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1、 Supplementary Data to Synthesis and Characterization of Synthetically Useful Salts of the Weakly-Coordinating Dianion B12Cl122- Vanessa Geis,a Kristin Guttsche,a Carsten Knapp,*a Harald Scherer,a Rabiya Uzuna a Institut fr Anorganische und Analytische Chemie, Albert-Ludwigs Universitt Freiburg, Alb
2、ertstr. 21, 79104 Freiburg i. Br., Germany. E-mail: carsten.knappac.uni-freiburg.de; Fax: +49-761-203-6001; Tel: +49-761-203-6150. S1 1. Syntheses 1.1. Synthesis of NEt3H2B12H12. 1.1.1. A full experimental account. NaBH4 (97.91 g, 2.599 mol) in diglyme (400 ml) was charged into a 1000 mL three-necke
3、d round bottom flask equipped with a 250 mL dropping funnel, which should reach under the surface of the reaction mixture, with a pressure equalizing sidearm, a reflux condenser and a bubbler containing silicon oil. Iodine (205.58 g, 0.810 mol) was dissolved in a minimal amount of diglyme (350 mL)a
4、and added to the dropping funnel. The entire apparatus was flushed with dry argon. The suspension of NaBH4 in diglyme was vigorously stirred and heated until the temperature rose to 100 C.b Then iodine was added drop-wise over a period of 6 h.c,d During the addition the amount of insoluble NaBH4 dec
5、reased and at the end a yellow color of the reaction mixture was observed. The dropping funnel was disassembled and the reaction mixture was continuously stirred over night at 100 C under an atmosphere of argon to complete the formation of B3H8-. On the next day the temperature was increased and the
6、 reaction mixture was refluxed (temperature of the oil bath was 185 oC) over night (16 h) under an atmosphere of dry argon to completely disproportionate B3H8- to B12H122- and BH4- (at this stage, usually, the yellow color disappeared and a white precipitate started to form). Eventually the reaction
7、 mixture was cooled down and the diglyme was distilled off under dynamic vacuum starting at 90 C (oil bath) and increased to 140 C after 1 hour.e A large amount of white solid (Na2B12H12, NaBH4, NaI) remained.f The white solid was dissolved in 600 mL of water (cloudy solution) and 280 mL of concentr
8、ated hydrochloric acid were added carefully to the a Iodine dissolves very slowly in diglyme. However, vigorous stirring of the suspension for several hours (over night) dissolves the iodine completely. b At temperatures higher 100 C B 3H8- decomposes and boron clusters start to form. c A faster add
9、ition of iodine leads to reduced yields. d During the addition of iodine hydrogen is formed, which escapes (together with some diborane) through the bubbler. The reaction should be carried out in a well vented fume hood. e To reduce the costs the diglyme can be recycled by drying over CaH 2 followed
10、 by distillation. f Previously it has been recommended to wash the solid reaction mixture with petrol ether to remove last traces of diglyme.9 We did not find this additional step helpful. S2 solution (caution: hydrogen evolution). The acidified clear solution was stored in a fridge (+6 C) over nigh
11、t and colorless crystals (ca. 15 g) of boric acid (Raman,111B NMR) were formed and removed by filtration.9 The filtrate was treated with 400 mL Et3N (pH = 9-10) and readily a voluminous white solid precipitated.g The cloudy solution was stirred over night (14 h) to complete the precipitation.h The w
12、hite solid (ca. 80 g) was collected by filtration. According to 11B NMR the white solid still contained large amounts of boric acid.i Therefore the solid was suspended in water, heated, and then filtrated while still hot (50 and 60 C) to remove the more soluble boric acid. The product was dried in v
13、acuum to give NEt3H2B12H12 (28.50 g, 0.082 mol, 51%) as a white solid. NEt3H2B12H12 prepared according to this method was of high purity and did not contain any remaining boric acid or smaller boron clusters (e.g. B6H62-, B10H102-). 1.1.2. Discussion The reaction proceeds in two steps. B3H8- is prep
14、ared in situ in the first step from NaBH4 and I2 and thermally decomposed in the second step to give B12H122- as the main product. a) Synthesis of intermediary B3H8-. Numerous accounts on the reaction of BH4- and I2 have been published. Depending on the stoichiometry and reaction conditions differen
15、t products are observed.2 A small excess of I2 causes further oxidation of the B3H8-,3 while a larger excess of I2 (I2 : BH4- 2) results in the complete formation of BI3.4 A slight excess of BH4- gives B2H6 as the main product.5 A ratio of BH4- : I2 3:1 yields B3H8- as the only product (Eq. 1).6 3 N
16、aBH4 + I2 NaB3H8 + 2 NaI + 2 H2 (Eq. 1) g Some authors suggested the addition of NEt 3HCl to complete the precipitation of the product. We found this unnecessary. h During stirring several colours appeared (white, pink, yellow). i Note: 11B NMR samples should be measured in D 2O to detect the boric acid. S3 Reactions optimized for the synthesis of B3H8- use a large excess of BH4- (up to 1:6) to avoid any fur
