Chromium complexes of hydroxyl-functionalised 1,3,5-triazacyclohexanes

Abstract

The chromium co-ordination chemistry of three 1,3,5-triazacyclohexanes bearing hydroxyl-functionalised substituents on nitrogen has been explored. The complexeshave been prepared. Characterisation of the carbonyl complexes by spectroscopic and structural methods indicated that the triazacyclohexanes co-ordinate to the chromium centre through the three nitrogen atoms only. Crystal structure determinations for 1,3,5-tri-(o-hydroxybenzyl)-1,3,5-triazacyclohexane and [Cr(CO) 3 (C 3 H 6 N 3 R 3 )] (R = CH 2 CH 2 OH or CH 2 CH 2 CH 2 OH) have been made.

A Frustrated [Mn18] Wheel-of-Wheels

“…A search of the Cambridge Structural Database (CSD) reveals just four hits in 3d transition metal chemistry. The first was the monomer [Cr(CO)3(LH3)], 15 the second an aesthetically pleasing [Mn16] complex in which the ligand was generated serendipitously in-situ, 16 and the third and fourth structurally related [Mn16] and [Mn10] square wheels. 17…”

A [Mn18] wheel-of-wheels

“…A search of the Cambridge Structural Database reveals just four hits in 3d transition metal chemistry. The first was the monomer [Cr(CO) 3 (LH 3 )], 15 the second an aesthetically pleasing [Mn 16 ] complex in which the ligand was generated serendipitously in situ, 16 Compound 1 crystallises in the monoclinic space group I2/a, with half the complex in the asymmetric unit. The metallic skeleton of 1 describes two distorted 'square' [Mn III 6 Mn II 2 ] wheels (Mn1-7) linked via two Mn II ions (Mn8).…”

Preparation of Complexes η4-4-(1,3-Diphenyl-2-propen-1-one)-η3-3-(1,3,5-triorganyl-1,3,5-triazacyclohexane)carbonyltungsten(0) and Their Reactions with Diethyl Phosphite

“…Therefore its tridentate coordination with the metal center is characterized by a certain strain that might result in unpredictable changes in reactivity of the complexes including these systems. Relatively simple procedures for preparation of complexes (1,3,5-trialkyl-1,3,5-triazacyclohexane)metal(CO) 3 were reported in [2 5], and it was shown that notwithstanding the character of substituents at the nitrogen atom, for instance, alkyne [4] or hydroxyalkyl groups [5], in the chromium and in some cases in molybdenum complexes a tridentate n-coordination of the triazinane with metal was observed occurring at the expense of the unshared electron pairs of nitrogen.We formerly developed preparation procedures for organometallic compounds starting from a-enones and homoligand hexacarbonyl complexes of metals from the chromium subgroup and investigated hydrophosphorylation of unsaturated ligand within the coordination sphere of metal [6,7]. This study permit us establishing a fundamental possibility to govern hydrophosphorylation regioselectivity of a-enones included into the coordination sphere of a transition metal.…”

“…Therefore its tridentate coordination with the metal center is characterized by a certain strain that might result in unpredictable changes in reactivity of the complexes including these systems. Relatively simple procedures for preparation of complexes (1,3,5-trialkyl-1,3,5-triazacyclohexane)metal(CO) 3 were reported in [2 5], and it was shown that notwithstanding the character of substituents at the nitrogen atom, for instance, alkyne [4] or hydroxyalkyl groups [5], in the chromium and in some cases in molybdenum complexes a tridentate n-coordination of the triazinane with metal was observed occurring at the expense of the unshared electron pairs of nitrogen.…”