Heterodimetallic Germanium(IV) Complex Structures with Transition Metals

The hydrothermal synthesis and structural characterization of a number of complex compounds containing the
divalent tris(oxalato-O,O‘)germanate anion, [Ge(C2O4)3]2-, or the neutral bis(oxalate-O,O‘)germanium fragment,
[Ge(C2O4)2], with transition-metal (M) cationic complexes of 1,10‘-phenanthroline (phen) is reported:  [M(phen)3][Ge(C2O4)3]·xH2O [where M2+ = Cu2+ (1a and 1b), Fe2+ (2a and 2b), Ni2+ (3), Co2+ (4); x = 0.2 for 2b], [MGe(phen)2(μ2-OH)2(C2O4)2] [where M2+ = Cd2+ (5) and Cu2+ (6)]. The isolation of two polymorphs with Cu2+ (1a and
1b) and other pseudo-polymorphs for Fe2+ (2a and 2b) was rationalized based on slightly different molar ratios for
the starting materials. All compounds have been characterized using EDS, SEM, vibrational spectroscopy (FT-IR
and FT-Raman), thermogravimetry, and CHN elemental composition and their structure determined on the basis
of single-crystal X-ray diffraction studies. The crystal packing of the different chemical moieties for each series of
compounds was discussed on the basis of the various intermolecular interactions present (strong C−H···π and
weak C−H···O hydrogen-bonding interactions, C−H···π and π−π contacts).