Inorg. Chem. 1992, 31, 3737-3748
3737
Mono- and Dinuclear Titanium(III)/Titanium( IV) Complexes with 1,4,7-Trimethyl-1,4,7-triazacyclononane (L). Crystal Structures of a Compositionally Disordered Green and a Blue Form of [LTiCl3]. Structures of [LTi(O)(NCS)z], [LTI(OCH3)Brz](C1O4),and
[LzTiz(O)zFz(cl-F)](PFs) Axel Bodner," Peter Jeske," Thomas Weyhermiiller,la Karl Wieghardt,'J* Erich Dubler,lb Helmut Schmalle,lb and Bernhard NubertC Lehrstuhl fur Anorganische Chemie I, Ruhr-Universitat, D-4630 Bochum, Germany, Institut fur Anorganische Chemie der Universitat, CH-8057 Zurich, Switzerland, and Anorganische-Chemisches Institut der Universitat, D-6900 Heidelberg, Germany Received February 5, 1992
The coordination chemistry of titanium(II1) and -(IV) with the macrocycle 1,4,7-trimethyl- 1,4,7-triazacyclononane (L, CgHzlN3)has been investigated. Reaction of Tic13 with L in CH3CN at 20 OC affords blue [LTiC13](1) whereas at elevated temperature green crystals (la) were obtained. l a is shown to consist of compositionally disordered crystals containing [LTi111C13] and probably an [LTi1V(0)C12]impurity. The crystal structures of 1 and la have been determined. Crystal data for 1 and, in brackets, for la: space group P2l/c (P21/c), a = 12.365 ( 5 ) A (12.430 (8) A), b = 7.348 (2) A, (7.337 (3) A), c = 15.897 (3) A (15.929 ( 5 ) A), j3 = 90.06 (2)' (90.19 (3)O), V = 1443 (1) A3 (1453 (2) A3) Z = 4 (4). It has been possible to detect the impurity in l a by comparing the temperature parameters of the C1 atoms and the residual electron density maps of the final difference Fourier calculations of 1 and la. The structure of the [LTiW13] molecule is identical in both 1 and la; only slight differences of the packing are observed. Implications of this observation on the "distortional" or "bond stretch" isomerism phenomenon are discussed. Reaction of TiBr4 with L in CH3CN yields [LTiBr3] (2) whereas Tic14 reacts with L at 20 OC affording [LTiCl3]Cl(5). Complex 1 reacts with CF3S03H to give blue [LTi(03SCF3)3] (3)which is a good starting material for the synthesis of complexes containing the L T P fragment. Thus 3 reacts with NaSCN in CH30H to give [LTiIJl(NCS)3] (4). Oxidation of 1 by azide yields [LTiC12(N3)][BPh4] ( 6 ) whereas oxidation of 4 by 0 2 in the presence of water gives [LTilV(0)(NCS)2](7). Crystal data for 7: space group Pna21, a = 7.076 (2) A, b = 14.247 (3) A, c = 16.163 ( 5 ) A, V = 1629 (2) A3,Z = 4. Complex 7is the first structurally characterized octahedral complex of titanium(1V) containing a terminal oxo ligand (titanyl group): Ti=O 1.638 (3) A. Air oxidation of 2 in methanol yields [LTi1V(OCH3)Br2](C104)(8). Crystal data for 8: space group Pnma, a = 12.819 (3) A, b = 11.608 (2) A, c = 12.686 (3) A, V = 1888 (1) A3, Z = 4. Tic13 and the ligand L in water containing dimethylformamide form the p-oxo-bridged dinuclear species [L2Ti1112C14(p-0)] (9) which is oxidized by air to the mixed-valence species [ L ~ T ~ ~ C ~ ~ ( ~ L - O )(10) ] C Iand, . ~ Hfinally, ~ O to [L~Ti~~2C14(p-O)] C12.2.5H20 (1 1). Complete hydrolysis and air oxidation of 1 in water at pH 7 (NaHC03) yields colorless crystals of [L2Ti1V2(0)2(OH)2(p-O)]43H20 (12). When the hydrolysis/oxidation reaction of 1 is carried out in a water/nitromethane mixture in the presence of NaF, yellow crystals of [L2Ti2Fz(O)2(p-F)](PFs) (13) were obtained. Crystal data for 13: space group Pi, a = 7.676 (5) A, b = 7.695 (6) A, c = 13.67 (1) A, a! = 75.05 (6)O, j3 = 79.67 ( 6 ) O , y = 70.03 (6)O, V = 729 (1) A3, Z = 1.
Introduction In this paper we describe some preparative and structural coordination chemistry of the tridentate facially coordinating macrocycle 1,4,7-trimethyl-l,4,7-triazacyclononane (L)z with titanium(II1) and -(IV). Due to the inherent lability of Ti-N bonds toward hydrolysis and the greater thermodynamic stability of T i 4 bonds, only relatively few titanium complexes with amine ligands have been ~haracterized.~[(N4C,2H2~)2Ti2(p-0)] ((N4Cl2H25)3- = trianion of 1,5,9,13-tetraaza~yclohexadene),~~ [ T ~ ( C Z ~ H Z ~ Nand ~ ) C[L'4Ti4(p-0),l4+ ~~],~ 4b (L' = 1,4,7-triazacyclononane) have been reported; they are the first examples of structurally characterized titanium(1V) complexes containing macrocyclic amine ligands. ( I ) (a) Ruhr-Universitat Bochum. (b) Universitiit Zurich. (c) Universitat
Heidelberg. (a) Wieghardt, K.; Chaudhuri, P.; Progress in Inorgunic Chemistry; Lippard, S . J., Ed.; Wiley: New York, 1988; Vol. 35, p 329. (b) Bhula, R.; Osvath, P.; Weatherburn, D. C. Coord. Chem. Rev. 1988, 91, 89. McAuliffe, C. A.; Barrat, D. S. Comprehensive Coordinution Chemistry; Wilkinson, G., Gillard, R. D., McCleverty, J. A,, Edts.; Pergamon Press: Oxford, England, 1987; Vol. 3, p 323. (a) Olmstead, M. M.; Power, P. P.; Viggiano, M. J. Am. Chem. SOC. 1983,105,2927. (b) Wieghardt. K.; Ventur, D.; Tsay, Y. H.; Kruger, C. Inorg. Chim. Acra 1985, 99, L25. (c) Goedken, V. L.; Ladd, J. A. J . Chem. SOC.,Chem. Commun. 1982, 142
During the course of the present investigation we made a serendipitous discovery which bears relevance to the possibility of an experimental verification of so-called "distorti~nal"~-~ or "bond stretch"9Jo isomers by X-ray crystallography."J2 It was found that the reaction between L and Tic13 in acetonitrile at room temperature under anaerobic conditions produced nice blue crystals of [LTi111C13].When the reaction was carried out with heating to reflux under otherwise idenicalconditions,green crystals which apparently also analyzed as [ LTi1I1Cl3] were obtained. (a) Chatt, J.; Manojlovic-Muir, L.; Muir, K. W. J. Chem. SOC.D 1971, 655. (b) Butcher, A. V.; Chatt, J. J. Chem. SOC.A 1970, 2652. (a) Backes-Dahmann, G.; Wieghardt, K.; Nuber, B.; Weiss, J. Angew. Chem., Int. Ed. Engl. 1985, 24, 777. (b) Backes-Dahmann, G.; Wieghardt, K. Inorg. Chem. 1985, 24, 4044. (7) (a) Bashall, A.; McPartlin, M. Acto Crystallogr. 1990,46A, (2-221. (b) Bashall, A.; Gibson, V. C.; Kee, T. P.; McPartlin, M.; Robinson, 0.B.; Shaw, A. Angew. Chem., Int. Ed. Engl. 1991, 30, 982. Degnan, I. A.; Behm, J.; Cook, M. R.; Herrmann, W. A . Inorg. Chem. 1991, 30, 2165. (9) Yves, J.; Lledos, A.; Burdett, J. K.; Hoffmann, R. J. Am. Chem. SOC. 1988, I IO, 4506. (IO) Song, J.; Hall, M. B. Inorg. Chem. 1991, 30, 4433. ( I 1) Yoon, 1 Al7 K.; Parkin, G.; Rheingold, A. L. J . A m . Chem. SOC.1991, 113,
. ._..
(12) Desroches, P. J.; Nebesny, K. W.; LaBarre, M. J.; Lincoln, S . E.; Loehr, T. M.; Enemark, J. H. J. A m . Chem. SOC.1991, 113, 9193.
0020-1669/92/1331-3737$03.00/0 0 1992 American Chemical Society
3138 Inorganic Chemistry, Vol. 31, No. 18, 1992 Careful spectroscopic analysis of this green material led to the conclusion that the green crystals are compositionally disordered by ca. 10% with presumably [LTiIV(0)C12]. To our amazement, high-quality X-ray structure determinations of both a blue and a green crystal revealed only a weak indication of an impurity in the latter. Since the octahedral species [LTi(O)C12] containing a Ti=O group (titanyl group) is the presumed impurity, we have studied the hydrolysis reaction of [LTiC13]under anaerobic and oxidative conditions in an attempt to isolate a pure sample of [LTi(O)C12]. The resulting dinuclear oxo-bridged complexes are described here. Some aspects of this work have been communicated p r e v i o ~ s l y . ~ ~ Structurally characterized octahedral titanyl complexes are unknown to date due to the propensity of oxotitanium(1V) complexes to form bridges of the type Ti-O-Ti.3 Only a few titanyl complexes where the Ti(1V) ion is or sevencoordinate19 have been structurally characterized. The existence of such species in solution has been implied by infrared, Raman,20 and 1 7 0 NMR Although we have not been able to prepare [LTi(O)C12], we succeeded in synthesizing its closely related analogue [LTi(O)(NCS)2]. Finally, we have synthesized two dinuclear titanium(1V) complexes which in addition to an oxo or fluoride bridging group contain terminal oxo groups, (Ti=O). Complexes of type I are very common for the higher oxidation states of vanadium, molybdenum, tungsten, and rhenium but were not known for titanium.
I
P
Experimental Section Reagents. The ligand 1,4,7-trimethyl- 1,4,7-triazacycIononane(L) was prepared according to a published procedure.22 The solvent acetonitrile was purchased from Baker ([H20] = 0.1%) and was used as received. (LTiCla] (Blue) (1). An argon-purged mixture of TiCI3 (1.0 g, 6.5 mmol) in acetonitrile (25 mL) was heated to reflux for 30 min. After the suspension was allowed to cool to room temperature, a solution of 1,4,7-trimethyl-1,4,7-triazacycIononane (1.2 g, 7.0 mmol)in acetonitrile (10 mL) was added dropwise. The mixture was stirred at 20 OC for 30 min under an argon blanketing atmosphere. A blue solid precipitated which was collected by filtration, washed with dry diethyl ether, and air-dried. Yield: 2.0 g; 92%. The product is stable for weeks in dry air. Anal. Calcd for C ~ H ~ I N ~ CC, I ~33.2; T ~ H, : 6.5; N, 12.9; CI, 32.6; Ti, 14.8. Found: C, 33.8; H, 6.7; N , 12.9; CI, 32.4; Ti, 15.1. [LTiCla] (Green) (la). Method A. When the above reaction between the blue solution and the ligand L was carried out with heating to reflux under anaerobic conditions (argon blanketing atmosphere) a green precipitate formed immediately. Yield: 1.7 g. It was found that the color of this material varied from blue-green to light green depending on the amount of water in the solvent acetonitrile (=2-5%) and probably on the adventitious presence of oxygen. The less of each present the more bluish was the product obtained. (13) Bodner, A,; Della Vedova, S. P. C.; Wieghardt, K.; Nuber, B.; Weiss, J. J . Chem. SOC.,Chem. Commun. 1990, 1042. (14) Guilard, R.; Latour, J. M.; Lecomte, C.; Marchon, J.-C.; Protas, J.; Ripll, D. Inorg. Chem. 1978, 17, 1228. ( 1 5 ) Dwyer, P. N.; Puppe, L.; Buchler, J. W.; Scheidt, W. R. Inorg. Chem. 1975 - - . -, .l d., 17x7 .. - -. (16) Hiller, W.; Strahle, J.; Kobel, W.; Hanack, M. 2.Kristalfogr. 1982, 159, 173. (17) Feltz, A. Z . Chem. 1967, 7 , 158. (18) Dehnicke, K.; Pausewang, G.; Riidorff, W. Z. Z . Anorg. Allg. Chem. 1969, 366, 64. Peng-Ju, L.; Sheng-Hua, H.; Kun-Yao, H.; Ru-Ji, W.; Mak, C. W. Inorg. Chim. Acta 1990, 175, 105. Gratzel, M.; Rotzinger, F. P. Inorg. Chem. 1985, 24, 23 20. Comba, P.; Merbach, A. Inorg. Chem. 1987, 27, 1315. Wieghardt, K.; Chaudhuri, P.; Nuber, B.; Weiss, J. Inorg. Chem. 1982. 21, 3086.
Bodner et al. Method B. A deoxygenated acetonitrile solution (20 mL) of Tic14 (1 .O g, 5.3 mmol) was heated to reflux until a clear, green solution was obtained. To this solution was added L (1.50 g, 8.6 mmol). Upon cooling to room temperature, a green precipitate formed which was collected by filtration, washed with diethyl ether, and air-dried. Yield: 1.50g (87%). Anal. Calcd for C ~ H ~ ~ N I C C, I ~ 33.2; T ~ : H, 6.5; N , 12.9; CI, 32.6. Found: C , 32.8; H, 6.6; N, 12.6; CI, 32.15. [LTiBr3] (2). A solution of TiBr4 (5.0 g, 13.6 mmol) in acetonitrile (40 mL) was heated to reflux under an argon atmosphere. The resulting dark red solution was cooled to 20 OC whereupon a red precipitate formed. To this mixtue was added dropwise a solution of L (2.5 g, 14.3 mmol) in CH3CN (10 mL) at ambient temperature. After stirring for 1 h, deoxygenated water (20 mL) was added which initiated the precipitation of a green microcrystalline solid which was collected by filtration, washed with deoxygenated CH3CN and diethyl ether, and dried in vacuo. The solid is stable in air and not hygroscopic. Yield: 2.2 g (35% with respect to TiBr4). Anal. Calcd for C9H21N3BrjTi: C, 23.5; H , 4.6; N, 9.1. Found: C, 23.7; H, 4.4; N, 8.9. [LTi(O$CF3)3] (3). To LTiC13 (1) (0.5 g, 1.5 mmol) under an argon atmosphere was added dropwise with efficient cooling (-5 "C) trifluoromethanesulfonicacid (3 mL). Agreensolution formedwithconcomitant generation of gaseous HCI. Addition of deoxygenated dry diethyl ether initiated the precipitation of a blue solid material which was collected by filtration under argon and washed with dry ether. The product is very hygroscopic and air-sensitive. Yield: 0.90 g (90%). Anal. Calcd for C I ~ H ~ I F ~ OC, ~S 21.6; ~ TH, ~ :3.2; N, 6.3. Found: C, 21.6; H , 3.2; N , 6.1. [LTi(NCS)3] (4). To a deoxygenated solution of NaSCN (1 .O g, 12.3 mmol) in methanol (15 mL) was added 3 (0.40 g, 0.60 mmol). After stirring for 30 min at 20 OC a blue microcrystalline solid precipitated which wascollected by filtration, washed with deoxygenateddiethyl ether, and dried in vacuo. The product is very moisture and air-sensitive. Yield: 0.16 g (67%). Anal. Calcd for C&I21N&Ti: C, 36.6; H, 5.4; N, 21.4. Found: C, 36.4; H , 5.3; N, 20.9. [LTiCI3Kl(S). AsolutionofTiC14(0.50g, 2.6mmol) indry acetonitrile (25 mL) was stirred at 20 OC for 30 min after which time L (0.80 g, 4.7 mmol) was added. Addition of dry diethyl ether (50 mL) to the brown solution initiated the precipitationof a pale yellow solid which wascollected by filtration, washed with dry diethyl ether, and air-dried. The product is stable in air and not particularly sensitive to moisture. Yield: 0.40 g (43%). Anal. Calcd for CgH21N3C14Ti: C, 29.95; H, 5.8; N , 11.6; CI, 39.2; Ti, 13.3. Found: C, 30.1; H , 6.1; N , 11.5; C1, 38.9; Ti, 13.5. [LTiC12(Na)HBPb](6). To a solution of NaN, (0.50 g, 8.0 mmol) in methanol (20 mL) was added 1 (0.30 g, 1 .O mmol). This mixture was heated to reflux for 10 min. After cooling to ambient temperature sodium tetraphenylborate (0.50 g) was added whereupon a colorless precipitate formed, which was collected by filtration, washed with cold diethyl ether, and air-dried. Yield: 0.30 g (45%). Anal. Calcd for C ~ ~ H ~ I N ~ B C I ~ T ~ : C, 60.8; H, 6.3; N , 12.9; Ti, 7.4. Found: C, 61.1; H, 6.0; N , 12.8; Ti, 7.2. [LTiO(NCS)z] (7). A solution of 4 (1.0 g, 2.5 mmol) in acetonitrile (40 mL) was heated to 55 OC in the presence of air until the purple color had disappeared and a yellow solution was obtained (ca. 1.5 h). This solution was allowed to stand in an open vessel for 48 h after which time a pale yellow microcrystalline solid formed (0.45 9). This material was recrystallized from an acetonitrile/water mixture (4: 1, 50 mL). Anal. Calcd for C12N21N5S20Ti: C , 37.6; H, 6.0; N, 19.9. Found: C, 37.4; H, 5.9; N, 19.8. [LTi(OCH3)Br2](C104) (8). A mixture of 2 (0.46 g, 1.0 mmol) in methanol (10 mL) and acetonitrile (10 mL) was heated to 60 OC in the presence of air until a clear yellow-orange solution was obtained. Addition of solid NaCl04 (0.20 g) initiated the precipitation of a yellow microcrystalline solid (0.20g, 39%) within 1 week. Singlecrystalssuitable for an X-ray structure determination were obtained by recrystallization from a 1: 1 methanol/acetonitrilemixture. IH N M R (80 MHz, CD3CN, 6, ppm): 2.95 (s, 6 H), two magnetically equivalent CH3 groups (C5 and C5a in Figure 13); 3.40 (s, 3 H), CH, group (Cl, Figure 13); 2.75-3.90 (m,12 H), methylene groups; 4.80 (s, 3 H), OCH3 group (C6, Figure 13). Anal. Calcd for C I ~ H ~ ~ N ~ B ~ ~C,C23.6; I O ~H,T 4.7; ~ : N, 8.3; C104, 19.4. Found: C, 23.8; H, 4.9; N, 8.3; clod, 19.3. [ L ~ T ~ z ( ~ O(9). ) C ~To ] an argon-purged solution of L (0.80 g, 4.6 mmol) in dimethylformamide (dmf) (25 mL) which contained ca. 2% water was added Tic13 (0.50 g, 3.2 mmol). The mixture was heated to reflux for 30 min under an argon atmosphere. Upon cooling to room temperature, a blue precipitate formed which was collected by filtration, washed three times with hot deoxygenated CH2Clzand diethyl ether, and air-dried. Yield: 0.45 g (24%). Anal. Calcd for C I ~ H ~ ~ N ~ OC,C I ~ T ~ ~ :
Ti 1,4,7-Trimethyl-1,4,7-triazacyclononane Complexes
Inorganic Chemistry, Vol. 31, No. 18, 1992 3139
Table 1. Crystallographic Data of Complexes blue 1 C9H21N3C13Ti 325.55 P&/c 12.356 (5) 7.348 (2) 15.897 (3)
chem formula fw space group a, A
b, A C,
A
a,deg
A deg
90.06 (2)
79 deg
v,A3
Z T,K radiation A, A ~ ~ g.cm-' ~ ~ p(Mo Ka), cm-1 transm coeff R O
RWb
c
d
1443 (1) 4 295 0.710 73 1.50 ~ 10.68 0,6334,723 0.050 0.057
green l a 7 8 13 C ~ H Z ~ N ~ C I ~ TC~I ~ H ~ I N S S ~ O T ~C ~ O H ~ ~ N ~ B ~ ~ C ICOI B ~H T~~N~O~F~PT~Z 351.35 509.5 672.36 P21/c Pna2 I Pnma Pi 12.430 (8) 7.076 (2) 12.819 (3) 7.676 (6) 7.337 (3) 14.247 (3) 11.608 (2) 7.695 (6) 15.929 (5) 16.163 (5) 12.686 (3) 13.67 (1) 75.05 (6) 90.19 (3) 79.67 (6) 70.03 (6) 1453 (2) 1629 (2) 1888 (1) 730(1) 4 4 4 1 295 295 295 295 0.710 73 0.071 73 0.710 73 0.710 73 1.49 1.43 1.793 1.53 10.61 7.7 48.1 6.8 0.6774.743 0.86-1 .OO 0.01 1 4 . 0 3 0 0.8354.953 0.043 0.050 0.061 0.080 0.046 0.047 0.056 0.082
36.0;H,6.9;N,13.8;C1,24.4;Ti,15.9. Found: C,36.2;H,7.1;N,14.0; CI, 24.0; Ti, 16.1. [~Ti2(p-O)Cl&1-2H20 (IO). Anargon-purged mixtureofTiC13 (0.50 g, 3.25 mmol) in dry dmf (25 mL) was heated toreflux for 2 h after which time L (0.80 g, 4.6 mmol) was added to the still hot solution. After heating to reflux for further 30 min water (0.50 mL) and air (=1 mL) were added. Upon cooling of the resulting solution to 0 OC, a blue precipitate formed which was collected by filtration and recrystallized from dichloromethane. Yield: 0.96 g (45%). Anal. Calcd for C18H4&03C15Ti2: C, 32.4; H, 6.8; N, 12.6; C1, 26.5; Ti, 14.3. Found: C, 32.2; H, 6.7; N, 12.5; CI, 27.0; Ti, 14.5. [L2Ti2(p-O)C4~1~2.5H20 (11). 10 (0.2 g, 0.2 mmol) was dissolved in acetonitrile (25 mL). The solution was stirred in the presence of air at 20 OC until a clear colorless solution was obtained. Removal of half of the reaction volume by rotary evaporation led to the crystallization of a colorless solid material which was collected by filtration, washed with diethyl ether, and air-dried. Yield: 0.10 g (50%). Anal. Calcd for C1&6N603.$16Ti2: C,30.4;H,6.5;N, ll.S;Ti, 13.5. Found: C,30.6; H, 6.3; N, 11.6; Ti, 13.8. [~Ti~(p-O)(OH)2(0)2)8H20(12). 1 (0.30g, 1.Ommol)wasdissolved in boiling water in the presence of air. After a clear colorless solution was obtained, the pH of the solution was adjusted to 7 by addition of NaHCO3. Slow cooling of thesolution to 20 OC resulted in the formation of colorless crystals. Yield: 0.01 g (15%). Anal. Calcd for C18H60N6013Ti2: C, 32.5; H, 9.1; N, 12.6. Found: C, 32.3; H, 8.9; N, 12.5. [L~Ti2(0)2(p-F)](PFs)(13). A solution of 1 (0.30 g, 1.0 mmol) and N a F (0.10 g, 2.3 mmol) in a mixture of nitromethane (25 mL) and water (5 mL) was heated to reflux for 30 min in the presence of air. To the then yellow solution sodium hexafluorophosphate (1 .O g) was added. A microcrystalline yellow solid precipitated which was recrystallized from a minimumamount of nitromethane. Yield: 0.30g (90%). Anal. Calcd for C1gH42N602F9PTi2: C, 32.3; H, 6.45; N, 12.4; F, 25.6; Ti, 14.2. Found: C, 31.9; H, 6.3; N, 12.5; F, 25.5; Ti, 14.4. Physical Measurements. Infrared spectra were recorded in the range 4000-400 cm-I as KBr disks on a Perkin-Elmer IT-IR spectrometer Model 1720 X;in the range 400-200 cm-I a Bruker I F S-85 spectrometer (CsI disks) was used. The Raman spectrum of a solid sample of 7 was recordedon a Perkin-Elmer FT-IR 1760 X model with additional Raman equipment FT-Raman 1700 X by using a Nd YAG laser (1064-nm, 0.4-W output). Electronic absorption spectra were recorded in the range 200-2000 nm on a Perkin-Elmer Lambda 9 spectrophotometer. Cyclic voltammetric measurements were carried out by the use of PAR equipment (potentiostat Model 173,universal programmer Model 175) on acetonitrile solutions that contained 0.1 M tetra-n-butylammonium hexafluorophosphate ([TBAIPFs) as the supporting electrolyte and 2 1 . 0 X M complex. El/?values, determined as (Ep,a EPJ/2, were referenced to the Ag/AgCI electrode (LiCl, C2HsOH) at ambient temperature and are uncorrected for junction potentials. Under our experimental conditions, the ferrocenium/ferrocene couple is at E112 = + O S 1 V vs Ag/ AgCI. Magnetic susceptibilities of powdered samples were measured by using the Faraday method in the temperature range 80-298 K. Corrections for diamagnetism wereapplied with use of Pascal's constants. IH NMR spectra were recordedon a Bruker WP 80 NMR spectrometer (80.13 MHz) andaBruker AM400NMRspectrometer (400.13 MHz).
+
Scheme I. Syntheses of Mononuclear Complexes
I
CH,OH NlSCN
I CH, TiBr,
+
CH CN
L A [ LTiBr,] -0r,
(2)
CYOH/CH,CN
0,
[ LTi(OCH,)Br,]' (8)
CH,CN
TiCI,+ L-ILTiCI,]CI (5)
The deuterated solvents were used as internal standards. The I9FNMR spectrum of 13 was recorded on a Bruker WP 89 spectrometer (54.13 MHz) with internal standard CFCI,. X-ray Crystallography. Crystal data, data collection, and refinement are summarized in Table I (and corresponding tables in the supplementary material). Graphite-monochromated Mo Ka X radiation was used throughout. Unit cell parameters were determined in all cases (1, la, 7,8, and 13) by the automatic indexing of 25-35 centered reflections. Intensity data were corrected for Lorentz, polarization, and absorption effects (empirical $-scans of seven reflections in the range 6 I 28 I 50°) in the usual manner. For 1 and l a numerical absorption corrections on the basis of 14 crystal faces, respectively were applied. The structures were solved by conventional Patterson and difference Fourier (1, la, 7) and direct methods (8,13) by using the SHELXTL-PLUSprogram package.23 The function minimized during full-matrix least-squares refinement was Xw(lFolwhere w = 1/ d ( F ) . Neutral-atom scattering factors and anomalous dispersion corrections for non-hydrogen atoms were taken from ref 24. The positions of the hydrogen atoms in 1 and l a were located in the difference Fourier map and were refined with variable positional parameters and fixed isotropic thermal parameters Uis0 (1, 0.04A2;l a , 0.06A2);thoseofallotherstructures wereplacedatcalculated positions with group isotropic thermal parameters (methylene H atoms) while the methyl groups were treated as rigid bodies. All non-hydrogen atoms were refined with anisotropic thermal parameters. Specificdetails of X-ray structure determinations are given below. 1 and la. When the refined atom coordinates of 1were used as starting set for the structure solution of la, an initial R value of only 0.20 was (23) Sheldrick, G. M. Full-matrix least-squaresstructurerefinement program package SHELXTL-PLUS, University of Gottingen. (24) International Tables of Crystallography; Kynoch: Birmingham, England, 1974; Vol. IV, pp 99, 149.
3740 Inorganic Chemistry, Vol. 31, No. 18, 1992 Table [I. Electronic Spectraa and Magnetic Properties of the ComDlexes magnetism,b complex ,,,A, nm (e, Lmol-l-cm-l) W'efilC(0 1.7 1 690 (30) 1.7 la 390,690 (30) 2 295 (4.1 X IO3), 720 (27) 1.7 1.7 3 nmc 1.6 4 nm diamagnetic 5 380 (350) diamagnetic 6 nm diamagnetic 7 230 (3.4 X IO4), 285 (sh), 306 (1.3 X IO4) 8 284 (5.8 X IO3), 381 (2.0 X lo3) diamagnetic 9 570 (520), 750 (sh), 940 (sh) 2.35 10 570 ( 2 5 5 ) , 750 (sh), 940 (sh) 1.70 diamagnetic 11 nm diamagnetic 12 nm diamagnetic 13 nm ~~~~~~~
Bodner et al.
~~
2oo
i
300
0
300
500
700
,-
..k
r
200
Measured in CH3CN solution at 20 OC. Temperature-independent magnetic moments measured in the temperature range 85 to 298 K.
