Synthesis and characterization of binuclear platinum group metal complexes of novel hexadentate ligands .alpha.,.alpha.'-bis(bis(2-(diphenylphosphino)ethyl)amino)-p-xylene and .alpha.,.alpha.'-bis(bis(2-(diphenylarsino)ethyl)amino)-p-xylene

Abstract

AHS < Am. Moreover, such a crystallographic phase transition can be inferred from the lattice dynamical behavior of spincrossover compounds, as extracted from temperature-dependent s7Fe Miissbauer experiments, as will be reported elsewhere.% Such lattice dynamical data are consistent with the observation that the metal-ligand bond lengths decrease in going from the HS to the LS form of Fe(I1) spin-crossover complexes.The present study affords for the first time a self-consistent data set for comparison of the characteristic temperature for HS LS conversion of Fe(I1) spin-crossover complexes ( T I ) , and the temperature a t which the (trapped) HS form-produced by visible light irradiation of the LS form a t low temperatures-is reannealed to the LS form ( T 2 ) . Such a comparison can be effected for complexes I, IV, and V, the three (isothiocyanato)-(28) Yousif, A.; Herber, R. H., unpublished results.iron(I1) compounds examined in detail in the VTFTIR experiments discussed above. The present data suggest that a lower T2 is associated with a lower TI for a given complex, suggesting that the lower thermal excitation required to "freeze-in" the LS form of a given complex is also required to "freeze-in" the (trapped) HS form produced by optical excitation of the LS form matrix.Clearly, the present data can only be considered as suggestive of such a relationship between T I and T2, and further experiments to explore this behavior are currently under way. Acknowledgment. Synthesis and Characterization of Binuclear Platinum Group Metal Complexes of Novel Hexadentate Ligands a,a'-Bis(bis( 2-( dipheny1phosphino)ethyl)amino)-p -xylene and a,a'-Bis( bis( 2-( dipheny1arsino)ethyl)amino)-p -xyleneThe hexadentate ligands cY,cY'-bis(bis(2-(diphenylphosphino)ethyl)amino)-~-xylene (PXBDPA) and a,a'-bis(bis(2-(diphenyl-arsin0)ethyl)amino)-p-xylene (PXBDAA) were synthesized and characterized on the basis of their 'H, ,IP, and NMR spectra. Binuclear metal complexes of these ligands with Ru(II), Ru(III), Rh(I), Ir(I), Pd(II), and Pt(I1) are reported. Reaction of RuCI2(PPh3), with PXBDPA or PXBDAA in benzene in a 2:l ratio gave neutral, binuclear Ru(1I) complexes of the type [Ru2CI4(PPh,),(L)] (L = PXBDPA, PXBDAA). The salt [Ru~C~~(M~~SO),(PXBDPA)](PF~)~ was obtained by the reaction of RuCI,(M~,SO)~, PXBDPA, and NH4PF6 in an ethanol-benzene mixture. Neutral, binuclear, and octahedral complexes of the type [Ru2CI6(L)] (L = PXBDPA, PXBDAA) were obtained by the reaction of L with RuC1,(AsPh3),MeOH in benzene. Reaction of RuBr,(AsPh,),MeOH with PXBDPA or PXBDAA yielded Ru(II1) complexes of the composition [Ru2Br,-(AsPh,),(L)]Br, (L = PXBDPA, PXBDAA). The reaction of [Rh(COD)CI], or [Ir(COD)Cl], with PXBDPA or PXBDAA in an ethanol-benzene mixture yielded neutral, binuclear, and square-planar complexes of the type [M,CI,(L)] (M = Rh, Ir; L = PXBDPA, PXBDAA). Binuclear, square-planar cationic complexes of the composition [Rh,(S),(L)] (PF6), (S = PPh,, CH,CN; L = PXBDPA, PXBDAA) were obtained by the reaction of [Rh(COD)CI],, L, and PPh, or ac...

Synthesis and Reactivity of Ru-, Os-, Rh-, and Ir-Halide−Sulfoxide Complexes

“…247 The reaction of 8 in refluxing ethanol with 0.5 equiv the bis-tridentate bridging ligand (Ph 2 PCH 2 CH 2 ) 2 NCH 2 C 6 H 4 CH 2 N(Ph 2 -PCH 2 CH 2 ) 2 , in which the two NP 2 moieties are separated by a p-xylyl bridge, afforded a complex tentatively formulated as the dinuclear cation [RuCl-(dmso-S) 2 (µ-P 2 N-NP 2 )RuCl(dmso-S) 2 ] 2+ . 248 Treament of 8 with 1 equiv of the tridentate N,P,N ligand bis-(2-oxazolin-2-ylmethyl)phenylphosphine (oxzp, Chart 20) in refluxing toluene afforded the well characterized fac-RuCl 2 (dmso-S)(oxzp) complex, with the phosphorus atom cis to one chloride and to the dmso ligand (Scheme 26). 249 Treatment of 8 with 2 equiv of the potentially tridentate P 2 As ligand (Ph 2 PCH 2 ) 2 AsPh (dpma) in dichloromethane at room temperature afforded transRuCl 2 (dpma) 2 ; the X-ray structure determination showed that in the complex one dpma ligand binds to Ru through the two P atoms, forming a sixmembered chelate ring, with the internal As atom uncoordinated, while the other dpma ligand is bound through the As and a P atoms, forming a fourmembered chelate ring, with the remaining P atom uncoordinated (Scheme 27).…”

“…Treatment of 8 with 2 equiv of the NP 2 tridentate ligand PhCH 2 N(CH 2 CH 2 PPh 2 ) 2 (dpba) in refluxing acetone yielded the poorly characterized cationic complex [RuCl(dmso-S) 2 (dpba)]Cl; under the same reaction conditions, the corresponding NAs 2 ligand (daba) apparently produced instead the neutral complex RuCl 2 (dmso-S)(daba) . The reaction of 8 in refluxing ethanol with 0.5 equiv the bis-tridentate bridging ligand (Ph 2 PCH 2 CH 2 ) 2 NCH 2 C 6 H 4 CH 2 N(Ph 2 PCH 2 CH 2 ) 2 , in which the two NP 2 moieties are separated by a p -xylyl bridge, afforded a complex tentatively formulated as the dinuclear cation [RuCl(dmso-S) 2 (μ-P 2 N−NP 2 )RuCl(dmso-S) 2 ] 2+ . Treament of 8 with 1 equiv of the tridentate N,P,N ligand bis(2-oxazolin-2-ylmethyl)phenylphosphine (oxzp, Chart ) in refluxing toluene afforded the well characterized fac -RuCl 2 (dmso-S)(oxzp) complex, with the phosphorus atom cis to one chloride and to the dmso ligand (Scheme ) …”

The influence of trinuclear complexes on light-induced hydrogen production

“…Similar systems of the mono-and bis-ligand with phenyl instead of anisyl groups already exist. 6,15,[17][18][19][20][21] In this study, we present, to the best of our knowledge, for the first time, an anisyl containing PNP-ligand with multiple coordination sites to produce trimetallic complexes. Their mononuclear relatives do not exhibit the benzene function.…”

“…Their mononuclear relatives do not exhibit the benzene function. 19,[22][23][24] The size of the ligand sphere directly influences the reactivity of the attached metal centre and, therefore, subsequent catalysis. Bulky ligands influence bond distances as well as steric compression.…”

“…Similar systems of the mono- and bis-ligand with phenyl instead of anisyl groups already exist. 6,15,17–21…”