: mdl-30039963

RESUMO

L1Ga {L1 = HC[C(Me)N(2,6- iPr2C6H3)]2} reversibly reacts with E2Ph4 (E = Sb, Bi) in a temperature-dependent equilibrium reaction with insertion into the E-E bond and formation of L1Ga(EPh2)2 (E = Sb 1, Bi 2). Analogous findings were observed in the reactions of L2Ga {L2 = (C6H11)2NC[N(2,6- iPr2C6H3)]2} with E2R4 (R = Ph, Et), yielding L2Ga(EPh2)2 (E = Sb 3, Bi 4) and L2Ga(EEt2)2 (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. In contrast, reactions of [Cp*Al]4 (Cp* = C5Me5) with Sb2R4 (R = Ph, Et) and Bi2Et4 did not proceed with insertion into the E-E bonds but with formation of (Cp*Al)3E2 (E = Sb, 7; Bi, 8), whereas the reaction with Bi2Ph4 yielded metallic bismuth. 8 was also formed in the reaction of [Cp*Al]4 and BiEt3 at ambient temperature, whereas the analogous reaction of [Cp*Al]4 with SbEt3 did not yield 7 even under drastic reaction conditions (120 °C, 3 days). In contrast, Cp*Ga and Sb2R4 (R = Ph, Et) were found to react only at elevated temperature (120 °C) with formation of antimony metal.

6.
Chemistry ; 24(36): 9157-9164, 2018 Jun 26.
Artigo em Inglês | MEDLINE | ID: mdl-29665160

RESUMO

Reactions of three equivalents of LGa {L=HC[C(Me)N(2,6-iPr2 C6 H3 )]2 } with SbX3 (X=F, Cl, Br, I) proceed with insertion into the Sb-X bond, elimination of LGaX2 , 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 SbCl3 initially gives the twofold insertion product [L(Cl)Ga]2 SbCl 7, which could not be isolated due to its strong tendency toward elimination of LGaCl2 and formation of distibene [L(Cl)GaSb]2 5 at 25 °C or cyclotristibine [L(Cl)GaSb]3 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.

7.
Nat Commun ; 9(1): 87, 2018 01 08.
Artigo em Inglês | MEDLINE | ID: mdl-29311607

RESUMO

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]2Sb· 1 and bismuthinyl radicals [L(I)Ga]2Bi· 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. The Lewis-acidic character of the Ga ligands allow for significant electron delocalization of the Sb- and Bi- unpaired radical onto the ligand. Single-electron reduction of [L(Cl)Ga]2Sb· gave LGaSbGa(Cl)L 5, the first compound containing a Ga=Sb double bond. The π-bonding contribution is estimated to 9.56 kcal mol-1 by NMR spectroscopy. The bonding situation and electronic structure is analyzed by quantum mechanical computations, revealing significant π backdonation from the Sb to the Ga atom. The formation of 5 illustrates the high-synthetic potential of 1 for the formation of new compounds with unusual electronic structures.

8.
Chemistry ; 23(50): 12297-12304, 2017 Sep 07.
Artigo em Inglês | MEDLINE | ID: mdl-28497647

RESUMO

Monovalent gallanediyl LGa {L=HC[C(Me)N(2,6-iPr2 C6 H3 )]2 } reacts with SbX3 to form the Ga-substituted distibenes [(LGaX)2 Sb2 ] (X=NMeEt 1, Cl 2). Upon heating, 2 reacts to the bicyclo[1.1.0]butane analogue [(LGaCl)2 (µ,η1:1 -Sb4 )] 3 containing a [Sb4 ]2- dianion. Moreover, 2 reacts with Li amides LiNR2 in salt elimination reactions that form the corresponding amido-substituted compounds 1 and [(LGaNMe2 )2 Sb2 ] 4, whereas reactions of 4 and [(LGaNMe2 )2 (µ,η1:1 -Sb4 )] 5 with two equivalents of GaCl3 resulted in the formation of 2 and 3, respectively. 1, 2 and 3 were characterized by 1 H and 13 C NMR spectroscopy, elemental analysis, and single crystal X-ray diffraction. In addition, their bonding situation was analyzed by quantum chemical calculations.

9.
Chemistry ; 23(10): 2461-2468, 2017 Feb 16.
Artigo em Inglês | MEDLINE | ID: mdl-27921335

RESUMO

[Cp*Sb]4 (Cp*=C5 Me5 ) reacts with [L1 Mg]2 and L2 Ga with formation of [(L1 Mg)4 (µ4 ,η1:2:2:2 -Sb4 )] (L1 =iPr2 NC[N(2,6-iPr2 C6 H3 )]2 , 1) and [(L2 Ga)2 (µ,η2:2 -Sb4 )] (L2 =HC[C(Me)N(2,6-iPr2 C6 H3 )]2 , 2). The cleavage of the Sb-Sb and Sb-C bonds in [Cp*Sb]4 are the crucial steps in both reactions. The formation of 1 occurred by elimination of the Cp* anion and formation of Cp*MgL1 , while 2 was formed by reductive elimination of Cp*2 and oxidative addition of L2 Ga to the Sb4 unit. 1 and 2 were characterized by heteronuclear NMR spectroscopy and single-crystal X-ray diffraction, and their bonding situation was studied by quantum chemical calculations.

10.
Angew Chem Int Ed Engl ; 55(13): 4204-9, 2016 Mar 18.
Artigo em Inglês | MEDLINE | ID: mdl-26924273

RESUMO

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. In addition, results from quantum chemical calculations are presented.

11.
Angew Chem Int Ed Engl ; 54(36): 10657-61, 2015 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-26248643

RESUMO

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[1.1.0]butane analogue [R(Me2N)Ga]2Sb4 (3).

12.
Dalton Trans ; 44(11): 5153-9, 2015 Mar 21.
Artigo em Inglês | MEDLINE | ID: mdl-25680084

RESUMO

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.

13.
Angew Chem Int Ed Engl ; 53(43): 11587-91, 2014 Oct 20.
Artigo em Inglês | MEDLINE | ID: mdl-25196650

RESUMO

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.

14.
Angew Chem Int Ed Engl ; 53(30): 7943-7, 2014 Jul 21.
Artigo em Inglês | MEDLINE | ID: mdl-24962074

RESUMO

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. The resulting hydrido cluster M12H4 reacts with benzonitrile to give the stoichiometric hydrometalation product [(Cp*AlCu)6H3(N=CHPh)].

15.
Acta Crystallogr C ; 69(Pt 6): 573-6, 2013 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-23744369

RESUMO

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.

16.
Dalton Trans ; 42(29): 10540-4, 2013 Aug 07.
Artigo em Inglês | MEDLINE | ID: mdl-23760459

RESUMO

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. The molecular structures of compounds 1 and 2 are established by single-crystal X-ray diffraction studies. A new synthetic pathway for the formation of [Zn2Cp*2] based on the reductive elimination of Cp*H from in situ formed Cp*ZnH is presented.

17.
Chem Commun (Camb) ; 49(28): 2858-60, 2013 Apr 11.
Artigo em Inglês | MEDLINE | ID: mdl-23381663

RESUMO

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.

18.
Dalton Trans ; 40(22): 5841-3, 2011 Jun 14.
Artigo em Inglês | MEDLINE | ID: mdl-21552610

RESUMO

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.

19.
Chem Commun (Camb) ; 47(14): 4249-51, 2011 Apr 14.
Artigo em Inglês | MEDLINE | ID: mdl-21359324

RESUMO

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.

20.
Inorg Chem ; 50(8): 3662-72, 2011 Apr 18.
Artigo em Inglês | MEDLINE | ID: mdl-21413748

RESUMO

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., d[O(2)]/dt is progressively faster in H(2)SO(4), CF(3)SO(3)H (HOTf), HClO(4), and HNO(3), respectively. This trend does not track with thermodynamic driving force of the electron-transfer reactions between the terminal oxidant, (NH(4))(2)[Ce(NO(3))(6)] (CAN), and Ru catalyst in each of the acids. The particularly high reactivity in HNO(3) is attributed to the NO(3)(-) anion: (i) enabling relatively fast electron-transfer steps; (ii) participating in a base-assisted concerted atom-proton transfer process that circumvents the formation of high energy intermediates during the O-O bond formation process; and (iii) accelerating the liberation of dioxygen from the catalyst. Consequently, the position of the rate-determining step within the catalytic cycle can be affected by the acid medium. These factors collectively contribute to the position of the rate-determining step within the catalytic cycle being affected by the acid medium. This offering also outlines how other experimental issues (e.g., spontaneous decay of the Ce(IV) species in acidic media; CAN/catalyst molar ratio; types of catalytic probes) can affect the Ce(IV)-driven oxidation of water catalyzed by homogeneous molecular complexes.

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