Premium
Functionalized Ether Derivatives of HOCH 2 C(CH 2 PPh 2 ) 3 and Related Tripod Ligands – Synthesis and Coordination Chemistry
Author(s) -
Schober Peter,
Soltek Rainer,
Huttner Gottfried,
Zsolnai Laszlo,
Heinze Katja
Publication year - 1998
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/(sici)1099-0682(199810)1998:10<1407::aid-ejic1407>3.0.co;2-j
Subject(s) - chemistry , deprotonation , electrophile , neopentane , ether , trifluoromethanesulfonate , pyridine , steric effects , medicinal chemistry , coordination complex , stereochemistry , metal , organic chemistry , molecule , catalysis , ion
Neopentane‐derived tripod ligands of the general type HOCH 2 C(CH 2 PPh 2 )(CH 2 Y)(CH 2 Z) ( 1 ; Y, Z = PPh 2 , SR) are notoriously resistant to ether formation at their hydroxy group. Two routes have been found, which allow the transformation of 1 into ether functionalized tripod ligands ROCH 2 C(CH 2 PPh 2 )(CH 2 Y)(CH 2 Z) (Y = Z = PPh 2 : 5 , Y = Z = SR: 8 ). One of these strategies relies upon the η 3 coordination of 1 in 1· Mo(CO) 3 ( 2 ). By this way the donor groups are efficiently protected and the steric encumbrance of the CH 2 OH group at the backbone of the ligands is greatly reduced by fixing three arms of the neopentane scaffolding to the metal center. After deprotonation, reaction with electrophiles will produce the corresponding ether derivatives ROCH 2 C(CH 2 PPh 2 )(CH 2 Z) 2 ( 3 ). Mesylation of 2 leads to MeSO 2 OCH 2 C(CH 2 PPh 2 )3 · Mo(CO) 3 ( 4 ), which reacts with alkoxides to produce 3 in a sequence of reversed polarity. Ligands 5 [ROCH 2 C(CH 2 PPh 2 ) 3 ] are liberated from 3 by UV irridation of their solutions in the presence of pyridine N ‐oxide. Direct etherification of 1 is also possible in some cases after deprotonation of 1 by KO t Bu and subsequent reaction with an electrophile RX in the narrow temperature range between –10 and +20 °C. By this way, ω‐methyl polyglycol ether functions are easily introduced resulting in H 3 C(OC 2 H 4 ) n OCH 2 C(CH 2 PPh 2 ) 3 ( 5g , h ).