How to make a major shift in a Redox potential: Ligand control of the oxidation state of dimolybdenum units

F. Albert Cotton; Lee M. Daniels; Chun Y. Liu; Carlos A. Murillo; Arthur J. Schultz; Xiaoping Wang

doi:10.1021/ic025632w

How to make a major shift in a Redox potential: Ligand control of the oxidation state of dimolybdenum units

F. Albert Cotton, Lee M. Daniels, Chun Y. Liu, Carlos A. Murillo, Arthur J. Schultz, Xiaoping Wang

Research output: Contribution to journal › Article › peer-review

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Abstract

A compound reported earlier (Polyhedron 1989, 8, 2339) as (Buⁿ₄N)₂H₂{Mo₂ [Mo(CO)₄(PhPO₂)₂]₂} has been reexamined. We find that the hydrogen atoms in this formula are not present. Therefore, the complex must be considered as having a central triply bonded Mo₂⁶⁺ unit, instead of a quadruply bonded Mo₂⁴⁺ unit. Our conclusion is based on a variety of experimental evidence, including X-ray crystal structures of four crystal forms, as well as the neutron crystal structure of one. This explains the relatively long Mo-Mo bond lengths found in the range 2.1874(7)-2.2225(7) Å and the absence of a δ → δ* transition in the visible spectrum. From electrochemistry we also find that the diphosphonate ligand has such an exceptional ability to stabilize higher oxidation states that even common solvents such as CH₂CI₂ and C₂H₂OH readily oxidize the Mo₂⁴⁺ unit that is introduced from the Mo₂(O₂-CCH₃)₄ or [Mo₂(O₂CCH₃)₂ (NCCH₃)₆](BF₄)₂ employed in the preparation. The only chemically reversible wave at E_1/2 = -1.54 V vs Ag/AgCl corresponds to the reduction process Mo₂⁶⁺ → Mo₂⁵⁺.

Original language	English
Pages (from-to)	4232-4238
Number of pages	7
Journal	Inorganic Chemistry
Volume	41
Issue number	16
DOIs	https://doi.org/10.1021/ic025632w
State	Published - Aug 12 2002
Externally published	Yes

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@article{8cd8649cfb0843f086bd4c82e4f01852,

title = "How to make a major shift in a Redox potential: Ligand control of the oxidation state of dimolybdenum units",

abstract = "A compound reported earlier (Polyhedron 1989, 8, 2339) as (Bun4N)2H2{Mo2 [Mo(CO)4(PhPO2)2]2} has been reexamined. We find that the hydrogen atoms in this formula are not present. Therefore, the complex must be considered as having a central triply bonded Mo26+ unit, instead of a quadruply bonded Mo24+ unit. Our conclusion is based on a variety of experimental evidence, including X-ray crystal structures of four crystal forms, as well as the neutron crystal structure of one. This explains the relatively long Mo-Mo bond lengths found in the range 2.1874(7)-2.2225(7) {\AA} and the absence of a δ → δ* transition in the visible spectrum. From electrochemistry we also find that the diphosphonate ligand has such an exceptional ability to stabilize higher oxidation states that even common solvents such as CH2CI2 and C2H2OH readily oxidize the Mo24+ unit that is introduced from the Mo2(O2-CCH3)4 or [Mo2(O2CCH3)2 (NCCH3)6](BF4)2 employed in the preparation. The only chemically reversible wave at E1/2 = -1.54 V vs Ag/AgCl corresponds to the reduction process Mo26+ → Mo25+.",

author = "Cotton, {F. Albert} and Daniels, {Lee M.} and Liu, {Chun Y.} and Murillo, {Carlos A.} and Schultz, {Arthur J.} and Xiaoping Wang",

year = "2002",

month = aug,

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doi = "10.1021/ic025632w",

language = "English",

volume = "41",

pages = "4232--4238",

journal = "Inorganic Chemistry",

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publisher = "American Chemical Society",

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T1 - How to make a major shift in a Redox potential

T2 - Ligand control of the oxidation state of dimolybdenum units

AU - Cotton, F. Albert

AU - Daniels, Lee M.

AU - Liu, Chun Y.

AU - Murillo, Carlos A.

AU - Schultz, Arthur J.

AU - Wang, Xiaoping

PY - 2002/8/12

Y1 - 2002/8/12

N2 - A compound reported earlier (Polyhedron 1989, 8, 2339) as (Bun4N)2H2{Mo2 [Mo(CO)4(PhPO2)2]2} has been reexamined. We find that the hydrogen atoms in this formula are not present. Therefore, the complex must be considered as having a central triply bonded Mo26+ unit, instead of a quadruply bonded Mo24+ unit. Our conclusion is based on a variety of experimental evidence, including X-ray crystal structures of four crystal forms, as well as the neutron crystal structure of one. This explains the relatively long Mo-Mo bond lengths found in the range 2.1874(7)-2.2225(7) Å and the absence of a δ → δ* transition in the visible spectrum. From electrochemistry we also find that the diphosphonate ligand has such an exceptional ability to stabilize higher oxidation states that even common solvents such as CH2CI2 and C2H2OH readily oxidize the Mo24+ unit that is introduced from the Mo2(O2-CCH3)4 or [Mo2(O2CCH3)2 (NCCH3)6](BF4)2 employed in the preparation. The only chemically reversible wave at E1/2 = -1.54 V vs Ag/AgCl corresponds to the reduction process Mo26+ → Mo25+.

AB - A compound reported earlier (Polyhedron 1989, 8, 2339) as (Bun4N)2H2{Mo2 [Mo(CO)4(PhPO2)2]2} has been reexamined. We find that the hydrogen atoms in this formula are not present. Therefore, the complex must be considered as having a central triply bonded Mo26+ unit, instead of a quadruply bonded Mo24+ unit. Our conclusion is based on a variety of experimental evidence, including X-ray crystal structures of four crystal forms, as well as the neutron crystal structure of one. This explains the relatively long Mo-Mo bond lengths found in the range 2.1874(7)-2.2225(7) Å and the absence of a δ → δ* transition in the visible spectrum. From electrochemistry we also find that the diphosphonate ligand has such an exceptional ability to stabilize higher oxidation states that even common solvents such as CH2CI2 and C2H2OH readily oxidize the Mo24+ unit that is introduced from the Mo2(O2-CCH3)4 or [Mo2(O2CCH3)2 (NCCH3)6](BF4)2 employed in the preparation. The only chemically reversible wave at E1/2 = -1.54 V vs Ag/AgCl corresponds to the reduction process Mo26+ → Mo25+.

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ER -

How to make a major shift in a Redox potential: Ligand control of the oxidation state of dimolybdenum units

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