Supporting Information (SI) A Redox-Fluorescent Molecular Switch Based on a Heterobimetallic Ir(III) Complex with a Ferrocenyl Azaheterocycle as Ancillary Ligand. Fabiola Zapata, Antonio Caballero, Arturo Espinosa, Alberto Tárraga* and Pedro Molina* Departamento de Química Orgánica. Facultad de Química. Universidad de Murcia. Campus de Espinardo, E-30100 Murcia, Spain. E-mail: pmolina@um.es atarraga@um.es Table of contents General comments... S3 Computational details... S3 Figure SI 1. Relative energies for all possible stereoisomers of model complex 3... S3 Synthesis and relevant spectral and characterization data... S4 Figure SI 2. 1 H- and 13 C-MR spectra of complex 2.... S5 Figure SI 3. Cyclic voltammograms of 2 at different scan rates.... S6 Figure SI 4. Anodic (left) and cathodic (right) current intensities versus the S1
square root of the scan rates.... S6 Figure SI 5. Evolution of the LSW during the course of the monooxidation of 2.... S7 Figure SI 6. Evolution of UV-Vis-IR spectra during the course of the oxidation of compound 2.... S7 Figure SI 7. Calculated HOMO, HOMO-2 and LUMO surfaces for complex 2.... S8 Figure SI 8. Calculated MO diagrams for 2 and 2 +.... S9 Calculated structures. Cartesian coordinates and energies of 2, 2 + and 3.... S10 References.... S15 S2
General comments.- Melting points were determined on a hot-plate melting point apparatus and are uncorrected. 1 H- and 13 C-MR spectra were recorded at 300 MHz. Chemical shifts refer to signals of tetramethylsilane in the case of 1 H and 13 C spectra. Quantum yield values were measured with respect to anthracene as standard (Φ = 0.27±0.03), 1 using the equation Φ x /Φ s = (S x /S s ) [(1-10 -As )/(1-10 -Ax )], 2 where x and s indicate the unknown and standard solution, respectively, Φ is the quantum yield, S is the area under the emission curve and A is the absorbance at the excitation wavelength (λ exc = 250 nm) Computational details.- Calculated geometries for complex 2, its oxidized derivative 2 +, as well as the 2- unsubstituted derivative were fully optimized in the gas-phase with tight convergence criteria and using ultrafine grids for integrals (pruned grids consisting on 99 radial shells and 590 angular points per shell around every nuclear position) at the DFT level with the Gaussian 03 package. 1 The B3LYP 2 functional and the 6-31G* basis set, augmented with diffuse functions at atoms (denoted as aug6-31g*), were used for all atoms - except Ir, for which SDD-ecp was employed. All PF 6 counteranions were systematically omitted in all calculated cationic structures. Reported energies do not include the ZPE (zero-point energy) correction. In order to demonstrate the expected preference exhibited by the ppy C donor atoms to occupy trans-positions with respect to the phenanthroline donor atoms, a preliminary study was performed on a 2- unsubstituted model complex 3 (Figure SI 1), in the potential energy surface at either the working level of theory (method A) or the higher B3LYP/aug6-311G**/SDDecp level (method B). + + + H Ir H Ir H Ir 3 2eq/2ax 3 3eq/1ax 3 4eq Method A [0.00] [1.22] [10.96] Method B [0.00] [1.20] [11.28] S3
Figure SI 1. Possible stereoisomers of model complex 3. In brackets their relative energies (in Kcal/mol) using method A (black) or B (gray). Synthesis and characterization data of complex 2.- A solution of [Ir(ppy) 2 Cl] 2 (160 mg) and 2-ferrocenyl-imidazo[4,5-f]-1,10- phenanthroline 1 (120,6 mg) in CH 2 Cl 2 -MeOH (30 ml, 2:1, v/v) was heated to reflux. After 4 h, the yellow solution was cooled to room temperature, and then a 10-fold excess of potassium hexafluorophosphate was added. The suspension was stirred for 2 h and then was filtered to remove insoluble inorganic salts. The solution was evaporated to dryness under reduced pressure. The solid residue was recrystallized from CH 2 Cl 2 - ether to give 2 (215 mg) in 68 % yield. S4
Ir H + Fe PF 6-1 H MR 2 13 C MR Figure SI 2. 1 H- and 13 C-MR spectra of complex 2 (in DMSO-d 6 ). S5
Figure SI 3. Cyclic voltammograms of 2 (1 mm) in CH 2 Cl 2 with [(n-bu) 4 ]PF 6 0.1 M as supporting electrolyte, Ag/AgCl, as the reference electrode. Different scanning rates were used to check the reversibility of the system. Figure SI 4. Plots showing the anodic (left) and cathodic (right) current intensities versus the square root of the scan rates, obtained from the CV of 2 (1 mm) in CH 2 Cl 2 with [(n-bu) 4 ]PF 6 0.1 M as supporting electrolyte. S6
Figure SI 5. Evolution of the LSW during the course of the monooxidation of 2 (1mM in CH 2 Cl 2 ) at + 0.8 V with [(n-bu) 4 ]PF 6 0.1 M as supporting electrolyte, obtained using a rotating disk electrode at 100 mv/s and 1000 rpm. Figure SI 6. Evolution of UV-Vis-IR spectra during the course of the oxidation of compound 2 (1 mm) in CH 2 Cl 2 with [(n-bu) 4]PF 6 (0.15 M) as supporting electrolyte when 1 electron is removed. Arrows indicate absorptions that increase or decrease during the experiment. S7
S8
Figure SI 7. Calculated (a) HOMO, (b) HOMO-2 and (c) LUMO (0.04 isovalue) surfaces for complex 2. S9
Electronic Supplementary Information for Dalton Transactions Figure SI 8. Calculated MO diagrams for 2 (black and gray) and 2 + (blue). Energies, in ev, are quoted relative to the highest Ir-based HOMO (HOMO-2 for 2, or degenerated α-homo or β-homo for 2 +). S10
Calculated structures.- Cartesian coordinates (Å) and energies (au) for 2, 2 + and 3.- Compound 2 (singlet): E = -3430.56268771 au C 0.00000000 0.00000000 0.00000000 C 1.44136260 0.00000000 0.00000000 C 1.87837068 1.35526835 0.00000000 C 0.72453427 2.19624906-0.00476096 C -0.43307040 1.37112297-0.00883506 H 2.09211812-0.86587567-0.00567827 H 2.90809988 1.68632729-0.01158207 H 0.72911931 3.27785779-0.02086664 H -1.46413236 1.69506628-0.01173900 Fe 0.71625106 0.95895466-1.65693889 C 0.07303586-0.05085149-3.33353245 C -0.45735710 1.27431463-3.31646005 C 0.64109147 2.18630139-3.30610016 C 1.84835032 1.42536690-3.31270215 C 1.49744884 0.04147506-3.32986046 H -0.50718055-0.96471452-3.33182142 H -1.50602348 1.53979934-3.30260315 H 0.57107421 3.26583304-3.28236828 H 2.85304259 1.82681765-3.29751367 H 2.19101657-0.78925242-3.33568871 C -0.88445694-1.14664037 0.05732157-0.42560052-2.43650101 0.25399715 H 0.53962761-2.69240066 0.40507249 C -1.52541179-3.27064112 0.27761753 C -2.61328665-2.41808055 0.08516136-2.20750214-1.11740749-0.04936209 C -1.65143426-4.67890235 0.45097875 C -0.58952957-5.58945751 0.64523351 C -0.86517722-6.93477423 0.79762563 C -2.19850801-7.37399000 0.75147809-3.22028820-6.53603350 0.56629927 C -2.97844043-5.20199385 0.42288179 C -4.12142481-4.32949205 0.23547392-5.36194600-4.90049931 0.24267461 C -6.43379479-4.12703522 0.06099748 C -6.34178862-2.73752856-0.12858724 C -5.09797905-2.13433703-0.12658830 C -3.95094523-2.93228084 0.05817998 H 0.43746777-5.23630107 0.67525256 H -0.06994528-7.65658434 0.95050567 H -2.45631136-8.42199266 0.86293470 H -7.39256614-4.63528869 0.07259369 H -7.24838980-2.15869480-0.27022540 H -4.97995030-1.06425489-0.26270991 Ir -5.36922243-7.09945854 0.52828621 C -7.84611459-7.52292099-0.96638331 C -7.37167217-7.38237229 0.36688044 C -8.32306804-7.41771378 1.39788637 C -9.68428759-7.57716154 1.12384402 C -10.13549525-7.70884225-0.19401004 C -9.21669008-7.68270372-1.23714032 H -8.00511131-7.32945055 2.43298323 H -10.39794089-7.60493489 1.94356320 H -11.19348268-7.83494917-0.40272821 H -9.57165883-7.78893090-2.25863877 C -6.81859694-7.49084448-2.00624930-5.54386899-7.30561055-1.54238014 C -4.51117803-7.27108786-2.40845502 C -4.67743617-7.41317532-3.77764829 C -5.97192558-7.59912547-4.27314694 C -7.03803147-7.63710761-3.38516387 H -3.53094892-7.13290252-1.96797064 H -3.81440112-7.38174269-4.43357424 H -6.14423397-7.71597394-5.33888630 H -8.04710102-7.78574478-3.75128204 C -5.12715799-9.07956961 0.90177911 C -5.02643114-9.41573534 2.28005705 C -4.81351365-10.74359519 2.69077529 C -4.70031703-11.75680327 1.74529020 C -4.80210373-11.44363182 0.38544812 C -5.01330700-10.12510135-0.02746728 H -4.73764316-10.99265439 3.74576546 H -4.53912700-12.78258277 2.06252936 H -4.72272017-12.23356232-0.35736423 H -5.09929787-9.91742006-1.09046770 C -5.16216941-8.29677260 3.21220997-5.34214096-7.07713880 2.61669772 C -5.49419894-5.97321489 3.37584477 S11
C -5.47236317-6.00956591 4.76187363 C -5.28491350-7.24455528 5.39052232 C -5.13030735-8.38403374 4.61291811 H -5.64542924-5.04610667 2.83594866 H -5.60288177-5.09434020 5.32876642 H -5.26394236-7.31559128 6.47389156 H -4.99057633-9.35010318 5.08364144 Compound 2 + : E = -3430.27012742 au C 0.00000000 0.00000000 0.00000000 C 1.43117950 0.00000000 0.00000000 C 1.88190076 1.35306771 0.00000000 C 0.73019785 2.19822076-0.03654448 C -0.42572110 1.36482879-0.05953639 H 2.07452360-0.87142761-0.00807853 H 2.91490413 1.67534447 0.02449578 H 0.73049349 3.28058773-0.03703971 H -1.45811921 1.68610481-0.09534264 Fe 0.80198868 1.03392023-1.74661354 C -0.29763648 0.79955215-3.49160768 C 0.21335126 2.13214073-3.45851759 C 1.63392061 2.06163199-3.44732711 C 2.00990244 0.69125446-3.46151043 C 0.81863499-0.09501115-3.49280199 H -1.34278970 0.51905403-3.50968743 H -0.37594278 3.04004926-3.42927522 H 2.31085249 2.90508004-3.38841080 H 3.02411899 0.31277082-3.43698689 H 0.77137834-1.17579363-3.52559763 C -0.90485174-1.13827526 0.03868684-0.53980810-2.39638929 0.47749267 H 0.35676307-2.65503483 0.86760701 C -1.67388249-3.17872312 0.44856182 C -2.67918575-2.33968943-0.03860940-2.18706193-1.08552021-0.28684513 C -1.89346626-4.54438618 0.81911509 C -0.91877186-5.43325223 1.31497435 C -1.28490793-6.72871620 1.63335148 C -2.61727001-7.12839037 1.44898251-3.55713262-6.30442480 0.97680450 C -3.22519684-5.02097522 0.66624052 C -4.28762435-4.15648928 0.17023863-5.53929978-4.68901898 0.08438552 C -6.53676267-3.92904519-0.37570018 C -6.35332857-2.59276398-0.76600100 C -5.09421669-2.02645776-0.67260818 C -4.02833108-2.81292827-0.19699644 H 0.11026000-5.11106558 1.44900095 H -0.56141309-7.43807792 2.02035767 H -2.94556220-8.13627201 1.68249157 H -7.51043614-4.40616826-0.42495323 H -7.20160543-2.02228103-1.12901208 H -4.91463100-0.99394008-0.95370296 Ir -5.71117553-6.81764132 0.71667233 C -7.98780029-7.41489847-1.01694883 C -7.68670225-7.06035868 0.32652332 C -8.76313890-6.88228146 1.20761792 C -10.08412079-7.04051299 0.77711368 C -10.36552933-7.38398012-0.54934830 C -9.31841031-7.57184896-1.44450575 H -8.58051117-6.62869057 2.24772880 H -10.89899363-6.90254951 1.48305343 H -11.39236013-7.50953308-0.87816983 H -9.54274521-7.84331911-2.47221927 C -6.83320421-7.60630484-1.89212580-5.62156681-7.37554894-1.29740493 C -4.48402021-7.54389568-2.00239356 C -4.47712714-7.94116139-3.33022832 C -5.70497569-8.17578415-3.95890231 C -6.87822507-8.00667276-3.23748919 H -3.56252167-7.36316029-1.46126305 H -3.53563886-8.07185422-3.85236110 H -5.74282552-8.49369552-4.99642000 H -7.83716437-8.19435523-3.70585816 C -5.62092020-8.71714007 1.42480767 C -5.73068678-8.82970220 2.83794044 C -5.63821420-10.07997583 3.47504067 C -5.44016369-11.23310605 2.72361308 C -5.33626336-11.13868512 1.33197885 C -5.42645811-9.89785811 0.69328215 H -5.72359371-10.16024490 4.55508291 S12
H -5.37374258-12.19865493 3.21514309 H -5.19231793-12.03850761 0.73949037 H -5.35606460-9.86273319-0.38998779 C -5.95134351-7.57514632 3.55542735-5.98033018-6.46050533 2.76071153 C -6.20237555-5.24851751 3.30990916 C -6.39926077-5.06728667 4.66994968 C -6.36602475-6.19244017 5.50086832 C -6.14172732-7.44209998 4.94026054 H -6.23351975-4.41507649 2.61797618 H -6.58222555-4.07343575 5.06343832 H -6.52085334-6.09375659 6.57101600 H -6.12402446-8.32509153 5.56810885 Compound 3 2eq/2ax (singlet): E = -1781.05246273 au E = -1781.45546358 au (method B) H 0.00000000 0.00000000 0.00000000 C 1.08167239 0.00000000 0.00000000 1.80703970 1.16729754 0.00000000 H 1.41954609 2.10103026 0.00063764 C 3.14076551 0.80942602 0.00027822 C 3.13141100-0.58397098 0.00017996 1.84410598-1.06994274 0.00007617 C 4.33888435 1.58768001-0.00353578 C 4.41182693 2.99605396-0.00863159 C 5.64943086 3.61260471-0.01590820 C 6.80963713 2.82302698-0.02431681 6.76775886 1.48878785-0.02310845 C 5.56087364 0.85543351-0.00448000 C 5.56702381-0.59717778 0.00911818 6.77936479-1.22375293 0.03048542 C 6.81957601-2.55780112 0.03033253 C 5.65974437-3.35073937 0.01831002 C 4.41982683-2.73890392 0.00917711 C 4.35467445-1.33138323 0.00511361 H 3.50488204 3.59416315-0.00646448 H 5.73785146 4.69370916-0.01761169 H 7.79950245 3.26737131-0.03547322 H 7.80971291-3.00180435 0.04384871 H 5.75383862-4.43153450 0.01905693 H 3.49823461-3.31183951 0.00465429 Ir 8.53241031 0.13724477 0.01098516 C 10.28886358-1.76344437-1.34891587 C 9.97587343-1.28682458-0.04624956 C 10.65687997-1.86635607 1.03504777 C 11.60087256-2.87838018 0.83910695 C 11.89399288-3.34006292-0.44864714 C 11.23908553-2.78205473-1.54081280 H 10.46101605-1.52328912 2.04702112 H 12.11598669-3.30596021 1.69570148 H 12.62966789-4.12459995-0.59700075 H 11.47285153-3.14172432-2.53913093 C 9.56247919-1.12320924-2.44465390 8.66387144-0.16799257-2.05161067 C 7.94434388 0.49945612-2.97616912 C 8.06684833 0.26007379-4.33629901 C 8.97590907-0.71501292-4.75909886 C 9.72052424-1.40319176-3.81123645 H 7.26271135 1.24921825-2.59242767 H 7.46778578 0.82567656-5.04144951 H 9.10253185-0.93138102-5.81561794 H 10.43343003-2.15804576-4.12151874 C 9.96335635 1.57414175 0.08558312 C 10.25942893 2.05008210 1.39268333 C 11.19853182 3.07658177 1.59683254 C 11.85912058 3.64365090 0.51265660 C 11.58290505 3.18311071-0.77927274 C 10.64986821 2.16327605-0.98720835 H 11.41966884 3.43516823 2.59844920 H 12.58664873 4.43393209 0.67055058 H 12.10314706 3.61733864-1.62942938 H 10.46744258 1.82046543-2.00188583 C 9.52893519 1.39929142 2.47993347 8.64062198 0.43921275 2.07538449 C 7.91991950-0.23977308 2.99070152 C 8.03092725-0.00682855 4.35308677 C 8.92910118 0.97307097 4.78770742 C 9.67495400 1.67281657 3.84907511 S13
H 7.24822396-0.99366110 2.59772388 H 7.43225542-0.58217062 5.05065612 H 9.04725953 1.18370639 5.84638815 H 10.38048830 2.43065182 4.16889138 Compound 3 3eq/1ax (singlet): E = -1781.05051127 au E = -1781.45354592 au (method B) H 0.00000000 0.00000000 0.00000000 C 1.08165761 0.00000000 0.00000000 1.80709098 1.16711621 0.00000000 H 1.42005507 2.10102496 0.00569877 C 3.14061515 0.80930879 0.00101813 C 3.13120873-0.58474602 0.00099991 1.84398471-1.07007538-0.00014615 C 4.33954554 1.58584547 0.00191081 C 4.42580735 2.99321445 0.00647051 C 5.67041799 3.59722369 0.01117479 C 6.82345290 2.79737999 0.00620856 6.76857342 1.46498271-0.00466222 C 5.55567293 0.84660431 0.00112610 C 5.56196789-0.59995130 0.01259820 6.78161516-1.22435001 0.03830556 C 6.82056081-2.56174618 0.05700072 C 5.65942810-3.34957058 0.05025271 C 4.41747924-2.74239764 0.02819275 C 4.35294807-1.33591212 0.01117630 H 3.52546436 3.60097321 0.01045072 H 5.76840661 4.67741003 0.02124869 H 7.81538143 3.23674414 0.01516652 H 7.80782242-3.00604800 0.08685078 H 5.75730183-4.42975982 0.06741937 H 3.49728134-3.31723727 0.02754998 Ir 8.44263456 0.04150139 0.05808988 C 10.19746005-1.89103618-1.32605309 C 9.84849570-1.43861040-0.02071847 C 10.49256958-2.04961015 1.06748890 C 11.43695785-3.06322551 0.88231489 C 11.76955530-3.49678844-0.40465628 C 11.15046874-2.91161982-1.50329980 H 10.25376862-1.73186333 2.07767823 H 11.91727504-3.51485746 1.74672731 H 12.50496790-4.28253923-0.54884772 H 11.41604417-3.25358957-2.49958917 C 9.51195425-1.25286325-2.45834913 8.62916826-0.26922858-2.12089262 C 7.94160983 0.37712985-3.08014887 C 8.08775714 0.09574111-4.43148962 C 8.98967075-0.90798125-4.79883991 C 9.69915722-1.58072864-3.81261862 H 7.25727148 1.14595000-2.73472975 H 7.51310206 0.64463296-5.16960323 H 9.13573929-1.16269697-5.84442261 H 10.39740043-2.36236091-4.08730627 C 8.48664197 0.27330380 2.08229289 C 9.45568015 1.20283228 2.54867086 C 9.59603706 1.48237801 3.91930328 C 8.77915896 0.84645312 4.84772355 C 7.82050647-0.07181610 4.40614148 C 7.67781188-0.35090582 3.04392546 H 10.34123385 2.19221193 4.26799708 H 8.88874852 1.06009600 5.90657637 H 7.18267048-0.57508235 5.12868283 H 6.92936560-1.07729499 2.73721547 C 10.28682459 1.81500544 1.51286999 9.98620898 1.42491204 0.23451462 C 10.69920427 1.90866996-0.80366516 C 11.73572416 2.81498626-0.63955840 C 12.05487903 3.23249474 0.65610823 C 11.32926055 2.73009812 1.72764647 H 10.41539897 1.54133767-1.78215897 H 12.28066705 3.17391377-1.50564181 H 12.86373102 3.93666943 0.82633989 H 11.56893618 3.03583429 2.73928945 S14
Compound 3 4eq (singlet): E = -1781. 03499102 au E = -1781.43748633 au (method B) H 0.00000000 0.00000000 0.00000000 C 1.08163801 0.00000000 0.00000000 1.80698282 1.16706215 0.00000000 H 1.42013425 2.10107743 0.00141274 C 3.14039229 0.81038109 0.00034667 C 3.13111712-0.58509579 0.00010754 1.84409038-1.06998899 0.00000000 C 4.33676823 1.59322567-0.00039262 C 4.42700264 2.99859751-0.00304074 C 5.67779079 3.59272917-0.00477757 C 6.82978815 2.79640706-0.00405164 6.77175598 1.45914140-0.00349693 C 5.54747271 0.84983866 0.00058912 C 5.55412053-0.58718506 0.00457733 6.78357889-1.18777956 0.01232524 C 6.84408533-2.52420456 0.01150977 C 5.69407852-3.32651614 0.00809304 C 4.44008215-2.73917645 0.00379891 C 4.35391525-1.33505480 0.00215012 H 3.53124754 3.61257521-0.00313296 H 5.78316121 4.67215307-0.00542133 H 7.82021755 3.23365441-0.00417644 H 7.83604195-2.95850528 0.01422440 H 5.80701337-4.40534562 0.00783279 H 3.53088551-3.33096282 0.00120065 Ir 8.36590370 0.14312193 0.01041429 C 10.23998086-1.67038313-1.41322578 9.87768745-1.30284631-0.14219542 C 10.50435706-1.84850848 0.92329519 C 11.51652619-2.78762919 0.79383968 C 11.90262423-3.17659641-0.49171151 C 11.26282307-2.61647430-1.58893285 H 10.16316475-1.50658412 1.89235845 H 11.98730760-3.19676069 1.68088554 H 12.69343409-3.90691983-0.63518968 H 11.55240664-2.90589093-2.59201967 C 9.49528206-1.01850192-2.49669795 C 8.51671558-0.07306364-2.09019912 C 7.79032936 0.56814485-3.10507299 C 8.01670859 0.29385864-4.45817705 C 8.98690071-0.64046574-4.83585043 C 9.72594632-1.29684709-3.85680853 H 7.02762555 1.30113551-2.84543662 H 7.43619209 0.80709581-5.22120121 H 9.16381238-0.85482933-5.88554731 H 10.47528386-2.02225979-4.16196083 9.86687091 1.60041392 0.17873605 C 10.21495476 1.96785891 1.45380504 C 11.23324873 2.91684911 1.64079935 C 11.88301514 3.47940286 0.55068324 C 11.51164529 3.09014354-0.73916066 C 10.50350954 2.14822455-0.87971231 H 11.51235735 3.20558883 2.64705748 H 12.67074267 4.21129559 0.70295623 H 11.99132355 3.50045448-1.62089553 H 10.17416876 1.80485563-1.85244782 C 9.46215508 1.31178150 2.52929203 C 8.49449533 0.35922024 2.11293582 C 7.76198000-0.28726909 3.12014176 C 7.97254256-0.01126648 4.47545764 C 8.93202246 0.93019287 4.86307487 C 9.67657632 1.59187785 3.89181832 H 7.00828796-1.02644353 2.85247771 H 7.38849729-0.52946844 5.23239197 H 9.09697039 1.14527215 5.91459683 H 10.41780705 2.32231235 4.20480008 S15
References.- 1.- Gaussian 03, Revision B.03, Frisch, M. J.; Trucks, G. W.; Schlegel, H. B.; Scuseria, G. E.; Robb, M. A.; Cheeseman, J. R.; Montgomery, Jr., J. A.; Vreven, T.; Kudin, K..; Burant, J. C.; Millam, J. M.; Iyengar, S. S.; Tomasi, J.; Barone, V.; Mennucci, B.; Cossi, M.; Scalmani, G.; Rega,.; Petersson, G. A.; akatsuji, H.; Hada, M.; Ehara, M.; Toyota, K.; Fukuda, R.; Hasegawa, J.; Ishida, M.; akajima, T.; Honda, Y.; Kitao, O.; akai, H.; Klene, M.; Li, X.; Knox, J. E.; Hratchian, H. P.; Cross, J. B.; Bakken, V.; Adamo, C.; Jaramillo, J.; Gomperts, R.; Stratmann, R. E.; Yazyev, O.; Austin, A. J.; Cammi, R.; Pomelli, C.; Ochterski, J. W.; Ayala, P. Y.; Morokuma, K.; Voth, G. A.; Salvador, P.; Dannenberg, J. J.; Zakrzewski, V. G.; Dapprich, S.; Daniels, A. D.; Strain, M. C.; Farkas, O.; Malick, D. K.; Rabuck, A. D.; Raghavachari, K.; Foresman, J. B.; Ortiz, J. V.; Cui, Q.; Baboul, A. G.; Clifford, S.; Cioslowski, J.; Stefanov, B. B.; Liu, G.; Liashenko, A.; Piskorz, P.; Komaromi, I.; Martin, R. L.; Fox, D. J.; Keith, T.; Al-Laham, M. A.; Peng, C. Y.; anayakkara, A.; Challacombe, M.; Gill, P. M. W.; Johnson, B.; Chen, W.; Wong, M. W.; Gonzalez, C.; and Pople, J. A.; Gaussian, Inc., Wallingford CT, 2004. 2.- Bartolottiand, L. J.; Fluchick, K. In Reviews in Computational Chemistry, Lipkowitz. K. B; Boyd, B. D., Eds.; VCH, ew York, 1996; Vol. 7, pp. 187-216. S16