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(NCH2P
t
Bu2)2C6H4 (1) with iridium(I), manganese(0), and ruthenium(II) complex reagents.
Germylene 1 reacted with [Ir2(μ-Cl)2(η4-cod)2] (cod = 1,5-cyclooctadiene)
to give [Ir{κ2
Ge,P-GeCl(NCH2P
t
Bu2)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{κ3
P,Ge,P-GeCl(NCH2P
t
Bu2)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-κ3
P,Ge,P-Ge(NCH2P
t
Bu2)2C6H4}(CO)8] (4), which resulted
from the treatment of [Mn2(CO)10] with germylene 1. The ruthenium complex [RuHCl(CO){κ2
Ge,P-Ge(NCH2P
t
Bu2)2C6H4}(P
i
Pr3)] (5), which
was isolated from the reaction of 1 with [RuHCl(CO)(P
i
Pr3)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 CH2P
t
Bu2 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.