TY - JOUR

T1 - N-heterocyclic carbenes in Lewis acid/base stabilised phosphanylboranes

AU - Adolf, Ariane

AU - Vogel, Ulf

AU - Zabel, Manfred

AU - Timoshkin, Alexey Y.

AU - Scheer, Manfred

PY - 2008/8

Y1 - 2008/8

N2 - The reactions of 2-borane-1,3,4,5-tetramethylimidazoline (BH 3·NHCMe) with selected phosphane adducts of the Lewis acids B(C6F5)3 and Ga(C6F 5)3 are studied. Among others, adducts (C 6F5)3Ga·PH2Cp* (1a) and (C6F5)3B·PH2Cp* (2) are used as starting materials. When the (C6F5) 3Ga-phosphane adducts 1a and (C6F5) 3Ga·PPhH2 are treated with BH3· NHCMe, the Lewis acid/base stabilised phosphanylboranes (C 6F5)3Ga·P(Cp*)HBH 2·NHCMe (3a) and (C6F5) 3Ga· P(Ph)HBH2·NHCMe (3b) are formed, respectively, by a hydrogen elimination reaction. In contrast, the reaction of BH3·NHCMe with the (C6F 5)3B-phosphane adducts (C6F5) 3B· PH2R [R = H, R = Cp* (2) and R = Ph] in CH2Cl2 at room temperature leads to the formation of a salt with the general formula [(C6F5)3BH] [RPH2·BH2·NHCMe] (4a: R = H, 4b: R = Cp*, 4c: R = Ph). To synthesise the Lewis acid/base stabilised phosphanylborane with (C6F5)3B as a Lewis acid and 1,3,4,5-tetramethylimidazolylidene (NHCMe) as a Lewis base, a different synthetic pathway was applied: the replacement reaction of the Lewis base. At room temperature, NHCMe displaced the amine in (C 6F5)3B·P(Ph)HBH2· NMe3 to yield (C6F5)3B·P(Ph) HBH2·NHCMe (5). All compounds were comprehensively characterised by spectroscopic methods. Compounds 1a, 1b, 2, 3a, 3b and 5 were additionally characterised by X-ray crystallographic analysis.

AB - The reactions of 2-borane-1,3,4,5-tetramethylimidazoline (BH 3·NHCMe) with selected phosphane adducts of the Lewis acids B(C6F5)3 and Ga(C6F 5)3 are studied. Among others, adducts (C 6F5)3Ga·PH2Cp* (1a) and (C6F5)3B·PH2Cp* (2) are used as starting materials. When the (C6F5) 3Ga-phosphane adducts 1a and (C6F5) 3Ga·PPhH2 are treated with BH3· NHCMe, the Lewis acid/base stabilised phosphanylboranes (C 6F5)3Ga·P(Cp*)HBH 2·NHCMe (3a) and (C6F5) 3Ga· P(Ph)HBH2·NHCMe (3b) are formed, respectively, by a hydrogen elimination reaction. In contrast, the reaction of BH3·NHCMe with the (C6F 5)3B-phosphane adducts (C6F5) 3B· PH2R [R = H, R = Cp* (2) and R = Ph] in CH2Cl2 at room temperature leads to the formation of a salt with the general formula [(C6F5)3BH] [RPH2·BH2·NHCMe] (4a: R = H, 4b: R = Cp*, 4c: R = Ph). To synthesise the Lewis acid/base stabilised phosphanylborane with (C6F5)3B as a Lewis acid and 1,3,4,5-tetramethylimidazolylidene (NHCMe) as a Lewis base, a different synthetic pathway was applied: the replacement reaction of the Lewis base. At room temperature, NHCMe displaced the amine in (C 6F5)3B·P(Ph)HBH2· NMe3 to yield (C6F5)3B·P(Ph) HBH2·NHCMe (5). All compounds were comprehensively characterised by spectroscopic methods. Compounds 1a, 1b, 2, 3a, 3b and 5 were additionally characterised by X-ray crystallographic analysis.

KW - Boron

KW - Carbenes

KW - Gallium

KW - Lewis acids

KW - Lewis bases

KW - Phosphorus

UR - http://www.scopus.com/inward/record.url?scp=53249124889&partnerID=8YFLogxK

U2 - 10.1002/ejic.200800305

DO - 10.1002/ejic.200800305

M3 - Article

AN - SCOPUS:53249124889

SP - 3482

EP - 3492

JO - Berichte der deutschen chemischen Gesellschaft

JF - Berichte der deutschen chemischen Gesellschaft

SN - 0365-9496

IS - 22

ER -