which is attributable to antisymmetric angle deformations. The band is significantly split, an observation contrary to that observed for the noncoordinated example; the splitting is less than that observed for unidentate or bidentate coordination. Thus, unfortunately, the infrared data do not rule out bidentate perchlorate bonding, but the nature of the spectral features does seem to discount the possibility. The crystal structure of this complex is currently under investigation in our laboratories.Note Added in Proof. Complete structural details for [Cu(bipy)OH]2(C104)2 are now available [M. Toofan, A. Boushehri, and M. Haque, J. Chem. SOC., Dalton Trans., 217 (1976)l. The refined structural results reveal that the Cu-0-Cu angle, 4, is 96.94', and that the perchlorate ion is coordinated in the bidentate manner described for cu-[Cu-(dmaep)OH]2(C104)2. The new value for 4 gives a 2 J prediction of +45 cm-'. The more positive experimental value of +93 cm-I deviates from the linear relationship in the same manner that has been noted for cy-[Cu(dmaep)OH]2(C104)2, that is, 2 J was predicted to be -50 cm-' while the experimental value was found to be -4.8 cm-'. Acknowledgment.We wish to thank Professor Stephen F. Pavkovic for making his structural data for [Cu(tmen)-O H ] 2(C104)2 available to us prior to publication and for permission to use those data in this paper.The various factors affecting the formation and stability of neutral, chelated four-coordinate organoaluminum-nitrogen compounds have been investigated. A variety of new compounds have been prepared and fully characterized. Cryoscopic molecular weight data suggest the predominant species to be the chelated monomer for the compounds (CH3)2AI(C2and (CH3)2AISC2H4N(CH3)2. At lowered temperatures, N M R studies and additional molecular weight data suggest that an equilibrium exists between the monomeric chelate and a dimer. Other compounds such as ( C H~) Z A I ( C H~) N C~H~N ( C H~)~, ( C H~) Z A I ( C H~) N C~H~N ( C H~)~, and (C2Hj)2AI(CH3)NC3H6N(CH3)2 show a significant concentration of the dimeric species at room temperature. The dimer molecule can exist in cis and trans conformations relative to the nitrogen of the four-membered ring. In all cases observed, the cis isomer is preferred. An unusual observation is that [(CH3)2AI-N(CH3)C2H4N(CH3)2]2 is present as only the cis isomer at low temperature. Many factors are shown to affect the position of the monomer-dimer equilibrium. These include steric effects of groups bound to aluminum, steric effects of groups bound to potentially bridging and terminal nitrogens of the ligand, ligand base strength, and chelate ring size. There is also evidence that the mechanism of formation may affect chelation and association. H~) N C Z H~N ( C Z H~) Z .An electrochemical study of the Cun+/[R2dtc]-system in aprotic solvents defines the electron transfer relationships between bis-chelated complexes of copper in the three oxidation states I, 11, and 111. Cu(R2dtc)z undergoes single one-electron oxidation and reduction ste...

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Previous work has shown that photomask blank flatness as well as photomask patterning and pelliclization all play an important role in finished photomask flatness 1,2 . Additional studies have shown that pellicle mounting techniques, pellicle adhesives, frame flatness and shape and pellicle mounting tools 3-6 play a role as well. It has become clear that frame flexibility, coupled with frame mounting surface flatness and shape are the principal factors influencing the pellicle effect on the mask distortion. Pellicle suppliers have begun to evaluate various polymers as potential replacements for the standard aluminum frame in current use. The elasticity of the frame adhesive has also been adjusted to evaluate its effect on the pellicle influence on mask flatness. This paper describes some joint evaluations between IBM, Toppan and ShinEtsu, performed to determine the effect of pellicle frame composition,, mount surface flatness, adhesive elasticity and adhesive surface flatness on the distortion of photolithography masks. It demonstrates that polymer pellicle frames with more flexible adhesive improve finished mask flatness approximately the same amount as reducing the total frame standoff height of aluminum frames with conventional adhesive.

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