Mixed-metal cluster chemistry: 32. Synthesis, structure, and reactivity of a trimetallic molybdenum-iridium carbonyl cluster possessing a μ3-η2-benzyne ligand

Michael D. Randles; Vivek Gupta; Peter V. Simpson; Graeme J. Moxey; Alan L. Criddle; Robert Stranger; Marie P. Cifuentes; Mark G. Humphrey

doi:10.1016/j.poly.2012.07.018

Mixed-metal cluster chemistry: 32. Synthesis, structure, and reactivity of a trimetallic molybdenum-iridium carbonyl cluster possessing a μ₃-η²-benzyne ligand

Michael D. Randles, Vivek Gupta, Peter V. Simpson, Graeme J. Moxey, Alan L. Criddle, Robert Stranger, Marie P. Cifuentes, Mark G. Humphrey^*

^*Corresponding author for this work

Research output: Contribution to journal › Article › peer-review

4 Citations (Scopus)

Abstract

The reaction of Mo₂Ir₂(μ-CO)₃(CO) ₇(η⁵-C₅H₅)₂ and Ir(CCCH₂OH)(CO)(PPh₃)₃ in refluxing toluene gives the molybdenum-iridium cluster MoIr₂(μ₃- η²-C₆H₄)(μ-PPh₂)(μ-CO) ₂(CO)₄(η⁵-C₅H₅) (1) in low yield. Mo₂Ir₂(μ-CO)₃(CO) ₆(PPh₃)(η⁵-C₅H₅) ₂ (2) is a possible intermediate en route to 1; reaction of Mo ₂Ir₂(μ-CO)₃(CO)₇(η ⁵-C₅H₅)₂ and Ir(CCCH ₂OH)(CO)(PPh₃)₃ in refluxing dichloromethane affords low yields of 2, and thermolysis of the latter in refluxing toluene gives modest yields of 1. A structural study reveals that 1 consists of a triangular MoIr₂ core with a molybdenum-bound cyclopentadienyl group, two terminal carbonyls at each of the iridium atoms, one carbonyl bridging each of the Mo-Ir bonds, and a PPh₂ moiety spanning the Ir-Ir linkage. The cluster coordination sphere is completed by a face-capping benzyne ligand that ligates η¹- to each iridium atom and η²- to the group 6 metal. A structural study of 2 confirms the tetranuclear Mo ₂Ir₂ core with molybdenum-bound cyclopentadienyl groups, six terminal and three-edge-bridging carbonyls, the latter deployed about an MoIr₂ face, and a triphenylphosphine ligand ligated axially with respect to the carbonyl-bridged plane. Reaction of 1 with PPh₃ in refluxing toluene gives MoIr₂(μ₃-η²- C₆H₄)(μ-PPh₂)(μ-CO)₂(CO) ₃(PPh₃)(η⁵-C₅H₅) (3) in low yield. While X-ray structural authentication of 3 has thus far proven elusive, theoretical studies indicate that an equatorially substituted structure is favored energetically over the axially-substituted isomer by around 20 kJ mol^-1, but this energy difference is not sufficiently large so as to exclude formation of the axial isomer experimentally.

Original language	English
Pages (from-to)	957-962
Number of pages	6
Journal	Polyhedron
Volume	52
DOIs	https://doi.org/10.1016/j.poly.2012.07.018
Publication status	Published - 22 Mar 2013

Access to Document

10.1016/j.poly.2012.07.018

Cite this

@article{19e3b5b916454216b2fef3351e623af7,

title = "Mixed-metal cluster chemistry: 32. Synthesis, structure, and reactivity of a trimetallic molybdenum-iridium carbonyl cluster possessing a μ3-η2-benzyne ligand",

abstract = "The reaction of Mo2Ir2(μ-CO)3(CO) 7(η5-C5H5)2 and Ir(CCCH2OH)(CO)(PPh3)3 in refluxing toluene gives the molybdenum-iridium cluster MoIr2(μ3- η2-C6H4)(μ-PPh2)(μ-CO) 2(CO)4(η5-C5H5) (1) in low yield. Mo2Ir2(μ-CO)3(CO) 6(PPh3)(η5-C5H5) 2 (2) is a possible intermediate en route to 1; reaction of Mo 2Ir2(μ-CO)3(CO)7(η 5-C5H5)2 and Ir(CCCH 2OH)(CO)(PPh3)3 in refluxing dichloromethane affords low yields of 2, and thermolysis of the latter in refluxing toluene gives modest yields of 1. A structural study reveals that 1 consists of a triangular MoIr2 core with a molybdenum-bound cyclopentadienyl group, two terminal carbonyls at each of the iridium atoms, one carbonyl bridging each of the Mo-Ir bonds, and a PPh2 moiety spanning the Ir-Ir linkage. The cluster coordination sphere is completed by a face-capping benzyne ligand that ligates η1- to each iridium atom and η2- to the group 6 metal. A structural study of 2 confirms the tetranuclear Mo 2Ir2 core with molybdenum-bound cyclopentadienyl groups, six terminal and three-edge-bridging carbonyls, the latter deployed about an MoIr2 face, and a triphenylphosphine ligand ligated axially with respect to the carbonyl-bridged plane. Reaction of 1 with PPh3 in refluxing toluene gives MoIr2(μ3-η2- C6H4)(μ-PPh2)(μ-CO)2(CO) 3(PPh3)(η5-C5H5) (3) in low yield. While X-ray structural authentication of 3 has thus far proven elusive, theoretical studies indicate that an equatorially substituted structure is favored energetically over the axially-substituted isomer by around 20 kJ mol-1, but this energy difference is not sufficiently large so as to exclude formation of the axial isomer experimentally.",

keywords = "Carbonyl, Cluster, Cyclopentadienyl, Phosphine, X-ray structure",

author = "Randles, {Michael D.} and Vivek Gupta and Simpson, {Peter V.} and Moxey, {Graeme J.} and Criddle, {Alan L.} and Robert Stranger and Cifuentes, {Marie P.} and Humphrey, {Mark G.}",

year = "2013",

month = mar,

day = "22",

doi = "10.1016/j.poly.2012.07.018",

language = "English",

volume = "52",

pages = "957--962",

journal = "Polyhedron",

issn = "0277-5387",

publisher = "Elsevier Ltd.",

}

TY - JOUR

T1 - Mixed-metal cluster chemistry

T2 - 32. Synthesis, structure, and reactivity of a trimetallic molybdenum-iridium carbonyl cluster possessing a μ3-η2-benzyne ligand

AU - Randles, Michael D.

AU - Gupta, Vivek

AU - Simpson, Peter V.

AU - Moxey, Graeme J.

AU - Criddle, Alan L.

AU - Stranger, Robert

AU - Cifuentes, Marie P.

AU - Humphrey, Mark G.

PY - 2013/3/22

Y1 - 2013/3/22

N2 - The reaction of Mo2Ir2(μ-CO)3(CO) 7(η5-C5H5)2 and Ir(CCCH2OH)(CO)(PPh3)3 in refluxing toluene gives the molybdenum-iridium cluster MoIr2(μ3- η2-C6H4)(μ-PPh2)(μ-CO) 2(CO)4(η5-C5H5) (1) in low yield. Mo2Ir2(μ-CO)3(CO) 6(PPh3)(η5-C5H5) 2 (2) is a possible intermediate en route to 1; reaction of Mo 2Ir2(μ-CO)3(CO)7(η 5-C5H5)2 and Ir(CCCH 2OH)(CO)(PPh3)3 in refluxing dichloromethane affords low yields of 2, and thermolysis of the latter in refluxing toluene gives modest yields of 1. A structural study reveals that 1 consists of a triangular MoIr2 core with a molybdenum-bound cyclopentadienyl group, two terminal carbonyls at each of the iridium atoms, one carbonyl bridging each of the Mo-Ir bonds, and a PPh2 moiety spanning the Ir-Ir linkage. The cluster coordination sphere is completed by a face-capping benzyne ligand that ligates η1- to each iridium atom and η2- to the group 6 metal. A structural study of 2 confirms the tetranuclear Mo 2Ir2 core with molybdenum-bound cyclopentadienyl groups, six terminal and three-edge-bridging carbonyls, the latter deployed about an MoIr2 face, and a triphenylphosphine ligand ligated axially with respect to the carbonyl-bridged plane. Reaction of 1 with PPh3 in refluxing toluene gives MoIr2(μ3-η2- C6H4)(μ-PPh2)(μ-CO)2(CO) 3(PPh3)(η5-C5H5) (3) in low yield. While X-ray structural authentication of 3 has thus far proven elusive, theoretical studies indicate that an equatorially substituted structure is favored energetically over the axially-substituted isomer by around 20 kJ mol-1, but this energy difference is not sufficiently large so as to exclude formation of the axial isomer experimentally.

AB - The reaction of Mo2Ir2(μ-CO)3(CO) 7(η5-C5H5)2 and Ir(CCCH2OH)(CO)(PPh3)3 in refluxing toluene gives the molybdenum-iridium cluster MoIr2(μ3- η2-C6H4)(μ-PPh2)(μ-CO) 2(CO)4(η5-C5H5) (1) in low yield. Mo2Ir2(μ-CO)3(CO) 6(PPh3)(η5-C5H5) 2 (2) is a possible intermediate en route to 1; reaction of Mo 2Ir2(μ-CO)3(CO)7(η 5-C5H5)2 and Ir(CCCH 2OH)(CO)(PPh3)3 in refluxing dichloromethane affords low yields of 2, and thermolysis of the latter in refluxing toluene gives modest yields of 1. A structural study reveals that 1 consists of a triangular MoIr2 core with a molybdenum-bound cyclopentadienyl group, two terminal carbonyls at each of the iridium atoms, one carbonyl bridging each of the Mo-Ir bonds, and a PPh2 moiety spanning the Ir-Ir linkage. The cluster coordination sphere is completed by a face-capping benzyne ligand that ligates η1- to each iridium atom and η2- to the group 6 metal. A structural study of 2 confirms the tetranuclear Mo 2Ir2 core with molybdenum-bound cyclopentadienyl groups, six terminal and three-edge-bridging carbonyls, the latter deployed about an MoIr2 face, and a triphenylphosphine ligand ligated axially with respect to the carbonyl-bridged plane. Reaction of 1 with PPh3 in refluxing toluene gives MoIr2(μ3-η2- C6H4)(μ-PPh2)(μ-CO)2(CO) 3(PPh3)(η5-C5H5) (3) in low yield. While X-ray structural authentication of 3 has thus far proven elusive, theoretical studies indicate that an equatorially substituted structure is favored energetically over the axially-substituted isomer by around 20 kJ mol-1, but this energy difference is not sufficiently large so as to exclude formation of the axial isomer experimentally.

KW - Carbonyl

KW - Cluster

KW - Cyclopentadienyl

KW - Phosphine

KW - X-ray structure

UR - http://www.scopus.com/inward/record.url?scp=84875409554&partnerID=8YFLogxK

U2 - 10.1016/j.poly.2012.07.018

DO - 10.1016/j.poly.2012.07.018

M3 - Article

SN - 0277-5387

VL - 52

SP - 957

EP - 962

JO - Polyhedron

JF - Polyhedron

ER -

Mixed-metal cluster chemistry: 32. Synthesis, structure, and reactivity of a trimetallic molybdenum-iridium carbonyl cluster possessing a μ₃-η²-benzyne ligand

Abstract

Access to Document

Other files and links

Fingerprint

Cite this