PGSE and NOE NMR evidence for higher order aggregation in some cationic ruthenium complexes in both protic and aprotic solvents.
PGSE and NOE NMR measurements were carried out for complexes [Ru(eta(6)-cymene)((2-R-C(6)H(4))N=C(Me)-C(Me)=N(2-R-C(6)H(4)))Cl]X (X = BF(4) or BPh(4)) in both protic and aprotic solvents with a relative permettivity (epsilon(r)) ranging from 2.27 (benzene-d(6)) to 46.45 (dimethyl sulfoxide-d(6)). PGSE and NOE results indicate that complexes have a tendency to aggregate even in medium-polarity solvents such as ethanol (epsilon(r) = 24.55) and methanol (epsilon(r) = 32.66). In addition, the aggregation process is favored by a decrease of epsilon(r) and, unexpectedly, by protic solvents. NOE measurement investigations, interpreted with the help of theoretical calculations and confirmed by X-ray single crystal studies, suggest different aggregation processes for the two counteranions: two cationic moieties approach each other when X = BF(4) while the anion bridges two cationic moieties when X = BPh(4).
Zuccaccia
Daniele
D
Dipartimento di Chimica, Università degli Studi di Perugia, Via Elce di Sotto 8, 06123 Perugia, Italy.
Sabatini
Stefano
S
Bellachioma
Gianfranco
G
Cardaci
Giuseppe
G
Clot
Eric
E
Macchioni
Alceo
A