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The reaction of RuHCl(PPh3)3 with GaMe3 gives rise to the arene complex [(η6-C6H6)Ru(PPh3)(PPh2-o-C6H4-GaClMe], 1, with the Ga atom making part of an in situ generated ambiphilic phosphinogallyl ligand in a five-membered ruthenagallacycle ring with a tetracoordinate gallium. In the presence of excess GaMe3, 1 forms complex [(η6-C6H6)Ru(PPh3)(PPh2-o-C6H4-GaMe][GaMe3Cl], 2 also bearing a phosphinogallyl ligand. Crystals suitable for single-crystal X-ray diffraction were obtained of complex 2′, [(η6-C6H6)Ru(PPh3)(PPh2-o-C6H4-GaMe][GaMe2Cl2], showing an ion pair with two Ga atoms in different coordination environments: the first with a coordination number of three makes part of a five-membered ruthenagallacyle ring, while the second Ga atom is a gallate anion. In both complexes 1 and 2, the Ga atom binds to Ru as a σ-acceptor Z-type ligand. DFT calculations are in good agreement with the experimental single crystal X-ray diffraction data and provide Ru-Ga Wiberg bond indexes of 0.38 and 0.50, for 1 and 2 respectively. In contrast, treatment of RuHCl(PPh3)3 with GaMeCl2 and of RuCl2(PPh3)3 with GaMe3 gives rise to gallate species [(η6-C6H6)Ru(PPh3)2H][GaMeCl3], 3, and [(η6-C6H6)Ru(PPh3)2Me][GaMe2Cl2], 4, respectively. 

The formation of dimer [(μ-Cl)Rh-(κ3(P,Si,Si)PhP(o-C6H4CH2SiiPr2)(o-C6H4CH2SiiPrnPr))]2 (Rh-3) with an n-propyl group on one of the silicon atoms as a minor product was affected by the reaction of [RhCl(COD)]2 with proligand PhP(o-C6H4CH2SiHiPr2)2, L1. The major product of the reaction was monomeric 14-electron Rh(III) complex [ClRh(κ3(P,Si,Si)PhP(o-C6H4CH2SiiPr2)2)] (Rh-1). Computations revealed that the monomer–dimer equilibrium is shifted toward the monomer with four isopropyl substituents on the two Si atoms of the ligand as in Rh-1; conversely, the dimer is favored with only one n-propyl as in Rh-3, and with less bulky alkyl substituents such as in [ClRh(κ3(P,Si,Si)PhP(o-C6H4CH2SiMe2)2]2 (Rh-2). Computations on the mechanism of formation of Rh-3 directly from [RhCl(COD)]2 are in agreement with the experimental findings and it is found to be less energetic than if stemming from Rh-1. Additionally, a Si–O–Si complex, [μ-Cl-Rh{κ3(P,Si,C)PPh(o-C6H4CH2SiiPrO SiiPr2CH-o-C6H4)}]2, Rh-4, is generated from the reaction of Rh-1 with adventitious water as a result of intramolecular C–H activation. 

The new material [RuGa]@NU-1000 incorporates Ru and Ga in 1.2 and 1.8 wt% respectively (molar ratio 1 : 2). It stems from the grafting of the heterobimetallic ruthenium gallate complex, [MeRu(η 6 -C 6 H 6 )(PPh 3 ) 2 ][GaMe 2 Cl 2 ] into the MOF material NU-1000. [RuGa]@NU-1000 shows enhanced adsorption of SO 2 , specially at low pressures (10 −3 bar) even when compared with other materials employing more expensive precious metals. Additionally, [RuGa]@NU-1000 samples need not be exposed to such harsh conditions for reactivation as they retain their adsorption properties after several cycles and preserve their porosity and structure. Thus, [RuGa]@NU-1000 is an excellent, selective material suitable for detection and precise quantification of SO 2 , with a lower cost compared to other MOFs incorporating precious metals.