TY - JOUR
T1 - A novel and simple route for bromide replacement in pyrazolyl-pyridazine ReI tricarbonyl complexes leads to a zwitterion stabilized by hydrogen bonding
AU - Saldías, Marianela
AU - Mella, Pablo
AU - Pizarro, Nancy
AU - Vega, Andrés
N1 - Funding Information:
The authors gratefully acknowledge partial financial support of Comisión Nacional de Investigación Científica y Tecnológica , grants FONDECYT 1160546 , 1160749 , 3170100 , ACT-1404 and Financiamiento Basal para Centros Científicos y Tecnológicos de Excelencia FB0807.
PY - 2020/1
Y1 - 2020/1
N2 - The reaction of 3-pyrazolyl-pyridazine-6-carboxylic (LCOOH) and 3-3,5-dimethylpyrazolyl-pyridazine-6-carboxylic (Me2LCOOH) acids with bromotricarbonyl-tetrahydrofuran-rhenium(I) dimer in DMF solution followed by water addition, leads simple and cleanly to the rhenium(I) de-halided fac-aquo-tricarbonyl-complexes [(LCOO)(H2O)Re(CO)3] and [(Me2LCOO)(H2O)Re(CO)3] respectively, without the requirement of using a silver salt. It was possible to isolate each compound with the pyrazolyl-pyridazine carboxylate ligand showing the chelating N,O-mode ([(N,O-LCOO)(H2O)Re(CO)3] and [(N,O-Me2LCOO)(H2O)Re(CO)3]). For the [(Me2LCOO)(H2O)Re(CO)3] compound, it was also possible to isolate the ligand as a chelating diimine ([(N,N-Me2LCOO)(H2O)Re(CO)3]). This last coordination mode leads to a zwitterionic but neutral molecule, with a naked carboxylate as negative extreme and the metal with positive charge in the other side. The negative formal charge in the carboxylate is stabilized within the crystal structure of [(N,N-Me2LCOO)(H2O)Re(CO)3] through hydrogen bonds to water molecules from neighboring molecules dimers, with donor acceptor distances (D···A) of 2.566(10)Å and 2.645(6)Å. DFT optimization of the zwitterion in the gas phase suggests that its geometry would twist to allow the formation of an intramolecular hydrogen bond between carboxylate and the coordinated water molecule. This shows the key stabilizing effect of the hydrogen bond for the negative charge of the carboxylate into the zwitterion crystal structure.
AB - The reaction of 3-pyrazolyl-pyridazine-6-carboxylic (LCOOH) and 3-3,5-dimethylpyrazolyl-pyridazine-6-carboxylic (Me2LCOOH) acids with bromotricarbonyl-tetrahydrofuran-rhenium(I) dimer in DMF solution followed by water addition, leads simple and cleanly to the rhenium(I) de-halided fac-aquo-tricarbonyl-complexes [(LCOO)(H2O)Re(CO)3] and [(Me2LCOO)(H2O)Re(CO)3] respectively, without the requirement of using a silver salt. It was possible to isolate each compound with the pyrazolyl-pyridazine carboxylate ligand showing the chelating N,O-mode ([(N,O-LCOO)(H2O)Re(CO)3] and [(N,O-Me2LCOO)(H2O)Re(CO)3]). For the [(Me2LCOO)(H2O)Re(CO)3] compound, it was also possible to isolate the ligand as a chelating diimine ([(N,N-Me2LCOO)(H2O)Re(CO)3]). This last coordination mode leads to a zwitterionic but neutral molecule, with a naked carboxylate as negative extreme and the metal with positive charge in the other side. The negative formal charge in the carboxylate is stabilized within the crystal structure of [(N,N-Me2LCOO)(H2O)Re(CO)3] through hydrogen bonds to water molecules from neighboring molecules dimers, with donor acceptor distances (D···A) of 2.566(10)Å and 2.645(6)Å. DFT optimization of the zwitterion in the gas phase suggests that its geometry would twist to allow the formation of an intramolecular hydrogen bond between carboxylate and the coordinated water molecule. This shows the key stabilizing effect of the hydrogen bond for the negative charge of the carboxylate into the zwitterion crystal structure.
UR - http://www.scopus.com/inward/record.url?scp=85075540460&partnerID=8YFLogxK
U2 - 10.1016/j.inoche.2019.107621
DO - 10.1016/j.inoche.2019.107621
M3 - Article
AN - SCOPUS:85075540460
SN - 1387-7003
VL - 111
JO - Inorganic Chemistry Communications
JF - Inorganic Chemistry Communications
M1 - 107621
ER -