Ruthenium carbonyl clusters derived from pyrazolyl substituted diphosphazanes: crystal and molecular structure of a triruthenium cluster featuring a triply bridging &#956;<SUB>3</SUB>-&#951;<SUP>1</SUP>:&#951;<SUP>1</SUP>:&#951;<SUP>1</SUP> coordination mode of pyrazolate moiety

The radical initiated reactions of Ru3(CO)12 with pyrazolyl substituted diphosphazanes Ph2PN(R)PPh(N2C3HMe2-3,5) [R = (S)-&#8727;CHMePh (1) or CHMe2 (2)] proceed via P-N(pyrazole) bond rupture resulting in the formation of phosphido clusters, [Ru3(CO)5(&#956;sb-CO)2(&#956;3-N,N'-&#951;1:&#951;1:&#951;1-N2C3HMe2-3,5){&#956;-P,P'-Ph2PN(R)PPh}] [R = (S)-&#8727;CHMePh (3) or CHMe2 (4)]. The pyrazolate moiety adopts an unusual triply bridging &#956;3-&#951;1:&#951;1:&#951;1-mode of coordination in these clusters

Ruthenium carbonyl clusters derived from pyrazolyl substituted diphosphazanes: Crystal and molecular structure of a triruthenium cluster featuring a triply bridging μ3−η1:η1:η1\mu_{3}-\eta^{1}:\eta^{1}:\eta^{1} coordination mode of pyrazolate moiety\star

The radical initiated reactions of $Ru_{3}(CO)_{12}$ with pyrazolyl substituted diphosphazanes $Ph_{2}PN(R)PPh(N_{2}C_{3}HMe_{2}-3,5)$ $[R = (S)-^*CHMePh(1) or CHMe_{2}(2)]$ proceed via P-N(pyrazole) bond rupture resulting in the formation of phosphido clusters, $[Ru_{3}(CO)_{5}(\mu_{sb}-CO)_{2}(\mu_{3}-N,N'-\eta^{1}:\eta^{1}:\eta^{1}-N_{2}C_{3}HMe_{2}-3,5)$ ${\mu-P,P'-Ph_{2}PN(R)PPh}] [R=(S)-^*CHMePh(3) or CHMe_{2}(4)]$. The pyrazolate moiety adopts an unusual triply bridging $\mu_{3}-\eta^{1}:\eta^{1}:\eta^{1}$-mode of coordination in these clusters

Chalcogen-capped ruthenium carbonyl clusters derived from diphosphazane mono- and dichalcogenides of the type X2P(E)N(R)PX2X_2P(E)N(R)PX_2 and X2P(E)N(R)P(E)X2X_2P(E)N(R)P(E)X_2 (E=SorSe)(E =S\hspace{2mm} or\hspace{2mm}Se)

Reactions of Ru_3(CO)_1_2 with diphosphazane monoselenides $Ph_2PN(R)P(Se)Ph_2$ $[R = (S)-*CHMePh(L^4),R =CHMe_2(L^5)]$ yield mainly the selenium bicapped tetraruthenium clusters $[R\mu_4(\mu_4-Se)_2(\mu-CO)(CO)_8\{\mu-P,P-Ph_2PN$(R)$PPh_2\}]$ (1,3). The selenium monocapped triruthenium cluster [Ru_3(\mu_3-Se)(\mu_s_b-CO)(CO)_7 $\{K^2-P,P-Ph_2PN((S)-\ast CHMePh)PPh_2\}]$ (2) is obtained only in the case of $L_4$. An analogous reaction of the diphosphazane monosulfide $(PhO)_2PN(Me)P(S)(OPh)_2$ $(L^6)$ that bears a strong $\pi$-acceptor phosphorus shows a different reactivity pattern to yield the triruthenium clusters, $[Ru_3(\mu_3-S)(\mu_3-CO)(CO)_7\{\mu-P,P-(PhO)_2PN(Me)$P$(OPh)_2\}]$ (9) (single sulfur transfer product) and $[Ru_3(\mu_3-S)_2(CO)_5\{k^2-P,P-(PhO)_2PN$(Me)P$(OPh)_2\}\{\mu-P,P-(PhO)_2PN$(Me)P$(OPh)_2\}]$(10) (double sulfur transfer product). The reactions of diphosphazane dichalcogenides with $Ru_3(CO)_{12}$ yield the chalcogen bicapped tetraruthenium clusters $[Ru_4(\mu_4-E)_2(\mu-CO)(CO)_8\{\mu-P,P-Ph_2PN$(R)$PPh_2\}]$ [R = (S)-\ast CHMePh, E = S (6); $R = CHMe_2$, E = S (7); $R = CHMe_2$, E = Se (3)]. Such a tetraruthenium cluster $[Ru_4(\mu_4-S)_2(\mu-CO)(CO)_8\{\mu-P,P-(PhO)_2PN(Me)$P$(OPh)_2\}]$ (11) is also obtained in small quantities during crystallization of cluster 9. The dynamic behavior of cluster 10 in solution is probed by NMR studies. The structural data for clusters 7, 9, 10 and 11 are compared and discussed

Octanuclear {Co6W2} aggregate versus mixed valence {Co}3 cluster in the assembling of Co(phen)2Cl2 (phen = 1,10-phenanthroline) with octacyano metallates: a case of non-isotructurality between {W(CN)8}4- and {Nb(CN)8}4-

An unprecedented octanuclear aggregate, [{Co(phen)2}6{W(CN)8}2Cl2] · 2Cl, 2, resulted from the assembling of {Co(phen)2Cl2}, 1, and {W(CN)8}4−. Surprisingly, the reaction with the paramagnetic {Nb(CN)8}4− unit did not afford the homologous {Co–Nb} cluster. Instead the latter building unit undergoes dissociation which led to the formation of a mixed-valence [{CoII(phen)2}{CoIII(phen)(CN)4}2], 3. This observation is in contrast to the usual trend that {NbIV(CN)8}4− forms compounds isostructural to that observed for {MoIV(CN)8}4− and {WIV(CN)8}4−. The structures of the compounds 2 and 3 have been established by single crystal X-ray diffraction. Magnetic behaviors for compounds 1–3 are reported.This work was supported by the Centre Franco-Indien pour la promotion de la Recherche Avancée/Indo-French Centre for the promotion of Advanced Research (Project 3108-3) and by the Région Midi-Pyrénées in the frame of the Communauté de Travail des Pyrénées (CTP, Program 2007).Peer Reviewe

Steric and electronic effects in stabilizing allyl-palladium complexes of "P-N-P" ligands, X<SUB>2</SUB>PN(Me)PX<SUB>2</SUB> (X = OC<SUB>6</SUB>H<SUB>5</SUB> or OC<SUB>6</SUB>H<SUB>3</SUB>Me<SUB>2</SUB>-2,6)

The chemistry of &#951;3-allyl palladium complexes of the diphosphazane ligands, X2PN(Me)PX2 [X = OC6H5 (1) or OC6H3Me2-2,6 (2)] has been investigated.The reactions of the phenoxy derivative, (PhO)2PN(Me)P(OPh)2 with [Pd(&#951;3-1,3-R',R"-C3H3)(&#956;-Cl)]2 (R' = R" = H or Me; R' = H, R" = Me) give exclusively the palladium dimer, [Pd2{&#956;-(PhO)2PN(Me)P(OPh)2}2Cl2] (3); however, the analogous reaction with [Pd(&#951;3-1,3-R',R"-C3H3)(&#956;-Cl)]2 (R' = R" = Ph) gives the palladium dimer and the allyl palladium complex [Pd(&#951;3-1,3-R',R"-C3H3)(1)](PF6) (R' = R" = Ph) (4). On the other hand, the 2,6-dimethylphenoxy substituted derivative 2 reacts with (allyl) palladium chloro dimers to give stable allyl palladium complexes, [Pd(&#951;3-1,3-R',R"-C3H3)(2)](PF6) [R' = R" = H (5), Me (7) or Ph (8); R' = H, R" = Me (6)].Detailed NMR studies reveal that the complexes 6 and 7 exist as a mixture of isomers in solution; the relatively less favourable isomer, anti-[Pd(&#951;3-1-Me-C3H4)(2)](PF6) (6b) and syn/anti-[Pd(&#951;3-1,3-Me2-C3H3)(2)](PF6) (7b) are present to the extent of 25% and 40%, respectively. This result can be explained on the basis of the steric congestion around the donor phosphorus atoms in 2. The structures of four complexes (4, 5, 7a and 8) have been determined by X-ray crystallography; only one isomer is observed in the solid state in each case

Synthesis, Crystal Structure, and Magnetic Properties of Hexanuclear [{MnL2}4{Nb(CN)8}2][\{MnL_2\}_4\{Nb(CN)_8\}_2] and Nonanuclear [{MnL2}6{Nb(CN)8}3][\{MnL_2\}_6\{Nb(CN)_8\}_3] Heterometallic Clusters (L = bpy, phen)

A hexanuclear cyano-bridged $\{Mn^{II}_4Nb^{IV}_2\}$ cluster (1) bearing 2,2'-bipyridine (bpy) as the blocking ligand at manganese is obtained from the reaction of cis-$[MnCl_2(bpy)_2]$ and $K_4[Nb(CN)_8]$. When the blocking ligand is 1,10-phenanthroline (phen), a nonanuclear cluster $\{Mn^{II}_6Nb^{IV}_3\}$ (2) is obtained. The structure of $[\{Mn(bpy)_2\}_4\{Nb(CN)_8\}_2]$ has been solved by single-crystal X-ray crystallography, whereas the phen derivative has been confirmed by means of he structure analysis of the corresponding $W^{IV}$ analogue $[\{Mn(phen)_2\}_6\{W(CN)_8\}_3(H_2O)_2]$. Magnetic measurements revealed S = 9 and 27/2 spin ground states for these aggregates as a result of antiferromagnetic Nb-Mn interaction with $J_{Nb-Mn} = -18.1 cm^{-1}$ (1) and $-13.6 cm^{-1}$ (2)

Synthesis, crystal structure, and magnetic properties of hexanuclear [{MnL<SUB>2</SUB>}<SUB>4</SUB>{Nb(CN)<SUB>8</SUB>}<SUB>2</SUB>] and nonanuclear [{MnL<SUB>2</SUB>}<SUB>6</SUB>{Nb(CN)<SUB>8</SUB>}<SUB>3</SUB>] heterometallic clusters (L=bpy, phen)

A hexanuclear cyano-bridged {MnII4NbIV2} cluster (1) bearing 2,2'-bipyridine (bpy) as the blocking ligand at manganese is obtained from the reaction of cis-[MnCl2(bpy)2] and K4[Nb(CN)8]. When the blocking ligand is 1,10-phenanthroline (phen), a nonanuclear cluster {MnII6NbIV3} (2) is obtained. The structure of [{Mn(bpy)2}4{Nb(CN)8}2] has been solved by single-crystal X-ray crystallography, whereas the phen derivative has been confirmed by means of the structure analysis of the corresponding WIV analogue [{Mn(phen)2}6{W(CN)8}3(H2O)2]. Magnetic measurements revealed S=9 and 27/2 spin ground states for these aggregates as a result of antiferromagnetic Nb-Mn interaction with JNb-Mn=&#8722;18.1 cm&#8722;1 (1) and &#8722;13.6 cm&#8722;1 (2)

Organometallic chemistry of diphosphazanes. Part 26. Ruthenium hydride complexes of chiral and achiral diphosphazane ligands and asymmetric transfer hydrogenation reactions

The half-sandwhich ruthenium chloro complexes bearing chelated diphosphazane ligands, [(eta(5)-Cp)RuCl{kappa(2)-P,P-(RO)(2)PN(Me)P(OR)(2)}] [R = C6H3Me2-2,6] (1) and [(eta(5)-Cp*)RuCl{kappa(2)-P, P-X2PN(R)PYY'}] [R = Me, X = Y = Y' = OC6H5 (2); R = CHMe2, X-2 = C20H12O2, Y = Y' = OC6H5 (3) or OC6H4'Bu-4 (4)] have been prepared by the reaction of CpRu(PPh3)(2)Cl with (RO)(2)PN(Me)P(OR)(2) [R = C6H3Me2-2,6 (L-1)] or by the reaction of [Cp*RuCl2](n) with X2PN(R)PYY' in the presence of zinc dust. Among the four diastereomers (two enantiomeric pairs) possible for the "chiral at metal" complexes 3 and 4, only two diastereomers (one enantiomeric pair) are formed in these reactions. The complexes 1, 2, 4 and [(eta(5)-Cp)RuCl {kappa(2)-P,P-Ph2PN((S)-*CHMePh)PPhY)] [Y = Ph (5) or N2C3HMe2-3,5 (SCSPRRu)-(6)] react with NaOMe to give the corresponding hydride complexes [(eta(5) -Cp)RuH {kappa(2)-P,P-(RO)(2)PN(Me)P(OR)(2)}] (7), [(eta(5)-Cp*)RuH {kappa(2)-P,P'-X2PN(R)PY2)] [R = Me, X = Y = OC6H5 (8); R = CHMe2, X-2 = C20H12O2, Y = OC6H4'Bu-4 (9)] and [(eta(5) -Cp)RuH(kappa(2)-P, P-Ph2PN((S)-*CHMePh)PPhY)][Y =Ph (10) or N2C3HMe2-3,5 (SCSPRRu)(11a) and (SCSPSRu)-(11b)]. Only one enantiomeric pair of the hydride 9 is obtained from the chloro precursor 4 that bears sterically bulky substituents at the phosphorus centers. On the other hand, the optically pure trichiral complex 6 that bears sterically less bulky substituents at the phosphorus gives a mixture of two diastereomers (11a and 11b). Protonation of complex 7 using different acids (HX) gives a mixture of [(eta(5)- Cp)Ru(eta(2)-H-2){kappa(2)-P, P-(RO)(2)PN(Me)P(OR)(2))]X (12a) and [(eta(5)-Cp)Ru(H)(2){kappa(2)-P, P-(RO)(2)PN(Me)P(OR)(2)}]X (12b) of which 12a is the major product independent of the acid used; the dihydrogen nature of 12a is established by T, measurements and also by synthesizing the deuteride analogue 7-D followed by protonation to obtain the D-H isotopomer. Preliminary investigations on asymmetric transfer hydrogenation of 2-acetonaphthone in the presence of a series of chiral diphosphazane ligands show that diphosphazanes in which the phosphorus centers are strong pi-acceptor in character and bear sterically bulky substituents impart moderate levels of enantioselectivity. Attempts to identify the hydride intermediate involved in the asymmetric transfer hydrogenation by a model reaction suggests that a complex of the type, [Ru(H)(Cl){kappa(2)-P,P-X2PN(R)PY2)(solvent)(2)] could be the active species in this transformation. (c) 2007 Elsevier B.V. All rights reserved

Tetranuclear [{Ni(HL3)}{W(CN)8}]2 square: a case of antiferromagnetic {NiIIWV} interactions

A tetranuclear cyano-bridged [{Ni(HL3)}{W(CN)8}]2 compound in a square geometry was formed by self-assembling of {W(CN)8}3− and {NiL3}2+ (L3 = pentadentate ligand). The structure of the compound has been established by single crystal X-ray diffraction. The coordination sphere of the Ni ions is severely distorted with the macrocyclic ligand adopting a facial coordination with only four linkages to the metal center. The N atom of the pendant aminopropyl arm of L3 is no longer coordinated to the metal center but has undergone protonation during the assembling process. Magnetic measurements have revealed an unexpected antiferromagnetic behavior (J = −9 cm−1), which has been explained using a microscopic many-body electronic model Hamiltonian, based on DFT results. The many-body model is used to fit both the χMT versus T and the M versus H plots obtained from experiments

Tetranuclear [{Ni(HL<SUP>3</SUP>)}{W(CN)<SUB>8</SUB>}]<SUB>2</SUB> square: a case of antiferromagnetic {Ni<SUP>II</SUP>W<SUP>V</SUP>} interactions

A tetranuclear cyano-bridged [{Ni(HL3)}{W(CN)8}]2 compound in a square geometry was formed by self-assembling of {W(CN)8}3&#8722; and {NiL3}2+ (L3=pentadentate ligand). The structure of the compound has been established by single crystal X-ray diffraction. The coordination sphere of the Ni ions is severely distorted with the macrocyclic ligand adopting a facial coordination with only four linkages to the metal center. The N atom of the pendant aminopropyl arm of L3 is no longer coordinated to the metal center but has undergone protonation during the assembling process. Magnetic measurements have revealed an unexpected antiferromagnetic behavior (J=&#8722;9 cm&#8722;1), which has been explained using a microscopic many-body electronic model Hamiltonian, based on DFT results. The many-body model is used to fit both the XMT versus T and the M versus H plots obtained from experiments