Date of Award

2010

Document Type

Campus Access Dissertation

Department

Chemistry and Biochemistry

Sub-Department

Chemistry

First Advisor

Richard D. Adams

Abstract

The complex Re2(CO)8[-2-C(H)=C(H)Bun](-H), 2.1 reacts with SbPh3 at 68 oC to yield the new σ-phenyl dirhenium complex Re2(CO)8(SbPh3)(Ph)(μ-SbPh2), 2.4 in 72% yield. Compound 2.4 contains two rhenium atoms held together by a bridging SbPh2 ligand. One rhenium atom contains a σ-phenyl group. The other rhenium atom contains a SbPh3 ligand. Compound 2.4 was also obtained in 34% yield from the reaction of Re2(CO)10 with SbPh3 in the presence of UV-vis irradiation together with some monorhenium products: HRe(CO)4SbPh3, 2.5, Re(Ph)(CO)4SbPh3, 2.6 and fac-Re(Ph)(CO)3(SbPh3)2, 2.7 in low yields. Complex 2.4 is split by reaction with an additional quantity of SbPh3 to yield the monorhenium SbPh3 complexes 2.6, 2.7 and mer-Re(Ph)(CO)3(SbPh3)2, 2.8 that contain a σ-phenyl ligand. When 2.4 was treated with hydrogen, the phenyl ligand was eliminated as benzene and the dirhenium complexes Re2(CO)8(μ-SbPh2)(μ-H), 2.10, and Re2(CO)7(SbPh3)(μ-SbPh2)(μ-H), 2.11, were formed that contain a bridging hydrido ligand. The doubly SbPh2-bridged dirhenium complex Re2(CO)7(SbPh3)(μ-SbPh2)2, 2.9 that has no metal - metal bond was also formed in these two reactions.

The reaction of 2.1 with BiPh3 in heptane solvent at reflux yielded three new compounds Re2(CO)8(μ-BiPh2)2, 3.1 (14% yield), [Re(CO)4(μ-BiPh2)]3, 3.2 (5% yield) and Re2(η6-C6H5Ph)(CO)7, 3.3, 4.7 mg (7% yield). Compound 3.1 contains two Re(CO)4 groups joined by two bridging BiPh2 ligands in a four-membered ring. There is no Re -Re bond in 3.1, Re...Re = 4.483(1) Å. Compound 3.2 contains a six-membered Re3Bi3 ring in a twist-boat conformation. When heated to 110 oC in toluene, compound 3.1 was transformed into the heterocycle 3.2 (8% yield), the known compound Re(CO)5Ph, 3.4 (25% yield) and the new compound Re2(CO)8(μ-BiPh)2, 3.5 (4% yield). Compound 3.5 contains two Re(CO)4 groups joined by two bridging BiPh ligands and a Re - Re bond, Re - Re = 3.1006(18) Å. When compound 3.2 was heated to reflux in an octane solution, it was converted to two new compounds: cis-Re4(CO)16(μ-BiPh2)2(μ4-BiPhBiPh), cis-3.6 and trans-Re4(CO)16(μ-BiPh2)2(μ4-BiPhBiPh), trans-3.7 and a small amount of 3.1 (3% yield). Cis-3.6 and trans-3.7 are isomers. Both compounds contain two fused Re2Bi3 rings that share a quadruply bridging BiPhBiPh ligand that contains a Bi - Bi bond; Bi - Bi = 3.0237(7) Å in cis-3.6 and Bi - Bi = 2.9765(3) Å in trans-3.7. The phenyl groups on the bridging BiPhBiPh ligand in cis-3.6 have a cis-orientation and in trans-3.7 they have a trans-orientation. In the presence of visible light, cis-3.6 and trans-3.7 are transformed into yet another isomer Re4(CO)16(μ-BiPh2)2(μ-BiBiPh2), 3.8 by a shift of one of the phenyl ligands on the bridging BiPhBiPh ligand to the neighboring bismuth atom. Compound 3.8 contains two fused rings, one five-membered Re2Bi3 ring and one four-membered Re2Bi2 ring.

The heterocyclic rhenium-bismuth complex Re3(CO)12(μ-H)2(μ-BiPh2), 3.9 was obtained in 62 % yield from the reaction of [Bu4N][Re3(CO)12(-H)2] with BiPh2Cl at room temperature. Compound 3.9 was converted to the [Bu4N] salt of the dihydrido monoanion [{HRe(CO)4}2(μ-BiPh2)], 3.10 by reaction with [Bu4N][OH]. The anion of 3.10 contains a BiPh2 ligand bridging two HRe(CO)4 groups. The corresponding [Bu4N] salt of the SbPh2-bridged monoanion [{HRe(CO)4}2(μ-SbPh2)], 3.11was obtained from the reaction of Re2(CO)8(μ-SbPh2)(μ-H), 2.10 with NaBH4 followed by precipitation with [Bu4N]Br. The anion of 3.11 was converted back to 2.10 by treatment with H[BF4], but no characterizable product was obtained from the treatment of 3.10 with H[BF4].

Three products Re2[Pt(PBut3)](-SbPh2)(CO)8(-H), 4.2, Re2[Pt(CO)(PBut3)]Ph(CO)8(3-SbPh)(-H), 4.3 and Re2[Pt(PBut3)]2(CO)8(4-Sb2Ph2)(-H)2, 4.4 were obtained from the reaction of Re2(CO)8(-SbPh2)(-H), 2.10 with Pt(PBut3)2. Compound 4.3 was also obtained from 4.2 by further reaction with Pt(PBut3)2. Compound 4.2 is a Pt(PBut3) adduct of 2.10 formed by the insertion of the platinum atom into one of the Re - Sb bonds of 2.10 with formation of two Pt - Re bonds. Compound 4.3 contains an open Re2Pt cluster and was also obtained in a low yield by the addition of CO to 4.2 The addition of SbPh3 to 4.2 yielded the compound Re2Pt(PBut3)(Ph)(CO)8(SbPh3)(3-SbPh)(-H), 4.5, a SbPh3 derivative of 4.3. Compound 4.4 can be viewed as a dimer of the fragment Re[Pt(PBut3)](CO)4(SbPh)(-H). The two halves of the molecule are held together by Pt - Sb bonds and a significant interaction directly between the Sb atoms, Sb - Sb distance, 2.9834(7) Å. The Sb - Sb bonding in 4.4 was explained by density functional calculations. Compound 4.4 adds two equivalents of CO at 1 atm/25 oC, one to each platinum atom, to yield the compound [Re(CO)4Pt(H)(CO)(PBut3)(3-SbPh)]2 which exists as a mixture of two noninterconverting isomers, cis-4.6 and trans-4.6. Both isomers of 4.6 were isolated and structurally characterized. Each isomer of 4.6 consists of a central planar Re2Sb2 core composed of two Re(CO)4 groups with two bridging SbPh ligands. There is a Pt(H)(CO)(PBut3) group coordinated to each antimony atom of 4.6. In the cis-isomer both Pt(H)(CO)(PBut3) groups lie on the same side of the Re2Sb2 plane. In the trans-isomer the Pt(H)(CO)(PBut3) groups lie on opposite sides of the Re2Sb2 plane.

The reaction of [Re(CO)4(-SbPh2)]2, 2.16 with Pt(PBut3)2 in octane solvent at reflux (125 oC) has yielded two platinum-rhenium-antimony compounds: Re2(CO)8[(μ-SbCH2CMe2)Pt(H)PBut2]PBut3(μ-SbPh2), 5.1 and Re2(CO)8[Pt(CO)(CH2CMe2)PBut2](μ3-SbPh)(μ-SbPh2), 5.2 in low yields. Both products were formed by cleavage of phenyl group(s) from one of the bridging SbPh2 ligands in 2.16 and addition of a PtPBut3 or Pt[PBut3]2 group to the antimony atom. In both products one of the t-butyl groups was metalated on one of its methyl groups. In 5.1 the metalation occurred on the antimony atom while in 5.2 it occurred on the platinum atom. When the same reaction was performed under an atmosphere of hydrogen (1 atm), two additional new platinum-rhenium-antimony compounds PtRe2(CO)8PBut3(μ3-SbPh)(μ-SbPh2)(μ-H), 5.3 and Re2(CO)8[PtH(CO)PBut3](μ3-SbPh)(μ-SbPh2), 5.4 were formed. In both products, a phenyl group was cleaved from one of the bridging SbPh2 ligands in 2.16 and addition of a PtPBut3 group to the antimony atom, but there was no metalation of the t-butyl groups in these products. Instead, a hydride ligand was added to the complex. Compound 5.4 was also obtained from 5.3 by the addition of CO. Compound 5.3 also reacts with SbPh3 to form the new compound PtRe2(CO)7PBut3(μ3-SbPh)(μ-SbPh2)2, 5.5 (42% yield) which contains an addition bridging SbPh2 ligand across the Pt - Re bond. The reaction of 5.5 with Pt[PBut3]2 yielded the new compound Pt2Re2(CO)7[PBut3]2(μ3-SbPh)3, 5.6 by cleavage of one phenyl ring from each of the two SbPh2 ligands in 5.5 and the addition of a PtPBut3 group to the resultant SbPh ligands. Compound 5.6 contains three triply-bridging SbPh ligands. Pt(PBut3)2 reacts with the rhenium-hydride complex HRe(CO)4(SbPh3), 2.5 at 25 oC to give the complex PtRe(CO)4(Ph)(PBut3)(μ-SbPh2)(μ-H), 6.1 in 75% yield by the oxidative-addition of a PtPBut3 group into an Sb - C bond on the SbPh3 ligand of 2.5. Compound 6.1 contains a Pt - Re bond, Pt(1) - Re(1) = 3.0971(7) Å, with a bridging SbPh2 ligand and a bridging hydrido ligand. At 98 oC, Pt(PBut3)2 reacts with two equivalents of 2.5 to yield the compounds PtRe2(CO)8[PH(But2)](Ph)(μ-SbPh2)2(μ-H), 6.2, PtRe2(CO)8(SbPh3)(Ph)(μ-SbPh2)2(μ-H), 6.3 and PtRe2(P-t-Bu3)(μ-SbPh2)2(μ-SbPh), 6.4. Compounds 6.2 and 6.3 both contain five-membered Re2Sb2Pt rings formed from two mutually-bonded Re(CO)4 groups and two bridging SbPh2 ligands that are both bonded to the Pt atom. Compound 6.3 was obtained from 6.1 independently by reaction with 2.5. Pt(PBut3)2 reacts with 2.5 at 68 oC under a hydrogen atmosphere to yield 6.1, 6.3 and the new compound HPtRe2(CO)8(PBut3)(μ-SbPh2)2(μ-H), 6.5 which also contains five-membered Re2Sb2Pt ring similar to those found in 6.2 and 6.3. Five compounds were obtained in low yields when 6.1 was thermally decomposed under nitrogen at 100 oC: a colorless band of 2.16, 0.5 mg (6%), a colorless band of 2.6, 0.5 mg (4%), a colorless band of Re2(CO)8[PtH(CO)(PBut3)](μ3-SbPh)(μ-SbPh2), 5.4, 0.5 mg (4%), an orange band of PtRe2(PBut3)(μ-SbPh2)2(μ-SbPh), 5.5, 0.5 mg (4%), and a brown band of RePh(CO)4[PtH(CO)PBut3](μ-SbPh2), 6.6, 1.2 mg (7%).Of these only 6.6 is new. Compound 6.6 is a CO adduct of 6.1, and was obtained independently by the addition of CO to 6.1. The CO ligand was added to the platinum atom and the Pt - Re bond of 6.1 was cleaved and the phenyl group was shifted to the rhenium atom. The two metal atoms are linked solely by the bridging SbPh2 ligand. Seven compounds: 6.3 (9% yield), 2.16 (26%), Pt3(CO)3(PBut3)3, 6.5 (71%), 5.4 (7%), 6.6 (8%), PtRe2(CO)9PBut3(μ-H)2, 4.7(13%) and Re3(CO)13(μ3-SbPh)(μ-SbPh2), 2.19 (18%) were obtained when 6.1 was allowed to react with CO at room temperature.

Pt(PBut3)2 reacts with the bismuthtrirhenium complex Re3(CO)12(-BiPh2)(μ-H)2, 3.9 at 68 oC to give seven complexes PtRe2(CO)9P(But3)(μ-H)2, 4.7, PtRe3(CO)12PBut3(μ-Ph)(μ-H)(μ4-Bi), 7.1, PtRe3(CO)13PBut3(μ4-Bi)(μ-H)2, 7.1, PtRe4(CO)16P(But3)(μ-H)2(μ4-Bi)(μ3-Bi), 7.3, Pt2Re5(CO)21[PBut3]2(μ-H)3(μ4-Bi)2, 7.4, trans-Pt2Re5(CO)22[PBut3]2(μ-H)3(μ4-Bi)2, trans-7.5, cis-Pt2Re5(CO)22[PBut3]2(μ-H)3(μ4-Bi)2, cis-7.5, and Re3(CO)13[PtPBut3]2(μ-H)2(μ4-Bi), 7.6, all in low yields. When 7.2 was treated with Pt(P-But3)2 at 68 oC, compounds 4.7, trans-7, cis-Pt2Re5(CO)22[PBut3]2(μ-H)3(μ4-Bi)2, cis-7 and Pt2Re4(CO)18[PBut3]2(μ-H)2(μ4-Bi)2, 7.7 were formed. When 7.6 was treated with CO at 25 oC, compounds 4.7, trans-7.5, 7.7, and PtRe3(CO)9PBut3(μ3-Bi)(μ4-Bi2), 7.8 were formed. In all of the products both of the phenyl rings from the bridging BiPh2 ligand of 3.9 were cleaved from the bismuth atom. Only one compound 7.1 contained a phenyl ligand and the ligand was a bridging ligand across the Pt - Re bond. All of the products, except the known compound 4.7, contained bridging, 4-Bi ligands. The higher nuclearity complexes 7.3, 7.4, trans-7.5, cis-7.5, and 7.7 contained two bismuth ligand. Compound 7.8 contained three bismuth atoms. Two of the bismuth atoms in 7.8 were part or an octahedrally-shaped Re3PtBi2 cluster. The third bismuth atom was a triply-bridging ligand on the Re3 face of the cluster. The molecular structures of all of the new complexes were characterized by single-crystal x-ray diffraction analyses.

Five new compounds were obtained from the reaction of Os3(CO)11(NCMe), 8.1 with BiPh3 in hexane solution at reflux. These have been identified as Os2(CO)8(μ-BiPh), 8.2, Os(CO)4Ph2, 8.3, Os4(CO)14(μ-3-O=CC6H5)(μ4-Bi), 8.4, Os4(CO)15Ph(μ4-Bi), 8.5, and Os5(CO)19Ph(μ4-Bi), 8.6. Cleavage of the phenyl groups from the BiPh3 was the dominant reaction pathway. Fragmentation of the original triosmium cluster was accompanied by reaggregation processes that were facilitated by the naked bismuth to yield the higher nuclearity osmium cluster complexes containing spiro-bridging bismuth ligands. Compound 8.6 was photo-decarbonylated to yield the compound HOs5(CO)18(μ-2-C6H4)(μ4-Bi), 8.7 formed by ortho-CH activation of the -bonded phenyl ring in 8.6 to form a bridging 2-benzyne ligand. Compounds 8.2 - 8.7 were each characterized structurally by a single-crystal x-ray diffraction analysis.

Rights

© 2010, William Cecil Pearl Jr.

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