A novel concept for the synthesis of multiply doped gold clusters [(M@Au(n)M'(m))L(k)](q+).

Heterometal-doped gold clusters are poorly accessible through wet-chemical approaches and main-group-metal- or early-transition-metal-doped gold clusters are rare. Compounds [M(AuPMe3 )11 (AuCl)](3+) (M=Pt, Pd, Ni) (1-3), [Ni(AuPPh3 )(8-2n) (AuCl)3 (AlCp*)n ] (n=1, 2) (4, 5), and [Mo(AuPMe3 )8 (GaCl2 )3 (GaCl)](+) (6) were selectively obtained by the transmetalation of [M(M'Cp*)n ] (M=Mo, E=Ga, n=6; M=Pt, Pd, Ni, M'=Ga, Al, n=4) with [ClAuPR3 ] (R=Me, Ph) and characterized by single-crystal X-ray diffraction and ESI mass spectrometry. DFT calculations were used to analyze the bonding situation. The transmetalation proved to be a powerful tool for the synthesis of heterometal-doped gold clusters with a design rule based on the 18 valence electron count for the central metal atom M and in agreement with the unified superatom concept based on the jellium model.

Oligonuclear molecular models of intermetallic phases: a case study on [Pd2Zn6Ga2(Cp*)5(CH3)3].

The synthesis, characterization, and theoretical investigation by means of quantum-chemical calculations of an oligonuclear metal-rich compound are presented. The reaction of homoleptic dinuclear palladium compound [Pd(2)(µ-GaCp*)(3)(GaCp*)(2)] with ZnMe(2) resulted in the formation of unprecedented ternary Pd/Ga/Zn compound [Pd(2)Zn(6)Ga(2)(Cp*)(5)(CH(3))(3)] (1), which was analyzed by (1)H and (13)C NMR spectroscopy, MS, elemental analysis, and single-crystal X-ray diffraction. Compound 1 consisted of two C(s)-symmetric molecular isomers, as revealed by NMR spectroscopy, at which distinct site-preferences related to the Ga and Zn positions were observed by quantum-chemical calculations. Structural characterization of compound 1 showed significantly different coordination environments for both palladium centers. Whilst one Pd atom sat in the central of a bi-capped trigonal prism, thereby resulting in a formal 18-valence electron fragment, {Pd(ZnMe)(2)(ZnCp*)(4)(GaMe)}, the other Pd atom occupied one capping unit, thereby resulting in a highly unsaturated 12-valence electron fragment, {Pd(GaCp*)}. The bonding situation, as determined by atoms-in-molecules analysis (AIM), NBO partial charges, and molecular orbital (MO) analysis, pointed out that significant Pd-Pd interactions had a large stake in the stabilization of this unusual molecule. The characterization and quantum-chemical calculations of compound 1 revealed distinct similarities to related M/Zn/Ga Hume-Rothery intermetallic solid-state compounds, such as Ga/Zn-exchange reactions, the site-preferences of the Zn/Ga positions, and direct M-M bonding, which contributes to the overall stability of the metal-rich compound.

Homoleptic hexa and penta gallylene coordinated complexes of molybdenum and rhodium.

The reactions of molybdenum(0) and rhodium(I) olefin containing starting materials with the carbenoid group 13 metal ligator ligand GaR (R = Cp*, DDP; Cp* = pentamethylcyclopentadienyl, DDP = HC(CMeNC(6)H(3)-2,6-(i)Pr(2))(2)) were investigated and compared. Treatment of [Mo(η(4)-butadiene)(3)] with GaCp* under hydrogen atmosphere at 100 °C yields the homoleptic, hexa coordinated, and sterically crowded complex [Mo(GaCp*)(6)] (1) in good yields ≥50%. Compound 1 exhibits an unusual and high coordinated octahedral [MoGa(6)] core. Similarly, [Rh(GaCp*)(5)][CF(3)SO(3)] (2) and [Rh(GaCp*)(5)][BAr(F)] (3) (BAr(F) = B{C(6)H(3)(CF(3))(2)}(4)) are prepared by the reaction of GaCp* with the rhodium(I) compound [Rh(coe)(2)(CF(3)SO(3))](2) (coe = cyclooctene) and subsequent anion exchange in case of 3. Compound 2 features a trigonal bipyramidal [RhGa(5)] unit. In contrast, reaction of excess Ga(DDP) with [Rh(coe)(2)(CF(3)SO(3))](2) does not result in a high coordinated homoleptic complex but instead yields [(coe)(toluene)Rh{Ga(DDP)}(CF(3)SO(3))] (4). The common feature of 2 and 4 in the solid state structure is the presence of short CF(3)SO(2)O···Ga contacts involving the GaCp* or rather the Ga(DDP) ligand. Compounds 1, 2, and 4 have been fully characterized by single crystal X-ray diffraction, variable temperature (1)H and (13)C NMR spectroscopy, IR spectroscopy, mass spectrometry, as well as elemental analysis.

The rich chemistry of [Zn2Cp*2]: trapping three different types of zinc ligands in the PdZn7 complex [Pd(ZnCp*)4(ZnMe)2{Zn(tmeda)}].

The synthesis, structural characterization, and bonding situation analysis of a novel, all-zinc, hepta-coordinated palladium complex [Pd(ZnCp*)(4)(ZnMe)(2){Zn(tmeda)}] (1) is reported. The reaction of the substitution labile d(10) metal starting complex [Pd(CH(3))(2)(tmeda)] (tmeda = N,N,N',N'-tetramethyl-ethane-1,2-diamine) with stoichiometric amounts of [Zn(2)Cp*(2)] (Cp* = pentamethylcyclopentadienyl) results in the formation of [Pd(ZnCp*)(4)(ZnMe)(2){Zn(tmeda)}] (1) in 35% yield. Compound 1 has been fully characterized by single-crystal X-ray diffraction, (1)H and (13)C NMR spectroscopy, IR spectroscopy, and liquid injection field desorption ionization mass spectrometry. It consists of an unusual [PdZn(7)] metal core and exhibits a terminal {Zn(tmeda)} unit. The bonding situation of 1 with respect to the properties of the three different types of Zn ligands Zn(R,L) (R = CH(3), Cp*; L = tmeda) bonded to the Pd center was studied by density functional theory quantum chemical calculations. The results of energy decomposition and atoms in molecules analysis clearly point out significant differences according to R vs L. While Zn(CH(3)) and ZnCp* can be viewed as 1e donor Zn(I) ligands, {Zn(tmeda)} is best described as a strong 2e Zn(0) donor ligand. Thus, the 18 valence electron complex 1 nicely fits to the family of metal-rich molecules of the general formula [M(ZnR)(a)(GaR)(b)] (a + 2b = n ≥ 8; M = Mo, Ru, Rh; Ni, Pd, Pt; R = Me, Et, Cp*).

Molecular alloys: experimental and theoretical investigations on the substitution of zinc by cadmium and mercury in the homologous series [Mo(M'R)12] and [M(M'R)8] (M=Pd, Pt; M'=Zn, Cd, Hg).

The synthesis and structural characterization of novel, metal-rich, highly coordinated compounds [Mo(M'R)(12)] and [M(M'R)(8)] (M: Pd, Pt, Mo; M': Zn, Cd; R: Me=CH(3), Cp*=pentamethylcyclopentadienyl) are reported. Additionally, a description of the bonding situation of the new compounds by means of quantum-chemical calculations is presented including the Hg analogues. Reaction of [Pt(GaCp*)(4)] with CdMe(2) results in the formation of the unprecedented all-Cd coordinated [Pt(CdMe)(4)(CdCp*)(4)] (1). Similarly, the treatment of the all-Zn coordinated [Pd(ZnMe)(4)(ZnCp*)(4)] with CdMe(2) affords the novel Zn/Cd mixed compound [Pd(CdMe)(4)(ZnCp*)(4)] (2). The related Zn/Cd mixed compound [Mo(ZnCp*)(3)(CdMe)(9)] (3) is prepared by reaction of [Mo(ZnCp*)(4)(GaMe)(4)] with an excess amount of CdMe(2). All compounds were analyzed by (1)H and (13)C NMR spectroscopy, elemental analysis, and single-crystal X-ray diffraction. The bonding situation of these highly coordinated, metal-rich molecules 1-3 were studied by quantum-chemical calculations using density functional theory (DFT) at the BP86/TZ2P+ level, atoms-in-molecules (AIM) analysis, and energy-decomposition analysis (EDA), as well as the its natural orbitals for chemical valence variation (EDA-NOCV) and including the hypothetically all-Hg-coordinated analogues. The results point out that the radial interactions M-M' in the icosahedral compounds that have twelve ligands are best described as classical electron-pair-sharing covalent bonds, whereas the dodecahedral species, which have eight ligands, exhibit metal-ligand donor-acceptor bonds. The attractive interactions between the metal-ligand fragments M'R by means of M'-M' bonds are weaker but not insignificant. All complexes fulfill the 18-electron rule. The analysis clarifies the electronic structures as being distinctly different from typical endohedral clusters M@(M''R)(n) that exhibit strong peripheral M''-M'' interactions: The M'-M' bonds are not strong enough to yield stable (M'R)(n) cages.

First dinuclear copper/gallium complexes: supporting Cu0 and Cu(I) centres by low-valent organogallium ligands.

The synthesis and structural characterisation of low-valent dinuclear copper(I) and copper(0) complexes supported by organogallium ligands has been accomplished for the first time by the reductive coordination reaction of [GaCp*] (Cp*=pentamethylcyclopentadienyl) and [Ga(ddp)] (ddp=HC(CMeNC(6)H(3)-2,6-iPr(2))(2) 2-diisopropylphenylamino-4-diisopropylphenylimino-2-pentene) with readily available copper(II) and copper(I) precursors. The treatment of CuBr(2) and Cu(OTf)(2) (OTf=CF(3)SO(3)) with [Ga(ddp)] under mild conditions resulted in elimination of [Ga(L)(2)(ddp)] (L=Br, OTf) and afforded the novel gallium(I)/copper(I) compounds [{(ddp)GaCu(L)}(2)] (L=Br (1), OTf (2)). The single-crystal X-ray structure determinations of 1 and 2 reveal that these molecules are composed of {(ddp)GaCu(L)} dimeric units, with planar Cu(I)-Ga(I) four-membered rings and short Cu(I)...Cu(I) distances, with 2 exhibiting the shortest Cu(I)Cu(I) contact reported to date of 2.277(3) A. The all-gallium coordinated dinuclear [Cu(2)(GaCp*)(mu-GaCp*)(3)Ga(OTf)(3)] (3) is formed when Cu(OTf)(2) is combined with [GaCp*] instead of [Ga(ddp)]. Notably, in the course of this redox reaction Lewis acidic Ga(OTf)(3) is formed, which coordinates to one of the electron-rich copper(0) centres. Compound 3 is suggested as the first case of a structurally characterised complex of copper(0). By changing the copper(II) to a copper(I) source, that is, [Cu(cod)(2)][OTf] (cod=1,5-cyclooctadiene), the salt [Cu(2)(GaCp*)(3)(mu-GaCp*)(2)][OTf](2) (4) is formed, the cationic part of which is related to previously described isoelectronic dinuclear d(10) complexes of the type [M(2)(GaCp*)(5)] (M=Pd, Pt).

Molecular alloys, linking organometallics with intermetallic Hume-Rothery phases: the highly coordinated transition metal compounds [M(ZnR)(n)] (n >or= 8) containing organo-zinc ligands.

This paper presents the preparation, characterization and bonding analyses of the closed shell 18 electron compounds [M(ZnR)(n)] (M = Mo, Ru, Rh, Ni, Pd, Pt, n = 8-12), which feature covalent bonds between n one-electron organo-zinc ligands ZnR (R = Me, Et, eta(5)-C(5)(CH(3))(5) = Cp*) and the central metal M. The compounds were obtained in high isolated yields (>80%) by treatment of appropriate GaCp* containing transition metal precursors 13-18, namely [Mo(GaCp*)(6)], [Ru(2)(Ga)(GaCp*)(7)(H)(3)] or [Ru(GaCp*)(6)(Cl)(2)], [(Cp*Ga)(4)RhGa(eta(1)-Cp*)Me] and [M(GaCp*)(4)] (M = Ni, Pd, Pt) with ZnMe(2) or ZnEt(2) in toluene solution at elevated temperatures of 80-110 degrees C within a few hours of reaction time. Analytical characterization was done by elemental analyses (C, H, Zn, Ga), (1)H and (13)C NMR spectroscopy. The molecular structures were determined by single crystal X-ray diffraction. The coordination environment of the central metal M and the M-Zn and Zn-Zn distances mimic the situation in known solid state M/Zn Hume-Rothery phases. DFT calculations at the RI-BP86/def2-TZVPP and BP86/TZ2P+ levels of theory, AIM and EDA analyses were done with [M(ZnH)(n)] (M = Mo, Ru, Rh, Pd; n = 12, 10, 9, 8) as models of the homologous series. The results reveal that the molecules can be compared to 18 electron gold clusters of the type M@Au(n), that is, W@Au(12), but are neither genuine coordination compounds nor interstitial cage clusters. The molecules are held together by strong radial M-Zn bonds. The tangential Zn-Zn interactions are generally very weak and the (ZnH)(n) cages are not stable without the central metal M.

Syntheses and crystal structures of ruthenium and rhodium olefin complexes containing GaCp.

The reactivity of olefin containing complexes of the d(8) metals Ru(0) and Rh(I) toward GaCp* and AlCp* is presented. [Ru(eta(4)-butadiene)(PPh(3))(3)] reacts with GaCp* to give the substitution product [Ru(eta(4)-butadiene)(PPh(3))(2)(GaCp*)] (1), which proved to be stable in the presence of GaCp* even under hydrogenolytic conditions. In contrast, the bis-styrene complex [Ru(PPh(3))(2)(styrene)(2)] undergoes full substitution of the olefin ligands to give [Ru(PPh(3))(2)(GaCp*)(3)] (2), whereas reaction of [Ru(eta(2),eta(2)-COD)(eta(6)-COT)] (COD = 1,5-cyclooctadiene, C(8)H(12), COT = 1,3,5-cyclooctatriene, C(8)H(10)) and GaCp* leads to [Ru(eta(2),eta(2)-COD)(GaCp*)(3)] (3) under mild hydrogenolytic conditions. Analogously, the Rh(I) compounds [{Rh(eta(2),eta(2)-NBD)(PCy(3))(2)}{BAr(F)}] (NBD = norbornadiene) and [{Rh(eta(2),eta(2)-COD)(2)}{BAr(F)}] ({BAr(F)}= B{[C(6)H(3)(CF(3))(2)](4)) yield the complexes [{Rh(eta(2),eta(2)-NBD)(PCy(3))(GaCp*)(2)}{BAr(F)}] (4), [{Rh(eta(2),eta(2)-COD)(GaCp*)(3)}{BAr(F)}] (5), and [{Rh(eta(2),eta(2)-COD)(AlCp*)(3)}{BAr(F)]}] (6) upon reaction with the appropriate ECp* ligand (E = Al, Ga). All new complexes have been characterized by means of (1)H and (13)C NMR spectroscopy and elemental analysis, as well as X-ray single crystal structure analysis in the case of 1-5.

Organometallic chemistry of Ga(+): formation of an unusual gallium dimer in the coordination sphere of ruthenium.

New insights into the distinct organometallic chemistry of the Ga(+) ion are presented. Ga(+) reacts as a strong electrophile with the electron rich ligand trismethylene-methane (C(CH(2))(3) (2-)) attached at Ru by insertion into a Ru--C bond. The resulting "gallamethylallyl" ligand behaves like strong nucleophile similar to known monovalent GaR species. This donor property leads to the dimeric structure of the product [{Ru(GaCp*)(3)[eta(3)-(CH(2))(2)C{CH(2)(mu-Ga)}]}(2)][(BAr(F))(2)] (4) (Cp*=C(5)Me(5), [BAr(F)]=[B{C(6)H(3)(CF(3))(2)}(4)]). Very unexpectedly, the two gallium ligands in this dimer are found in close vicinity to each other with a distance in the range of Ga--Ga bonds. Indeed, AIM calculations confirm a weak attractive closed shell Ga--Ga interaction. Finally, a novel example of a complex with substituent-free Ga(+) as a ligand was found in the compound [Ru(PCy(3))(2)(GaCp*)(2)(Ga)][BAr(F)] (6) (Cy=C(6)H(11), cyclohexyl), the very short Ru--Ga bond length confirming the assumption that Ga(+) represents a pure sigma/pi-accepting ligand in this case.

Mixed phosphine and group-13 metal ligator complexes [(PR3)(a)M(ECp*)b] (M = Mo, Ni; E = Ga, Al; R = C6H5, cyclo-C6H11, CH3).

Treatment of [Mo(N(2))(PMe(3))(5)] with two equivalents GaCp* (Cp* = η(5)-C(5)(CH(3))(5)) leads to the formation of cis-[Mo(GaCp*)(2)(PMe(3))(4)] (1), while AlCp* did not react with this precursor. In addition, [Ni(GaCp*)(2)(PPh(3))(2)] (2a), [Ni(AlCp*)(2)(PPh(3))(2)] (2b), [Ni(GaCp*)(2)(PCy(3))(2)] (3a), [Ni(GaCp*)(2)(PMe(3))(2)] (3b), [Ni(GaCp*)(3)(PCy(3))] (4) and [Ni(GaCp*)(PMe(3))(3)] (5) have been prepared in high yields by a direct synthesis from [Ni(COD)(2)] and stoichiometric amounts of the ligands PR(3) and ECp* (E = Al, Ga), respectively. All compounds have been fully characterized by (1)H, (13)C, and (31)P NMR spectroscopy, elemental analysis and single crystal X-ray diffraction studies.

Zinc-rich compounds of iron and cobalt: formation of [Fe2Zn(n)] (n = 2-4) and [Co2Zn3] cores.

The reactions of heteroleptic GaCp*/CO containing transition metal complexes of iron and cobalt, namely [(CO)(3)M(µ(2)-GaCp*)(m)M(CO)(3)] (Cp* = pentamethylcyclopentadienyl; M = Fe, m = 3; M = Co, m = 2) and [Fe(CO)(4)(GaCp*)], with ZnMe(2) in toluene and the presence of a coordinating co-solvent were investigated. The reaction of the iron complex [Fe(CO)(4)(GaCp*)] with ZnMe(2) in presence of tetrahydrofurane (thf) leads to the dimeric compound [(CO)(4)Fe{µ(2)-Zn(thf)(2)}(2)Fe(CO)(4)] (1). Reaction of [(CO)(3)Fe(µ(2)-GaCp*(3))Fe(CO)(3)] with ZnMe(2) and stoichiometric amounts of thf leads to the formation of [(CO)(3)Fe{µ(2)-Zn(thf)(2)}(2)(µ(2)-ZnMe)(2)Fe(CO)(3)] (2) containing {Zn(thf)(2)} as well as ZnMe ligands. Using pyridine (py) instead of thf leads to [(CO)(3)Fe{µ(2)-Zn(py)(2)}(3)Fe(CO)(3)] (3) via replacement of all GaCp* ligands by three{Zn(py)(2)} groups. In contrast, reaction of [(CO)(3)Co(µ(2)-GaCp*)(2)Co(CO)(3)] with ZnMe(2) in the presence of py or thf leads in both cases to the formation of [(CO)(3)Co{µ(2)-ZnL(2)}(µ(2)-ZnCp*)(2)Co(CO)(3)] (L = py (4), thf (5)) via replacement of GaCp* with {Zn(L)(2)} units as well as Cp* transfer from the gallium to the zinc centre. All compounds were characterised by NMR spectroscopy, IR spectroscopy, single crystal X-ray diffraction and elemental analysis.

One electron organozinc ligands in metal rich molecules by Ga/Zn exchange: from Cp*Rh(GaCp*)2 to Cp*Rh(ZnR)4 units.

Two unusual compounds, [{Cp*Rh(ZnCp*)(2)(ZnMe)(ZnCl)}(2)] (1) and [Cp*(2)Rh][(Cp*Rh)(6)Zn(18)Cl(12)(mu(6)-Cl)] (2), both bearing closed shell 18-electron square pyramidal Cp*RhZn(4) building units were obtained by combined Ga/Zn, Me/Cp* and Me/Cl exchange upon treatment of [Cp*Rh(GaCp*)(2)(GaCl(2)Cp*)] with ZnMe(2) (Cp* = pentamethylcyclopentadienyl).

Synthesis and structure of electron rich ruthenium polyhydride complexes and clusters containing AlCp* and GaCp*.

The reactions of the ruthenium hydride complexes [{Ru(COD)(H)(NH2NMe2)3}{BArF}] (BArF=B{C6H3(CF3)2}4), [{Cp*Ru}2(micro-H)4] and [{Cp*Ru}3(micro-H)3(micro3-H)2] with GaCp* and AlCp* are investigated. The reaction of [{Ru(COD)(H)(NH2NMe2)3}{BArF}] with GaCp* leads to substitution of the hydrazine ligands by GaCp* and the formation of [{Ru(COD)(H)(GaCp*)3}{BArF}] (), while the reactions of [{Cp*Ru}2(micro-H)4] and [{Cp*Ru}3(micro-H)3(micro3-H)2] with ECp* (E=Al, Ga) results in the formation of the polyhydride clusters [{Cp*Ru(micro-H)(H)(micro-ECp*)}2] (, E=Ga; , E=Al) and [{Cp*Ru}3(micro-H)5(micro3-ECp*)] (, E=Al; , E=Ga). All Ru complexes react upon coordination of the group 13 ligand without loss of H2 or reductive elimination of Cp*H and without insertion into the Ru-H bonds; some of the products, however, showing Ru-H-E bridging motifs. All compounds were characterized by NMR spectroscopy, elemental analysis and single crystal X-ray diffraction studies.

Reactions of cationic transition metal acetonitrile complexes [M(CH3CN)n]m+ with GaCp*: novel gallium complexes of iron, cobalt, copper and silver.

The reactions of the cationic transition metal acetonitrile complexes [M(CH3CN)n]m+ (m = 2: M = Fe, Co and m = 1: M = Cu, Ag) with GaCp* were investigated. The reaction of [Fe(CH3CN)6][BArF]2 (BAr(F) = [B{C6H3(CF3)2}4) with GaCp* leads to [Cp*Fe(GaCp*)3][BAr(F)] (1) via a redox neutral Cp* transfer and [Ga2Cp*][BAr(F)] as a by-product while the formation of [Cp*Co(GaCp*)3][BAr(F)]2 (2) from [Co(CH3CN)6][BAr(F)]2 is accompanied by oxidation of Co(II) to Co(III) with GaCp* as the oxidant. The reactions of [Cu(CH3CN)4][BAr(F)] and Ag[BPh4] with GaCp* lead to the formation of the homoleptic compounds [Cu(GaCp*)4][BAr(F)] (4) and [Ag(GaCp*)4][BPh4] (5), while treatment of Ag[CF3SO3] with GaCp* leads to the dimeric complex [Ag2(GaCp*)3(micro-GaCp*)2][CF3SO3]2 (6). All compounds were characterized by NMR spectroscopy, single crystal X-ray diffraction and elemental analysis.