New Alkali Metal Boratabenzenes: Structures of K([18]-Crown-6)(C5H5BMe), of the Tetrahydropyran Solvate K(3,5-Me2C5H3B−NMe2)(THP)2, and of Two THF Solvates of K[3,5-Me2C5H3B−N(SiMe3)2]

✍ Scribed by Xiaolai Zheng; Gerhard E. Herberich

• Publisher: John Wiley and Sons
• Year: 2003
• Tongue: English
• Weight: 195 KB
• Volume: 2003
• Category: Article
• ISSN: 1434-1948
• DOI: 10.1002/ejic.200300040

✦ Synopsis

Abstract

The potassium salt K(C~5~H~5~BMe) (8) can be obtained from 2‐(Me~3~Sn)C~5~H~5~BMe (7)/KO__t__Bu in toluene in essentially quantitative yield. Metalation of 1‐(dimethylamino)‐3‐methylene‐1,2,3,6‐tetrahydroborinine (9) with MN(SiMe~3~)~2~ (M = Na, K) in toluene afforded the unsolvated salts M(3,5‐Me~2~C~5~H~3~B−NMe~2~) (M = Na: 11; M = K: 12). Morpholino derivatives M(3,5‐Me~2~C~5~H~3~B−NC~4~H~8~O) (M = Li: 17; M = Na: 18) and the potassium salt K[3,5‐Me~2~C~5~H~3~B−N(SiMe~3~)~2~] (19) were obtained similarly. The unsolvated salts are highly air‐ and water‐sensitive, colorless powders. Crystallization with the help of auxiliary Lewis bases provided crystalline solvates K([18]‐crown‐6)(C~5~H~5~BMe) (20), K(THP)~2~(3,5‐Me~2~C~5~H~3~B−NMe~2~) (21), and the concomitant pseudopolymorphs K3,5‐Me~2~C~5~H~3~B−N(SiMe~3~)~2~~4/3~ (α‐22) and K3,5‐Me~2~C~5~H~3~B−N(SiMe~3~)~2~~3/2~ (β‐22), which were characterized structurally. The structures of α‐22 (space group __C__2/c) and β‐22 (space group 6~1~22) display novel chain forms, which have no precedents in boratabenzene and cyclopentadienide chemistry. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)