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A Tetraphosphane Imine Ligand Which Enforces Square‐Pyramidal Coordination
Author(s) -
Zimmermann Christopher,
Heinemann Frank W.,
Grohmann Andreas
Publication year - 2005
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.200500281
Subject(s) - chemistry , nickel , square pyramidal molecular geometry , ligand (biochemistry) , cobalt , crystallography , imine , steric effects , valence (chemistry) , counterion , reagent , coordination complex , ion , substituent , stereochemistry , protonation , coordination number , valence electron , crystal structure , inorganic chemistry , metal , electron , organic chemistry , catalysis , biochemistry , receptor , physics , quantum mechanics
The tetrapodal pentadentate NP 4 ligand 2,6‐C 5 H 3 N[CMe(CH 2 PPh 2 ) 2 ] 2 , which is readily prepared from the reaction of the corresponding tetrabromide with KPPh 2 , forms mononuclear complexes with nickel( II ) and cobalt( II ). In the case of nickel( II ), the coordination mode adopted by the ligand is sensitive to the nature of the counterion: Use of NiCl 2 gives a chloro complex as one of the products, which, as determined by X‐ray crystallography, has a central ion coordinated by three phosphane and one chloro substituent in a distorted square planar fashion; by contrast, the reaction with Ni(BF 4 ) 2 gives a complex of approximate square‐pyramidal geometry as the only product, in which all five atoms of the NP 4 set are coordinated to the nickel ion, despite the steric bulk of the eight phenyl substituents. The same type of complex is obtained with Co(BF 4 ) 2 and Co(ClO 4 ) 2 . Attempts to increase the coordination number of either complex beyond 5 have been unsuccessful. In particular, the cobalt( II ) complex (17 valence electrons) is practically inert to reagents such as O 2 , NO, NO + , I 2 , Cl 2 or H 2 . Full spectroscopic details for the complexes, as well as X‐ray structure analyses, are reported. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)