Ge(9)=Ge(9)=Ge(9)](6-): a linear trimer of 27 germanium atoms

The title anion was synthesized by oxidation of nido-Ge94- with Ph3P or Ph3As in ethylenediamine solution. It was structurally characterized in the compound (Rb-2,2,2-crypt)6[Ge9=Ge9=Ge9].3en (2,2,2-crypt = 4,7,13,16,21,24-hexaoxa-1,10-diazabicyclo[8.8.8]hexacosane) crystallized from the solution. The anion is a linear trimer of nine-atom clusters with the shape of tricapped trigonal prisms elongated along two of the three prismatic edges. Each pair of clusters is connected by two exo-bonds.     

Surprising acid/base and ion-sequestration chemistry of Sn9(4-): HSn9(3-), Ni@HSn9(3-), and the Sn9(3-) ion revisited

K(4)Sn(9) dissolves in ethylenediamine (en) to give equilibrium mixtures of the diamagnetic HSn(9)(3-) ion along with K(x)Sn(9)((4-x)-) ion pairs, where x = 0, 1, 2, 3. The HSn(9)(3-) cluster is formed from the deprotonation of the en solvent and is the conjugate acid of Sn(9)(4-). DFT studies show that the structure is quite similar to the known isoelectronic RSn(9)(3-) ions (e.g., R = i-Pr). The hydrogen atom of HSn(9)(3-) (δ = 6.18 ppm) rapidly migrates among all nine Sn atoms in an intramolecular fashion; the Sn(9) core is also highly dynamic on the NMR time scale. The HSn(9)(3-) cluster reacts with Ni(cod)(2) to give the Ni@HSn(9)(3-) ion containing a hydridic hydrogen (δ = -28.3 ppm) that also scrambles across the Sn(9) cluster. The Sn(9)(4-) ion competes effectively with 2,2,2-crypt for binding K(+) in en solutions, and the pK(a) of HSn(9)(3-) is similar to that of en (i.e., Sn(9)(4-) is a very strong Br?nsted base with a pK(b) comparable to that of the NH(2)CH(2)CH(2)NH(-) anion). Competition studies show that the HSn(9)(3-) ? Sn(9)(4-) + H(+) equilibrium is fully reversible. The HSn(9)(3-) anion is present in significant concentrations in en solutions containing 2,2,2-crypt, yet it has gone undetected for over 30 years.     

The Pb12(2-) and Pb10(2-) zintl ions and the M@Pb12(2-) and M@Pb10(2-) cluster series where M = Ni, Pd, Pt

Ethylenediamine (en) solutions of K4Pb9 react with toluene solutions of ML4 (M = Pt, Pd, L = PPh3; M = Ni, L2= COD) and 2,2,2-crypt to give M@Pb12(2-) cluster anions (M = Pt (1), Pd (2), Ni (3)) as the [K(2,2,2-crypt)]+ salts in low (Ni) to good (Pt) yields. The ions have near perfect Ih point symmetry and have been characterized by X-ray diffraction, 207Pb NMR and LDI-TOF mass spectrometry studies. For M = Ni, the primary product formed is the D4d Ni@Pb10(2-) cluster that has also been structurally characterized. The M@Pb10(2-) clusters (M = Pd, Pt) and the new Zintl ions closo-Pb10(2-) and closo-Pb12(2-) were formed in the gas phase but have not been detected in solution or the solid state. The structural trends of these series of clusters have been investigated through DFT calculations. The Ni@Pb10(2-) cluster is dynamic on the 207Pb NMR time scale at -45 degrees C and 104.7 MHz. The M@Pb12(2-) ions show unusually deshielded 207Pb NMR chemical shifts that presumably arise from sigma-aromatic effects associated with their high symmetries. In the solid state, the salts form superlattices of cations and anions (e.g. the AlB2 lattice of [K(2,2,2-crypt)](2)[Pt@Pb12]) and are prototypes for "assembled cluster materials".     

On the stability of an unsupported mercury-mercury bond linking group 15 Zintl clusters

The dimeric Zintl ion [Hg(2)(As(7))(2)](4-) has been synthesized with high crystalline yield from the reaction of an ethylendiamine solution of the intermetallic Zintl phase K(3)As(7) with diphenyl mercury. Single crystal X-ray diffraction of [K(2,2,2-crypt)](4)[Hg(2)As(14)], 1 (2,2,2-crypt = 4,7,13,16,21,24-hexaoxa-1,10-diazabicyclo[8.8.8]-hexacosane), reveals that the cluster anion exhibits a Hg-Hg bond and the compound has been further characterized using Raman spectroscopy, cyclic voltammetry and its band gap energy was measured. Theoretical studies provide a microscopic understanding of the bonding in this unusual compound.     

Rational synthesis of [Ge9{Si(SiMe3)3}3]- from its parent Zintl ion Ge9(4-)

Reported is the first rational synthesis of a trisubstituted deltahedral Zintl ion, [Ge(9){Si(SiMe(3))(3)}(3)](-) in this case, by the addition of the three substituents in a reaction of the parent naked deltahedral Zintl ion Ge(9)(4-) with {(Me(3)Si)(3)Si}Cl. The new species were crystallized and structurally characterized in [K(2,2,2-crypt)](2)[Ge(9){Si(SiMe(3))(3)}(3)] (monoclinic, P2(1)/c, a = 26.497(3) ?, b = 24.090(2) ?, c = 29.268(3) ?, β = 113.888(2)°, V = 17082(3) ?(3), Z = 8, R1/wR2 = 0.0436/0.0812 for the observed data and 0.1023/0.1010 for all data).     

The Zintl ion [As7]2-: an example of an electron-deficient As(x) radical anion

[K(2,2,2-crypt)](2)[As(7)]·THF, 1 (2,2,2-crypt = 4,7,13,16,21,24-hexaoxa-1,10-diazabicyclo[8.8.8]hexacosane) is the first well characterized seven-atom radical anion of group 15. UV-Vis spectroscopy confirms the presence and electronic structure of [As(7)](2-). Cyclic voltammetry in DMF solution shows the As(7)(3-)/As(7)(2-) redox couple as a one-electron reversible process. Theoretical investigations explore the bonding and properties of compound 1.     

The [Sn(9)Pt(2)(PPh(3))](2)(-) and [Sn(9)Ni(2)(CO)](3)(-) complexes: two markedly different Sn(9)M(2)L transition metal zintl ion clusters and their dynamic behavior

[Sn(9)Pt(2)(PPh(3))](2)(-) (2) was prepared from Pt(PPh(3))(4), K(4)Sn(9), and 2,2,2-cryptand in en/toluene solvent mixtures. The [K(2,2,2-cryptand)](+) salt is very air and moisture sensitive and has been characterized by ESI-MS, variable-temperature (119)Sn, (31)P, and (195)Pt NMR and single-crystal X-ray diffraction studies. The structure of 2 comprises an elongated tricapped Sn(9) trigonal prism with a capping PtPPh(3), an interstitial Pt atom, a hypercloso electron count (10 vertex, 20 electron) and C(3)(v)() point symmetry. Hydrogenation trapping experiments and deuterium labeling studies showed that the formation of 2 involves a double C-H activation of solvent molecules (en or DMSO) with the elimination of H(2) gas. The ESI-MS analysis of 2 showed the K[Sn(9)Pt(2)(PPh(3))](1)(-) parent ion, an oxidized [Sn(9)Pt(2)(PPh(3))](1)(-) ion, and the protonated binary cluster anion [HSn(9)Pt(2)](1)(-). 2 is highly fluxional in solution giving rise to a single time-averaged (119)Sn NMR signal for all nine Sn atoms but the Pt atoms remain distinct. The exchange is intramolecular and is consistent with a rigid, linear Pt-Pt-PPh(3) rod embedded in a liquidlike Sn(9) matrix. [Sn(9)Ni(2)(CO)](3)(-) (3) was prepared from Ni(CO)(2)(PPh(3))(2), K(4)Sn(9), and 2,2,2-cryptand in en/toluene solvent mixtures. The [K(2,2,2-cryptand)](+) salt is very air and moisture sensitive, is paramagnetic, and has been characterized by ESI-MS, EPR, and single-crystal X-ray diffraction. Complex 3 is a 10-vertex 21-electron polyhedron, a slightly distorted closo-Sn(9)Ni cluster with an additional interstitial Ni atom and overall C(4)(v)() point symmetry. The EPR spectrum showed a five-line pattern due to 4.8-G hyperfine interactions involving all nine tin atoms. The ESI-MS analysis showed weak signals for the potassium complex [K(2)Sn(9)Ni(2)(CO)](1-) and the ligand-free binary ions [K(2)Sn(9)Ni(2)](1)(-), [KSn(9)Ni(2)](1)(-), and [HSn(9)Ni(2)](1)(-).     

Heteroatomic molecular clusters derived from Group 15 Zintl ion cages: synthesis and isolation of [M2(HP7)2](2-) (M=Ag, Au), two novel cluster anions exhibiting metallophilic interactions

Ethylenediamine (en) solutions of K(3)P(7) and 2,2,2-crypt (4,7,13,16,21,24-hexaoxa-1,10-diazabicyclo[8.8.8]hexacosane) were reacted with the homoleptic group 11 complexes [M(nbe)(3)][SbF(6)] (M = Ag, Au; nbe = norbornene) yielding two novel cluster anions, [M(2)(HP(7))(2)](2-), both of which were isolated in low crystalline yields as [K(2,2,2-crypt)](2)[M(2)(HP(7))(2)] (M = Ag (1) and Au (2)). Optimization of the reaction conditions by incorporation of a proton source (ammonium tetraphenylborate) and the replacement of the light-sensitive nbe adducts of silver and gold with the chloride salts MCl (M = Ag, Au) was found to greatly increase the yield and purity in which 1 and 2 were isolated. Compounds 1 and 2 were characterized by single crystal X-ray diffraction, electrospray ionization mass-spectrometry (ESI- MS), elemental analysis, and (1)H and (31)P NMR spectroscopy. Density functional theory (DFT) calculations on the cluster anions were also conducted.     

A highly distorted open-shell endohedral Zintl cluster: [Mn@Pb12]3-

Reaction of an ethylenediamine (en) solution of K(4)Pb(9) and 2,2,2-crypt (4,7,13,16,21,24-hexaoxa-1,10-diazabicyclo[8.8.8]hexacosane) with a tetrahydrofuran (THF) solution of Mn(3)(Mes)(6) (Mes = 2,4,6-trimethylphenyl) yielded the anionic cluster [Mn@Pb(12)](3-). This species was observed in the positive and negative ion-mode electrospray mass-spectra of the crude reaction mixture. The crystalline samples obtained from such solutions allowed us to confirm the composition of the sample as [K(2,2,2-crypt)](3)[Mn@Pb(12)]·1.5en (1). Because of numerous issues related to crystal sample quality and crystallographic disorder a high-quality crystal structure solution could not be obtained. Despite this, however, the data collected permit us to draw reasonable conclusions about the charge and connectivity of the [Mn@Pb(12)](3-) cluster anion. Crystals of 1 were further characterized by elemental analysis and electron paramagnetic resonance (EPR). Density Functional Theory (DFT) calculations on such a system reveal a highly distorted endohedral cluster anion, consistent with the structural distortions observed by single crystal X-ray diffraction. The cluster anions are considerably expanded compared to the 36-electron closed-shell analogue [Ni@Pb(12)](2-) and, moreover, exhibit significant low-symmetry distortions from the idealized icosahedral (I(h)) geometry that is characteristic of related endohedral clusters. Our computations indicate that there is substantial transfer of electron density from the formally Mn(-I) center to the low-lying vacant orbitals of the [Pb(12)](2-) cage.     

Ligand-free deltahedral clusters of silicon in solution: synthesis, structure, and electrochemistry of Si9(2-)

Deltahedral nine-atom clusters of silicon, Si(9)(2-), were synthesized by mild oxidation of a liquid ammonia solution of K(12)Si(17) with Ph(3)GeCl in the presence of 18-crown-6 (1,4,7,10,13,16-hexaoxacyclooctadecane) or 2,2,2-crypt (4,7,13,16,21,24-hexaoxa-1,10-diazabicyclo[8.8.8]hexacosane). The clusters were structurally characterized in [K(18-crown-6)](2)Si(9).C(5)H(5)N (yellow; orthorhombic, Pnma; a = 14.013(1), b = 18.108 (1), c = 18.320 (1) A; Z = 4) crystallized from a pyridine solution of the product of the aforementioned reaction in liquid ammonia. Si(9)(2-) is the first unequivocally characterized nine-atom cluster of group 14 with a charge of 2-. In addition to pyridine, the product from the reaction in liquid ammonia is also soluble in DMF, and the Si(9)(2-) clusters were characterized by mass spectrometry in such a solution. The more reduced clusters Si(9)(3-) have also been crystallized from pyridine solution. Cyclic voltammetry in both pyridine and DMF solutions clearly shows the Si(9)(2-)/Si(9)(3-) redox couple as one-electron reversible process. The structural similarities and differences between Si(9)(3-) and Si(9)(2-) are discussed herein.     

Alkylation of Deltahedral Zintl clusters: synthesis of [R-Ge9-Ge9-R]4- (R = tBu, sBu, nBu, tAm and structure of [tBu-Ge9-Ge9-tBu]4-

Reactions of nine-atom deltahedral clusters (Zintl ions) of germanium, Ge9n- (n = 2, 3, 4), with alkyl chlorides, RCl (R = tBu, nBu, sBu, tAm), yielded the corresponding dialkylated dimers of Ge9 clusters [R-Ge9-Ge9-R]4-. The tBu derivative with [K(2,2,2-crypt)]+ countercations was characterized in the solid state by single-crystal X-ray diffraction as [K(2,2,2-crypt)]4[tBu-Ge9-Ge9-tBu].7en (monoclinic, C2/c, a = 35.0914(10) A, b = 24.8161(6) A, and c = 16.8782(5) A, beta = 94.0136(17) degrees , V = 14662.0(7) A3, and Z = 4) and in solution by 1H and 13C NMR. All species were also characterized in solution by electrospray mass spectrometry in the negative-ion mode. These are the first main group deltahedral clusters functionalized with purely organic substituents.     

Synthesis, Structure, and Reactivities of [eta(2)-P(7)M(CO)(4)](3)(-), [eta(2)-HP(7)M(CO)(4)](2)(-), and [eta(2)-RP(7)M(CO)(4)](2)(-) Zintl Ion Complexes Where M = Mo, W

Ethylenediamine (en) solutions of [eta(4)-P(7)M(CO)(3)](3)(-) ions [M = W (1a), Mo (1b)] react under one atmosphere of CO to form microcrystalline yellow powders of [eta(2)-P(7)M(CO)(4)](3)(-) complexes [M = W (4a), Mo (4b)]. Compounds 4 are unstable, losing CO to re-form 1, but are highly nucleophilic and basic. They are protonated with methanol in en solvent giving [eta(2)-HP(7)M(CO)(4)](2)(-) ions (5) and are alkylated with R(4)N(+) salts in en solutions to give [eta(2)-RP(7)M(CO)(4)](2)(-) complexes (6) in good yields (R = alkyl). Compounds 5 and 6 can also be prepared by carbonylations of the [eta(4)-HP(7)M(CO)(3)](2)(-) (3) and [eta(4)-RP(7)M(CO)(3)](2)(-) (2) precursors, respectively. The carbonylations of 1-3 to form 4-6 require a change from eta(4)- to eta(2)-coordination of the P(7) cages in order to maintain 18-electron configurations at the metal centers. Comparative protonation/deprotonation studies show 4 to be more basic than 1. The compounds were characterized by IR and (1)H, (13)C, and (31)P NMR spectroscopic studies and microanalysis where appropriate. The [K(2,2,2-crypt)](+) salts of 5 were characterized by single crystal X-ray diffraction. For 5, the M-P bonds are very long (2.71(1) ?, average). The P(7)(3)(-) cages of 5 are not displaced by dppe. The P(7) cages in 4-6 have nortricyclane-like structures in contrast to the norbornadiene-type geometries observed for 1-3. (31)P NMR spectroscopic studies for 5-6 show C(1) symmetry in solution (seven inequivalent phosphorus nuclei), consistent with the structural studies for 5, and C(s)() symmetry for 4 (five phosphorus nuclei in a 2:2:1:1:1 ratio). Crystallographic data for [K(2,2,2-crypt)](2)[eta(2)-HP(7)W(CO)(4)].en: monoclinic, space group C2/c, a = 23.067(20) ?, b = 12.6931(13) ?, c = 21.433(2) ?, beta = 90.758(7) degrees, V = 6274.9(10) ?(3), Z = 4, R(F) = 0.0573, R(w)(F(2)) = 0.1409. For [K(2,2,2-crypt)](2)[eta(2)-HP(7)Mo(CO)(4)].en: monoclinic, space group C2/c, a = 22.848(2) ?, b = 12.528(2) ?, c = 21.460(2) ?, beta = 91.412(12) degrees, V = 6140.9(12) ?(3), Z = 4, R(F) = 0.0681, R(w)(F(2)) = 0.1399.     

Tri-metallic deltahedral Zintl ions: experimental and theoretical studies of the novel dimer [(Sn6Ge2Bi)2]4-

We report the synthesis, characterization, and computational rationalization of the first trimetallic deltahedral Zintl ions. The novel nine-atom clusters were structurally characterized as dimers of [(Sn(6)Ge(2)Bi)(2)](4-) with Ge-Ge intercluster bonds. They are synthesized either by reacting bimetallic clusters (Sn(9-x)Ge(x))(4-) with BiPh(3) or by direct extraction from precursors with nominal composition "K(4)Ge(4)Sn(4)Bi".     

Solution dynamics and gas-phase chemistry of Pd2@Sn18 4-

Sn9(4-) reacts with Pd(PPh3)4 in ethylenediamine/toluene solvent mixtures in the presence of 2,2,2-cryptand to give the Pd2@Sn18(4-) cluster as the K(2,2,2,-crypt)+ salt. The cluster is isostructural with Pd2@Ge18(4-) and has a nuclearity different from that of the Pt and Ni analogues, Ni2@Sn17(4-) and Pt2@Sn17(4-). The Pd2@Sn18(4-) ion has a deltahedral capsulelike structure with 40 cluster bonding electrons and is the largest free-standing polystannide characterized to date. Like Pt2@Sn17(4-), the Pd2@Sn18(4-) complex is highly dynamic in solution, showing a single (119)Sn NMR resonance indicative of an intramolecular liquidlike dynamic exchange. LDI-MS studies of the crystalline sample show extensive fragmentation and the formation of five gas-phase cluster series: Sn(x)- (1 < x < 12), PdSn(x-1) - (4 < x < 18), Pd 2Sn(x-2) - (6 < x < 21), Pd3Sn(x-3) - (8 < x < 21), and Pd 4Sn(x-4) - (13 < x < 21). The most abundant ion in the gas phase is the PdSn(10) - cluster, which presumably has an Sn(10) bicapped-square-antiprismatic structure with an endohedral Pd (e.g., Ni@Pb(10)(2-)).     

Tin-based organo-Zintl ions: alkylation and alkenylation of Sn9(4-)

Reactions of nine-atom deltahedral clusters (Zintl ions) of tin, Sn 9 (4-), with alkyl chlorides, RCl (R = (t) Bu, (n) Bu, (s) Bu), and alkynes (Me3Si-C[triple bond]C-SiMe3, Ph-C[triple bond]CH) yielded the corresponding alkylated and alkenylated clusters [Sn 9-R] (3-). The triple bonds of the alkynes are hydrogenated to double bonds in the process. These are the first tin-based organo-Zintl ions, that is Zintl ions of tin that were subsequently functionalized with organic groups. They are analogous to the recently reported germanium-based derivatives. The (t) Bu-, vinyl-, and styrene-functionalized clusters [Sn 9- (t) Bu] (3-), [Sn 9-CH=CH 2] (3-), and [Sn 9-CH=CH-Ph] (3-), respectively, were structurally characterized in the solid state with [K(2,2,2-crypt)] (+) countercations and in solution by electrospray mass spectrometry. Crystal data: [K(2,2,2-crypt)] 3[Sn 9- (t) Bu].2py, triclinic, P1, a = 14.4259(3), b = 16.2725(4), and c = 22.5593(5) A, alpha = 86.092(1), beta = 78.952(1), and gamma = 65.114(1) degrees , V = 4714.48(7) A (3), Z = 2; [K(2,2,2-crypt)] 3[Sn 9-CH=CH 2].2py, triclinic, P-1, a = 15.6988(3), b = 17.4195(4), and c = 17.4432(4) A, alpha = 86.299(1), beta = 81.566(1), and gamma = 85.349(1) degrees , V = 4696.27(18) A (3), Z = 2; [K(2,2,2-crypt)] 3[Sn 9-CH=CH-Ph].tol.0.75py, monoclinic, C2/c, a = 38.5883(9), b = 23.3893(5), and c = 25.0192(5) A, beta = 120.269(1) degrees , V = 19502.6(7) A (3), Z = 8.     

Synthesis and Crystal Structure of [K（2,2,2-crypt）]_3Sb_（11）

The title complex [K(2,2,2-crypt)]3Sb11 has been prepared by the reaction of K3Cd2Sb with Cu-C≡CH in ethylenediamine in the presence of 2,2,2-crypt, and characterized by low temperature X-ray structure analysis. The crystal is of orthorhombic system, space group C2221 with a = 15.475(3), b = 22.807(5), c = 24.834(6), V = 8765(3)3, Dc = 1.960 g/cm3, C54H108K3N6O18Sb11, Mr = 2586.01, F(000) = 4944, μ = 3.531 mm-1, Z = 4, R = 0.0442 and wR = 0.1053 for 10265 observed reflections (I > 2σ(I)). The "naked" Sb113- anion is stable due to the completely sequestered alkali metal cations through ion-ion interactions.     

Deltahedral germanium clusters: insertion of transition-metal atoms and addition of organometallic fragments

Reactions of nine-atom deltahedral clusters of germanium with Ni(COD)2 and/or Ni(PPh3)2(CO)2 in ethylenediamine yielded the Ni-centered heteroatomic 10-atom clusters [Ni@(Ge9Ni-CO)]2- and [Ni@(Ge9Ni-en)]3-, as well as the empty 10-atom heteroatomic cluster [Ge9Ni-CO]3-. A ligand exchange reaction between [Ni@(Ge9Ni-CO)]2- and potassium phenylacetylide produced the organically functionalized species [Ni@(Ge9Ni-CCPh)]3-. The empty cluster [Ge9Ni-CO]3- is a bicapped square antiprism where one of the capping vertexes is the nickel atom. The other three clusters are tricapped trigonal prisms where an additional 10th vertex of monoligated nickel caps a triangular base of the trigonal prism. As a result of this, that base opens up, and the distances within it become nonbonding. This ensures that all atoms of the cluster are equidistant from the central nickel atom, i.e., the cluster is very close to spherical. All species were structurally characterized in crystalline compounds with [K-(2,2,2-crypt)]+ countercations. They were also characterized in solution by mass spectrometry, IR, and 13C NMR.     

Synthesis and Crystal Structure of [K（2,2,2-crypt）]2HP11

[K（2,2,2-crypt]2HP11 has been prepared from the reaction of K3P11 with the mixed ethylenediamine/2,2,2-crypt solution. The crystal structure was determined by singlecrystal X-ray diffraction. The crystal is of tdgonal system, space group P^-3c1 with a = 12.068（2）, b = 12.068（2）, c = 22.319（6）A, V = 2815.0（10）A^3, Dc = 1.384 g/cm^3, C36h73K2N4O12P11, Mr = 1172.85, F（000） = 1232,μ = 0.536 mm^-1, Z= 2, R = 0.0678 and wR = 0.2211 for 1763 observed reflections （I 〉 2σ（I））. In this compound, the P11 cluster has ideal 32-D3 symmetry, and the three-fold axis, corresponds to the crystallographic c axis. The （HP11）^2- anions are stable due to the completely sequestered alkali metal cations through only ion-ion interactions.     

Syntheses; 77Se, 203Tl, and 205Tl NMR; and theoretical studies of the Tl2Se6(6-), Tl3Se6(5-), and Tl3Se7(5-) anions and the X-ray crystal structures of [2,2,2-crypt-Na]4[Tl4Se8].en and [2,2,2-crypt-Na]2[Tl2Se4](infinity)1.en

The 2,2,2-crypt salts of the Tl4Se8(4-) and [Tl2Se4(2-)]infinity1 anions have been obtained by extraction of the ternary alloy NaTl0.5Se in ethylenediamine (en) in the presence of 2,2,2-crypt and 18-crown-6 followed by vapor-phase diffusion of THF into the en extract. The [2,2,2-crypt-Na]4[Tl4Se8].en crystallizes in the monoclinic space group P2(1)/n, with Z = 2 and a = 14.768(3) angstroms, b = 16.635(3) angstroms, c = 21.254(4) angstroms, beta = 94.17(3) degrees at -123 degrees C, and the [2,2,2-crypt-Na]2[Tl2Se4]infinity1.en crystallizes in the monoclinic space group P2(1)/c, with Z = 4 and a = 14.246(2) angstroms, b = 14.360(3) angstroms, c = 26.673(8) angstroms, beta = 99.87(3) degrees at -123 degrees C. The TlIII anions, Tl2Se6(6-) and Tl3Se7(5-), and the mixed oxidation state TlI/TlIII anion, Tl3Se6(5-), have been obtained by extraction of NaTl0.5Se and NaTlSe in en, in the presence of 2,2,2-crypt and/or in liquid NH3, and have been characterized in solution by low-temperature 77Se, 203Tl, and 205Tl NMR spectroscopy. The 1J(203,205Tl-77Se) and 2J(203,205Tl-203,205Tl) couplings of the three anions have been used to arrive at their solution structures by detailed analyses and simulations of all spin multiplets that comprise the 205,203Tl NMR subspectra arising from natural abundance 205,203Tl and 77Se isotopomer distributions. The structure of Tl2Se6(6-) is based on a Tl2Se2 ring in which each thallium is bonded to two exo-selenium atoms so that these thalliums are four-coordinate and possess a formal oxidation state of +3. The Tl4Se8(4-) anion is formally derived from the Tl2Se6(6-) anion by coordination of each pair of terminal Se atoms to the TlIII atom of a TlSe+ cation. The structure of the [Tl2Se4(2-)]infinity1 anion is comprised of edge-sharing distorted TlSe4 tetrahedra that form infinite, one-dimensional [Tl2Se42-]infinity1 chains. The structures of Tl3Se6(5-) and Tl3Se7(5-) are derived from Tl4Se4-cubes in which one thallium atom has been removed and two and three exo-selenium atoms are bonded to thallium atoms, respectively, so that each is four-coordinate and possesses a formal oxidation state of +3 with the remaining three-coordinate thallium atom in the +1 oxidation state. Quantum mechanical calculations at the MP2 level of theory show that the Tl2Se6(6-), Tl3Se6(5-), Tl3Se7(5-), and Tl4Se8(4-) anions exhibit true minima and display geometries that are in agreement with their experimental structures. Natural bond orbital and electron localization function analyses were utilized in describing the bonding in the present and previously published Tl/Se anions, and showed that the Tl2Se6(6-), Tl3Se6(5-), Tl3Se7(5-), and Tl4Se8(4-) anions are electron-precise rings and cages.     

Charged molecular alloys: synthesis and characterization of the binary anions Pd(7)As(16)(4-) and Pd(2)As(14)(4-)

Pd(PCy(3))(2) (Cy = cyclohexyl) reacts with As(7)(3-) in en/tol solvent mixtures to give Pd(2)As(14)(4-) (2) and Pd(7)As(16)(4-) (4) as the [K(2,2,2-crypt)](+) salts. The anions were characterized by EDX, ESI-MS, and single-crystal X-ray diffraction. Anion 2 formally contains two norbornadiene-like As(7)(5-) groups bound to square-planar Pd(III) centers linked by a Pd-Pd bond (d(Pd)(-)(Pd) = 2.7144(6) A). Anion 4 has a highly distorted capped trigonal prismatic Pd(7) core stabilized by 2 As(5)(1-), 2 As(2)(2-), and 2 As(3-) anions. The 6 Pd(I) ions are in distorted 5-coordinate environments whereas the lone Pd(II) ion is square planar. Complexes 2 and 4 are rare examples of organic-free, homoleptic transition metal anions containing group 15 elements, and they represent an emerging class of charged "molecular alloys".