The diastereomerically pure complexes [TpRuX(R,R-dippach)] (X ) Cl (1a), H (2a); R,Rdippach ) (R,R)-1,2-bis((diisopropylphosphino)amino)cyclohexane) as well as the nonchiral derivatives [TpRuX(dippae)] (X ) Cl (1b), H (2b); dippae ) 1,2-bis((diisopropylphosphino)amino)ethane) have been prepared and characterized. The reaction of either 1a or 1b with H 2 and NaBAr′ 4 (Ar′ ) 3,5-bis(trifluoromethyl)phenyl) in fluorobenzene yields the corre-No significant intramolecular interaction between the amino protons and the hydrogen atoms bound to the metal has been observed in any of these compounds. Both 3a and 3b react readily with dinitrogen, furnishing the complexes [TpRu(N 2 )(R,Rdippach)][BAr′ 4 ] (4a) and [TpRu(N 2 )(dippae)][BAr′ 4 ] (4b). The X-ray crystal structures of 3b and 4b were determined. The proton-transfer processes over the monohydrides 2a and 2b with HBF 4 ‚OEt 2 have been studied by NMR spectroscopy. Dicationic dihydrogen complexes [TpRu(H 2 )(R,R-dippachH)] 2+ (5a) and [TpRu(H 2 )(dippaeH)] 2+ (5b) result from the protonation of 2a and 2b at one of the NH groups of the respective phosphinoamine ligands by an excess (>10 equiv) of HBF 4 . These species undergo slow tautomerization to their monohydride isomers [TpRuH(R,R-dippachH 2 )] 2+ (5a) and [TpRuH(dippaeH 2 )] 2+ (5b). Intermediates having short hydride (T 1 ) min values have been detected in the course of the proton transfer reactions, which possibly involve the formation of dihydrogen-bonded complexes and/or contact ion pairs between the monohydride complex and the proton donor. Finally, the reaction of 2a with less than 1 equiv of HBF 4 at -80 °C generates a hydride species having an extremely short (T 1 ) min value of 0.5 ms at -62 °C and 400 MHz. The causes for this fast relaxation phenomenon are so far unknown.

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The syntheses of the chloro complexes [Ru(eta5-C5R5)Cl(L)] (R = H, Me; L = phosphinoamine ligand) (1a-d) have been carried out by reaction of [(eta5-C5H5)RuCl(PPh3)2] or {(eta5-C5Me5)RuCl}4 with the corresponding phosphinoamine (R,R)-1,2-bis((diisopropylphosphino)amino)cyclohexane), R,R-dippach, or 1,2-bis(((diisopropylphosphino)amino)ethane), dippae. The chloride abstraction reactions from these compounds lead to different products depending on the starting chlorocomplex and the reaction conditions. Under argon atmosphere, chloride abstraction from [(eta5-C5Me5)RuCl(R,R-dippach)] with NaBAr'4 yields the compound [(eta5-C5Me5)Ru(kappa3P,P'-(R,R)-dippach)][BAr'4] (2b) which exhibits a three-membered ring Ru-N-P by a new coordination form of this phosphinoamine. However, under the same conditions the reaction starting from [(eta5-C5Me5)RuCl(dippae)] yields the unsaturated 16 electron complex [(eta5-C5Me5)Ru(dippae)][BAr'4] (2d). The bonding modes of R,R-dippach and dippae ligands have been analyzed by DFT calculations. The possibility of tridentate P,N,P-coordination of the phosphinoamide ligand to a fragment [(eta5-C5Me5)Ru]+ is always present, but only the presence of a cyclohexane unit in the ligand framework converts this bonding mode in a more favorable option than the usual P,P-coordination. Dinitrogen [(eta5-C5R5)Ru(N2)(L)][BAr'4] (3a-d) and dioxygen complexes [(eta5-C5H5)Ru(O2)(R,R-dippach)][BPh4] (4a) and [(eta5-C5Me5)Ru(O2)(L)][BPh4] (4b,d) have been prepared by chloride abstraction under dinitrogen or dioxygen atmosphere, respectively. The presence of 16 electron [(eta5-C5H5)Ru(R,R-dippach)]+ species in fluorobenzene solutions of the corresponding dinitrogen or dioxygen complexes in conjunction with the presence of [BAr'4]- gave in some cases a small fraction of [Ru(eta5-C5H5)(eta6-C6H5F)][BAr'4] (5a), which has been isolated and characterized by X-ray diffraction.

The complexes [(C5R5)RuH(dippae)] [R = H (1a), Me (2a); dippae = 1,2-bis(diisopropylphosphinoamino)ethane] and [(C5R5)RuH((R,R)-dippach)] [R = H (1b), Me (2b); (R,R)-dippach = (R,R)-1,2-bis(diisopropylphosphinoamino)cyclohexane] have been prepared and characterized. The cationic ruthenium(IV) dihydride derivatives [(C5R5)RuH2(dippae)][BPh4] [R = H (3a), Me (4a)] and [(C5R5)RuH2((R,R)-dippach)][BPh4] [R = H (3b), Me (4b)] are also reported. No significant intramolecular interaction between the amino protons and the hydrogen atoms bound to the metal has been observed in any of these compounds. The X-ray crystal structure of 4a was determined. The proton-transfer processes over the monohydrides 2a and 2b with HBF4.OEt2 have been studied by NMR spectroscopy. Dicationic dihydride complexes [CpRuH2(LH)]2+ [LH = dippaeH+ (5a), (R,R)-dippachH+ (5b)] and [Cp*RuH2(LH)]2+ [LH = dippaeH+ (6a), (R,R)-dippachH+ (6b)] result respectively from the protonation of either the monohydrides 1a,b or 2a,b or the dihydrides 3a,b or 4a,b at one of the NH groups of the phosphinoamine ligands by an excess of HBF4. These dicationic derivatives exhibit fluxional behavior in solution. In the course of the protonation of 1a with HBF4.OEt2, a cationic dihydrogen complex and a dihydrogen-bonded derivative have been identified as intermediates by NMR spectroscopy. Another dihydrogen species, namely, [CpRu(H...HOOCPh)((R,R)-dippach)], was also identified in the course of the reaction of 1b with benzoic acid in toluene-d8. The reaction of 1a with 0.5 equiv of 1,1,1,3,3,3-hexafluoroisopropanol generates a hydride species having a very short (T1)min of 6.5 ms at 400 MHz, an experimental fact for which no satisfactory explanation has yet been found.

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The reactions of [Cp*RuCl(CO)(PMe i Pr 2 )] ( 1) and [Cp*RuCl(CO)(PEt 3 )] (2) with NaBAr′ 4 in fluorobenzene both under argon and under dinitrogen generate the binuclear compounds [{Cp*Ru(CO)(PMe i Pr 2 )} 2 (µ-Cl)][BAr′ 4 ] (3) and [{Cp*Ru(CO)(PEt 3 )} 2 (µ-Cl)][BAr′ 4 ] (4), respectively, which were fully characterized. The crystal structure of compound 4 is reported, showing for the first time two chiral "Cp*Ru" fragments bonded through only one bridging chloride ligand. No dinitrogen complexes or 16-electron species could be isolated. Halide abstraction from 1 using dry acetone as solvent yields the compound [Cp*Ru(CO){η 1 -OC-(CH 3 ) 2 }(PMe i Pr 2 )][BAr′ 4 ] (5). A range of olefins react with [Cp*RuCl(CO)(PMe i Pr 2 )] and NaBAr′ 4 furnishing the corresponding cationic η 2 -alkene complexes [Cp*Ru(CO)(L)(PMe i -Pr 2 )][BAr′ 4 ] (L ) C 2 H 4 , 6; H 2 CdCHPh, 7; and H 2 CdCHCOOCH 3 , 8), which are stable under argon atmosphere in solution. The crystal structure of compound 6 is also reported. Both 1 and 2 react with SnCl 2 in CH 2 Cl 2 to yield the insertion derivatives [Cp*Ru(CO)(SnCl 3 )-(PR 3 )] (PR 3 ) PMe i Pr 2 , 9; PEt 3 , 10), which have also been characterized.

The double stranded Cu II 2 metallacyclic complex of formula [Mn(hfac) 2 (H 2 O) 2 ][Cu 2 (mbpb) 2 (CH 3 CN) 2 ] (1) and the triple stranded Ni II 2 , Zn II 2 and Co III 2 metallacyclic complexes of formula [M 2 (Hmbpb) 3 ]XÁnH 2 O (M = Zn II , X = NO 3 À (2), n = 17; M = Ni II , and X = ClO 4 À (3), n = 15) and [Co 2 (mbpb) 3 ]Á19H 2 O (4) (H 2 mbpb is the bisbidentate dinucleating bridging ligand, 1,3-bis(pyridine-2-carboxamide)benzene) have been prepared and structurally characterised. Their X-ray structures show that inside the dinuclear molecules metal ions are bridged by either fully or semideprotonated bisbidentate ligands, which are coordinated through the pyridine and amidato nitrogen donor atoms. In 1, the neutral metallamacrocycle dinuclear entities [Cu 2 (mbpb) 2 (CH 3 CN) 2 ] and the [Mn(hfac) 2 (H 2 O) 2] molecules are connected by hydrogen bonds to afford a 1D system. These intermolecular interactions overcome the expected intradinuclear weak ferromagnetic interaction leading to an overall weak antiferromagnetic interaction. The Ni 2 complex exhibit ferromagnetic coupling between the metal ions through the bridging ligand with J Ni-Ni = 3.1 cm À1 . DFT calculations were performed to estimate the value of the exchange magnetic coupling inside the dinuclear unit in 1 and to confirm that the spin polarisation mechanism is responsible for the ferromagnetic coupling. AFM studies show that the Zn II 2 and Ni II 2 cationic complexes interact with pBR322 DNA producing supercoiled forms in higher extension as well as kinks and cross linking.

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