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Synthesis, Structures, and Stability of N‐Donor‐Stabilized N‐Silylphosphoranimine Cations
Author(s) -
Huynh Keith,
Rivard Eric,
Lough Alan J.,
Manners Ian
Publication year - 2007
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.200601452
Subject(s) - chemistry , counterion , silver salts , substituent , halide , yield (engineering) , medicinal chemistry , nitrogen , polar effect , ion , inorganic chemistry , organic chemistry , materials science , metallurgy
A series of DMAP‐stabilized (DMAP=4‐dimethylaminopyridine) N‐silylphosphoranimine cations [DMAP ⋅ PR 2 NSiMe 3 ] + , bearing R=Cl ([ 8 ] + ), Me ([ 10 a ] + ), Me/Ph ([ 10 b ] + ), Ph ([ 10 c ] + ), and OCH 2 CF 3 ([ 10 d ] + ) substituents, have been synthesized from the reactions of the parent phosphoranimines Cl 3 PNSiMe 3 ( 3 ) and XR 2 PNSiMe 3 (X=Cl ( 9 ), Br ( 11 ); R=Me ( 9 a and 11 a ), Me/Ph ( 9 b and 11 b ), Ph ( 9 c and 11 c ), and OCH 2 CF 3 ( 9 d and 11 d )) with DMAP and silver salts as halide abstractors. Reactions in the absence of silver salts yield the corresponding cations, with halide counterions. The stability of the salts is highly dependent on the phosphoranimine substituent and the nature of the counteranion, such that electron‐withdrawing substituents and non‐coordinating anions yield the most stable salts. X‐ray structural determination of the cations reveal extremely short phosphoranimine PN bond lengths for the cations [ 8 ] + and [ 10 d ] + (1.47–1.49 Å) in which electron‐withdrawing substituents are present and a longer phosphoranimine PN length for the cation [ 10 a ] + (1.53 Å) in which electron‐donating substituents are present. Very wide bond angles at nitrogen are observed for the salts containing the cation [ 10 d ] + (158–166°) and indicate significant sp hybridization at the nitrogen centre.