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W(CO) 4 (diimine) Structure Revised – Correlating Structure to π* Back‐Bonding
Author(s) -
Makedonas Christodoulos,
Mitsopoulou Christiana A.
Publication year - 2007
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/ejic.200600670
Subject(s) - diimine , chemistry , bond length , bending , molecular geometry , crystallography , derivative (finance) , computational chemistry , stereochemistry , crystal structure , molecule , organic chemistry , composite material , materials science , catalysis , financial economics , economics
Abstract The bending of axial and equatorial carbonyls, one of the main structural features of the M(CO) 4 (diimine) compounds (M = Cr, Mo, and W), is elucidated in terms of the π* back‐bonding theory by a frontier molecular orbital analysis. Employing W(CO) 4 (phen) (phen = 1,10‐phenanthroline) as a reference compound has proved that the deviation from orthogonality stabilizes the structure by a total amount of 2.95 kJ/mol. Moreover, by an extended comparison of severalW(CO) 4 (diimine) structures, the importance of the magnitude of the binding angle in determining the bonding in these complexes in comparison to the traditional approach of the W–C and C–O bond lengths is underlined. As a result, it is proposed that the correct indices of the extent of back‐donation are the deviations of the C–W–C angles from orthogonality and the O–C–W angles from linearity. It is indicated for the first time that the larger the existing deviation the stronger the back‐donation. Moreover, a structure‐to‐properties relation is provided that correlates the bending of the carbonyls to the extent of back‐donation. Back‐donation is expected to be correlated to the electronic properties of the compounds, such as the extent of solvatochromism.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)