Alkali Metal Complexes of a tert-Butylphosphine-Bridged Biphenolate Ligand

作者：Hsu, Yu Lin; Liang, Lan Chang^*

来源：Organometallics, 2010, 29(23): 6201-6208.

DOI：10.1021/om100495e

The coordination chemistry of group 1 metals with a potentially tridentate, dianionic biphenolate phosphine ligand that carries a phosphorus-bound tert-butyl group is described. Deprotonation of bis(3,5-di-tert-butyl-2-hydroxyphenyl)-tert-butylphosphine (H-2[Bu-t-OPO]) with two equivalents of n-BuLi, NaH, or KH in ethereal solutions produces the corresponding alkali metal complexes {[Bu-t-OPO]M-2(solv)(x)}(2) (M = Li, Na, K; solv = DME, THF). An X-ray diffraction study of the lithium derivative reveals a dimeric structure that contains two [Bu-t-OPO]Li-2(DME) units linked by two dative O-Li bonds; the two lithium atoms in each monomeric [Bu-t-OPO]Li-2(DME) are bridged by both phenolate oxygen donors with only one lithium being coordinated to the phosphorus donor. As a result, the Li4O4 moiety in {[Bu-t-OPO]Li-2}(2) constitutes three successive Li2O2 tetragons fused in an open cubane structure. The coordination of the phosphorus donor to lithium in {[Bu-t-OPO]Li-2(DME)}(2) is also confirmed by variable-temperature P-31{H-1} and Li-7{H-1} NMR studies. Interestingly, the sodium complex is composed of two [Bu-t-OPO]Na-2(DME)(2) units linked by a bridging DME; each [Bu-t-OPO]Na-2(DME)(2) subunit is structurally similar to its lithium analogue though adopting one more coordinated DME. The potassium complex also contains two [Bu-t-OPO]K-2(THF)(2) moieties linked with two dative O-K bridges; the structure of the monomeric [Bu-t-OPO]K-2(THF)(2) unit, however, is markedly distinct from those of its lighter congeners. In addition to the anticipated fac-coordination from the heteroatoms in the biphenolate phosphine ligand, one of the potassium atoms in monomeric [Bu-t-OPO]K-2(THF)(2) is pi-bound to one of the aryl rings incorporated in the [Bu-t-OPO](2-) backbone.

• 出版日期2010-12-13
• 单位中山大学