Bei der Reduktion von Eisen(l1)-Verbindungen mit Alkalimetallen oder iiber eine Alkylierung mit Grignard-Reagenzien in Gegenwart von l ,CDilza-l,3-dienen (DAD) entstehen die paramagnetischen, braunen, vierfach koordinierten Eisen (0) Eisen(N-chelate) haben zusatzlich zu ihrer bekannten biochemischen Funktion dadurch Bedeutung gewonnen, daB sie in homogenkatalytischen Reaktionen fur die Umsetzung einfacher Kohlenwasserstoffe als aktive Zentren auftreten. Schon vor langerer Zeit wurde gcfunden, daB Bis(bipyridy1)eisen und venvandte Verbindungen Butadien bei hoherer Temperatur zu dimerisieren vermogen '). Bei der reduktiven Aktivierung von Eisenverbindungen mit Aluminiumalkylen wurden auch bereits Schiff-Basen als Liganden verwendet'), ohne daB deren Reaktionen mit Hauptgruppenmetallorganylen bekannt waren'). 1,4-Diaza-1,3-diene (DAD = RN = C R -C R = NR) haben sich fur katalytische Reaktionen als besonders vielseitige Steuerliganden erwiesen und gerade auch am Eisen zu sehr selektiven Reaktionen gefiihrt 4,5). DAD vermogen Metalle gut in niedrigen Oxidationsstufen zu stabilisieren6', allerdings ist eine strenge Zuordnung einer Oxidationsstufe zum Metal1 kaum moglich (non-innocent ligands')). Die Koordinationschemie der DAD an Eisencarbonyl-Fragmenten erwies sich als weit vielfaltiger, als wir das bei der ersten Synthese von (DAD)Fe(COh angenommen hattens-"). Auch Verknupfungsreaktionen mit Alkinen in diesem System sind beschrieben ll). Wir haben den Komplextyp (DAD)2Fe im Hinblick auf seine Elektronenstruktur, seinen Oxidationszustand und seine Reaktionen rnit n-Akzeptorliganden und einigen Elektrophilen untersucht. Reactions of Bis(diazadiene)iron(O) ComplexesReduction of iron(l1) compounds with alkali metal or via an alkylation with Grignard reagents in the presence of l .4-diaza-1,3-dienes (DAD) yields the brown, paramagnetic, tetracoordinatc iron(0) complexes Fe(DADh 2. Depending on the bulkiness of the DAD substituents, carbon monoxide does not add or adds more or less readily and reversibly to give deep green diamagnetic (DAD)2Fe(CO) 6, or in an irreversible manner to give red (DAD)-Fe(COh 8. A corresponding colour change occurs during the addition of isocyanide to give 7 and 10, rcspcctively. Further addition reactions of 2 are observed with dicyanogen, nitrosyl chloride, or a diazoalkane. Two molecules of a dialkyl acetylenedicarboxylate are added to sterically not too demanding complexes 2 and with concomitant C-C bond formation an airstable, deeply blue coloured ferracyclopentadiene 9 is formed. A single crystal X-ray investigation of monoclinic 9b was performed. The molecules of symmetry C2 contain two DAD-chelates and a tetrakis(alkoxycarbonyl)-l,3-butadiene-l,Cdiyl chelate at the octahedral iron(l1) center.
The scope of electroless copper plating technology is evolving to applications with smaller structures and smoother substrates, where adhesion of the copper film can be hard to achieve. The extent to which different factors, such as film stress and hydrogen evolution, contribute to delamination and blister formation on smooth organic substrates is a topic of active discussion. Stress and strain evolution is reported here for a nickel-and formaldehyde-free formulation for a range of plating bath temperatures. X-ray diffraction, with the sin 2 ψ method, was used to monitor the strain within the copper crystallites during and after their growth. Substrate bending measurements were used to detect the average stress of the film. This technique indicates a 60 nm wide zone of tensile stress at the interface between substrate and film. During and immediately following deposition, the average substrate stress is more compressive than implied by the strain of the Cu crystallites. After deposition, the additional compressive stress seen by substrate bending relaxes until it matches the Cu crystallite strain. Furthermore, the thermal substrate contraction effect upon termination of plating is considered, since it may influence the film adhesion.Electroless copper films, widely used in the printed circuit board industry, are currently being optimized for providing interconnects for future generations in integrated circuit (IC) substrates. For such applications, the industry is moving toward specifying limits for stress in electroless copper deposits. Nickel is frequently added to electroless copper baths because it controls the film stress 1 and because it reduces hydrogen evolution during deposition. 2,3 However, co-deposited nickel reduces the conductivity of the copper deposits, which may be a problem in high-end applications that require confined current paths during the subsequent galvanic copper plating. Further, nickel as an additive and formaldehyde as the reducing agent are incompatible with the desire to employ green chemistry processes wherever possible. In order to produce highly reliable films within these constraints, one has to monitor the factors that are known to limit film adhesion, the film stress 4 and co-deposited hydrogen. 2 Hydrogen, co-deposited at typical pressures of 70 MPa in grain boundaries, 5 reduces the film ductility and adhesion. 2,6-8Here we present X-ray diffraction and substrate curvature measurements that are sensitive to the strain of the copper crystallites and the average stress of the copper film, respectively. These measurements were carried out during and after film deposition from a bath formaldehyde-free and nickel-free at different temperatures. For chemical vapor deposition, physical vapor deposition, and sputtering the film stress found by these two methods usually agrees. 9-11 In the present case, significant differences can be observed in the more complex electroless deposition process. ExperimentalThe Cu films were produced from an electroless nickel-free bath containing 3 g/...
Die aus Glyoxalhydrat und primaren Alkylaminen leicht zuganglichen Diazadiene R -N = CH -CH = N -R (1: R = tert-Butyl, 2: R = Isopropyl) reagieren mit trockenem Chlorwasserstoff in wasserfreien Losungsmitteln unter Eliminierung von Alkylammoniumchlorid zu N,N'-diakylierten Azomethinderivaten der 2-Formylimidazoliumchloride. Die tert-Butylimin-Verbindung 3, deren Struktur durch eine Einkristallrontgenanalyse belegt ist, laDt sich im Sauren zum Aldehyd 4 hydrolysieren. Das 3-analoge Isopropylimin 5 reagiert unter Transaminierung gleich weiter zum 2-Aminomethylderivat des Imidazoliumsystems und wird als Hydrochlorid 6 erhalten. Am Beispiel von 6 wird ein verbessertes Routine-APT-Verfahren fiir die "C-NMR-Spektroskopie vorgestellt, welches bei konstantem Zeitaufwand die Sicherheit der Zuordnung erhoht, insbesondere falls ungewohnliche 'JcH-Kopplungskonstanten auftreten kiinnten. Synthesis of ZFunctionalized N,~-Dialkylimidazolium Salts from Glyoxal and Alkylamines Diazadienes R-N=CH-CH=N-R(1: R = tert-butyl, 2 R = isopropyl), which are easily prepared from aqueous glyoxal and primary alkylamines, react with dry hydrogen chloride in non-aqueous solvents to form N,N'-dialkyl-substituted azomethine derivatives of 2-formylimidazolium chlorides, concomitant with the formation of alkylammonium chlorides. The tert-butylimine compound 3, the structure of which was established by singlecrystal X-ray diffraction, is hydrolyzed to give the aldehyde 4. The intermediate isopropylimine 5, an analogue to 3, is converted directly under transamination into the 2-aminomethyl derivative of the imidazolium system, and is isolated as its hydrochloride 6. With 6 as an example, an improved routine APT method in 13C NMR spectroscopy is presented, which makes assignments more reliable in cases where unusual 'JCH couplings might occur. Reaktionen von 1,4-Kondensationsprodukten von Glyoxal und primaren Aminen, mit zahlreichen Elektrophilen wurden bisher von uns intensiv untersucht. Dabei lag der Schwerpunkt unseres Interesses bei Reaktionen mit ij'bergangsmetallen, auch in niedrigen Oxidationsstufen, z. B. im Hinblick auf die Steuerung katalytischer Reaktionen').Auch die Reaktion von DAD mit Nucleophilen wie RLi oder RMgX und die losungsmittelabhangige Steuerung von N-bzw. C-Addition wurde von uns ebenso untersucht wie die Reaktionen der DAD-Radikalanionen als Nucleophile gegeniiber Alkyl-und Silylhalogeniden').
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