
%0 Journal Article
%A Munk, V. P. 
%A Cham, S. T. 
%A Fenton, R. R. 
%A Hocking, R. K. 
%A Hambley, T. W. 
%T Insights into the van der Waals Radius of Low-Spin Ni(ii) fromMolecular Mechanics Studies and the Crystal Structures of [Ni(<emph type="2">cis-</emph>cyclohexane-1,3-diamine)<emph type="8">2</emph>]Cl<emph type="8">2</emph>, [Ni{(<emph type="2">R</emph>)-5,5,7-trimethyl-1,4-diazacycloheptane}<emph type="8">2</emph>]Cl<emph type="8">2</emph>·H<emph type="8">2</emph>O and [Ni(5,7-dimethyl-1,4-diazacycloheptane)<emph type="8">2</emph>](ClO<emph type="8">4</emph>)<emph type="8">2</emph>. Synthesis of 5,7-Dimethyl-1,4-diazacycloheptane and an Improved Synthesis of <emph type="2">cis-</emph>Cyclohexane-1,3-diamine
%J Australian Journal of Chemistry
%D 2002/10/11
%V 55
%N 8
%P 523-529
%K 
%R https://doi.org/10.1071/CH02099
%U https://www.publish.csiro.au/paper/CH02099 
%X The structures of three bis(diamine)nickel(II) complexes, chosen to shed light on the van der Waals radius of nickel(II), are described. [Ni(cis-1,3-chxn)2]Cl2 (cis-1,3-chxn = cis-cyclohexane-1,3-diamine) crystallizes in the monoclinic space group P21/n, with a 6.397(2), b 16.463(4), c 7.229(2) &#197;, b 90.70(2)°, and its structure has been refined to an R value of 0.031 on 1214F. [Ni{(R)-tmdz}2]Cl2·H2O (tmdz = 5,5,7-trimethyl-1,4-diazacycloheptane) crystallizes in the orthorhombic space group P212121, with a 10.678(1), b 11.073(5), c 17.968(6) &#197;, and its structure has been refined to an R value of 0.031 on 1586F. [Ni(dmdz)2](ClO4)2 (dmdz = 5,7-dimethyl-1,4-diaza- cycloheptane) crystallizes in the monoclinic space group P21/n, with a 9.582(1), b 10.390(2), c 11.817(3) &#197;, &#946; 96.19(2)°, and its structure has been refined to an R value of 0.059 on 817F. In all three structures, short Ni···H and Ni···C interactions, ranging from 2.37 to 2.61 &#197; and 2.99 to 3.03 &#197;, respectively, are observed. Using molecular mechanics modelling to reproduce these separations, we have arrived at a van der Waals radius of 1.35 &#197; for low-spin nickel(ii). Analysis of Ni···O contacts in the solid state leads to a van der Waals radius of about 1.26 &#197;, which is consistent with the molecular mechanics derived value since these are usually longer. 
