Structures and spectroscopic characterization of the divalent complexes cis-dibromidotetrakis(2,6-dimethylphenyl isocyanide)iron(II) dichloromethane 0.771-solvate, [FeBr 2(C 9H 9N) 4]·0.771CH 2Cl 2 or cis-FeBr 2(CNXyl) 4·0.771CH 2Cl 2 (Xyl = 2,6-dimethylphenyl), trans-dibromidotetrakis(2,6-dimethylphenyl isocyanide)iron(II), [FeBr 2(C 9H 9N) 4] or trans-FeBr 2(CNXyl) 4, trans-dibromidotetrakis(2,6-dimethylphenyl isocyanide)cobalt(II), [CoBr 2(C 9H 9N) 4] or trans-CoBr 2(CNXyl) 4, and trans-dibromidobis(2,6-dimethylphenyl isocyanide)nickel(II), [NiBr 2(C 9H 9N) 2] or trans-NiBr 2(CNXyl) 2, are presented. Additionally, crystals grown from a cold diethyl ether solution of zero-valent Fe(CNXyl) 5 produced a structure containing a cocrystallization of mononuclear Fe(CNXyl) 5 and the previously unknown dinuclear [Fe(CNXyl) 3] 2(μ 2-CNXyl) 3, namely pentakis(2,6-dimethylphenyl isocyanide)iron(0) tris(μ 2-2,6-dimethylphenyl isocyanide)bis[tris(2,6-dimethylphenyl isocyanide)iron(0)], [Fe(C 9H 9N) 5][Fe 2(C 9H 9N) 9]. The (M)C-N-C(Xyl) angles of the isocyanide ligand are nearly linear for the metals in the +2 oxidation state, for which the ligands function essentially as pure donors. The νCN stretching frequencies for these divalent metal isocyanides are at or above that of the free ligand. Relative to Fe II, in the structure containing iron in the formally zero-valent oxidation state, the Fe-C bond lengths have shortened, the C[triple-bond]N bond lengths have elongated, the (M)C-N-C(Xyl) angles of the terminal CNXyl ligands are more bent, and the νCN stretching frequencies have shifted to lower energies, all indicative of substantial M(dπ)→π* backbonding.
|Original language||English (US)|
|Number of pages||10|
|Journal||Acta Crystallographica Section C: Structural Chemistry|
|State||Published - Aug 1 2019|
Bibliographical noteFunding Information:
Funding for the instrument used to analyse 1 was provided by: National Science Foundation (grant No. CHE-1725028).
The authors acknowledge the US National Science Foundation, and the donors of the Petroleum Research Fund, administered by the American Chemical Society, for funding. The University of Minnesota Chemistry Department is acknowledged for providing and supporting the graduate level course in X-ray crystallography. Students from this course, Kevin J. Erickson, Emily L. Que, Airon Soegianto, Pratik Verma, and Daniel J. Wherritt, are thanked for their assistance with the various crystal structures in this article. Data for the structure of CNXyl were collected on an instrument purchased with funding from the NSF.
- 2 6-dimethylphenyl isocyanide
- IR spectroscopy
- crystal structure
- xylyl isocyanide
PubMed: MeSH publication types
- Research Support, U.S. Gov't, Non-P.H.S.
- Journal Article