Interligand charge transfer in a complex of deprotonated cis-indigo dianions and tin(ii) phthalocyanine radical anions with Cp*Ir(III).

Transcription

1 Interligand charge transfer in a complex of deprotonated cisindigo dianions and tin(ii) phthalocyanine radical anions with Cp*Ir(III). Dmitri V. Konarev,*, Leokadiya V. Zorina, Salavat S. Khasanov, Alexander F. Shestakov, Alexey M. Fatalov,, Akihiro Otsuka,, Hideki Yamochi,, Hiroshi Kitagawa, and Rimma N. Lyubovskaya Institute of Problems of Chemical Physics RAS, Chernogolovka, Moscow region, Russia; Institute of Solid State Physics RAS, Chernogolovka, Moscow region, Russia; Moscow State University, Leninskie Gory, Moscow, Russia; Division of Chemistry, Graduate School of Science, Kyoto University, Sakyoku, Kyoto , Japan; Research Center for Low Temperature and Materials Sciences, Kyoto University, Sakyoku, Kyoto , Japan. S1

2 Schemes for the formation of 1 and 2. S2

3 Theoretical calculations Theoretical calculations were performed using the PBE density functional method 1 and Λ2 basis 2 of ccpvtz quality. All calculations were performed using the PRIRODA program package 3 at Joint Supercomputer Center of the Russian Academy of Sciences. Atomic distribution of charge was determined by the Hirschfeld method. 4 This level of theory allows the structure of complex 1 (Fig. S2a) and its IR spectrum to be described well (Fig. S3). The geometry of (cisindigon,n) 2 ligand in the complex differs from the geometry of free of cisindigo dianion (Fig. S1a). Coordination of indigo to the Ir center by carbonyl groups (Fig. S2b) leads to less stable isomeric structure. The great difference in energy, 40.5 kcal/mol, is due to stronger IrN bonds. Intermolecular electron transfer is similar in both complexes. There are the same dipole moment 11.9 D and comparable charges on the Ir center 0.16 (1) and 0.21 (isomer). Separate [Sn II (Pc 3 )]{(cisindigon,n) 2 Cp*Ir III } (cish 2 Indigo) (I) (Fig. S4a) and (cis H 2 Indigo){cisindigoN,N) 2 Cp*Ir III }[Sn II (Pc 3 )] (II) (Fig. S4b) complexes which differ in orientation of leuco cisindigo relatively the cisindigo 2 ligand demonstrate good correspondence of calculated and experimental short contacts (see main text). A {[Sn II (Pc 3 )](cisindigo N,N) 2 Cp*Ir III } (cish 2 Indigo){(cisindigoN,N) 2 Cp*Ir III [Sn II (Pc 3 )]} (IV) complex which takes into account both Ir centers and bridging leuco cisindigo molecule (but without counterions) worse describes one short N...O contact (Fig. S5b). It becomes 3.6 Å and almost disappears. The reason is the distortion of the structure due to the effect of noncompensated Coulomb repulsion. It is seen from longer SnSn distance of 20.5 Å with respect to the experimental one (19.7 Å) in the crystal structure of 2. That is why the total interaction energy of three units in IV is only 17.5 kcal/mol, which is much lower than the sum of interaction energy in separate complexes (I) and (II), 49.5 kcal/mol. The large decrease on 22 kcal/mol is comparable with Coulomb repulsion energy, 16.2 kcal/mol, of two point charges separated by 20.5 Å. Complex IV has a triplet ground state. Singlet state in the complex is higher in energy by 3.4 kcal/mol, and its geometry is almost the same as for triplet state. In the isolated {[Sn II (Pc 3 )] (cisindigon,n) 2 Cp*Ir III } (Fig. S6) unit the geometry of coordination polyhedron is practically the same as in trimolecular complex (IV) (Fig. S5b). The only difference in structure of the ligands in IV is the elongation of CO bond and shortening of neighboring CO bond in (cisindigon,n) 2 as result of strong hydrogen bond formation. In neutral {(cisindigon,n) 2 Cp*Ir III }(cish 2 Indigo){cisindigoN,N) 2 Cp*Ir III } trimolecular complex (III) (Fig. S5a) with removed Sn II (Pc 3 )] ligands, optimization leads to transfer of one proton of the leuco cisindigo molecule to the cisindigo 2 ligand. It does not change much short O...O contact of Å but leads to strong elongation of one short N...O contact to 3.6 Å. In calculated structure CO bond lengths of the cisindigo 2 ligand correlate with OH hydrogen bond length in the S3

4 C=O...H...O fragment and vary from to Å. The CO bond length Å in the carbonyl group not involved in hydrogen bonds is slightly shorter than that in free (cisindigo) 2 dianion, Å. From the results obtained allow us to conclude that intermolecular hydrogen bonds are quite sensitive to the Coulomb fields and for their adequate modeling solid structure calculations are necessary. a b Fig. S1. The calculated structure of cisindigo dianion (a); and (cisindigo) 3 radical trianion (b). a b Fig. S2. The calculated structure of complex (cisindigon,n) (Cp*Ir III ) (a) and its isomer (cisindigo O,O) (Cp*Ir III ) (b). S4

5 Fig. S3. The calculated IR spectrum of complex 1 in the cm 1 range. S5

6 a b Figure S4. Calculated structure of complexes: (a) [Sn II (Pc 3 )]{(cisindigon,n) 2 Cp*Ir III } (H 2 Indigo) (I) and (b) (H 2 Indigo){cisindigoN,N) 2 Cp*Ir III }[Sn II (Pc 3 )] (II). The H atoms of Pc and indigo ligands are omitted for clarity. The bond lengths of short contacts are shown in Å. S6

7 a b Fig. S5. The calculated structure of trimolecular complexes: (a) neutral {(cisindigon,n) 2 Cp*Ir III } (H 2 Indigo){cisindigoN,N) 2 Cp*Ir III } (III) and (b) the {[Sn II (Pc 3 )](cisindigo N,N) 2 Cp*Ir III } (H 2 Indigo){cisindigoN,N) 2 Cp*Ir III [Sn II (Pc 3 )]} dianion (IV). The H atoms of Pc and indigo ligands are omitted for clarity. The bond distances are shown in Å. S7

8 Fig. S6. The calculated structure of the {[Sn II (Pc 3 )](cisindigon,n) 2 Cp*Ir III } (V) complex. The H atoms of Pc and indigo ligands are omitted for clarity. The bond lengths are shown in Å and only averaged IrC distance is given. S8

9 IR spectra. Table S1. IRspectra (cm 1 in KBr) of pristine compounds and complexes 1 and 2. Components trans Indigo {cryptand(na + )} [Sn II (Pc 3 )] C 6 H 4 Cl 2 (Bu 4 N + )(Br ) {(cisindigon,n) (Cp*Ir III )} (1) ( Bu 4 N + ) 2 {[Sn II (Pc 3 )](cisindigon,n)(cp*ir III )} 2 0.5(H 2 Indigo) 2.5C 6 H 4 Cl 2 (2) Cp*Ir 447w 576w 920s 1023w 1237w 1317w* 1373w* 1453s* 2905w 2963w 2985w 1032m* 1234w* 1304m 1379w* 1441s 2918m 2958w* Bu 4 N + [Sn II (Pc 3 )] 437w 497w 629w 717s 747s* 766m 818w 886w* 942w* 1072s* 1116s* 1286m* 1332m 1418w 1457s* 1501w* 3053w 738s 883s 896s 922s 992s 1031m 1059m 1069m 1110s 1166s 1240m 1365m 1379m 1455s 1464s 1474s 2873w 2959w 726m 890w* 912w* 1004m* 1032m* 1073m* 1115s* 1165m 1234w 1330s 1379w* 1441s* 1462m* 1472m* 2874w 2958w 712s* 746s* 823w 890w* 1073m* 1115s* 1330s 1418m* 1441s* 3051w* Indigo 563w 643w 699w 714w 566w 697m 718w 562w 658w 712s* S9

10 Solvent 745w sh 755m 859w 879w 1012w 1071s 1096w 1107w 1129s 1173s 1200s 1298m 1318m 1392m 1409w sh 1462s 1483m 1586m 1613s 1627s 3040w 3058w 3250m 3270m 756m 1023w 1090m 1125s 1180s 1291s 1317w* 1453s* 1470w 1563m 1607m 1652m 1658vs 3060w *Bands are overlapped, w weak intensity, m middle intensity, s strong intensity, sh shoulder 746s* 890w* 1004m* 1073m* 1098s 1115s* 1178m 1291w 1379w* 1418m* 1462m* 1472m* 1527s 1604s 1658m 3051w Hydrogen bonds 2586w 2621w 2754w 3432m C 6 H 4 Cl 2 658w 746s* 1032m* 1462m S10

11 Fig. S7. IR spectrum of pristine transindigo in KBr pellet. Fig. S8. IR spectrum of {(cisindigon, N)(Cp*Ir III )} (1) in KBr pellets prepared in anaerobic conditions. S11

12 Fig. S9. IR spectrum of (Bu 4 N + ) 2 {[Sn II (Pc 3 )] (cisindigon,n)(cp*ir III )} 2 0.5(H 2 Indigo) 2.5C 6 H 4 Cl 2 (2) in KBr pellets prepared in anaerobic conditions. S12

13 Fig. S10. IR spectrum of (Bu 4 N + ) 2 {[Sn II (Pc 3 )] (cisindigon,n)(cp*ir III )} 2 0.5(H 2 Indigo) 2.5C 6 H 4 Cl 2 (2) in the range of the CH, OH and NH vibrations. KBr pellets were prepared in anaerobic conditions. Transindigo shows absorption bands of the NH vibrations at 3250 and 3270 cm 1 which disappear in the spectrum of 1 due to deprotonation. Spectrum of 2 in the range of the CH and NH vibrations is shown in Fig. S10. The absorption bands of the CH vibrations are positioned at cm 1. New bands observed at 2586 and 2621 cm 1 can be attributed the the O H O=C hydrogen bonds. The NH vibrations involved in weak hydrogen bonding can contribute to a broad intense band at 3432 cm 1 (Fig. S10). That is confirmed by calculations (see next section). S13

14 Table S2 Theoretical absorption bands calculated for the CH, NH, OH vibrations in individual leuco cisindigo and most intense IR vibrations of the complex 1 cisindigomg leuco cisindigo ν, cm 1 μ I, km/mol СН CH vibrations vibrations ν, 3106 cm μ I, km/mol ОН vibrations NН vibrations Complex 1 ν, cm 1 μ, a.u.m I, km/mol S14

15 * * CH vibrations of indigo ligand * CO vibrations S15

16 Crystal structures Fig. S11. View on the coordination {[Sn II (Pc 3 )](cisindigon,n)(cp*ir III )} unit along the IrSn bond. Indigo and Cp* ligands are shown by blue and green colours, respectively. S16

17 Magnetic properties SQUID data b a Fig. S12. Temperature dependencies of effective magnetic moment (a) and reciprocal molar magnetic susceptibility of 2 (b). S17

18 EPR data Fig. S13. Plot of lnk vs reverse temperature (1/T). The slope of the dependence ( G o /R = 1115±22, where R is a gas constant equal to (26) J/(mol K)) allows the estimation of the Gibbs energy of electron transfer between two ligands in 2. K is an equilibrium constant of the reaction of electron transfer: [Sn II (Pc 3 )] + (cisindigo) 2 [Sn II (Pc 2 )] 0 + (cisindigo) 3 References 1. Perdew, J. P.; Burke, K.; Ernzerhof, M. Generalized Gradient Approximation Made Simple Phys. Rev. Lett. 1996, 77, Laikov, D. N. A new class of atomic basis functions for accurate electronic structure calculations of molecules. Chem. Phys. Lett., 2005, 416, Laikov, D. N. Fast evaluation of density functional exchangecorrelation terms using the expansion of the electron density in auxiliary basis sets. Chem. Phys. Lett., 1997, 281, Hirshfeld, F. L. Bondedatom fragments for describing molecular charge densities. Theor. Chim. Acta 1977, 44, S18