Synthesis and properties of mono- and bi-metallic complexes with neutral group 16 donor ligands

Abstract

The novel tetradentate ligands C(CH2SeCH3)4 and C6H2(CH2ECH3)4 (E= S, Se, Te) were prepared and characterised by multinuclear NMR (1H, 13C{1H}, 77Se{1H} and 125Te{1H}), IR spectroscopy, mass spectrometry, elemental analysis and in some cases single crystal X-ray diffraction. Synthesis of C(CH2SeCH3)4 was shown to produce the cyclopropyl ligand (CH2)2C(CH2SeCH3)2 and dimethyl selenide as side products. The attempted synthesis of C(CH2TeCH3)4 yielded only (CH2)2C(CH2TeCH3)2 and dimethyl telluride.
The metal carbonyl reagents [Mo(CO)4(nbd)], [W(CO)4(tmpa)] and [Mn(CO)5Cl] were reacted with a series of ligands to form both monometallic and homo-bimetallic carbonyl complexes. Monometallic species containing each of the metal centres were produced by reacting the bidentate ligands; C6H4(CH2EMe) (E= S, Se) and (CH2)2C(CH2EMe)2 (E= Se, Te) under appropriate conditions. Both monometallic and homo-bimetallic complexes were produced by reacting the metal reagents with tetradentate ligands C(CH2EMe)4 and 1,2,4,5-C6H2(CH2EMe)4 (E= S, Se). These compounds were characterised using multinuclear NMR (1H, 13C{1H}, 55Mn, 77Se{1H} and 95Mo), IR spectroscopy, APCI mass spectrometry, elemental analysis and single crystal X-ray diffraction. Crystal structures of [Mo(CO)4{o-C6H4(CH2SeMe)2}], [Mo(CO)4{?-C6H4(CH2SMe)4}Mo(CO)4], [Mo(CO)4{C6H4(CH2SMe)4}], [Mo(CO)4{C6H4(CH2SeMe)4}], [Mn(CO)3Cl{?-C6H4(CH2SMe)4}Mn(CO)3Cl], [W(CO)4{C(CH2SMe)4}], [Mo(CO)4{?-C(CH2SMe)4}Mo(CO)4] and [Mn(CO)3Cl{C(CH2SMe)4}] and fac-[Mn(CO3)Cl{(CH2)C(CH2TeMe)2}] have been determined. Examples of both meso and DL isomers can be seen in these structures and does not seem to be driven by ligand type or which metal centre is present. Monometallic carbonyl compounds were shown to dissociate in solution making them unsuitable for production of hetero-bimetallic species.
{MCl(?6-arene)}+ (M= Ru, Os) fragments were shown to form stable monometallic and homo-bimetallic complexes when reacted with the tetradentate ligands C(CH2EMe)4 and C6H2(CH2EMe) (E= S, Se). [{OsCl(?6-p-cymene)}2{?2?,2-C(CH2EMe)4}]2+ (E= S/Se) showed slow pyramidal inversion, as evidenced by multinuclear NMR studies, with individual invertomers being observed. The distribution of each invertomer was unequal, with the dominant form being meso. Crystal structures of [RuCl(?6-p-cymene){?2-C(CH2EMe)4}][PF6], [RuCl(?6-p-cymene){?2-1,2,4,5-C6H2(CH2SMe)4}][BPh4], [RuCl(?6-p-cymene){?2-1,2,4,5-C6H2(CH2SeMe)4}][BPh4], [{RuCl(?6-p-cymene)}2{?2?,2-1,2,4,5-C6H2(CH2SMe)4}][PF6]2 and [{RuCl(?6-p-cymene)}{(CH2)2C(CH2SMe)4}][PF6]2 have been determined. In each case the EMe groups were present as a meso invertomer with both methyl groups directed away from the arene ligand. A monometallic osmium complex was shown to be a suitable starting material for production of the hetero-bimetallic compound, [{OsCl(?6-p-cymene)}{PtCl2}{?2,?’2-C(CH2SeMe)4}][PF6].
A series of Group 13 complexes were produced by reacting GaCl3 and InCl3 with C6H4(CH2SMe)4, C6H4(CH2SEt), (CH2)2C(CH2EMe)2 (E= Se, Te), C(CH2EMe)4 and 1,2,4,5-C6H2(CH2EMe)4 (E= S, Se). GaCl3 formed compounds with tetrahedral geometry, InCl3 produced compounds with octahedral geometries and variable stoichiometries. [(GaCl3)2o-C6H4(SMe)2] undergoes further reaction in solution yielding [o-C6H4(SMeCH2Cl)2][GaCl4]2. Crystal structures of [o-C6H4(SMeCH2Cl)2][GaCl4]2, [(GaCl3)2{o-C6H4(CH2SEt)2}3], [(InCl3)4{o-C6H4(CH2SEt)2}3] have been determined.

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ORCID for Gillian Reid: orcid.org/0000-0001-5349-3468

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