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Mono‐ and Hetero‐Dinuclear Complexes of Janus‐Head NHC Ligands Possessing Backbone Phosphinoyl Groups: the Case of Soft and Hard Metal Centers
Author(s) -
Majhi Paresh Kumar,
Serin Spencer C.,
Schnakenburg Gregor,
Gates Derek P.,
Streubel Rainer
Publication year - 2014
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/ejic.201402440
Subject(s) - chemistry , deprotonation , denticity , ligand (biochemistry) , metal , adduct , medicinal chemistry , carbon monoxide , stereochemistry , crystal structure , crystallography , catalysis , organic chemistry , receptor , ion , biochemistry
The synthesis and structures of Rh I and Ir I complexes bearing 4‐phosphinoyl‐ and 4,5‐bis(phosphinoyl)imidazol‐2‐ylidene ligands (NHC P ) is reported. Deprotonation of the corresponding imidazolium hydrogen sulfate salts by KO t Bu in the presence of [M(cod)Cl] 2 afforded complexes of the formula [M(cod)Cl(NHC P )] [ 5a/5b : NHC P = 4‐Ph 2 P(O)‐I i PrMe, 5a : M = Rh, 5b : M = Ir and 7a/7b : NHC P = 4,5‐{Ph 2 P(O)} 2 ‐I n BuMe]. The Rh I complexes 5a and 7a were then converted into [Rh(CO) 2 Cl(NHC P )] 8a and 9a via reaction with carbon monoxide; the average CO stretching frequencies [ 8a : $\tilde {\nu}$ (CO) av = 2036 cm –1 and 9a : $\tilde {\nu}$ (CO) av = 2038.4 cm –1 ] led to the conclusion that mono‐ and bis‐functionalized NHC P s act as relatively weaker donors than backbone unsubstituted NHC. A first examination of Janus‐head ligand properties of complex 7a revealed that reaction with TiCl 4 afforded hetero‐dinuclear 10a , a′ as a mixture of isomeric monodentate phosphinoyl titanium(IV) adducts. All products were characterized by elemental analyses, spectroscopic and spectrometric methods and, in addition, complexes 7a and 7b by single‐crystal X‐ray structure analysis.