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Synthesis, structural studies, and redox chemistry of bimetallic [Mn(CO)₃] and [Re(CO)₃] complexes

Henke, Wade C. and Kerr, Tyler A. and Sheridan, Thomas R. and Henling, Lawrence M. and Takase, Michael K. and Day, Victor W. and Gray, Harry B. and Blakemore, James D. (2021) Synthesis, structural studies, and redox chemistry of bimetallic [Mn(CO)₃] and [Re(CO)₃] complexes. Dalton Transactions, 50 (8). pp. 2746-2756. ISSN 1477-9226.

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Manganese ([Mn(CO)₃]) and rhenium tricarbonyl ([Re(CO)₃]) complexes represent a workhorse family of compounds with applications in a variety of fields. Here, the coordination, structural, and electrochemical properties of a family of mono- and bimetallic [Mn(CO)₃] and [Re(CO)₃] complexes are explored. In particular, a novel heterobimetallic complex featuring both [Mn(CO)₃] and [Re(CO)₃] units supported by 2,2′-bipyrimidine (bpm) has been synthesized, structurally characterized, and compared to the analogous monomeric and homobimetallic complexes. To enable a comprehensive structural analysis for the series of complexes, we have carried out new single crystal X-ray diffraction studies of seven compounds: Re(CO)₃Cl(bpm), anti-[{Re(CO₃)Cl}₂(bpm)], Mn(CO)₃Br(bpz) (bpz = 2,2′-bipyrazine), Mn(CO)₃Br(bpm), syn- and anti-[{Mn(CO3)Br}₂(bpm)], and syn-[Mn(CO₃)Br(bpm)Re(CO)₃Br]. Electrochemical studies reveal that the bimetallic complexes are reduced at much more positive potentials (ΔE ≥ 380 mV) compared to their monometallic analogues. This redox behavior is consistent with introduction of the second tricarbonyl unit which inductively withdraws electron density from the bridging, redox-active bpm ligand, resulting in more positive reduction potentials. [Re(CO₃)Cl]₂(bpm) was reduced with cobaltocene; the electron paramagnetic resonance spectrum of the product exhibits an isotropic signal (near g = 2) characteristic of a ligand-centered bpm radical. Our findings highlight the facile synthesis as well as the structural characteristics and unique electrochemical behavior of this family of complexes.

Item Type:Article
Related URLs:
URLURL TypeDescription
Henke, Wade C.0000-0002-4574-8544
Kerr, Tyler A.0000-0002-0369-4883
Sheridan, Thomas R.0000-0002-6247-4418
Takase, Michael K.0000-0001-8365-3645
Gray, Harry B.0000-0002-4453-9716
Blakemore, James D.0000-0003-4172-7460
Alternate Title:Synthesis, structural studies, and redox chemistry of bimetallic [Mn(CO)3] and [Re(CO)3] complexes
Additional Information:© The Royal Society of Chemistry 2021. Submitted 22 Oct 2020; Accepted 11 Jan 2021; First published 12 Jan 2021. The authors thank Dr Justin Douglas and Sarah Neuenswander for assistance with NMR and EPR spectroscopy. This work was supported by the U.S. National Science Foundation through awards OIA-1833087 and CHE-1305124. W. C. H. was supported by the U.S. National Institutes of Health Graduate Training Program in the Dynamic Aspects of Chemical Biology (T32 GM008545-25). The authors also acknowledge the U.S. National Science Foundation and U.S. National Institutes of Health for support of the EPR instrumentation (CHE-0946883) and NMR instrumentation (S10OD016360, S10RR024664, and CHE-0320648) used in this study. The Bruker D8 Kappa X-ray diffractometer used for 1 was purchased via an NSF CRIF:MU award to the California Institute of Technology (CHE-0639094). A Dow Next Generation Instrumentation Grant supported the crystallographic studies on 2-anti, 3, 4, 5-syn, 5-anti, and 6-syn. There are no conflicts to declare.
Funding AgencyGrant Number
NIH Predoctoral FellowshipT32 GM008545-25
Issue or Number:8
Record Number:CaltechAUTHORS:20210119-143306682
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Official Citation:Synthesis, structural studies, and redox chemistry of bimetallic [Mn(CO)₃] and [Re(CO)₃] complexes. Dalton Trans., 2021, 50, 2746-2756; DOI: 10.1039/d0dt03666h
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:107553
Deposited By: George Porter
Deposited On:19 Jan 2021 22:49
Last Modified:03 Mar 2021 17:23

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