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The coordinatively unsaturated tri-p-tolylgermyl complex RuCl(Ge[p-tolyl]3)(CO)(PPh3)2 (1) is obtained in good yield through the reaction between HGe(p-tolyl)3 and RuCl(Ph)(CO)(PPh3)2. On treatment of 1 with 1 equiv of NaS2CNR′2 (R′ = Et, Me), the chloride ligand is displaced and the corresponding coordinatively saturated complexes Ru(κ2-S2CNR′2)(Ge[p-tolyl]3)(CO)(PPh3)2 (2a, R′ = Et; 2b, R′ = Me) are formed. One of the PPh3 ligands in 2a is labile and undergoes substitution readily on addition of CO to give the cis-dicarbonyl complex Ru(κ2-S2CNEt2)(Ge[p-tolyl]3)(CO)2(PPh3) (3). On addition of NaS2CNMe2 to 2b, a PPh3 ligand is displaced by one sulfur atom while the other sulfur atom displaces one of the p-tolyl groups on germanium to give Ru(κ2(Ge,S)-Ge[p-tolyl]2S2CNMe2)(κ2-S2CNMe2)(CO)(PPh3) (4). Complex 4 is also formed on addition of excess NaS2CNMe2 to 1. Treatment of 1 with pyridine and ethanol under ambient conditions also results in cleavage of one of the germyl p-tolyl groups, and the product form...

Reaction between the cationic iridacyclopentadiene complex [Ir(C4H4)(NCMe)(CO)(PPh3)2][CF3SO3] (1) and methylpropiolate produces the cationic iridabenzofuran [Ir(C7H5O{OMe-7})(CO)(PPh3)2][CF3SO3] (2) in high yield. On treatment of 2 with chloride, the carbonyl ligand is displaced and the corresponding neutral iridabenzofuran Ir(C7H5O{OMe-7})Cl(PPh3)2 (3) is formed. The fused metallacyclic rings of the iridabenzofurans 2 and 3 bear only one substituent (OMe), and therefore these compounds are well suited for studies of electrophilic aromatic substitution reactions. Bromination of cationic 2 with pyridinium tribromide proceeds to give the monobrominated iridabenzofuran [Ir(C7H5O{OMe-7}{Br-6})(CO)(PPh3)2][CF3SO3] (4) exclusively. Bromination of neutral 3 with the same reagent gives the dibrominated iridabenzofuran Ir(C7H5O{OMe-7}{Br-6}{Br-2})Br(PPh3)2 (5) exclusively. Treatment of compound 3 with mercury(II) trifluoroacetate followed by excess bromide (to displace coordinated trifluoroacetate) produces the t...

The purple osmabenzene complex Os(C5H4{SMe-1})(CF3SO3)(CO)(PPh3)2 (1) is formed in high yield through reaction between Os(C5H4{S-1})(CO)(PPh3)2 and methyl triflate. The neutral blue osmabenzenes Os(C5H4{SMe-1})(cis-X)(CO)(PPh3)2 (X = I (2a), Cl (2b), SCN (2c), CF3CO2 (2d)) are readily obtained through treatment of 1 with the appropriate anion X−. In these complexes the geometry about osmium is approximately octahedral, with the two PPh3 ligands being mutually trans and X being cis to the SMe-substituted carbon of the metallabenzene ring. When solutions of 2a in benzene are heated under reflux, the I and CO ligands interchange positions and the brown isomeric osmabenzene Os(C5H4{SMe-1})(trans-I)(CO)(PPh3)2 (3a) is formed. However, if a solution of either 2a or 3a is heated under reflux in toluene, the metal-bound carbon atoms of the osmabenzene fragment couple and a mixture of the two cyclopentadienyl complexes [Os(η5-C5H4SMe)(CO)(PPh3)2]I (4a) and Os(η5-C5H4SMe)I(CO)(PPh3) (5a) is formed. Heating solution...

The cationic thiocarbonyl complex [Ir(CS)(MeCN)(PPh3)2][CF3SO3] (1) reacts sequentially with ethyne and LiCl to give the iridacyclopentadiene Ir[C4H4]Cl(CS)(PPh3)2 (2), which in turn when heated with methyl triflate followed by addition of LiCl produces the stable, purple, iridabenzene Ir[C5H4(SMe-1)]Cl2(PPh3)2 (3). This iridabenzene undergoes electrophilic aromatic bromination in the position para to the SMe substituent to form Ir[C5H3(SMe-1)(Br-4)]Br2(PPh3)2 (4).

Treatment of IrCl(CS)(PPh3)2 with an excess of KI gives orange IrI(CS)(PPh3)2 (1). IrI(CS)(PPh3)2 (1) reacts reversibly with dioxygen to form the brown dioxygen complex Ir(O2)I(CS)(PPh3)2 (2). Reaction between IrI(CS)(PPh3)2 (1) and 2 equiv of ethyne produces the green-brown tethered iridacyclobutadiene complex Ir[C3H2(CHCHS-1)]I(PPh3)2 (3), one ethyne combining in a cycloaddition reaction with the IrC multiple bond to the CS ligand to form the four-membered IrC3 ring and the second ethyne alkylating the sulfur atom to give the vinylthio substituent at the 1-position of the metallacyclic ring, which is tethered to the iridium through an Ir−C bond. In reactions related to those with ethyne, phenylacetylene reacts with IrCl(CS)(PPh3)2 to give as the major product the tethered iridacyclobutadiene Ir[C3H(CHC{Ph}S-1)(Ph-3)]Cl(PPh3)2 (4), with the phenyl substituent adjacent to the iridium, and as the minor product the isomeric tethered iridacyclobutadiene Ir[C3H(CHC{Ph}S-1)(Ph-2)]Cl(PPh3)2 (5). A thermal react...

Reaction between Os(SnI3)(κ2-S2CNMe2)(CO)(PPh3)2 and NaBH4 produces the unusual, air-stable, trihydridostannyl complex, Os(SnH3)(κ2-S2CNMe2)(CO)(PPh3)2 (1), which has been fully characterised including by X-ray crystal structure determination.Similarly, reaction between Os(SnI2Me)(κ2-S2CNMe2)(CO)(PPh3)2 or Os(SnClMe2)(κ2-S2CNMe2)(CO)(PPh3)2 and NaBH4 produces the dihydridostannyl complex, Os(SnH2Me)(κ2-S2CNMe2)(CO)(PPh3)2 (4) or the monohydridostannyl complex, Os(SnHMe2)(κ2-S2CNMe2)(CO)(PPh3)2 (6), respectively.The Sn H bonds in these complexes are reactive towards acids and in selected reactions complexes 1 and 4 with aqueous HF give Os(SnF3)(κ2-S2CNMe2)(CO)(PPh3)2 (3) and Os(SnF2Me)(κ2-S2CNMe2)(CO)(PPh3)2 (5), respectively, and complex 6 with aqueous HCl gives Os(SnClMe2)(κ2-S2CNMe2)(CO)(PPh3)2.The trihydridostannyl complex 1 reacts with chloroform to form the trichlorostannyl complex, Os(SnCl3)(κ2- S2CNMe2)(CO)(PPh3)2 (2). The crystal structures of 1–3, 5, and 6 have been determined.

Reaction between Os(SnClMe2)(κ2-S2CNMe2)(CO)(PPh3)2 and either LiSnMe3 or KSnPh3 produces the distannyl complexes, Os(SnMe2SnMe3)(κ2-S2CNMe2)(CO)(PPh3)2 (1) or Os(SnMe2SnPh3)(κ2-S2CNMe2)(CO)(PPh3)2 (3), respectively. Similarly, reaction between Os(SnClMe2)Cl(CO)2(PPh3)2 (6) and KSnPh3 produces the distannyl complex, Os(SnMe2SnPh3)Cl(CO)2(PPh3)2 (7). In the 119Sn NMR spectra of these stable osmium(II) distannyl complexes both the α-Sn and β-Sn atoms show well-resolved 119Sn–119Sn and 119Sn–117Sn coupling. Each of these three distannyl complexes can be selectively functionalised at the α-Sn atom by reaction with SnCl2Me2 giving Os(SnClMeSnMe3)(κ2-S2CNMe2)(CO)(PPh3)2 (2), Os(SnClMeSnPh3)(κ2-S2CNMe2)(CO)(PPh3)2 (4), and Os(SnClMeSnPh3)Cl(CO)2(PPh3)2 (8), respectively. Treatment of compounds 3 or 7 with iodine also cleaves one α-methyl group, selectively, to give Os(SnIMeSnPh3)(κ2-S2CNMe2)(CO)(PPh3)2 (5), or Os(SnIMeSnPh3)Cl(CO)2(PPh3)2 (9). Crystal structures for complexes 3 and 7 have been determined.

Silyl and stannyl complexes of ruthenium and osmium bearing halogen substituents on the silicon and tin atoms undergo many interesting reactions. While there are formal similarities, there are also...

The coordinatively unsaturated 1-iridaindene, Ir[C8H5(Ph-3)]Cl(PPh3)2 has a labile chloride ligand and is easily converted to the corresponding iodide, Ir[C8H5(Ph-3)]I(PPh3)2 (1) by reaction with NaI. When Ir[C8H5(Ph-3)]I(PPh3)2 (1) is treated with methyl propiolate a reactive five-coordinate complex with both a diphenylvinyl ligand from ring-opening of the 1-iridaindene, and a 3-methoxy-3-oxoprop-1-ynyl ligand from deprotonation of methyl propiolate, is first produced. Reaction of this complex with aqueous HCl generates the 2-iridafuran, Ir[OC3H(CH CPh2-3)(OMe-5)]ClI(PPh3)2 (2) probably from initial protonation at the β-carbon of the 3-methoxy-3-oxoprop-1-ynyl ligand to form a vinylidene ligand and subsequent migration of the diphenylvinyl ligand to the α-carbon of this ligand accompanied by oxygen coordination to iridium. Similar treatment of 1 with methyl propiolate followed by aqueous HI gives the corresponding complex, Ir[OC3H(CH CPh2-3)(OMe-5)]I2(PPh3)2 (3). The X-ray crystal structures of 2 and 3 together with NMR spectroscopic data confirm the 2-metallafuran structures of these complexes.

Reaction between the zerovalent nitrosyl complex, OsCl(NO)(PPh3)3 and 3,3-diphenylcyclopropene yields the robust π-adduct, Os(η2-3,3-diphenylcyclopropene)Cl(NO)(PPh3)2 (1), the crystal structure of which reveals the chloride and nitrosyl ligands located mutually trans and the Os, the two PPh3 ligands and the double bond of the cyclopropene, all lying in one plane. Treatment of 1 with the acids HX (X = Cl, O2CCF3) brings about a ring-opening of the cyclopropene ring (perhaps via an intermediate diphenylvinyl carbene complex) with the organic moiety remaining bound to osmium and with ultimate formation of the σ-diphenylallyl complexes, Os(CH2CH CPh2)Cl2(NO)(PPh3)2 (2) and Os(CH2CH CPh2)Cl(O2CCF3)(NO)(PPh3)2 (3), respectively. A crystal structure determination for 2 has been obtained.

Treatment of Os(κ 2 -S 2 CNMe 2 )H(CO)(PPh 3 ) 2 with HSiMeCl 2 or HSiCl 3 gives in high yield Os(κ 2 -S 2 CNMe 2 )(SiMeCl 2 )(CO)(PPh 3 ) 2 ( 1 ) or Os(κ 2 -S 2 CNMe 2 )(SiCl 3 )(CO)(PPh 3 ) 2 ( 2 ), respectively. The crystal structures of both compounds have been determined and the Os–Si distances are 2.3672(10) A for 1 and 2.3449(12) A for 2 . In solution, and under forcing conditions, both compounds are extraordinarily unreactive towards hydroxide ions.

Reaction between the diphenylacetylene complex Os(PhC⋮CPh)(CS)(PPh3)2 (1) and two molecules of HC⋮CCO2Me leads to a very stable, blue, osmabicylic complex with osmium at a bridgehead position. One way to consider this complex is as a metalla-aromatic molecule, viz., the osmabenzofuran Os[C7H2O(OMe-7)(CO2Me-4)(Ph-1)(Ph-2)](CS)(PPh3)2 (2). The bicyclic ring system is remarkably robust, and heating this compound in ethanol at reflux with aqueous HCl effects only a transesterification of the ester function in the six-membered ring (at the 4-position), forming Os[C7H2O(OMe-7)(CO2Et-4)(Ph-1)(Ph-2)](CS)(PPh3)2 (3). Reaction of Os[C7H2O(OMe-7)(CO2Me-4)(Ph-1)(Ph-2)](CS)(PPh3)2 (2) with pyridinium tribromide effects bromination in the five-membered ring of the osmabenzofuran at the 6-position to form Os[C7HO(OMe-7)(Br-6)(CO2Me-4)(Ph-1)(Ph-2)](CS)(PPh3)2 (4). Crystal structure determinations of 2, 3, and 4 confirm the osmabicyclic structure of each compound. Treatment of complex 2 with anhydrous trifluoroacetic acid...

Treatment of the six-coordinate trimethylstannyl complex, Os(SnMe3)(κ2-S2CNMe2)(CO)(PPh3)2 (1) with SnMe2Cl2 produces Os(SnMe2Cl)(κ2-S2CNMe2)(CO)(PPh3)2 (2), which in turn reacts readily with hydroxide ion to give, Os(SnMe2OH)(κ2-S2CNMe2)(CO)(PPh3)2 (3). The osmastannol complex 3 undergoes a reaction with 2 equivalents of tBuLi, in which one of the phenyl rings of a triphenylphosphine ligand is “ortho-stannylated”, without cleavage of the Os–Sn bond, to give the cyclic complex, Os(κ2(Sn,P)-SnMe2C6H4PPh2)(κ2-S2CNMe2)(CO)(PPh3) (4). This novel cyclic complex is selectively functionalised at the tin atom by reaction with SnMe2Cl2 which exchanges one methyl group for chloride giving the diastereomeric mixture, Os(κ2(Sn,P)-SnMeClC6H4PPh2)(κ2-S2CNMe2)(CO)(PPh3) (5a/5b). Crystal structure determination reveals that both diastereomers occur in the unit cell. The mixture, 5a/5b, undergoes reaction with hydroxide ion to give the diastereomeric osmastannol complexes, Os(κ2(Sn,P)-SnMeOHC6H4PPh2)(κ2-S2CNMe2)(CO)(PPh3) (6a/6b) and with sodium borohydride to give the corresponding tin-hydride mixture, Os(κ2(Sn,P)-SnMeHC6H4PPh2)(κ2-S2CNMe2)(CO)(PPh3) (7a/7b). Crystal structure determinations for 2, 4, and 5a/5b have been obtained.

Heating the five-coordinate trimethylstannyl complex, Os(SnMe3)Cl(CO)(PPh3)2, in solution with triphenylphosphine induces an ortho-stannylation of one phenyl group of a triphenylphosphine ligand and an ortho-metallation of another triphenylphosphine ligand, to produce the metallacyclic complexes, Os(κ2(Sn,P)-SnMeClC6H4PPh2)(κ2(C,P)-C6H4PPh2)(CO)(PPh3) (1) and Os(κ2(Sn,P)-SnMe2C6H4PPh2)(κ2(C,P)-C6H4PPh2)(CO)(PPh3) (2), suggesting the possible intermediacy of a complex with a coordinated stannylene ligand. Spectroscopic data indicate that only one diastereomer of 1 is formed and crystal structure determination of 1 reveals that this is the diastereomer with chloride directed towards the CO ligand. Complex 2 is converted to 1 through a redistribution reaction with SnMe2Cl2. Heating the six-coordinate trimethylstannyl complex, Os(SnMe3)Cl(CO)2(PPh3)2, in solution produces the osmium(II) methyl complex, Os(Me)(SnMe2Cl)(CO)2(PPh3)2 (3), through an exchange of methyl and chloride groups on the tin and osmium. In this rearrangement, the relative locations of the two CO ligands and the two PPh3 ligands remains unchanged. However, when the six-coordinate trimethylstannyl complex, Os(SnMe3)Cl(CO)2(PPh3)2 is heated under CO, the same exchange reaction is observed but the mono-triphenylphosphine, tricarbonyl complex, Os(Me)(SnMe2Cl)(CO)3(PPh3) (4), is produced and here the SnMe2Cl ligand is located trans to the PPh3 ligand. Crystal structure determinations for 1, 2, 3, and 4 have been obtained.

Reaction between Os(SiCl3)Cl(CO)(PPh3)2 and five equivalents of MeLi produces a colourless intermediate, tentatively formulated as the lithium salt of the six-coordinate, dimethyl, trimethylsilyl-containing complex anion, Li[Os(SiMe3)(Me)2(CO)(PPh3)2]. Reaction of this material with ethanol releases methane and gives the red, coordinatively unsaturated methyl, trimethylsilyl-containing complex, Os(SiMe3)(Me)(CO)(PPh3)2 (1). An alternative synthesis of 1 is to add one equivalent of MeLi to Os(SiMe3)Cl(CO)(PPh3)2, which in turn is obtained by adding three equivalents of MeLi to Os(SiCl3)Cl(CO)(PPh3)2. Treatment of 1 with p-tolyl lithium, again gives a colourless intermediate which may be Li[Os(SiMe3)(Me)(p-tolyl)(CO)(PPh3)2], and reaction with ethanol gives the red complex, Os(SiMe3)(p-tolyl)(CO)(PPh3)2 (3). Complexes 1 and 3 are readily carbonylated to Os(SiMe3)(Me)(CO)2(PPh3)2 (2) and Os(SiMe3)(p-tolyl)(CO)2(PPh3)2 (4), respectively. Heating Os(SiMe3)Cl(CO)(PPh3)2 in molten triphenylphosphine results only in loss of the trimethylsilyl ligand and formation of the previously known complex containing an ortho-metallated triphenylphosphine ligand, Os(κ2(C,P)-C6H4PPh2)Cl(CO)(PPh3)2. In contrast, heating the five-coordinate osmium-methyl complex, Os(SiMe3)(Me)(CO)(PPh3)2 (1), in the presence of triphenylphosphine results mainly, not in tetramethylsilane elimination, but in ortho-silylation as well as ortho-metallation of different triphenylphosphine ligands giving, Os(κ2(Si,P)-SiMe2C6H4PPh2)(κ2(C,P)-C6H4PPh2)(CO)(PPh3) (5). A byproduct of this reaction is the non-silicon containing di-ortho-metallated complex, Os(κ2(C,P)-C6H4PPh2)2(CO)(PPh3) (6). A similar reaction occurs when Os(SiMe3)(Me)(CO)(PPh3)2 (1) is heated in the presence of tri(N-pyrrolyl)phosphine producing Os(κ2(Si,P)-SiMe2C6H4PPh2)(κ2(C,P)-C6H4PPh2)(CO)[P(NC4H4)3] (7) but a better synthesis of 7 is to treat 5 directly with tri(N-pyrrolyl)phosphine. Heating the six-coordinate complex, Os(SiMe3)(Me)(CO)2(PPh3)2 (2), gives two complexes both containing ortho-metallated triphenylphosphine, one with loss of the trimethylsilyl ligand, giving the known complex, Os(κ2(C,P)-C6H4PPh2)H(CO)2(PPh3), and the other with retention of the trimethylsilyl ligand, giving Os(SiMe3)(κ2(C,P)-C6H4PPh2)(CO)2(PPh3) (8). Crystal structure determinations for 5, 6, 7 and 8 have been obtained.

Treatment of the five-coordinate chlorodimethylsilyl complex, Os(SiMe 2 Cl)Cl(CO)(PPh 3 ) 2 with hydroxide readily produces Os(SiMe 2 OH)Cl(CO)(PPh 3 ) 2 ( 1 ). Complex 1 is deprotonated by t BuLi giving the silanolate complex, Os(SiMe 2 OLi)Cl(CO)(PPh 3 ) 2 ( 2 ), which reacts further with Me 3 SiCl or Me 3 SnCl to give Os(SiMe 2 OSiMe 3 )Cl(CO)(PPh 3 ) 2 ( 3 ) or Os(SiMe 2 OSnMe 3 )Cl(CO)(PPh 3 ) 2 ( 4 ), respectively. The structures of 3 and 4 have been determined by X-ray crystallography. Reaction between OsH(κ 2 -S 2 CNMe 2 )(CO)(PPh 3 ) 2 and HSiMe 2 Cl gives Os(SiMe 2 Cl)(κ 2 -S 2 CNMe 2 )(CO)(PPh 3 ) 2 ( 5 ). This six-coordinate chlorodimethylsilyl complex, is unreactive towards hydroxide at room temperature and at 60 °C forms Os[Si(OH) 3 ](κ 2 -S 2 CNMe 2 )(CO)(PPh 3 ) 2 ( 7 ). Complex 5 is, however, smoothly converted to the hydroxy derivative, Os(SiMe 2 OH)(κ 2 -S 2 CNMe 2 )(CO)(PPh 3 ) 2 ( 6 ) upon chromatography on silica gel. Complex 6 is deprotonated by t BuLi giving the intermediate silanolate complex, Os(SiMe 2 OLi)(κ 2 -S 2 CNMe 2 )(CO)(PPh 3 ) 2 , which reacts further with Me 3 SiCl to give Os(SiMe 2 OSiMe 3 )(κ 2 -S 2 CNMe 2 ) (CO)(PPh 3 ) 2 ( 8 ). Crystal structure determinations for 5 , 6 , 7 , and 8 have been obtained and structural comparisons of these related compounds are made.

The thiocarbonyl analogue of Vaska’s compound is produced in high yield by first treating IrCl(CO)(PPh3)2 with CS2 and methyl triflate to give [Ir(κ2-C[S]SMe)Cl(CO)(PPh3)2]CF3SO3 (1), secondly, reacting 1 with NaBH4 to give IrHCl(C[S]SMe)(CO)(PPh3)2 (2), and finally heating 2 to induce elimination of both MeSH and CO to produce IrCl(CS)(PPh3)2 (3). When IrCl(CS)(PPh3)2 is treated with Hg(CH CHPh)2 the novel 2-iridathiophene, Ir[SC3H(Ph-3)(CH CHPh-5)]HCl(PPh3)2 (4) is produced. The X-ray crystal structure of the iodo-derivative of 4, Ir[SC3H(Ph-3)(CH CHPh-5)]HI(PPh3)2 (5) confirms the unusual 2-metallathiophene structure. Treatment of IrCl(CS)(PPh3)2 with Hg(CH CPh2)2 produces both a coordinatively unsaturated 1-iridaindene, Ir[C8H5(Ph-3)]Cl(PPh3)2 (6) and a chelated dithiocarboxylate complex, Ir(κ2-S2CCH CPh2)Cl(CH CPh2)(PPh3)2 (7). X-ray crystal structure determinations for 6 and 7 are reported.

Crystal structure determination of RuH(κ2-S2CNMe2)(CO)(PPh3)2 (1) confirms that the triphenylphosphine ligands are arranged mutually trans. 1 reacts readily with HSiClPh2 to eliminate H2 and produce the six-coordinate silyl complex, Ru(SiClPh2)(κ2-S2CNMe2)(CO)(PPh3)2 (2). Crystal structure determination of 2 reveals the same geometrical arrangement of ligands as in 1 with the silyl ligand replacing the hydride ligand. The chloride bound to silicon in 2 is replaced through reactions with 2-hydroxypyridine, 2-aminopyridine, and thallium acetate, producing, respectively, the mono-PPh3 complexes, Ru(κ2(Si,N)-SiPh2OC5H4N)(κ2-S2CNMe2)(CO)(PPh3) (3), Ru(κ2(Si,N)-SiPh2NHC5H4N)(κ2-S2CNMe2)(CO)(PPh3) (4), and Ru(κ2(Si,O)-SiPh2OCMeO)(κ2-S2CNMe2)(CO)(PPh3) (5). Crystal structure determinations of 3, 4, and 5 confirm that in each case there is formation of a five-membered chelate ring tethering the silyl ligand to ruthenium. In the formation of 3, 4, and 5 the Si-ligand and the two S atoms of the dimethyldithiocarbamate ligand remain meridional but the remaining triphenylphosphine ligand and the carbonyl ligand are interchanged in position leaving the donor atom of the tether trans to the CO ligand. An alternative way of considering the tethered silyl ligands in 3, 4, and 5 is as tethered, base-stabilised, silylene ligands and the structural data give some support for a contribution from this bonding model.

Treatment of either RuHCl(CO)(PPh3)3 or MPhCl(CO)(PPh3)2 with HSiMeCl2 produces the five-coordinate dichloro(methyl)silyl complexes, M(SiMeCl2)Cl(CO)(PPh3)2 (1a, M = Ru; 1b, M = Os). 1a and 1b react readily with hydroxide ions and with ethanol to give M(SiMe[OH]2)Cl(CO)(PPh3)2 (2a, M = Ru; 2b, M = Os) and M(SiMe[OEt]2)Cl(CO)(PPh3)2 (3a, M = Ru; 3b, M = Os), respectively. 3b adds CO to form the six-coordinate complex, Os(SiMe[OEt]2)Cl(CO)2(PPh3)2 (4b) and crystal structure determinations of 3b and 4b reveal very different Os–Si distances in the five-coordinate complex (2.3196(11) A) and in the six-coordinate complex (2.4901(8) A). Reaction between 1a and 1b and 8-aminoquinoline results in displacement of a triphenylphosphine ligand and formation of the six-coordinate chelate complexes M(SiMeCl2)Cl(CO)(PPh3)(κ2(N,N)-NC9H6NH2-8) (5a, M = Ru; 5b, M = Os), respectively. Crystal structure determination of 5a reveals that the amino function of the chelating 8-aminoquinoline ligand is located adjacent to the reactive Si–Cl bonds of the dichloro(methyl)silyl ligand but no reaction between these functions is observed. However, 5a and 5b react readily with ethanol to give ultimately M(SiMe[OEt]2)Cl(CO)(PPh3)(κ2(N,N-NC9H6NH2-8) (6a, M = Ru; 6b, M = Os). In the case of ruthenium only, the intermediate ethanolysis product Ru(SiMeCl[OEt])Cl(CO)(PPh3)(κ2(N,N-NC9H6NH2-8) (6c) was also isolated. The crystal structure of 6c was determined. Reaction between 1b and excess 2-aminopyridine results in condensation between the Si–Cl bonds and the N–H bonds with formation of a novel tridentate “NSiN” ligand in the complex Os(κ3(Si,N,N)-SiMe[NH(2-C5H4N)]2)Cl(CO)(PPh3) (7b). Crystal structure determination of 7b shows that the “NSiN” ligand coordinates to osmium with a “facial” arrangement and with chloride trans to the silyl ligand.

Reaction between Os[B(OEt)2]Cl(CO)(PPh3)2 and 1,2-ethanediol in the presence of Me3SiCl (1 equivalent) leads to the tethered boryl complex, Cl(CO)(PPh3)2 (1), in which one ethoxy substituent on the boryl ligand is exchanged with one hydroxy group of the 1,2-ethanediol leaving the other OH group available to coordinate to osmium, so giving a six coordinate complex. This formulation is confirmed by crystal structure determination. The same reactants, but with 2 equivalents of Me3SiCl, lead to the yellow, coordinatively unsaturated complex, Os Cl(CO)(PPh3)2 (2). Complex (2) adds CO to give Os Cl(CO)2 (PPh3)2 (3). Crystal structure determinations of 2 and 3 reveal a very marked difference in the Os–B distances found in the five coordinate complex 2 (2.043(4) A) and the six coordinate complex 3 (2.179(7) A). In a reaction similar to that used for forming 2 but with 1,3-propanediol replacing 1,2-ethanediol, the product is Os Cl(CO)(PPh3)2 (4). The crystal structure for 4 is also reported.

Reaction between the carbonyl, nitrosyl complex, OsCl(CO)(NO)(PPh3)2 (1) and dioxygen results in combination of CO and O2, forming a chelating peroxycarbonyl ligand in the yellow complex, Cl(NO)(PPh3)2 (2). Confirmation of the unique peroxycarbonyl ligand arrangement in 2 is provided by crystal structure determination. When 2 is heated, as a suspension in heptane under reflux, there is a rearrangement to the regular chelating carbonate ligand in the orange complex, Cl(NO)(PPh3)2 (3). The structure of 3 has also been determined by X-ray crystallography. Compound 2 also undergoes the following reactions: with water, releasing CO2 and forming Os(OH)2Cl(NO)(PPh3)2 (4); with HCl releasing CO2 and forming Os(OH)Cl2(NO)(PPh3)2 (5); and with excess triphenylphosphine releasing CO2 and triphenylphosphine oxide forming OsCl(NO)(PPh3)3 (6).

Reaction between Os(CO)2(PPh3)3 and Me3SnH produces Os(SnMe3)H(CO)2(PPh3)2 (1). Multinuclear NMR studies of solutions of 1 reveal the presence of four geometrical isomers, the major one being that with mutually cis triphenylphosphine ligands and mutually trans CO ligands. Os(SnMe3)H(CO)2(PPh3)2 undergoes a redistribution reaction, at the trimethylstannyl ligand, when treated with Me2SnCl2 giving Os(SnMe2Cl)H(CO)2(PPh3)2 (2). Solutions of 2 again show the presence of four isomers but now the major isomer is that with mutually trans triphenylphosphine ligands and mutually cis CO ligands. The redistribution reaction of 1 with SnI4 produces Os(SnMeI2)H(CO)2(PPh3)2 (3) which exists in solution as only one isomer, that with mutually trans triphenylphosphine ligands and mutually trans CO ligands. Treatment of 3 with I2 cleaves the Os–H bond with retention of geometry giving Os(SnMeI2)I(CO)2(PPh3)2 (4). The crystal structure of 4 has been determined. No isomerization of the trans dicarbonyl complex 4 occurs when 4 is heated, instead there is a formal loss of “MeSnI” and formation of OsI2(CO)2(PPh3)2 (5).

Reaction between the dichloroboryl complex, Os(BCl2)Cl(CO)(PPh3)2, and water replaces both chloride substituents on the boryl ligand, without cleavage of the OsB bond, giving yellow Os[B(OH)2]Cl(CO)(PPh3)2 (1). Compound 1 can be regarded as an example of a ‘metalla–boronic acid’ (LnMB(OH)2) and in the solid state, X-ray crystal structure determination reveals that molecules of 1 are tetragonal pyramidal in geometry (OsB, 2.056(3) A) and are arranged in pairs, as hydrogen-bonded dimers. This same arrangement is found in the crystalline state for simple boronic acids. Reaction between the dichloroboryl complex, Os(BCl2)Cl(CO)(PPh3)2, and methanol and ethanol produces yellow Os[B(OMe)2]Cl(CO)(PPh3)2 (2a) and yellow Os[B(OEt)2]Cl(CO)(PPh3)2 (2b), respectively. The crystal structure of 2b reveals a tetragonal pyramidal geometry with the diethoxyboryl ligand in the apical site and with an OsB bond distance of 2.081(5) A. Reaction between Os(BCl2)Cl(CO)(PPh3)2, and N,N′-dimethyl-o-phenylenediamine and N,N′-dimethyl-ethylenediamine produces yellow Os [ BN ( CH 3 ) C 6 H 4 N ( CH 3 )] Cl ( CO )( PPh 3 ) 2 (5) and yellow Os [ BN ( CH 3 ) C 2 H 4 N ( CH 3 )] Cl ( CO )( PPh 3 ) 2 (6), respectively. Compounds 1, 2a, 2b, 5, and 6 all react with carbon monoxide to give the colourless, six-coordinate complexes Os[B(OH)2]Cl(CO)2(PPh3)2 (3), Os[B(OMe)2]Cl(CO)2(PPh3)2 (4a), Os[B(OEt)2]Cl(CO)2(PPh3)2 (4b), Os [ BN ( CH 3 ) C 6 H 4 N ( CH 3 )] Cl ( CO ) 2 ( PPh 3 ) 2 (7), and Os [ BN ( CH 3 ) C 2 H 4 N ( CH 3 )] Cl ( CO ) 2 ( PPh 3 ) 2 (8), respectively, but in the case of 6 only, this CO uptake is easily reversible. The crystal structure of 5 is also reported.

Reaction between Os(BCl2)Cl(CO)(PPh3)2 and 2-aminopyridine in the presence of ethanol leads to a mixture of two products. In the first, replacement of one chloride on the dichloroboryl ligand through condensation with the amino function and coordination of the pyridine nitrogen atom to osmium leads to the tethered, six-coordinate boryl complex (1). In the second, the direction of addition of the aminopyridine is reversed, leading to the tethered, pyridine-stabilized borylene complex (2). The five-membered chelate ring formed in 1 is stable and persists through reactions involving replacement of chloride both at osmium and at boron. When 1 is treated with NaBr or with NaBH4, replacement of chloride at osmium occurs exclusively, leaving the B−Cl bond intact and giving (3) or (4), respectively. Replacement of chloride at boron requires the assistance of AgSbF6, and the following derivatives of 1 have been characterized: (5) (with 1 equiv of AgSbF6), (6) (with 2 equiv of AgSbF6 in MeCN), and (7) (with 2 equi...

Reaction between Os(BCl 2 )Cl(CO)(PPh 3 ) 2 and 2-hydroxypyridine leads to the replacement of one chloride on the dichloroboryl ligand and coordination of the pyridine nitrogen atom to osmium, leading to the six-coordinate complex Os[BCl(OC 5 H 4 N)]Cl(CO)(PPh 3 ) 2 (1). The five-membered chelate ring so formed is stable and persists through reactions involving replacement of chloride both at osmium and at boron. When 1 is treated with anhydrous HI, replacement of chloride at osmium occurs exclusively, leaving the B-Cl bond intact and giving Os[BCl(OC 5 H 4 N)]I(CO)(PPh3) 2 (2). However, the following nucleophilic substitution reactions at boron occur readily in 1: EtOH gives Os[B(OEt)(OC 5 H 4 N)]Cl(CO)(PPh3)2 (3), n-BuNH 2 gives Os[B(NHn-Bu)(OC 5 H 4 N)]Cl(CO)(PPh 3 ) 2 (4), and Et 3 N.3HF gives Os[BF-(OC 5 H 4 N)]Cl(CO)(PPh 3 ) 2 (5). Crystal structures of complexes 2 and 4 are reported.

Reaction between OsHCl(CO)(PPh3)3 and the powerful π-accepting ligand tris(N-pyrrolyl)phosphine, P(NC4H4)3, results in replacement of the PPh3 ligand trans to hydride giving OsHCl(CO)[P(NC4H4)3](PPh3)2 (1). The analogue of 1 with Cl replaced by p-tolyl, OsH(p-tolyl)(CO)[P(NC4H4)3](PPh3)2 (3), is accessible by thermal decarboxylation of Os(p-tolyl)(η2-O2CH)(CO)(PPh3)2 (2) in the presence of P(NC4H4)3. Complex 3, despite having cis-hydride and p-tolyl ligands, is resistant to reductive elimination of toluene. Osmium(0) complexes containing P(NC4H4)3 are conveniently prepared by replacement of one PPh3 ligand from Os(CO)(CE)(PPh3)3 (E=O, S) to give Os(CO)(CE)[P(NC4H4)3](PPh3)2 (4, E=O; 5, E=S). Structure determination of 4 confirms a trigonal bipyramidal geometry with the PPh3 ligands in the axial positions and the π-accepting P(NC4H4)3 ligand in the expected equatorial site.

Treatment of Os(SiMe 2 Cl)Cl(CO)(PPh 3 ) 2 with an excess of the amino-substituted silane, HSiMe 2 NMe 2 , produces a mixture of two products, the relative proportions of which depend upon the reaction conditions. These are, Os(SiMe 2 NMe 2 S iMe 2 )Cl(CO)(PPh 3 ) 2 ( 1 ) and Os(SiMe 2 NMe 2 S iMe 2 )H(CO)(PPh 3 ) 2 ( 2 ). Similar treatment of Ru(SiMe 2 Cl)Cl(CO)(PPh 3 ) 2 with HSiMe 2 NMe 2 produces the ruthenium analogues of 1 and 2 , Ru(SiMe 2 NMe 2 S iMe 2 )Cl(CO)(PPh 3 ) 2 ( 3 ), and Ru(SiMe 2 NMe 2 S iMe 2 )H(CO)(PPh 3 ) 2 ( 4 ), together with a third compound, the novel dimethylsilylene-bridged diruthenium complex, [ Ru(SiMe 2 NMe 2 S iMe 2 )(CO)(μ-{SiMe 2 }) 2 (μ-Cl)RuH 2 (CO)(PPh 3 )] ( 5 ). A ligand exchange reaction occurs when 3 is treated with 1,2-bis(diphenylphosphino)ethane (dppe) yielding Ru(SiMe 2 NMe 2 S iMe 2 )Cl(CO)(dppe) ( 6 ), in which the bis(silylene) ligand is retained. Crystal structures of 1 , 2 , 4 , and 6 reveal that the RuSiNS i and OsSiNS i rings of the bis(silylene) ligand system are folded at the Si atoms and the RuSi and OsSi distances are short, while SiN distances are long. These structural data suggest some multiple bond character in the metal–silicon bonds and this is further supported by the down-field chemical shifts observed in the 29 Si-NMR spectra of these compounds. A crystal structure has also been determined for the diruthenium complex 5 and this reveals a RuRu distance of 2.7557(2) A, and two unsymmetrically bridging dimethylsilylene ligands each with a close approach to one of the ruthenium hydride ligands (SiH, 1.56(2) and 1.67(2) A).

Reaction between OsPhCl(CO)(PPh 3 ) 2 and HSi(OEt) 3 gives the five-coordinate complex, Os[Si(OEt) 3 ]Cl(CO)(PPh 3 ) 2 ( 1 ), the crystal structure of which reveals a square pyramidal geometry with the triethoxysilyl ligand at the apical site and the two triphenylphosphine ligands arranged mutually trans . Addition of CO gives the six-coordinate complex, Os[Si(OEt) 3 ]Cl(CO) 2 (PPh 3 ) 2 ( 2 ), but this addition is thermally reversible. The chloride ligand in 1 is replaced easily and reaction with LiR gives the stable, five-coordinate complexes, Os[Si(OEt) 3 ]R(CO)(PPh 3 ) 2 ( 3a , R=phenyl; 3b , R= o -tolyl). Crystal structure determinations for 3a and 3b reveal a coordination geometry almost unchanged from that of 1 with Cl replaced by phenyl and o -tolyl, respectively. Addition of CO to 3a and 3b gives the six-coordinate complexes, Os[Si(OEt) 3 ]R(CO) 2 (PPh 3 ) 2 ( 4a , R=phenyl) ( 4b , R= o -tolyl). Crystal structure determinations for 4a and 4b confirm octahedral geometry for each compound. Despite having adjacent aryl and silyl ligands neither 3a , 3b nor 4a , 4b show any tendency to undergo reductive elimination of RSi(OEt) 3 . IR, 1 H-, 13 C- and 29 Si-NMR data for all new complexes are presented.

Reaction between Os(CS)(CO)(PPh 3 ) 3 and propyne gives a complex mixture of products from which can be isolated the simple oxidative addition product Os(CCMe)H(CS)(CO)(PPh 3 ) 2 ( 1 ) and the osmabenzene Os(η 2 -C[S]CMeCHCHC Me)(CO)(PPh 3 ) 2 ( 2 ), where the two propyne molecules in the osmabenzene ring have linked tail-to-tail. Treatment of 1 with HCl gives, as the ultimate product, the propenylthioacyl complex, Os(η 2 -C[S]CHCHMe)Cl(CO)(PPh 3 ) 2 ( 3 ). The crystal structures of compounds 1 – 3 have been determined.

A convenient preparation of Hg[C6H4(CH2OH)-2]Cl (1) involves treatment of dilithiated benzyl alcohol with HgCl2. 1 is smoothly oxidised to Hg[C6H4(CHO)-2]Cl (2) by reaction with pyridinium chlorochromate (PCC). The crystal structure of 2 reveals a two coordinate linear arrangement at mercury supplemented by weaker interactions with the aldehyde oxygen atoms both intramolecularly and intermolecularly. Treatment of 2 with NaI effects symmetrisation with the formation of Hg[C6H4(CHO)-2]2 (3). Reaction between 3 and the Wittig reagent Ph3PCH2 results in the formation of Hg[C6H4(CHCH2)-2]2 (4). The crystal structure of 4 has been determined.

Reaction of Os(Bcat)Cl(CO)(PPh3)2 (1) (HBcat = catecholborane or 1,3,2-benzodioxaborole) with o-tolyllithium gives the yellow, five-coordinate Bcat, aryl complex Os(Bcat)(o-tolyl)(CO)(PPh3)2 (2). Treatment of 2 with carbon monoxide or p-tolylisocyanide gives the corresponding saturated Bcat, aryl complexes cis-Os(Bcat)(o-tolyl)(CO)2(PPh3)2 (3) and cis-Os(Bcat)(o-tolyl)(CO)(CN-p-tolyl)(PPh3)2 (4). Complexes 3 and 4 decompose in benzene solution at room temperature to give o-tolylBcat and the orthometalated triphenylphosphine complexes (5) and (as a mixture of two isomers, 6a and 6b), respectively. In the presence of B2cat2, 3 and 4 react to give the bis(Bcat) complexes Os(Bcat)2(CO)2(PPh3)2 (7) and Os(Bcat)2(CO)(CN-p-tolyl)(PPh3)2 (8). Complex 3 also reacts with HBcat to produce Os(Bcat)H(CO)2(PPh3)2 (9). The bis(Bcat) ruthenium complexes Ru(Bcat)2(CO)2(PPh3)2 (10) and Ru(Bcat)2(CO)(CN-p-tolyl)(PPh3)2 (11) can be prepared by treatment of Ru(CO)2(PPh3)3 or Ru(CO)(CN-p-tolyl)(PPh3)3 with B2cat2. Complex 3 re...

Reaction between Os(CO) 2 (PPh 3 ) 3 and the silatrane, HSi{OCH 2 CH 2 } 3 N, gives the osmium(II) silatranyl, hydride complex Os(Si{OCH 2 CH 2 } 3 N)H(CO) 2 (PPh 3 ) 2 ( 1 ), as a mixture of three isomers, the structures of which were determined by NMR spectroscopy. Reaction between OsH 4 (PPh 3 ) 3 and the silatrane, HSi{OCH 2 CH 2 } 3 N, gives the osmium(IV) silatranyl, trihydride complex Os(Si{OCH 2 CH 2 } 3 N)H 3 (PPh 3 ) 3 ( 2 ). The crystal structure of 2 has been determined and all three hydride ligands located. The three hydrides all make close approaches to the silicon atom but the distances between silicon and each of the hydrides suggests that any Si⋯H interactions must be weak. The interatomic distance between Si and N in the silatranyl ligand is large and the nitrogen atom has near planar geometry. Compound 2 can be methylated or protonated at nitrogen giving the complexes [Os(Si{OCH 2 CH 2 } 3 NMe)H 3 (PPh 3 ) 3 ]I ( 3 ), and [Os(Si{OCH 2 CH 2 } 3 NH)H 3 (PPh 3 ) 3 ]CF 3 SO 3 ( 4 ), respectively.

Reaction between MHCl(CO)(PPh3)3 (M=Ru, Os) and the o-halophenyl mercury compounds, Hg(C6H4X-2)2 (X=Cl, Br, I) gives the five co-ordinate complexes, M(C6H4X-2)Cl(CO)(PPh3)2 (1a M=Ru, X=Cl; 1b M=Ru, X=Br; 2a M=Os, X=Cl; 2b M=Os, X=Br; 2c M=Os, X=I). In these complexes there is a significant bonding interaction between the coordinatively unsaturated metal centre and the o-halo-substituent on the σ-bound phenyl group as revealed by crystal structure determinations of 2a, 2b, and 2c. Each of the five-coordinate complexes readily adds CO forming the corresponding six-coordinate dicarbonyl complexes, M(C6H4X-2)Cl(CO)2(PPh3)2 (5a M=Ru, X=Cl; 5b M=Ru, X=Br; 6a M=Os, X=Cl; 6b M=Os, X=Br; 6c M=Os, X=I). Crystal structure determination of 6a confirms regular octahedral geometry for these six-coordinate complexes with no interaction between the metal centre and the o-halo-substituent on the σ-bound phenyl group. The complexes 1a, b, 2a–c, 5a, b, 6a–c, are potentially precursors of benzyne complexes through reduction (removal of ClX) but all attempts at reduction were unsuccessful. The related thiocarbonyl complexes, Os(C6H4X-2)Cl(CS)(PPh3)2 (7a X=Cl; 7b X=Br) and Os(C6H4X-2)Cl(CO)(CS)(PPh3)2 (8a X=Cl; 8b X=Br), have been prepared similarly beginning with OsHCl(CS)(PPh3)3. The crystal structure of 8a has been determined. Both 8a and 8b undergo a slow migratory-insertion reaction upon heating to yield the corresponding η2-thioacyl complexes, Os(η2-C[S]C6H4X-2)Cl(CO)(PPh3)2 (9a X=Cl; 9b X=Br), the crystal structures of both of which have been determined. Once the o-halophenyl group is no longer directly bonded to the metal, as in 9a and 9b, normal reactivity returns to the o-halo substituent and 9b undergoes lithium–bromine exchange when treated with n-butyllithium and the resulting lithiated material, when treated with SnnBu3Cl, gives Os(η2-C[S]C6H4SnnBu3-2)Cl(CO)(PPh3)2 (10).

Treatment of the coordinatively unsaturated osmium complex Os(SnMe3)Cl(CO)(PPh3)2 with sodium dimethyldithiocarbamate gives the coordinatively saturated complex Os(SnMe3)(η2-S2CNMe2)(CO)(PPh3)2 (1). Complex 1 reacts with excess SnI4 to give Os(SnMeI2)(η2-S2CNMe2)(CO)(PPh3)2 (3) in high yield. A redistribution reaction of 3 with an equimolar amount of 1 provides Os(SnMe2I)(η2-S2CNMe2)(CO)(PPh3)2 (2). The last remaining methyl group bonded to tin in 3 is removed by treatment with a slight excess of I2, giving the triiodostannyl complex Os(SnI3)(η2-S2CNMe2)(CO)(PPh3)2 (4). Both 3 and 4 have been further derivatized by replacement of the halide groups on tin. Treatment of 3 with pyridinium tribromide gives Os(SnMeBr2)(η2-S2CNMe2)(CO)(PPh3)2 (5). Treatment of 3 with catechol provides Os(SnMe[1,2-O2C6H4])(η2-S2CNMe2)(CO)(PPh3)2 (6), while the similar reaction with 1,2-ethanedithiol gives Os(SnMe[1,2-S2C2H4])(η2-S2CNMe2)(CO)(PPh3)2 (7). Complex 4 undergoes reaction with an excess of KOH to give the trihydroxysta...

The reaction between [Hg(o-C6H4PPh2)2] and [MHCl(CO)(PPh3)3] gives the complexes [ MCl(o-C 6 H 4 P Ph2)(CO)(PPh3)2] [M=Ru (1), Os (2)], which contain a four-membered cyclometallated ring. A single-crystal X-ray diffraction study of 2 shows the geometry about osmium to be distorted octahedral with the phosphorus atoms in a meridional arrangement. Both complexes react with CO, which displaces one of the triphenylphosphine ligands, the product from 2 being [ OsCl(o-C 6 H 4 P Ph2)(CO)2(PPh3)]. In the case of 1, there is an accompanying migratory insertion of coordinated CO into the RuC bond to give the five-membered cyclic acyl complex [ RuCl(o-C(O)C 6 H 4 P Ph2)(CO)2(PPh3)]. Complex 2 reacts with AgSbF6 in the presence of CO to give [ Os(o-C 6 H 4 P Ph2)(CO)2(PPh3)2]SbF6.

Three nitrogen-containing aromatic heterocycles, 2-(1′-naphthyl)pyridine, 2-phenylquinoline, and 2,3-diphenylquinoxaline, have been mercurated in the naphthyl or phenyl ring 2-position and then symmetrised to form the mercury compounds Ar2Hg (Ar=Nppy (3), Phqn (1) or Dpqx (5), respectively). These reagents are suitable for trans-metallation and reaction with MHCl(CO)(PPh3)3 affords the complexes M(η2-C,NAr)Cl(CO)(PPh3)2, (6, M=Ru, Ar=Nppy; 7, M=Os, Ar=Nppy; 8, M=Ru, Ar=Phqn; 9, M=Os, Ar=Phqn; 10, M=Ru, Ar=Dpqx; 11, M=Os, Ar=Dpqx) in which each product features an aryl ligand that forms a strongly chelated five-membered ring through coordination of the heterocyclic N atom. The chloride ligand in each of the complexes 6–11 can be replaced by dimethyl dithiocarbamate to give ultimately the mono-triphenylphosphine complexes, M(η2-Ar)(η2-S2CNMe2)(CO)(PPh3) (12, M=Ru, Ar=Nppy; 13, M=Os, Ar=Nppy; 14, M=Ru, Ar=Phqn; 15, M=Os, Ar=Phqn; 16, M=Ru, Ar=Dpqx; 17, M=Os, Ar=Dpqx). Similarly, compound 10 when treated with Na(acac) gives Ru(η2-Dpqx)(η2-acac)(CO)(PPh3) (18), while treatment with trifluoroacetic acid gives Ru(η2-Dpqx)(O2CCF3)(CO)(PPh3)2 (19). Many of these complexes were found to be very robust, making them suitable for electrophilic aromatic substitution reactions under harsh conditions. In each case, the presence of the metal had both an activating and a directing effect on the aryl ring to which it was bonded. Bromination or nitration reactions, both of which are not normally possible with organometallic substrates, were carried out successfully, giving rise to monobrominated or dinitrated products, respectively. The following compounds were characterised, M(η2-Ar-4-Br)Cl(CO)(PPh3)2 (20, M=Ru, Ar=Phqn; 21, M=Os, Ar=Phqn; 22, M=Ru, Ar=Dpqx; 24, M=Os, Ar=Dpqx), M(η2-Dpqx-4-Br)(η2-S2CNMe2)(CO)(PPh3) (23, M=Ru; 25, M=Os), Os(η2-Ar)Cl(CO)(PPh3)2 (26, Ar=Nppy-6,8-(NO2)2; 27, Ar=Phqn-4,6-(NO2)2). Crystal structures of compounds 7, 12, 15, 18, 19, 21, 23 and 25 have been determined.

Reaction between (PyPh)2Hg (PyPh = 2-(2‘-pyridyl)phenyl) and MHCl(CO)(PPh3)3 proceeds smoothly to form M(η2-PyPh)Cl(CO)(PPh3)2 (M = Ru (1a); M = Os (1b)). In both complexes the PyPh ligand is bound as a stable five-membered chelate ring. The chloride ligand in these complexes can be removed through reaction with a silver salt and other ligands then introduced. In this way the compounds M(η2-PyPh)I(CO)(PPh3)2 (M = Ru (2a); M = Os (2b)), [M(η2-PyPh)(CO)2(PPh3)2]SbF6 (M = Ru (3a); M = Os (3b)), and M(η2-PyPh)(η2-S2CNMe2)(CO)(PPh3) (M = Ru (4a); M = Os (4b)) have been prepared. The coordinated PyPh ligand in 1a and 1b is activated by the metal toward electrophilic substitution at the phenyl ring. Nitration occurs in both the phenyl 4- and 6-positions of 1a or 1b, i.e., ortho and para to the metal, to give M(η2-PyPh-4,6-(NO2)2)Cl(CO)(PPh3)2 (M = Ru (5a); M = Os (5b)). Under appropriate conditions the mono-nitrated derivative, Os(η2-PyPh-4-NO2)Cl(CO)(PPh3)2 (5c), can also be isolated. Bromination of 1a or 1b oc...

Support for key steps of the mechanism for the transition metal catalyzed hydroboration reaction is provided by the characterization and reactions of 1, a cis-(boryl)(aryl) complex of osmium(II). This compound readily eliminates o-tolylBcat to give the osmium(0) intermediate 2, which in the presence of HBcat reestablishes the osmium-boron bond by forming 3. R=o-tolyl, H2 cat=catechol=1,2-(HO)2 C6 H4 .

Treatment of Os(Bcat)Cl(CO)(PPh3)2 (1; Bcat = B-1,2-O2C6H4) with AgSbF6 in THF removes chloride and gives a cationic boryl complex formulated as [Os(Bcat)(CO)(THF)2(PPh3)2]SbF6. This in turn when t...

When treated with lithium triethylborohydride, the cationic carbyne complexes [Os(–CR)(CO)2(PPh3)2]+(R=1-naphthyl, 1; R=2-naphthyl, 2) form 3 and 4, respectively, which both have the formula Os(C11H8)(CO)2(PPh3)2. NMR studies of these two isomeric vinylidene complexes show that the product derived from the 1-naphthyl carbyne cation involves attack at the naphthyl ring in the position para to the carbyne carbon to give 3, while that derived from the 2-naphthyl carbyne cation involves attack at the naphthyl ring in the position ortho to the carbyne carbon to give 4. The structure of 4 has been confirmed by an X-ray crystal structure determination. Addition of HCl to the vinylidene complexes 3 or 4 results in the formation of the corresponding naphthylmethyl complexes, Os(CH2R)Cl(CO)2(PPh3)2 (R=1-naphthyl, 5; R=2-naphthyl, 6).

Treatment of the dichlorocarbene-containing complex, Os(CCl2)Cl2(CO)(PPh3)2 with two equivalents of 1-naphthyllithium or two equivalents of 2-naphthyllithium in the presence of N,N,N′,N′-tetramethylethylenediamine (tmeda) gives the corresponding carbyne-containing complexes Os(CR)Cl(CO)(PPh3)2 (R=1-naphthyl (1); R=2-naphthyl (2)). Similar treatment of Ru(CCl2)Cl2(CO)(PPh3)2 with two equivalents of phenyllithium or 1-naphthyllithium yields Ru(CR)Cl(CO)(PPh3)2 (R=Ph (3); R=1-naphthyl (4)). When 1, 2, 3 and 4 are carbonylated in the presence of AgClO4 the corresponding carbyne-containing cations [M(CR)(CO)2(PPh3)2]ClO4 are formed (M=Os, R=1-naphthyl (5); M=Os, R=2-naphthyl (6); M=Ru, R=Ph (7); M=Ru, R=1-naphthyl (8)). When Ru(CPh)Cl(CO)(PPh3)2 is added to an acetonitrile solution containing two equivalents of AgClO4 in the absence of CO the complex [Ru(CPh{AgOClO3})(NCMe)(CO)(PPh3)2]ClO4 (9) can be isolated. Addition of LiCl to 9 yields the complex Ru(CPh{AgCl})Cl(CO)(PPh3)2 (10). The acids HX react with the neutral carbyne complexes 1, 2, 3 or 4 to form the corresponding carbene complexes M(CHR)ClX(CO)(PPh3)2 (M=Os, R=1-naphthyl, X=Cl (11); M=Os, R=2-naphthyl, X=Cl (12); M=Ru, R=Ph, X=Cl (13); M=Ru, R=1-naphthyl, X=Cl (14); M=Os, R=1-naphthyl, X=ClO4 (15); M=Os, R=1-naphthyl, X=F (16)). Treatment of complexes 1 or 2 with PhICl2 leads to corresponding monochlorocarbene-containing complexes Os(CClR)Cl2(CO)(PPh3)2 (R=1-naphthyl (17); R=2-naphthyl (18)) which subsequently rearrange on addition of aqueous base to give the σ-naphthyl, dicarbonyl complexes OsRCl(CO)2(PPh3)2 (R=1-naphthyl (19); R=2-naphthyl (20)). The single crystal X-ray structures of [Os(C-1-naphthyl)(CO)2(PPh3)2]ClO4, Os(CH-2-naphthyl)Cl2(CO)(PPh3)2, and Os(2-naphthyl)Cl(CO)2(PPh3)2 have been determined.

Ethyne inserts readily into the Ru−B bond of the five-coordinate boryl complex Ru(BO2C6H4)Cl(CO)(PPh3)2 (1) to form the borylalkenyl (2). Complex 2 has been characterized by IR and multinuclear NMR spectroscopy and by an X-ray crystal structure determination. In the solid state, the Ru atom in 2 is six coordinate through weak attachment of a catechol oxygen to ruthenium. Two further (4), which result from transesterification of 2 with HOCH2CH2OH and 3 with CH3CH2OH, respectively, are also described. The relevance of the observed ethyne insertion for metal-catalyzed hydroboration is discussed.

Os(SiCl3)Cl(CO)(PPh3)2 is prepared by treatment of OsPhCl(CO)(PPh3)2 with excess HSiCl3 and serves in turn as the starting material for the syntheses of three more five-coordinate silyl complexes Os(SiR3)Cl(CO)(PPh3)2 (R = F, OH, Me) via substitution of the chloride groups on silicon. All four compounds were fully characterized, including a single-crystal solid-state structure of each derivative. Carbonyl stretching frequencies decrease and Os−Si bond lengths increase as R changes in the order from F to Cl to OH to Me. Ab initio calculations were performed on the model complexes Os(SiR3)Cl(CO)(PH3)2 (R = F, Cl, OH, Me) to explain the trends observed in the IR and X-ray studies, and the importance of the π-acceptor capacities of the silyl groups are discussed.

The compounds [M(SiR3)H3(PPh3)3] (1: M = Ru, R = 1 - NC4H4 = pyr; 2a-c: M = Os, R = pyr, Et, Ph) are prepared through reaction of either [RuH2(PPh3)4] or [OsH4(PPh3)3] with the appropriate silane HSiR3 (3a-c: R = pyr, Et, Ph). The X-ray structure analysis of compound 2 a and ab initio calculations on the model compounds [Os(SiR3)H3(PH3)3] (4a-c: R = H, NH2, pyr) reveal a trigonal distortion along the Os-Si axis from an idealised tetrahedral geometry for the central OsSiP3 heavy-atom skeleton. The structure can be described as two face-shared octahedra, one based on osmium (OsH3P3) and the other based on silicon (SiH3N3). Studies of the bonding situation in 2 a reveal that the N-pyrrolyl substituents have a marked shortening effect on the osmium-silicon distance (229.3(3) pm) and that each of the three hydride ligands participates in partial three-centre bonding involving osmium, silicon and hydrogen. 1H, 13C, 29Si and 31P NMR spectra were used to determine the solution structures of complexes 1 and 2 a.

Oxidative addition of the tin-hydride bond of (p-tolyl)3SnH to the formal osmium(0) nitrosyl complexes, OsCl(NO)(PPh3)3 and “OsH(NO)(PPh3)2”, affords the osmium(II) stannyl complexes, Os[Sn(p-tolyl)3]HCl(NO)(PPh3)2 (1), and Os[Sn(p-tolyl)3]H2(NO)PPh3)2 (2) respectively. “OsH(NO)(PPh3)2” was generated in situ by thermal elimination of H2 from OsH3(NO)(PPh3)2 (5). It was established from 1H and 31P NMR evidence that 1 has two cis phosphine ligands, one of which is trans to the hydride ligand and the other trans to the stannyl ligand. The high trans influence of the hydride ligands confers lability on one phosphine ligand, which can be readily replaced by reaction with sodium dimethyldithiocarbamate forming OsH[Sn(p-tolyl)3](S2CNMe2)(NO)(PPh3) (3), and reaction with carbon monoxide gives eventually, after displacement of one triphenylphosphine and loss of HCl, Os[Sn(p-tolyl)3](NO)(CO)2(PPh3) (4), a formal osmium(O) stannyl complex. The crystal structure of this five-coordinate osmium-tin complex, 4, has been determined.

The development of a new, simple synthesis of tri-N-pyrrolylsilane (1) from trichlorosilane and pyrrole provides a convenient starting point for a series of interesting transition-metal complexes w...