Complexation of the triply-bonded dirhenium(II) complex Re(2)Cl(4)(mu-dppm)(2) (dppm = Ph(2)PCH(2)PPh(2)) by up to three acetylene molecules

The triply bonded dirhenium(II) synthons Re(2)X(4)(mu-dppm)(2) (X = Cl, Br; dppm = Ph(2)PCH(2)PPh(2)) react with acetylene at room temperature in CH(2)Cl(2) and acetone to afford the bis(acetylene) complexes Re(2)X(4)(mu-dppm)(2)(mu:eta(2),eta(2)-HCCH)(eta(2)-HCCH) (X = Cl (3), Br(4)). Compound 3 has been derivatized by reaction with RNC ligands in the presence of TlPF(6) to give unsymmetrical complexes of the type [Re(2)Cl(3)(mu-dppm)(2)(mu:eta(2),eta(2)-HCCH)(eta(2)-HCCH)(CNR)]PF(6) (R = Xyl (5), Mes (6), t-Bu (7)), in which the RCN ligand has displaced the chloride ligand cis to the eta(2)-HCCH ligand. The reaction of 3 with an additional 1 equiv of acetylene in the presence of TlPF(6) gives the symmetrical all-cis isomer of [Re(2)Cl(3)(mu-dppm)(2)(mu:eta(2),eta(2)-HCCH)(eta(2)-HCCH)(2)]PF(6) (8). The two terminal eta(2)-HCCH ligands in 8 are very labile and can be displaced by CO and XylNC to give the complexes [Re(2)Cl(3)(mu-dppm)(2)(mu:eta(2),eta(2)-HCCH)(L)(2)]Y (L = CO when Y = PF(6) (9); L = CO when Y = (PF(6))(0.5)/(H(2)PO(4))(0.5) (10); L = XylNC when Y = PF(6) (11)). These substitution reactions proceed with retention of the all-cis stereochemistry. Single-crystal X-ray structure determinations have been carried out on complexes 3, 5, 8, 10, and 11. In no instance have we found that the acetylene ligands undergo reductive coupling reactions.     

Reactions of [(eta(6)-arene)RuCl(2)](2) with Aromatic Phosphines Containing Methoxy Groups in 2,6-Positions

Reactions of [(eta(6)-arene)RuCl(2)](2) 1 (arene = p-cymene (a), 1,2,3,4-Me(4)C(6)H(2) (b), 1,2,3-Me(3)C(6)H(2) (c)) with tris(2,6-dimethoxyphenyl)phosphine (TDMPP) led to loss of two molecules of CH(3)Cl to give (eta(6)-arene)Ru[{2-O-C(6)H(3)-6-OMe}(2){C(6)H(3)(OMe)(2)-2,6}], 2a-c, which contains a trihapto ligand (eta(3)-P,O,O) derived from TDMPP, whereas the 1,3,5-Me(3)C(6)H(3) (1d), 1,2,3,5-Me(4)C(6)H(2) (1e), and C(6)Me(6) (1f) complexes did not react with TDMPP. The structures of 2a and 2b were confirmed by X-ray analyses: for 2a, a = 11.691(2) ?, b = 15.228(2) ?, c = 10.320(1) ?, alpha = 95.93(1) degrees, beta = 113.783(9) degrees, gamma = 83.86(1) degrees, triclinic, P&onemacr;, Z = 2, R = 0.051; for 2b, a = 17.79(2) ?, b = 15.43(1) ?, c = 20.93(1) ?, beta = 91.25(8) degrees, monoclinic, P2(1)/n, Z = 8, R = 0.056. Bis(2,6-dimethoxyphenyl)phenylphosphine (BDMPP) reacted with 1a, 1b, and 1d at room temperature to give (eta(6)-arene)RuCl[PPh(2-O-C(6)H(3)-6-OMe){C(6)H(3)(OMe)(2)-2,6}], 3a,b,d, which contains a dihapto (eta(2)-P,O) ligand derived from BDMPP by an X-ray analysis of 3a: a = 12.33(1) ?, b = 14.246(8) ?, c = 11.236(9) ?, alpha = 91.47(8) degrees, beta = 117.28(6) degrees, gamma = 111.70(6) degrees, triclinic, P&onemacr;, Z = 2, R = 0.040. A similar reaction with 1f recovered the starting materials, but that in refluxing MeCN produced [(eta(6)-C(6)Me(6))Ru[PPh(2-O-C(6)H(3)-6-OMe}(2)], 4f, containing a trihapto (eta(3)-P,O,O) ligand derived from BDMPP. Complex 1d reacted with BDMPP at reflux in MeCN/CH(2)Cl(2) and resulted in a loss of an arene ring to give a five-coordinate complex, Ru[eta(2)-P,O-PPh(2-O-C(6)H(3)-6-OMe){C(6)H(3)(OMe)(2)-2,6}](2)(MeCN), 5. Treatment of (2,6-dimethoxyphenyl)diphenylphosphine (MDMPP) with 1f gave (eta(6)-C(6)Me(6))RuCl[eta(2)-P,O-PPh(2)(2-O-C(6)H(3)-6-OMe)],6f, and that with 1b gave (eta(6)-1,2,3,4-Me(4)C(6)H(2))RuCl[eta(2)-P,O-PPh(2)(2-O-C(6)H(3)-6-OMe}], 6b, and (eta(6)-1,2,3,4-Me(4)C(6)H(2))RuCl(2)[eta(1)-P-PPh(2){C(6)H(3)(OMe)(2)-2,6}],7b. The phosphine ligand of 6b acted as a bidentate ligand derived from MDMPP: a = 8.074(4) ?, b = 16.816(3) ?, c = 18.916(4) ?, beta = 94.05(3) degrees, monoclinic, P2(1)/n, Z = 4, R = 0.051. Transformation of 7b to 6b readily occurred accompanying an elimination of MeCl. Reaction of 1a with MDMPP eliminated an arene ring to give the octahedral compound RuCl(2)[eta(2)-P,OMe-PPh(2){C(6)H(3)(MeO)(2)-2,6}](2), 8. An X-ray analysis of 8 showed that two MDMPP ligands were in a cis-position: a = 10.596(14) ?, b = 27.586(12) ?, c = 13.036(8) ?, beta = 108.17(7) degrees, monoclinic, P2(1)/n, Z = 4, R = 0.035.     

Monomeric Bis(eta(2)-alkyne)copper(I) and -silver(I) Halides, Pseudohalides, and Arenethiolates

The synthesis and characterization of the complexes [(eta(5)-C(5)H(4)SiMe(3))(2)Ti(C&tbd1;CSiMe(3))(2)]MX (M = Cu, X = OTf (2), SC(6)H(5) (4), SC(6)H(4)NMe(2)-2 (5), SC(6)H(4)CH(2)NMe(2)-2 (6), S-1-C(10)H(6)NMe(2)-8 (7), Cl (8), (N&tbd1;CMe)PF(6) (9); M = Ag, X = OTf (3)) are described. These complexes contain monomeric MX entities, which are eta(2)-bonded by both alkyne functionalities of the organometallic bis(alkyne) ligand [(eta(5)-C(5)H(4)SiMe(3))(2)Ti(C&tbd1;CSiMe(3))(2)] (1). The reactions of 2 with the Lewis bases N&tbd1;CPh and N&tbd1;CC(H)=C(H)C&tbd1;N afford the cationic complexes {[(eta(5)-C(5)H(4)SiMe(3))(2)Ti(C&tbd1;CSiMe(3))(2)]Cu(N&tbd1;CPh)}OTf (10) and {[(eta(5)-C(5)H(4)SiMe(3))(2)Ti(C&tbd1;CSiMe(3))(2)]Cu}(2)(N&tbd1;CC(H)=C(H)C&tbd1;N)(OTf)(2) (11), respectively. The X-ray structures of 2, 3, and 6 have been determined. Crystals of 2 are monoclinic, space group P2(1)/c, with a = 12.8547(7) ?, b = 21.340(2) ?, c = 18.279(1) ?, beta = 133.623(5) degrees, V= 3629.7(5) ?(3), Z = 4, and final R = 0.047 for 5531 reflections with I >/= 2.5sigma(I) and 400 variables. The silver triflate complex 3 is isostructural, but not isomorphous, with the corresponding copper complex 2, and crystals of 3 are monoclinic, space group P2(1)/c, with a = 13.384(3) ?, b = 24.55(1) ?, c = 13.506(3) ?, beta = 119.21(2) degrees, V = 3873(2) ?(3), Z = 4, and final R = 0.038 for 3578 reflections with F >/= 4sigma(F) and 403 variables. Crystals of the copper arenethiolate complex 6 are triclinic, space group P&onemacr;, with a = 11.277(3) ?, b = 12.991(6) ?, c = 15.390(6) ?, alpha = 65.17(4) degrees, beta = 78.91(3) degrees, gamma = 84.78(3) degrees, V = 2008(2) ?(3), Z = 2, and final R = 0.079 for 6022 reflections and 388 variables. Complexes 2-11 all contain a monomeric bis(eta(2)-alkyne)M(eta(1)-X) unit (M = Cu, Ag) in which the group 11 metal atom is trigonally coordinated by the chelating bis(eta(2)-alkyne) entity Ti(C&tbd1;CSiMe(3))(2) and an eta(1)-bonded monoanionic ligand X. The copper arenethiolate complexes 4-7 are fluxional in solution.     

Ammonolysis of mono(pentamethylcyclopentadienyl) titanium(IV) derivatives

Ammonolyses of mono(pentamethylcyclopentadienyl) titanium(IV) derivatives [Ti(eta5-C5Me5)X3] (X = NMe2, Me, Cl) have been carried out in solution to give polynuclear nitrido complexes. Reaction of the tris(dimethylamido) derivative [Ti(eta5-C5Me5)(NMe2)3] with excess of ammonia at 80-100 degrees C gives the cubane complex [[Ti(eta5-C5Me5)]4(mu3-N)4] (1). Treatment of the trimethyl derivative [Ti(eta5-C5Me5)Me3] with NH3 at room temperature leads to the trinuclear imido-nitrido complex [[Ti(eta/5-CsMes)(mu-NH)]3(mu3-N)] (2) via the intermediate [[Ti(eta5-C5Me5)Me]2(mu-NH)2] (3). The analogous reaction of [Ti(eta5-C5Me5)Me3] with 2,4,6-trimethylaniline (ArNH2) gives the dinuclear imido complex [[Ti(eta5-C5Me5)Me])2(mu-NAr)2] (4) which reacts with ammonia to afford [[Ti(eta5-C5Me5)(NH2)]2(mu-NAr)2] (5). Complex 2 has been used, by treatments with the tris(dimethylamido) derivatives [Ti(eta5-C5H5-nRn)(NMe2)3], as precursor of the cubane nitrido systems [[Ti4(eta5-C5Me5)3(eta5-C5H5-nRn)](mu3-N)4] [R = Me n = 5 (1), R = H n = 0 (6), R = SiMe3 n = 1 (7), R = Me n = 1 (8)] via dimethylamine elimination. Reaction of [Ti(eta5-C5Me5)Cl3] or [Ti(eta5-C5Me5)(NMe2)Cl2] with excess of ammonia at room temperature gives the dinuclear complex [[Ti2(eta5-C5Me5)2Cl3(NH3)](mu-N)] (9) where an intramolecular hydrogen bonding and a nonlineal nitrido ligand bridge the "Ti(eta5-C5Me5)Cl(NH3)" and "Ti(eta5-C5Me5)Cl2" moieties. The molecular structures of [[Ti(eta5-C5Me5)Me]2 (mu-NAr)2] (4) and [[Ti2(eta5-C5Me5)2Cl3(NH3)](mu-N)] (9) have been determined by X-ray crystallographic studies. Density functional theory calculations also have been conducted on complex 9 to confirm the existence of an intramolecular N-H...Cl hydrogen bond and to evaluate different aspects of its molecular disposition.     

Photochemical Synthesis of (eta(6)-Arene)chromium Hydrido Stannyl and (eta(6)-Arene)chromium Bis(stannyl) Complexes

Photolysis of (eta(6)-arene)Cr(CO)(3) complexes and HSnPh(3) in aromatic solvents at room temperature has led to two classes of complexes: hydrido stannyl compounds containing the eta(2)-H-SnPh(3) ligand and bis(stannyl) compounds containing two SnPh(3) ligands. The ratio between the two complexes simultaneously produced depends on the choice of the arene. Complexes with different arenes (mesitylene, toluene, benzene, fluorobenzene, and difluorobenzene) have been obtained and characterized including X-ray structures for (eta(6)-C(6)H(3)(CH(3))(3))Cr(CO)(2)(H)(SnPh(3)) (1a), (eta(6)-C(6)H(3)(CH(3))(3))Cr(CO)(2)(SnPh(3))(2) (1b), (eta(6)-C(6)H(5)F)Cr(CO)(2)(SnPh(3))(2) (4b), and (eta(6)-C(6)H(4)F(2))Cr(CO)(2)(SnPh(3))(2) (5b). X-ray crystallography of the last three compounds has given the following results: 1b, monoclinic, space group P2(1)/c (No. 14), a = 13.905(4) ?, b = 18.499(2) ?, c = 17.708(2) ?, Z = 4, V = 4285(1) ?(3); 4b, orthorhombic, space group Pca2(1) (No. 29), a = 16.717(2) ?, b = 18.453(2) ?, c = 25.766(2) ?, Z = 8, V = 7948(2) ?(3); 5b, monoclinic, space group P2(1)/c (No. 14), a = 13.756(2) ?, b = 18.560(2) ?, c = 17.159(2) ?, Z = 4, V = 4372(2) ?(3). The relatively high J((119)Sn-Cr-H) and J((117)Sn-Cr-H) values as well as the X-ray structural data provide evidence for the existence of three-center two-electron bonds in the hydrido stannyl complexes. The (1)H NMR data of the complexes are compared with chromium-arene bond distances, and a sensible trend is observed and discussed.     

Ruthenium(II) and ruthenium(IV) complexes containing kappa1-P-, kappa2-P,O-, and kappa3-P,N,O-iminophosphorane-phosphine ligands Ph2PCH2P[=NP(=O)(OR)2]Ph2 (R = Et,Ph): synthesis,reactivity, theoretical studies,and catalytic activity in transfer hydrogenation of cyclohexanone

[(Ru(eta(6)-p-cymene)(mu-Cl)Cl)(2)] and [(Ru(eta(3):eta(3)-C(10)H(16))(mu-Cl)Cl)(2)] react with Ph(2)PCH(2)P[=NP(=O)(OR)(2)]Ph(2) (R = Et (1a), Ph (1b)) affording complexes [Ru(eta(6)-p-cymene)Cl(2)(kappa(1)-P-Ph(2)PCH(2)P[=NP(=O)(OR)(2)]Ph(2))] (R = Et (2a), Ph (2b)) and [Ru(eta(3):eta(3)-C(10)H(16))Cl(2)(kappa(1)-P-Ph(2)PCH(2)P[=NP(=O)(OR)(2)]Ph(2))] (R = Et (6a), Ph (6b)). While treatment of 2a with 1 equiv of AgSbF(6) yields a mixture of [Ru(eta(6)-p-cymene)Cl(kappa(2)-P,O-Ph(2)PCH(2)P[=NP(=O)(OEt)(2)]Ph(2))][SbF(6)] (3a) and [Ru(eta(6)-p-cymene)Cl(kappa(2)-P,N-Ph(2)PCH(2)P[=NP(=O)(OEt)(2)]Ph(2))][SbF(6)] (4a), [Ru(eta(6)-p-cymene)Cl(kappa(2)-P,O-Ph(2)PCH(2)P[=NP(=O)(OPh)(2)]Ph(2))][SbF(6)] (3b) and [Ru(eta(3):eta(3)-C(10)H(16))Cl(kappa(2)-P,O-Ph(2)PCH(2)P[=NP(=O)(OR)(2)]Ph(2))][SbF(6)] (R = Et (7a), Ph (7b)) are selectively formed from 2b and 6a,b. Complexes [Ru(eta(6)-p-cymene)(kappa(3)-P,N,O-Ph(2)PCH(2)P[=NP(=O)(OR)(2)]Ph(2))][SbF(6)](2) (R = Et (5a), Ph (5b)) and [Ru(eta(3):eta(3)-C(10)H(16))(kappa(3)-P,N,O-Ph(2)PCH(2)P[=NP(=O)(OR)(2)]Ph(2))][SbF(6)](2) (R = Et (8a), Ph (8b)) have been prepared using 2 equiv of AgSbF(6). The reactivity of 3-5a,b has been explored allowing the synthesis of [Ru(eta(6)-p-cymene)X(2)(kappa(1)-P-Ph(2)PCH(2)P[=NP(=O)(OR)(2)]Ph(2))] (R = Et, Ph; X = Br, I, N(3), NCO (9-12a,b)). The catalytic activity of 2-8a,b in transfer hydrogenation of cyclohexanone, as well as theoretical calculations on the models [Ru(eta(6)-C(6)H(6))Cl(kappa(2)-P,N-H(2)PCH(2)P[=NP(=O)(OH)(2)]H(2))]+ and [Ru(eta(6)-C(6)H(6))Cl(kappa(2)-P,O-H(2)PCH(2)P[=NP(=O)(OH)(2)]H(2))]+, has been also studied.     

Preparation and characterization of diarylphosphazene and diarylphosphinohydrazide complexes of titanium, tungsten and ruthenium and phosphorylketimido complexes of rhenium

Reaction of the proligand Ph2PN(SiMe3)2 (L1) with WCl6 gives the oligomeric phosphazene complex [WCl4(NPPh2)]n, 1 and subsequent reaction with PMe2Ph or NBu4Cl gives [WCl4(NPPh2)(PMe2Ph)] (2) or [WCl5(NPPh2)][NBu4] (3), respectively. DF calculations on [WCl5(NPPh2)][NBu4] show a W=N double bond (1.756 A) and a P-N bond distance of 1.701 A, which combined with the geometry about the P atom suggests, there is no P-N multiple bonding. Reaction of L1 with [ReOX3(PPh3)2] in MeCN (X = Cl or Br) gives [ReX2(NC(CH3)P(O)Ph2)(MeCN)(PPh3)](X = Cl, 4, X = Br, 5) which contains the new phosphorylketimido ligand. It is bound to the rhenium centre with a virtually linear Re-N-C arrangement (Re-N-C angle = 176.6 degrees, when X = Cl) and there is multiple bonding between Re and N (Re-N = 1.809(7) A when X = Cl). The proligand Ph2PNHNMe2(L2H) reacts with [(C5H5)TiCl3] to give [(C5H5)TiCl2(Me2NNPPh2)] (6). An X-ray crystal structure of the complex shows the ligand (L2) is bound by both nitrogen atoms. Reaction of the proligands Ph2PNHNR2[R2 = Me2 (L2H), -(CH2CH2)2NCH3 (L3H), (CH2CH2)2CH2 (L4H)] with [{RuCl(mu-Cl)(eta6-p-MeC6H4iPr)}2] gave [RuCl2(eta6-p-MeC6H4iPr)L] {L = L2H (7), L3H (8), L4H (9)}. The X-ray crystal structures of 7-9 confirmed that the phosphinohydrazine ligand is neutral and bound via the phosphorus only. Reaction of complexes 7-9 with AgBF4 resulted in chloride ion abstraction and the formation of the cationic species [RuCl(6-p-MeC6H4iPr)(L)]+ BF4- {(L = L2H (10), L3H (11), L4H (12)}. Finally, reaction of complex 6 with [{RuCl(mu-Cl)(eta6-p-MeC6H4iPr)}2] gave the binuclear species [(eta6-p-MeC6H4iPr)Cl2Ru(mu2,eta3-Ph2PNNMe2)TiCl2(C5H5)], 13.     

Various forms of linear dipyridyls in discrete rectangles, dinuclear rods, and one-dimensional networks containing (eta5-pentamethylcyclopentadienyl)rhodium(III)

[Cp*Rh(eta1-NO3)(eta2-NO3)] (1) reacted with pyrazine (pyz) to give a dinuclear complex [Cp*Rh(eta1-NO3)(mu-pyz)(0.5)]2.CH2Cl2(3.CH2Cl2). Tetranuclear rectangles of the type [Cp*Rh(eta1,mu-X)(mu-L)(0.5)]4(OTf)4(4a: X = N3, L = bpy; 4b: X = N3, L = bpe; 4c: X = NCO, L = bpy) were prepared from [Cp*Rh(H2O)3](OTf)2 (2), a pseudo-halide (Me3SiN3 or Me3SiNCO), and a linear dipyridyl [4,4'-bipyridine (bpy) or trans-1,2-bis(4-pyridyl)ethylene (bpe)] by self-assembly through one-pot synthesis at room temperature. Treating complex with NH4SCN and dipyridyl led to the formation of dinuclear rods, [Cp*Rh(eta1-SCN)3]2(LH2) (5a: L = bpy; 5b: L = bpe), in which two Cp*Rh(eta1-SCN)3 units are connected by the diprotonated dipyridyl (LH2(2+)) through N(+)-H...N hydrogen bonds. Reactions of complex 2 with 1-(trimethylsilyl)imidazole (TMSIm) and dipyridyl (bpy or bpe) also produced another family of dinuclear rods [Cp*Rh(ImH)3]2.L (6a: L = bpy; 6b: L = bpe). Treating 1 and 2 with TMSIm and NH4SCN (in the absence of dipyridyl) generated a 1-D chain [Cp*Rh(ImH)3](NO3)2 (7) and a 1-D helix [Cp*Rh(eta1-SCN)2(eta1-SHCN)].H2O (8.H2O), respectively. The structures of complexes 3.CH2Cl2, 4a.H2O, 4c.2H2O, 5b, 6a, 7 and 8.H2O were determined by X-ray diffraction.     

Light-induced metastable linkage isomers of ruthenium sulfur dioxide complexes

The irradiation of ruthenium-sulfur dioxide complexes of general formula trans-[Ru(II)(NH(3))(4)(SO(2))X]Y with laser light at low temperature results in linkage isomerization of SO(2), starting with eta(1)-planar S-bound to eta(2)-side S,O-bound SO(2). The solid-state photoreaction proceeds with retention of sample crystallinity. Following work on trans-[Ru(NH(3))(4)Cl(eta(1)-SO(2))]Cl and trans-[Ru(NH(3))(4)(H(2)O)(eta(1)-SO2)](C(6)H(5)SO(3))(2) (Kovalevsky, A. Y.; Bagley, K. A.; Coppens, P. J. Am. Chem. Soc. 2002, 124, 9241-9248), we describe photocrystallographic, IR, DSC, and theoretical studies of trans-[Ru(II)(NH(3))(4)(SO(2))X]Y complexes with (X = Cl(-), H(2)O, or CF(3)COO(-) (TFA(-))) and a number of different counterions (Y = Cl(-), C(6)H(5)SO(3)(-), Tos(-), or TFA(-)). Low temperature IR experiments indicate the frequency of the asymmetric and symmetric stretching vibrations of the Ru-coordinated SO(2) to be downshifted by about 100 and 165 cm(-1), respectively. Variation of the trans-to-SO(2) ligand and the counterion increases the MS2 decay temperature from 230 K (trans-[Ru(II)(NH(3))(4)(SO(2))Cl]Cl) to 276 K (trans-[Ru(II)(NH(3))(4)(SO(2))(H(2)O)](Tos)(2)). The stability of the MS2 state correlates with increasing sigma-donating ability of the trans ligand and the size of the counterion. Quantum chemical DFT calculations indicate the existence of a third eta(1)-O-bound (MS1) isomer, the two metastable states being 0.1-0.6 eV above the energy of the ground-state complex.     

Synthesis and structure of organic-soluble binuclear molecular phosphonates of tantalum,molybdenum, and tungsten

The reaction of (eta 5-C5Me5)TaMe4 with tert-butylphosphonic acid leads to the formation of a mixture of compounds: [[(eta 5-C5Me5)TaMe][t-BuP(O)(OH)][t-BuP(O)(OH)2]]2(t-BuPO3)2 (1) and [[(eta 5-C5Me5)Ta][t-BuP(O)(OH)2]]2(t-BuPO3)2(mu-O)2 (2). Compound 2 was also obtained by recrystallization of 1 from a THF/hexane mixture. Reaction of (eta 5-C5Me5)MCl4 (M = Mo, W) with PhP(O)(OH)2 yields the binuclear phosphonates [[(eta 5-C5Me5)M][PhP(O)(OH)2]]2(PhPO3)2(mu-O)2 (M = Mo (3); M = W (4)). Compounds 2.THF and 3(.)2.5THF were characterized by single-crystal X-ray studies. The tantalum and molybdenum phosphonates 2.THF and 3(.)2.5THF have different structures as compared to those of the previously reported titanophosphonate cages.     

Synthesis and Electrochemistry of Heterobimetallic Ruthenium/Platinum and Molybdenum/Platinum Complexes

As starting materials for heterobimetallic complexes, [RuCp(PPh(3))CO(PPh(2)H)]PF(6) and [RuCp(PPh(3))CO(eta(1)-dppm)]PF(6) were prepared from RuCp(PPh(3))(CO)Cl. In the course of preparing [RuCp(eta(2)-dppm)(eta(1)-dppm)]Cl from RuCp(Ph(3)P)(eta(1)-dppm)Cl, the new monomer RuCpCl(eta(1)-dppm)(2) was isolated. The uncommon coordination mode of the two monodentate bis(phosphines) was confirmed by X-ray crystallography [a = 11.490(1) ?, b = 14.869(2) ?, c = 15.447(2) ?, alpha = 84.63(1) degrees, beta = 70.55(1) degrees, gamma = 72.92(1) degrees, V = 2378.7(5) ?(3), d(calc) = 1.355 g cm(-)(3) (298 K), triclinic, P&onemacr;, Z = 2]. The dppm-bridged bimetallic complexes RuCp(PPh(3))Cl(&mgr;-dppm)PtCl(2), RuCpCl(&mgr;-dppm)(2)PtCl(2), and [RuCp(PPh(3))CO(&mgr;-dppm)PtCl(2)]PF(6) each exhibit electrochemistry consistent with varying degrees of metal-metal interaction. The cationic heterobimetallic complexes [Mo(CO)(3)(&mgr;-dppm)(2)Pt(H)]PF(6) and [MoCp(CO)(2)(&mgr;-PPh(2))(&mgr;-H)Pt(PPh(3))(MeCN)]PF(6) were prepared by chloride abstraction from the corresponding neutral bimetallic species and show electrochemical behavior similar to the analogous Ru/Pt complexes.     

Assembly of Carbohydrates on a Nickel(II) Center by Utilizing N-Glycosidic Bond Formation with Tris(2-aminoethyl)amine (tren). Syntheses and Characterization of [Ni{N-(aldosyl)-tren}(H(2)O)](2+), [Ni{N,N'-bis(aldosyl)-tren}](2+) and [Ni{N,N',N"-tris(aldosyl)-tren}](2+)

Reactions of [Ni(tren)(H(2)O)(2)]X(2) (tren = tris(2-aminoethyl)amine; X = Cl (1a), Br (1b); X(2) = SO(4) (1c)) with mannose-type aldoses, having a 2,3-cis configuration (D-mannose and L-rhamnose), afforded {bis(N-aldosyl-2-aminoethyl)(2-aminoethyl)amine}nickel(II) complexes, [Ni(N,N'-(aldosyl)(2)-tren)]X(2) (aldosyl = D-mannosyl, X = Cl (2a), Br (2b), X(2) = SO(4) (2c); aldosyl = L-rhamnosyl, X(2) = SO(4) (3c)). The structure of 1c was confirmed by X-ray crystallography to be a mononuclear [Ni(II)N(4)O(2)] complex with the tren acting as a tetradentate ligand (1c.2H(2)O: orthorhombic, Pbca, a = 15.988(2) ?, b = 18.826(4) ?, c = 10.359(4) ?, V = 3118 ?(3), Z = 8, R = 0.047, and R(w) = 0.042). Complexes 2a,c and 3c were characterized by X-ray analyses to have a mononuclear octahedral Ni(II) structure ligated by a hexadentate N-glycoside ligand, bis(N-aldosyl-2-aminoethyl)(2-aminoethyl)amine (2a.CH(3)OH: orthorhombic, P2(1)2(1)2(1), a = 16.005(3) ?, b = 20.095(4) ?, c = 8.361(1) ?, V = 2689 ?(3), Z = 4, R = 0.040, and R(w) = 0.027. 2c.3CH(3)OH: orthorhombic, P2(1)2(1)2(1), a = 14.93(2) ?, b = 21.823(8) ?, c = 9.746(2) ?, V = 3176 ?(3), Z = 4, R = 0.075, and R(w) = 0.080. 3c.3CH(3)OH: orthorhombic, P2(1)2(1)2(1), a = 14.560(4) ?, b = 21.694(5) ?, c = 9.786(2) ?, V = 3091 ?(3), Z = 4, R = 0.072, and R(w) = 0.079). The sugar part of the complex involves novel intramolecular sugar-sugar hydrogen bondings around the metal center. The similar reaction with D-glucose, D-glucosamine, and D-galactosamine, having a 2,3-trans configuration, resulted in the formation of a mono(sugar) complex, [Ni(N-(aldosyl)-tren)(H(2)O)(2)]Cl(2) (aldosyl = D-glucosyl (4b), 2-amino-2-deoxy-D-glucosyl (5a), and 2-amino-2-deoxy-D-galactosyl (5b)), instead of a bis(sugar) complex. The hydrogen bondings between the sugar moieties as observed in 2 and 3 should be responsible for the assembly of two sugar molecules on the metal center. Reactions of tris(N-aldosyl-2-aminoethyl)amine with nickel(II) salts gave the tris(sugar) complexes, [Ni(N,N',N"-(aldosyl)(3)-tren)]X(2) (aldosyl = D-mannosyl, X = Cl (6a), Br (6b); L-rhamnosyl, X = Cl (7a), Br (7b); D-glucosyl, X = Cl (9); maltosyl, X = Br (10); and melibiosyl, X = Br (11)), which were assumed to have a shuttle-type C(3) symmetrical structure with Delta helical configuration for D-type aldoses on the basis of circular dichroism and (13)C NMR spectra. When tris(N-rhamnosyl)-tren was reacted with NiSO(4).6H(2)O at low temperature, a labile neutral complex, [Ni(N,N',N"-(L-rhamnosyl)(3)-tren)(SO(4))] (8), was successfully isolated and characterized by X-ray crystallography, in which three sugar moieties are anchored only at the N atom of the C-1 position (8.3CH(3)OH.H(2)O: orthorhombic, P2(1)2(1)2(1), a = 16.035(4) ?, b = 16.670(7) ?, c = 15.38(1) ?, V = 4111 ?(3), Z = 4, R = 0.084, and R(w) = 0.068). Complex 8 could be regarded as an intermediate species toward the C(3) symmetrical tris(sugar) complexes 7, and in fact, it was readily transformed to 7b by an action of BaBr(2).     

Linear Trinuclear Pt.Mo-Mo Complexes [Mo(2)PtX(2)(pyphos)(2)(O(2)CR)(2)](2) (X = Cl, Br, I; R = CH(3), C(CH(3))(3); pyphos = 6-(Diphenylphosphino)-2-pyridonate) with an Axial Interaction between the Quadruply Bonded Mo(2) Moiety and the Platinum Atom

An example of a direct axial interaction of a platinum(II) atom with a Mo(2) core through a uniquely designed tridentate ligand 6-(diphenylphosphino)-2-pyridonate (abbreviated as pyphos) is described. Treatment of PtX(2)(pyphosH)(2) (2a, X = Cl; 2b, X = Br; 2c, X = I) with a 1:1 mixture of Mo(2)(O(2)CCH(3))(4) and [Mo(2)(O(2)CCH(3))(2)(NCCH(3))(6)](2+) (3a) in dichloromethane afforded the linear trinuclear complexes [Mo(2)PtX(2)(pyphos)(2)(O(2)CCH(3))(2)](2) (4a, X = Cl; 4b, X = Br; 4c, X = I). The reaction of [Mo(2)(O(2)CCMe(3))(2)(NCCH(3))(4)](2+) (3b) with 2a-c in dichloromethane afforded the corresponding pivalato complexes [Mo(2)PtX(2)(pyphos)(2)(O(2)CCMe(3))(2)](2) (5a, X = Cl; 5b, X = Br; 5c, X = I), whose bonding nature is discussed on the basis of the data from Raman and electronic spectra as well as cyclic voltammograms. The linear trinuclear structures in 4b and 5a-c were confirmed by NMR studies and X-ray analyses: 4b, monoclinic, space group C2/c, a = 34.733(4) ?, b = 17.81(1) ?, c = 22.530(5) ?, beta = 124.444(8) degrees, V = 11498(5) ?(3), Z = 8, R = 0.060 for 8659 reflections with I > 3sigma(I) and 588 parameters; 5a, triclinic, space group P&onemacr;, a = 13.541(3) ?, b = 17.029(3) ?, c = 12.896(3) ?, alpha = 101.20(2) degrees, beta = 117.00(1) degrees, gamma = 85.47(2) degrees, V = 2599(1) ?(3), Z = 2, R = 0.050 for 8148 reflections with I > 3sigma(I) and 604 parameters; 5b, triclinic, space group P&onemacr;, a = 12.211(2) ?, b = 20.859(3) ?, c = 10.478(2) ?, alpha = 98.88(1) degrees, beta = 112.55(2) degrees, gamma = 84.56(1) degrees, V = 2433.3(8) ?(3), Z = 2, R = 0.042 for 8935 reflections with I > 3sigma(I) and 560 parameters; 5c, monoclinic, space group P2(1)/n, a = 13.359(4) ?, b = 19.686(3) ?, c = 20.392(4) ?, beta = 107.92(2) degrees, V = 5101(2) ?(3), Z = 4, R = 0.039 for 8432 reflections with I > 3sigma(I) and 560 parameters.     

Preparation of mononuclear and dinuclear Rh hydrotris(pyrazolyl)borato complexes containing arenethiolato ligands and conversion of the mononuclear complexes into dinuclear Rh-Rh and Rh-Ir complexes with bridging arenethiolato ligands

Reactions of [Tp*Rh(coe)(MeCN)](; Tp*= HB(3,5-dimethylpyrazol-1-yl)(3); coe = cyclooctene) with one equiv. of the organic disulfides, PhSSPh, TolSSTol (Tol = 4-MeC(6)H(4)), PySSPy (Py = 2-pyridyl), and tetraethylthiuram disulfide in THF at room temperature afforded the mononuclear Rh(III) complexes [Tp*Rh(SPh)(2)(MeCN)](3a), [Tp*Rh(STol)(2)(MeCN)](3b), [Tp*Rh(eta(2)-SPy)(eta(1)-SPy)](6), and [Tp*Rh(eta(2)-S(2)CNEt(2))(eta(1)-S(2)CNEt(2))](7), respectively, via the oxidative addition of the organic disulfides to the Rh(I) center in 1. For the Tp analogue [TpRh(coe)(MeCN)](2, Tp = HB(pyrazol-1-yl)(3)), the reaction with TolSSTol proceeded similarly to give the bis(thiolato) complex [TpRh(STol)(2)(MeCN)](4) as a major product but the dinuclear complex [[TpRh(STol)](2)(micro-STol)(2)](5) was also obtained in low yield. Complex 3 was treated further with the Rh(III) or Ir(III) complexes [(Cp*MCl)(2)(micro-Cl)(2)](Cp*=eta(5)-C(5)Me(5)) in THF at room temperature, yielding the thiolato-bridged dinuclear complexes [Tp*RhCl(micro-SPh)(2)MCp*Cl](8a: M = Rh, 8b: M = Ir). Dirhodium complex [TpRhCl(micro-STol)(2)RhCp*Cl](9) was obtained similarly from 4 and [(Cp*RhCl)(2)(micro-Cl)(2)]. Anion metathesis of 8a proceeds only at the Rh atom with the Cp* ligand to yield [Tp*RhCl(micro-SPh)(2)RhCp*(MeCN)][PF(6)](10), when treated with excess KPF(6) in CH(2)Cl(2)-MeCN. The X-ray analyses have been undertaken to determine the detailed structures of 3b, 4, 5, 6, 7, 8a, 9, and 10.     

Synthesis and reactivity of iridium complexes with pyridine and piperidine ligands: models for hydrodenitrogenation

The complexes [Ir(H)2(eta1-N-L)2(PPh3)2]PF6, L = py (1), iQ (2) and pip (3) (py = pyridine, iQ = isoquinoline, pip = piperidine) have been synthesized in high yields by hydrogenation of [Ir(cod)(PPh3)2]PF6 in the presence of the appropriate nitrogen compound. When hydrogen is bubbled through 1,2-dichloroethane solutions of 1 or 2, two new species were formed in each case by C-Cl bond activation of the solvent, Ir(H)2Cl(eta1-N-L)(PPh3)2 (L = py, 4; iQ, 5) and IrH(Cl)2(eta1-N-L)(PPh3)2 (L = py, 6; iQ, 7). Reaction of 3 with py or iQ yielded complexes 1 and 2, respectively, while under a slow stream of carbon monoxide the complex [Ir(H)2(eta1-N-pip)(CO)(PPh3)2]PF6 (8) was produced. Complex 3 also reacts with halide and 4-bromothiophenolate anions leading to the corresponding neutral species Ir(H)2(X)(eta1-N-pip)(PPh3)2, X = Cl (9), I (10) and 4-BrC6H4S (11), or with [MoS4]2- to yield the hetero-bimetallic complex [Ir(H)(PPh3)2(mu-S)2MoS2]- (13). All the new complexes were characterized by analytical and spectroscopic methods. The X-ray structures of , 2 and 8 consist of distorted octahedra with a mutually cis disposition of the two hydrides and mutually trans phosphines. Complexes 1, 2 and 3 and their derivatives are of interest as models for the chemisorption step in hydrodenitrogenation reactions on solid catalysts.     

A New Type of Heterobimetallic Compound Containing Tungstenocene: Synthesis, Reactivity, NMR, and Stereochemical Studies

Reaction of [PPh(2)M(CO)(5)]Li salts (M = Cr or W) toward tungstenocene dichloride occurs via a cyclopentadienyl ring substitution and yields the corresponding binuclear compounds (eta(5)-C(5)H(5))[eta(5)-C(5)H(4)PPh(2)M(CO)(5)]W(H)Cl, 2. They react with LiAlH(4) to give the corresponding dihydride complexes (eta(5)-C(5)H(5))[eta(5)-C(5)H(4)PPh(2)M(CO)(5)]WH(2), 3. These species have been proven to be photosensitive leading to the cyclic heterobimetallic (eta(5)-C(5)H(5))[eta(5)-C(5)H(4)PPh(2)M(CO)(4)]W(&mgr;-H)H compounds, 4; analytical data and spectroscopic measurements on complexes 4 indicate that a hydride group functions as a bridging ligand. Crystals of 4a (M = Cr) were obtained as red needles, grown from toluene solution. An isotropic refinement of only 1243 data (F > 5sigma(F)) from a low resolution data set (3707 data, d(min) = 0.9 ?) indicated significant systematic error. Thus it was possible only to ascertain that the connectivity of the non-hydrogen atoms is not inconsistent with the model proposed from solution NMR and that the Cr.W separation of 3.30 ? precludes a direct Cr-W bond. 4a crystallizes in space group Pbca(No. 61), with a = 19.693(8) ?, b = 20.34(1) ?, c = 11.695(5) ?, V = 46823 ?(3), and Z = 8. Further information on this preliminary structure determination is provided in the Supporting Information. These reactions have been investigated with stereochemical factors in mind using the ring substituted tungtenocene complex (eta(5)-C(5)H(4)Me)(2)WCl(2); the 1-3 regioselectivity of the ring disubstitution reaction is proposed on the basis of (1)H NMR experiments. The temperature dependent relaxation time measured between 295 and 213 K by the inversion recovery method makes it possible to determine a proton-proton distance between the two H ligands of 2.0 ? in 4'a.     

Reactions of the dirhenium(II) complex Re2Cl4(mu-dppm)2 with pyridinecarboxylic acids. Examples of bidentate O,O versus N,O coordination and tridentate O,N,O coordination and structural isomers that contain the pyridine-2,6-dicarboxylate ligand

Pyridine-2-carboxylic acid, pyridine-2,3-dicarboxylic acid, and pyridine-2,4-dicarboxylic acid or their [(Ph(3)P)(2)N](+) salts react with the triply bonded dirhenium(II) complex Re(2)Cl(4)(mu-dppm)(2) (dppm = Ph(2)PCH(2)PPh(2)) in refluxing ethanol to afford unsymmetrical substitution products of the type Re(2)(eta(2)-N,O)Cl(3)(mu-dppm)(2), where N,O represents a chelating pyridine-2-carboxylate ligand (N,O = O(2)C-2-C(5)H(4)N (1), O(2)C-2-C(5)H(3)N(-3-CO(2)Et) (3), or O(2)C-2-C(5)H(3)N(-4-CO(2)H) (4)). The carboxylate groups in the 3- and 4- positions are not bound to the metal centers; in the case of 3 this group undergoes esterification in the refluxing ethanol solvent. Structure determinations have shown that 1, 3, and 4 possess similar structures in which there is an axial Re-O (carboxylate) bond (collinear with the Re(triple bond)Re bond) and the mu-dppm ligands are bound in a trans,cis fashion to the two Re atoms which have the ligand atom arrangement [P(2)NOClReReCl(2)P(2)]. The tridentate dianionic pyridine-2,6-dicarboxylate ligand (dipic) reacts with Re(2)Cl(4)(mu-dppm)(2) in ethanol at room temperature to give a compound Re(2)(dipic)Cl(2)(mu-dppm)(2) (6) in which the dipic ligand is bound in a symmetrical eta(3)-(O,N,O) fashion to one Re atom, with the N atom in an axial position (collinear with the Re(triple bond)Re bond) and with preservation of the same trans,trans coordination of the mu-dppm ligands that is present in Re(2)Cl(4)(mu-dppm)(2). Under reflux conditions, this kinetic product isomerizes to the thermodynamically favored isomer 5 with an unsymmetrical structure in which the dipic ligand chelates to one Re atom (as in 1, 3, and 4) and uses its other carboxylate group to bridge to the second Re atom. The isomerization of 6 to 5, which also results in a change in the coordination of the pair of mu-dppm ligand to trans,cis, is believed to occur by a partial "merry-go-round" process, a mechanism that probably explains the structures of the thermodynamic products 1, 3, and 4. The reaction of Re(2)Cl(4)(mu-dppm)(2) with pyridine-3-carboxylate gives the trans isomer of Re(2)(mu:eta(2)-O(2)C-3-C(5)H(4)N)(2)Cl(2)(mu-dppm)(2) (2) in which a pair of carboxylate bridges are present and the pyridine N atom is not coordinated. Single-crystal X-ray structural details are reported for 1-6.     

Synthesis,molecular structure,and C-C coupling reactions of carbeneruthenium(II) complexes with C5H5Ru(=CRR') and C5Me5Ru(=CRR') as molecular units

The ethene derivatives [(eta(5)-C(5)R(5))RuX(C(2)H(4))(PPh(3))] with R=H and Me, which have been prepared from the eta(3)-allylic compounds [(eta(5)-C(5)R(5))Ru(eta(3)-2-MeC(3)H(4))(PPh(3))] (1, 2) and acids HX under an ethene atmosphere, are excellent starting materials for the synthesis of a series of new halfsandwich-type ruthenium(II) complexes. The olefinic ligand is replaced not only by CO and pyridine, but also by internal and terminal alkynes to give (for X=Cl) alkyne, vinylidene, and allene compounds of the general composition [(eta(5)-C(5)R(5))RuCl(L)(PPh(3))] with L=C(2)(CO(2)Me)(2), Me(3)SiC(2)CO(2)Et, C=CHCO(2)R, and C(3)H(4). The allenylidene complex [(eta(5)-C(5)H(5))RuCl(=C=C=CPh(2))(PPh(3))] is directly accessible from 1 (R=H) in two steps with the propargylic alcohol HC triple bond CC(OH)Ph(2) as the precursor. The reactions of the ethene derivatives [(eta(5)-C(5)H(5))RuX(C(2)H(4))(PPh(3))] (X=Cl, CF(3)CO(2)) with diazo compounds RR'CN(2) yield the corresponding carbene complexes [(eta(5)-C(5)R(5))RuX(=CRR')(PPh(3))], while with ethyl diazoacetate (for X=Cl) the diethyl maleate compound [(eta(5)-C(5)H(5))RuCl[eta(2)-Z-C(2)H(2)(CO(2)Et)(2)](PPh(3))] is obtained. Halfsandwich-type ruthenium(II) complexes [(eta(5)-C(5)R(5))RuCl(=CHR')(PPh(3))] with secondary carbenes as ligands, as well as cationic species [(eta(5)-C(5)H(5))Ru(=CPh(2))(L)(PPh(3))]X with L=CO and CNtBu and X=AlCl(4) and PF(6), have also been prepared. The neutral compounds [(eta(5)-C(5)H(5))RuCl(=CRR')(PPh(3))] react with phenyllithium, methyllithium, and the vinyl Grignard reagent CH(2)=CHMgBr by displacement of the chloride and subsequent C-C coupling to generate halfsandwich-type ruthenium(II) complexes with eta(3)-benzyl, eta(3)-allyl, and substituted olefins as ligands. Protolytic cleavage of the metal-allylic bond in [(eta(5)-C(5)H(5))Ru(eta(3)-CH(2)CHCR(2))(PPh(3))] with acetic acid affords the corresponding olefins R(2)C=CHCH(3). The by-product of this process is the acetato derivative [(eta(5)-C(5)H(5))Ru(kappa(2)-O(2)CCH(3))(PPh(3))], which can be reconverted to the carbene complexes [(eta(5)-C(5)H(5))RuCl(=CR(2))(PPh(3))] in a one-pot reaction with R(2)CN(2) and Et(3)NHCl.     

Reaction of [M(eta3-allyl)(eta2-amidinato)(CO)2(pyridine)] complexes (M = Mo, W) with bidentate ligands: nitrogen donor vs. phosphorus donor

The reactivity of amidinato complexes of molybdenum and tungsten bearing pyridine as a labile ligand, [M(eta(3)-allyl)(eta(2)-amidinato)(CO)(2)(pyridine)](M = Mo; 1-Mo, M = W; 1-W), toward bidentate ligands such as 1,10-phenanthroline (phen) and 1,2-bis(diphenylphosphino)ethane (dppe) was investigated. The reaction of 1 with phen at ambient temperature resulted in the formation of monodentate amidinato complexes, [M(eta(3)-allyl)(eta(1)-amidinato)(CO)(2)(eta(2)-phen)](M = Mo; 2-Mo, M = W; 2-W), which has pseudo-octahedral geometry with the amidinato ligand coordinated to the metal in an eta(1)-fashion. The phen ligand was located coplanar with two CO ligands and the eta(1)-amidinato ligand was positioned trans to the eta(3)-allyl ligand. In solution, both complexes 2-Mo and 2-W showed fluxionality, and complex 2-Mo afforded allylamidine (3) on heating in solution. In the reaction of 1 with dppe at ambient temperature, the simple substitution reaction took place to give dppe-bridged binuclear complexes [{M(eta(3)-allyl)(eta(2)-amidinato)(CO)(2)}(2)(mu-dppe)](M = Mo; 5-Mo, M = W; 5-W), whereas mononuclear monocarbonyl complexes [M(eta(3)-allyl)(eta(2)-amidinato)(CO)(eta(2)-dppe)](M = Mo; 6-Mo, M = W; 6-W) were obtained under acetonitrile- or toluene-refluxing conditions. Mononuclear complex 6 was also obtained by the reaction of binuclear complex 5 with 0.5 equivalents of dppe under refluxing in acetonitrile or in toluene. The X-ray analyses and variable-temperature (31)P NMR spectroscopy of complex 6 indicated the existence of the rotational isomers of the eta(3)-allyl ligand, i.e., endo and exo forms, with respect to the carbonyl ligand. The different reactivity of complex 1 toward phen and dppe seems to have come from the difference in the pi-acceptability of each bidentate ligand.