Cluster Expansion Reactions of Group 6 and 8 Metallaboranes Using Transition Metal Carbonyl Compounds of Groups 7–9

Abstract

The reinvestigation of an early synthesis of heterometallic cubane-type clusters has led to the isolation of a number of new clusters which have been characterized by spectroscopic and crystallographic techniques. The thermolysis of [(Cp*Mo)(2)B(4)H(4)E(2)] (1: E = S; 2: E = Se; Cp* = η(5)-C(5)Me(5)) in presence of [Fe(2)(CO)(9)] yielded cubane-type clusters [(Cp*Mo)(2)(μ(3)-E)(2)B(2)H(μ-H){Fe(CO)(2)}(2)Fe(CO)(3)], 4 and 5 (4: E = S; 5: E = Se) together with fused clusters [(Cp*Mo)(2)B(4)H(4)E(2)Fe(CO)(2)Fe(CO)(3)] (8: E = S; 9: E = Se). In a similar fashion, reaction of [(Cp*RuCO)(2)B(2)H(6)], 3, with [Fe(2)(CO)(9)] yielded [(Cp*Ru)(2)(μ(3)-CO)(2)B(2)H(μ-H){Fe(CO)(2)}(2)Fe(CO)(3)], 6, and an incomplete cubane cluster [(μ(3)-BH)(3)(Cp*Ru)(2){Fe(CO)(3)}(2)], 7. Clusters 4-6 can be described as heterometallic cubane clusters containing a Fe(CO)(3) moiety exo-bonded to the cubane, while 7 has an incomplete cubane [Ru(2)Fe(2)B(3)] core. The geometry of both compounds 8 and 9 consist of a bicapped octahedron [Mo(2)Fe(2)B(3)E] and a trigonal bipyramidal [Mo(2)B(2)E] core, fused through a common three vertex [Mo(2)B] triangular face. In addition, thermolysis of 3 with [Mn(2)(CO)(10)] permits the isolation of arachno-[(Cp*RuCO)(2)B(3)H(7)], 10. Cluster 10 constitutes a diruthenaborane analogue of 8-sep pentaborane(11) and has a structural isomeric relationship to 1,2-[{Cp*Ru}(2)(CO)(2)B(3)H(7)].

Synthesis and characterization of novel eleven-vertex dimetallaheteroborane clusters containing Heavier group 16 elements

“…As previously reported, the reaction of 1 with [Fe 2 (CO) 9 ] under mild conditions yielded capped cubane cluster 3 [20] and a fused cluster 4 [21]. An unidentified compound, heterometallic cluster [(Cp*Mo) 2 B 4 H 2 S 2 Fe 4 (CO) 9 (m-CO)], 2 has been isolated and characterized in the present study.…”

“…Shorter FeeFe distance is observed between the Fe1eFe2 atoms (2.5074(7) Å), comparable to the sum of the van der Waals radii for metallic iron (2.52 Å), while the lengths (Fe1eFe3, Fe2eFe3, Fe3eFe4) are on average 2.7578 Å. The FeeB and MoeB distances are within the normal range expected [21,27,28].…”

“…The apical Fe1$$$Fe4 separation in 6 (3.386 Å) is significantly longer than that found in other metallaborane clusters [20,21]. The Mo1eMo2 distance in the pentagon is 2.7603(4) Å, while the internal angles within this pentagon are in the range of 88.70(11) to 129.4(2) (107.94 average), slightly less than the expected value (108 ) for a pentagonal planar geometry [31].…”

“…Therefore, it is hypoelectronic [48]: i.e., fewer valence electrons than apparently are required by its geometric structure. The two most commonly observed 11-vertex deltahedra are the octadecahedron [49], identified in [B 11 H 11 ] 2À and the pentacapped trigonal prism in E 11 7À (E ¼ Ga, In, Tl) and [Rh 5 Ni 6 (CO) 21 …”

New Trinuclear Complexes of Group 6, 8, and 9 Metals with a Triply Bridging Borylene Ligand

“…Unlike metallaboranes, which possess direct M−B bonding composed of nonclassical, electron‐deficient, multicenter two‐electron bonds, borylenes are related to classical, electron‐precise, 2c–2e − bonds. Although trimetallic triply bridging borylene complexes of various transitional metals are known, only a few reports are available that show triply bridging bis‐ and tris‐ borylene complexes ( IV – VI ). Remarkably, rhodium‐bridging borylenes are very rare and this category of compounds has drawn significant attention due to their extensive applications in catalysis…”