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Conformational Analysis of P,N‐Containing Eight‐Membered Heterocycles and Their Pt/Ni Complexes in Solution
Author(s) -
Latypov Shamil,
Strelnik Anna,
Balueva Anna,
Spiridonova Yulia,
Karasik Andrey,
Sinyashin Oleg
Publication year - 2016
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.201501331
Subject(s) - chemistry , intramolecular force , substituent , heteroatom , crystallography , metal , stereochemistry , ring (chemistry) , organic chemistry
In solution, 1,5‐diaza‐3,7‐diphosphacyclooctanes (P R 2 N R′ 2 ) are in equilibrium between the crown (CW; major) and chair–boat (CB; minor) forms. Aromatic substituent at the nitrogen atom shifts the equilibrium in favor of the CW form. [Pt(P R 2 N R′ 2 )]Cl 2 complexes exist in solution in the CB (CB*) conformation irrespective of the substituent at the heteroatoms. Aromatic substituents on N notably decrease the barrier of CB–CB* conformational exchange. Biligand complexes ([M(P R 2 N R′ 2 ) 2 ] 2+ , M = Pt, Ni) are in CBCB 1 conformation with distortion of the metal coordination plane. The CBCB 1 form is in degenerate exchange with the CBCB 1 * form. In general, distortion of the metal coordination plane and the intramolecular exchange barriers are higher in Ni complexes than in Pt ones. An Ar group at the nitrogen atom increases the heterocycle interconversion rate. Bulky P ‐substituents increase the distortion of the metal coordination plane and slow down its “twisting” rate. Counterions with stronger coordinating ability increase the barriers of intramolecular conversion.