TY - JOUR
T1 - Isolation of a bis(imino)pyridine molybdenum(i) iodide complex through controlled reduction and interconversion of its reaction products
AU - Pal, Raja
AU - Cherry, Brian R.
AU - Flores, Marco
AU - Groy, Thomas L.
AU - Trovitch, Ryan
PY - 2016
Y1 - 2016
N2 - Analysis of previously reported [(Ph2PPrPDI)MoI][I] by cyclic voltammetry revealed a reversible wave at -1.20 V vs. Fc+/0, corresponding to the Mo(ii)/Mo(i) redox couple. Reduction of [(Ph2PPrPDI)MoI][I] using stoichiometric K/naphthalene resulted in ligand deprotonation rather than reduction to yield a Mo(ii) monoiodide complex featuring a Mo-C bond to the α-position of one imine substituent, (κ6-P,N,N,N,C,P-Ph2PPrPDI)MoI. Successful isolation of the inner-sphere Mo(i) monoiodide complex, (Ph2PPrPDI)MoI, was achieved via reduction of [(Ph2PPrPDI)MoI][I] with equimolar Na/naphthalene. This complex was found to have a near octahedral coordination geometry by single crystal X-ray diffraction and electron paramagnetic resonance (EPR) spectroscopy revealed an unpaired Mo-based electron which is highly delocalized onto the PDI chelate core. Attempts to prepare a Mo(i) monohydride complex upon adding NaEt3BH to (Ph2PPrPDI)MoI resulted in disproportionation to yield an equimolar quantity of (κ6-P,N,N,N,C,P-Ph2PPrPDI)MoH and newly identified (Ph2PPrPDI)MoH2. Independent preparation of (Ph2PPrPDI)MoH2 was achieved by adding 2 equiv. NaEt3BH to [(Ph2PPrPDI)MoI][I] and a minimum hydride resonance T1 of 176 ms suggests that the Mo-bound H atoms are best described as classical hydrides. Interestingly, (Ph2PPrPDI)MoH2 can be converted to (κ6-P,N,N,N,C,P-Ph2PPrPDI)MoI upon iodomethane addition, while (Ph2PPrPDI)MoH2 is prepared from (κ6-P,N,N,N,C,P-Ph2PPrPDI)MoI in the presence of excess NaEt3BH. Similarly, (κ6-P,N,N,N,C,P-Ph2PPrPDI)MoI can be converted to (κ6-P,N,N,N,C,P-Ph2PPrPDI)MoH with 1 equiv. of NaEt3BH, while the opposite transformation occurs following iodomethane addition to (κ6-P,N,N,N,C,P-Ph2PPrPDI)MoH. Facile interconversion between [(Ph2PPrPDI)MoI][I], (κ6-P,N,N,N,C,P-Ph2PPrPDI)MoI, (κ6-P,N,N,N,C,P-Ph2PPrPDI)MoH, and (Ph2PPrPDI)MoH2 is expected to guide future reactivity studies on this unique set of compounds.
AB - Analysis of previously reported [(Ph2PPrPDI)MoI][I] by cyclic voltammetry revealed a reversible wave at -1.20 V vs. Fc+/0, corresponding to the Mo(ii)/Mo(i) redox couple. Reduction of [(Ph2PPrPDI)MoI][I] using stoichiometric K/naphthalene resulted in ligand deprotonation rather than reduction to yield a Mo(ii) monoiodide complex featuring a Mo-C bond to the α-position of one imine substituent, (κ6-P,N,N,N,C,P-Ph2PPrPDI)MoI. Successful isolation of the inner-sphere Mo(i) monoiodide complex, (Ph2PPrPDI)MoI, was achieved via reduction of [(Ph2PPrPDI)MoI][I] with equimolar Na/naphthalene. This complex was found to have a near octahedral coordination geometry by single crystal X-ray diffraction and electron paramagnetic resonance (EPR) spectroscopy revealed an unpaired Mo-based electron which is highly delocalized onto the PDI chelate core. Attempts to prepare a Mo(i) monohydride complex upon adding NaEt3BH to (Ph2PPrPDI)MoI resulted in disproportionation to yield an equimolar quantity of (κ6-P,N,N,N,C,P-Ph2PPrPDI)MoH and newly identified (Ph2PPrPDI)MoH2. Independent preparation of (Ph2PPrPDI)MoH2 was achieved by adding 2 equiv. NaEt3BH to [(Ph2PPrPDI)MoI][I] and a minimum hydride resonance T1 of 176 ms suggests that the Mo-bound H atoms are best described as classical hydrides. Interestingly, (Ph2PPrPDI)MoH2 can be converted to (κ6-P,N,N,N,C,P-Ph2PPrPDI)MoI upon iodomethane addition, while (Ph2PPrPDI)MoH2 is prepared from (κ6-P,N,N,N,C,P-Ph2PPrPDI)MoI in the presence of excess NaEt3BH. Similarly, (κ6-P,N,N,N,C,P-Ph2PPrPDI)MoI can be converted to (κ6-P,N,N,N,C,P-Ph2PPrPDI)MoH with 1 equiv. of NaEt3BH, while the opposite transformation occurs following iodomethane addition to (κ6-P,N,N,N,C,P-Ph2PPrPDI)MoH. Facile interconversion between [(Ph2PPrPDI)MoI][I], (κ6-P,N,N,N,C,P-Ph2PPrPDI)MoI, (κ6-P,N,N,N,C,P-Ph2PPrPDI)MoH, and (Ph2PPrPDI)MoH2 is expected to guide future reactivity studies on this unique set of compounds.
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U2 - 10.1039/c6dt00301j
DO - 10.1039/c6dt00301j
M3 - Article
AN - SCOPUS:84975078699
VL - 45
SP - 10024
EP - 10033
JO - Dalton Transactions
JF - Dalton Transactions
SN - 1477-9226
IS - 24
ER -