Synthesis and Structural/Theoretical (DFT) Analysis of the Geometrically Unprecedented Au–Pt Cluster, Pt7(μ 2-CO)8(PPh3)4(μ 4-AuPPh3)2: Structure-to-Synthesis Appraisal Concerning Its Formation

In ongoing attempts to synthesize nanosized gold-platinum carbonyl phosphine clusters either directly or indirectly by initially obtaining intermediate-sized ones as potential precursors, the neutral Au–Pt CO/PR₃-ligated cluster, Pt₇( ₂-CO)₈ (PPh₃)₄( ₄-AuPPh₃)₂ (1), was isolated and characterized by low-temperature CCD X-ray diffraction, IR, and mass spectrometric measurements. The heretofore unknown 9-atom metal architecture of the Au₂Pt₇ core may be envisioned as a Pt₇ adduct of a Pt₄ butterfly and an edge-opened Pt₃ triangle that is additionally linked by two tetracapping AuPPh₃ units. Each of the two butterfly-hinged (basal) Pt atoms is connected to two of the three edge-opened triangular Pt atoms thereby giving rise to an essentially coplanar Pt₅ fragment consisting of three edge-fused bonding triangles; addition of two AuPPh₃ units to the Pt₇ adduct completes the Au₂Pt₇ framework via formation of the two symmetry-equivalent square-pyramidal ( ₄-Au)Pt₄ moieties, each resulting from the tetracapping of a AuPPh₃ unit to the central Pt₃ triangle of the coplanar Pt₅ fragment and to one of the two out-of-plane wingtip Pt atoms. Six PPh₃ ligands are coordinated to the two Au atoms, the two wingtip Pt atoms of the Pt₄butterfly-shaped fragment, and the two outer Pt atoms of the edge-opened Pt₃ triangle. Four of the eight doubly bridging ₂-COs link the four edges connecting the two out-of-plane wingtip Pt atoms with the two hinged (basal) Pt atoms, while the other four ₂-COs span four of the five Pt–Pt bonding edges of the coplanar Pt₅ fragment (i.e., the fifth Pt–Pt bonding edge is spanned by the two out-of-plane wingtip Pt atoms). The resulting molecular configuration (without P-attached phenyl substituents) possesses crystallographic C₂ (2) and pseudo-C_2v symmetry. An optimized geometry of the PH₃- and PMe₃-models of 1, obtained from gradient-corrected (scalar-relativistic) DFT calculations is in reasonably good agreement with the crystallographically determined geometry of 1.A structure-to-synthesis approach is presented as part of extensive but unsuccessful efforts to design a high-yield reproducible preparative route to 1 in order to enable physical/chemical studies as well as to utilize it as a preformed cluster for further PPh₃/CO deligation reactions.     

Half-sandwich metal diselenolate complexes Cp#M(NO)(SePh)2 (M = Mo or W; Cp# = Cp or MeCp) as ligands. Synthesis of selenolate-bridged heterobimetallic compounds

The reactions of half-sandwich diselenolate Mo and W complexes Cp^#M(NO)(SePh)₂ (M = Mo; Cp^# = Cp (1a), MeCp (1b); M = W; Cp^# = Cp (1c)) with (Norb)Mo(CO)₄, Ni(COD)₂ and Fe(CO)₅ have been investigated. Treatment of (1a), (1b) and (1c) with (Norb)Mo(CO)₄ in PhMe gave the bimetallic complexes: CpMo(NO)(-SePh)₂Mo(CO)₄ (2a), MeCpMo(NO)(-SePh)₂Mo(CO)₄ (2b) and CpW(NO)(-SePh)₂Mo(CO)₄ (2c) in moderate yields. Irradiation of (1a) and (1c) in the presence of Fe(CO)₅ gave heterobimetallic complexes CpMo(CO)(-SePh)₂Fe(CO)₃ (3a) and CpW(NO)(-SePh)₂Fe(CO)₃ (3c). Ni(COD)₂ reacts with two equivalents of (1a), (1b) and (1c) to give [CpMo(NO)(-SePh)₂]₂Ni (4a), [MeCpMo(NO)(-SePh)₂]₂Ni (4b) and [CpW(NO)(-SePh)₂]₂Ni (4c) in good yields. The new heterobimetallic complexes were characterized by i.r., ¹H-n.m.r., ¹³C-n.m.r. and EI-MS spectroscopy.     

The synthesis and structure of the [2.2]paracyclophane cluster Ru6C(CO)13(μ 3-η 2:η 2:η 2-C16H16)(PPh3) and a study of the 1H-n.m.r. spectra of [2.2]paracyclophane and benzene clusters

Summary The [2.2]paracyclophane cluster, Ru₆C(CO)₁₄( ₃- ^{2 2 2}-C₁₆H₁₆) (1), undergoes reaction with Me₃NO and triphenylphosphine to yield Ru₆C(CO)₁₃( ₃- ^{2 2 2}-C₁₆H₁₆)(PPh₃) (2), which may also be produced from (1) by thermolysis with PPh₃ in THF. Compound (2) has been fully characterized in solution by spectroscopy and in the solid state by a single crystal X-ray diffraction analysis at 277 K, and its structure is compared with that of the parent cluster, (1). Using the same synthetic procedures, the tricyclohexylphosphine analogue, Ru₆C(CO)₁₃( ₃- ^{2 2 2}-C₁₆H₁₆)(PCy₃) (3), has also been prepared and characterized spectroscopically. A comparison of the chemical shifts of the 577-01 protons in the ¹H-n.m.r. spectra of compounds (1)–(3) together with a variety of other [2.2]paracyclophane and benzene clusters has been made.     

Synthesis and Structure of a Novel Mg6 Cluster Molecule Mg6(μ3-OH)2(μ3-Br)2(μ-Br)8(THF)8

A novel Mg₆ cluster molecule with the formula of Mg₆( ₃-OH)₂( ₃-Br)₂(-Br)₈(THF)₈ (1) has been isolated in 38% yield from a reaction of the Grignard reagent, 2-naphthyl-Mg-Br with BBr₃ in THF. The structure of 1, determined by a single-crystal X-ray diffraction analysis, contains two Mg₃ triangles linked together by two bridging bromide ligands. Within each Mg₃ triangle, one hydroxide and one bromide ligand function as triply bridging ligands capping both sides of the Mg₃ triangle. The coordination geometry around each Mg(II) ion is approximately octahedral. NMR studies revealed that compound 1 is highly fluxional in solution.     

Symmetric binuclear complexes with an ‘end-off’ compartmental Schiff base ligand

Four binuclear transition metal(II) complexes: [Co₂L(-Cl)Cl₂] · 2H₂O, [Ni₂L(-Cl)Cl₂(H₂O)₂] · 2H₂O, [Cu₂L(-Cl)Cl₂] · 2H₂O and [Zn₂L(-Cl)Cl₂] · 2H₂O, where LH is the binucleating ligand 2,6-diformyl-4-methylphenol bis(2-hydrazino benzothiazole), were prepared. Based on the i.r. spectra, elemental analysis, conductivity measurements and thermal analysis, we propose that these complexes contain an endogenous phenoxide bridge and an exogenous chloride bridge. Magnetic and spectral data supports the existence of a weak antiferromagnetic interaction between the metal ions, and octahedral for Ni^II and a square pyramidal environment for remaining complexes. The compounds show significant growth inhibitory activity against the fungi, Aspergillus niger and Candida albicans, as compared to antibacterial activity against Bacillus cirroflagellosus and Pseudomonas auregenosa.     

New cobalt trimethylacetate complexes with pyridine

The reaction of the tetranuclear trimethylacetate complex Co₄(₃-OH)₂(-OOCCMe₃)₄(²-OOCCMe₃)₂(EtOH)₆ with pyridine in acetonitrile was studied. Two new compounds, viz., the hexanuclear cobalt(ii) complex Co₆py₄(₃-OH)₂(-OOCCMe₃)₁₀ (25% yield) and the unusual ionic compound [Co₃py₃(₃-O)(-OOCCMe₃)₆]⁺[Co₄py(₄-O)(-OOCCMe₃)₇]^– (5% yield), were prepared. The structures of the new compounds were established by X-ray diffraction analysis.     

Isocyanide complexes of rhodium,part 31,2. Tetrakisisocyanide species four- and five-coordinate mixed isocyanide-tertiary phosphine complexes,and some oxidative-additions

Summary The complexes [Rh(CNR)₄][PF₆] (R = Et, C₆H₁₁,-NH₂C₆H₄ or I-C₁₀H₇),trans-[Rh(CNR)₂(PRR ₂ ^" )₂][PF₆] (R = R = Ph, R = Et, C₆H₁₁, -NH₂C₆H₄ or 1-C₁₀H₇; R= Me, R = Ph or R= Ph, R= Me, R= 1-C₁₀H₇) and [Rh(CNR)₃(PPh₃)₂][PF₆] (R = Me, Et or C₆H₁₁) have been prepared by treatment of [Rh(CO)₂Cl]₂ or Rh(CO)(PPh₃)₂Cl with RNC, or of [Rh(CNC₁₀H₇)₄][PF₆] with PRR₂ (R, R = Me, Ph). Addition of -ClC₆H₄NC to [Rh(CNEt)₂(PPh₃)₂][PF₆] gives [Rh(CNEt)₂(CNC₆H₄Cl-)(PPh₃)₂][PF₆]. Reactions of [Rh(CNR)₄][PF₆] and [Rh(CNR)₂(PPh₃)₂][PF₆] (R = Me, Et, C₆H₁₁ or 1-C₁₀H₇) with halogens, MeI, McCOCl, CF₃I, HgCl₂ and SO₂, are discussed briefly. The i.r. and¹H n.m.r. spectra show that the products aretrans-[ Rh(CNR)₄XY][PF₆] andtrans-[Rh(CNR)₂(PPh₃)2XY][PF₆].     

Preparation and x-ray structure analysis of [Rh2Cl2(μ-CO)(μ-vdpp)2] [vdpp=H2C=C(PPh2)2]

Summary The complex [Rh₂Cl₂(-CO)(-vdpp)₂] (1) (vdpp=H₂C=C(PPh₂)₂) was prepared by reaction of [Rh₂(CO)₄-(-Cl)₂] with vdpp. When (1) is allowed to stand overnight under an atmosphere of CO without stirringtrans-[Rh₂Cl₂(CO)₂(-vdpp)₂] is formed as a red precipitate in low yields. On rapid addition of CO the tricarbonyl complex [Rh₂(CO)₂(-CO)(-Cl)(-vdpp)₂]-Cl is formed instead. The chemical behaviour of the vdpp-substituted complex (1) is very similar to that of the corresponding dppm-substituted complex [Rh₂(Cl₂-(-CO)(-dppm)₂] (dppm=H₂C(PPh₂)₂). this similarity also extends to the molecular structures of both compounds. Unit cell parameters of (1): space group Pben (Z=8),a=2344.7(5),b=1506.9(7),c=3021.6(9)pm. Rh-Rh 267.4(1) pm.     

Cubane-Type Molybdenum-Zinc or -Cadmium Mixed-Metal Clusters with Diethyldithiophosphate or Nitrilotriacetate Ligands

The reactions of sulfur-bridged clusters, [Mo₃( ₃-S)(-S)₃(-dtp)(dtp)₃(CH₃CN)] (1) in acetonitrile or [Mo₃( ₃-S)(-S)₃(Hnta)₃]^2– (2) in pure water, with zinc or cadmium metal result in the formation of three novel molybdenum-zinc or molybdenum-cadmium mixed-metal clusters, [Zn{( ₃-S)₄Mo₃(-dtp)(dtp)₃(CH₃CN)}₂] (3), [Cd{( ₃-S)₄Mo₃(-dtp)(dtp)₃(CH₃CN)}₂] (4), and [Cd{( ₃-S)₄Mo₃(Hnta)₃}₂]^4– (5), respectively. The X-ray crystal structures of 1·H₂O(1), 3, 4, and [Co(H₂O)₆]₂ 5·22H₂O (5) were determined, and the existence of the sandwich cubane-type cores Mo₃S₄MS₄Mo⁸⁺ ₃ cores (M=Zn, Cd) in 3, 4, and 5 verified. By the change of the ligands, the peak positions at the longest wavelength in the electronic spectra are distinctly different from each other between 4 (856 nm) and 6 (1235 nm). The electronic structures of 3, 4, and 5 have been calculated by Discrete Variational (DV)-X method.     

C-C bond formation at polynuclear metal centers

Studies on C-C bond formation between simple hydrocarbon species such as CH₂, C=CH₂, CH=CH₂, CH₂=CH₂, CH₂=C=CH₂ and CHCH at a diruthenium center suggest that the process is promoted when the dimetal center can readily compensate for the two electrons lost in the formation of the new C-C bond. Thus, whereas -CH₂ and ethene combine only under forcing conditions, the combination of -CH₂ with allene or ethyne, which have additional -electrons available for coordination, occurs readily at room temperature. Likewise, the availability of uncoordinated -electrons in -C=CH₂ allows vinylidene to link rapidly with ethene at room temperature. Alkyne complexes [Ru₂(CO)(-RCCR)(-C₅H₅)₂] (R=CF₃ or Ph) react only under vigorous conditions with additional alkyne to give [Ru₂(CO)(-C₄R₄) (-C₅H₅)₂], but give these same species at room temperature in the presence of acid, shown to be due to the intermediacy of highly reactive 30-electron -vinyl cations. Thermally, alkyne linking proceedsvia three-alkyne species [Ru₂(-C₆R₆)(-C₅H₅)₂] to a four-alkyne complex [Ru₂(-C₈R₈)(-C₅H₅)₂], containing an unprecedented C₈ ligand composed of a C₆ ring with a C₂ tail. Treatment of [Ru₂(CO)(-RCCR)(-C₅H₅)₂] with unsaturated metal fragments gives trimetal complexes such as [Ru₃(CO)₅(₃-CF₃CCCF₃) (-C₅H₅)₂]. The MeCN derivative of this species undergoes unusual linking processes on reaction with additional alkyne to giveinter alia [Ru₃(CO)₃(₃-CCF₃){₃-C₃(CF₃)₃}(-C₅H₅)₂], arising from alkyne cleavage, and [Ru₃(CO)₃{₃-C₄(CF₃)₂(CO₂Me)₂}(-C₅H₅)₂], a closo-pentagonal bipyramidal Ru₃C₄ cluster.     

Basisch substituierte 5,6-Dimethoxy- und 4,5,6-Trimethoxy-benzo[b]thiophene

Zusammenfassung N-substituierte -{5,6-Dimethoxy-benzo[b]thienyl-(3)}-äthylamine, -{4,5,6-Trimethoxy-benzo[b]thienyl-(3)}-äthylamine und -{5,6-Dimethoxy-benzo[b]thienyl-(3)}-propylamine wurden mittels LiAlH₄-Reduktion der entsprechenden von uns schon früher synthetisierten Säureamide hergestellt.

---

N-substituted -{5,6-dimethoxy-benzo[b]thienyl-(3)}-ethylamines, -{4,5,6-trimethoxy-benzo[b]thienyl-(3)}-ethylamines and -{5,6-dimethoxy-benzo[b]thienyl-(3)}-propylamines were prepared by LiAlH₄ reduction of the corresponding amides previously synthesized by us.

     

Cluster synthesis 44. The synthesis and structural characterization of an unusual new high nuclearity platinum-osmium cluster complex,Pt5Os6(CO)25

The reaction of Pt₂Os₄(CO)₁₈ (1) with H₂ in refluxing octane (125°C) yielded the new compound Pt₅Os₆(CO)₂₅ (2), 58%. Compound 2 was characterized by IR, elemental and single crystal X-ray diffraction analyses. Compound 2 contains 11 metal atoms. five platinum, and six osmium. The cluster can be viewed as two fused trigonal bipyramidal clusters that share one platinum vertex. These two clusters are also joined by three metal-metal bonds, and Os(CO)₄ groups bridge two of these three metal-metal bonds. Crystal data for 2·CH₂Cl₂: space group itP1¯ma=12.250(1) Å,b=17.476(4) Å,c=11.89(2) Å,=109.87(1)°,=112.66(1)°,=83.05(2)°,Z=2, 2986 reflections,R=0.033.     

Unsymmetrical dinuclear cobalt and nickel trimethylacetate complexes

The reaction of the dinuclear complex Co₂(-OOCCMe₃)₂(²-OOCCMe₃)₂bpy₂ (1) with the polymer [Co(OH) _n (OOCCMe₃)_2–n ] _x afforded the unsymmetrical dinuclear complex bpyCo₂(₂-O,²-OOCCMe₃)(₂-O,O"-OOCCMe₃)₂(²-OOCCMe₃) (2). The reaction of 2,2"-dipyridylamine with [Co(OH) _n (OOCCMe₃)_2–n ] _x gave rise to the analogous complex [(C₅H₄N)₂NH]Co₂(₂-O,²-OOCCMe₃)(-OOCCMe₃)₂(²-OOCCMe₃) (3). The reaction of complex 1 with Ni₄(₃-OH)₂(-OOCCMe₃)₄(OOCCMe₃)₂(MeCN)₂[²-o-C₆H₄(NH₂)(NHPh)]₂ (4) produced an isostructural heterometallic analog of complex 2 with composition bpyM₂(₂-O,²-OOCCMe₃)(₂-O,O"-OOCCMe₃)₂(²-OOCCMe₃) (5) (M = Co, Ni; Co : Ni = 1 : 1) and the dinuclear heterometallic complex bpy(HOOCCMe₃)M(-OH₂)(-OOCCMe₃)₂M(OOCCMe₃)₂[o-C₆H₄(NH₂)(NHPh)] (6) (M = Co, Ni; Co : Ni = 0.15 : 1.85). Compounds 2 and 5 exhibit ferromagnetic spin-spin exchange interactions.     

Synthesis, Structure, and Thermal Decomposition of Chloropentamminerhodium(III) Hexabromoplatinate(IV)

The binary complex salt [Rh(NH₃)₅Cl][PtBr₆] was synthesized and studied by Xray structural analysis. The crystallographic data are as follows: a = 12.013(2) , b = 8.401(2) , c = 15.999(3) , = 91.13(3)°, V = 1614.3(6) ³, space group P2₁/m, Z = 4, d_x = 3.70 g/cm³, R = 0.086. The thermal decomposition of the salt in a hydrogen atmosphere is shown to produce a Rh_0.5Pt_0.5 solid solution with an FCC cell [a = 3.864(2) . The thermal decomposition of the salt in a helium atmosphere proceeds via the formation of metallic Pt and RhBr₃ and finally results in a mixture of several solid solutions.     

Reactions of 1,4-difeffocenylbuta-1,3-diyne and 1,4-diphenylbut-l-en-3-yne with Ru3(CO)12. Crystal structure of Ru3(CO)8(μ3-η-1-η1-η4-η2-C4Ph2(CH=CHPh)2)

Diyne FcCmCC.CFc (Fc is ferrocenyl) reacts with Ru₃(CO)₁₂ in boiling hexane to yield binuclear complexes Ru₂ and Ru₂(CO)₆(C₄Fc₂(C=CFc)₂C=O) containing ruthenacyclopentadiene and diruthenacycloheptadienone rings, respectively. The isomerism of the complexes is due to the different ways of coupling of the alkyne fragments of the diyne, namely, head-to-head, head-to-tail or tail-to-tail. The reaction of enyne PhC=CCH=CHPh with Ru₃(CO)₁₂ under similar conditions gives isomeric binuclear complexes Ru₂(CO)₆(C₄Ph₂(CH=CHPh)₂) and trinuclear clusters Ru₃(CO)₆(w-CO)₂(C₄Ph₂(CH=CHPh)₂) and Ru₃(CO)₈(₃-,¹-¹-⁴-² C₄Ph₂(CH=CHPh)₂). The structure of the latter was determined by X-ray diffraction analysis. The Ru₃ triangle coordinates eight terminal CO groups and the organic ligand resulting from the head-to-head dimerization of enyne molecules; the ruthenacyclopentadiene moiety is ⁴-coordinated to the Ru(CO)₂ group, and the third ruthenium atom is 2-bound to one of the PhCH=CH groups.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 1261–1267, May, 1996.     

Role of metal center in reactions of polynuclear nickel(ii) and cobalt(ii) trimethylacetates with 8-amino-2,4-dimethylquinoline

The reactions of 8-amino-2,4-dimethylquinoline (L) (1) with polynuclear nickel(ii) and cobalt(ii) hydroxotrimethylacetato complexes under anaerobic conditions were studied. The nonanuclear cluster Ni₉(₄-OH)₃(₃-OH)₃(_n-OOCCMe₃)₁₂(HOOCCMe₃)₄ gave the mononuclear complex Ni(²-L)(²-OOCCMe₃)₂ (2). The tetranuclear complex Ni₄(₃-OH)₂(-OOCCMe₃)₄(²-OOCCMe₃)₂(EtOH)₆ produced the mononuclear complex Ni(²-L)(²-OOCCMe₃)(OOCCMe₃)L (3). At room temperature, the cobalt-containing polynuclear trimethylacetates, viz., the polymer [Co(OH) _n (OOCCMe₃)_2–n ] _x and the tetranuclear complex Co₄(₃-OH)₂(-OOCCMe₃)₄(²-OOCCMe₃)₂(EtOH)₆, were transformed into the trinuclear cobalt(ii) complex Co₃(₃-OH)(-OOCCMe₃)₄(²-L)₂(OOCCMe₃) (4). Meanwhile, at 80 °C these compounds generated the binuclear cobalt(iii) complex Co₂(₂²-(HN)C₉NMe₂)₂(-OOCCMe₃)(L)(OOCCMe₃)₃ (5). The structures of the resulting compounds were established by X-ray diffraction analysis. Compounds 2—4 exhibit the antiferromagnetic spin-spin exchange coupling, whereas compound 5 is diamagnetic.     

The oxidative addition of diphenylphosphine and monophenylphosphine to the electron-rich rhenium-rhenium triple bond. The isolation and characterization of compounds that contain the four-center Re(μ-X)(μ-PR2)Re cluster (X=halide)

Diphenylphosphine oxidatively adds to the ReRe bonds of Re₂ X ₄(-dppm)₂ (X=Cl or Br; dppm=Ph₂PCH₂PPh₂) and Re₂Cl₄(-dpam)₂ (dpam=Ph₂AsCH₂AsPh₂) to afford the dirhenium(III) complexes Re₂(-X)(-PPh₂)HX ₃(-LL)₂. The dppm complexes have also been prepared from the reactions of Re₂(-O₂CCH₃)X ₄(-dppm)₂ with Ph₂PH, and a similar strategy has been used to prepare Re₂(-Cl)(-PPh₂)HCl₃(-dmpm)₂ (dmpm=Me₂PCH₂PMe₂) from Re₂(-O₂CCH₃)Cl₄(dmpm)₂. Phenylphosphine likewise reacts with Re₂ X ₄(-dppm)₂ to give Re₂(-X)(-PHPh)HX ₃(-dppm)₂. An X-ray crystal structure determination on Re₂(-Cl)(-PPh₂)HCl₃(-dppm)₂ confirms its edge-shared bioctahedral structure. This complex crystallizes in the space group (No. 148) witha=21.699(3) Å, =84.50(4)°,V=10084(5) ų, andZ=6. The structure was refined toR=0.049 (R _w 0.069) for 5770 data withI>3.0(I). The Re-Re distance is 2.5918(7) Å. Oxidation of the bromide complex Re₂(-Br)(-PPh₂)HBr₃(-dppm)₂ with NOPF₆ produces the unusual dirhenium(III, II) cation [Re₂(-H)(-Br)[P(O)Ph₂]Br₂(NO)(-dppm)₂]⁺ which has been structurally characterized as its perrhenate salt, [Re₂(-H)(-Br)[P(O)Ph₂]Br₂(NO)(-dppm)₂]ReO₄ · 2CH₂Cl₂. This complex crystallizes in the space group (No. 2) witha=14.187(7) Å,b=16.419(5) Å,c=16.729(5) Å, =98.76(2)°, =110.11(3)°, =104.66(3)°,V=3414(6) ų,Z=2. The structure was refined toR=0.040 (R _w =0.051) for 5736 data withI>3.0(I). The presence of a phosphorus-bound [P(O)Ph₂]^– ligand, a linear nitrosyl and a bridging hydrido ligand has been confirmed. The Re-Re distance is 2.6273(8) Å.     

Reactions of ortho-Phenylenediamine with a Nickel Trimethylacetate Complex

Interaction of ortho-phenylenediamine with the nonanuclear nickel trimethylacetate cluster Ni₉(₄-OH)₃(₃-OH)₃( _n -OOCMe₃)₁₂(HOOCCMe₃)₄(I) in an amine deficiency yields the antiferromagnetic trinuclear complex [Ni₃{-N,N"-(NH₂)₂C₆H₄}₂(HCCOOCMe₃)₃(₃-OH)(-OOCCMe₃)₄]⁺(OOCCMe₃)^–(III) containing bridging diamine ligands. Reaction of excess diamine with Ior IIIleads to the formation of the paramagnetic monomer Ni{²-o-(NH₂)₂C₆H₄}₂(OOCCMe₃)₂(IV), which reacts with atmospheric oxygen to form the known bis(semiquinonediimine) complex Ni[1,2-(NH)₂C₆H₄]₂(V).     

Copper(I) Acetylenide π-Complexes. Synthesis and Structure of Cluster Compound HAmp[Cu9Cl8(C≡CCH2OH)2] (HAmp is 4-Aminopyridinium Cation)

Crystals of the HAmp[Cu₉Cl₈(CCCH₂OH)₂] cluster compound (HAmp is the 4-aminopyridinium cation (NH₂–C₅H₄NH)⁺) were obtained through ac electrochemical synthesis and their structure was determined using X-ray diffraction analysis (DARCh autodiffractometer, /2 scan mode, 3435 independent reflections with F 4(F), R = 0.047). The crystals are triclinic: space group P , a = 12.547(5) Å, b = 12.502(4) Å, c = 8.201(2) Å, = 75.93(2)°, = 82.21(3)°, = 76.05(3)°, V = 1207(2) ų, Z = 2. Two crystallographically independent moieties ^–(CCCH₂OH) were detected in the complex structure. Each moiety acts as a double bridging ,-ligand and binds four or five Cu(I) atoms, thus forming the [Cu₄(CCCH₂OH)] and [Cu₈(CCCH₂OH)₂] clusters. The shortest Cu···Cu distance is equal to 2.337(4) Å.     

Topology of density difference and force analysis

The density difference (r) of a molecule A-B is defined as the difference of the density (r) of the molecule A-B and the density _A(r) + _B(r) put at the position of the atoms A and B. We investigate here the topological features of the density difference and define electron density flow (EDF) as representing the direction and the amount of the electron density flow in the course of the nuclear displacement processes. As such examples, we study H₂ molecule formation reaction and the interaction of two He atoms. By the topological analysis of (r), and by using the Hellmann-Feynman force and its partition into the AD, EC, and EGC forces, the characteristic behaviors of the (r) map are clarified. In particular, the electron cloud preceding and incomplete following are represented by using the concept of the EDF. The natures of the covalent bond are clarified based on the topological properties of the difference density (r) rather than that of the total density (r).On leave from the Department of Chemistry, Hebei Teachers' College, Shijiazhuang, Hebei, 050091, China