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From a PGeP Pincer-Type Germylene to Metal Complexes Featuring Chelating (Ir) and Tripodal (Ir) PGeP Germyl and Bridging (Mn2) and Chelating (Ru) PGeP Germylene Ligands

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journal contribution
posted on 03.05.2018, 16:06 by Javier Brugos, Javier A. Cabeza, Pablo García-Álvarez, Enrique Pérez-Carreño
Different coordination modes of a PGeP chloridogermyl ligand (Ge,P-chelating and P,Ge,P-tripodal) and a PGeP germylene ligand (P,Ge,P-bridging and Ge,P-chelating) have been identified in coordination compounds resulting from reactions of the PGeP pincer-type diphosphane-germylene Ge­(NCH2PtBu2)2C6H4 (1) with iridium­(I), manganese(0), and ruthenium­(II) complex reagents. Germylene 1 reacted with [Ir2(μ-Cl)24-cod)2] (cod = 1,5-cyclooctadiene) to give [Ir­{κ2Ge,P-GeCl­(NCH2PtBu2)2C6H4}­(η4-cod)] (2), which contains a Ge,P-chelating PGeP chloridogermyl ligand and an uncoordinated phosphane group that weakly interacts with the Ge atom. Carbon monoxide readily displaced the cod ligand of 2 to give the dicarbonyl derivative [Ir­{κ3P,Ge,P-GeCl­(NCH2PtBu2)2C6H4}­(CO)2] (3), in which the PGeP chloridogermyl ligand displays a P,Ge,P-tripodal coordination mode. A bridging germylene moiety has been identified in the binuclear derivative [Mn2{μ-κ3P,Ge,P-Ge­(NCH2PtBu2)2C6H4}­(CO)8] (4), which resulted from the treatment of [Mn2(CO)10] with germylene 1. The ruthenium complex [RuHCl­(CO)­{κ2Ge,P-Ge­(NCH2PtBu2)2C6H4}­(PiPr3)] (5), which was isolated from the reaction of 1 with [RuHCl­(CO)­(PiPr3)2], is the first transition-metal derivative of 1 in which the germylene moiety has not inserted into an M–M or M–Cl bond (M = transition metal), as it contains germylene 1 coordinated in a Ge,P-chelating mode, the resulting GeNCPRu ring being severely strained due to the short length of the coordinated CH2PtBu2 arm, which also forces the germanium atom to be in an uncommon T-shaped environment. DFT calculations have been used to shed light on bonding features of complexes 2 and 5. The X-ray structures of 15 are also reported.