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[Ta(C_(10)H_(15))2(C1)(OH)][CF_3SO_3] (I), Mr = 652.94, monoclinic, P2_1/n, a = 9.965(7), b = 18.796 (5), c = 13.269 (3)A, β = 94.02 (3)°, V = 2479-2 (19)A^3, Z = 4, D_x = 1.75 g cm^(-3), λ(Mo Kce) = 0.71073 A, µ = 46 cm^(-1), F(000) = 1288, room temperature, R = 0.107 for 3702 reflections with F_o^2 > 0 [R=0.053 for 2094 reflections with F_o^2 > 3σ(F_o^2)]. [Ta(C_(10)H_(15))_2(OH)_2][CF_3SO_3] (II), M_r = 634.49, triclinic, P1, a = 10⋅052 (2), b = 10⋅111 (2), c = 12⋅739(2) A, ɑ = 71⋅38(2), β = 78⋅21 (1), y = 77⋅40 (2)°, V = 1184⋅7 (4)A^3, Z = 2, D_x = 1⋅78 g cm^(-3), λ(Mo Kɑ) = 0⋅71073 A, µ = 47 cm^(-1) F(000) = 628, room temperature, R = 0⋅032 for 4046 reflections with Fo g > 0 [R = 0⋅026 for 3664 reflections with F_o^2 > 3σ(F_o^2)]. Severe disorder of the triflate anion in (I) led to a less satisfactory structure, but cations in both compounds are well defined, with normal Ta─Cp^* geometry. Ta─C1 2⋅343 (4), Ta─O 1⋅853 (8)A and C1─Ta─O 96⋅4 (3)° in (I); Ta─O 1⋅907(6)A and O─Ta─O 100⋅4(2)° in (II). Tantalum-bound OH groups are hydrogen bonded to triflate O atoms.

Cp*Ir(PMe3)Cl2 (1) reacts with chalcogenide ligand sources such as (NH4)Sx (x ≈ 10), (NEt4)2Se6, and H2Se to yield the half-sandwich complexes Cp*Ir(PMe3)(Sn) [n = 4 (2a), 6 (4a)] and Cp*Ir(PMe3)(Sen) [n = 2 (5b), 4 (2b)]. Desulfurization of 4a by PPh3 leads to Cp*Ir(PMe3)(S5) (3a), while both 4a and 3a react with excess P(nBu)3 to give 2a. The geometries of the cyclo-oligochalcogenide ligands in 4a and 2b have been determined by X-ray crystallography.

Four types of water-soluble iron sandwich compounds, ferrocenes bearing charged side chains (Ia), ferrocenium salts (Ib), (η-arene) 2 Fe 2+ salts (II) and (η-cyclopentadienyl)Fe + salts (III), have been tested in in vitro against experimental tumours, L1210, Walkers and Chinese hamster lung (V.79). Some activity was observed for all the types of complex; though that of only two, Ib and II, was good. Of special interest is that the iron(II) sandwich type II compounds display anti-tumour activity, since previous active complexes have contained type Ib or other known cytotoxic groups that would account for their activity. Examples of complexes of type Ib and II were further tested against improved cell lines L1210, PC6 and CHl. The results show the two types to be similar in their effect and specificity. An attempt is made to rationalise the data.

Zusammenfassung A crystallographical comparison of bis(fulvalene)diiron (BFFefe+) and bis(fulvalene)iron-cobalt (BFFeCo+)mono-hexafluorophosphates reveals strikingly similar lattices.This provides further evidence for a valence averaged system also in the case of the mixed membered [0.0]metallocenophane salt BFFeCo+PF6−. Despite the nearly uniform charge distribution over both metallocene units, the heteronuclear BFFeCo+ molecules are not randomly oriented in the counter-ion enviroment. Lattice layers are slightly displaced in contrast to BFFeFe+ PF6−. The FeFe and the FeCo compound crystallize in the monoclinic space groups C2/m and C2/c, respectively.

The reaction of Cp*HfCl3 with (1,2,3-Me3allyl)MgBr or (1,1,2-Me3allyl)MgBr and excess MgBr2 yields Cp*(1,2,3-Me3allyl)HfBr2 and Cp*(1,1,2-Me3allyl)HfBr2. X-ray crystallography of these compounds shows a bent-metallocene-type geometry, with steric congestion in the asymmetrically methylated compound causing the greatest distortion yet observed of an η3-allyl ligand towards an η1binding mode for an early-transition metal complex. For Cp*(1,2,3-Me3allyl)HfBr2: cell constants a=14.581(7), b=14.725(8), c=8.291(3) A; space group Pcmn; R=0.0425, Rw=0.0397. For Cp*(1,1,2-Me3allyl)HfBr2: cell constants a=9.158(2), b=13.141(4), c=14.575(3) A, β=101.06(2)°; space group P21/n; R=0.0383, Rw=0.0401. A variable temperature 1H NMR study indicates that the allyl ligand in (1,1,2-Me3allyl)HfBr2 undergoes η3-η1 isomerization (ΔG‡(−53 °C)=40.9± 1 kJ/mol).

The preration of di- and tri-phosphollide ions P 3 C 2 R − 2 , P 3 C 2 RR′ − , P 2 C 3 R 2 R′ − , P 2 C 3 RR′ − , P 2 C′ 3 R′ 3 (R = i Pr) and their pentaphospha-ferrocene analogues are described.

A mixture of isomeric (Me 4 C 5 H)(Me 3 C 5 (CH 2 )H)TiMe compounds was obtained by thermally induced methane elimination from (Me 4 C 5 H) 2 TiMe 2 at 130°C, analogous to the formation of (Me 5 C 5 )(Me 4 C 5 (CH 2 ))TiMe. The compound (Me 5 C 5 )(Me 3 C 5 (CH 2 ) 2 Ti was newly prepared in 27% yield by boiling a (Me 5 C 5 ) 2 TiCl 2 LiAlH 4 mixture in toluene, followed by sublimation of the soluble product. By an analogous process, (Me 4 C 5 H)(Me 2 C 5 (CH 2 ) 2 H)Ti was obtained in 10% yield. Neither type of complex was formed by either method from titanocene derivates with fewer methyl groups at cyclopentadienyl ligands.

Time-resolved and steady state optical measurements are reported for the sandwhich complexes consisting of two tetraphenylporphyrin macrocycles held within 3 A by either a Zr IV or Hf IV ion. Compared to monoporphyrins and weakly coupled bisporphyrins, the transition-metal sandwich complexes show new features in both the ground and excited state absorption spectra as well as a broad fluorescence red-shifted to ≈ 1 μm. A model is presented that describes the electronic states responsible for these optical features. The states arise from strong interactions between the porphyrin macrocycles and contain significant charge resonance character.

Thiophene-1,1-dioxide (TDO) is thermally unstable and can be stabilized by coordination to metals in low oxidation states as hitherto shown in the case of some iron carbonyl compounds. We now present examples of cobalt complexes such as CoCp(η4-TDO) (4) and their derivatives: CoCp(η4-2,5-diphenylthiophenedioxide) (5), CoCp(η4-3,4-diphenylthiophenedioxide) (6), CoCp(η4-tetraphenylthiophenedioxide) (7). CoCp(η4-2,5-di-t-butylthiophenedioxide) (8) and CoCp(η4-di-t-butylthiophenedioxide) (9). Also complexes with the η3-ligand 2-hydrothiophenedioxide (TDO-H), containing a cyclic allyl system have been obtained: Co(CO)3(TDO-H) (11). One or two CO groups may be substituted by a variety of organophosphanes and phosphites including the chelating diphosphanes DPPM and DPPE. All compounds have been characterized by 1H and 13C NMR methods. In addition the crystal structures of 4, 7 and Co(CO)(η2-DPPE)(TDO-H) (11i) have been determined.

A reaction between Mn 2 (CO) 10 and 2 equiv of (η 5 -C 5 H 4 PPh 2 )(η 7 -C 7 H 6 PPh 2 )Ti (1) in refluxing toluene results in carbonyl group displacement, metal-metal bond cleavage, and hydrogen abstraction to form HMn(CO) 3 [(η 5 -C 5 H 4 PPh 2 )(η 7 -C 7 H 6 PPh 2 )Ti] (4) in 57% yield. The new chelated heterobimetallic compound 4 has been characterized by its 1 H NMR, 31 P NMR, IR, and mass spectra, as well as by a single-crystal X-ray diffraction study

The complex CpIr(η 4 -C 5 H 6 ) was prepared unexpectedly from the reaction of [(η 2 -C 8 H 14 ) 2 IrCl] 2 and thallium cyclopentadienide

[C 18 H 15 FeO 2 ] [PF 6 ] cristallise dans P2 1 /c avec a= 7,976, b=8,959, c=24,936 A, β=99,00 o , Z=4, T=163 K; affinement jusqu'a R=0,044. L'angle diedre entre les cycles arene du coordinat dioxine est de 173,8 o ; les longueurs des liaisons par rapport au cycle coordine sont notablement plus courtes que celles du cycle non coordine. L'inclusion d'atomes electronegatifs dans les cycles arene des trianthrenes et la complexation de FeCp par les cycles arene provoquent l'aplatissement de l'angle diedre

The introduction of an alkylcarbonyl side chain into the aromatic ring of some chloro-substituted benzenes has been achieved under mild conditions by the Yanovsky-type reaction of (η6chloroarene)(η5-cyclopentadienyl) cationic complexes of iron or ruthenium with silyl enol ethers. An ester side chain has been introduced similarly using ethyl trimethylsilylacetate. The resulting (η5-chlorocyclohexadienyl)(η5-cyclopentadienyl) adducts derived from the ruthenium salts are more stable than their iron analogues. Treatment of the neutral ruthenium adducts with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone gives moderate yields of the [η6-(substituted chloroarene)(η5-Cp)]Ru+PF−6 salt, together with the decomplexed substituted chloroarene.

The reactions of 4-methylpyridine (1), 3-methylpyridine (2), 2-methylpyridine (3), 3,5-dimethylpyridine (4), 2,4-dimethylpyridine (5), 2,4,6-trimethylpyridine (6), N-methylpyrrole (7), quinoline (8), isoquinoline (9), 2-methylquinoline (10), 1,2,3,4-tetrahydroquinoline (11), N-methylindole (12), acridine (13), phenanthridine (14), 5,6-benzoquinoline (15), and 7,8-benzoquinoline (16) with (η 5 -pentamethylcyclopentadienyl) rhodium dicationic complexes [Cp*Rh(CH 3 CN) 3 ](X 2 ) or [Cp*Rh((CH 3 ) 2 CO) 3 ](X 2 ) (X=PF 6 or BF 4 ) were studied to ascertain how structure influenced the reactivity of ligands, 1-16, to provide nitrogen (N) versus π-bonded Cp*Rh 2+ complexes

Naphthaleneytterbium, C10H8Yb(THF)3, reacts with Cp2Cr, Cp2Co, Cp2Ni, and Cp2V in THF to give Cp2Yb. In the case of the reaction of C10H8Yb(THF)3 with Cp2V, vanadium-containing intermediates could be isolated. One of them, CpVC10H8VCp, has been characterized by X-ray diffraction. The crystals are monoclinic, space group P21/n, with a 907.0(5), b 798.8(3), c 1080.8(5) pm, β 105.21(4)°; Z = 2. The structure was refined to R = 0.0288 for 1131 observed reflections (Fo > 4σ(Fo)).

We have performed realistic tight-binding band calculations for a series of (X${)}_{3}$/(Cr${)}_{\mathit{m}}$/(X${)}_{3}$ sandwiches with bcc [001] interfaces, for X=Fe, Co, and Ni and m=3, 4, and 5. The moment distributions on the X and Cr layers have been determined self-consistently. In all the cases investigated, we have obtained locally stable, multiple solutions in which the ferromagnetic and antiferromagnetic couplings are realized between magnetic moments on successive X layers across intervening Cr layers. The similarities and differences in the magnetic properties among the three sandwiches are discussed. We also discuss implications of the results of our calculations on the magnetoresistance data recently obtained for Fe/Cr and Co/Cr multilayers.

Heterocycles as Ligands, XI. – Octamethyl-1,1′-diazaferrocene as a Bifunctional Nitrogen Base (C4Me4N)2 Fe·2 HNC4Me4 (3) reacts with Bronstedt and Lewis acids to give the adducts [(C4Me4N·E)2Fe]n+ [4 – 6, 11 – 13; n=2, EH, CH3, CH3C(O); n=O, EBH3, BF3, Fe(CO)4]. The stepwise substitution of the tetramethylpyrrole molecules in 3 leads to the complexes [(C4Me4N·E)(C4Me4N·E')Fe]n+ [16, 17, 19; n – O, EC4Me4NH, E'=Fe(CO)4; n=1, EBH3, E'=H; n=2, EH, E'=CH3]. Similarly, the complexes [{(C4Me4N)C(O)CH2CH2C(O)(NC4me4}Fe]Cl2 (9) and [Ag2{μMe4N)2Fe}2Fe}2](BF4)2·2 MeOH (15) are obtained. Reaction of [(C4Me4NH)2Fe](BF4)2 (4) with nBuLi gives the protonated diazaferrocene [(C4Me4NH)(C4Me4N)Fe]BF4 (18) from which the dimeric iron diamide {(C4Me4N)2Fe}2 (20) is obtained on further deprotonation.

(η 5 -Cyclopentadienyl)(η 7 -cyclooctatrienyl) vanadium (1) can be obtained by a one-pot reaction in THF by starting from VCl 2 , NaCp (Cp=cyclopentadienyl), and K 2 Cot (Cot=cyclooctatetraene) as simple educts and with subsequent hydrolysis. The monodeuterated derivative 1-d is obtained on hydrolysis of the reaction mixture with D 2 O

Infrared spectra (4000-50 cm −1 of triple-decker sandwich cation [(CpNi)(μ  Cp)(NiCp)] + (Cp  η-C 5 H 5 ) in solid state and in solutions have been studied. The assignment of terminal and bridged Cp-ring vibrations was proposed by comparison with the spectra of nickelocene. The frequencies of the terminal and the bridged Cp-ring vibrations differ to within 10–25 cm −1 . According to the spectral data the terminal Cp-rings are bonded to the metal atoms stronger than the bridged one. The assignment of skeletal vibrations of (Cp 3 Ni 2 ) + cation is proposed.

(Butadiene)(cyclopentadienyl)niobium Complexes The known bis(butadiene)(cyclopentadienyl)niobium complex (C5H4R)Nb(C4H6)2 (1, RH) exists in solution as a 1 : 1 mixture of a bis(cis-butadiene) isomer 1a and a (cis-butadiene)(trans-butadiene) isomer 1b. In solution the barrier to isomerisation is 80 ± 2 kJ/mol. New derivatives 2 (RMe) and 3 (RSiMe3) of 1 are described. One of the butadiene ligands in 1 – 3 is readily substituted with CO, CNtBu, P(OMe)3, and PMe3. CpNb(PMe3)2(C4H6) (7) reacts with disubstituted acetylenes to form acetylene complexes CpNb(PMe3)(C4H6)(RCCR') (8: R, R'=Ph, 9: RMe, R'=Ph, and 10: RPh, R'=SiMe3), The structure of 9 resembles that of bent metallocene derivatives with the acetylene acting as a 2-e ligand.

Treatment of (EBTHI)MCl 2 [M=Zr, 1; M=Hf, 2; EBTHI=ethylene-1,2-bis(η 5 -4,5,6,7-tetrahydro-1-indenyl)] with 2 equiv of NaEt 3 BH in C 6 H 6 produces the hydride dimers [(EBTHI)MH(μ-H)] 2 (M=Zr, 3; M=Hf, 4). The dimethylhafnium complex (EBTHI)HfMe 2 (5) is formed when 2 is treated with MeLi in C 6 H 6 . Complexes 3 and 4 can be protonated with the weak acid [PhMe 2 NH][Co(C 2 B 9 H 11 ) 2 ] to give monomeric cationic hybrides [(EBTHI)M(H)(NPhMe 2 )][Co(C 2 B 9 H 11 ) 2 ] (M=Zr, 6; M=Hf, 7), in which the N,N-dimethylaniline ligand is very weakly coordinated to the metal

Benzyltetramethylcyclopentadiene (Me 4 C 5 CH 2 Ph) was prepared in high yield from commercial reagents and deprotonated with butyllithium to give the red title anion, which was converted to the orange sandwich complex (Et 2 C 2 B 4 H 4 )Co(Me 4 C 5 CH 2 Ph) (1) via reaction with CoCl 2 and Na + Et 2 C 2 B 4 H 5 − in THF. Decapitation of 1 with wet TMEDA gave yellow (Et 2 C 2 B 3 H 5 )Co(Me 4 C 5 CH 2 Ph), which in turn was bridge-deprotonated and reacted with CoCl 2 and the title anion to give a burgundy-colored triple-decker complex, (Et 2 C 2 B 3 H 3 )Co 2 (Me 4 C 5 CH 2 Ph) 2

Thin high resistance films of superconductors have a reduced Tc. This reduction has been recently explained with the enhanced Coulomb interaction in disordered two dimensional metals. We investigate the superconductivity in a sandwich of two thin superconducting Bi films separated by an insulating Sb layer. The results do not confirm the “Coulomb interpretation”.

The nitrogen heterocyclic ligands pyridine, 2-methylpyridine, 2,4-dimethylpyridine, 2,4,6-trimethylpyridine, quinoline, isoquinoline, 2-methylquinoline, and 1,2,3,4-tetrahydroquinoline were reacted with (η 5 -cyclopentadienyl)ruthenium cation, [CpRu(CH 3 CN) 3 ](PF 6 ), to ascertain the mode of bonding as a function of structure, i.e., nitrogen (η 1 (N)) versus π (η 6 ) bonding

Spin-lattice relaxation times (T1) are reported for a series of ferrocene derivatives and related sandwich complexes. These values have been used to investigate the relative importance of overall molecular reorientation (tumbling, correlation time τc) and internal rotational motions (τm). A series of sterically crowded ferrocenes were examined and τ m τ c ratios obtained. For triphenylmethylferrocene derivatives all internal rotations appear “locked” and the molecules simply tumble as approximate spheres. For cationic sandwich complexes the formal charge has little effect on T1. Ion pairing in CpM derivatives is also explored using relaxation data.

The interfacial behavior between bilayers of aluminum and ruthernium dioxide deposited by (r.f.) magnetron sputtering has been studied after annealing at temperatures in the range 450°C–550°C for durations up to several hours by backscattering spectrometry, cross-sectional transmission electron microscopy and electrical four-point probe measurement of specially designed structures. An interfacial aluminum-oxygen compound layer is shown to grow with a concurrent reduction of a thin layer of RuO2. This result is independent of the various deposition conditions investigated. Cross-sectional transmission electron microscopy shows this interfacial layer to be polycrystalline and very non-uniform. Specially designed structures of the type 〈Si〉/SiO2/Al/RuO2/Al were annealed and measured with four-point probe setups having different probe spacings. Applying a transmission line type-model for four-point probe measurement of multilayered structures, the specific contact resistance between Al and RuO2 was derived and shown to decrease with annealing duration at 500°C. This evolution of the specific contact resistance indicates that the interfacial reaction does not lead to an insulating interface as could have been expected if the interfacial growth were pure and dense Al2O3.

The vibrational properties of 1 monolayer of Cu adsorbed on O/W(110), Cu1/O/W(110), O/Cu1/W(110) and Cu1−1.5/CO/W(110) were studied at 90 K and on heating to see if the existence of sandwich structures and the electric shielding by single metal layers suggested by previous work [N. Shamir, J.C. Lin and R. Gomer, J. Chem. Phys. 90 (1989) 5135] could be confirmed. It was found that a monolayer of Cu screens the OW dipole moment effectively while 1.5 Cu monolayers were required for CO on W, probably because in that case a continuous Cu layer is not formed. It was also found that heating Cu1/O/W(110) and O/CU1W(110) layers gave results which support previous findings on OCu segregation [J.S. Lin, N. Shamir and R. Gomer, Surf. Sci. 206 (1988) 206].

Protonation of Ru(η 4 -C 8 H 12 ) (η 6 -C 8 H 10 ) by HBF 4 •Et 2 O at −80 o C initially produces [RuH(η 4 -C 8 H 12 )(η 6 -C 8 H 10 )] BF 4 (1). Complex 1 isomerizes in solution to [RuH(η 5 -C 8 H 11 ) 2 ] BF 4 (2). Complex 2 reacts with acetone to give an equilibrium mixture of 2 and [Ru(η 5 -C 8 H 11 )(η 4 -C 8 H 12 )-(acetone)] BF 4 (3). The reaction of 1 with S (S=MeCN, H 2 O) produces [Ru(η 5 -C 8 H 11 )S 3 ] BF 4 (5 and 4, respectively), while with C 5 Me 5 H the complex [Ru(η 5 -C 5 Me 5 )(C 8 H 12 )] BF 4 is formed. 1 also reacts with PMePh 2 to yield [Ru(η 5 -C 8 H 11 )(PMePh 2 ) 3 ] BF 4 (6) and with C 6 Me 6 to yield [Ru(η 5 -C 8 H 11 )(η 6 -C 6 Me 6 )] BF 4 (10). Complex 1 or its derivatives are catalysts for 1-alkene isomerization, ethylene dimerization, and ring-opening polymerization of norbornene

A calculation of spin-wave propagation through a nearly nonmagnetic film sandwiched between two magnetic films is given as a function of the thickness of the nonmagnetic film and of a parameter that describes the decay of the exchange through this film and can be related to structural features such as interface roughness or spin-polarization penetration depth. The comparison with experiment enables us to determine this exchange decay parameter for a series of experiments in Permalloy-copper-Permalloy sandwiches prepared in an UHV system.

The synthesis of the (η 5 -C 5 Ph 5 ) 2 Mo 2 (CO) 6 complex is described. In solution, the dimer is in equilibrium with 2 17-electron (η 5 -C 5 Ph 5 ) Mo(CO) 3 monomers. The equilibrium constant for the dimer-monomer equilibrium, as determined by electronic absorption spectroscopy

Treatment of a suspension of AgBF4 in absolute methanol with a solution of η5-C5H5Ru(PPh3)3Cl (1) and an arene gives [(η5- or η6-arene)Ru(η5-C5H5]BF4; where the η5 or η6-arenes are thiophene (2), nitrobenzene (3), N,N-dimethyl-4-nitroaniline (4), 2-methyl-4-nitroaniline (5) and N-(4-nitrophenyl)(l)-prolinol (6). The relative efficiency of second-harmonic generation (1064 nm→532 nm) for compounds (1–6) is 0.7 to 1.0 × urea.

From the reaction of the 4,8-ethano-2,4,6,8-tetrahydro-s-indacene-2,6-diyl dianion (L) and cyclopentadienyl (Cp) anion with iron(II) chloride the bridged ferrocenes syn,syn-CpFeLFeCp (4), syn,anti-CpFeLFeCp (5), and all-syn-CpFeLFeLFeCp (6) were obtained. The structures of 4-6, including syn, anti isomerism, were deduced from their 1 H and 13 C NMR and mass spectra. X-ray crystal analyses were carried out for 4 and 5

Ferrocene forms a series of unusual charge-transfer crystals with the isoelectronic bis(arene)iron(II) dication, in which X-ray crystallography establishes the alternate (heterosoric) stacking of sandwich structures comprising the donor-acceptor pairs. In acetonitrile, the 1:1 complex (Cp{sub 2}Fe, Ar{sub 2}Fe{sup 2+}) shows a broad absorption band centered at {lambda}{sub max} {approximately} 630 nm. Bis(arene)iron(II) acceptors also form highly colored crystals with various arene donors, in which the charge-transfer absorption (hv{sub CT}) derives from the same heterosoric stacking of donor-acceptor pairs-despite the structurally divergent nature of the arene (planar) and ferrocene (sandwich) donors. These absorptions undergo a predictable red-shift with increasing acceptor strength in the order (BZ){sub 2}Fe{sup 2+} > (MES){sub 2}Fe{sup 2+} > (DUR){sub 2}Fe{sup 2+} > (HMB){sub 2}Fe{sup 2+}, as judged by the reduction potentials E {sub red} of the benzene, mesitylene, durene, and hexamethylbenzene derivatives, respectively.

An X-ray crystal study of the nickel oxide-siloxanolate complex {[PhSiO] 6 (μ 4 -O) 2 (μ 3 -O) 4 [Ni 8 (μ 3 O) 2 ] (μ 3 -O) 4 (μ 4 -O) 2 [PhSiO] 6 }·14n-BuOH·10H 2 O·2MeCO (I or Ia without noncoordinating solvate molecules) having a cage structure has been carried out. The complex studied was prepared by the interaction of NiCl 2 with the product of the reaction of phenylsilsesquioxane (PhSiO 1.5 ) n with NaOH. The polynuclear cage-like centrosymmetric molecule Ia has a sandwich-type structure. The inner two-dimensional nickel oxide fragment Ni 8 o 2 (μ-O) 12 2 = Ni 8 O 8 is structurally identical to a fragment of the NiO crystal layer which is one Ni atom thick and parallel to the (111) plane. All Ni atoms have oxygen atoms in an octahedral coordination (oxide, silanolate, molecules of water, butanol and acetone). The O atoms of the nickel oxide layer have both trigonal pyramidal (μ 3 -O) and distorted tetrahedral (μ 4 -O) coordination. The nickel oxide layer is bonded by NiOSi bridges through silanolate O atoms with two outer 12-membered hexasiloxane (SiO) 6 cycles (sandwich “caps”) with an almost ideal crown conformation. Some of the butanol and H 2 O crystallosolvate molecules do not coordinate the Ni atoms being included in the cavities between Ia molecules. The NiO bond lenghts are 2.006–2.159 A, while the average SiO(Si) and SiO(Ni) bond lengths are 1.637 and 1.618 A, respectively.

The thermal decomposition of Ru(η4-C8H12)(η6-C8H10) has been studied both isothermically and using temperature-programmed technqieus (TPDE). Under a flow of H2, the TPDE gave spectra which showed two peaks, which indicates the formation of an intermediate species (which has not been characterized). The cyclooctadiene and cyclooctatriene ligands produce a complex mixture of saturated cluster, obtained after the decomposition of Ru(η4-C8H12)(η6-C8H10) under a flow of H2, towards the hydrogenation of CO and olefins, have been studied. Reactions with CO + H2 led mainly to CH4. The hydrogenation of cyclooctadiene and cyclooctatriene was complete at room temperature, and the distribution of the products of the reactions is similar to those obtained during the TPDE of Ru(η4-C8H12)(η6-C8H10). The TPDE of Ru(η4-C8H12)(η6-C8H10), under a flow of H2, can be seen as an interesting model of the Ru metal reactivity towards the hydrogenation of these olefins.

Direct observations of the counter-electrode surface of electroformed Au-I-Cu sandwich structures (where I is reactively evaporated AlO x or GeO x ) were carried out using scanning electron microscopy. Electron microprobe analyses of surface defects in electroformed samples, after etching the copper counter-electrode, tended to confirm the presence of copper. Surface defects are identified as the terminations of filament bundles, which supports the filamentary model of conduction.