Dafydd ap Kendrick

The synthesis and reactions with neutral monodentate ligands of the seven-coordinate complex [MoCl(GeCl3)(CO)3(NCMe)2]

Abstract The reaction of fac -[Mo(CO) 3 (NCMe) 3 ] (prepared in situ ) with an equimolar quantity of GeCl 4 rapidly affords the molybdenum(II) seven-coordinate complex [MoCl(GeCl 3 )(CO) 3 (NCMe) 2 ] ( 1 ) in quantitative yield. Equimolar quantities of 1 and L (L = PPh 3 , AsPh 3 or SbPh 3 ) react in CH 2 Cl 2 or NCME to give [MoCl(GeCl 3 )(CO) 3 (NCMe)L] or [MoCl(GeCl 3 )(CO) 2 (NCMe) 2 L], respectively. The reactions of [MoCl(GeCl 3 )(CO) 3 (NCMe)(PPh 3 )] and [MoCl(GeCl 3 (CO) 2 (NCMe) 2 (PPh3)] with a series of neutral and anionic donor ligands are described. Complex 1 reacts with two equivalents of L (L = PPh 3 , AsPh 3 , SbPh 3 or PPh 2 Cy) in CH 2 Cl 2 to afford [MoCl(GeCl 3 )(CO) 2 (NCMe)(PPh 3 ) 2 ] and [MoCl(GeCl 3 )(CO) 3 L 2 ]. Reactions of [MoCl](GeCl 3 )(CO) 2 (NCMe)(PPh 3 ) 2 ] are also discussed.

Preparation and spectroscopic properties of a series of new bimetallic phosphine-bridged seven-coordinate complexes of the type [M4I4(CO)6L2(μ-L L] {M = Mo or W; L = PPh3, AsPh3 or SbPh3; L L = Ph2P(CH2)nPPh2 (n = 1, 2 or 4); L L = [Fe(η5-C5H4PPh2)2]}

Reaction of the complexes [MI2(CO)3(NCME)2](M = Mo or W) with one equivalent of L(L = PPh3, AsPh3 or SbPh3) in CH2Cl2 at room temperature gives [MI2(CO)3(NCMe)L], which when treated in situ with half an equivalent of L L {L L = Ph2P(CH2nPPh2, n = 1, 2 or 4; L L = [Fel(η5-C5H4PPh2)2]} affords the new bimetallic seven-coordinate complexes [M2I4(CO)6L2(μ-L L)] in high yield. 31P NMR studies suggest that reaction of [WI2(CO)3(NCMe)(AsPh3)] with an equimolar amount of Ph2P(CH2)4PPh2 gives a mixture of [W2I4(CO)6(AsPh3)2{μ-Ph2P(CH2)4PPh2}], [WI2(CO)3(AsPh3)-{η1-Ph2P(CH2)4PPh2}] and unchanged Ph2P(CH2)4PPh2.

Triphenylphosphineoxide and triphenylphosphinesulfide seven-coordinate complexes of molybdenum(II) and tungsten(II)

Abstract The complexes [MI 2 (CO) 3 (NCMe) 2 ] (MMo or W) react with one equivalent of OPPh 3 in CH 2 Cl 2 at room temperature to rapidly afford the iodo-bridged dimers [M(μ-I)I(CO) 3 (OPPh 3 )] 2 in good yield. By contrast reaction of equimolar quantities of SPPh 3 and [MI 2 (CO) 3 (NCMe) 2 ] react in CH 2 Cl 2 at room temperature to give the monoacetonitrile monomers [MI 2 (CO) 3 (NCMe)(SPPh 3 )]. The monomers [MI 2 (CO) 3 (NCMe)(SPPh 3 )] dimerise very slowly on stirring at room temperature in CH 2 Cl 2 for 24 h to eventually give the iodo-bridged dimers [M(μ-I)I(CO) 3 (SPPh 3 )] 2 . The molybdenum iodo-bridged compound [Mo(μ-I)I(CO) 3 (OPPh 3 )] 2 reacts with two equivalents of L (LPPh 3 , AsPh 3 or P(OPh) 3 ) to rapidly give the bridged cleaved products [MoI 2 (CO) 3 L(OPPh 3 )]. The monoacetonitrile complexes [MI 2 (CO) 3 (NCMe)(SPPh 3 )] react in situ with an equimolar quantity of [NBu n 4 ]I in CH 2 Cl 2 at room temperature to give the expected anionic compounds [NBu n 4 ][MI 3 (CO) 3 (SPPh 3 )] in good yield. The bis- acetonitrile compounds [MI 2 (CO) 3 (NCMe) 2 ] react with two equivalents of L (LOPPh 3 or SPPh 3 ) in CH 2 Cl 2 to afford the bis-ligand compounds [MI 2 - (CO) 3 L 2 ] in high yield. However, one equivalent of L (LOPPh 3 or SPPh 3 ) reacts with [MI 2 (CO) 3 L 2 ] to give the monocationic complexes [MI(CO) 3 L 3 ]I. The ionic nature of these complexes was confirmed by the formulation of the complex [MoI(CO) 3 - (SPPh 3 ) 3 ][BPh 4 ] by iodide exchange with Na[BPh 4 ]. The reaction of [MI 2 (CO) 3 L 2 ] with two equivalents of L (LOPPh 3 (for MW only) or SPPh 3 ) give the dicationic compounds [M(CO) 3 L 4 ]2I. The bis- tetraphenylborate complex [Mo(CO) 3 (SPPh 3 ) 4 ]- [BPh 4 ] 2 was also prepared in the normal manner. Three equivalents of OPPh 3 react with [MI 2 (CO) 3 - (OPPh 3 ) 2 ] to give the dicarbonyl compounds [M(CO) 2 (OPPh 3 ) 5 ]2I in high yield. The mixed ligand complexes [MI 2 (CO) 3 L′L] (MMo or W; LOPPh 3 or SPPh 3 ; L′PPh 3 , AsPh 3 or SbPh 3 ) were synthesized by reaction of [MI 2 (CO) 3 (NCMe) 2 ] with an equimolar quantity of L′ in CH 2 Cl 2 , followed by an in situ reaction with one equivalent of L. The triphenylphosphine complex [MoI 2 (CO) 3 (PPh 3 )- (OPPh 3 )] on stirring in CH 2 Cl 2 for 18 h gave the anionic complex [PPh 3 H][MoI 3 (CO) 3 (OPPh 3 )]. Low temperature 13 C NMR spectra (carbonyl region) for several seven-coordinate complexes are interpreted to suggest structures for these compounds.

Tricyclohexylphosphinecarbondisulphide seven-coordinate complexes of molybdenum(II) and tungsten(II)

The complexes [MI2(CO)3(NCMe)2] (M = Mo or W) react with one equivalent of S2CPCy3 in CH2Cl2 to afford the new seven-coordinate complexes [MI2(CO)3(S2CPCy3)]. Reaction of [MI2(CO)3(NCMe)2] (M = Mo or W), with two equivalents of S2CPCy3 afford the new dicationic complexes [M(CO)2(S2CPCy3)2]2I in good yield. The dicationic nature [W(CO)3(S2CPCy3)2]2I was confirmed by the formation of the complex [W(CO)3(S2CPCy3)2][BPh4]2 by iodide exchange with Na[BPh4]. Further reaction in situ of [M(CO)3(S2CPCy3)2]2I with one equivalent of S2CPCy3 afforded the tris ligand complex [W(CO)3(S2CPCy3)3]2I. The reaction of [W(CO)3(S2CPCy3)3]2I with Na[BPh4] in acetonitrile gave [W(CO)3(S2CPCy3)3][BPh4]2, which confirmed the dicationic nature of [W(CO)3(S2CPCy3)3]2I. The mixed ligand complexes [MI(CO)3(PPh3)(S2CPCy3)]I (M = Mo or W) and [WI(CO)3L(S2CPCy3)]I (L = P(OPh)3, AsPh3 or SbPh3) were synthesised by reaction of [MI2(CO)3-(NCMe)2] with an equimolar quantity of L in CH2Cl2 followed by an in situ reaction with one equivalent of S2CPCy3. The cationic nature of [MI(CO)3(PPh3)(S2CPCy3)]I was confirmed by iodide exchange with Na[BF4] to afford the complexes [MI(CO)3(PPh3)(S2CPCy3)][BF4]. The reaction of two equivalents of [WI2(CO)3(NCMe)(PPh3)] with S2CPCy3 afforded the ligand-bridged complex [W2I4(CO)6(PPh3)2(μ-S2CPCy3)]. Treatment of [WI2(CO)3(NCMe)2] with two equivalents of PPh3 followed by an in situ reaction with one equivalent of S2CPCy3 afforded the dicationic complex [W(CO)3(PPh3)2(S2CPCy3)]2I. The ionic nature of the complex was confirmed by iodide exchange with Na[BPh4] to give [W(CO)3(PPh3)2(S2CPCy3)][BPh4]2. Treatment of [W(CO)3(PPh3)2(S2CPCy3)]2I with one further equivalent of S2CPCy3 afforded the complex [W(CO)3(PPh3)2(S2CPCy3)]2I. The low temperature 13C NMR spectra (carbonyl region) of several-coordinate complexes are interpreted to suggest likely structures for these compounds.

SEVEN-COORDINATE ACETYLACETONATO, HEXAFLUOROACETYLACETONATO AND BENZOYLACETYLACETONATO COMPLEXES OF MOLYBDENUM(II) AND TUNGSTEN(II)

Abstract The complexes [MI2(CO)3(NCMe)2] (M = Mo or W) react in CH2Cl2 with one or two equivalents of PPh3 to give [MI2(CO)3(NCMe)(PPh3)] or [MI2(CO)3(PPh3)2], which when reacted, in situ, with one equivalent of Na[ L L ] [ L L = acetylacetonato (acac), hexafluoroacetylacetonato (hfacac) or benzoylacetylacetonato (bzacac)] give the seven-coordinate complexes [MI(CO)3(PPh3)( L L )] and [MI(CO)2(PPh3)2( L L )], respectively. The low temperature 13C NMR spectra of selected complexes are interpreted to suggest the likely structures of these compounds.

The synthesis, spectroscopic properties and reactions with neutral donor ligands of the novel six different ligand molybdenum(II) complex [MocCl(GeCl3)(CO)(NCMe)(PPh3)(η-MeC2Me)]

Abstract The seven-coordinate complex [MoCl(GeCl 3 )(CO) 2 (NCMe) 2 (PPh 3 )] reacts with an excess of but-2-yne in CH 2 Cl 2 at room temperature to give the six different ligand compound [MoCl(GeCl 3 )(CO)(NCMe)(PPh 3 )(η 2 -MeC 2 Me)] ( 1 ) in good yield. Solid-state 13 C NMR spectroscopy suggests that the but-2-yne ligand is donating four electrons to the molybdenum in 1 . Preliminary studies of the reaction chemistry of 1 with neutral donor ligands are also described.

THE FIRST EXAMPLES OF TRIPHENYLPHOSPHINEOXIDE AND TRIPHENYLPHOSPHINESULPHIDE SEVEN-COORDINATE COMPLEXES OF MOLYBDENUM(II) AND TUNGSTEN(II)

Abstract Seven-coordinate complexes of molybdenum(II) and tungsten(II) have become increasingly important in recent years; in particular the compounds [MX2(CO)3L2] (M = Mo or W; X = Cl or Br; L = PPh3 or AsPh3) have been shown to be catalysts for the ring-opening polymerisation of norbornene and norbornadiene.1,2 It is believed that it is the ease of phosphine or arsine dissociation in these compounds which is the rate determining step in the mechanism. Although many examples of bisphosphine seven-coordinate compounds of the type [MX2(CO)3L2] (M = Mo or W; X = Cl, Br or I; L = PR3) have been reported,3–6 hitherto no examples of seven-coordinate complexes containing the phosphorus(v) ligands triphenylphosphineoxide or triphenylphosphinesulphide have been described. We wish to report in this communication the preparation of some new seven-coordinate complexes of molybdenum(II) and tungsten(II) containing triphenylphosphineoxide and triphenylphosphinesulphide as attached ligands.

Synthesis and reactions of alkyne complexes [MoCl(GeCl3)-(CO)(NCMe)(PPh3)(η2-RC2R)](R = Me or Ph) containing six different monodentate ligands

The complex [MoCl(GeCl3)(CO)2(NCMe)2(PPh3)] reacts with RC2R (R = Me or Ph) in CH2Cl2 to give alkyne complexes [MoCl(GeCl3)(CO)(NCMe)(PPh3)(η2-RC2R)](R = Me 1 or Ph 2) containing six different monodentate ligands. Reaction of 1 with an equimolar quantity of L [L = PPh3, PPh2(C6H11), PMe2Ph, imidazole or 2-methylimidazole] afforded complexes [MoCl(GeCl3)(CO)L(PPh3)(η2-MeC2Me)] in high yield. Equimolar quantities of 1 and L–L {L–L = Ph2P(CH2)nPPh2(n= 1–6), [Fe(η5-C5H4PPh2)2], (C6H11)NCHCHN(C6H11), 2,2′-bipyridine, 1,10-phenanthroline, 4,7-dimethyl-1,10-phenanthroline, 5,6-dimethyl-1,10-phenanthroline, S2CP(C6H11)3 or Ph2P(CH2)2PPh(CH2)2PPh2} gave [MoCl(GeCl3)(CO)(PPh3){σ-Ph2P(CH2)PPh2}(η2-MeC2Me)] and the cationic complexes [Mo(GeCl3)(CO)(PPh3)(L–L)(η2-MeC2Me)]Cl in good yield. The cationic nature of several of these complexes was confirmed by exchange with Na[BPh4] to afford complexes with tetraphenylborate as the counter anion. The fluxionality of some of the complexes was detertmined by variable-temperature 1H NMR spectroscopy. Solution and solid-state 13C NMR spectroscopy was used to confirm that the alkyne ligand in several of these complexes is donating four electrons to the molybdenum.

THE REACTIONS OF [MoCl(GeCl3)(CO)3(NCMe)2] WITH NEUTRAL BI- AND TERDENTATE DONOR LIGANDS

Abstract The reaction of [MoCl(GeCl3)(CO)3(NCMe)2] with an equimolar quantity of L∘L {L∘L = 2,2′-bipy, 1,10-phen, Ph2P(CH2)nPPh2 (n = 1 or 2)} in CH2Cl2 at room temperature gave either [MoCl(GeCl3)(CO)3(L∘L)] (L∘L = 2,2′-bipy or 1,10-phen) (1 and 2) or [MoCl(GeCl3)(CO)2 (NCMe)(L∘L)]{L∘L = Ph2P(CH2)nPPh2 (n = 1 or 2) (3 or 4), respectively. Equimolar quantities of [MoCl(GeCl3)(CO)2(NCMe){Ph2P(CH2)PPh2}] (3) and L∘L {L∘L = 2,2′-bipy or Ph2P(CH)2PPh2} react in CH2Cl2 at room temperature to afford the cationic complexes [Mo(GeCl3)(CO)2{Ph2P(CH2) PPh2}(L∘L)]Cl (5 and 6) in good yield. The cationic nature of 6 was established by chloride exchange by reacting Na[BPh4] with 6 in acetonitrile to give the tetraphenylborate complex [Mo(GeCl3)(CO)2{Ph2P(CH2)PPh2}2][BPh4] (7). Reaction of equimolar quantities of [MoCl(GeCl3) (CO)3(NCMe)2] and PhP(CH2CH2PPh2)2 in CH2Cl2 at room temperature afforded the dicarbonyl complex [MoCl(GeCl3)(CO)2{PhP(CH2CH2PPh2)2}] (8) in good yield.