Ga2Br2R2 und Ga3I2R3 [R = C(SiMe3)3] — zwei neue elementorganische Galliumsubhalogenide mit einer bzw. zwei Ga‐Ga‐Bindungen

Ga₂Br₂R₂ and Ga₃I₂R₃ [R = C(SiMe₃)₃] — Two New Organoelement Subhalides of Gallium Containing One or Two Ga‐Ga Single Bonds The oxidation of the tetrahedral tetragallium cluster Ga₄[C(SiMe₃)₃]₄ ( 1 ) with elemental bromine in the presence of AlBr₃ yielded the corresponding gallium subhalide Ga₂Br₂R₂ [ 4 , R = C(SiMe₃)₃], which remains monomer even in the solid state and in which the Ga^II atoms are connected by a short Ga‐Ga single bond [243.2(2) pm]. The analogous diiodide Ga₂I₂R₂ ( 3 ), which was obtained on a similar route by our group only recently, did not react with lithium tert‐butanolate by substitution as originally expected. Instead, partial disproportionation occurred with the formation of the trigallium diiodide Ga₃I₂R₃ ( 6 ), in which three Ga atoms are connected by two Ga‐Ga single bonds (255.1 pm on average). Both terminal Ga atoms have a coordination number of four owing to the bridging function of both iodine atoms, while the inner one which has an oxidation number of +1 remains coordinatively unsaturated. An average oxidation state of 1.66 resulted for all atoms of the chain. The Ga^III compound {[GaI(R)(OCMe₃)(OH)]Li}₂ ( 7 ) was isolated as the second product of the disproportionation. It is a dimer in the solid state via Li‐O bridges and shows a hindered rotation of its tert‐butyl group.     

Reaktionen der Digalliumverbindung R2Ga–GaR2 [R = CH(SiMe3)2] mit Wasser und Carbonsäuren – Synthese von μ‐Hydroxo‐μ‐carboxylatodigallium‐Verbindungen unter Erhalt der Ga–Ga‐Bindungen

Treatment of the digallium compound R₂Ga–GaR₂ [ 1 , R = CH(SiMe₃)₂] with a broad variety of functionalized carboxylic acids in the presence of water yielded μ‐hydroxo‐μ‐carboxylatodigallium compounds ( 2 – 10 ) containing intact Ga–Ga bonds in high to moderate yields. The compounds form dimeric formula units in which the unsupported Ga–Ga bonds are bridged by two hydroxo and two carboxylato ligands. Each gallium atom is terminally coordinated by a bulky alkyl group. NMR spectroscopy revealed mixtures of two isomeric compounds in solution in all cases. The second component may show a different bridging mode with each Ga–Ga bond bridged by a bidentate carboxylato ligand to form Ga₂O₂C five‐membered heterocycles.     

Die Reaktion des Digalliumsubiodids R(I)Ga‐Ga(I)R [R = C(SiMe3)3] mit Lithium‐diphenylphosphanid – radikalische Öffnung der Ga‐Ga‐Bindung

The Reaction of the Digallium Subiodide R(I)Ga‐Ga(I)R [R = C(SiMe₃)₃] with Lithium Diphenylphosphanide – Radical Cleavage of the Ga‐Ga Bond The easily available organoelement digallium(II) subiodide R(I)Ga‐Ga(I)R ( 1 ) [R = C(SiMe₃)₃] reacted with two equivalents of lithium diphenylphosphanide in toluene by the replacement of both iodine atoms by two phosphanido groups. The product, [R(H)Ga‐P(C₆H₅)₂]₂ ( 2 ), contains a four‐membered Ga₂P₂ heterocycle without direct Ga‐Ga bonding interactions and the gallium atoms exclusively in an oxidation state of +III. They are attached to hydrogen atoms, which may result from a reaction of a reactive intermediate with the solvent.     

A Ga‐MIL‐53‐type Framework based on 1,4‐Phenylenediacetate Showing Subtle Flexibility

The new MOF Ga‐MIL‐53‐PDA [Ga(OH)(O₂C‐C₈H₈‐CO₂)] · H₂O ( 1 ) was synthesized by a hydrothermal reaction of gallium nitrate, 1,4‐phenylenediacetic acid (H₂PDA) and sodium hydroxide at 100 °C for 24 h. The product is a structural analogue of the archetypical MIL‐53 framework. Its crystal structure was determined by Rietveld refinement of powder X‐ray diffraction (PXRD) data. Furthermore 1,4‐phenylenedipropionic acid (H₂PDP) was employed for further synthesis, which resulted in the dense layered coordination polymers [Ga₂(OH)₄(O₂C‐C₁₀H₁₂‐CO₂)] ( 2 ) and [Ga(OH)(O₂C‐C₁₀H₁₂‐CO₂)] ( 3 ), for which accurate structural models could be established. All compounds were fully characterized and tested regarding potential breathing behavior. Most remarkably, Ga‐MIL‐53‐PDA showed a subtle flexibility upon de/‐rehydration also confirming its porosity, but no drastic structural changes were observed.     

Hydrogallierungsreaktionen mit den Monoalkinen H5C6‐C≡C‐SiMe3 und H5C6‐C≡C‐CMe3 – cis/trans‐Isomerie und Substituentenaustausch

Hydrogallation Reactions Involving the Monoalkynes H₅C₆‐C≡C‐SiMe₃ and H₅C₆‐C≡C‐CMe₃ – cis/trans Isomerisation and Substituent Exchange Phenyl‐trimethylsilylethyne, H₅C₆‐C≡C‐SiMe₃, reacted with different dialkylgallium hydrides, R₂Ga‐H (R = Me, Et, nPr, iPr, tBu), by the addition of one Ga‐H bond to its C≡C triple bond (hydrogallation). The gallium atoms attacked selectively those carbon atoms, which were also attached to trimethylsilyl groups. The cis arrangement of Ga and H across the resulting C=C double bonds resulted only for the sterically most shielded di(tert‐butyl)gallium derivative, while in all other cases spontaneous cis/trans rearrangement occurred with the quantitative formation of the trans addition products. The diethyl compound Et₂Ga‐C(SiMe₃)=C(H)‐C₆H₅ ( 2 ) gave by substituent exchange the secondary products EtGa[C(SiMe₃)=C(H)‐C₆H₅]₂ ( 7 , Z,Z) and Ga[C(SiMe₃)=C(H)‐C₆H₅]₃ ( 8 ). Interestingly, compound 8 has two alkenyl groups with a Z configuration, while the third C=C double bond has the cis arrangement of Ga and H (E configuration). The reversibility of the cis/trans isomerisation of hydrogallation products was observed for the first time. tert‐Butyl‐phenylethyne gave the simple addition product, R₂Ga(C₆H₅)=C(H)‐CMe₃ ( 9 ), only with di(n‐propyl)gallium hydride.     

8‐Amidoquinoline, 8‐(Trialkylsilylamido)quinoline, 2‐Pyridylmethylamide,and (2‐Pyridylmethyl)(trialkylsilyl)amide Complexes of Gallium

Lithium 8‐amidoquinoline ( 1 ) and lithium 8‐(trialkylsilylamido)quinoline [SiMe₂tBu ( 2 ), SiiPr₃ ( 3 )] react with dimethylgallium chloride to the metathesis products dimethylgallium 8‐amidoquinoline ( 4 ) as well as dimethylgallium 8‐(trialkylsilylamido)quinoline [SiMe₂tBu ( 5 ), SiiPr₃ ( 6 )]. The gallium atoms are in distorted tetrahedral environments. During the synthesis of 5 , orange dimethylgallium 2‐butyl‐8‐(tert‐butyldimethylsilylamido)quinoline ( 7 ) was found as by‐product. The metathesis reactions of Me₂GaCl with LiN(R)CH₂Py (Py = 2‐pyridyl) yield the corresponding 2‐pyridylmethylamides Me₂Ga‐N(H)CH₂Py ( 8 ), Me₂Ga‐N(SiMe₂tBu)CH₂Py ( 9 ) and Me₂Ga‐N(SiiPr₃)CH₂Py ( 10 ). In these complexes the gallium atoms show a distorted tetrahedral coordination sphere. However, derivative 8 crystallizes dimeric with bridging amido units whereas in 9 and 10 the 2‐pyridylmethylamido moieties act as bidentate ligands leading to monomeric molecules.     

Crystallographic report: Fluoro‐bis‐iso‐propyl‐(2,4,6‐tris‐iso‐propylphenyl)‐ silane,i‐Pr2(2,4,6‐i‐Pr3C6H2)SiF

Owing to steric congestion in i‐Pr₂(2,4,6‐i‐Pr₃C₆H₂)SiF, the geometry at the Si atom deviates slightly from ideal tetrahedral geometry with an increased C? Si? C angle of 119.02(9)° and elongated Si? C and Si? F bond distances. Copyright © 2005 John Wiley & Sons, Ltd.     

New Ga/N‐based Active Lewis Pairs,Trifunctional Ga–Ga Compounds,Reactions with Cyanamide and Dual Insertion of Isocyanate

Hydrogallation of Me₃Si–C≡C–NR'₂ with R₂Ga–H (R = tBu, CH₂tBu, iBu) yielded Ga/N‐based active Lewis pairs, R₂Ga–C(SiMe₃)=C(H)–NR'₂ ( 7 ). The Ga and N atoms adopt cis‐positions at the C=C bonds and show weak Ga–N interactions. tBu₂GaH and Me₃Si–C≡C–N(C₂H₄)₂NMe afforded under exposure of daylight the trifunctional digallium(II) compound [MeN(C₂H₄)₂N](H)C=C(SiMe₃)Ga(tBu)–Ga(tBu)C(SiMe₃)=C(H)[N(C₂H₄)₂NMe] ( 8 ), which results from elimination of isobutene and H₂ and Ga–Ga bond formation. 8 was selectively obtained from the ynamine and [tBu(H)Ga–Ga(H)tBu]₂[HGatBu₂]₂. 7a (R = tBu; NR'₂ = 2,6‐Me₂NC₅H₈) and H₈C₄N–C≡N afforded the adduct tBu₂Ga‐C(SiMe₃)=C(H)(2,6‐Me₂NC₅H₈) · N≡C–NC₄H₈ ( 11 ) with the nitrile bound to gallium. The analogous ALP with harder Al atoms yielded an adduct of the nitrile dimer or oligomers of the nitrile at room temperature. The reaction of 7a with Ph–N=C=O led to the insertion of two NCO groups into the Ga–C_vinyl bond to yield a GaOCNCN heterocycle with Ga bound to O and N atoms ( 12 ).     

Bis(arylimido) Molybdenum(VI) Amidinate and Guanidinate Complexes; Molecular Structures of [(ArN)2MoMe{N(Cy)C[N(i‐Pr)2]N(Cy)}] (Ar = 2,6‐i‐Pr2C6H3; Cy = Cyclohexyl) and [(2,6‐i‐Pr2C6H3N)2MoCl2] · [NH=C(C6H5)CH(SiMe3)2]

The reaction of [(ArN)₂MoCl₂] · DME (Ar = 2,6‐i‐Pr₂C₆H₃) ( 1 ) with lithium amidinates or guanidinates resulted in molybdenum(VI) complexes [(ArN)₂MoCl{N(R¹)C(R²)N(R¹)}] (R¹ = Cy (cyclohexyl), R² = Me ( 2 ); R¹ = Cy, R² = N(i‐Pr)₂ ( 3 ); R¹ = Cy, R² = N(SiMe₃)₂ ( 4 ); R¹ = SiMe₃, R² = C₆H₅ ( 5 )) with five coordinated molybdenum atoms. Methylation of these compounds was exemplified by the reactions of 2 and 3 with MeLi affording the corresponding methylates [(ArN)₂MoMe{N(R¹)C(R²)N(R¹)}] (R¹ = Cy, R² = Me ( 6 ); R¹ = Cy, R² = N(i‐Pr)₂ ( 7 )). The analogous reaction of 1 with bulky [N(SiMe₃)C(C₆H₅)C(SiMe₃)₂]Li · THF did not give the corresponding metathesis product, but a Schiff base adduct [(ArN)₂MoCl₂] · [NH=C(C₆H₅)CH(SiMe₃)₂] ( 8 ) in low yield. The molecular structures of 7 and 8 are established by the X‐ray single crystal structural analysis.     

Bis(dimethyl sulfoxide‐S)tetrakis(μ‐p‐hydroxybenzoato‐O:O′)dirhodium(II)–tetrakis(μ‐butyrato‐O:O′)bis(dimethyl sulfoxide‐S)dirhodium(II) cocrystal ethanol disolvate

The title structure, [Rh₂(C₇H₅O₃)₄(C₂H₆OS)₂]·[Rh₂(C₄H₇­O₂)₄(C₂H₆OS)₂]·2C₂H₆O, contains two discrete neutral Rh–Rh dimers cocrystallized as the ethanol disolvate. Each dimer is situated on an inversion center. The butyrate chain displays disorder in one C‐atom position. In each dimer, the di­methyl sulfoxide ligand (dmso) is bound via S, as expected. The ethanol is a hydrogen‐bond acceptor for one p‐hydroxy­benzoate hydroxyl group and acts as a hydrogen‐bond donor to the dmso O atom of a neighboring p‐hydroxy­benzoate dirhodium complex. A third hydrogen bond is formed from the other p‐hydroxy­benzoate hydroxyl group to the dmso O atom of a butyrate–dirhodium complex.     

Di‐μ‐hydro­xo‐bis­(diiso­propyl­gallium)–1,4,8,11‐tetra­methyl‐1,4,8,11‐tetra­aza­cyclo­tetra­decane (1/1)

The hydro­lysis product [Ga₂(C₃H₇)₄(OH)₂]·C₁₄H₃₂N₄, derived from the tetrakis­(triiso­propyl­gallium)–1,4,8,11‐tetra­methyl‐1,4,8,11‐tetra­aza­cyclo­tetra­decane (1/1) adduct, consists of a centrosymmetric [ⁱPr₂Ga(μ‐OH)]₂ unit hydrogen bonded through the hydroxyl group to a nitro­gen on an adjacent centrosymmetric 1,4,8,11‐tetra­methyl‐1,4,8,11‐tetra­aza­cyclo­tetra­decane molecule, resulting in the generation of a molecular chain through the crystal.     

A novel two‐dimensional cadmium(II) complex: poly[diaquatris(μ4‐cyclohexane‐1,4‐dicarboxylato)bis[2‐(pyridin‐4‐yl)‐1H‐benzimidazole]tricadmium(II)

The title compound, [Cd₃(C₈H₁₀O₄)₃(C₁₂H₉N₃)₂(H₂O)₂]_n or [Cd₃(chdc)₃(4‐PyBIm)₂(H₂O)₂]_n, was synthesized hydrothermally from the reaction of Cd(CH₃COO)₂·2H₂O with 2‐(pyridin‐4‐yl)‐1H‐benzimidazole (4‐PyBIm) and cyclohexane‐1,4‐dicarboxylic acid (1,4‐chdcH₂). The asymmetric unit consists of one and a half Cd^II cations, one 4‐PyBIm ligand, one and a half 1,4‐chdc²⁻ ligands and one coordinated water molecule. The central Cd^II cation, located on an inversion centre, is coordinated by six carboxylate O atoms from six 1,4‐chdc²⁻ ligands to complete an elongated octahedral coordination geometry. The two terminal rotationally symmetric Cd^II cations each exhibits a distorted pentagonal–bipyramidal geometry, coordinated by one N atom from 4‐PyBIm, five O atoms from three 1,4‐chdc²⁻ ligands and one O atom from an aqua ligand. The 1,4‐chdc²⁻ ligands possess two conformations, i.e.e,e‐trans‐chdc²⁻ and e,a‐cis‐chdc²⁻. The cis‐1,4‐chdc²⁻ ligands bridge the Cd^II cations to form a trinuclear {Cd₃}‐based chain along the b axis, while the trans‐1,4‐chdc²⁻ ligands further link adjacent one‐dimensional chains to construct an interesting two‐dimensional network.     

Multiple Ga−Ga Bonding Character in Na2[Ga(GaTrip2)3], and a Comparison with Neutral Ga(GaTrip2)3 (Trip=2,4,6-iPr3C6H2)

Delocalized over the Ga ₄ framework , the two electrons are lost in the oxidation of Na₂[Ga(GaTrip₂)₃] to Ga(GaTrip₂)₃. This leads to a lengthening of the Ga−Ga bond by about 0.08 Å. Ar=Trip=2,4,6-iPr₃C₆H₂.     

{μ‐N,N′‐Bis[3‐(dimethyl­amino)prop­yl]­oxamidato(2–)‐κ6N,N′,O′:N′′,N′′′,O}­bis­[(1H‐imidazole‐κN3)(methanol‐κO)copper(II)] bis­(perchlorate)

The structure of the title compound, [Cu₂(C₁₂H₂₄N₄O₂)(C₃H₄N₂)₂(CH₄O)₂](ClO₄)₂ or [Cu₂(dmoxpn)(HIm)₂(CH₃OH)₂](ClO₄)₂, where dmoxpn is the dianion of N,N′‐bis­[3‐(dimethyl­amino)prop­yl]oxamide and HIm is imidazole, consists of a centrosymmetric trans‐oxamidate‐bridged copper(II) binuclear cation, having an inversion centre at the mid‐point of the central C—C bond, and two perchlorate anions. The Cu^II atom has square‐pyramidal coordination geometry involving two N atoms and an O atom from the dmoxpn ligand, an N atom from an imidazole ring, and an O atom from a methanol mol­ecule. The crystal structure is stabilized by O—H⋯O, N—H⋯O and C—H⋯O hydrogen bonds and imidazole π–π stacking inter­actions to form a three‐dimensional supra­molecular array.     

Lutetium‐Methanediide‐Alkyl Complexes: Synthesis and Chemistry

The first four‐coordinate methanediide/alkyl lutetium complex (BODDI)Lu₂(CH₂SiMe₃)₂(μ₂‐CHSiMe₃)(THF)₂ (BODDI=ArNC(Me)CHCOCHC(Me)NAr, Ar=2,6‐iPr₂C₆H₃) ( 1 ) was synthesized by a thermolysis methodology through α‐H abstraction from a Lu–CH₂SiMe₃ group. Complex 1 reacted with equimolar 2,6‐iPrC₆H₃NH₂ and Ph₂C?O to give the corresponding lutetium bridging imido and oxo complexes (BODDI)Lu₂(CH₂SiMe₃)₂(μ₂‐N‐2,6‐iPr₂C₆H₃)(THF)₂ ( 2 ) and (BODDI)Lu₂(CH₂SiMe₃)₂(μ₂‐O)(THF)₂ ( 3 ). Treatment of 3 with Ph₂C?O (4 equiv) caused a rare insertion of Lu–μ₂‐O bond into the C?O group to afford a diphenylmethyl diolate complex 4 . Reaction of 1 with PhN=C?O (2 equiv) led to the migration of SiMe₃ to the amido nitrogen atom to give complex (BODDI)Lu₂(CH₂SiMe₃)₂‐μ‐{PhNC(O)CHC(O)NPh(SiMe₃)‐κ³N,O,O}(THF) ( 5 ). Reaction of 1 with tBuN?C formed an unprecedented product (BODDI)Lu₂(CH₂SiMe₃){μ₂‐[η²:η²‐tBuNC(=CH₂)SiMe₂CHC?NtBu‐κ¹N]}(tBuN?C)₂ ( 6 ) through a cascade reaction of N?C bond insertion, sequential cyclometalative γ‐(sp³)‐H activation, C?C bond formation, and rearrangement of the newly formed carbene intermediate. The possible mechanistic pathways between 1 , PhN?C?O, and tBuN?C were elucidated by DFT calculations.     

Crystallographic report: [(η5‐C5H5)Fe(CO)2]2Ga3Cl3(OSiMe2OSiMe2O)2: a diiron complex of a tetracyclic trigallasiloxane

The structure of the penta‐metallic diiron trigallasiloxane, [(η⁵‐C₅H₅)Fe(CO)₂]₂Ga₃Cl₃(OSiMe₂ OSiMe₂O)₂, reveals two distinct gallium coordination environments and Fe? Ga bond lengths (2.3258(6) Å), consistent with bonding of the iron centres to four‐coordinate gallyl ligands. Copyright © 2004 John Wiley & Sons, Ltd.     

Synthese,Struktur und Reaktivität von η3‐1,2‐Diphosphaallylkomplexen sowie von [{(η5‐C5H5)(CO)2W–Co(CO)3}{μ‐AsCH(SiMe3)2}(μ‐CO)]

Syntheses, Structure and Reactivity of η³‐1,2‐Diphosphaallyl Complexes and [{(η⁵‐C₅H₅)(CO)₂W–Co(CO)₃}{μ‐AsCH(SiMe₃)₂}(μ‐CO)] Reaction of ClP=C(SiMe₂iPr)₂ ( 3 ) with Na[Mo(CO)₃(η⁵‐C₅H₅)] afforded the phosphavinylidene complex [(η⁵‐C₅H₅)(CO)₂Mo=P=C(SiMe₂iPr)₂] ( 4 ) which in situ was converted into the η¹‐1,2‐diphosphaallyl complex [η⁵‐(C₅H₅)(CO)₂Mo{η³‐tBuPPC(SiMe₂iPr)₂] ( 6 ) by treatment with the phosphaalkene tBuP=C(NMe₂)₂. The chloroarsanyl complexes [(η⁵‐C₅H₅)(CO)₃M–As(Cl)CH(SiMe₃)₂] [where M = Mo ( 9 ); M = W ( 10 )] resulted from the reaction of Na[M(CO)₃(η⁵‐C₅H₅)] (M = Mo, W) with Cl₂AsCH(SiMe₃)₂. The tungsten derivative 10 and Na[Co(CO)₄] underwent reaction to give the dinuclear μ‐arsinidene complex [(η⁵‐C₅H₅)(CO)₂W–Co(CO)₃{μ‐AsCH(SiMe₃)₂}(μ‐CO)] ( 11 ). Treatment of [(η⁵‐C₅H₅)(CO)₂Mo{η³‐tBuPPC(SiMe₃)₂}] ( 1 ) with an equimolar amount of ethereal HBF₄ gave rise to a 85/15 mixture of the saline complexes [(η⁵‐C₅H₅)(CO)₂Mo{η²‐tBu(H)P–P(F)CH(SiMe₃)₂}]BF₄ ( 18 ) and [Cp(CO)₂Mo{F₂PCH(SiMe₃)₂}(tBuPH₂)]BF₄ ( 19 ) by HF‐addition to the PC bond of the η³‐diphosphaallyl ligand and subsequent protonation ( 18 ) and/or scission of the PP bond by the acid ( 19 ). Consistently 19 was the sole product when 1 was allowed to react with an excess of ethereal HBF₄. The products 6 , 9 , 10 , 11 , 18 and 19 were characterized by means of spectroscopy (IR, ¹H‐, ¹³C{¹H}‐, ³¹P{¹H}‐NMR, MS). Moreover, the molecular structures of 6 , 11 and 18 were determined by X‐ray diffraction analysis.     

Structures and properties of (H2GaN3)n (n = 1–4) clusters: A DFT study

Computations on the systems of (H₂GaN₃)_n (n = 1–4) are performed using the density functional theory (DFT)/B3LYP method with different basis sets. (H₂GaN₃)₂ possessing D_2h symmetry is found to exhibit the planar Ga₂N₂ ring structure. (H₂GaN₃)₃ involving a six‐membered Ga₃N₃ ring is found to exhibit two minima with very similar binding energies (ca. −235 ∼ −231 kJ · mol⁻¹). One minimum is the newly found boat‐like conformation possessing C_s symmetry. Another minimum possessing C_3v symmetry is the chair‐like conformation. (H₂GaN₃)₄ occurs in several structures with Ga₄N₄ eight‐membered ring structures that correspond to minima with slight energy differences among them. The structural changes of the clusters are large compared with the monomer. Frequency calculations are carried out on each optimized structure, and their infrared (IR) spectra are discussed. Thermodynamic properties demonstrate that the systems of H₂GaN₃ occur at dimer–trimer–tetramer equilibrium, and the trimer is the main component. © 2004 Wiley Periodicals, Inc. Int J Quantum Chem, 2004     

catena‐Poly­[[di‐μ‐benzoato‐κ4O:O′‐disilver(I)]‐μ‐N,N′‐bis(2‐fluoro­benzyl­idene)­butane‐1,4‐di­amine‐κ2N:N′]

The title complex, [Ag₂(C₇H₅O₂)₂(C₁₈H₁₈F₂N₂)]_n, is a dinuclear silver(I) compound with one inversion centre between pairs of Ag atoms and another at the mid‐point of the central C—C bond in the butane‐1,4‐diamine moiety. Each of the smallest repeat units consists of two silver(I) cations, two benzoate anions and one N,N′‐bis(2‐fluorobenzyl­idene)­butane‐1,4‐di­amine Schiff base ligand. Each Ag^I ion is three‐coordinated in a trigonal configuration by two O atoms from two benzoate anions and one N atom from a Schiff base ligand. The di‐μ‐benzoato‐disilver(I) moieties are linked by the bridging Schiff base ligand, giving zigzag polymeric chains with an [–Ag⋯Ag—N—C—C—C—C—N–]_n backbone running along the b axis.     

Bis(2,6‐diamino‐1H‐purin‐3‐ium) di‐μ‐croconato‐κ3O,O′:O′′;κ3O:O′,O′′‐bis[tetraaqua(croconato‐κ2O,O′)neodymium(III)]

The structure of the ionic title compound, (C₅H₇N₆)₂[Nd₂(C₅O₅)₄(H₂O)₈], consists of anionic dimers built around an inversion centre and is made up of an Nd^III cation, two croconate (croco) dianions and four water molecules (plus their inversion images), with two noncoordinated symmetry‐related 2,6‐diamino‐1H‐purin‐3‐ium (Hdap⁺) cations providing charge balance. Each Nd^III atom is bound to nine O atoms from four water and three croco units. The coordination polyhedron has the form of a rather regular monocapped square antiprism. The croconate anions are regular and the Hdap⁺ cation presents a unique, thus far unreported, protonation state. The abundance of hydrogen‐bonding donors and acceptors gives rise to a complex packing scheme consisting of dimers interlinked along the three crystallographic directions and defining anionic `cages' where the unbound Hdap⁺ cations lodge, linking to the mainframe via (N—H)_Hdap...O_water/croco and (O—H)_water...N_Hdap interactions.