Premium
Reactivity of Silyl‐Substituted Heterobimetallic Iron–Platinum Hydride Complexes towards Unsaturated Molecules, I Alkyne Insertions into the Platinum‐Hydride Bond, Phosphane‐Induced σ‐Alkenyl–μ‐Vinylidene Rearrangements and Formation of μ‐Isonitrile Complexes
Author(s) -
Knorr Michael,
Strohmann Carsten
Publication year - 2000
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/(sici)1099-0682(200002)2000:2<241::aid-ejic241>3.0.co;2-y
Subject(s) - chemistry , hydride , phenylacetylene , platinum , alkyne , medicinal chemistry , oxidative addition , stereochemistry , cyclopentadienyl complex , ligand (biochemistry) , crystallography , metal , catalysis , organic chemistry , biochemistry , receptor
The heterobimetallic hydride complexes [(OC) 3 Fe{Si(OMe) 3 }(μ‐Ph 2 PXPPh 2 )Pt(H)(PR 3 )] ( 1a : X = CH 2 , PR 3 = PPh 3 ; 1b : X = NH, PR 3 = PPh 3 ; 1c : X = CH 2 , PR 3 = PMePh 2 ) have been prepared by the oxidative addition of [(OC) 3 Fe(H){Si(OMe) 3 }(η 1 ‐Ph 2 PXPPh 2 )] to [Pt(H 2 CCH 2 )(PPh 3 ) 2 ] or by reaction of K[(OC) 3 Fe{Si(OMe) 3 }(η 1 ‐dppm)] with trans ‐[Pt(Cl)(H)(PPh 3 ) 2 ]. The solid‐state structure of compound 1b has been determined by single‐crystal X‐ray diffraction. 1‐Alkynes such as methylpropiolate or phenylacetylene insert in a regiospecific manner into the Pt–H bond of 1 to yield the σ‐alkenyl complexes [(OC) 3 Fe{μ‐Si(OMe) 2 (OMe)}(μ‐Ph 2 PXPPh 2 )Pt{C(R)=CH 2 }] ( 2a : X = CH 2 , R = CO 2 Me; 2b : X = NH, R = CO 2 Me; 3a : X = CH 2 , R = Ph). Addition of the Pt–H bond of 3a across the triple bond of [D 1 ]phenylacetylene affords [(OC) 3 Fe{μ‐Si(OMe) 2 (OMe)}(μ‐dppm)Pt{C(Ph)=C(D)H}] ( 3a* ) having the deuteron trans to platinum ( cis addition). This insertion reaction is accompanied by dissociation of the platinum‐bonded PR 3 ligand and saturation of the vacant coordination site by a dative μ‐η 2 ‐Si–O→Pt interaction. When 3 is treated with PR 3 again, a subsequent phosphane‐induced rearrangement leading to vinylidene‐bridged complexes [(OC) 3 Fe{μ‐CC(H)R′}(μ‐Ph 2 PXPPh 2 )Pt(PR 3 )] ( 4a : X = CH 2 , R′ = Ph, PR 3 = PPh 3 ; 4b : X = NH, R′ = Ph, PR 3 = PPh 3 ; 4c : X = CH 2 , R′ = Ph, PR 3 = PMePh 2 ; 4d : X = CH 2 , R′ = p ‐tolyl, PR 3 = PPh 3 ) occurs. Upon purging a solution of 3a with carbon monoxide, the labile CO adduct [(OC) 3 Fe{Si(OMe) 3 }(μ‐dppm)‐Pt(CO){C(Ph)=CH 2 }] 5a is formed, addition of 2,6‐xylyl isocyanide to 2a and 3a affords the isonitrile adducts [(OC) 3 Fe{Si(OMe) 3 }(μ‐dppm)Pt(CNxylyl){C(R)=CH 2 }] ( 5b : R = CO 2 Me; 5c : R = Ph), respectively. When hydride complex 1a is allowed to react with stoichiometric amounts of aromatic isonitriles, formal elimination of HSi(OMe) 3 occurs, yielding the heterodinuclear isonitrile‐bridged complexes [(OC) 3 Fe(μ‐C=N‐R)(μ‐dppm)Pt(PPh 3 )] ( 6a : R = 2,6‐xylyl; 6b : R = o ‐anisyl; 6c : R = p ‐anisyl; 6d : R = p ‐C 6 H 4 NH 2 ) and the bis(isonitrile) complexes [(OC) 2 (RN≡C)Fe(μ‐C=N–R)(μ‐dppm)Pt(PPh 3 )] ( 7a : R = 2,6‐xylyl; 7b : R = p ‐anisyl). Single‐crystal X‐ray diffraction studies perfomed on 6a and 6b reveal that the molecular structures of these μ‐isonitrile complexes closely resemble the μ‐vinylidene complexes 4 . The two metal centers are bridged in a symmetric manner by strongly bent CNR ligands, the aromatic groups R being oriented towards the Fe(CO) 3 moiety. Electrophilic addition of HBF 4 to the basic nitrogen atom of the μ‐CNR ligand transforms 6 to the cationic μ‐aminocarbyne complexes [(OC) 3 Fe{μ‐CN(H)R}(μ‐dppm)Pt(PPh 3 )][BF 4 ] ( 8a : R = 2,6‐xylyl; 8b : R = p ‐anisyl; 8c : R = p ‐C 6 H 4 NH 2 ).