Paper
Dalton Transactions
NaCl plates, or on solids protected with a thin layer of nujol temperature, then slowly warmed to room temperature and
using an Agilent Cary 630 ATR FTIR spectrometer. The solid stirred overnight. An off-white crystalline precipitate of 5 had
state mass spectrum was recorded using an Agilent 5975C formed which was filtered off. Concentration of the yellow-
inert MSD with triple-axis detector and SIS direct insertion brown filtrate to ca. 10 mL and cooling to 4 °C afforded a
probe. Melting points were determined in sealed glass capil- second crop of colourless crystals of 5, further concentration
laries under dinitrogen and are uncorrected. Elemental ana- to ca. 4 mL and cooling to 4 °C afforded a small third crop.
lyses were performed by the Elemental Analysis Service at Obtained crops were washed with a small amount of n-hexane
London Metropolitan University. [(LLi)4(LiH)4] 1 and [LLi] 29 (ca. 3–4 mL) and dried under vacuum. Yield: 0.42
g
were prepared according to literature procedures. All other (0.382 mmol, 58%); mp: decomposition, above ca. 210 °C
reagents were used as received (Aldrich Chemical Company). gradually more yellow, then brown; fully decomposed at
1
Abbreviations: br = broad, vbr = very broad, m = multiplet. around 240 °C; H NMR (C6D6, 300.1 MHz, 303 K): δ 0.25 (vbr,
NMR scale reactions were typically carried out on ca. 20 mg 12H, CH(CH3)2), 0.90 (vbr, 12H, CH(CH3)2), 3.47 (br, 4H,
samples in 5 mm NMR tubes with J. Young stopcock in dried CH(CH3)2), 6.47–7.33 (m, 38H, Ar-H), 7.67–7.83 (br, 8H, Ar-H);
1
deuterated benzene (ca. 0.55 mL), followed by H and 31P{1H} 1H NMR (C6D6, 300.1 MHz, 333 K): δ 0.70 (br, 24H, CH(CH3)2),
NMR spectroscopy, and are described in the main text. 1H and 3.44 (sept, JH–H ≈ 6.8 Hz, 4H, CH(CH3)2), 6.54 (t, br, JH–H ≈ 7.2
31P{1H} NMR spectra of reactions of [(LLi)4(LiH)4] 1, and [LLi] Hz, 4H, Ar-H), 6.72 (t, vbr, 4H, Ar-H), 6.82–7.31 (m, 30H, Ar-H),
2, with DCC and PhNvNPh, respectively, are given in the ESI.† 7.74 (dd, br, JH–H ≈ 10.8, 7.8 Hz, 8H, Ar-H); 7Li NMR (C6D6,
155.5 MHz, 303 K): δ 3.3 (br); 13C{1H} NMR (C6D6, 75.5 MHz,
Spectroscopic data for [LLi(THF)3]
333 K): δ 24.4 (vbr, CH(CH3)), 28.5 (CH(CH3)2), 112.8 (br, Ar-C),
The title compound was obtained by recrystallization of a [LLi] 114.9 (Ar-C), 119.8 (d, not well resolved, Ar-C), 121.3 (Ar-C),
containing sample from THF. The spectroscopic data are 122.8 (d, JC–P = 3.5 Hz, Ar-C), 123.9 (d, JC–P = 2.4 Hz, Ar-C),
similar to that previously reported for [LLi(THF)2].9 Yellow 128.3 (Ar-C), 128.7 (Ar-C), 130.0 (Ar-C), 131.3 (br, Ar-C), 133.0
1
crystals; mp: 97–100 °C; H NMR (C6D6, 400.1 MHz, 303 K): δ (m, br, overlapping Ar-C), 141.3 (Ar-C), 145.3 (d, JC–P = 6.3 Hz,
1.22 (mc, 12H, THF-OCH2CH2), 1.31 (d, JH–H = 6.8 Hz, 12H, Ar-C), 147.2 (d, JC–P = 19.2 Hz, Ar-C), 160.9 (Ar-C); 31P{1H} NMR
CH(CH3)2), 3.18 (mc, 12H, THF-OCH2CH2), 4.16 (sept, br, JH–H (C6D6, 162.0, 303 K): δ 19.7 (vbr), 22.5 (vbr); 31P{1H} NMR
≈ 6.8 Hz, 2H, CH(CH3)2), 6.95–7.29 (m, 9H, Ar-H), 7.75–7.85 (C6D6, 121.5 333 K): δ 21.0 (br); IR (nujol), ˜ν/cm−1: 1594m,
˜
7
(m, 4H, Ar-H); Li NMR (C6D6, 155.5 MHz, 303 K): δ 0.77 (s); 1479m, 1460s, 1437s, 1376s, 1332m, 1298m, 1280m, 1228s,
13C{1H} NMR (C6D6, 100.6 MHz, 303 K):
δ 24.4–24.5 1214m, 1111m, 1052m, 1027s, 944m, 812m, 778m, 750s,
(CH(CH3)2, THF-OCH2CH2), 28.0 (d, JC–P = 4.8 Hz, CH(CH3)2), 721m, 690m; elemental analysis (%) for C72H74Li2N6P2
68.2 (THF-OCH2CH2), 118.7 (d, not well resolved, Ar-C), 123.5 (1099.23 g mol−1): calcd: C 78.67, H 6.79, N 7.65; found: C
(d, JC–P = 1.7 Hz, Ar-C), 126.6 (Ar-C), 127.9 (d, JC–P = 4.5 Hz, Ar- 78.63, H 6.68, N 7.55.
C), 131.6 (d, JC–P = 18.8 Hz, Ar-C), 144.6 (d, JC–P = 5.4 Hz, Ar-C),
152.9 (d, br, JC–P ≈ 30 Hz, Ar-C), 156.2 (d, JC–P ≈ 19 Hz, Ar-C);
Spectroscopic data for [LN(Ph)N(Ph)Li(THF)] 6
31P{1H} NMR (C6D6, 162.0, 303 K): δ 60.5 (br); IR (nujol), Colourless crystals of the title compound were obtained by
˜ν/cm−1: 1583m, 1460s, 1432m, 1417m, 1375m, 1366m, 1307s, recrystallizing a sample of 5 from hexane–THF. 1H NMR (C6D6,
1253m, 1231s, 1185s, 1102m, 1075m, 1045s, 911s, 822m, 778s, 300.1 MHz, 303 K): δ 0.85 (vbr, 6H, CH(CH3)2), 1.14 (vbr, 6H,
737s, 699s, 680m, 574 m.
CH(CH3)2), 1.18 (mc, 4H, THF-OCH2CH2), 3.36 (mc, 4H,
THF-OCH2CH2), 3.64 (sept, br, 2H, CH(CH3)2), 6.49–7.82 (m,
21H, Ar-H), 8.31 (vbr, 2H, Ar-H); 1H NMR (C6D6, 300.1 MHz,
[(LSiMe2OLi)2(HDCCLi)2] 3·3C6H6 and [(HDCC)6Li8O] 413
The reaction of [(LLi)4(LiH)4] 1 with DCC at room temperature 343 K):
δ 0.96 (br, 12H, CH(CH3)2), 1.33 (mc, 4H,
led to oily product mixtures that could not be separated. 1H THF-OCH2CH2), 3.47 (mc, 4H, THF-OCH2CH2), 3.65 (sept,
and 31P{1H} NMR spectra for the in situ reaction can be found JH–H = 6.8 Hz, 2H, CH(CH3)2), 6.43–8.10 (m, 23H, Ar-H); 7Li
in the ESI (Fig. S1 and S2†) plus those of the related reaction NMR (C6D6, 155.5 MHz, 303 K): δ 2.6 (m); 13C{1H} NMR (C6D6,
of [LLi] 2 with DCC (Fig. S3–5†). Separation attempts did lead 75.5 MHz, 343 K): δ 24.1 (CH(CH3)), 25.4 (THF-OCH2CH2), 28.3
to small amounts of crystals of the title compounds that were (CH(CH3)2), 68.6 (THF-OCH2CH2), 112.1 (br, Ar-C), 112.7 (br,
structurally characterised only after incorporation of silicone Ar-C), 121.5–122.3 (m, overlapping resonances, Ar-C), 123.6
grease (3) or traces of air or moisture (4); further details are (Ar-C), 128.1 (partially hidden by solvent resonances, Ar-C),
described in the main text.
129.0 (Ar-C), 131.2 (d, JC–P = 2.2 Hz, Ar-C), 133.2 (d, JC–P =
8.8 Hz, Ar-C), 144.0–144.4 (m, overlapping resonances, Ar-C),
146.7 (d, JC–P = 10.1 Hz, Ar-C), 160.0 (br, Ar-C); 31P{1H} NMR
[{LN(Ph)N(Ph)Li}2] 5
The title compound was formed and isolated from reactions (C6D6, 162.0, 303 K): δ 10.3 (br).
involving [(LLi)4(LiH)4] 1, and [LLi] with azobenzene,
respectively, see main text. For a preparative scale:
2
[{PhN(Li)-N(Li)Ph}4] 7·6C6H6
Azobenzene (0.245 g, 1.346 mmol, 1.03 eq.) was added to a Yellow, rod to needle-like crystals of the title compound were
cooled (−80 °C) fine slurry of [LLi] 2 (0.48 g, 1.306 mmol) in obtained from the reaction of LiH complex 1 with PhNNPh,
toluene (20 mL). The reaction was stirred briefly at this alongside [{LN(Ph)N(Ph)Li}2] 5, see main text.
7084 | Dalton Trans., 2014, 43, 7078–7086
This journal is © The Royal Society of Chemistry 2014