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

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((NCH2PBu2)-Bu-t)(2)C6H4 (1) with iridium(I), manganese(0), and ruthenium(II) complex reagents. Germylene 1 reacted with [Ir-2(mu-Cl)(2)(eta(4)-cod)(2)] (cod = 1,5-cyclooctadiene) to give [Ir{kappa Ge-2,P-GeCl((NCH2PBu2)-Bu-t)(2)C6H4}(eta(4)-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{kappa(3) P,Ge,P-GeCl((NCH2PBu2)-Bu-t)(2)C6H4}(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 [Mn-2{mu-kappa(3) P,Ge,P-Ge(NCH2PtBu2)(2)C6H4}(CO)(8) ] (4), which resulted from the treatment of [Mn-2(CO)(10)] with germylene 1. The ruthenium complex [RuHCl(CO){kappa(2) Ge,P-Ge((NCH2PBu2)-Bu-t)(2)C6H4}((PPr3)-Pr-i)] (5), which was isolated from the reaction of 1 with [RuHCl(CO)((PPr3)-Pr-i)(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 (CH2PBu2)-Bu-t 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 1-5 are also reported.