Water-soluble Mo3S4 clusters bearing hydroxypropyl diphosphine ligands: synthesis, crystal structure, aqueous speciation, and kinetics of substitution reactions.
The [Mo(3)S(4)Cl(3)(dhprpe)(3)](+) (1(+)) cluster cation has been prepared by reaction between Mo(3)S(4)Cl(4)(PPh(3))(3) (solvent)(2) and the water-soluble 1,2-bis(bis(hydroxypropyl)phosphino)ethane (dhprpe, L) ligand. The crystal structure of [1](2)[Mo(6)Cl(14)] has been determined by X-ray diffraction methods and shows the typical incomplete cuboidal structure with a capping and three bridging sulfides. The octahedral coordination around each metal center is completed with a chlorine and two phosphorus atoms of the diphosphine ligand. Depending on the pH, the hydroxo group of the functionalized diphosphine can substitute the chloride ligands and coordinate to the cluster core to give new clusters with tridentate deprotonated dhprpe ligands of formula [Mo(3)S(4)(dhprpe-H)(3)](+) (2(+)). A detailed study based on stopped-flow, (31)P{(1)H} NMR, and electrospray ionization mass spectrometry techniques has been carried out to understand the behavior of acid-base equilibria and the kinetics of interconversion between the 1(+) and the 2(+) forms. Both conversion of 1(+) to 2(+) and its reverse process occur in a single kinetic step, so that reactions proceed at the three metal centers with statistically controlled kinetics. The values of the rate constants under different conditions are used to discuss on the mechanisms of opening and closing of the chelate rings with coordination or dissociation of chloride.
Departamento de Ciencia de los Materiales e Ingeniería Metalúrgica y Química Inorgánica, Facultad de Ciencias, Universidad de Cádiz, Apartado 40, Puerto Real, 11510 Cádiz, Spain. manuel.basallote@uca.es
Manuel G
MG
Basallote
M Jesús
MJ
Fernández-Trujillo
Jose Ángel
JÁ
Pino-Chamorro
Tomás F
TF
Beltrán
Carolina
C
Corao
Rosa
R
Llusar
Maxim
M
Sokolov
Cristian
C
Vicent
D056831:Coordination Complexes / Q000138:chemical synthesis* / Q000737:chemistry; D004220:Disulfides / Q000737:chemistry*; D007700:Kinetics; D008024:Ligands; D008958:Models, Molecular; D015394:Molecular Structure; D008982:Molybdenum / Q000737:chemistry*; D010720:Phosphines / Q000737:chemistry*; D012995:Solubility; D014867:Water / Q000737:chemistry*
D056831:Coordination Complexes; D004220:Disulfides; D008024:Ligands; D010720:Phosphines; D014867:Water; D008982:Molybdenum; C082964:molybdenum disulfide