Synthesis and reactivity of novel molecules and solids derived from heavier group 15 cyanate analogues

金属镍（含氮、磷、砷、锑和/或铋的化合物）是一类具有多种结构和化学计量的固体。[1,2]在它们的许多应用中，它们被用作熏蒸剂、杀虫剂、照明弹，也许最值得注意的是，作为半导体它们的物理和化学性质的多样性使得这些化合物在一系列技术应用中很有趣。然而，虽然许多这样的物种可以很容易地用各种方法合成，但这些方法往往需要很高的能量消耗。此外，我们获得明确的纳米级材料的能力仍然受到现有技术方法的极大限制。这就是我们要解决的挑战。我们的目标是研究在合成新分子、簇、纳米颗粒和结构固体中使用替代的含氧试剂。考虑到这一点，我们将探索氰酸阴离子的含更重的PnCO- (Pn = P-Bi)类似物与过渡和后过渡金属盐的反应性。初步研究表明，这类物质很容易发生脱碳反应，作为E-源。2-磷酸乙酯离子（PCO-）于1992年由Becker及其同事首次报道，直到最近才进行了有限的研究[8,9]。2012年，格鲁茨马赫和康明斯的两份独立报告重新唤起了人们对这种不同寻常的阴离子物种的兴趣。[10,11]最近，我们观察到PCO-也可以通过K3P7溶液的直接羰基化得到，收率中等到较高2014年报道了一种新的最先进的阴离子合成方法，允许从廉价的前体（方案1）开始分离数克（100克）钠盐我们最近扩展了这一研究，以提供更重的含砷类似物（AsCO-），它也可以从元素砷和金属钠中高产地分离出来这些合成上的突破将这些阴离子从单纯的化学好奇心转变为合成新型含磷和含砷分子物种的可行合成原料。话虽如此，由于它们相对新颖，这些化合物在合成固体和分子簇方面的应用在很大程度上仍未被探索。我们的目标是在较重的15族氰酸类似物（PnCO-）与各种金属盐（在存在和不存在强配体和/或表面活性剂分子的情况下）之间进行溶液相复分解反应，目的是开发一种新的自下而上的金属nictides方法。我们的第一个目标是在PnCO- (Pn = P, As)碱金属盐与13族元素（例如GaI）的低卤化物之间进行概念验证反应，目的是确定通向III/V半导体材料（如GaP）的新途径。III-V半导体，如GaAs， Ga1-xInxP和InP，由于其最佳带隙和高吸收系数，被认为是光电器件的有吸引力的候选者。除了光伏应用外，[15]还被广泛应用于固态激光器、led和光波导中。[16-19]目前两种较重的氰酸盐类似物的可用性也为合成诸如GaAs1-xPx之类的混合硝基化合物提供了可能性，GaAs1-xPx是一种具有巨大工业兴趣的用于字母数字和图形显示的化合物。该项目属于EPSRC物理科学研究主题（特别是化学合成方法领域）。

Metal pnictides (compounds containing nitrogen, phosphorus, arsenic, antimony and/or bismuth) are a varied family of solids that adopt a wealth of structures and stoichiometries.[1,2] Amongst their many applications they have been employed as fumigants, pesticides, flares and, perhaps most notably, as semiconductors.[3] The diversity of their physical and chemical properties makes such compounds interesting for a range of technological applications. However, while many such species can be readily synthesised using a variety of methods, these often come at a high energetic cost. Moreover, our ability to access well defined nanoscale materials is still significantly limited by existing technological methods. This is the challenge we propose to address.Our goal is to study the use of alternative pnictogen-containing reagents for the synthesis of novel molecules, clusters, nanoparticles and structured solids. With this in mind, we will explore the reactivity of heavier pnictogen-containing analogues of the cyanate anion, PnCO- (Pn = P-Bi), with transition- and post-transition metal salts. Preliminary studies have shown that such species readily undergo decarbonylation reactions acting as E- sources. The 2-phosphaethynolate ion (PCO-) was first reported by Becker and co-workers in 1992 and was the subject of limited study until very recently.[8,9] In 2012, two separate reports by Grutzmacher and Cummins revived the interest in this remarkable anionic species.[10,11] More recently, we observed that PCO- can also be obtained by direct carbonylation of solutions of K3P7 in moderate to good yields.[12] A novel state-of-the-art synthesis of this anion was reported in 2014 allowing for the isolation of sodium salts in multi-gram quantities (> 100 grs.) starting from inexpensive precursors (Scheme 1).[13] We recently extended this research to afford the heavier arsenic-containing analogue (AsCO-) which can also be isolated in high yields from elemental arsenic and sodium metal.[14] These synthetic breakthroughs have transformed these anions from mere chemical curiosities to viable synthetic feedstocks for the synthesis of novel phosphorus- and arsenic-containing molecular species. That being said, due to their relative novelty, the use of these compounds for the synthesis of solids and molecular clusters remains largely unexplored.Our goal is to carry out solution-phase metathesis reactions between heavier group 15 cyanate analogues (PnCO-) with a variety of metal salts (in the presence and absence of strongly coordinating ligands and/or surfactant molecules), with the aim of developing a novel bottom-up approach to metal pnictides. Our first objective is to carry out proof-of-concept reactions between alkali metal salts of PnCO- (Pn = P, As) with the lower halides of the group 13 elements (e.g. GaI) with the objective of identifying a novel route towards III/V semiconductor materials (such as GaP). III-V semiconductors such as GaAs, Ga1-xInxP, and InP are considered attractive candidates for optoelectronic devices due to their optimal band gaps and high absorption coefficients. In addition to photovoltaic applications,[15] they have been widely utilized in solid state lasers, LEDs, and optical waveguides.[16-19] The current availability of two heavier cyanate analogues also opens up the possibility of synthesising mixed pnictide species such as GaAs1-xPx, which is a compound of enormous industrial interest for alpha-numeric and graphical displays.This project falls within the EPSRC Physical Sciences research theme (specifically the Chemical Synthetic Methodology area).