Synthesis and characterization of platinum(II)-bis(boryl) catalyst precursors for diboration of alkynes and diynes: Molecular structures of cis-[(PPh(3))(2)Pt(B-4-Bu(t)cat)(2)], cis-[(PPh(3))(2)Pt(Bcat)(2)], cis-[(dppe)Pt(Bcat)(2)], cis-[(dppb)Pt(Bcat)(2)], (E)-(4-MeOC(6)H(4))C(Bcat)=CH(Bcat), (Z)-(C6H5)C(Bcat)=C(C6H5)(Bcat), and (Z,Z)-(4-MeOC(6)H(4))C(Bcat)=C(Bcat)C(Bcat)=C(4-MeOC(6)H(4))(Bcat) (cat equals 1,2-O2C6H4; dppe equals Ph(2)PCH(2)CH(2)PPh(2); dppb equals Ph(2)P(CH2)(4)PPh(2))
Synthesis and characterization of platinum(II)-bis(boryl) catalyst precursors for diboration of alkynes and diynes: Molecular structures of cis-[(PPh(3))(2)Pt(B-4-Bu(t)cat)(2)], cis-[(PPh(3))(2)Pt(Bcat)(2)], cis-[(dppe)Pt(Bcat)(2)], cis-[(dppb)Pt(Bcat)(2)], (E)-(4-MeOC(6)H(4))C(Bcat)=CH(Bcat), (Z)-(C6H5)C(Bcat)=C(C6H5)(Bcat), and (Z,Z)-(4-MeOC(6)H(4))C(Bcat)=C(Bcat)C(Bcat)=C(4-MeOC(6)H(4))(Bcat) (cat equals 1,2-O2C6H4; dppe equals Ph(2)PCH(2)CH(2)PPh(2); dppb equals Ph(2)P(CH2)(4)PPh(2))
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DOI：
10.1021/om950918c
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发表时间：
1996-11-26
期刊：
影响因子：
2.8
通讯作者：
Norman, NC
中科院分区：
文献类型：
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作者：
Lesley, G;Nguyen, P;Norman, NC
B-B键化合物B-2(CAT)(2)(CAT=1，2-O2C6H4)(1a)、B-2(4-Bu(T)-CAT)(2)(1b)和B-2(OCME(2)CME(2)O)(2)(1c)与铂(O)-双(膦)配合物[(PPh(3)(2)Pt(ETA-C2H4)](4)通过B-B键的氧化加成生成顺式双(硼基)铂(II)配合物。顺式[(PPh(3))(2)铂(BCAT)(2)]的分子结构。用单晶X射线衍射法测定了C6D6(3a)和顺式[(PPh(3))(2)铂(B-4-Bu(T)CAT)(2)](3b)。3a与1当量的双齿膦dppe(Ph(2)PCH(2)CH(2)PPh(2))或dppb(Ph(2)P(CH2)(4)PPh(2))在甲苯中反应顺利，分别得到顺式[(Dppe)铂(BCAT)(2)](5a)和顺式[(Dppb)铂(BCAT)(2)](5b)。化合物3a、b和4是烯烃和1，3-二炔二硼化合成的高活性催化剂前体。X-射线晶体结构(E)-(4-MEOC(6)H(4))C(BCAT)=CH(BCAT)(10c)，(Z)-(C6H5)C(BCAT)=C(C6H5)(BCAT)(10e)和(Z，Z)-(4-MeOC(6)H(4))C(Bcat)=C(Bcat)C(Bcat)=C(4-MeOC(6)H(4))(Bcat)(14a))证实了三种典型情况下Baron取代基的顺式立体化学，即，端炔4-MEOC(6)H(4)C=CH，内炔PHC=CPH，以及二炔4，4‘-MEOC(6)H(4)C=CC=CC(6)H(4)OMe的催化二硼化产物。在催化反应中，C=CSiMe(3)部分的存在会产生不同于炔基二硼化产物的额外产物。二硼试剂和C-Si键裂解产物的复分解反应产生了新的三(硼酸酯)，这是竞争过程中形成的C=CB(OR(2))部分随后发生二硼反应的结果。化合物5a没有催化活性，5b具有极强的规律性，在添加PPh(3)的情况下，3b的活性急剧下降，这表明膦的解离是催化过程中的关键步骤。
The reactions of the B-B-bonded compounds B-2(cat)(2) (cat = 1,2-O2C6H4) (1a), B-2(4-Bu(t)-cat)(2) (1b), and B-2(OCMe(2)CMe(2)O)(2) (1c) with the Pt(O)-bis(phosphine) complex [(PPh(3))(2)Pt(eta-C2H4)] (4) via oxidative addition of the B-B bond yield cis-bis(boryl) Pt(II) complexes. The molecular structures of cis-[(PPh(3))(2)Pt(Bcat)(2)]. C6D6 (3a) and cis-[(PPh(3))(2)Pt(B-4-Bu(t)cat)(2)] (3b) were determined by single-crystal X-ray diffraction. Reaction of 3a with 1 equiv of the bidentate phosphine dppe (Ph(2)PCH(2)CH(2)PPh(2)) or dppb (Ph(2)P(CH2)(4)PPh(2)) proceeds smoothly in toluene to give cis-[(dppe)Pt(Bcat)(2)] (5a) and cis-[(dppb)Pt(Bcat)(2)] (5b), respectively, which have also been characterized by X-ray diffraction. Compounds 3a,b and 4 are highly active catalyst precursors for the diboration of alkynes and 1,3-diynes. X-ray crystal structures of (E)-(4-MeOC(6)H(4))C(Bcat)=CH(Bcat) (10c), (Z)-(C6H5)C(Bcat)=C(C6H5)(Bcat) (10e), and (Z,Z)-(4-MeOC(6)H(4))C(Bcat)=C(Bcat)C(Bcat)=C(4-MeOC(6)H(4))(Bcat) (14a) confirm the cis stereochemistry of the baron substituents in three representative cases, namely, products of the catalyzed diboration of the terminal alkyne 4-MeOC(6)H(4)C=CH, the internal alkyne PhC=CPh, and the tetraboration of the diyne 4,4'-MeOC(6)H(4)C=CC=CC(6)H(4)OMe. The presence of the C=CSiMe(3) moiety in catalytic reactions gives rise to additional products other than those derived from the diboration of the alkyne group. Metathetical reactions involving the diboron reagent and products derived from C-Si bond cleavage give rise to novel tris(boronate esters) as a result of the subsequent diboration of the C=CB(OR(2)) moieties formed by this competing process. The absence of catalytic activity using compound 5a, the extremely law activity of 5b, and the strong decrease in activity of 3b in the presence of added PPh(3) suggests that phosphine dissociation is a critical step in the catalytic pathway.